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Biomedical subjects

B Friedrich

Publications and source records attributed to B Friedrich.

At least 127 records · Page 7Linked to original sources
PubMed1985

Mycoplasma mimicry of lymphokine activity in T-cell lines.

During screening of T-T hybridomas for B-cell-stimulating factors (BSF) we found in the conditioned medium of such a line (TUH-14) an activity that turned out to cosediment with a contaminating strain of Mycoplasma arginini on centrifugation. Since it only affected B blasts and only to a minor extent small cells and since it did not induce immunoglobulin secretion, the mycoplasma strain seemed to mimic a BSF. M. arginini was also found in two other T-T hybridoma producer lines but not in a clone of the EL-4 line. Three other M. arginini isolates were not stimulatory for B cells. The presented results point towards the importance of careful control for mycoplasma contamination in established cell lines.

Animals↗
PubMed1985

Denitrification by Alcaligenes eutrophus is plasmid dependent.

Curing of the hydrogenase-specifying megaplasmid pHG indigenous to strains of the facultative lithoautotrophic bacterium Alcaligenes eutrophus was correlated with a loss of denitrifying ability (Nitd). The retransfer of plasmid pHG1 reconstituted the Nitd phenotype. Plasmid-free mutants were still capable of converting some nitrate to nitrite, but they did not metabolize nitrite under anaerobic conditions.

Alcaligenes↗
PubMed1984

[Diagnostic and therapeutic aspects in the treatment of bee venom allergy].

In 50 patients who had severe allergic general reactions after a bee sting clinical and immunological parameters were examined under the desensitisation with apitoxin. Under the introduction of the hospital treatment 25 patients showed side effects. 14 of these patients had milder general reactions also during the further continuation of the ambulatory treatment. In no case the treatment had to be stopped. The behaviour of the specific IgE and IgG antibodies does not allow a prognostic evidence concerning possible side effects and is little suited for the individual case also as objective parameter of success. 17 patients who during the first weeks after the beginning of the therapy spontaneously had been stung by a bee did not show any reactions or only reduced reactions. This result shows that the desensitization of desensitized patients gives a secure protection from life-threatening incidents. Open remains among others the problem of the objective judgment of the therapy and thus the question of the duration of the treatment.

Adolescent↗
PubMed1984

Isolation and characterization of megaplasmid DNA from lithoautotrophic bacteria.

A method is described for the preparative isolation of megaplasmids ranging in size from 340 to 700 kb. These plasmids were isolated from chemolithoautotrophic bacteria including the species Alcaligenes, Pseudomonas, and Paracoccus. The procedure was based on alkaline sodium dodecyl sulfate lysis of the cells, followed by heat treatment, salt precipitation, several phenol extractions, dialysis steps, and proteinase and RNase treatment. The various parameters were evaluated and controlled. Hydrogen-oxidizing-ability (Hox) encoding plasmids were compared by EcoRI restriction enzyme analysis. pHG plasmids from Alcaligenes eutrophus wild-type strains appeared to be closely related; plasmids derived from the type strain TF93 and from A. hydrogenophilus exhibited major differences in restriction sites. Two cryptic plasmids harbored by Pseudomonas facilis and Paracoccus denitrificans showed scarcely detectable similarity to the plasmid species of Alcaligenes.

Alcaligenes↗
PubMed1984

Expression of hydrogenase in Alcaligenes spp. is altered by interspecific plasmid exchange.

Alcaligenes hydrogenophilus was found to contain a soluble and a particulate hydrogenase whose control and structure differed in part from that in Alcaligenes eutrophus. One of at least two plasmids indigenous to A. hydrogenophilus determines hydrogenase genes (Hox). The interspecific exchange of Hox-encoding plasmids generated transconjugants which expressed the structural and regulatory Hox phenotype of the donor.

Alcaligenes↗
PubMed1984

Alcaligenes eutrophus hydrogenase genes (Hox).

Mutants of Alcaligenes eutrophus H16 lacking catalytically active soluble hydrogenase (Hos-) grew very slowly lithoautotrophically with hydrogen. Mutants devoid of particulate hydrogenase activity (Hop-) were not affected in growth with hydrogen. The use of Hos- and Hop- mutants as donors of hydrogen-oxidizing ability in crosses with plasmid-free recipients impaired in both hydrogenases (Hox-) resulted in transconjugants which had inherited the plasmid and the phenotype of the donor. This indicates that the structural genes which code for the hydrogenases reside on plasmid pHG1. The Hox function of one class of Hox- mutants could not be restored by conjugation. These mutants exhibited a pleiotropic phenotype since they were unable to grow with hydrogen and also failed to grow heterotrophically with nitrate (Hox- Nit-). Nitrate was scarcely utilized as electron acceptor or as nitrogen source. Hox- Nit- mutants did not act as recipients but could act as donors of the Hox character. Transconjugants derived from those crosses were Hox+ Nit+, indicating that the mutation which leads to the Hox- Nit- phenotype maps on the chromosome. Apparently, the product of a chromosomal gene is involved in the expression of plasmid-encoded Hox genes. We observed that the elimination of plasmid pHG1 coincided with the occurrence of multiple resistances to various antibiotics. Since Hox+ transconjugate retained the antibiotic-resistant phenotype, we conclude that this property is not directly plasmid associated.

Alcaligenes↗
PubMed1984

[Roentgenologic aspects of bone healing in pathological fractures].

Under operative or non-operative treatment bone healing of pathological fractures acts the same way as in case of traumatic fractures which is shown by several examples. Depending on the degree of the fracture stability the response of bone is either primary or secondary healing reaction.

Bone Neoplasms↗
PubMed1984

Lymphokine-like activity of a strain of Mycoplasma arginini.

A Mycoplasma arginini strain, found to contaminate a T-T hybridoma designated TUH-14, was the source of a lymphokine-like activity with an ability to stimulate B-blasts to proliferate. Maturation to immunoglobulin secretion induced by the mycoplasma alone was low compared with induction by lipopolysaccharide (LPS), but could reach the same levels achieved with LPS by the addition of a B-cell maturation factor obtained from lectin-activated EL-4 thymoma cells. The mitogenic effect on B-cells was found only in the strain isolated from TUS-14; three other M. arginini strains were negative. Both mitogenic and nonmitogenic mycoplasma membrane preparations displayed higher affinity for B-cells than for T-blasts. However, membranes from the mitogenic strain, the TUH-14 isolate, bound better to activated blasts than to small resting cells, in contrast to the nonmitogenic strain G-230.

Adhesiveness↗
PubMed1983

Transfer and expression of the herbicide-degrading plasmid pJP4 in aerobic autotrophic bacteria.

Plasmid pJP4 encoding the ability to degrade the herbicide 2,4-dichlorophenoxyacetic acid (Tfd+) was transferred by conjugation from Escherichia coli JMP397 to various lithoautotrophic strains of Alcaligenes eutrophus and to the autotrophic bacterium Pseudomonas oxalaticus. The herbicide-degrading function of the plasmid was phenotypically expressed in all of the recipients. The majority of Tfd+ transconjugants also exhibited additional plasmid-encoded properties such as 3-chlorobenzoate degradation, resistance to mercuric ions, and sensitivity to the male-specific bacteriophage PR11. Furthermore, Tfd+ transconjugants were able to act as donors of plasmid pJP4. Physical evidence is presented by agarose gel electrophoresis showing that plasmid pJP4 coexisted with the resident plasmids widely distributed in this group of bacteria. However, in some of the hosts plasmids pJP4 was not stably maintained, had a reduced size and tended to form multimers.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1983

Regulation of hydrogenase formation is temperature sensitive and plasmid coded in Alcaligenes eutrophus.

Alcaligenes eutrophus grew well autotrophically with molecular hydrogen at 30 degrees C, but failed to grow at 37 degrees C (Hox Ts). At this temperature the strain grew well heterotrophically with a variety of organic compounds and with formate as an autotrophic substrate, restricting the thermolabile character to hydrogen metabolism. The soluble hydrogenase activity was stable at 37 degrees C. The catalytic properties of the wild-type enzyme were identical to those of a mutant able to grow lithoautotrophically at 37 degrees C (Hox Tr). Soluble hydrogenase was not rapidly degraded at elevated temperatures since the preformed enzyme remained stable for at least 5 h in resting cells or was diluted by growth, as shown in temperature shift experiments. Immunochemical studies revealed that the formation of the hydrogenase proteins was temperature sensitive. No cross-reactivity was detected above temperatures of 34 degrees C. The genetic information of Hox resides on a self-transmissible plasmid in A. eutrophus. Using Hox Tr mutants as donors of hydrogen-oxidizing ability resulted in Hox+ transconjugants which not only had recovered plasmid pHG1 and both hydrogenase activities but also were temperature resistant. This is evidence that the Hox Tr phenotype is coded by plasmid pHG1.

Alcaligenes↗
PubMed1982

Mutagenesis of Alcaligenes eutrophus by insertion of the drug-resistance transposon Tn5.

Drug-resistance element Tn5 coding for kanamycin resistance was used for mutagenesis of Alcaligenes eutrophus strain H16. The vehicle for introducing Tn5 into A. eutrophus was plasmid pJB4JI harboured by Escherichia coli. Kanamycin-resistant transconjugants occurred at a frequency of approximately 5 x 10(-8). One third of the transconjugants exhibited other plasmid-coded resistances such as gentamycin and spectinomycin. However, the latter markers were not stably maintained in the new host. Among the kanamycin-resistant transconjugants three classes of mutants were found: (i) Auxotrophic mutants occurred at a frequency of 0.8% and showed requirements for histidine, methionine, aspartate or isoleucine. Out of eleven auxotrophic mutants examined eight reverted to prototrophy. However, none of the revertants was kanamycin-sensitive. (ii) Mutants unable to grow with fructose as the carbon source occurred at a frequency of almost 10%. (iii) Mutants which had lost the ability to grow autotrophically with hydrogen and carbon dioxide were found at a frequency of 1%. Further analyses revealed that this class of mutants was either defective in carbon dioxide fixation or impaired in hydrogen metabolism.

Alcaligenes↗
PubMed1982

Nickel in the catalytically active hydrogenase of Alcaligenes eutrophus.

Nickel is a constituent of soluble and particulate hydrogenase of Alcaligenes eutrophus. Incorporation of 63Ni2+ revealed that almost the total nickel taken up by the cells was bound to the protein. Chromatography of a crude extract on diethylaminoethyl cellulose demonstrated an association of 63Ni2+ with soluble and particulate hydrogenase, supported by further analysis like polyacrylamide gel electrophoresis. Unspecific binding of 63Ni2+ to the protein was excluded by comparison with a mutant extract free of hydrogenase protein. X-ray fluorescence analysis of the homogeneous soluble hydrogenase indicated the presence of 2 mol of nickel per mol of enzyme, whereas the amount of nickel determined by incorporation of 63Ni2+ was calculated to be approximately 1 mol/mol of enzyme. Cells grown under nickel limitation contained catalytically inactive, but serologically active, soluble and particulate hydrogenase. The immunochemical reactions were only partially identical with the enzyme from nickel-cultivated cells indicating a structural modification of the proteins in the absence of nickel. It is concluded that nickel is essential for the catalytic activity of hydrogenase and not involved as a regulatory component in the synthesis of this enzyme.

Alcaligenes↗
PubMed1981

In vivo inactivation of soluble hydrogenase of Alcaligenes eutrophus.

The soluble, NAD+-reducing hydrogenase in intact cells of Alcaligenes eutrophus was inactivated by oxygen when electron donors such as hydrogen or pyruvate were available. The sole presence of either oxygen or oxidizable substrates did not lead to inactivation of the enzyme. Inactivation occurred similarly under autotrophic growth conditions with hydrogen, oxygen and carbon dioxide. The inactivation followed first order reaction kinetics, and the half-life of the enzyme in cells exposed to a gas atmosphere of hydrogen and oxygen (8:2, v/v) at 30 degrees C was 1.5h. The process of inactivation did not require ATP-synthesis. There was no experimental evidence that the inactivation is a reversible process catalyzed by a regulatory protein. The possibility is discussed that the inactivation is due to superoxide radical anions (O2-) produced by the hydrogenase itself.

Adenosine Triphosphate↗
PubMed1981

Nickel requirement for active hydrogenase formation in Alcaligenes eutrophus.

The nickel-dependent chemolithoautotrophic growth of Alcaligenes eutrophus is apparently due to a requirement of nickel for active hydrogenase formation. Cells grown heterotrophically with fructose and glycerol revealed a specific activity of soluble and membrane-bound hydrogenase which was severalfold higher than the normal autotrophic level. The omission of nickel from the medium did not affect heterotrophic growth, but the soluble hydrogenase activity was reduced significantly. In the presence of ethylenediaminetetraacetic acid (EDTA), almost no hydrogenase activity was detected. The addition of nickel allowed active hydrogenase formation even when EDTA was present. When chloramphenicol was added simultaneously with nickel to an EDTA-containing medium, almost no hydrogenase activity was found. This indicates that nickel ions are involved in a process which requires protein synthesis and not the direct reactivation of a preformed inactive protein. The formation of the membrane-bound hydrogenase also appeared to be nickel dependent. Autotrophic CO2 assimilation did not specifically require nickel ions, since formate was utilized in the presence of EDTA and the activity of ribulosebisphosphate carboxylase was not affected under these conditions.

Alcaligenes↗