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U Müller

Publications and source records attributed to U Müller.

At least 595 records · Page 33Linked to original sources
PubMed1978

Supranucleosomal structure of chromatin.

Rat liver chromatin was moderately digested by micrococcal nuclease and analysed by centrifugation in isokinetic sucrose gradients and electron microscopy. Two classes of particles sedimenting with about 33S and 60S were characterized. Kinetics of their appearance and disappearance during progressive digestion suggests that they represent monomers and dimers cleaved from a higher order (supranucleosomal) structure of chromatin. Biochemical and electron microscopical results suggest that the monomers and dimers contain eight and sixteen nucleosomes, respectively, which are densely packed into 23 nm (monomer) and 29 nm (dimer) globules.

Animals↗
PubMed1978

Biochemical and ultrastructural analysis of SV40 chromatin.

SV40 chromatin can be isolated in two forms: At moderate ionic strength (mu = 0.1-0.3) it contains histone H1 in addition to the four nucleosomal histones and has a highly condensed appearance in the electron microscope, being composed of a few closely connected large spheres [190 A (160, 220) diameter]. At high ionic strength (mu = 0.6-0.8) or after prolonged exposure to very low ionic strengths (mu less than 0.02), the compact form unfolds and the chromatin shows a typical nucleosomal morphology. Native SV40 DNA-protein complexes contain a median number of 24 nucleosomes. The number of superhelical turns does not differ in DNA obtained from the compact and the unfolded forms of chromatin. DNA-relaxing enzyme is found associated with SV40 chromatin and is capable of acting both on extraneously added circular DNA and on its own DNA in the nucleoprotein complex. Purified DNA-relaxing enzyme forms transiently nicked DNA intermediates where the enzyme can be found covalently attached to the site of the nick in the DNA. Transcriptionally active SV40 complexes undergo the same ionic-strength-dependent structural transition as that of bulk SV40 chromatin and may therefore also have a compact configuration at physiological salt concentrations.

Cell Line↗
PubMed1978

Hymenoptera sting hypersensitivy: IgE, IgG and haemagglutinating antibodies to bee venom constituents in relation to exposure and clinical reaction to bee stings.

High levels of IgE antibodies (Ab) to bee venom constituents were mainly found in patients with bee sting hypersensitivity, whereas the sera of bee keepers usually contained high levels of IgG Ab and haemagglutinins, representing blocking antibody activity. In bee keepers there was a positive correlation between the degree of severity of an adverse reaction to bee stings and IgE Ab, a negative one between the severity of reaction and IgG Ab and haemagglutinins, a positive one between the number of stings per season and IgG Ab and haemagglutinins, and negative one between the number of stings and IgE Ab. This suggests a mutual dependence of the production of IgE Ab and blocking Ab in a regularly exposed population. No such correlation was found in bee sting-allergic patients, indicating that other factors influence the severity of reaction in this only sporadically exposed group. The values of IgG Ab and haemagglutinins correlated well with each other, with IgG Ab giving a better correlation with severity of reaction and number of stings than the haemagglutinins.

Anaphylaxis↗
PubMed1978

Use of RAST technique in wasp sting hypersensitivity. Cross-reactions between various insect antigens are specially considered.

Clinical hypersensitivity to wasp stings was found to be fairly well correlated with the presence of serum IgE-antibodies against yellow jacket venom as detected by the RAST technique. Such antibodies were never found in a control group of non-allergic blood donors, but they were detected in a surprisingly large proportion of patients with bee sting allergy without known allergic reactions to wasps. Studies using RAST inhibition technique failed to prove cross-reactions between bee and wasp venoms. Considerably better results were obtained when venom antigens instead of whole body antigens were used in the RAST. RAST inhibition studies suggested that IgE-antibodies detected with RAST using whole body antigen are directed against bee venom constituents in the whole body extract.

Antibodies↗
PubMed1978

Formate dehydrogenase from Pseudomonas oxalaticus.

Formate dehydrogenase (EC 1.2.1.2) from Pseudomonas oxalaticus has been isolated and characterized. The enzyme (molecular weight 315000) is a complex flavoprotein containing 2 FMN, 18--25 non-heme iron atoms and 15--20 acid-labile sulphides. In the last step of the purification, a sucrose gradient centrifugation, a second catalytically active species has been found apparently originating from a dissociation of the enzyme into two equal subunits. The enzyme is specific toward its natural substrate formate. It transfers electrons to NAD+, oxygen, ferricyanide, and a lot of nonphysiological acceptors (dyes). In addition electrons are transferred from NADH to these acceptors. The (reversible) removal of FMN requires a reduction step. Reincorporation has been followed by the reappearance of the reactivity against formate and by fluorescence titration. The deflavo enzyme also binds FAD and riboflavin. The resulting enzyme species show characteristic catalytic abilities. Activity against formate is peculiar to the FMN species.

Aldehyde Oxidoreductases↗
PubMed1977

[Biochemical studies on hypotrophy and hypoplasia in the post partum uterus of the rat (author's transl)].

In post partum rat uteri, the wet weight, the soluble protein and the DNA content were measured for ten days following delivery. After a lag period of 48 h, the weight and protein content of whole uteri decreased in parallel to one twelfth of the initial values. The DNA content did not change significantly. Hypoplasia contributed not more than 20% to the weight loss, so that at least 80% of the loss was due to hypotrophy. The protein content per cell nucleus (mg protein/mg DNA) decreased by 85% within 10 days. In non-pregnant control animals, uterus weight and protein content per cell nucleus were greater than those of animals measured on the tenth post partum day. In contrast, the protein concentration of the tissue (mg protein/g wet weight) was lower in the control group. It is suggested that this hyperinvolution is caused by the low estrogen levels of the lactating animals.

Animals↗