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Biomedical subjects

H Mayer

Publications and source records attributed to H Mayer.

At least 253 records · Page 14Linked to original sources
PubMed1982

The effect of Pseudomonas aeruginosa on the immunogenicity of enterobacterial common antigen.

Pseudomonas aeruginosa produces a factor (PF) which alters the enterobacterial common antigen (ECA). Its effect on the immunogenicity of two types of immunogenic ECA, namely, the ethanol-soluble preparation freed of lipopolysaccharide and the LPS-coupled form from the R-mutant E. coli 014 was investigated. The antibody response following intravenous immunization was determined by means of the hemagglutination test. It is shown that PF abolishes the immunogenicity of the former but not of the latter. PF obtained from a strain of P. maltophilia yielded the same results. Antiserum against Pseudomonas aeruginosa of types 1 and 6 neutralizes PF produced by either type. These results suggest that PF alters the lipid part and not the haptenic determinant of ECA and that this activity is neutralized by P. aeruginosa antiserum of either type 1 or type 6. This interpretation is compatible with the identification of PF as a lipase.

Animals↗
PubMed1981

The effect of several nucleic acid binding drugs on the cleavage of d(GGAATTCC) and pBR 322 by the Eco RI restriction endonuclease.

The endonucleolytic action of the EcoRI restriction enzyme on the double-stranded oligonucleotide d(GGAATTCC) and the supercoiled plasmid DNA pBR 233 is inhibited by actinomycin D, ethidium bromide, proflavin, distamycin A and netropsin. Half-maximal inhibition is observed at around 100 microM concentrations for the intercalating drugs, and around 0.1 to 1 microM concentrations for netropsin and distamycin A. The inhibitory activity of these drugs can be correlated with their affinity to the oligonucleotide and the plasmid DNA. Since at high concentrations of the drugs a complete inhibition is observed, it is concluded that the effect of the drugs on the stereochemistry of the EcoRI site is such that recognition is excluded.

Circular Dichroism↗
PubMed1981

Restriction endonuclease EcaI from Enterobacter cloacae.

Restriction endonuclease EcaI obtained from Enterobacter cloacae DSM30056 recognizes the group of heptanucleotide palindromes 5'-G[unk]G-T-N-A-C-C-3', and on cleavage (arrow) produces fragments with 5'-terminal pentanucleotide extensions. It is identical in specificity with restriction endonuclease BstEII from Bacillus stearothermophilus ET.

Base Sequence↗
PubMed1981

ClaI. a new restriction endonuclease from Caryophanon latum L.

From Caryophanon latum L site specific restriction endonuclease (ClaI) has been purified, which recognises tha DNA hexanucleotide palindrome 5'-A-T-C-G-A-T-3'. Staggered cleavage generates DNA restriction fragments with 5'-terminal pCG extensions. A CLaI map of bacteriophage lambda has been determined, which indicates cleavage inhibition due to adenine methylation at over lapping ClaI-GATC recognition sequences. Plasmid pBR322 is cut only once, in the tetracycline promoter region, and can, therefore, be used as a vector system for cloning fragments derived from ClaI digestions, and in addition for fragments generated by TaqI, HpaII, and several other enzymes.

Bacteriophage lambda↗
PubMed1981

Structures of the glycopeptidolipid antigens from serovars in the Mycobacterium avium/Mycobacterium intracellulare/Mycobacterium scrofulaceum serocomplex.

The 'C-mycosidic' glycopeptidolipid typing antigens from all serovars in the Mycobacterium avium/M. intracellulare/M. scrofulaceum complex have been examined to varying extents. Detailed analysis of those from serovars 8, 9, 16 and 25 show that the antigens consist of short acetylated oligosaccharides linked to a common fattyacyl-peptidyl-O-(3,4-di-O-methylrhamnose) 'core'. The oligosaccharide units, in a form suitable for chemical studies, were liberated as oligosaccharide alditols on treatment of the glycopeptidolipids with alkaline borohydride solution. The alditol in the reduced oligosaccharides from all sources is 6-deoxytalitol. Moreover rhamnose is also always present, indicating that a 'basal' disaccharide, rhamnosyl-6-deoxytalosyl, is always linked to the allo-threonine in the acylpeptide. In addition the oligosaccharides from the glycopeptidolipids of each serovar are distinguished by their own individualistic sugars: 3-O-methylglucose in serovar 8; 2,3-di-O-methylfucose in serovar 9; 2-O-methylfucose in serovar 25; 4-O-methylrhamnose in the oligosaccharide from one of the two glycopeptidolipids in serovar 16 and apparently another rhamnosyl substituent in the other oligosaccharide. The glycopeptidolipid antigens in their structural principals, cellular location and physiological role bear a striking miniscule resemblance to cell wall components of other bacteria such as the O-antigenic and R-antigenic lipopolysaccharides.

Antigens, Bacterial↗
PubMed1981

Effect of proteins on the immunogenicity of enterobacterial common antigen.

Enterobacterial common antigen isolated by two independent extraction procedures was found to precipitate with a number of basic or hydrophobic proteins. Complexes of enterobacterial common antigen with protamine sulfate, with methylated bovine serum albumin or with a fraction of outer membrane proteins of two different Shigella wild types proved to be highly immunogenic in rabbits upon intravenous immunization, in contrast to the enterobacterial common antigen preparations by themselves. This explains why crude isolates of enterobacterial common antigen usually are good immunogens in contrast to the isolated antigen, which was described to be either not or only very poorly immunogenic.

Antibodies, Bacterial↗
PubMed1981

Structure of the heptose region of lipopolysaccharies from Rhodospirillum tenue.

There is a common structure (core region) in the lipopolysaccharides of Rhodospirillum tenue. It is composed of a branched trisaccharide of L-glycero-D-mannoheptose (and of 2-keto-3-deoxyoctonate), as revealed by methylation analyses of degraded polysaccharides of four different R. tenue strains. The structure is similar or might even be identical to the inner core of enterobacterial O antigens. In addition, each of the four R. tenue lipopolysaccharides contains a strain-specific region that consists of heptose(s) (L-glycero-D-mannoheptose or D-glycero-D-mannoheptose or both) or hexoses. There is a partial substitution of the core region and the strain-specific region by phosphorus, showing microheterogeneity.

Chemical Phenomena↗
PubMed1981

Localization of enterobacterial common antigen in Yersinia enterocolitica by the immunoferritin technique.

Rabbits were immunized with the enterobacterial common antigen (ECA)-immunogenic strain Escherichia coli F470. ECA-specific antiserum was obtained by absorbing the resulting antisera with the genetically closely related ECA-negative strain E. coli F1283. These two strains also served as positive and negative controls in the localization study of ECA in Yersinia enterocolitica strain 75, smooth and rough forms (Ye75S and Ye75R), by the indirect immunoferritin technique. Cells of Ye75S grown at 22 degrees C showed no labeling with ferritin after treatment with the ECA-specific antiserum and subsequent ferritin-conjugated goat anti-rabbit antibodies. If the cells were grown at 40 degrees C, however, most of the cells showed weak ferritin labeling. At this higher growth temperature, the lipopolysaccharide of this strain contains less O-specific chains (6-deoxy-L-altrose), as was shown in a previous study. The rough mutant Ye75R, which lacks O-specific chains completely, showed denser labeling with ferritin. These results indicate that ECA on the cell surface of Ye75S is covered by O-specific chains of the lipopolysaccharide if grown at 22 degrees C and is therefore not accessible to ECA antibodies. It becomes accessible, however, when O-chains are lacking (R mutants) or when they are reduced in size or amount (growth at 40 degrees C).

Antigens, Bacterial↗
PubMed1981

Plasma C-peptide and insulin in trained and untrained subjects.

Plasma insulin and C-peptide were simultaneously determined under various conditions in 11 endurance-trained athletes and 12 nonathletes. Both groups performed an exhaustive ergometer test and an endurance test with 38% of the maximal achieved work load for 45 min. An intravenous glucose tolerance test was also performed. In the basal state, athletes had low plasma insulin and C-peptide concentrations. During exercise, insulin and C-peptide decreased similarly in both groups. In the recovery period, insulin and C-peptide rose within a few minutes. There were differences between the extent as well as the time course of this "rebound" effect after exhaustive or endurance exercise that might be related to glucose alterations. The insulin response but not the C-peptide response after glucose injection was blunted in trained subjects. Results indicate that basal plasma insulin concentrations are lower in athletes due to reduced insulin secretion. During exercise, insulin secretion is diminished independent of the training state. The blunted response of insulin after glucose administration in athletes is due to an enhanced plasma clearance.

Adult↗
PubMed1980

Binding of non-substrate nucleotides to a restriction endonuclease: a model for the interaction of bam HI with its recognition sequence.

The kinetic constants of the site-specific endonuclease Bam HI for various substrates were determined and binding of non-substrate nucleotides to the enzyme was studied. Agarose gel assays in combination with an integrated Michaelis-Menten equation were used for the evaluation of data. The turnover number was 2.2 min-1 at 37 degrees C with pJC80 DNA as the substrate. It depends on the conformation and base composition of the substrate. Michaelis constants also depend on substrate conformation. Non-substrate polynucleotides were found to inhibit Bam competitively with KI ranging from 10(-6) to > 10(-3) M depending on base composition, base pairing, and helix conformation. Dinucleotides showed sequence-specific, competitive inhibition with KIs ranging from 10(-5) to > 10(-3) M. Mononucleotides and -nucleosides acted noncompetitively. Binding was influenced by the extent of phosphorylation, but not by the nature of the base. KIs varied between 10(-3) and 10(-2) M. The results are discussed with respect to the recognition requirements of Bam HI.

Bacteriophage lambda↗
PubMed1980

[Surgical treatment of glaucoma].

Normalization of intraocular pressure in primary open-angle glaucoma and narrow-angle glaucoma by single iridencleisis was demonstrated in 551 eyes between six months and seven years postoperatively. Of the eyes followed up in our clinic, 80% were normalized by operation, another 18.8% by operation and additional miotics and 1.2% after a second operation. On the other hand, of the eyes followed up externally, the corresponding figures were 69.3%, 25.2% and 4.5%, respectively. Because of the low complication rate in respect of secondary cataract, visual field defects and late infections, we maintain the view that single iridencleisis is an excellent intervention for the treatment of glaucoma.

Follow-Up Studies↗
PubMed1980

Structural studies on the glucose-heptose region of the Proteus mirabilis R core.

Methylation analysis of the core oligosaccharide of the Proteus mirabilis mutant R4 (derived from serotype 028 was carried out in order to obtain information on the internal (glucose-heptose) region of the P. mirabilis R core. The isolated core oligosaccharide was composed of glucose, L-glycero-D-manno-heptose, 3-deoxy-D-manno-octulosonic acid (dOclA) and phosphorus in a molar ratio of about 1:2:1:1.4. It was methylated either directly or after dephosphorylation. To localize the position of the phosphate substituents, the permethylated product was dephosphorylated with hydrogen fluoride and the oligosaccharide obtained was remethylated using C2H3I. Location of phosphate at C-7 of the terminal heptose was shown by isolation of the sugar phosphate from partial hydrolysates and gas-liquid chromatography/mass spectrometry of the permethylated product. Combining the data of the methylation analysis with the data of an NMR study allows one to formulate the structure of the core oligosaccharide as folllows: (formula: see text).

Carbohydrate Conformation↗
PubMed1980

Localization of enterobacterial common antigen:immunogenic and nonimmunogenic enterobacterial common antigen-containing Escherichia coli.

In rabbits immunized with intact bacteria, the immune response to the enterobacterial common antigen (ECA) predominantly consists of the production of immunoglobulin M antibodies. This is not dependent on whether the animals are immunized for a short (2 weeks) or a long (3 months) period of time. The highest ECA-specific immunoglobulin G titers were observed after a short immunization with living bacteria. ECA-specific antisera were obtained by absorption with appropriate ECA-negative mutants. The absorbed antisera were then separated on Sephadex G-200. The resulting immunoglobulin G fractions were conjugated to ferritin by glutardialdehyde and used to visualize the distribution of ECA in E. coli. Bacterial strains either possessing the immunogenic form of ECA (F470, 2387) or solely the nonimmunogenic form (F614) or being devoid of both (ECA-negative mutants F1283 and F1327) were labeled with the conjugates. Freezeetchings of ferritin-labeled strains showed a dense labeling of the outer membrane in case of ECA-immunogenic strains, an essentially weaker labeling of the non-immunogenic ECA mutant and, as expected, no labeling of ECA-negative mutants. Comparable results were obtained with the indirect immunofluorescence technique: the whole cell envelope of strain F470 showed a brilliant fluorescence, whereas a much lesser, spotty distribution of fluorescence was noted with strain F614 and none at all was noted with the ECA-negative strains. These data show that ECA is localized in the outer membrane of ECA-containing strains and further demonstrate that there is more in the immunogenic strains than in the nonimmunogenic ones.

Animals↗
PubMed1980

Localization of enterobacterial common antigen: Proteus mirabilis and its various L-forms.

An investigation of Proteus mirabilis wild-type strains and their various derived L-forms shows that the enterobacterial common antigen (ECA) is localized in the outer membrane of the cell envelope of these strains. In strains where the outer membrane is lacking (stable protoplast L-forms) or where its amount is reduced (spheroplast UL19) no ECA or only reduced amounts of it are detected by serological tests or by ferritin-labeling techniques.

Antigens, Bacterial↗
PubMed1980

Restriction endonucleases or the site-specific DNA endonucleases.

Our present view of the site-specific endonucleases, which appear to be ubiquituous in the prokaryote kingdom, is probably heavily distorted by our search for tools for recombinant DNA technology. Only those enzymes having recognition sequences in the range of three to seven specific bases have been isolated. Of course the usefulness of these enzymes in the analysis of complex genomes, the rise of "reverse genetics", and the immediate breakthroughs in the area of gene expression in eukaryotes, particularly the understanding of tumour virus RNA processing and gene rearrangements in the expression of immunoglobulin genes has dominated the consciousness of the molecular and cell biologists during the last five years. There is a great diversity of staggering, symmetry, asymmetry and degeneration in the recognition sequences found. Taking into account also the genetic data on site-specific recombination and/or DNA degradation suggests that our present collection of endonucleases may only represent a narrow spectrum of specificities on an open-ended scale of complexity. The enzymes, themselves provide a rich pool to be exploited by the biophysicist and the biochemist to probe the subtleties of DNA-protein interaction.

Binding Sites↗