Animal mortality

About: Animal mortality is a research topic. Over the lifetime, 526 publications have been published within this topic receiving 14887 citations.

Muskox Bull Killed by a Barren-Ground Grizzly Bear, Thelon Game Sanctuary, N. W. T.

Abstract: The carcass of an adult muskox bull ( Ovibos moschatus ) killed by a barren-ground grizzly bear ( Ursus arctos richardsoni ) was found in the Thelon Game Sanctuary. It is suggested that adult muskox bulls along the Thelon River system have become prey for at least some grizzly bears that have learned to ambush them in dense vegetation. Key words: muskoxen ( Ovibos moschatus ); grizzly bear ( Ursus arctos richardsoni ); predation

Protective effects of hydrogen‑rich saline against experimental diabetic peripheral neuropathy via activation of the mitochondrial ATP‑sensitive potassium channel channels in rats.

Abstract: It has previously been demonstrated that hyperglycemia-induced oxidative stress and inflammation are closely associated with the development of diabetic complications, including diabetic neuropathy. Additionally, mitochondrial ATP-sensitive potassium (Mito-K-ATP) channels play a homeostatic role on blood glucose regulation in organisms. Molecular hydrogen (H2) exhibits anti-inflammatory, anti-antioxidative and anti-apoptotic properties and can be used to treat more than 71 diseases safely. In addition, the diabetes animal models which are set up using streptozotocin (STZ) injection, is a type of high long-term stability, low animal mortality rate and security method. The aim of the current study was to assess the value of hydrogen-rich saline (HS) in diabetic peripheral neuropathy (DPN) treatment and to determine its associated mechanisms in STZ-induced diabetic experimental rats. Additionally, the effects of the Mito-K-ATP channels, oxidative stress, inflammatory cytokines and apoptosis on DPN were also evaluated. From week 5 of STZ injections, HS (2.5, 5 and 10 ml/kg) was injected into the rat abdominal cavity every day for a period of 4 weeks. The results of the current study demonstrated that HS significantly reduced behavioral, biochemical and molecular effects caused by DPN. However, 5-hydroxydecanoate, a selective Mito-K-ATP channels general pathway inhibitor, partially eliminated the therapeutic effect of HS on DPN. These results indicated that the use of HS may be a novel strategy to treat DPN by activating the Mito-K-ATP pathway and reducing oxidative stress, inflammatory cytokines and apoptosis.

The molecular basis of stochastic and nonstochastic effects.

Abstract: Stochastic effects have been defined as those for which the probability increases with dose, without a threshold. Nonstochastic effects are those for which incidence and severity depends on dose, but for which there is a threshold dose. These definitions suggest that the two types of effects are not related. In this paper it will be shown that at least some of the nonstochastic effects are the consequence of accumulated stochastic effects and that both types of effect can be related to a common cellular damage. It is proposed that, at the cellular level, effects such as mutation induction and cell reproductive death are related to DNA double-strand breaks caused by radiation. Further, we propose that stochastic effects depend on a mutational event induced in a critical cell of a target organ. Nonstochastic effects are considered to arise because the function of a substantial proportion of critical cells is impaired. In some cases the predominant effect is comparable to cell reproductive death. Animal mortality, for instance, may occur because a substantial proportion of bone marrow cells is killed. Using this concept, mathematical formulas can be derived for the various effects. Modification of the irradiation conditions (e.g., low dose rate or density ionizing radiation) leads to changes in the initial molecular lesions and, consequently, to changes in the dose effect relationships of stochastic and nonstochastic effects. Experimental support will be discussed, using animal mortality as an endpoint. The implications of this approach will be discussed with emphasis on its application to radiological protection.

Circulating IL-18 Binding Protein (IL-18BP) and IL-18 as Dual Biomarkers of Total-Body Irradiation in Mice

Abstract: We have previously reported that circulating interleukin-18 (IL-18) can be used as a radiation biomarker in mice, minipigs and nonhuman primates. In this study, we further determined the serum levels of IL-18 binding protein (IL-18BP), a natural endogenous antagonist of IL-18, in CD2F1 mice 1-13 days after total-body gamma irradiation (TBI) with different doses (5-10 Gy). We compared the changes in blood lymphocyte, neutrophil and platelet counts as well as the activation of the proapoptotic executioner caspase-3 and caspase-7, and the expression of the inflammatory factor cyclooxygenase 2 (COX-2) in spleen cells, with the changes of IL-18BP and IL-18 in mouse serum. We also evaluated the significance, sensitivity and specificity of alterations in radiation-induced IL-18BP. IL-18 increased from day 1-13 after TBI in a dose-dependent manner that was paralleled with an increase in IL-18 receptor alpha (IL-18Rα) in irradiated mouse spleen cells. IL-18BP rapidly increased (25-63 fold) in mouse serum on day 1 after different doses of TBI. However, it returned to baseline within 3 days after 5-7 Gy doses and within 7 days after 8 Gy dose, and was unaltered thereafter. In contrast, high doses of radiation (9 and 10 Gy) significantly sustained a higher level of IL-18BP in mouse serum and later induced a second phase of increase in IL-18BP on day 9-13 after irradiation, which coincided with the onset of animal mortality. Consistent with this observation, highly activated caspase-3 and -7 in 8-10 Gy irradiated mouse spleen cells exhibited reduced or no activity 24 h after 5 Gy, although radiation induced an inflammatory response, as shown by COX-2 expression in all irradiated cells. Our data suggest that the radiation-induced differential elevation of IL-18 and IL-18BP in animal serum is a dynamic and discriminative indicator of the severity of injury after exposure to ionizing radiation. These findings support the inclusion of the dual biomarkers IL-18BP and IL-18 in the development of a multifactorial strategy for radiation dose and injury assessment.

Circadian rhythm and 5-fluorouracil toxicity in C3H mice.

Abstract: In order to study the effect of daily (circadian) rhythm on toxicity of an anticancer drug, 5-fluorouracil, adult female C3H mice were used in this work. A dose of 200 mg/kg of 5-FU was administered intraperitoneally to the animals. Body weights and animal mortality were observed daily during the following 21 days after administration of the drug. The most severe toxic effect of 5-FU, with 100% mortality, was observed when the drug was administered at 4 am, whereas at 12 am 5-FU was least toxic. Since C3H mice are nocturnal animals, they are at the peak activity in the early morning hours of the day. Thus, it seems that an increased 5-FU toxicity in C3H mice coincides with an increased metabolic rate and other physiological processes of these nocturnal animals.