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Biomedical subjects

E Hofmann

Publications and source records attributed to E Hofmann.

At least 217 records · Page 12Linked to original sources
PubMed1980

Familial glomerulopathy with giant fibrillar deposits.

Proteinuria and microhaematuria were observed in three siblings and one first-degree cousin. Histological examination of three kidney biopsies and one autopsy specimen shows the same diffuse glomerular lesions in all patients, characterized by mainly subendothelial but frequently transmembranous and mesangial deposits of a unique fibrillar structure, visible by electron microscopy. Examination by immunfluorescence gave inconstant findings. No serological abnormalities could be established. To our knowledge, such a pecular form of familial glomerulopathy has not been described so far.

Adult↗
PubMed1980

[Chronic hypophosphatemic osteopathy (author's transl)].

The process of chronic hypophosphatemic vitamin D-resistant rickets--observation of two cases. With the male patient--our first case--the disease was sporadic and had not been recognized for a long time. In his early adulthood it manifested itself as Umbauzonen (pseudofractures) in the larger context of active osteomalacia. It was possible to observe the pseudofractures before and while the patient was treated with drugs. High doses of vitamin D 3 and dosage of phosphate mitigated the complains although with respect to the radiological, scintigraphic, humoral and histological findings there was only slow improvement or no improvement at all.--The patient's daughter is affected by the disease as well. In her case the pathological signs of her bones became better when treated with vitamin D 3.

Adult↗
PubMed1979

[Cellular immunity: in vitro leukocyte migration inhibition does not correlate with the tuberculin skin test].

The leukocyte migration inhibition test (LMIT) is said to be an in-vitro correlate of cell mediated immunity in vivo. The authors' series of experiments, however, in which they compared skin tests and LMIT (taking the same tuberculin for both tests), showed wed no correlation between the two tests. The discrepancy between these results and those of other authors may be due to the fact that the authors worked under sterile conditions. It is known that contamination even by minute amounts of endotoxin may alter the results of in-vitro tests of cell mediated immunity. The authors therefore question the value of the LMIT as an in-vitro counterpart of the skin test.

Blood Sedimentation↗
PubMed1979

[Control mechanisms of aphasic patients in verbal and phonemic paraphasias (author's transl)].

In the current literature on aphasia, two explanations of paraphasic errors are suggested: one is based on the idea of conscious verbal substitutions, and the other on that of uncontrolled faults in production. The purpose of this study was to relate both explanations to a) the usual classification of verbal and phonemic paraphasias, b) the different types of aphasia, and c) the severity of the aphasic disturbance. In free reproductions of 19 fluent aphasics A(F) and 21 nonfluent aphasics A(NF), the immediate verbal context of paraphasias was examined in relation to a) the nature and severity of the paraphasic errors and b) the severity of the aphasia. The A(NF) group made significantly more hesitations before both verbal and phenemic paraphasias. There was no significant difference between the two groups in control after phonemic paraphasias, but the A(NF) showed a significantly higher rate of control incidents after verbal paraphasias. Thus the two explanations of paraphasia may correspond to different kinds of paraphasic behavior, which are symptomatic of two varieties of aphasia, fluent and nonfluent.

Adult↗
PubMed1979

Kinetic modelling of yeast phosphofructokinase.

Phosphofructokinase from baker's yeast (Saccharomyces cerevisiae) is an octameric enzyme which exhibits complex allosteric behaviour. In contrast to mammalian phosphofructokinase, the enzyme does not show association-dissociation behaviour. A systematic kinetic investigation at pH 7.2 in dependence on the substrates, fructose 6-phosphate and ATP as well as on the effectors AMP and ADP is presented. The results are interpreted in terms of a structure oriented theoretical model. Because the two state model of Monod, Wyman and Changeux proved to be insufficient for interpretation of the experimental data, it was extended to a four state model in which the basic conformations R and T of the enzyme are split into subconformations R1 and R2 as well as T1 and T2, respectively. It is assumed that fructose 6-phosphate and the adenine nucleotides influence different allosteric equilibria. The model permits a precise quantitative description of the experimental data.

Adenosine Diphosphate↗
PubMed1979

Non-linear dynamic phenomena in open reconstituted enzyme systems.

The dynamic pattern of an open reconstituted in-vitro enzyme system containing phosphofructokinase, pyruvate kinase and adenylate kinase has been investigated. The approach is experimentally based on a stirred flow-through reactor. Stationary concentrations of phosphofructokinase and pyruvate kinase are maintained by entrapment in polyacrylamide gel particles. The results fit to a theoretical model based on the initial kinetic responses of the enzymes involved. An S-shaped steady state input characteristic for fructose 6-phosphate has been experimentally obtained.

Adenosine Triphosphate↗
PubMed1978

Kinetic investigation of the interaction of cibacron blue F3G-A with phosphofructokinase from yeast.

Yeast phosphofructokinase is strongly inhibited by Cibacron Blue F3G-A. The inhibition is competitive in respect to the phosphate donor. Fructose 6-phosphate and ATP are able to abolish the dye-inhibition. Replacement of the strong inhibitor ATP by ITP as phosphate donor gives qualitatively analogous effects. The influence of Cibacron Blue F3G-A on the kinetic pattern of yeast phosphofructokinase can be described in terms of the kinetic model of Freyer et al. [8] if one assumes that the dye binds to the ATP-binding sites in a competitive manner.

Anthracenes↗
PubMed1978

Relationships between association state and enzymic activity of human erythrocyte phosphofructokinase.

Human erythrocyte phosphofructokinase has been subjected to active band centrifugation and stability measurements over a broad range of conditions. The enzyme behaves differently in-Tris buffer containing ATP and phosphate buffer containing fructose 6-phosphate. In the first buffer, dissociation is favoured and after prolonged storage of the enzyme tetramers represent the highest state of association. At 4 degrees C the enzyme exhibits the phenomenon of reversible cold-inactivation. This property is attributed to slow dissociation of the active associated states of the enzyme to dimers. The cold-inactivated enzyme can be reactivated by fructose 1,6-bisphosphate. Inorganic phosphate and fructose 6-phosphate have been found to protect the enzyme from cold-inactivation. Under these conditions, the sedimentation coefficient and the specific activity depend on the enzyme concentration only. The specific activity does not change on storage of the diluted enzyme at 4 degrees C. At 20 degrees C, however, a slow activation proceeds during incubation of the diluted enzyme. The correlations between the association state and the enzymic activity are discussed.

Enzyme Activation↗
PubMed1978

Association behaviour of human erythrocyte phosphofructokinase. Dependence of molecular weight on enzyme concentration as analyzed by frontal gel chromatography.

Self-association of human erythrocyte phosphofructokinase has been studied at pH 8.0 and at 4 degrees C in the presence of 2 mM fructose 6-phosphate by means of frontal gel chromatography. Under these conditions the basic associating catalytically active species is the tetramer of the enzyme with a molecular weight of about 330000, the monomers of which having a molecular weight of 83000 as determined by sodium dodecyl sulphate electrophoresis. The experimental data have been compared with various models describing the enzyme association. The mode of association can sufficiently be described by assuming a weakly negative cooperative process in which the association constant of the nucleation step (association of two tetramers to an octamer) is larger than that of the following propagation steps. The geometry of association appears to be approximately spherical.

Chromatography, Gel↗
PubMed1978

Modification of yeast phosphofructokinase by trypsin and subtilisin in the presence of effectors.

Yeast phosphofructokinase was subjected to limited proteolysis by trypsin in the presence of different effectors. It could be demonstrated that the substrates MgATP and fructose-6-phosphate are able to protect the enzyme from inactivation by trypsin. Other effectors like AMP, ADP, phosphoenolpyruvate, citrate and ammonium ions exhibit only negligible effects. During the first step of degradation consisting in the conversion of the subunits from Mr 120,000 to 90,000 no significant effects of the substrates and effectors on the proteolytic inactivation of yeast phosphofructokinase can be observed. In the presence of ATP as well as of ADP the sensitivity of the enzyme against ATP inhibition is either not or only slightly influenced by proteolytic modification. The modified enzyme retains its sensitivity against activation by AMP, independently of whether effectors are present or absent during proteolysis. The kinetic parameters of the enzyme modified by subtilisin in the presence of ATP or of fructose-6-phosphate have been determined.

Adenosine Diphosphate↗