Search PubMed⌕ Search

Biomedical subjects

M Simon

Publications and source records attributed to M Simon.

At least 667 records · Page 37Linked to original sources
PubMed1978

Identification of the structural gene for the hook subunit protein of Escherichia coli flagella.

Previous studies showed that the structural gene for the flagellar hook subunit protein (molecular weight 42,000) was one of a group of flagellar genes located on the Escherichia coli genome near pyrC. Several lines of evidence indicate that the flaK gene is the structural gene for the hook subunit protein. Fla+ strains that were insensitive to chi infection could be isolated as revertants of an FlaK- amber mutant strain but from no other Fla- strain. The hook subunit proteins isolated from such chi-sensitive revertants of the FlaK- strain were shown to be antigenically and electrophoretically different from the hook protein isolated from the wild-type strain. Thus, reversion of a mutation in the flaK gene resulted in alteration of the structure of the hook protein. Furthermore, in programming experiments with hybrid lambda containing flagellar genes, lambdafla with flaK genetic activity programmed the synthesis of a 42,000-molecular weight protein, whereas lambdafla without flaK genetic activity did not.

Bacterial Proteins↗
PubMed1978

Genes for the hook-basal body proteins of the flagellar apparatus in Escherichia coli.

Of the more than 30 genes required for flagellar function, 6 are located between pyrC and ptsG on the Escherichia coli genetic man. This cluster of genes is called flagellar region I. Four-point transductional crosses were used to establish the position and order of the region I flagellar genes with respect to the outside markers ptsG and pyrC. Bacteriophage lambda-E. coli hybrids that contained most of the genes necessary for flagellar formation were constructed. The properties of specific hybrids that carried the region I fla genes were examined by genetic complementation and by measuring the capacity of the hybrids to direct the synthesis of specific polypeptides. The results of these tests with lambda hybrids and with a series of deletion mutations derived from the lambda hybrids demonstrated the existence of at least six flagellar-specific cistrons. These directed the synthesis of polypeptides with the following apparent molecular weights: flaV, 11,000; flaK, 42,000; flaL, 30,000 and 27,000; flaM, 38,000; flS, 60,000; and flaT, 35,000. Plasmid ColE1-E. coli hybrids with region I flagellar genes were also used to program the synthesis of polypeptides in minicell-producing strains. The polypeptides synthesized in these experiments were identical to polypeptides of the hook-basal body structure and helped to confirm the assignment of genes to specific polypeptides. The synthesis of all of these polypeptides was regulated by the same mechanism that regulates the synthesis of other flagellar-related structural components.

Bacterial Proteins↗
PubMed1978

Serum and tumour ferritins in primary liver cancer.

Serum ferritin concentrations were found to be raised, often considerably, in 58 of 76 black patients with primary liver cancer (PLC). No correlation could be demonstrated between the serum ferritin concentration and several other measurements, including the following: hepatic iron stores measured chemically, the size of the tumour, serum transaminase values, and the presence or absence of cirrhosis in the non-tumorous liver. There was, however, a negative correlation between serum ferritin and alpha-foetoprotein concentrations. Ferritin was purified from PLC tissue obtained from three patients at necropsy and the distribution of isoferritins was determined by isoelectric focusing. Acidic isoferritins similar to those previously found in PLC tissue were obtained. Their acidic nature was confirmed chromatographically using DEAE cellulose. Because the serum ferritin in patients with PLC probably consists of a mixture of normal and acidic isoferritins, it is likely that the serum assay used in the present study underestimated the actual concentrations present. With the development of an assay which utlises a specific antibody against acidic PLC isoferritins, serum ferritin may prove to be a second marker for PLC.

Adult↗
PubMed1978

Hypovitaminemia A in idiopathic hemochromatosis and hepatic cirrhosis. Role of retinol-binding protein and zinc.

Serum levels of vitamin A, its specific carrier protein retinol-binding protein (RBP), and zinc were determined in 34 cases of idiopathic hemochromatosis, 33 cases of alcoholic cirrhosis, 10 cases of non-alcoholic cirrhosis, and in 35 normal controls. In both alcoholic and non-alcoholic cirrhosis, vitamin A and RBP levels were very significantly reduced, whereas a significantly low zinc was observed only in the alcoholic cirrhosis group. In idiopathic hemochromatosis, vitamin A values were significantly lower compared to normals, whereas serum RBP levels were normal and serum zinc was very close to that of the controls. A significant correlation was found between vitamin A and RBP levels in the entire group of 112 patients. These results, (1) in alcoholic and non-alcoholic cirrhosis, confirm a dramatic vitamin A deficiency and the major role played by decreased RBP, but tend to deemphasize the possible role of zinc deficiency; (2) in idiopathic hemochromatosis, affirm a significant serum vitamin A deficiency supposedly by a different mechanism from that of alcoholic cirrhosis since in idiopathic hemochromatosis plasma RBP levels are normal. The role of this vitamin A disorder should be considered in the interpretation of clinical signs of idiopathic hemochromatosis such as ichthyosis and visual disorders.

Adult↗
PubMed1978

Ascorbic acid status in idiopathic hemochromatosis.

Vitamin C status was studied, by means of leucocyte ascorbic acid concentrations, in 67 cases of idiopathic hemochromatosis subdivided into 44 untreated and 25 treated cases (2 patients belonging to both subgroups) and compared to 31 normal subjects and 37 alcoholic cirrhosis patients. The control groups exhibited the following mean levels (+/- SEM): 34.4 +/- 1.9 microgram/10(8) WBC in normals and 22.0 +/- 1.8 microgram/10(8) WBC in alcoholic cirrhosis. In idiopathic hemochromatosis the mean levels were: for the untreated group 19.5 +/- 1.7 microgram/10(8) WBC and for the treated group 34.3 +/- 2.3 microgram/10(8) WBC. These results (1) affirm an important vitamin C deficiency in the untreated disease; (2) suggest that iron overload is the main causal factor in view of the striking difference--to date unreported--between untreated and treated cases of idiopathic hemochromatosis. Besides its possible theoretical interests, this vitamin C deficiency is responsible in idiopathic hemochromatosis for a significant underestimation of the desferrioxamine-induced urinary iron excretion.

Adult↗
PubMed1978

[Heat stroke and disseminated intravascular coagulation. Apropos of 2 cases].

Two cases of fatal heat stroke, concerning a 20 year-old soldier and a 44 year-old psychiatric patient, treated with neuroleptics, are reported. The clinical picture, starting suddenly with coma and hyperthermia, was quite identical for both. Secondarily, while hyperthermia decreases and the conscience improved partially, an hemorrhagic syndrome similar to a consumption coagulopathy, acute renal insufficiency and acute hepatic failure appear. Death occurred after aggravated neurological disorders and respiratory distress. The anatomical lesions spread on all the viscera include tubular nephritis, and hepatic centro-lobular necrosis and an interstitial and alveolar oedema with hemorrhages and hyaline membranes in the lungs.

Acute Kidney Injury↗
PubMed1978

Effect of neonatal corticoid treatment on tryptophan and serotonin metabolism.

Glucocorticoid administration to newborn rats leads to the premature induction of hepatic tryptophan oxygenase. This is accompanied by a retardation of the developmental increase in brain serotinin both in regions of serotoninergic cell bodies and in terminal projection areas. The magnitude of the fall in serotonin is relatively small. This appears due, at early ages to the concomitant induction of brain tryptophan hydroxylase and at late periods to retarded development of the blood brain barrier against tryptophan.

Animals↗
PubMed1978

[Genetically conditioned variability of metabolic profile parameters in dairy cows].

Individual heritability and differences in the concentration of the chemical components of the blood were studied in the dairy cows of the Slovak Spotted breed. The experiment was performed with 166 cows. The set comprised six groups of half-sisters from three stocks. The differences among the cows were statistically significant (alpha = 0.01) in the majority of the parameters studied: haematocrit, haemoglobin, pH, PO2, oxygen saturation of the blood; plasma potassium, phosphorus, magnesium, calcium, total protein, urea, glucose, alkaline phosphatase, and esterified fatty acids. The coefficients of repeatibility for the mentioned parameters ranged from 0.19 to 0.75. The heritability coefficients were calculated for the parameters in which the inter-group differences were significant: total protein (0.62), magnesium (0.57), potassium (0.51), urea (0.49), glucose (0.45), phosphorus (0.43), calcium (0.39), haematocrit (0.37), haemoglobin (0.35), pO2 (0.29). The results suggest that some of the parameters under study are under certain genetic control.

Animals↗
PubMed1978

[The cardiomyopathy of idiopathic hemochromatosis].

A retrospective study of the case histories of 216 patients with idiopathic haemochromatosis has highlighted the frequency of cardiac involvement in this condition (53%). Two forms can be distinguished: a latent one (65%), in which the changes are predominantly electrocardiographic, and a clinical form (35%) with the features of congestive cardiomyopathy, notable for the rapidity of onset after right heart failure, the degree of cardiomegaly, the constant finding of abnormalities of ventricular repolarisation, the relative frequency of latent disorders of supra-His atrio-ventricular conduction, and the finding of elongation of the isovolumic contraction time on the phonomechanocardiogram. A haemodynamic profile is the same as for non-obstructive hypotonic cardiomyopathies, and is usually associated with a slow rise in left ventricular pressure. The cardiomyopathy, which is the most frequent cause of death, determines the prognosis in this condition. It may be found in association with diabetes and gonad failure. The finding of cardiomyopathy indicates basic treatment by veresection, which may be the only means of establishing a favourable outcome.

Adult↗
PubMed1977

Idiopathic hemochromatosis. Demonstration of recessive transmission and early detection by family HLA typing.

We studied iron overloading and HLA types in 24 sibships of patients with idiopathic hemochromatosis, of which 15 had at least two subjects with overt forms. HLA types of 84 unrelated patients were also investigated. Among siblings there was a significant association (P less than 0.0001) between the presence of hemochromatosis and the possession of the same two HLA haplotypes. The fact that overt forms of hemochromatosis depend on the presence of two specific homologous chromosomes strongly supports a recessive mode of transmission for the overt disease. The haplotypic equilibrium demonstrated in the unrelated patients group is another supporting argument. The lod-score value (2.239 for theta = 0.005) in six families available for study further supports the conclusion that a hemochromatosis gene is closely linked to the HLA-A locus. HLA typing in families with hemochromatosis could provide a means of early detection of subjects at risk before appearance of any sign of iron overload.

Adult↗
PubMed1977

Recombinational switch for gene expression.

Flagellar antigens are specified by two genes, H1 and H2. The expression of these genes is regulated such that only one gene activity, or phase, is expressed at a given time. Molecular cloning techniques were used to isolate the segments of Salmonella DNA which contain these genetic loci. Heteroduplex analyses revealed an anomaly in the cloned fragment, that is, and apparent inversion, which was shown to be adjacent to the H2 gene. A correlation was demonstrated between the phase state of the H2 gene and the sequence of the adjacent segment. We propose that an inversion of this region is the phase-determining event in flagellar gene expression in Salmonella.

Antigens, Bacterial↗