Induction of apoptosis by beta radiation from tritium compounds in mouse embryonic brain cells

Assessment of lymphocyte proliferation for diagnostic purpose: Comparison of CFSE staining, Ki-67 expression and 3H-thymidine incorporation

The capability of lymphocytes to respond to antigenic or mitogenic stimulation is an important feature in the diagnosis of various immunodeficiencies and immune disorders. We used large cohorts of both immune compromised patients and healthy controls to measure lymphocyte proliferations by means of three methods: CFSE staining, Ki-67 expression and ³H-thymidine incorporation. The advantages and disadvantages of each method was then evaluated for use in routine clinical diagnostic. The statistical analysis was performed between the outcomes and the correlation between all three methods was computed. CFSE and Ki-67 assay correlated well with the r=0.767, correlation between Ki-67 expression and ³H-thymidine incorporation was 0.546 and correlation between CFSE staining and ³H-thymidine incorporation was 0.337. The differences between these three methods concerning complexity, sensitivity and reliability as well as the financial aspects are discussed hereafter. CFSE and its analogues provide the cheapest and reasonable choice for measuring lymphocyte proliferation, while Ki-67 represents a more expensive, but more sensitive and robust method. The original ³H-thymidine assay does not bring any advantages and cannot compare to the competition presented by modern flow cytometric methods available today.

Dragon's blood may have radioprotective effects in radiation-induced rat brain injury

Dragon's blood is a bright red resin obtained from Dracaena cochinchinensis. It is a traditional medicinal that is used for wound healing and to stop bleeding. Its main biological activity appears to be from phenolic compounds found in Dragon's blood. In this study, the radioprotective effects of Dragon's blood were examined after whole brain irradiation of rats with either 100 MeV/u Carbon (12)C(6+) heavy ions or (60)Co γ-rays. The amounts of radiation-induced oxidative stress, inflammatory cytokines and apoptosis in irradiated rat brains were compared with and without Dragon's blood treatment. Compared to the "irradiation only" control group, the Dragon's blood treatment group significantly decreased malondialdehyde and hydrogen peroxide levels, and increased superoxide dismutase activity and glutathione levels induced by oxidative stress in radiation exposed rats (P < 0.05). Dragon's blood also significantly reduced radiation-induced inflammatory cytokines of tumor necrosis factor-α, interferon-γ and interleukin-6 levels (P < 0.05) and inhibited hippocampal neuronal apoptosis in (60)Co γ-ray irradiated rats. Furthermore, Dragon's blood significantly increased expression of brain-derived neurophic factor and inhibited the expression of pro-apoptotic caspase 3 (P < 0.05-0.01). Finally, Dragon's blood significantly inhibited expression of the AP-1 transcription factor family members c-fos and c-jun proteins (P < 0.05-0.01). The results obtained here suggest that Dragon's blood has radioprotective properties in rat brains after both heavy ions and (60)Co γ-ray exposure.

Prenatal protracted irradiation at very low dose rate induces severe neuronal loss in rat hippocampus and cerebellum

Prenatal irradiation is known to damage the developing brain. However, little is known about the consequences of very low dose rate prenatal protracted irradiation over several days on neuron numbers in the offspring brain, and on volumes of the corresponding brain regions. Pregnant Wistar rats were exposed either to a protracted gamma irradiation from embryonic day (E) 13 to E16 (0.7 mGy/min; total cumulative dose approximately 3 Gy) or were sham-irradiated. Thirty months old male and female offspring were then analyzed for alterations in hippocampal and cerebellar morphology. Using design-based stereology and the analysis of sets of sections systematically and randomly sampled to span the entire brain region of interest, a statistically significant decrease in numbers of hippocampal pyramidal and granule cells as well as of cerebellar Purkinje and granule cells (approximately 50%) was found in male and female irradiated offspring. The volumes of these brain regions were comparably altered. The analysis of only a "representative" section per animal yielded mostly non-significant trends. Evaluation of neuron densities showed no differences between prenatally irradiated and sham-irradiated offspring. Most importantly, very low dose rate prenatal protracted gamma irradiation did not result in the same morphologic alterations in the offspring brain as previously observed after prenatal single irradiation such as derangement of the laminar structure of pyramidal cells within the hippocampus or malformation of cerebellar lobules.

Beta irradiation decreases collagen type II synthesis and increases nitric oxide production and cell death in articular chondrocytes

BACKGROUND

When synovitis is proved, intra-articularly injected beta emitting radionuclides like yttrium-90 ((90)Y) are used to treat the inflamed synovium.

OBJECTIVE

To study the viability, matrix production, and NO production during or after (90)Y treatment of chondrocytes.

METHODS

Monolayer, alginate, and explant cultures of primary bovine articular chondrocytes as well as synoviocytes were incubated with 0-3 MBq (90)Y/ml medium for four days from culture day 3 onwards. Cell viability was demonstrated by light and electron microscopy or by trypan blue or ethidium bromide/fluorescein diacetate staining, membrane integrity by measurement of lactate dehydrogenase (LDH) activity in the culture supernatants. Biosynthetic activity was demonstrated by incorporation of [(3)H]proline and immunocytochemical staining of collagen type II. NO production was measured with the Griess reagent.

RESULTS

In chondrocyte and synoviocyte monolayer cultures radiation caused a dose dependent increase in cell death and membrane destruction within four days. In alginate and explant cultures, where proliferation is low, no significantly increased LDH activity was seen, and cell viability was approximately 100% for up to 14 days after irradiation. Collagen type II expression (alginate) and biosynthetic activity (alginate and explants) were decreased dose dependently while there was an increase in NO production. Light and electron microscopy data showed that five weeks after irradiation all cells in alginate and most cells in explants subjected to 3 MBq (90)Y/ml were dead, whereas after lower amounts of irradiation several morphologically intact cells were found.

CONCLUSIONS

beta Irradiation may influence the long term maintenance of cartilage tissue or the aetiology of degenerative joint diseases.

3H-thymidine is a defective tool with which to measure rates of DNA synthesis

Metabolic incorporation of 3H-thymidine into cellular DNA is a widely used protocol to monitor rates of DNA synthesis and cell proliferation. However, this radiochemical has also been reported to induce cell-cycle arrest and apoptosis in addition to DNA damage. Using stable isotope-labeled thymidine, we demonstrate that 3H-thymidine induces dose-dependent inhibition of the rate of DNA synthesis. This inhibition occurred within the first round of replication after addition of the radiolabeled tracer and demonstrates the cytotoxic effects of conventional doses of 3H-thymidine (typically greater than or equal to 1 microCi/ml). These results thus show that stable isotope methods are superior to radioisotopes for determining rates of DNA synthesis and cell replication. Because 3H-thymidine perturbs the very process it was employed to study, experiments using 3H-thymidine to monitor DNA synthesis and cell proliferation should be interpreted with caution.

Postnatal growth, neurobehavioral and neurophysiologic changes of prenatal low-dose beta-radiation from tritiated water in mice

Pregnant adult C57BL/6J mice were randomly assigned to four groups: one sham and three irradiated groups that were exposed to -irradiation from tritiated water (HTO) by a single intraperitoneal injection on Day 12.5 of gestation. The offspring received cumulative doses of 0.036, 0.071, and 0.213 Gy, respectively. The litters were observed for postnatal growth (body weight, brain weight), the development of four physiologic milestones (pinna detachment, eye opening, testes decent, vaginal opening), the acquisition age of several reflexes (cliff avoidance, air righting) and sensory functions (auditory startle, thermal reflex), movement and coordination functions and activity (pivoting, foot splay, continuous corridor activity), learning and memory performance (shock avoidance, conditioning reflex), and the density of CA1-CA4 hippocampal pyramidal neurons. Modest but significant dose-dependent neuronal death and functional impairment were seen in both 0.071 and 0.213 Gy groups. In conclusion, even prenatal low-dose beta-radiation may impair murine central nervous system (CNS) development suggesting the potential importance of minimizing environmental exposure during human pregnancy.