The fate of cells with chromosome aberrations after total-body irradiation and bone marrow transplantation

Cytogenetic studies were done on bone marrow cells and peripheral lymphocytes of four patients (three with acute nonlymphocytic leukemia, one with aplastic anemia) at various intervals up to 861 days after total-body X irradiation (TBI) at doses between 4.5 and 10 Gy (450-1000 rad) followed by syngeneic or allogeneic bone marrow transplantation. Whereas no radiation-induced aberrations could be found in the bone marrow, apart from a transient finding in the patient with the lowest radiation dose, aberrant metaphases were seen in the peripheral lymphocytes of three patients in the range from 2.5 to 46% even at 861 days after the exposure. There were no demonstrable aberrations related to TBI in the only patient developing graft-versus-host disease. The dicentric yield as determined in the aberrant metaphases with 46 centromeres ranged between 3.4 +/- 1.3 and 4.9 +/- 0.4. In one patient it was demonstrated by BUdR-labeling that after 10 Gy (1000 rad) TBI the surviving and heavily damaged lymphocytes can go into cell cycle and reach at least the third mitosis. The percentage of aberrant cells diminished by about 25% at each mitotic division.     

Kinematographische Dokumentation einer amitotischen Zellteilung

Summary Identification of argyrophilic cells, in pancreatic islets of normal rabbits, is accomplished by light and electron microscopy in osmium-fixed plastic-embedded tissues.Fixative, pretreatment and pH of silver nitrate solution were essential for the light microscopic study to reveal argyrophilic cells in osmium-fixed plastic-embedded pancreatic islet tissue. The best result was obtained with Dalton's osmium fixation and buffered silver nitrate methanamine solution at pH 9.O. The cytoplasmic granules of argyrophilic cells generally are densely packed but some of the cells show only sparse silver impregnated granules in the cytoplasm. Occasionally there are some non-argyrophilic granular cells in which, after silver impregnation, the cytoplasm appears clear. There are three kinds of cells in the pancreatic islets, i.e., argyrophilic granular cells, non-argyrophilic granular (clear) cells, and beta cells (situated centrally in the islet and stained light yellow in silver impregnated sections).The cells known as argyrophilic cells in light microscopy can be identified as alpha cells in electron micrographs by comparison of consecutive sections of the same cell.The author would like to express his appreciation to professor Roy C. Swan for his generous guidance.     

Stem cells from peripheral blood and bone marrow: a comparative evaluation of the hemopoietic potential in the dog

The kinetics and pattern of hemopoietic recovery after supralethal total-body irradiation (TBI) were compared after transfusion of cryopreserved autografts derived from peripheral blood and bone marrow. Fractionated TBI was given in three doses of 6 Gy each at intervals of 48 h. Grafts of peripheral blood mononuclear cells (MNC) were collected by means of continuous-flow centrifugation and by using the mobilizing agent, dextran sulphate. Autografts were adjusted to contain equal numbers of committed progenitor cells (CFU-GM). Dogs grafted with blood-derived MNC (group A) and with MNC from bone marrow (group B) all received about 1 X 10(5) CFU-GM per kg body weight. In all dogs consistent hemopoietic engraftment was achieved. Comparing the pattern of regeneration of the granulocytes, group A dogs showed a significant regeneratory advantage over group B dogs, particularly during the first 20 days after transplantation. Lymphoid recovery was more rapid in group A until day 14. In both groups, blood lymphocytes remained below normal values beyond day 100. The regeneration patterns of the platelets and reticulocytes revealed no significant differences. These results are in agreement with the hypothesis that there are differences in the relationship between CFU-GM content and hemopoietic potential of autografts from different sources.     

Laser pyrolysis products-genotoxic, clastogenic and mutagenic effects of the particulate aerosol fractions

Laser therapy has gained wide acceptance and application in many medical disciplines. Nevertheless, during surgical procedures, the thermal destruction of tissue creates a smoke plume. Recent research data indicate that pyrolysates liberated during vaporisation of tissue induce DNA damage. However, assessing potential health hazards during medical laser treatment requires comprehensive insight into the cytotoxic, genotoxic, clastogenic and mutagenic capacity of laser pyrolysis products (LPP). Therefore, the aim of this study was to evaluate the cytotoxic, genotoxic, clastogenic and mutagenic potential of substances resulting from laser irradiation. Four different types of porcine tissues were irradiated with a surgical CO2 laser, the aerosols were sampled under defined conditions and subjected to the SCE test, micronucleus test and the HPRT test. The results showed that the pyrolysis products are strong inducers of cytotoxic effects. The pyrolysis products induced positive effects in the SCE test, micronucleus test and the HPRT test. The ability and extent to induce genotoxic and mutagenic effects turned out to be dependent on the type of tissue that had been irradiated. In general, the effects were most pronounced with liver pyrolysate. In all test systems, a clear dose relationship could be established. In conclusion, we were able to prove that the particulate fraction of laser pyrolysis aerosols originating from biological tissues undoubtedly have to be classified as cytotoxic, genotoxic, clastogenic and mutagenic. Therefore, they could be potential health hazards for humans.     

SEARCH: a system for evaluation and archiving of radiation accidents based on case histories

Overexposure of humans to ionizing radiation has occurred worldwide in the past and will surely occur again in the future. In order to allow an effective radiation accident management, it is consequently necessary to be prepared for such emergency situations and to improve means and ways to help people suffering from radiation-induced health impairments. Such approaches should rely on knowledge and experience gained from previous radiation incidents. A prerequisite for any scientific evaluation and comparison of information related to radiation accidents is to collect data in a standardized way. Therefore, the SEARCH database (System for Evaluation and Archiving of Radiation accidents based on Case Histories) has been developed in our department and implemented as an Oracle 8.0 database containing to date more than 800 case histories. The use of this registry is so far limited to active contributors and requires each contributor to sign a cooperation agreement. More information is available under http://www.faw.uni-ulm.de/radmed/. Received: 7 February 2000 / Accepted: 8 May 2000     

Hematopoietic cell renewal systems: mechanisms of coping and failing after chronic exposure to ionizing radiation

On the occasion of the first international workshop on systems radiation biology we review the role of cell renewal systems in maintaining the integrity of the mammalian organism after irradiation. First, 11 radiation emergencies characterized by chronic or protracted exposure of the human beings to ionizing irradiation were “revisited”. The data provide evidence to suggest that at a daily exposure of about 10–100 mSv, humans are capable of coping with the excess cell loss for weeks or even many months without hematopoietic organ failure. Below 10 mSv/day, the organisms show some cellular or subcellular indicators of response. At dose rates above 100 mSv/day, a progressive shortening of the life span of the irradiated organism is observed. To elucidate the mechanisms relevant to tolerance or failure, the Megakaryocyte–thrombocyte cell renewal system was investigated. A biomathematical model of this system was developed to simulate the development of thrombocyte concentration as a function of time after onset of chronic radiation exposure. The hematological data were taken from experimental chronic irradiation studies with dogs at the Argonne National Laboratory, USA. The results of thrombocyte response patterns are compatible with the notion of an “excess cell loss” (compared to the steady-state) in all proliferative cell compartments, including the stem cell pool. The “excess cell loss” is a function of the daily irradiation dose rate. Once the stem cell pool is approaching an exhaustion level, a “turbulence region” is reached. Then it takes a very little additional stress for the system to fail. We conclude that in mammalian radiation biology (including radiation medicine), it is important to understand the physiology and pathophysiology of cell renewal systems in order to allow predicting the development of radiation induced lesions.     

Anti-Cancer Potential of MAPK Pathway Inhibition in Paragangliomas–Effect of Different Statins on Mouse Pheochromocytoma Cells

To date, malignant pheochromocytomas and paragangliomas (PHEOs/PGLs) cannot be effectively cured and thus novel treatment strategies are urgently needed. Lovastatin has been shown to effectively induce apoptosis in mouse PHEO cells (MPC) and the more aggressive mouse tumor tissue-derived cells (MTT), which was accompanied by decreased phosphorylation of mitogen-activated kinase (MAPK) pathway players. The MAPK pathway plays a role in numerous aggressive tumors and has been associated with a subgroup of PHEOs/PGLs, including K-RAS-, RET-, and NF1-mutated tumors. Our aim was to establish whether MAPK signaling may also play a role in aggressive, succinate dehydrogenase (SDH) B mutation-derived PHEOs/PGLs. Expression profiling and western blot analysis indicated that specific aspects of MAPK-signaling are active in SDHB PHEOs/PGLs, suggesting that inhibition by statin treatment could be beneficial. Moreover, we aimed to assess whether the anti-proliferative effect of lovastatin on MPC and MTT differed from that exerted by fluvastatin, simvastatin, atorvastatin, pravastatin, or rosuvastatin. Simvastatin and fluvastatin decreased cell proliferation most effectively and the more aggressive MTT cells appeared more sensitive in this respect. Inhibition of MAPK1 and 3 phosphorylation following treatment with fluvastatin, simvastatin, and lovastatin was confirmed by western blot. Increased levels of CASP-3 and PARP cleavage confirmed induction of apoptosis following the treatment. At a concentration low enough not to affect cell proliferation, spontaneous migration of MPC and MTT was significantly inhibited within 24 hours of treatment. In conclusion, lipophilic statins may present a promising therapeutic option for treatment of aggressive human paragangliomas by inducing apoptosis and inhibiting tumor spread.