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Biomedical subjects

F Wagner

Publications and source records attributed to F Wagner.

At least 91 records · Page 5Linked to original sources
PubMed1994

On the relation between phosphate uptake and growth of the cyanobacterium Anacystis nidulans.

The energy dependent phosphate uptake by the cyanobacterium Anacystis nidulans has been analysed in terms of a "linear energy converter" that describes the interrelationship between phosphate incorporation into the polyphosphate pool and the photosynthetic proton flux at the thylakoid membrane. It is assumed that both processes are coupled in such a way that uptake proceeds with optimal efficiency at the prevailing phosphate concentration in the growth medium. On the basis of this model two important parameters of the uptake system can be calculated: first, a conductivity coefficient that reflects the activity of the uptake system and second, a minimal threshold value of external phosphate at which uptake ceases. The theoretical data are shown to fit the experimentally observed uptake behaviour of cyanobacteria when the same population is subjected to a transition from growth on low to high phosphate concentrations, mimicking a situation that frequently leads in natural waters to an algal bloom.

Cyanobacteria↗
PubMed1994

Method dependency of blood group determination after bone marrow transplantation.

After minor-incompatible bone marrow transplantation (e.g. recipient A, donor 0), red cells are donor-type but absorb recipient-type AB0 substance from plasma. Because of discrepant results, we tested how such cells type with standard methods. In the tube test 7 of 8 patients showed donor type. In Diamed AB0 gel, weak-positive reactions were found with anti-AB in the patients (donor 0) tested. Commercial AB0 antibodies from different companies used in Diamed neutral gel trays differed widely in the results obtained. The strongest positive reactions were found with polyclonal anti-AB. The exact antibody and technique are crucial to the result of AB0 typing after minor-incompatible bone marrow transplantation.

ABO Blood-Group System↗
PubMed1994

[Application of indirect immunofluorescence in blood group serology].

Indirect fluorescence flow cytometry allows the quantification of erythrocytes with aberrant phenotype and the quantification of antigen density. These tasks may be performed using commercial blood group antisera. With adequate standardization, a variation coefficient < 5% for antigen density is achievable. Analysis of chimerism is of special interest after bone marrow transplantation.

Blood Grouping and Crossmatching↗
PubMed1994

[Occurrence of D category VI in blood donors in Baden-Württemberg].

33,830 repeated donors and 9,157 first donors were screened for DVI. All D-positive first donors and the repeated donors with depressed D antigen (Du) were tested with Seraclone anti-D (IgM) that is known to be nonreactive with DIV. D-positive donors who were negative with Seraclone anti-D were further evaluated with a monoclonal IgG anti-D nonreactive with DIV. By using a D-screen panel it was attempted to type donors who were also negative with these antibodies. With this procedure, among 42,987 donors, 4 donors with DVI and 2 donors with probable DVI or closely related variants were detected. This is in agreement with previous reports from Great Britain and Australia. These donors with qualitative variants represent 2% of donors previously typed as Du and 10% of D-positive donors who were negative with Seraclone.

Antibodies, Monoclonal↗
PubMed1993

[Osseous variations in the coronary CT of the paranasal sinuses].

Bony variations in the anterior ethmoids may, if severe, play an important role in the development of chronic sinusitis and present the surgeon with added risks during operation. We have, therefore, analysed 390 preoperative CT examinations of the sinuses performed in the coronary plane with respect to the frequency of bone variations. Concha bullosa, increased pneumatisation of the agger nasi, large ethmoidal bullae, Haller's cells and increased pneumatization of the sphenoid were found with equal frequency in about 20%. The most common variants occurred in the uncinate process (31.5%), less common were paradoxical curve of the middle turbinates (13.3%) and very rare were Onodi cells (1.3%).

Adolescent↗
PubMed1993

Adaptive phosphate uptake behaviour of the cyanobacterium Anacystis nidulans: analysis by a proportional flow-force relation.

The phosphate uptake system of the cyanobacterium Anacystis nidulans has the capacity to store information about former fluctuations in the environmental phosphate concentration. Using nonequilibrium thermodynamics to characterize this phenomenon we show that information storage leads to the development of an extended range of validity over which there is a proportional relationship between uptake rate and the driving force of this process. The limits of this range reflect the extent of earlier fluctuations in the environmental phosphate concentration.

Culture Media↗
PubMed1992

Affinity-purified c-Jun amino-terminal protein kinase requires serine/threonine phosphorylation for activity.

The addition of phorbol esters to U937 leukemic cells stimulates the phosphorylation of c-Jun on serines 63 and 73. To isolate the protein kinase which stimulates this phosphorylation, we have used heparin-Sepharose chromatography followed by affinity chromatography over glutathione-Sepharose beads bound with a fusion protein of glutathione S-transferase and amino acids 5-89 of c-Jun (GST-c-Jun). Using this procedure we purify a 67-kDa protein which is capable of phosphorylating GST-c-Jun as well as the complete c-Jun protein. By making mutations in serines 63 and 73 and then creating a fusion protein with GST (GST-c-Jun mut), we demonstrate that this protein kinase specifically phosphorylates these sites in the c-Jun amino terminus. Treatment of purified c-Jun amino-terminal protein kinase (cJAT-PK) with phosphatase 2A inhibits its ability to phosphorylate GST-c-Jun. This inactivated enzyme can be reactivated by phosphorylation with protein kinase C (PKC), although PKC is not capable of phosphorylating the GST-c-Jun substrate. Because v-Jun cannot be phosphorylated in vivo, we compared the ability of cJAT-PK to bind to GST-v-Jun or GST-c-Jun mut. The cJAT-PK bound 50-fold better to GST-c-Jun mut than GST-v-Jun suggesting that the delta domain which is missing in v-Jun plays a role in binding the cJAT-PK. These results suggest that there is a protein kinase cascade mediated by protein phosphatases and PKC which regulates c-Jun phosphorylation.

Cell Line↗
PubMed1992

Phorbol ester-induced amino-terminal phosphorylation of human JUN but not JUNB regulates transcriptional activation.

Phorbol ester tumor promoters activate gene transcription by regulating both the synthesis and posttranslational modification of the activator protein 1 (AP-1) transcription factor, c-Jun and JunB are components of the mammalian AP-1 complex. Here we demonstrate that in U-937 human leukemic cells, phorbol esters stimulate the phosphorylation of the amino terminus of human c-Jun (JUN) but not human JunB (JUNB). Mutational analysis indicates that serine-63 and -73, which reside within the putative regulatory domain of JUN, are required for both constitutive and phorbol 12-myristate 13-acetate-inducible N-terminal JUN phosphorylation. To determine the functional role of this N-terminal phosphorylation, we prepared several chimeric proteins containing the N-terminal 84 amino acids (positions 5-89) of human JUN or murine JUNB fused to the yeast GAL4 DNA-binding domain. This region was found to be sufficient for the phorbol ester-inducible transcriptional activity of JUN, but not JUNB. This induction was abolished by the mutation of serine-63 and -73 to leucine residues. Thus, we propose that phorbol esters enhance the trans-activation potential of JUN, but not JUNB, by the phosphorylation of the N-terminal regulatory domain of JUN.

Amino Acid Sequence↗
PubMed1992

Upstream regions of the c-jun promoter regulate phorbol ester-induced transcription in U937 leukemic cells.

To understand the mechanism by which phorbol esters (PMA) stimulate c-jun transcription in human leukemic cell line U937, we have mutated specific enhancer sequences within the c-jun promoter. We find in the region of DNA from -132 to +170 containing Sp1, C-TF and AP-1 sequences that mutation of the AP-1 sequence alone is not sufficient to abrogate transcription, and mutation of the Sp1 sequence increases transcription 4-fold. Although mutation of the CTF site had no effect, CTF and AP-1 mutations together totally abrogate PMA-induced transcription. In comparison mutations of either of these sites alone or together in a construct containing -1639/+740 of the c-jun promoter had no effect on transcription. Because this data suggested the possibility of other upstream control regions, we sequenced the promoter from -142 to -1639. This sequence demonstrates a greater than 70% homology between human, and mouse c-jun promoters for the region from -142 to -441, and a second AP-1-like site in the -183 to -192 region. Mutation of this site did not influence transcription by PMA. By making constructs containing varying portions of the promoter, we have identified the region between -142 and -711 to be responsible for mediating PMA-induced c-jun transcription.

Base Sequence↗
PubMed1992

Francis X. Dercum.

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History, 20th Century↗
PubMed1992

Ethanol inhibits interferon-gamma secretion by human peripheral lymphocytes.

Clinical and epidemiological evidence exists that subjects who chronically abuse alcohol are disposed to infections and certain types of cancer. In vitro inhibition of mitogen-induced lymphocyte proliferation has been shown suggesting a direct immunosuppressive effect of ethanol. Using human peripheral blood mononuclear cells we could demonstrate in vitro for the first time that even low ethanol concentrations of 6 and 12.5 mM significantly inhibit spontaneous and mitogen-induced secretion of interferon-gamma. This effect was more pronounced with lower mitogen stimulation and it increased in a dose dependent manner when higher ethanol concentrations were used. Inhibition of cell proliferation as measured by 3H-thymidine incorporation did not parallel the inhibition of interferon-gamma secretion. As this lymphokine exerts a great number of immunostimulating effects, diminished secretion might well contribute to the immune defect observed in alcoholics.

Alcohol Drinking↗