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Biomedical subjects

R Mayer

Publications and source records attributed to R Mayer.

At least 271 records · Page 15Linked to original sources
PubMed1983

Sensitive fluorometric determination of plasminogen activator in cell lysates and supernatants.

A fluorogenic substrate for plasmin, CBZ-Gly-Pro-Arg-AEC, has been synthesized and used to develop a new sensitive photometric and fluorometric assay of plasminogen activator activity. The fluorescence intensity of free AEC at 460 nm is about 3 orders of magnitude higher than that of acyl-AEC. The release of AEC from the peptidyl derivative was monitored fluorometrically after extraction of free AEC in ethylacetate. Under such conditions, the Km was 0.16 mM. This method was used to monitor the activity of plasminogen activator synthetized by fibroblastic cells (BHK 21 C 13) either released in the supernatants or cell-associated.

Animals↗
PubMed1983

Interactions of the 26-39 fragment of the cro protein from lambda bacteriophage with nucleic acids.

A tetradecapeptide with a sequence identical to residues 26-39 of the cro protein from bacteriophage lambda has been synthesized. This peptide has no secondary structure in an aqueous buffer but adopts an alpha-helical conformation in the presence of 20% hexafluoroisopropanol. The fluorescence of the single tyrosyl residue of the cro protein fragment is quenched upon binding to nucleic acids. Proton magnetic resonance has been used to investigate complex formation of the cro protein fragment with a self-complementary decadeoxynucleotide d(AATTGCAATT). Changes in resonance positions and linewidths have been observed for both partners in the 4 complexes which are obtained when either the single-stranded or double-stranded oligonucleotide is mixed with either the random coil or the alpha-helical peptide. These studies are presently extended to the specific complex formed by the cro protein fragment with the OR3 operator sequence.

Bacteriophage lambda↗
PubMed1983

[Hairy nasopharyngeal polyp as a respiratory emergency].

Respiratory distress and a total airway obstruction in an newborn was caused by a mobile tumour in the pharynx. Urgently it had to be fixed with holding suture under traction. Surgical resection revealed a bipartial hairy tumour based on the lateral pharyngeal side of the soft palate. The histologic examination showed: fat tissue, cornified epidermis and sebaceous glands, but no further signs of teratoma. Further complications as Pneumothorax and necrotising entercolitis could be managed.

Emergencies↗
PubMed1981

The phosphoenolpyruvate-dependent carbohydrate: phosphotransferase system enzymes II as chemoreceptors in chemotaxis of Escherichia coli K 12.

In Escherichia coli K12, eight substrate-specific, membrane-bound enzymes II of the PEP-dependent carbohydrate: phosphotransferase system (PTS), specific for hexoses, hexosamines and hexitols, have been characterised in a series of isogenic and constitutive strains. In such mutants, lacking all but one enzyme II, the transport and vectorial phosphorylation activities as well as the chemotactical response in capillary tube assays have been compared. According to the data obtained, all enzymes II not only are directly involved in the transport and vectorial phosphorylation of their substrates, but they have also a primary role as the chemoreceptors for these substrates: (1) Metabolism of the attractant beyond the phosphorylation step is not a pre-requisite to eliciting positive chemotaxis. (2) Mutants, having only one enzyme II react in the capillary tube assay only to substrates of this enzyme II, but not to substrates of the missing enzymes II. This holds for enzymes II consisting of one membrane-bound protein as well as for systems containing a soluble factor III (FIII). (3) The substrate specificities or affinities, whether tested by transport and chemotaxis assays in vivo or by phosphorylation tests in vitro, are in correspondence. (4) The activities of enzymes II, regulated in a complex way at the level of enzyme synthesis and activity and tested as above, are also in agreement, (5) Mutants lacking the soluble proteins enzyme I or HPr of the PTS no longer respond chemotactically to any substrate taken up and phosphorylated by enzymes II. It is concluded that in PTS enzymes II some functions required for transport and chemotaxis are identical. It is suggested furthermore, that the alternation of intrinsic membrane-bound proteins between a phosphorylated and a dephosphorylated state, rather than binding of the substrate to the enzyme II, is the decisive stimulus in the chemotaxis toward carbohydrates taken up by these transport systems.

Bacterial Proteins↗
PubMed1981

Correlation of Plasma CEA and CEA tissue staining in poorly differentiated colorectal cancer.

A review of patients operated on for colorectal cancer disclosed poorly differentiated histologies in those whose preoperative and postoperative carcinoembryonic antigen (CEA) levels were no elevated, even in the presence of metastatic disease. CEA was therefore, of little prognostic value or predictive of disease recurrence in these patients. The amount of CEA in tumor tissue of 17 patients with poorly differentiated colorectal cancer was estimated with the immunoperoxidase staining technique and was correlated with histology and plasma CEA levels obtained during various stages of disease. Five tumors did not stain negatively for CEA and all had predominantly poorly differentiated histologies. In all of these patients metastatic disease developed but not elevated plasma CEA levels. In contrast 12 tumors stained positively for CEA and were found to contain either differentiated areas or signet ring cells. Serial plasma CEA levels correctly monitored the postoperative course of all 12 patients. Six of these had a relapse and all were detected by serial increases in plasma CEA. The remaining six were disease free greater than 48 months after resection and had normal plasma CEA levels. Among poorly differentiated tumors, those that contain glandforming areas or signet ring cells can be assumed to produce CEA and plasma CEA levels can be used effectively for monitoring. On the other hand, undifferentiated tumors which do not stain for CEA identify those patients whose plasma CEA levels do not provide a useful monitor.

Adenocarcinoma↗
PubMed1981

Synthesis and structural studies of a self-complementary decadeoxynucleotide d(AATTGCAATT). I.-Synthesis and chemical characterization of the decanucleotide.

The synthesis of the self-complementary decadeoxynucleotide d(AATTGCAATT) is described. The phosphotriester method has been used with several modifications. Protected nucleotides have been prepared in a one-step reaction involving a new monofunctional phosphorylating agent: p-chlorophenyl-beta-cyanoethyl phosphate. Triethylammonium salts of mononucleoside 3'-phosphodiesters were obtained either by decyanoethylation of the triesters or, in the case of thymine, by a one-step reaction starting from 5'-0-methoxytritylthymidine and the mixture pyridine-para-chlorophenyl-methyl-phosphorobromidate. The usual coupling reactions were then used to prepare the decadeoxynucleotide in large quantities.

Chemical Phenomena↗
PubMed1981

Synthesis and structural studies of a self-complementary decadeoxynucleotide d(AATTGCAATT). II.-Proton magnetic resonance studies.

Proton magnetic resonance spectra of the self-complementary decadeoxynucleotide d(AATTGCAATT) at 90 and 250 MHz have been obtained at different temperatures. The assignment of the different resonance lines to the base protons was obtained by combining the data derived from various methods: hydrogen in equilibrium with deuterium exchange at the H8 position of purines; comparison of NMR spectra obtained at high temperature with those of mononucleotides; comparison of the variations in chemical shifts obtained between 280 K and 360 K with calculated values; determination of half-transition temperatures for each base pair. On the basis of computed chemical shifts for stacked base-pairs it is concluded that the decadeoxynucleotide duplex exists in the B form in solution at 280 K. Propagation of the opening of the mini double helix from terminal to central base pairs if reflected in the variation of half-transition temperatures which vary between 306 K and 327 K.

Chemical Phenomena↗
PubMed1981

[Networking, an alternative model of community empowerment.].

After a brief critical analysis of some of the limitations of community psychiatry, the authors give an historical review of the social psychiatric network and its characteristics. They then describe their manner of applying the network concept, an approach whose originality consists in asking the patient to reunite his primary network (family, friends, neighbours, etc.) in order to identify the problems and to determine how (the network) can help. They develop a different approach from that of community psychiatry, by emphasizing the role of primary networks as emotional support structures and as a non-psychiatric solution. However, the network intervention is not presented as a cure-all and the authors conclude by describing the limitations of their approach.

English Abstract↗