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Biomedical subjects

I Eichhorn

Publications and source records attributed to I Eichhorn.

8 recordsLinked to original sources
PubMed1986

Differences in interferon-gamma response of psoriatic lymphocytes to stimulation with various mitogens.

Upon ConA stimulation, peripheral blood mononuclear leukocytes from psoriatic patients show an impaired IFN-gamma production. Normal IFN-gamma values were obtained, however, with PHA or PWM as inducers. Moreover, psoriatic cells responded well to vesicular stomatitis virus as inducer of IFN-alpha. Thus, the defect is not an all-out inability of all lymphocytes to produce IFN, but rather a failure to respond to weak mitogenic stimuli. Possible mechanisms are discussed.

Humans↗
PubMed1981

Ionic strength dependent structural changes of nucleosomes.

Rat thymus nucleosomes were studied as to their sedimentation behaviour and molecular weight Mr in NaCl and (NH)2SO4 solutions of different ionic strengths. The sedimentation coefficient s20,w decreases in two steps at ionic strengths of about 0.45-0.6 and of 1-1.2 and amounts to 11.0 S in salt-free buffer and to 5.5 S in 2 M NaCl-solution. This decrease in s20,w is paralleled by an analogous decrease in Mr. There is, however, an additional decline in Mr from 233 000 to 200 000 between the ionic strengths of 0.005 and 0.4. These changes are accompanied by conformational changes of nucleosomes as shown by varying molar frictional ratios f/f0. The decrease in Mr could be attributed to the successive release of histones as checked by electrophoretic analysis. Furthermore, nucleosomes in (NH4)SO4-solution proved to be more stable against increasing salt concentration than nucleosomes in NaCl-solution.

Ammonium Sulfate↗
PubMed1980

Isolation and characterization of salt-soluble, unsheared chromatin.

From rat liver nuclei depending on the extraction time, 10 to 20% of total chromatin has been extracted with a solution containing 0.1 M ammonium sulfate, 2 mM MnCl2, 0.1 M Tris-HCl, pH 7.9. We term this chromatin chromatin S. It has a protein: DNA ratio of 1.3, the full amount of the 5 histones in an undegraded state, and a RNA: DNA ratio of approximately 0.2. Its nonhistone protein pattern, obtained by gel electrophoresis exhibits a rich spectrum of proteins in a broad range of molecular weights. Electrophoretic analysis of the DNA fragments obtained by micrococcus nuclease digestion of chromatin S yields the same digestion pattern as that of nuclei. Thus, chromatin S fulfils an essential criterion of unsheared chromatin. In contrast to other chromatin preparations described so far, this chromatin is soluble at a salt concentration of 0.1 M ammonium sulfate. We have shown previously that it exhibits a compact conformation, low intrinsic viscosity and low radius of gyration obtained by light scattering measurements. Its mean molecular weight was determined to be nearly 10(8).

Animals↗
PubMed1977

Altered histone-DNA interactions in rat liver chromatin containing 5-bromodeoxyuridine-substituted DNA.

The extractability of the different histone types from rat liver chromatin was studied following the incorporation of bromodeoxyuridine (BrUdR) in liver DNA. This was accomplished by a continuous application of 20 mumol BrUdR/ml/h 17--41 after partial hepatectomy. As a result, thymidine (TdR) replacement by BrUdR of about 80% in the newly-synthesized DNA strand of approx. 30% of total liver DNA was obtained; this causes remarkable changes in the histone--DNA interactions as determined from the release of histones from liver nuclei by ammonium sulfate and ethidium bromide (EB), respectively. In particular, the relative amounts of the two slightly lysine-rich histones H2A and H2B remaining on the BrUdR chromatin proved to be about 3-fold higher than those remaining on the control chromatin of TdR-treated animals. Similarly, histones H1 and H3 tend to bind closer to BrUdR-containing DNA. These results may be of interst with regard to the well-known selective effects of BrUdR on differentiation processes.

Animals↗
PubMed1975

Evidence of altered histone interactions, as investigated by removal of histones, in chromatin isolated from rat liver nuclei by a conventional method.

It is shown that the release of the slightly lysine-rich histones f2a2 and f2b by 0.4 M ammonium sulfate from conventionally isolated chromatin is diminished in comparison to the lysed nuclei. The change in extractability is further demonstrated by the application of ethidium bromide. At a molar input ratio of 0.09 (moles ethidium bromide/moles nucleotide) and 0.4 M ammonium sulfate the slightly lysine-rich histones are released from the chromatin to 70 - 80% if the lysed nuclei are used. At 0.1 M ammonium sulfate ethidium bromide effected also a release of 50 % of histone f1. Comparable effects could not be observed with chromatin prepared in a conventional way but instead a tendency towards loss of histone f3 in the presence of ethidium bromide was observed.

Ammonium Sulfate↗
PubMed1975

[Effect of D20 on contractility and excitation contraction coupling in the rat papillary muscle].

D2O decreases the isometric contraction force of papillary muscles from the left ventricle of rats. This effect can be compensated only partially by increasing the calcium content in the perfusion solution. Differences in the effect of D2O under different calcium concentrations point also to an action site other than at the contractile proteins. The enlargement of the restitution of contraction 300 msec after the basic beat, the diminution of the postextrasystolic tiation and the disappearance of postextrasystolic depressions because of high calcium potencontent in the bathing solution make it more probable that the action site lies in cell compartments which may be involved into the supply of activator calcium. The increasing occurrence of aftercontractions alredy at slightly enhanced extracellular calcium is in good agreement with this fact.

Animals↗