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Biomedical subjects

R Rudolph

Publications and source records attributed to R Rudolph.

At least 199 records · Page 11Linked to original sources
PubMed1981

The ultrastructure of chronic radiation damage in rat skin.

Chronic radiation skin ulcers were produced in rats with the administration of 5,000 or 8,000 rads. Electron microscopy revealed two phases of damage, the first from seven to 14 weeks and the second from 14 to 54 weeks. In the first phase, significant nuclear and cytoplasmic degeneration was prominent. During the second phase, lysosomes were common along with unusual cytoplasmic inclusions. Myofibroblasts were observed in the second phase only, suggesting that delayed would contraction in radiation ulcers was the result of the delayed onset of myofibroblast development.

Animals↗
PubMed1980

Histopathological Examinations of nasal polyps of different etiology.

A safe differentiation between allergic and non-allergic polyps appears impossible by means of light or electron microscopical examination of polyp tissue. There are some indications, however, which point to the allergic or non-allergic origin and it seems that the relationship between eosinophils and plasma cells with a low index is characteristic for polyps of allergic origin. Eosinophils and round-cell infiltrations are present in all types of polyps. An index of eosinophils to plasma cells below 5 is indicative for allergy and should induce the pathologist to give a hint to the clinican for allergological work-up. An index above 5 is more corresponding with infective etiology. Any changes of the basement membrane, i.e., smaller or larger gaps or even absence, are found only very irregularly and are not typical findings in either way. An increased number of glands and collagenic fibres, especially under the epithelium, are more an expression of the age of the polyp. Since the conservative therapy as mentioned above leads to good therapeutical results, it is desirable that an allergological work-up should be done in any case which shows the histological findings indicative for allergic etiology. Thus, repeated operations with all the risks and uncertain therapeutical benefit can be avoided.

Adolescent↗
PubMed1980

Kinetics of reconstitution of porcein muscle lactic dehydrogenase after reversible high pressure dissociation.

Porcine muscle lactic dehydrogenase can be reversibly dissociated into monomers at high hydrostatic pressure. The rate of dissociation depends on the conditions of the solvent (Schade et al., 1980, Biochemistry, in press). Maximum yields of reactivation are achieved after dissociation by 20 min incubation in 0.2 M Tris/HCl buffer or 0.2 M KCl at pH 7.6, in the presence of 10 mM dithioerythritol and 1 mM EDTA, provided that both dissociation and reassociation are performed under anaerobic conditions. At enzyme concentrations of the order of 1 microM reactivation amounts to greater than or equal to 95%, the product of reactivation being indistinguishable from the enzyme in its initial native state. Based on the long-term stability of the enzyme under the optimum given conditions of reactivation, the kinetics of reconstitution after pressure release were investigated over a wide range of enzyme concentrations (1 nM less than c less than 1 microM). The weakly sigmoidal kinetics may be described by an irreversible uni-bimolecular reaction scheme, corresponding to a sequential transconformation-association process. Assuming the protomers to be enzymatically inactive, the kinetic profiles may be fitted by one set of kinetic constants: kuni=1.5 X 10(-2) s-1 and kbi=7 X 10(3) s-1 M-1, the association step belonging to either dimer or tetramer formation.

Animals↗
PubMed1980

Rate enhancement of reconstitution of glyceraldehyde-3-phosphate dehydrogenase by a covalently bound coenzyme analog.

Kinetic analysis of the in vitro reconstitution of glyceraldehyde-3-phosphate dehydrogenase [D-glyceraldehyde-3-phosphate:NAD+ oxidoreductase (phosphorylating), EC 1.2.1.12] from yeast showed that both oxidized and reduced coenzyme enhance the transconformation reaction, which is rate limiting in the sequential folding-association process at high enzyme concentrations (Krebs, H., Rudolph, R. & Jaenicke, R. (1979) Eur. J. Biochem. 100, 359-364). In the present study the reconstitution of the enzyme has been analyzed after covalent modification with the coenzyme analog 3-[(3-bromoacetylpyridinio)-propyl]adenosine pyrophosphate. Reconstitution of the modified enzyme, as determined by the regain of the native tryptophan fluorescence, is found to be more then 10 times faster than refolding of the unmodified apoenzyme and more than 5 times faster than that of the unmodified holoenzyme. Various degrees of denaturation and the presence of up to 0.4 M guanidine . HCl do not affect the rate of reconstitution of the modified enzyme. The kinetic effect of free or covalently bound coenzyme is discussed in terms of a decrease in free energy of the native or native-like structure or in terms of a decreased activation energy of rate-limiting steps in the process of reconstitution. Stabilization of the dimeric intermediate or acceleration of its transformation seems to be the most likely explanation for the observed effect of free or covalently bound coenzyme on the rate of reconstitution.

Adenosine Diphosphate↗
PubMed1980

[alpha 1-antitrypsin determination in children with obstructive lung disease (author's transl)].

In 184 children and juvenile with type I respiratory allergies the AAT-content in serum was measured by the rocket technique. The results do show neither disease--nor agedependant changes. The mean of the total was 283 mg%. This value does agree very well with the normal values reported in literature. In 5 patients however (2,71%) of the total collective an intermediary AAT-deficiency was found. This frequency though lies within the percentage of occurrence in non-selected patients. The individual analysis of these cases did not give any valid connection to history, age, lung function, immunoglobulins and course of disease. On the basis of the demonstrated results it can be said, that the determination of AAT in serum patients with type-I-allergy is of no practical diagnostic value.

Adolescent↗
PubMed1980

Tissue effects of new silicone mammary-type implants in rabbits.

Two new types of silicone mammary-type implants designed to reduce silicone leakage by a gel barrier or to insulate tissue from silica in standard implants (by silicone coating) were placed in rabbits. Standard-type silicone implants were placed as controls. Capsules histologically similar to those that occur in humans occurred around many implants, although no grossly visible capsular contraction occurred. Inflammation was minimal around all types of implants, and the capsules appeared similar. Myofibroblasts were seen around implants within the first three weeks only. Scanning electron microscopy with energy-dispersive x-ray analysis was used to positively identify silicon in tissues around the implants. Silicon was found in tissues from 55% of the standard and 60% of the silicone-coated implants, while it was found in only 10% of capsules around implants containing a gel barrier layer. We conclude that both kinds of new implants incite minimal reaction in rabbits, and that a gel barrier can reduce silicone leakage from silicone implants.

Animals↗
PubMed1980

Ultrastructure of active versus passive contracture of wounds.

Myofibroblast populations in skin scar contracture due to wound contraction and in joint contracture due to passive position were compared in male New Zealand rabbits. Active contraction was produced by removal of full thickness back skin, with healing by contraction and epithelization. Joint contracture was produced by forced knee flexion for nine weeks by means of Steinman pin fixation. Electron microscopy revealed complete absence of myofibroblasts in the contracture due to position in contrast to prominent myofibroblasts in contracted skin scars. Contracture due to position is, thus, due to collagen remodeling alone, without an active contraction process. This suggests that the potential use of drugs for biochemical control of contracture will have to take into account how the contracture formed.

Animals↗
PubMed1979

Reconstitution of lactic dehydrogenase. Noncovalent aggregation vs. reactivation. 2. Reactivation of irreversibly denatured aggregates.

Noncovalent aggregation is a side reaction in the process of reconstitution of oligomeric enzymes (e.g., lactic dehydrogenase) after preceding dissociation, denaturation, and deactivation. The aggregation product is of high molecular weight and composed of monomers which are trapped in a minium of conformational energy different from the one characterizing the native enzyme. This energy minimum is protected by a high activation energy of dissociation such that the aggregates are perfectly stable under nondenaturing conditions, and their degradation is provided only by applying strong denaturants, e.g., 6 M guanidine hydrochloride at neutral or acidic pH. The product of the slow redissolution process is the monomeric enzyme in its random configuration, which may be reactivated by diluting the denaturant under optimum conditions of reconstitution. The yield and the kinetics of reactivation of lactic dehydrogenase from pig skeletal muscle are not affected by the preceding aggregation-degradation cycle and are independent of different modes of aggregate formation (e.g., by renaturation at high enzyme concentration or heat aggregation). The kinetics of reactivation may be described by one single rate-determining bimolecular step with k2 = 3.9 x 10(4) M-1 s-1 at zero guanidine concentration. The reactivated enzyme consists of the native tetramer, characterized by enzymatic and physical properties identical with those observed for the enzyme in its initial native state.

Animals↗