Three Measures of Tobacco Dependence Independently Predict Changes in Neural Structure

Studies have demonstrated moderate correlations between fractional anisotropy (FA, a measure of white matter organization), and Fagerström Test for Nicotine Dependence (FTND) scores in various white matter brain structures (r=-.52 to -.64). FA increases with smoking in adolescents, but in adult smokers FA declines with the progression of physical dependence. We examined correlations between FA and 3 measures of tobacco dependence: the FTND, Levels of Physical Dependence (PD), and the Hooked on Nicotine Checklist (HONC). The latter 2 measures assess only symptoms rather than behaviors, based on an assumption that a direct assessment of subjective symptoms will better reflect underlying biological conditions than behaviors that might be constrained by sociocultural factors.We compared white matter FA in 8 smokers and 10 nonsmokers and plotted the location of maximal correlation between FA and each dependence measure. FA trended higher in smokers than nonsmokers in the anterior cingulum bundle (ACb) (p=0.05). Among smokers, plots of the maximal correlation for all 3 measures fell within a circumscribed area of the left ACb, showing excellent concordance of results across measures. The maximal correlation with FA was r= -.78 for the FTND, -.85 for Levels of PD, and -.96 for the HONC (

Progressive levels of physical dependence to tobacco coincide with changes in the anterior cingulum bundle microstructure

BACKGROUND: The tobacco withdrawal syndrome indicates the development of neurophysiologic dependence. Clinical evidence indicates that neurophysiologic dependence develops through a set sequence of symptom presentation that can be assessed with a new 3-item survey measure of wanting, craving, and needing tobacco, the Level of Physical Dependence (PD). This study sought to determine if advancing neurophysiologic dependence as measured by the Level of PD correlates with characteristics of white matter structure measured by Fractional Anisotropy (FA). METHODS: Diffusion-MRI based FA and diffusion tensor imaging probabilistic tractography were used to evaluate 11 smokers and 10 nonsmokers. FA was also examined in relation to two additional measures of dependence severity, the Hooked on Nicotine Checklist (HONC), and the Fagerstrom Test for Nicotine Dependence (FTND). RESULTS: Among smokers, FA in the left anterior cingulate bundle (ACb) correlated negatively with the Level of PD (r = -0.68, p = 0.02) and HONC scores (r = -0.65, p = 0.03), but the correlation for the FTND did not reach statistical significance (r = -49, p = 0.12). With advancing Levels of PD, the density of streamlines between the ACb and precuneus increased (r = -0.67, p\u3c0.05) and those between the ACb and white matter projecting to the superior-frontal cortex (r = -0.86, p = 0.0006) decreased significantly. CONCLUSIONS: The correlations between neural structure and both the clinical Level of PD survey measure and the HONC suggest that the Level of PD and the HONC may reflect the microstructural integrity of white matter, as influenced by tobacco abuse. Given that the Level of PD is measuring a sequence of symptoms of neurophysiologic dependence that develops over time, the correlation between the Level of PD and neural structure suggests that these features might represent neuroplastic changes that develop over time to support the development of neurophysiologic dependence

The development and expression of physical nicotine dependence corresponds to structural and functional alterations in the anterior cingulate-precuneus pathway

INTRODUCTION: Perturbations in neural function provoked by a drug are thought to induce neural adaptations, which, in the absence of the drug, give rise to withdrawal symptoms. Previously published structural data from this study indicated that the progressive development of physical dependence is associated with increasing density of white matter tracts between the anterior cingulum bundle and the precuneus. METHODS: Using functional magnetic resonance imaging, we compared 11 smokers after 11 h of abstinence from nicotine and after satiation, with 10 nonsmoking controls, using independent component analysis for brain network comparisons as well as a whole brain resting-state functional connectivity analysis using the anterior cingulate cortex as a seed. RESULTS: Independent component analysis demonstrated increased functional connectivity in brain networks such as the default mode network associated with the withdrawal state in multiple brain regions. In seed-based analysis, smokers in the withdrawal state showed stronger functional connectivity than nonsmoking controls between the anterior cingulate cortex and the precuneus, caudate, putamen, and frontal cortex (P \u3c 0.05). Among smokers, compared to the satiated state, nicotine withdrawal was associated with increased connectivity between the anterior cingulate cortex and the precuneus, insula, orbital frontal gyrus, superior frontal gyrus, posterior cingulate cortex, superior temporal, and inferior temporal lobe (P \u3c 0.02). The intensity of withdrawal-induced craving correlated with the strength of connectivity between the anterior cingulate cortex and the precuneus, insula, caudate, putamen, middle cingulate gyrus, and precentral gyrus (r = 0.60-0.76; P \u3c 0.05). CONCLUSIONS: In concordance with our previous report that structural neural connectivity between the anterior cingulate area and the precuneus increased in proportion to the progression of physical dependence, resting-state functional connectivity in this pathway increases during nicotine withdrawal in correlation with the intensity of withdrawal-induced craving. These findings suggest that smoking triggers structural and functional neural adaptations in the brain that support withdrawal-induced craving

Variational Principles for Stellar Structure

The four equations of stellar structure are reformulated as two alternate pairs of variational principles. Different thermodynamic representations lead to the same hydromechanical equations, but the thermal equations require, not the entropy, but the temperature as the thermal field variable. Our treatment emphasizes the hydrostatic energy and the entropy production rate of luminosity produced and transported. The conceptual and calculational advantages of integral over differential formulations of stellar structure are discussed along with the difficulties in describing stellar chemical evolution by variational principles.Comment: 28 pages, LaTeX, requires AASTeX, 1 PostScript figure, revisions: erratum; accepted by Astrophysical Journa

Climate change promotes parasitism in a coral symbiosis.

Coastal oceans are increasingly eutrophic, warm and acidic through the addition of anthropogenic nitrogen and carbon, respectively. Among the most sensitive taxa to these changes are scleractinian corals, which engineer the most biodiverse ecosystems on Earth. Corals' sensitivity is a consequence of their evolutionary investment in symbiosis with the dinoflagellate alga, Symbiodinium. Together, the coral holobiont has dominated oligotrophic tropical marine habitats. However, warming destabilizes this association and reduces coral fitness. It has been theorized that, when reefs become warm and eutrophic, mutualistic Symbiodinium sequester more resources for their own growth, thus parasitizing their hosts of nutrition. Here, we tested the hypothesis that sub-bleaching temperature and excess nitrogen promotes symbiont parasitism by measuring respiration (costs) and the assimilation and translocation of both carbon (energy) and nitrogen (growth; both benefits) within Orbicella faveolata hosting one of two Symbiodinium phylotypes using a dual stable isotope tracer incubation at ambient (26 °C) and sub-bleaching (31 °C) temperatures under elevated nitrate. Warming to 31 °C reduced holobiont net primary productivity (NPP) by 60% due to increased respiration which decreased host %carbon by 15% with no apparent cost to the symbiont. Concurrently, Symbiodinium carbon and nitrogen assimilation increased by 14 and 32%, respectively while increasing their mitotic index by 15%, whereas hosts did not gain a proportional increase in translocated photosynthates. We conclude that the disparity in benefits and costs to both partners is evidence of symbiont parasitism in the coral symbiosis and has major implications for the resilience of coral reefs under threat of global change

Influence of conjugated linoleic acid (CLA) or tetradecylthioacetic acid (TTA) on growth, lipid composition, fatty acid metabolism and lipid gene expression of rainbow trout (Oncorhynchus mykiss L.)

Our objective was to test the hypotheses that conjugated linoleic acid (CLA) and/or tetradecylthioacetic acid (TTA) would have beneficial effects on the nutritional quality of rainbow trout (Oncorhynchus mykiss) through decreased lipid content of flesh or viscera, and increased levels of beneficial fatty acids including accumulation of CLA or TTA themselves. The specific aims of this study were to determine the effects of CLA and TTA on growth performance, lipid and fatty acid metabolism, and selected gene expression in commercial sized trout grown in seawater. Trout were fed for eight weeks on fish meal and fish oil diets containing either 0.5% or 1% CLA, or 0.5% TTA. The effects of the supplemented fatty acids on growth, feed efficiency, lipid contents, class compositions and fatty acid compositions of flesh and liver were determined, along with liver highly unsaturated fatty acid synthesis, activities of key enzymes of fatty acid oxidation in liver and muscle, and expression of carnitine palmitoyltransferase-I (CPT-I) and fatty acyl desaturase and elongase genes. Neither functional fatty acid had any effect on growth parameters, condition factor, viscero- and hepato-somatic indices or fillet colour, and there were no mortalities in any of the treatments. Dietary CLA, but not TTA, decreased the lipid content of liver, but neither fatty acid had any significant effect on lipid class compositions of liver and flesh. Both CLA and TTA were incorporated into tissue lipids, with higher percentages found in flesh compared to liver. In addition, production of hexaene fatty acid by liver microsomes was increased by dietary CLA or TTA, and both functional fatty acids increased the proportion of n-3 fatty acids in liver mainly due to increased 20:5n-3 and 22:6n-3. However, the expression of fatty acyl Δ6 desaturase was significantly lower in fish fed CLA or TTA, whereas the expression of PUFA elongase was increased, significantly so in fish fed 1% CLA. CPT-I activity was increased by TTA in liver and red muscle, and acyl CoA oxidase activity was increased by TTA in liver and CLA at the higher dietary inclusion level in red muscle. There was a clear trend for CPT-I expression to be increased in fish fed 0.5% CLA or TTA in all tissues although this was only significant in white muscle. The results showed that both CLA and TTA had effects on lipid metabolism that partly support the hypotheses tested. Although CLA or TTA did not enhance growth parameters, feed conversion or potential yield, nutritional quality could be enhanced, and sea-run trout fed CLA or TTA could be beneficial in the human diet through provision of bioactive fatty acids, with no detrimental effects on 20:5n-3 or 22:6n-3 levels

Influence of dietary conjugated linoleic acid (CLA) and tetradecylthioacetic acid (TTA) on growth, lipid composition and key enzymes of fatty acid oxidation in liver and muscle of Atlantic cod (Gadus morhua L.)

The aim of the present study was to determine the effects of conjugated linoleic acid (CLA) and tetradecylthioacetic acid (TTA) on growth performance, and lipid and fatty acid metabolism in Atlantic cod. The overall objective being to test the hypotheses that CLA and TTA have beneficial effects in cod culture including decreased liver size and proportion through decreased lipid content, and increased nutritional quality through effects on fatty acid compositions including accumulation of bioactive fatty acids, CLA and TTA, in flesh. Juvenile cod were fed for three months on fish meal and fish oil diets of basically commercial formulation, but containing either 0.5% or 1% CLA, or 0.5% TTA. The effects of the functional fatty acids on growth, feed efficiency, body proximate composition, liver weight and lipid composition, fatty acid compositions of flesh and liver, and key enzymes of fatty acid oxidation were determined. Dietary CLA and TTA had no effect on growth parameters in cod juveniles, but viscero- and hepato-somatic indices were increased in fish fed 0.5% CLA and TTA, respectively. Proximate composition of whole fish was not affected by CLA or TTA, and there were no major effects of either functional fatty acid on lipid contents and compositions of liver and flesh. Dietary CLA and TTA were both incorporated into tissue lipids, with CLA deposited to a greater extent in liver, whereas TTA was deposited to a greater extent in flesh. In liver, acyl CoA oxidase (ACO) activity, but not carnitine palmitoyltransferase-I (CPT-I), was increased by CLA, whereas dietary TTA increased both ACO and CPT-I activities. In contrast, ACO activity was reduced by both CLA and TTA in red and white muscle, whereas CPT-I activity was generally not affected by CLA and TTA in either muscle tissue. Therefore, the results only partially supported the hypotheses tested, as CLA and TTA had few beneficial effects in Atlantic cod and did not enhance growth parameters, or improve feed conversion or potential yield through decreased adiposity or liver lipid deposition. However, nutritional quality could be enhanced, and cod fed CLA and/or TTA could be beneficial in the human diet, through provision of bioactive fatty acids with no detrimental effects on n-3 PUFA levels

Mighty Eagle Lander Testbed

No abstract availabl

On effective actions of non-BPS branes and their higher derivative corrections

By calculating various disk level S-matrix elements and studying in details their momentum expansions, we have extracted some of the couplings in tachyon DBI action and Wess-Zumino terms of the non-BPS branes, and their higher derivative corrections. In particular, we have found that there is exact consistency between field theory and string theory tachyon pole of S-matrix element of one RR and three tachyons provided that one takes into account the fact that the tachyon vertex operator in 0 picture to be along the Pauli matrix $\sigma_1$ whereas the tachyon in -1 picture to be along the $\sigma_2$ direction. This internal CP factors should be included in the tachyon DBI part of the effective action.Comment: 26 pages, latex file; V5: a missing term in the modified tachyon DBI action adde