RENEB Inter-Laboratory Comparison 2021: The Dicentric Chromosome Assay.

After large-scale radiation accidents where many individuals are suspected to be exposed to ionizing radiation, biological and physical retrospective dosimetry assays are important tools to aid clinical decision making by categorizing individuals into unexposed/minimally, moderately or highly exposed groups. Quality-controlled inter-laboratory comparisons of simulated accident scenarios are regularly performed in the frame of the European legal association RENEB (Running the European Network of Biological and Physical retrospective Dosimetry) to optimize international networking and emergency readiness in case of large-scale radiation events. In total 33 laboratories from 22 countries around the world participated in the current RENEB inter-laboratory comparison 2021 for the dicentric chromosome assay. Blood was irradiated in vitro with X rays (240 kVp, 13 mA, ∼75 keV, 1 Gy/min) to simulate an acute, homogeneous whole-body exposure. Three blood samples (no. 1: 0 Gy, no. 2: 1.2 Gy, no. 3: 3.5 Gy) were sent to each participant and the task was to culture samples, to prepare slides and to assess radiation doses based on the observed dicentric yields from 50 manually or 150 semi-automatically scored metaphases (triage mode scoring). Approximately two-thirds of the participants applied calibration curves from irradiations with γ rays and about 1/3 from irradiations with X rays with varying energies. The categorization of the samples in clinically relevant groups corresponding to individuals that were unexposed/minimally (0-1 Gy), moderately (1-2 Gy) or highly exposed (>2 Gy) was successfully performed by all participants for sample no. 1 and no. 3 and by ≥74% for sample no. 2. However, while most participants estimated a dose of exactly 0 Gy for the sham-irradiated sample, the precise dose estimates of the samples irradiated with doses >0 Gy were systematically higher than the corresponding reference doses and showed a median deviation of 0.5 Gy (sample no. 2) and 0.95 Gy (sample no. 3) for manual scoring. By converting doses estimated based on γ-ray calibration curves to X-ray doses of a comparable mean photon energy as used in this exercise, the median deviation decreased to 0.27 Gy (sample no. 2) and 0.6 Gy (sample no. 3). The main aim of biological dosimetry in the case of a large-scale event is the categorization of individuals into clinically relevant groups, to aid clinical decision making. This task was successfully performed by all participants for the 0 Gy and 3.5 Gy samples and by 74% (manual scoring) and 80% (semiautomatic scoring) for the 1.2 Gy sample. Due to the accuracy of the dicentric chromosome assay and the high number of participating laboratories, a systematic shift of the dose estimates could be revealed. Differences in radiation quality (X ray vs. γ ray) between the test samples and the applied dose effect curves can partly explain the systematic shift. There might be several additional reasons for the observed bias (e.g., donor effects, transport, experimental conditions or the irradiation setup) and the analysis of these reasons provides great opportunities for future research. The participation of laboratories from countries around the world gave the opportunity to compare the results on an international level.

Exacerbation of acute inflammatory arthritis by the colony-stimulating factors CSF-1 and granulocyte macrophage (GM)-CSF: evidence of macrophage infiltration and local proliferation.

CSF-1 and GM-CSF have been implicated in the pathogenesis of rheumatoid arthritis. We report the effects of CSF-1 and GM-CSF in the development of an acute methylated bovine serum albumin (mBSA)-induced murine arthritis model. Examination of histopathological features revealed that the systemic administration of CSF-1 or GM-CSF following mBSA administration into the knee resulted in the exacerbation of arthritis. This included synovial hyperplasia and joint inflammation, most evident at 7 and 14 days post-mBSA administration, and the appearance of erosive pannus tissue. The exacerbation by CSF-1 and GM-CSF was not sustained but declined in incidence and severity by 21 days post-mBSA administration, similar to the effects of IL-1beta in this model, reported here and previously. Macrophages expressing Mac-2 and F4/80 were a prominent feature of the pathology observed, particularly the infiltration of Mac-2+ macrophages seen in all mice administered CSF-1, GM-CSF or IL-1beta. Present in inflamed knees was a locally dividing population of cells which included Mac-2+ and F4/80+ macrophages. These studies demonstrate that CSF-1 and GM-CSF can exacerbate and prolong the histopathology of acute inflammatory arthritis and lend support to monocytes/macrophages being a driving influence in the pathogenesis of inflammatory arthritis.

Erythrocyte antioxidant activity, serum ceruloplasmin, and trace element levels in subjects with alcoholic liver disease.

Erythrocyte antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) and reduced glutathione, serum ceruloplasmin, and serum trace elements (copper, zinc, iron, and selenium) related to antioxidant enzymes were assayed in subjects with alcoholic liver disease of different degrees of severity. The erythrocytes of subjects with moderate and severe alcoholic liver cirrhosis had an unbalanced antioxidant system (normal superoxide dismutase, low catalase and glutathione peroxidase activities, and low glutathione content). Serum ceruloplasmin levels were in the normal range. Levels of the serum trace elements zinc and selenium were significantly low in subjects with moderate and severe cirrhosis, whose red cell half-life was also significantly short, as measured by radioactive chromium. These data suggest that the erythrocytes of subjects with moderate and severe alcoholic liver cirrhosis are less protected against oxidant stress. The particular erythrocyte antioxidant system and serum trace element pattern may play a role in the genesis of hemolytic disorders and of alcoholic hepatic damage.