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Biomedical subjects

R Franke

Publications and source records attributed to R Franke.

At least 19 recordsLinked to original sources
PubMed1991

[Behavior therapy oriented group therapy for anxiety disorders in neurorehabilitation].

The following are the experiences we have made with a group therapeutical care of patients suffering from anxiety disorders during neurorehabilitation. After individual analysis of content and background of anxiety disorders the patient receives a coping in group therapy process focussing on the main issue of anxiety on psychic consequences, knowing the background of the manner of anxiety and origin and elaborating long time strategies to cope anxiety. Our two years experiences show, that especially group therapy leads to facilities and economy of the therapeutical process.

Adaptation, Psychological↗
PubMed1987

Deoxylysolecithin and a new biphenyl detergent as solubilizing agents for bovine rhodopsin. Functional test by formation of metarhodopsin II and binding of G-protein.

The protein-detergent interaction in rhodopsin-detergent micelles has been investigated by using formation of metarhodopsin II (MII) as a monitor. Two detergents of different structural rigidity have been applied. One of them is [3-(lauroyloxy)propyl]phosphorylcholine, which has a high conformational flexibility in its hydrophobic moiety like most of the known detergents for rhodopsin. This deoxylysolecithin was originally designed as a detergent for membrane proteins by Weltzien [Weltzien, H. U. (1979) Biochim. Biophys. Acta 559, 259-287]. The other detergent, which is highly rigid in its hydrophobic part, has been developed for this study. It consists of a biphenyl derivative and a hydrophilic octaethylene oxide group. Both the formation kinetics of MII and the position of its equilibrium with its tautomeric form, metarhodopsin I (MI), strongly differed in the deoxylysolecithin and biphenyl detergent. Deoxylysolecithin caused very fast MII formation and shifted the equilibrium strongly to MII, like other detergents with alkyl chains as the hydrophobic part. In the biphenyl detergent, however, formation of MII was slow and the MI/MII equilibrium similar to that in the native system. For rhodopsin reconstituted in lipid bilayers, normal MII formation requires a well-adjusted fluidity of the hydrocarbon environment of the protein [Baldwin, P. A., & Hubbell, W. L. (1984) Biochemistry 24, 2633-2639], which was explained by an appropriate interfacial pressure at the protein-lipid interface. Extension of this concept would indicate that in the micellar core a degree of fluidity comparable to that of the disk membrane is just achieved with the highly rigid biphenyl structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Immunohistochemical studies with antibodies to myosins from the cytoplasm and membrane fraction of human blood platelets.

Antibodies were raised to myosins extracted from the cytoplasm and solubilized membranes of human blood platelets. Both antibodies had similar titers as shown by enzyme-immunoassay and bound to the same sites as shown by immunohistochemistry. They were specific for cytoplasmic myosins (e.g., in human white blood cells, platelets and fibroblasts and rat endothelial cells). They showed no crossreaction with human or rat smooth muscle.

Animals↗
PubMed1985

7-substituted-4-hydroxyquinoline-3-carboxylic acids as inhibitors of dehydrogenase enzymes and of the respiration of Ehrlich ascites tumor cells: multivariate analysis and quantitative structure-activity relationship for polar substituents.

The inhibitory activities of a set of nine 7-substituted-4-hydroxyquinoline-3-carboxylic acids against three dehydrogenase enzymes and one whole cell system (Ehrlich ascites tumor cells) have been subjected to principal component analysis. The results clearly indicate that activity against the whole cell test system cannot directly be attributed to inhibition of the enzymes evaluated. The enzyme systems are reflected by the first component that can be identified with polar and steric parameters while hydrophobic effects are absent. The second component is entirely due to the inhibition of ascites cell respiration that depends primarily on hydrophobicity.

Analysis of Variance↗
PubMed1985

Substructural QSAR approaches and topological pharmacophores.

For large and diverse data sets, simple QSAR methods based on linear and additive models can no longer be applied. In such cases topological methods using descriptors directly derivable from two-dimensional chemical structures provide a useful alternative. The results of such analyses can be used for lead optimization, to guide biological testing and even aid in the design of novel compounds. Various types of topological descriptors and algorithms are briefly discussed. Which of those is to be selected depends on the objective of the investigation and the properties of the data set. Two new methods, LOGANA and LOCON, are discussed in some more detail. With the help of these methods, substructural patterns ("topological pharmacophores") characteristic of compounds possessing a certain biological property can be evaluated. Both methods are designed in such a way that full use can be made of the data handling capacity of computers while maintaining an optimal impact of the experience of the researcher. They are model-free and do not require any mathematical knowledge. While LOGANA deals with semiquantitative or even qualitative biological data, LOCON can be applied to activity data on a continuous scale. The basic procedure in both cases consists in the stepwise combination of substructural descriptors by the logical operations "and," "or" and "not." With a simple example the utility of the methods is demonstrated.

Amides↗
PubMed1979

Discriminant--analytical investigation on the structural dependence of hyperglycemic and hypoglycemic activity in a series of substituted o-toluenesulfonylthioureas and o-toluenesulfonylureas.

The influence of a series of substituted o-toluenesulfonylthioureas and o-toluenesulfonylureas on the level of blood sugar was investigated in rats. According to the observed response the compounds were divided into three classes corresponding to hypoglycemic, hyperglycemic, and no activity. The distribution of the compounds over these classes can be described by discriminant functions using substituent constants, RM values, and indicator variables. Most important for the separation of classes are hydrophobic and/or steric properties as well as the presence or absence of the thiomide group. The results indicate that two different mechanisms of action with opposite effect overlap in the case of the series studied.

Animals↗
PubMed1979

On the interpretability of quantitative structure-activity relationships (QSAR).

QSAR are a powerful tool to obtain information on the molecular mechanism of drug action as well as on properties of receptors. They can be evaluated at different levels of sophistication using different parameters to describe physical chemical properties of the drugs and different mathematical methods. In this presentation only QSAR at the level of extrathermodynamic parameters will be considered. Interpretation of QSAR is always connected with two basic questions: 1) Which requirements must be met in order to get meaningful (interpretable) QSAR and what can be done to satisfy these requirements? 2) What information can be gained (and in which way) from QSAR? Some of the most important aspects of these questions to be discussed in this paper are: 1) Interrelationships between parameters and the separability of hydrophobic, electronic and steric effects. 2) Description of hydrophobic interactions. 3) Separation of hydrophobic effects connected with transport and hydrophobic bonding. 4) Estimation of the biological point of attack. 5) Selection and informational content of biological response data. Factor analysis will be shown to be a useful data preprocessing step allowing one to systematize data and to recognize and to eliminate collinearities. Another multivariate method, principal component analysis, may be used to separate pharmacokinetic and pharmacodynamic effects.

Biological Transport↗
PubMed1979

Hydrophobic binding of phenoxyacetic and phenylacetic acids to horseradish peroxidase and human serum albumin: structure-activity relationships.

Studies of protein binding in homologous series of drugs are of great interest for drug research. Apparent binding constants of phenoxyacetic and phenylacetic acids to horseradish peroxidase and to human serum albumin are evaluated by NMR studies and an optical method. These constants are good parameters to describe hydrophobic interactions, and the results are in a good agreement with our protein binding model described previously.

Chemical Phenomena↗
PubMed1978

Antiviral activity of dipyridamole derivatives.

Among 46 novel pyrimido [5.4-d] pyrimidine derivatives, 26 compounds were found to exhibit antiviral activity as revealed in a test programme against Mengo, Coxsackie B1, fowl plague, vaccinia and pseudorabies viruses, as concerns inhibition of plaque formation and of infectious virus yield. Attempts to disclose structure-activity relationships by discriminant analysis pointed to a possible importance of hydrophobic substitution for the antiviral effectiveness against Mengo virus of the derivatives investigated.

Antiviral Agents↗
PubMed1978

A simple method to obtain an approximate solution of the Free-Wilson model.

A method is proposed which yields an approximate solution of the Free-Wilson model very rapidly without using a computer. Although the resulting group contributions are numerically somewhat different from the exact Free-Wilson solution they correctly reflect the relative order of the substituents with respect to their effect on biological activity within each position as well as the relative importance of different positions. Thus, the approximate results can well be used to select the most promising candidates for further synthesis and testing.

Antimalarials↗
PubMed1977

[Nitrogen utilization and xanthan production by Xanthomonas campestris].

In media with mixed nitrogen sources (nitrate plus yeast extract) a three auxic growth is observed. The first growth phase is characterized by preferential utilization of the amino acids of the yeast autolysate and the utilization of only small amounts of nitrate. During the second growth phase nitrate is preferentially utilized. In the third phase there is only growth without dividing of cells and the accumulation of xanthan takes place. The change from growth by dividing to growth without dividing means a change from balanced to unbalanced growth. It is proposed that xanthan production is connected with unbalanced growth.

Amino Acids↗