Inhibiting food reward: delay discounting, food reward sensitivity, and palatable food intake in overweight and obese women

Overeating is believed to result when the appetitive motivation to consume palatable food exceeds an individual's capacity for inhibitory control of eating. This hypothesis was supported in recent studies involving predominantly normal weight women, but has not been tested in obese populations. The current study tested the interaction between food reward sensitivity and inhibitory control in predicting palatable food intake among energy-replete overweight and obese women (N = 62). Sensitivity to palatable food reward was measured with the Power of Food Scale. Inhibitory control was assessed with a computerized choice task that captures the tendency to discount large delayed rewards relative to smaller immediate rewards. Participants completed an eating in the absence of hunger protocol in which homeostatic energy needs were eliminated with a bland preload of plain oatmeal, followed by a bogus laboratory taste test of palatable and bland snacks. The interaction between food reward sensitivity and inhibitory control was a significant predictor of palatable food intake in regression analyses controlling for BMI and the amount of preload consumed. Probing this interaction indicated that higher food reward sensitivity predicted greater palatable food intake at low levels of inhibitory control, but was not associated with intake at high levels of inhibitory control. As expected, no associations were found in a similar regression analysis predicting intake of bland foods. Findings support a neurobehavioral model of eating behavior in which sensitivity to palatable food reward drives overeating only when accompanied by insufficient inhibitory control. Strengthening inhibitory control could enhance weight management programs.     

Large gallanes and the PSEPT theory: a theoretical study of Ga n H n+2 clusters (n?=?7–9)

Do alanes Al(n)H(n+2) and gallanes Ga(n)H(n+2) satisfy the polyhedral skeletal electron pair theory (PSEPT)? Taking into account previous work on this question, this paper provides a convincing answer and proposes the reformulation of the (n + 1) electron pairs rule of Wade and Mingos (W-M) for such systems. Following recent studies of tetra-, penta-, hexa-, hepta-, octa-, and nonaalanes as well as valence-isoelectronic/related gallanes, in this paper we present an analysis of the hydrides of aluminum and gallium A(n)H(n+2) (A = Al, Ga and n = 7-9). The aim is still to examine the applicability of PSEPT, especially the W-M rule, to these clusters. Exploration of the total potential energy surfaces (PESs) of hepta-, octa-, and nonagallanes shows that the absolute minima have a nido-like polyhedron arrangement. Unlike the smaller Ga(n)H(n+2) (n = 4, 5, 6), it seems that the size of the cluster largely dictates its preferred geometry. Although none of them have closed (totally triangular) cages, these clusters exhibit significant compactness, comparable to borane double anions, B(n)H(n) (2-), which are the archetypes for the PSEPT theory.     

The relevance of tissue thiol histochemistry to diagnostic hematopathology

Expression analyses suggest that alterations of the antioxidant state of some diffuse large B-cell lymphomas can assist prognosis; reversibly oxidized thiols may serve as a surrogate marker for identifying such cases. Little is known about the distribution of free thiols and reversibly oxidized thiols in human tissues. We developed a staining technique that enables visualization of tissue thiols in situ using bright field microscopy and validated it using gastrointestinal tissue specimens. We used our thiol staining technique to assess benign tonsillectomy and diffuse large B-cell lymphoma specimens. The gastrointestinal series revealed the presence of free thiols within epithelial cells and cells of the lamina propria. Staining for reversibly oxidized thiols was robust in gastric foveolar cells, intestinal goblet cells and the mucus they produce. Tonsillectomy specimens exhibited diffuse presence of free thiols. Staining for reversibly oxidized thiols was confined to germinal center macrophages and sinus histiocytes. Among the diffuse large B-cell lymphoma specimens, we observed strong staining for free thiols within malignant cells. By contrast to benign B-cells, the malignant cells demonstrated pronounced and diffuse staining for reversibly oxidized thiols. We demonstrated intrinsic differences between benign and malignant cells.     

Ground beetle (Coleoptera: Carabidae) assemblages in conventional and diversified crop rotation systems

Ground beetles (Coleoptera: Carabidae) are important in agro-ecosystems as generalist predators of invertebrate pests and weed seeds and as prey for larger animals. However, it is not well understood how cropping systems affect ground beetles. Over a 2-yr period, carabids were monitored two times per month using pitfall traps in a conventional chemical input, 2-yr, corn/soybean rotation system and a low input, 4-yr, corn/soybean/triticale-alfalfa/alfalfa rotation system. Carabid assemblages were largely dominated by a few species across all cropping treatments with Poecilus chalcites Say comprising >70% of pitfall catches in both years of study. Overall carabid activity density and species richness were higher in the low input, 4-yr rotation compared with the conventionally managed, 2-yr rotation. There were greater differences in the temporal activity density and species richness of carabids among crops than within corn and soybean treatments managed with different agrichemical inputs and soil disturbance regimes. Detrended correspondence analysis showed strong yearly variation in carabid assemblages in all cropping treatments. The increase in carabid activity density and species richness observed in the 4-yr crop rotation highlights the potential benefits of diverse crop habitats for carabids and the possibility for managing natural enemies by manipulating crop rotations.     

The Sup35 domains required for maintenance of weak, strong or undifferentiated yeast [PSI+] prions

The Sup35 protein can exist in a non-infectious form or in various infectious forms called [PSI+] prion variants (or prion strains). Each of the different [PSI+] prion variants converts non-infectious Sup35 molecules into that prion variant's infectious form. One definition of a 'prion domain' is the minimal fragment of a prion protein that is necessary and sufficient to maintain the prion form. We now demonstrate that the Sup35 N region (residues 1-123), which is frequently referred to as the 'prion domain', is insufficient to maintain the weak or strong [PSI+] variants per se, but appears to maintain them in an 'undifferentiated' [PSI+] state that can differentiate into weak or strong [PSI+] variants when transferred to the full-length Sup35 protein. In contrast, Sup35 residues 1-137 are necessary and sufficient to faithfully maintain weak or strong [PSI+] variants. This implicates Sup35 residues 124-137 in the variant-specific maintenance of the weak or strong [PSI+] forms. Structure predictions indicate that the residues in the 124-137 region form an alpha-helix and that the 1-123 region may have beta structure. In view of these findings, we discuss a plausible molecular basis for the [PSI+] prion variants as well as the inherent difficulties in defining a 'prion domain'.     

Destabilizing interactions among [PSI(+)] and [PIN(+)] yeast prion variants

The yeast Sup35 and Rnq1 proteins can exist in either the noninfectious soluble forms, [psi-] or [pin-], respectively, or the multiple infectious amyloid-like forms called [PSI+] or [PIN+] prion variants (or prion strains). It was previously shown that [PSI+] and [PIN+] prions enhance one another's de novo appearance. Here we show that specific prion variants of [PSI+] and [PIN+] disrupt each other's stable inheritance. Acquiring [PSI+] often impedes the inheritance of particular [PIN+] variants. Conversely, the presence of some [PIN+] variants impairs the inheritance of weak [PSI+] but not strong [PSI+] variants. These same [PIN+] variants generate a single-dot fluorescence pattern when a fusion of Rnq1 and green fluorescent protein is expressed. Another [PIN+] variant, which forms a distinctly different multiple-dot fluorescence pattern, does not impair [PSI+] inheritance. Thus, destabilization of prions by heterologous prions depends upon the variants involved. These findings may have implications for understanding interactions among other amyloid-forming proteins, including those associated with certain human diseases.     

Effects of red clover (Trifolium pratense) green manure and compost soil amendments on wild mustard (Brassica kaber) growth and incidence of disease

Using a soil bioassay technique, seedling growth and incidence of disease of wild mustard (Brassica kaber) and sweet corn (Zea mays) were assessed in soil from field plots that received either of two treatments: incorporated red clover (Trifolium pratense) residue plus application of compost (`amended soil'), or application of ammonium nitrate fertilizer (`unamended soil'). Soils were analyzed for percent moisture, dissolved organic carbon, conductivity, phenolics, and nutrient content. A trend toward greater incidence of Pythium spp. infection of wild mustard seedlings grown in amended soil was observed during the first 40 days after incorporation (DAI) of red clover and compost, with significant differences ( = 0.05) at two out of four sampling dates in 1997, and four out of four sampling dates in 1998. Incidence of Pythium infection was 10–70% greater in the amended soil treatment during that period. Asymptomatic wild mustard seedlings grown in amended soil were also on average 2.5 cm shorter ( = 0.05) at 5 DAI than those grown in unamended soil in one year out of two. Concentration of phenolic compounds in soil solution was weakly correlated with decreased shoot and root growth (r = 0.50, 0.28, respectively) and increased incidence of disease (r = 0.48) in wild mustard seedlings in one year out of two. Dissolved organic carbon concentration was weakly correlated with increased disease in wild mustard seedlings in both years (r = 0.51, 0.33, respectively). Growth of corn seedlings did not differ between the two soil treatments, suggesting that red clover green manure and compost may selectively reduce density and competitive ability of wild mustard in the field. Bioassay results corresponded well with emergence and shoot weight results from a related field study, indicating that this technique may be useful for screening potential soil treatments prior to field studies.     

Halothane binding to a G protein coupled receptor in retinal membranes by photoaffinity labeling

General anesthetics have been reported to alter the functions of G protein coupled receptor (GPCR) signaling systems. To determine whether these effects might be mediated by direct binding interactions with the GPCR or its associated G protein, we studied the binding character of halothane on mammalian rhodopsin, structurally the best understood GPCR, by using direct photoaffinity labeling with [(14)C]halothane. In the bleached bovine rod disk membranes (RDM), opsin and membrane lipids were dominantly photolabeled with [(14)C]halothane, but none of the three G protein subunits were labeled. In opsin itself, halothane labeling was inhibited by unlabeled halothane with an IC(50) of 0.9 mM and a Hill coefficient of -0.8. The stoichiometry was 1.1:1.0 (halothane:opsin molar ratio). The IC(50) values of isoflurane and 1-chloro-1,2, 2-trifluorocyclobutane were 5.0 and 15 mM, respectively. Ethanol had no effect on opsin labeling by halothane. A nonimmobilizer, 1, 2-dichlorohexafluorocyclobutane, inhibited halothane labeling by 50% at 0.05 mM. The present results demonstrate that halothane binds specifically and selectively to GPCRs in the RDM. The absence of halothane binding to any of the G protein subunits strongly suggests that the functional effects of halothane on GPCR signaling systems are mediated by direct interactions with receptor proteins.