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Biomedical subjects

R Schmidt

Publications and source records attributed to R Schmidt.

At least 685 records · Page 38Linked to original sources
PubMed1982

Cultures of zona ependyma cells of goldfish brain: an immunological study of the synthesis and release of ependymins.

Two proteins (ependymins beta and gamma) localized within specific cells in the zona ependyma of goldfish brain were identified in previous studies in our laboratory as extracellular factors whose metabolism was highly increased by the acquisition of new patterns of behavior. Methods for growing zona ependyma cells in culture were developed to determine if cells within this tissue could synthesize and release the ependymins into their extracellular environment. Dissociated cells from zona ependyma were grown as primary monolayer cultures on polylysine-coated slides. The cultures survived for at least 4-5 weeks, forming an intricate network of interconnecting processes. These contained many cell types, several of which retained their in vivo immunohistochemical properties. Specific populations of cells staining with antisera to nerve growth factor, glial fibrillary acidic protein, and ependymins beta and gamma were present. Radioimmunoassay, immunoelectrophoresis data, and labeling experiments indicate that cells within the cultures can synthesize the ependymins de novo and release them into their extracellular environment. These results are consistent with the hypothesis that the ependymins might function as extracellular factors which mediate the behaviorally induced plasticity of the goldfish CNS. In this respect they resemble other "protein factors" which stimulate the growth and morphological differentiation of nervous system cultures.

Animals↗
PubMed1982

Induction of differentiation in human promyelocytic leukemia cells by tumor promoters.

12-)-Tetradecanoylphorbol-13-acetate (TPA), the prototype polyfunctional diterpene ester tumor promoter of two-step carcinogenesis in mouse skin, induced differentiation of human promyelocytic leukemia cells (HL-60) in culture. Differentiation of HL-60 cells was characterized by increased phagocytosis, increased lysozyme activity (EC 3.2.1.17) in the growth medium, and changes in morphology to those characteristics of more mature cells resembling macrophages. Many of the cells treated with TPA became aggregated, attaching firmly to culture flasks. The average intracellular myeloperoxidase activity (EC 1.11.1.7) per cell decreased during induction of differentiation by TPA. It was also found that TPA enhanced, rather than inhibited, differentiation of HL-60 cells induced by DMSO. In addition to TPA, several polyfunctional diterpene esters of the tigliane, ingenane, and daphnane type have been tested for their ability to induce morphological and functional changes of HL-60 cells. The activities of the compounds to induce these changes correlated well with their activities as tumor promoters in two-step carcinogenesis in mouse skin. In particular, half the concentrations required for induction of adhesion of the cells to flasks were roughly correlated to the potency of these compounds as tumor promoters. Among the compounds tested, phorbol-12,13-didecanoate (PDD), ingenol-3-hexadecanoate, Pimelea factor P1 and Pimelea factor P2 were as active as TPA, while 4-O-methyl-TPA and 4 alpha-PDD were much less active. Phorbol and ingenol were totally inactive up to a concentrations 10,000-fold higher than that of TPA.

Cell Adhesion↗
PubMed1982

Prognostic value of the electroencephalogram in neonatal asphyxia.

In order to determine whether an EEG early in the course of asphyxia neonatorum is of any more value than the neurological examination in predicting outcome we reviewed case histories of 38 infants with asphyxia neonatorum. The EEG background activity was valuable in predicting outcome. Normal and maturationally delayed EEGs were associated with normal outcomes while low voltage, electrocerebral inactivity and burst suppression EEGs were highly correlated with severe neurological sequelae. Epileptiform activity was not as predictive of outcome as background activity. Although initial normal neurological examinations were associated with normal developmental and neurological outcomes, moderately and severely abnormal infants had more variable courses. A single EEG done early in the course of asphyxia neonatorum is a more sensitive predictor of outcome than the neurological examination.

Asphyxia Neonatorum↗
PubMed1982

Spectroscopic intercomparison at the German neutron therapy centers.

An intercomparison of neutron dosimetry at the German neutron therapy centers at Hamburg, Heidelberg and Essen has been performed in 1979 and 1980. This intercomparison was undertaken to compare the experimental procedures and techniques for fast neutron dosimetry applied by each group. Because of the energy dependence of the dosimeters, spectroscopic investigations were performed at positions in the phantom identical to those applied during the dosimetric measurements. A description of the experimental procedures and environments is given. The measured neutron spectra are presented and discussed with respect to the changes at different positions in the phantom. Individual kerma-ratios are calculated from the neutron and photon energy distributions. The comparison of these kerma-ratios gives considerable differences in values that are used with neutron-insensitive ionization chambers. We recommend that individual generated kerma-ratios should be applied for ionization chamber dosimetry.

Light↗
PubMed1982

Serological investigation of horse sera for antibodies against mycoplasmas and acholeplasmas.

Sera from horses with respiratory disease (RD) have been investigated using the complement fixation test, indirect hemagglutination test, enzyme immune assay, and the metabolic inhibition test, and sera from mares after abortion, using the complement fixation test, indirect hemagglutination test and enzyme immune assay, for antibodies against Mycoplasma equirhinis, M subdolum, M. equigenitalium, M. pulmonis, M. felis, Acholeplasma laidlawii, A. hippikon and A. equifetale. Antibodies were found against all mycoplasma and acholeplasma species tested, more often against acholeplasmas. The antibody pattern was quite similar for horses with RD and for mares after abortion. The results of the four serological tests performed showed only a limited correlation and the percentage of sera with antibodies detected by the four tests used differed widely.

Abortion, Veterinary↗
PubMed1982

The use of TNP-conjugated polyacrylamide beads in a C1q binding inhibition test for circulating immune complexes.

A new assay for the detection of circulating immune complexes is described. It is based on the same principle as the C1q deviation test: the binding of radiolabelled C1q to a solid phase is inhibited by immune complexes. Trinitrophenylated polyacrylamide beads are used as a stable C1q-reactive solid phase in our test. Aggregated IgG in normal serum could be detected by this method to a minimum concentration of about 10 microgram/ml. The test was used to quantitate circulating immune complexes in sera of patients with glomerulonephritis, liver diseases, lymphoma, and myeloid leukemia. The results are compared and correlated with those obtained by the C1q binding assay for the same sera.

Acrylic Resins↗
PubMed1982

Tumor-promoting diterpene esters prevent macrophage activation and suppress macrophage tumoricidal capacity.

The efficacy of varied diterpene ester type tumor promoters in suppressing the acquisition as well as the manifestation of cytolytic activity by macrophages was investigated. These mechanisms, believed to be basic to natural antitumor resistance, were markedly suppressed not only by the phorbol ester, TPA, but also by several other tumor promoters of the polyfunctional diterpene ester type covering tigliane, ingenane, and daphnane derivatives. The promoters were particularly effective in preventing the lymphokine-induced enhancement of natural cytolytic activity in resting macrophages. Moreover, the same promoters suppressed the manifestation of cytotoxicity by previously activated macrophages. Their influence on the effector phase was less pronounced than on the activation phase. In sharp contrast, typical solitary carcinogens of the polycyclic aromatic hydrocarbon type exerted little or no activity in the macrophage test systems. Since TPA had already been shown to suppress the natural killer activity in vitro and to abrogate host tumor resistance in vivo, the present findings lend further support to the interpretation that tumor promoters, apart from directly stimulating the outgrowth of transformed cells, may function via interference with natural antitumor effector systems.

Animals↗
PubMed1982

Ultrastructural alteration of the alveolar epithelium after exposure to organic solvents.

Adult rats were exposed to the solvents n-hexane and methylethylketone (MEK) in different concentrations. Lung tissue was examined systematically after various periods by electron microscopy. The direct toxic effect to pneumocytes could be demonstrated as definite regressive alterations, such as fatty degeneration and changes of lamellar bodies of type II pneumocytes as well as increased detachment of cells. Besides these findings, after chronic inhalation of solvents conspicuous aggregation of lamellar discharge material of type II pneumocytes can be seen, and probably, as a result of an irritated fat metabolism, large lysosome-like bodies with densely packed lipid material appear in type I pneumocytes. The most distinguished changes could be demonstrated after exposure to a mixture of n-hexane and MEK, while they were less obvious after n-hexane alone. The observation suggests a profound enzymatic irritation of metabolism.

Animals↗
PubMed1982

[Staining properties and applicability of spectrally pure thionine and its isomeres (author's transl)].

Paraffin-embedded human and animal tissues were stained with spectrally pure thionine, 1,3-diaminophenthiazoniumchlorate and 1,7-diaminophenthiazoniumperchlorate. They were examined by light microscopy to determine their applicability in histologic diagnosis. Furthermore the effect of salts and of the type of dye solvent on the staining properties of histological preparations was being investigated. Essentially the following results were obtained: 1. All 3 dyes can be applied rapidly and unproblematically on all types of tissues. Under standardized conditions, i.e. dye concentration, length of staining time and kind of staining procedure, the results are reproducable. 2. Thionine and its isomeres, being basic dyes, demonstrate a special affinity for nuclei, but also do stain cytoplasm sufficiently well to make counter-staining methods unnecessary. 3. Thionine -- in contrary to its isomeres -- reacts metachromatically with certain cellular structural elements, i.e. RNA, acid mucopolysaccharides, mucin. This property aids in morphological diagnosis and additionally enlightens certain activity states. 4. Addition of salts interferes with the staining procedure. 5. Water has special significance as solvent. Furthermore the appearance and function of metachromasia, the influence of ethanol on the metachromatic reaction, the mode of action of anorganic salts are being discussed as well as the reciprocal action of biologic substrates with the dyes having been incorporated by them.

Animals↗
PubMed1982

[Audiometric findings in legasthenics (author's transl)].

The audiological findings in 150 legasthenics are discussed and a review of the literature is given. The E.R.A. and Feldmann's dichotic test did not reveal any characteristic changes in our patients. However, a binaural audiovisual test using normal and synthesized stammered words alternatively showed a statistically significant impairment in recognizing the presented material in legasthenics compared to less gifted individuals of the same age. The results in normal children varied according to age. It might therefore be possible to diagnose legasthenics with this test in combination with an intelligence test in pre-school age.

Audiometry↗
PubMed1982

[Relations between acanthosis nigricans benigna and pseudoacanthosis nigricans].

A 37-year-old man is reported who, as a schoolboy and during puberty, showed the clinical aspects of acanthosis nigricans benigna. In correlation with an obvious obesity the picture has meanwhile developed into pseudoacanthosis nigricans. On the basis of this case the delimitating criteria of the various acanthosis nigricans subgroups and their etiologic factors are discussed.

Acanthosis Nigricans↗
PubMed1982

Triple chamber technique for thermal neutron dose measurements in fast neutron beams.

Collimated fast neutron beams used in radiotherapy are always contaminated with photons and thermal neutrons. From foil activation measurements the relative dose contribution of thermal neutrons to the absorbed neutron dose in different depths in a tissue equivalent phantom was determined. The sensitivities of a TE-Chamber, a GM-counter with a 6Li-shield and an unshielded GM-counter to fast neutrons, thermal neutrons and photons are presented. The triple chamber technique using these three devices is compared to foil activation technique with respect to the determination of relative thermal neutron depth dose curves. Finally the triple chamber technique is applied for the determination of depth dose curves of fast neutrons, thermal neutrons and photons in a solid TE-phantom.

Fast Neutrons↗