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Biomedical subjects

M Simon

Publications and source records attributed to M Simon.

At least 595 records · Page 33Linked to original sources
PubMed1981

Sensory transducers of E. coli are encoded by homologous genes.

The tsr and tar genes, which are widely separated in the E. coli genome, encode functionally analogous transducer proteins that focus and integrate two distinct classes of chemosensory information. Physical mapping of these genes was achieved by use of transposon Tn5 mutagenesis of cloned DNA fragments. The polar effects of Tn5 insertions in the tar-cheR-cheB-cheY-cheZ region indicated that these genes are cotranscribed from a promoter upstream of tar and revealed the existence of a new gene, tap (taxis-associated protein), lying between tar and cheR. DNA hybridization studies demonstrated that the tsr gene possesses sequence homologies with the tar and tap genes, suggesting that they have all evolved from a common ancestor. The tap gene encoded a polypeptide of apparent molecular weight of 65,000, which may constitute a transducer protein of unknown specificity.

Bacterial Proteins↗
PubMed1981

Characterization of two mutant strains of Saccharomyces cerevisiae deficient in coproporphyrinogen III oxidase activity.

Two new haem-deficient mutants of Saccharomyces cerevisiae were isolated on the basis of their catalase deficiency. Mutant H11 accumulated and excreted coproporphyrin III and was completely deficient in haem; the cell-free extract had no coproporphyrinogen oxidase activity. Mutant H12 accumulated uroporphyrin to coproporphyrin III and excreted coproporphyrin III, and contained a small amount of haem; the cell-free extract had a residual coproporphyrinogen oxidase activity. The two mutations were allelic and the mutant phenotypes were under the control of a single, recessive nuclear gene.

Coproporphyrinogen Oxidase↗
PubMed1981

Homology between the invertible deoxyribonucleic acid sequence that controls flagellar-phase variation in Salmonella sp. and deoxyribonucleic acid sequences in other organisms.

The invertible deoxyribonucleic acid (DNA) segment cloned from Salmonella sp. was radioactively labeled and used as a probe to search for homologous sequences by Southern hybridization. Only one copy of the invertible segment could be found on the Salmonella sp. genome. Partial sequence homology with the invertible region was detected in bacteriophage Mu and P1 DNA by low-stringency hybridization. Under these conditions, no homology was detected with Escherichia coli DNA. A strain of Salmonella sp. defective in phase variation carrying the vH2- allele was also analyzed by DNA-DNA hybridization. The results show that there is sequence divergence between diphasic and vH2- strains within the invertible sequence.

Bacterial Proteins↗
PubMed1981

Computerized radiologic reporting with voice data-entry.

The accurate, voice entry of radiologic reports into a computer takes significantly longer than entry by keyboard. Careful speech and considerable patience are required to avoid an unacceptably high error-rate. With improvements in the future, this technology may compete with the conventional technology.

Computers↗
PubMed1981

Assessment of liver iron content in 271 patients: a reevaluation of direct and indirect methods.

Two direct methods for hepatic iron assessment (liver iron concentration and stainable liver iron--judged by a new histologic grading) and three indirect methods (serum iron and transferrin saturation, deferoxamine-chelation test, and ferritinemia) were reevaluated in 271 patients. These patients consisted of: 103 with idiopathic hemochromatosis, 39 with alcoholic cirrhosis, 54 with noncirrhotic alcoholic liver diseases, 13 with nonalcoholic liver diseases, and 62 with miscellaneous disorders. The results indicate that: (a) liver iron concentration, well correlated with mobilized excess iron (r = 0.88; p < 0.01), is the method of reference and validates the proposed histologic grading; (b) serum ferritin, which is in good correlation with liver iron concentration (r = 0.80; p < 0.01), is a valuable indirect method for hepatic iron evaluation; (c) regarding the other indirect methods a "boundary zone" may be delimited, thus corresponding to liver iron concentration values of 10.7 mumol/100 mg dry liver weight, beyond which values of serum iron less than 28.6 micrometer or transferrin saturation less than 45% or chelatable iron less than 45 mumol/24 h are rare; and (d) using the various indirect methods, there is a marked risk in idiopathic hemochromatosis to underestimate and in alcoholic liver diseases to overestimate hepatic iron content.

Deferoxamine↗
PubMed1980

[Clinical field study on the frequency and topographical distribution of lichen ruber including the question of etiological influence factors].

A total of 374 Patients with lichen ruber of skin and/or mucous membranes, treated at our Department during a period of 7 years, have been studied retrospectively. The prevalence rate, the distribution pattern as well as the dependence on localisation of different types of clinical lesions have been examined. In 54% of the cases studied, the oral mucosa was involved, in about half of these cases without any other manifestation. In 92 hospitalised patients, a statistically significant correlation between lichen ruber and chronic hepatic disorders was revealed. On the other hand, chronic alcoholism and/or smoking habits did not show any close correlation with lichen ruber.

Adolescent↗