The triplet state photophysics of phenanthrene

The first excited triplet state (TI state) of aromatic hydrocarbons such as phenanthrene acts as an intermediate in many chemical and photochemical reactions. The TI state is a metastable state and its lifetime can be measured in terms of its decay to the ground state. The duration of this decay is on the order of microseconds. Therefore, techniques for measuring the kinetics of fast reactions must be employed in the determination of the rate of the TI state decay, one such technique that is utilized in this research is flash photolysis. The rate of the Tl state decay is greatly enhanced by the presence of oxygen. Therefore, to accurately measure the first order Tl state decay, the phenanthrene solution must be degassed prior to flashing in order to remove dissolved oxygen. A vacuum line is designed for this purpose. Based on the experimental data, it was determined that scattered flash light must be eliminated from the flash apparatus and that the vacuum line must be redesigned for more efficient degassing

Hoofprints in the sand:A study on domestic sheep (Ovis aries) from Iron Age southern Phoenicia using traditional biometric methods

The majority of research to date on the translocation of livestock in the premodern (before 1500 CE) Mediterranean Basin has focused on expansive movements out from geographic origins of domestication or from colonizer-to-colonized territories. Fewer zooarchaeological studies have investigated the lateral trajectories of distinct varieties of domesticated animals around the post-Neolithic eastern Mediterranean, partially due to the difficulty in detecting intra-species variation osteologically. The research conducted in the present study sought to improve understanding of the human-mediated mobility of domestic sheep (Ovis aries) from Iron Age settlements in the southern Levant. Variability in body size and a greater variety of morphotypes were expected from coastal flocks in southern Phoenicia in comparison to inland herds, possibly due to the dynamic influence of maritime trade. Biometric data analysis of zooarchaeological materials using log size index and astragalar dimension index methods revealed evidence for the possible optimization of coastal sheep for wool production and a potential introduction event in the Persian period. The Aegean region could be a source for this introduction; however, further research is needed to specify the geographic origin of this phenomenon.</p

Mitochondrial redox studies of oxidative stress in kidneys from diabetic mice

Chronic hyperglycemia during diabetes leads to increased production of reactive oxygen species (ROS) and increased oxidative stress (OS). Here we investigated whether changes in the metabolic state can be used as a marker of OS progression in kidneys. We examined redox states of kidneys from diabetic mice, Akita/+ and Akita/+;TSP1–/– mice (Akita mice lacking thrombospondin-1, TSP1) with increasing duration of diabetes. OS as measured by mitochondrial redox ratio (NADH/FAD) was detectable shortly after the onset of diabetes and further increased with the duration of diabetes. Thus, cryo fluorescence redox imaging was used as a quantitative marker of OS progression in kidneys from diabetic mice and demonstrated that alterations in the oxidative state of kidneys occur during the early stages of diabetes

Defining the tipping point. A complex cellular life/death balance in corals in response to stress

Apoptotic cell death has been implicated in coral bleaching but the molecules involved and the mechanisms by which apoptosis is regulated are only now being identified. In contrast the mechanisms underlying apoptosis in higher animals are relatively well understood. To better understand the response of corals to thermal stress, the expression of coral homologs of six key regulators of apoptosis was studied in Acropora aspera under conditions simulating those of a mass bleaching event. Significant changes in expression were detected between the daily minimum and maximum temperatures. Maximum daily temperatures from as low as 3°C below the bleaching threshold resulted in significant changes in both pro- and anti-apoptotic gene expression. The results suggest that the control of apoptosis is highly complex in this eukaryote-eukaryote endosymbiosis and that apoptotic cell death cascades potentially play key roles tipping the cellular life/death balance during environmental stress prior to the onset of coral bleaching

Regulation of Apoptotic Pathways by Stylophora pistillata (Anthozoa, Pocilloporidae) to Survive Thermal Stress and Bleaching

Elevated seawater temperatures are associated with coral bleaching events and related mortality. Nevertheless, some coral species are able to survive bleaching and recover. The apoptotic responses associated to this ability were studied over 3 years in the coral Stylophora pistillata from the Gulf of Eilat subjected to long term thermal stress. These include caspase activity and the expression profiles of the S. pistillata caspase and Bcl-2 genes (StyCasp and StyBcl-2-like) cloned in this study. In corals exposed to thermal stress (32 or 34°C), caspase activity and the expression levels of the StyBcl-2-like gene increased over time (6–48 h) and declined to basal levels within 72 h of thermal stress. Distinct transcript levels were obtained for the StyCasp gene, with stimulated expression from 6 to 48 h of 34°C thermal stress, coinciding with the onset of bleaching. Increased cell death was detected in situ only between 6 to 48 h of stress and was limited to the gastroderm. The bleached corals survived up to one month at 32°C, and recovered back symbionts when placed at 24°C. These results point to a two-stage response in corals that withstand thermal stress: (i) the onset of apoptosis, accompanied by rapid activation of anti-oxidant/anti-apoptotic mediators that block the progression of apoptosis to other cells and (ii) acclimatization of the coral to the chronic thermal stress alongside the completion of symbiosis breakdown. Accordingly, the coral's ability to rapidly curb apoptosis appears to be the most important trait affecting the coral's thermotolerance and survival

Transglutaminase 2 at the Crossroads between Cell Death and Survival

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A multiscale systems perspective on cancer, immunotherapy, and Interleukin-12

Monoclonal antibodies represent some of the most promising molecular targeted immunotherapies. However, understanding mechanisms by which tumors evade elimination by the immune system of the host presents a significant challenge for developing effective cancer immunotherapies. The interaction of cancer cells with the host is a complex process that is distributed across a variety of time and length scales. The time scales range from the dynamics of protein refolding (i.e., microseconds) to the dynamics of disease progression (i.e., years). The length scales span the farthest reaches of the human body (i.e., meters) down to the range of molecular interactions (i.e., nanometers). Limited ranges of time and length scales are used experimentally to observe and quantify changes in physiology due to cancer. Translating knowledge obtained from the limited scales observed experimentally to predict patient response is an essential prerequisite for the rational design of cancer immunotherapies that improve clinical outcomes. In studying multiscale systems, engineers use systems analysis and design to identify important components in a complex system and to test conceptual understanding of the integrated system behavior using simulation. The objective of this review is to summarize interactions between the tumor and cell-mediated immunity from a multiscale perspective. Interleukin-12 and its role in coordinating antibody-dependent cell-mediated cytotoxicity is used illustrate the different time and length scale that underpin cancer immunoediting. An underlying theme in this review is the potential role that simulation can play in translating knowledge across scales