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Biomedical subjects

R Neubert

Publications and source records attributed to R Neubert.

At least 109 records · Page 6Linked to original sources
PubMed1985

[Comparison of various methods for the identification of pneumococci based on optochin sensitivity].

The sensitivity against optochin of 491 strains of Streptococcus pneumoniae respectively alpha-haemolytic Streptococci was tested in optochin-plate-method and in the diffusion-test. Discs impregnated and used in wet condition and dry discs prepared in one of the participating laboratories were equal in their efficiency. The differentiation of Streptococcus pneumoniae and alpha-haemolytic Streptococci is possible by the disc-diffusion method using the following limit of inhibition zone. Streptococcus pneumoniae diameter of inhibition zone greater than 15 mm alpha-haemolytic Streptococci diameter of inhibition zone 0-15 mm The industrial production of optochin-discs can be recommended.

Bacteriological Techniques↗
PubMed1985

[Dissolution processes and surface changes. 3. Determination of the surface with the BET process].

Two methods are demonstrated for the determination of the surfaces of solid substances by the BET-method. Using a newly constructed apparatus substances with high specific surfaces can be determined by the two-point-method with a good precision. For the determination of pulverous drugs we used the one-point-method proposed by Haul and Dümbgen [2] improving it in calibration und practicability.

Chemistry, Pharmaceutical↗
PubMed1985

[Dissolution processes and surface alteration. 4. Determination of the "effective" surface].

A method is described for measuring the "effective" surface of a drug by means of dissolution parameters using the Paddle-model or a resorption-model respectively. The obtained values were compared with the specific surface which was determined by BET-technique. The "effective" surfaces obtained by means of the dissolution parameters are smaller than those determined BET-technique.

Diffusion↗
PubMed1984

[Drug permeation through artificial lipid membranes. 17. The mechanism of ion pair transport].

The transport of ionized drugs across lipoid membranes can be increased considerable by lipophilic counter ions. This is caused by an increased lipophilicity of the ion pair which is formed between the ionized drugs and the lipophilic counterion. Caused by their very strong solubility in the membrane the lipophilic counterions accumulate and act like a carrier for the ionized drugs. Then the necessary compensation of the charges can take place by protons or other suitable ions of the used solution.

Biological Transport↗
PubMed1982

[Feasibility of the in vitro evaluation of bioavailability. 3: Method of operation of a newly-developed absorption model and results obtained with it].

In connection with the function of a newly constructed absorption model the problem of interpretation of values obtained by models in regard of bioavailability is discussed. Wrong interpretations can be obtained if nonanalogous values are compared. An interpretation is proposed to calculate a value which is analogous to the relative bioavailability (calculated bioavailability). The efficiency of the absorption model and of the interpretation method is demonstrated by three examples of preparations of phenytoin, digoxin and chloramphenicol. We compared these results with the bioavailability of these preparations and we found a good correspondence.

Absorption↗
PubMed1980

[Studies on the E rosette test (author's transl)].

The number of T lymphocytes in the peripheral blood of normal subjects and patients with bronchial carcinoma was determined by using the E rosette test. In a comparative study we counted the "total" rosette forming cells and the "active" rosette forming cells using a lymphocytes-sheep red cells-ratio (Ly-SRBC-R) of 1:8 and 1:40. The numbers or rosettes in the two test systems are in correlation with the Ly-SRBC-R despite other differences in the techniques. -A significant difference was determined between normal subjects and patients with the "active" rosette test only with a L-SRBC-R of 1:40. By contrast the values with the L-SRBC-R of 1:8 were not very different between the two groups. -Also the number of "total" rosettes was significantly different between blood donors and carcinoma patients, using the L-SRBC-R. 1:40. -These results are not of direct clinical relevance, because the values of normal subjects and carcinoma patients are overlapping.

Bronchial Neoplasms↗
PubMed1980

[Drug permeation through synthetic lipid membranes. Part 10: The effects of diffusion layers on the permeation process (author's transl)].

Two different processes take their courses during the permeation of substances through lipid membranes. The substance must pass across the diffusion layers on the membranes and also across the lipid barrier proper. The effects of these two processes on the permeation vary with the kind of the membrane and of the substance as well as with the diffusion layer thickness which is determined by the intensity of movement. Correlations have been established which permit to calculate diffusion layers, membrane permeation coefficients, and also diffusion coefficients in the diffusion layers. Thus have been provided the prerequisites for the comparison of results obtained on using different model parameters.

Diffusion↗
PubMed1980

[Drug permeation through synthetic lipid membranes. Part 13: The effects of tensides on the permeation of ionized drugs (author's transl)].

The permeation of substances present in the ionized form is most markedly affected by tensides containing ions of opposite sign. These tensides produce a considerable increase in permeation. The effect of micelle formation will become evident only if the transport of the free drug through the membrane is more rapid than the release of the drug from the micelles. If the concentrations of nonionic tensides are less than the critical micelle concentration, a permeation increase occurs which is presumably caused by a reduction of the surface tension of the membrane.

Buformin↗
PubMed1978

[Determination of the sensitivity of mycobacteria to pyrazinamide and nicotinamide (author's transl)].

Since pyrazinamide (PZA) has had a come-back in therapy of tuberculosis a simple and reliable method for sensitivity tests has been necessary. A comparison of resistance tests to PZA in acid Löwenstein-Jensen-medium and in fluid medium with those to nicotinamide (NSA) showed a clear superiority of the NSA method, recommended by BRANDER. Also in routine sensitivity tests the use of NSA instead of PZA has stood the test. Another advantage of the method is the possibility to integrate it in the simplified proportion method without any additional work.

Drug Resistance, Microbial↗