[Show abstract][Hide abstract]ABSTRACT: Experimental autoimmune encephalomyelitis (EAE) in Lewis rats is characterized by transient paralysis followed by recovery. To evaluate whether transient paralysis in EAE affects bone density, tibiae of EAE rats were morphologically investigated using micro-computed tomography and histology. The parameters of bone health were significantly reduced at the peak stage of EAE rats relative to those of controls (p < 0.05). The reduction of bone density was found to remain unchanged, even in the recovery stage. Collectively, the present data suggest that osteoporosis occurs in paralytic rats with monophasic EAE, possibly through the disuse of hindlimbs and/or autoimmune inflammation.
[Show abstract][Hide abstract]ABSTRACT: Background: The trabecular bone changes in the tibia of C3H/HeN mice were measured 12 weeks atier whole body irradiation with various doses of fast neutrons (0-2.4 Gy) or 137Cs-generated gamma-rays (0-6 Gy). Materials and Methods: Serum calcium, phosphorus, estradiol concentration and alkaline phosphatase activity were measured. Tibiae were analyzed using microcomputed tomography. Biomechanical property and osteoclast surface level were measured. Results: There was a significant relationship between the loss of bone architecture and the radiation dose, and the best-fi0ng dose -response curves were linear-quadratic. Mean relative biological effectiveness (RBE) values (Ref. gamma) of 2.05 and 2.33 were estimated for fast neutron irradiation in trabecular bone volume fraction and bone mineral density, respectively. There was a substantial reduction in osteoclast surface level in tartrate-resistant acid phosphatase-stained histological sections of tibial metaphyses in irradiated mice with high dose of neutrons. Conclusion: There was a significant relationship between the loss of bone architecture and the radiation dose. The difference of osteoclastic bone resorption may represent a contributor to the low RBE in high dose of irradiation level relative to that of low dose level.
[Show abstract][Hide abstract]ABSTRACT: This in vitro study compared the detrimental effect and relative biological effectiveness (RBE) of high-linear energy transfer (LET) fast neutrons on rat immature hippocampal cultured cells with those of low-LET γ rays. Immature hippocampal cells were exposed to fast neutrons or γ rays. Cytotoxicity and cell viability were analyzed using a lactate dehydrogenase (LDH)-release assay and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, respectively. The cytotoxicity and cell viability with fast neutrons or γ rays varied in a dose-dependent pattern. In the LDH release and MTT assay indices, the RBEs of fast neutrons were approximately 2.35 and 2.42, respectively. Fast neutrons markedly induced apoptotic changes in immature hippocampal cells with increased expression of active caspase-3 and cleaved poly(ADP-ribose) polymerase. Increased cytotoxicity and decreased cell viability in immature hippocampal cells were seen in a dose-dependent pattern after fast-neutron and γ irradiation. Fast neutrons have a higher RBE for cell death indices than γ rays.
Full-text available · Article · Jun 2011 · Radiation Research
[Show abstract][Hide abstract]ABSTRACT: The present study compared the dose–response curves for the frequency of apoptosis in mouse hippocampal dentate gyrus (DG)
and intestinal crypt using whole-body gamma irradiation. The incidence of gamma-ray-induced apoptosis was measured using the
terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end-labelling (TUNEL) method. TUNEL-positive apoptotic nuclei
in the DG and intestinal crypt were increased in a dose-dependent pattern (0–2 Gy). The dose–response curves were linear-quadratic,
with a significant relationship between the appearance of apoptosis and irradiation dose. The slopes of the dose–response
curves in the DG were much steeper (∼5–6-fold) than those in the intestinal crypt within the range of 0–1 Gy exposure. Hippocampal
DG might be a more effective and sensitive evaluation structure than the intestinal crypt to estimate the degree of radiation
exposure in damaged organs of adult mice exposed to low irradiation dose.