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Biomedical subjects

H Renner

Publications and source records attributed to H Renner.

At least 73 records · Page 4Linked to original sources
PubMed1977

[Radiosensitivity of lymphocyte stimulation].

Experiments on radiosensitivity of lymphocyte stimulation in vitro and in vivo are described. Mainly the effects on DNA-synthesis and mitotic activity were measured. The effects of delay and inhibition are not specific for stimulated lymphocyte populations, they are common radiobiological characteristics of stimulated proliferation in contrast to spontaneous proliferation. Cells under stimulated proliferation are more radioresistant than the same cells without stimulation or other cells under spontaneous proliferation. In these basic and additional experiments lymphocyte stimulation proved to be a good radiobiological model system.

Animals↗
PubMed1977

[Radiation sensitivity of lymphocyte stimulation. 1. Experiments on in-vitro sensitivity of cell number and mitosis activity].

Radiation-induced transformations of stimulated lymphocytes are not to be regarded as characteristical responses of lymphocyte populations as such, but represent general radiobiologic principles of the stimulated proliferation. Thus, basic problems of stimulated proliferation in comparison with a spontaneous quick proliferation of normal cellular systems in vitro have chiefly been studied by means of two stimulation models in vivo, the model of liver regeneration following partial hepatectomy and the model of beta stimulation of the salivary glands. The radiosensitivity of the lymphocyte stimulation in vitro as well as in vivo has been analyzed especially with regard to its quality as a model. The task was approached methodically by: a) Determination in vitro of the number of cells (66 cultures), b) morphological analysis of the mitotic activity in vitro (270 cultures), c) measurements in vitro with 3h-thymidine of the DNA synthesis using liquid scintillation counts (more than 3000 cultures), d) measurements in vitro with 3H-thymidine of the DNA synthesis using autoradiography (66 cultures), e) determination in vivo of the DNA synthesis by means of the incorporation of 131I-desoxyuridine into the mouse spleen (investigation with 100 mice). For a model of lymphocyte stimulation mainly that of PHA stimulation in vitro and in vivo of T-lymphocytes was chosen, supplemented by the one of PWM stimulation of T- and B- lymphocytes for measuring in vitro the DNA synthesis. In particular, influence of in vitro irradiation upon several variables of the stimulation model was investigated in order to examine the methodics critically: a) During the determination of the mitotic index too short an acbition by partial synchronization effects within the dose range of 10 to 500 R. The chronological analysis of the process during determination of the mitotic activity is indispensable in order to differentiate the mitotic inhibition from a mitotic delay in the case of high doses, b) For the determination of the DNA synthesis the concentration of stimulative PHA or PWM has no substantial influence on the radiation-induced inhibition effect; the constancy of serum percentage in the culture system, however, is an important condition for comparability of different experiments. Moreover, only a short period of labeling with 3H-thymidine, lasting 1.5 to 12 hours, interferes with radiation-induced inhibition of the DNA synthesis, this probably being also due to partial synchronization effects within the dose range of 10 to 500 R. c) In order to determine the DNA synthesis wether in vitro or in vivo, a chronological analysis is a condition indispensable for differentiation between the three factors involved: Delay of DNA synthesis, blockage of DNA synthesis, and inhibition of the proliferation...

Adult↗
PubMed1977

[Radioprotection during clinical and laboratory utilization of tritium-labeled thymidine (author's transl)].

In view of the new prescriptions for radioprotection of the Helevetic Confederacy (Eidgenössische Strahlenschutzverordnung) the problems of radioprotection connected with utilization of the pure beta-ray emitter tritium are exposed, since the latter frequently is used as a marker substance in biomedical investigations. Inorganic tritum is regarded as the least toxic radionuclide. With tritiated thymidine, very often used for study of cell proliferation and cellular kinetics because of its incorporation into DNA, the radiation risk has to be considered quite differently. Its radiotoxicity is estimated to be superior by a factor up to thousand. The increased risk, thus resulting, is discussed with regard to the findings by animal experimentation and to the toxicity in man. Practical recommendations for the use of tritium-thymidine are given.

Animals↗
PubMed1976

[Influence of radiotherapy on lymphocyte stimulation].

More than 300 lymphocyte cultures of 12 patients with seminomas were examined during the prophylactic radiotherapy and, in several cases, during an extended period until 20.5 months after the end of the treatment. The object of this study was to find out by measuring the capacity of the lymphocytes to be stimulated in vitro wheather they could be damaged by the radiotherapy. Among other reasons, the above mentioned patients were chosen because they had been submitted to irradiations of vast volumes of lymphatic tissues at a uniform focal dose of 4000 rad. The different opinions expressed in the literature (stimulation decreassed resp. increased resp. unchanged) are reflected by our results in such a way that we did not find a qualitative loss of the capacity to be stimulated cultures. The problem of the different opinions about the capacity of lymphocytes to be stimulated after a radiotherapy appears; among other things, to be based on different examination methods. According to these methods- morphological determination of the relative number of lymphoblasts, synthesis of DNA by fluid scintillation counting, or determination of the number of surviving cells in vitro -different results are obtained. It seems not possible to use the lymphocyte stimulation in vitro as a method of testing clinical sideefects occuring during the characteristics of immunity and radiation biology are not differentiated in a more precise manner.

Adult↗
PubMed1975

[Lymphocyte sensibilisation by fetal antigens in man after immunisation with xenogeneic fetal cells and with malignant tumors (author's transl)].

Specific lymphocyte sensibilisation in man can be shown one to four months after injection of xenogeneic fetal cells by means of in vitro lymphocyte stimulation by the previous injected lyophilised fetal antigens. Adult lyophilised xenogeneic cells demonstrate no stimulatory effect. In the same test positive lymphocyte stimulation against lyophilised fetal cells can be demonstrated in about 50% of a group of patients with malignant tumors. These preliminary findings could be a possible link in evaluating the effects of fetal cells as a form of tumor-immunotherapy in man.

Adult↗
PubMed1975

[Demonstration of skeletal metastases using the bone marrow biopsy and the radiographic skeletal survey within the scope of pretherapeutic diagnosis in bronchial carcinoma].

In the course of pretherapeutic diagnostics of bronchogenic carcinoma, bone marrow biopsy revealed in ten out of 116 patients (9%) and radiographic skeletal survey in 16 out of 62 patients (26%) metastases to the skeleton. The two methods are complementary with reference to anaplastic and oat-cell carcinomas. On account of our experiences, we never fail to control the skeleton before the beginning of a local curative therapy in bronchial carcinoma.

Adenocarcinoma↗
PubMed1975

[Fetal tumor antigens].

A wide spectrum of fetal antigens is found not only in fetal cells but also in tumor cells. These substances are termed onco-fetal antigens. One group out of these antigens has developed special diagnostic interest and importance, first of all the carcino-embryonic antigen (CEA) in adenocarcinomas of the gastrointestinal tract. Another class of fetal antigens consists of tumor-assoicated membrane-antigens against these the organism may develop a cytotoxic reaction and in the long run, may repulse the tumor like an incompatible graft. The verification of this second group was possible by means of various cross reactions. These latter fetal antigens eventually may be utilized for purposes of immunological prophylaxis and therapy.

Animals↗