Biomedical subjects

A Hessel

Publications and source records attributed to A Hessel.

29 records · Page 2Linked to original sources

PubMed1994

The XbaI-BlnI-CeuI genomic cleavage map of Salmonella paratyphi B.

The genomic cleavage map of Salmonella paratyphi B was determined through digestion with endonucleases and separation of the fragments by pulsed-field gel electrophoresis. The chromosome has 19 XbaI sites, 10 BlnI sites, and 7 CeuI sites. The fragments were arranged in order through excision of fragments from the gel, redigestion with a second enzyme, end labelling with 32P, and reelectrophoresis. Tn10 transposons inserted in 61 different genes of S. typhimurium LT2 were transduced by use of bacteriophage P22 into S. paratyphi B. The locations of Tn10 insertions on the chromosome of S. paratyphi B were determined by use of XbaI and BlnI sites in Tn10, revealing the positions of genes with Tn10 insertions in S. paratyphi B. All seven CeuI sites (in rrl genes for 23S rRNA) and most of the XbaI and BlnI sites in rrn genes for Glt-tRNA are conserved, but only about half of the XbaI and BlnI sites outside rrn genes are conserved. Gene order is identical in the 68 genes that we could compare between S. paratyphi B and S. typhimurium LT2, and the lengths of intervals between the genes are often the same, but there are several instances of differences in interval lengths, indicating that insertions or deletions of DNA have occurred during the evolutionary divergence of these bacteria.

Bacteriophage P22↗

PubMed1994

Molecular analysis of the rfaD gene, for heptose synthesis, and the rfaF gene, for heptose transfer, in lipopolysaccharide synthesis in Salmonella typhimurium.

We report the analysis of three open reading frames of Salmonella typhimurium LT2 which we identified as rfaF, the structural gene for ADP-heptose:LPS heptosyltransferase II; rfaD, the structural gene for ADP-L-glycero-D-manno-heptose-6-epimerase; and part of kbl, the structural gene for 2-amino-3-ketobutyrate CoA ligase. A plasmid carrying rfaF complements an rfaF mutant of S. typhimurium; rfaD and kbl are homologous to and in the same location as the equivalent genes in Escherichia coli K-12. The RfaF (heptosyl transferase II) protein shares regions of amino acid homology with RfaC (heptosyltransferase I), RfaQ (postulated to be heptosyltransferase III), and KdtA (ketodeoxyoctonate transferase), suggesting that these regions function in heptose binding. E. coli contains a block of DNA of about 1,200 bp between kbl and rfaD which is missing from S. typhimurium. This DNA includes yibB, which is an open reading frame of unknown function, and two promoters upstream of rfaD (P3, a heat-shock promoter, and P2). Both S. typhimurium and E. coli rfaD genes share a normal consensus promoter (P1). We postulate that the yibB segment is an insertion into the line leading to E. coli from the common ancestor of the two genera, though it could be a deletion from the line leading to S. typhimurium. The G+C content of the rfaLKZYJI genes of both S. typhimurium LT2 and E. coli K-12 is about 35%, much lower than the average of enteric bacteria; if this low G+C content is due to lateral transfer from a source of low G+C content, it must have occurred prior to evolutionary divergence of the two genera.

Amino Acid Sequence↗

PubMed1993

Genomic mapping with I-Ceu I, an intron-encoded endonuclease specific for genes for ribosomal RNA, in Salmonella spp., Escherichia coli, and other bacteria.

Construction of physical maps of genomes by pulsed-field gel electrophoresis requires enzymes which cut the genome into an analyzable number of fragments; most produce too many fragments. The enzyme I-Ceu I, encoded by a mobile intron in the chloroplast 23S ribosomal RNA (rrl) gene of Chlamydomonas eugametos, cuts a 26-bp site in the rrl gene. This enzyme digests DNA of Salmonella typhimurium at seven sites, each corresponding to one of the rrl genes of the rrn operons, but at no other site. These seven fragments were located on the previously determined Xba I physical map, and the I-Ceu I sites, and thus the rrn genes of S. typhimurium, were mapped on the 4800-kb chromosome. Escherichia coli K-12 also yields seven fragments of sizes similar to those of S. typhimurium, indicating conservation of rrn genes and their location, and a chromosome size of 4600 kb. The sizes of the E. coli fragments are close to the size predicted from restriction maps and nucleotide sequence. The I-Ceu I maps of Salmonella enteritidis, Salmonella paratyphi A, B, C, and Salmonella typhi were deduced after digesting genomic DNA and I-Ceu I and probing with DNA of S. typhimurium; the data indicated strong conservation of rrn gene number and position and genome sizes up to 4950 kb. Digestion of DNA of other bacteria (species of Haemophilus, Neisseria, Proteus, and Pasteurella) suggested that only rrn genes are cut in all these species. I-Ceu I digestion followed by pulsed-field gel electrophoresis is a powerful tool for determining genome structure and evolution.

Base Sequence↗

PubMed1993

The XbaI-BlnI-CeuI genomic cleavage map of Salmonella enteritidis shows an inversion relative to Salmonella typhimurium LT2.

We have established the genomic cleavage map of Salmonella enteritidis strain SSU7998 using pulsed-field gel electrophoresis. The chromosome of 4600 kb was analysed by XbaI (16 fragments), I-CeuI (7 fragments) and BlnI (12 fragments); the genome also contains a plasmid of 60 kb. Cleavage sites of I-Ceul, in the large subunit ribosomal RNA gene, are conserved from Salmonella typhimurium and Escherichia coli K-12, and the XbaI and BlnI sites in glt-tRNA are also conserved, but other sites are less conserved. Transposon Tn10, located at 60 different positions in the chromosome of S. typhimurium, was transduced by bacteriophage P22 into S. enteritidis and the insertion mapped using the XbaI and BlnI sites on Tn10. Gene order in S. enteritidis is identical to S. typhimurium LT2 and similar to E. coli K-12 except for an inversion of 815 kb, which covers the terminus region including T1 and T2. Endpoints are in the NDZs, or non-divisible zones, in which inversion endpoints were not detected in experiments in E. coli K-12 and S. typhimurium LT2. This inversion resembles the inversion between S. typhimurium and E. coli, but is longer at both ends.

Chromosome Inversion↗

PubMed1993

The XbaI-BlnI-CeuI genomic cleavage map of Salmonella typhimurium LT2 determined by double digestion, end labelling, and pulsed-field gel electrophoresis.

Endonuclease digestion of the 4,800-kb chromosome of Salmonella typhimurium LT2 yielded 24 XbaI fragments, 12 BlnI fragments, and 7 CeuI fragments, which were separated by pulsed-field gel electrophoresis. The 90-kb plasmid pSLT has one XbaI site and one BlnI site. The locations of the fragments around the circular chromosome and of the digestion sites of the different endonucleases with respect to each other were determined by excision of agarose blocks containing fragments from single digestion, redigestion with a second enzyme, end labelling with 32P by using T7 DNA polymerase, reelectrophoresis, and autoradiography. Forty-three cleavage sites were established on the chromosome, and the fragments and cleavage sites were designated in alphabetical order and numerical order, respectively, around the chromosome. One hundred nine independent Tn10 insertions previously mapped by genetic means were located by pulsed-field gel electrophoresis on the basis of the presence of XbaI and BlnI sites in Tn10. The genomic cleavage map was divided into 100 units called centisomes; the endonuclease cleavage sites and the genes defined by the positions of Tn10 insertions were located by centisome around the map. There is very good agreement between the genomic cleavage map, defined in centisomes, and the linkage map, defined in minutes. All seven rRNA genes were located on the map; all have the CeuI digestion site, all four with the tRNA gene for glutamate have the XbaI and the BlnI sites, but only four of the seven have the BlnI site in the 16S rRNA (rrs) gene. Their inferred orientation of transcription is the same as in Escherichia coli. A rearrangement of the rrnB and rrnD genes with respect to the arrangement in E. coli, observed earlier by others, has been confirmed. The sites for all three enzymes in the rrn genes are strongly conserved compared with those in E. coli, but the XbaI and BlnI sites outside the rrn genes show very little conservation.

Chromosome Mapping↗

PubMed1993

Location of IS200 on the genomic cleavage map of Salmonella typhimurium LT2.

Locations of six Tn10s, closely linked to each of the six IS200s on the genomic cleavage map of Salmonella typhimurium LT2, were determined by digestion with XbaI and BlnI and separation of the fragments by pulsed-field gel electrophoresis; the locations were then further defined by P22-mediated joint transduction. The orientation of each IS200 with respect to its linked Tn10 was determined by Southern blotting. The locations of IS200-I, IS200-III, and IS200-V were confirmed to be close to sufD, melB, and purC, as previously indicated. IS200-II is jointly transduced with cysG. IS200-IV is near fliA; the linked Tn10 is inserted in fli, making the strain nonmotile. IS200-VI is jointly transduced with aspC but not with aroA. IS200 is transposed to a seventh site in some strains, while remaining in the other six locations described above. These data indicate that genome analysis by pulsed-field gel electrophoresis can locate the positions of Tn10s with accuracy sufficient to predict P22-mediated joint transduction.

DNA Transposable Elements↗

PubMed1992

Xeroderma pigmentosum variant with multisystem involvement.

BACKGROUND: Xeroderma pigmentosum (XP) is a hereditary disorder characterized by recessive inheritance and elevated rates of skin carcinogenesis. There are seven complementation groups (A through G) for which the genetic defect results in a failure to repair DNA damage from UV light and sunlight; one group, the variant, fails to replicate UV-damaged DNA correctly. Patients in XP groups A, B, D, and G have associated neurologic problems, the most severe being known as the DeSanctis-Cacchione syndrome. OBSERVATIONS: We describe a patient with XP from consanguineous parents who has severe multisystem involvement similar to that of the DeSanctis-Cacchione syndrome. Extensive laboratory investigation showed that cells from this patient exhibit DNA replication after irradiation with UV light that is characteristic of the XP variant. The cells also show normal sensitivity to UV light and normal excision repair, consistent with XP variant classification. The presence of the neurologic symptoms is quite unusual in an XP variant. CONCLUSION: Our patient clearly fits into the XP variant category based on normal survival, caffeine toxic reaction, photoproduct excision and repair, and the deficient replication of UV-damaged DNA. This patient seems to be rare, however, among XP variants in displaying severe neurologic symptoms. Because of the consanguineous parents, the possibility that some of this patient's findings are from non-XP-related abnormalities must also be entertained. However, other consanguineous patients with XP variant, eg, XPIOCA, have been described who do not show neurologic abnormalities. In view of the difficulty of defining an XP group from clinical symptoms alone, we urge the term xeroderma pigmentosum variant be used only in the context of the laboratory studies of patients with XP that contain normal repair but deficient semiconservative replication of UV-damaged DNA.

Cell Survival↗

PubMed1991

Facial blanching caused by superpotent corticosteroids.

We present a case of the topical application of a superpotent corticosteroid lotion to the scalp and sideburn area that resulted in facial blanching beyond the site of application. This case demonstrates the need for prudent use of superpotent corticosteroid lotion on the scalp and sideburn area to avoid potential adverse effects.

Administration, Topical↗

PubMed1988

Autosomal dominant keratoderma, ichthyosiform dermatosis and elevated serum beta-glucuronidase.

Five patients in a large pedigree with autosomal dominant palmoplantar keratoderma and/or an ichthyosiform dermatosis were studied. Biopsies of the keratoderma, a remote hyperkeratotic plaque on an arm and the ichthyosis all revealed the same histopathologic changes including hyperkeratosis with round retained nuclei. All 5 patients had elevated serum beta-glucuronidase activity. The significance of beta-glucuronidase in this and other skin diseases is discussed.

Adolescent↗

PubMedDate not supplied

[Psychosocial workload, sick leave, and health-related well being: an empirical study from the perspective of gender research].

PURPOSE: The aim of this study was to test hypotheses on the consequences of gender role expectations with regard to the extent of work stress, selected health-related measures and their associations. METHOD: Data on psychosocial workload (questionnaire of effort-reward imbalance), sick leave (self-reports of the duration of medically certified sick leave during the past two years) and health-related well being were collected in a representative sample of German full-time employees (n = 666). Hypotheses were tested using analyses of variance (ANOVA) and covariance (ANCOVA) and moderated linear regression analyses. RESULTS: Women reported lower health-related well-being as compared to men while effort-reward imbalance and sick leave did not differ between the sexes. Parents reported slightly longer durations of sick leave during the past two years than childless participants (not significant). The results of stratified linear regression analyses show stronger associations between effort-reward imbalance and both health-related measures for women with children than for men with children, while single men and women do not differ in this regard. CONCLUSIONS: Evidence of this kind can be useful for the purposeful planning and implementation of health promotion measures at work. Women with children would be a group deserving special attention. The findings also point to continuing differences in gender role expectations in the family context.

Adolescent↗

PubMedDate not supplied

Somatization symptoms and hypochondriacal features in the general population.

OBJECTIVE: The principal goal of this study is to examine the base rates of somatoform symptoms and of hypochondriacal features in the general population. METHODS: A representative sample of 2050 persons in Germany was examined by use of screening for somatoform symptoms and the Whiteley Index. RESULTS: The most frequent somatoform symptoms were back pain, joint pain, pain in extremities, and headache, as well as abdominal symptoms (bloating or intolerance of several foods) and cardiovascular symptoms (palpitation). People reported a mean of two somatization symptoms of DSM-IV somatization disorder (SD) during the prior 2 years. Strong age and medium gender effects were found for most somatoform symptoms, as well as for composite indices. However, the sex ratio suggested in DSM-IV for SD seems to be an overestimation. Hypochondriacal features showed only small sex differences but, again, pronounced age effects. In contrast to low rates for SD, the base rates for somatization and hypochondriacal features were high and represented the health care relevance of subthreshold syndromes. CONCLUSION: We present base rates of hypochondriacal and somatization features that may be important facets in the development of classification criteria and in the interpretation of health care expenditure.

Adolescent↗