The other two hypotheses invoke stronger constraints. The state selection hypothesis states that when a system can attain multiple
steady states, the stable state will show the highest entropy production rate. The gradient response principle requires that when the thermodynamic gradient increases, the system’s new stable state should always be accompanied by a higher entropy production rate. We test these three hypotheses by Stem Cell Compound Library applying them to a set of conventional food web models. Each time, we calculate the entropy production rate associated with the stable state of the ecosystem. This analysis shows that the first hypothesis holds for all the food webs tested: the living state shows always an increased entropy production over the abiotic state. In contrast, the state selection and gradient response hypotheses break down when the food web incorporates more than one trophic level, indicating that they are not generally valid.”
“Background: Accumulating evidence suggests that the occurrence of oxidative stress leads to melanocyte degeneration
in vitiligo. Elevated level of dopamine (DA), an initiator of oxidative stress, reportedly is found in patients with vitiligo and induces melanocyte death in vitro. DA-treated melanocytes have been used CX-6258 supplier as a model to search for antioxidants for treating vitiligo.
Objective: We investigated the protective effects of apigenin against DA-induced apoptosis in melanocytes and the molecular mechanism underlying those effects.
Methods: Melanocytes with or without pretreatment with apigenin were exposed to DA. Then cell viabilities were measured by MTT assay. Cellular reactive oxygen species (ROS) levels and the percentage of apoptotic cells were detected by flow cytometry analysis. Activation of caspase 3, poly(ADP-ribose) polymerase (PARP) and oxidative stress-related signaling, including p38, c-Jun NH2-terminal kinase (JNK) and Akt, were assessed by Western blotting.
Results: Apigenin attenuated DA-induced apoptotic cell death, relieved ROS accumulation and activated caspase 3 and PARP, suggesting the protective effects of apigenin against DA-induced oxidative stress and selleck products apoptosis in melanocytes.
Moreover, DA induced phosphorylation of p38, JNK and Akt, while inhibitors of p38, JNK and Akt significantly decreased DA-induced apoptosis. However, pretreatment with apigenin significantly inhibited DA-triggered activation of p38, JNK and Akt, suggesting the involvement of p38, JNK and Akt in the protective effects of apigenin against DA-induced cytotoxicity.
Conclusion: These results suggest that apigenin attenuates dopamine-induced apoptosis in melanocytes via oxidative stress-related p38. JNK and Akt signaling and therefore could be a potential agent in treating vitiligo. (C) 2011 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.”
“Alcohol abuse in the adult is often preceded by high alcohol consumption during adolescence.