Search PubMed⌕ Search

Biomedical subjects

R Zimmermann

Publications and source records attributed to R Zimmermann.

At least 541 records · Page 30Linked to original sources
PubMed1977

Kinetic studies on the transport of cytoplasmically synthesized proteins into the mitochondria in intact cells of Neurospora crassa.

The transport of cytoplasmically synthesized mitochondrial proteins was investigated in whole cells of Neurospora crassa, using dual labelling and immunological techniques. In pulse and pulse-chase labelling experiments the mitochondrial proteins accumulate label. The appearance of label in mitochondrial protein shows a lag relative to total cellular protein, ribosomal, microsomal and cytosolic proteins. The delayed appearance of label was also found in immunoprecipitated mitochondrial matrix proteins, mitochondrial ribosomal proteins, mitochondrial carboxyatractyloside-binding protein and cytochrome c. Individual mitochondrial proteins exhibit different labelling kinetics. Cycloheximide inhibition of translation does not prevent import of proteins into the mitochondria. Mitochondrial matrix proteins labelled in pulse and pulse-chase experiments can first be detected in the cytosol fraction and subsequently in the mitochondria. The cytosol matrix proteins and those in the mitochondria show a precursor-product type relationship. The results suggest that newly synthesized mitochondrial proteins exist in an extra-mitochondrial pool from which they are imported into the mitochondria.

Biological Transport↗
PubMed1976

Mössbauer and EPR spectroscopy of protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa.

Protocatechuate 3,4-dioxygenase (EC 1.13.11.3) from Pseudomonas aeruginosa has been investigated by EPR and Mössbauer spectroscopy. Low temperature Mössbauer data on the native enzyme (Fe3+, S = 5/2) yields a hyperfine field Hsat=-525 kG at the nucleus. This observation is inconsistent with earlier suggestions, based on EPR data of a rubredoxin-like ligand environment around the iron, i.e. a tetrahedral sulfur coordination. Likewise, the dithionite-reduced enzyme has Mössbauer parameters unlike those of reduced rubredoxin. We conclude that the iron atoms are in a previously unrecognized environment. The ternary complex of the enzyme with 3,4-dihydroxyphenylpropionate and O2 yields EPR signals at g = 6.7 and g = 5.3; these signals result from an excited state Kramers doublet. The kinetics of the disappearance of these signals parallels product formation and the decay of the ternary complex as observed in the optical spectrum. The Mössbauer and EPR data on the ternary complex establish the iron atoms to be a high-spin ferric state characterized by a large and negative zero-field splitting, D = approximately -2 cm-1.

Binding Sites↗
PubMed1976

[Extirpation of nasopharyngeal fibromas after selective preoperative angiographic embolization].

The gross amount of bleeding during surgical removal of nasopharyngeal angiofibromas is feared. An excellent method to reduce this amount is the preoperative selective embolization of the feeding vessels of these tumors under angiographic control. The advances in selective angiography of the branches of the external carotid artery by femoral catheterization make it possible to applicate Gelfoam emboli in the very arteries which are to be embolized. There is a case report about two young men who have been pretreated in this manner. The intraoperative bleeding was minimal.

Embolization, Therapeutic↗
PubMed1975

[The effect of acetylsalicylic acid, extremely restricted movement and a cholesterol-rich diet on atheromatosis of the rabbit aorta: comparative investigations (author's transl)].

A multifactorial model for demonstrating the pathogenesis of the diet-induced atheromatosis of the rabbit is described. We examined the effect of various diets (atherogenetic, rich in fibre, mixed, normal) and of extreme restriction of movement, with and without doses of acetylsalicylic acid. The aorta showed uniforms morphological findings; 1. Acetylsalicilic acid no influence on the cholesterol-induced atheromatosis of the rabbit; 2. An atherogenic diet and a diet rich in raw fibre caused different degrees of sclerosis of the aorta; this was related to the cholesterol content of the mixed diet, which was 50% less than the cholesterol content of the atherogenic diet; 3. Macro- and microscopic examination showed that extreme restriction of movement alone has no demonstrable effect on the aorta of the rabbit; 4. The cholesterol-induced atheromatosis showed significantly less involvement of the aorta when there was extreme restriction of movement in addition to the diet; 5. In none of the test groups could we demonstrate any effect of PAT I on platelet adhesiveness; 6. The test conditions did not result in an activation of the contact phase of the haemocoagulation system.

Animals↗