Biomedical subjects
Publications and source records attributed to H Poppe.
A new continuous position marker for whole-body computed tomography marks the distance from an anatomical point or from a radiation field, the left side of the patient, and the zero level in front of or behind the CT-picture.
Various screening tests provide a detailed representation of fibrous dysplasia: thermography, scintigraphy, computer tomography, scanning electron microscopy, X-ray microanalysis, microradiography and fluorescence microscopy. The stationary nature of clinical and X-ray findings contrasts with the intensive structural changes that occur. The above-mentioned methods are examined with regard to differential diagnosis.
Diagnostic and differential diagnostic aspects of the known manifestations of histiocytosis X are discussed with respect to our own findings. It is our considered opinion that the term "histiocytosis X" should not be employed in isolation for diagnostic purposes. Rather, one should make an effort to designate the disease exactly in stating the prognosis for a particular patient. Both clinical and morphologic parameters must be considered in making this exact diagnosis.
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Phase systems using alkyl-modified silica as an absorbent, used as much and as a support for dynamically coated ion exchangers, were investigated for their capability in separating catecholamines and related compounds. Simple reversed-phase adsorption chromatography with C8-bonded silica is not able to separate these compounds very well because of (i) the very small retention of the more basic compounds in circumstances where the acidic compounds are well separated, (ii) bad peak shapes and (iii) low column efficiences, although the last drawback can be circumvented by the addition of inorganic anions to the eluent. The addition of a dynamically coated cation exchanger, sodium dodecylsulphate (SDS), to the eluent not only brings about drastic changes in the selectivity, but also makes available an additional degree of freedom for influencing the selectivity. The retention of the basic solutes increases upon addition of SDS and the retention becomes inversely proportional to the counter ion (Na+) concentration. Further, it was found that columns previously loaded with SDS can be used with SDS-free eluents when a pre-column, loaded with SDS, is used or with eluents containing a very small amount of SDS (less than 0.001%, w/v). These SDS-coated phase systems behave similarly to phase systems containing SDS in the eluent and show a better column stability and UV background.
A method for the concentration of dilute samples on a column and its application to the analysis of biomedical mixtures is described. Two columns are used, one for the concentration step and the other for the separation. The concentration column is used in the position of the loop in an injection valve. Concentration is effected by eluent switching. The influence of the chromatographic parameters such as capacity ratio and void volume on separation and detectability are described and the optimal choice of conditions is discussed. The method has been applied to the analysis of the cytostatic drug methotrexate. An octyl-modified silica was used as the stationary phase in the concentration column and a chemically bonded anion exchanger on silica in the separation column. The procedure shows good selectivity and precision. The detection limit corresponds to 2.10-8 M (9 ppb) in plasma, which is sufficiently low for therapeutic concentrations to be measured. An example of the use of the same stationary phase in both columns is given for the analysis of phenothiazines in blood, using alkyl-modified silica and electrochemical detection.
From the radiological point of view it can be concluded that: 1. Patients suffering from lung tumors usually seek treatment in an advanced stage of the disease. 2. In about one third of the cases, there is a manifestation of extrathoracic metastases already at the commencement of therapy. 3. Significant X-ray therapy depends on a) radiosensibility of the tumor to X-rays, b) the site and extent of the tumor. Although limited in its application, radiotherapy does not only improve the situation of the patient but also leads to a regression or temporary X-ray induced standstill of the growth of the tumor. However, if it is used as the sole treatment, it would scarcely lead to a permanent improvement. As recent advances in the treatment of lung tumors show, X-ray therapy combined with polychemotherapy will not only lengthen the survival time of the patient but will also improve the patient's life in general.
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A detector for liquid chromatography, based on anodic electrochemical oxidation at a glassy carbon electrode, is used in combination with reversed-phase liquid chromatography for the determination of the long-acting tricyclic psychotropic drugs fluphenazine and perphenazine in blood. Completely porous microparticulate silica material, modified so as to give a methyl silica, was used as the stationary phase and buffered mixtures of methanol and water as the mobile phase. The low detection limit and the selectivity of the coulometric detector made possible the determination of concentrations of 1-20 ppb of the compounds of interest. An extraction procedure was in order to obtain sufficient selectivity. Data for the precision, detection limit and yield of the extraction procedure are given. A number of serum levels of perphenazine after oral administration and of fluphenazine after i.m. doses of fluphenazine decanoate are stated.
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1. The symmetric interneuronal junctions (attachment plaques) of large axon terminals in the dorsal lateral geniculate body of the rat were studied, applying besides the conventional staining the block staining method with ethanolic phosphotungstic acid (E-PTA). 2. After staining these contact zones with E-PTA 3 main components become visible: the interior presynaptic layer, the intermembranous material and the postsynaptic layer. 3. As opposed to the asymmetric synaptic junctions the interior presynaptic layer is not divided into dense projections. 4. The intermembranous material consists of 2 median situated intracleft lines, which are more or less fused with each other. 5. The staining intensity of the paramembranous material of the symmetric junctions stained with E-PTA corresponds to the intensity of the material of the asymmetric synaptic junctions.
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