Incidental exposure to hedonic and healthy food features affects food preferences one day later.

Memories acquired incidentally from exposure to food information in the environment may often become active to later affect food preferences. Because conscious use of these memories is not requested or required, these incidental learning effects constitute a form of indirect memory. In an experiment using a novel food preference paradigm (n = 617), we found that brief incidental exposure to hedonic versus healthy food features indirectly affected food preferences a day later, explaining approximately 10% of the variance in preferences for tasty versus healthy foods. It follows that brief incidental exposure to food information can affect food preferences indirectly for at least a day. When hedonic and health exposure were each compared to a no-exposure baseline, a general effect of hedonic exposure emerged across individuals, whereas health exposure only affected food preferences for high-BMI individuals. This pattern suggests that focusing attention on hedonic food features engages common affective processes across the general population, whereas focusing attention on healthy food features engages eating restraint goals associated with high BMI. Additionally, incidental exposure to food features primarily changed preferences for infrequently consumed foods, having less impact on habitually consumed foods. These findings offer insight into how hedonic information in the obesogenic food environment contributes to unhealthy eating behavior that leads to overweight and obesity. These findings further motivate the development of interventions that counteract the effects of exposure to hedonic food information and that broaden the effects of exposure to healthy food information.

Determinants in CaV1 channels that regulate the Ca2+ sensitivity of bound calmodulin.

Calmodulin binds to IQ motifs in the alpha(1) subunit of Ca(V)1.1 and Ca(V)1.2, but the affinities of calmodulin for the motif and for Ca(2+) are higher when bound to Ca(V)1.2 IQ. The Ca(V)1.1 IQ and Ca(V)1.2 IQ sequences differ by four amino acids. We determined the structure of calmodulin bound to Ca(V)1.1 IQ and compared it with that of calmodulin bound to Ca(V)1.2 IQ. Four methionines in Ca(2+)-calmodulin form a hydrophobic binding pocket for the peptide, but only one of the four nonconserved amino acids (His-1532 of Ca(V)1.1 and Tyr-1675 of Ca(V)1.2) contacts this calmodulin pocket. However, Tyr-1675 in Ca(V)1.2 contributes only modestly to the higher affinity of this peptide for calmodulin; the other three amino acids in Ca(V)1.2 contribute significantly to the difference in the Ca(2+) affinity of the bound calmodulin despite having no direct contact with calmodulin. Those residues appear to allow an interaction with calmodulin with one lobe Ca(2+)-bound and one lobe Ca(2+)-free. Our data also provide evidence for lobe-lobe interactions in calmodulin bound to Ca(V)1.2.

Crystal structure of dimeric cardiac L-type calcium channel regulatory domains bridged by Ca2+* calmodulins.

Voltage-dependent calcium channels (Ca(V)) open in response to changes in membrane potential, but their activity is modulated by Ca(2+) binding to calmodulin (CaM). Structural studies of this family of channels have focused on CaM bound to the IQ motif; however, the minimal differences between structures cannot adequately describe CaM's role in the regulation of these channels. We report a unique crystal structure of a 77-residue fragment of the Ca(V)1.2 alpha(1) subunit carboxyl terminus, which includes a tandem of the pre-IQ and IQ domains, in complex with Ca(2+).CaM in 2 distinct binding modes. The structure of the Ca(V)1.2 fragment is an unusual dimer of 2 coiled-coiled pre-IQ regions bridged by 2 Ca(2+).CaMs interacting with the pre-IQ regions and a canonical Ca(V)1-IQ-Ca(2+).CaM complex. Native Ca(V)1.2 channels are shown to be a mixture of monomers/dimers and a point mutation in the pre-IQ region predicted to abolish the coiled-coil structure significantly reduces Ca(2+)-dependent inactivation of heterologously expressed Ca(V)1.2 channels.

Validation of a single-stage submaximal treadmill walking test.

The single-stage treadmill walking test of Ebbeling et al. is commonly used to predict maximal oxygen consumption (.VO(2max)) from a submaximal effort between 50% and 70% of the participant's age-predicted maximum heart rate. The purpose of this study was to determine if this submaximal test correctly predicts .VO(2max) at the low (50% of maximum heart rate) and high (70% of maximum heart rate) ends of the specified heart rate range for males and females aged 18 - 55 years. Each of the 34 participants completed one low-intensity and one high-intensity trial. The two trials resulted in significantly different estimates of .VO(2max) (low-intensity trial: mean 40.5 ml . kg(-1) . min(-1), s = 9.3; high-intensity trial: 47.5 ml . kg(-1) . min(-1), s = 8.8; P < 0.01). A subset of 22 participants concluded their second trial with a .VO(2max) test (mean 47.9 ml . kg(-1) . min(-1), s = 8.9). The low-intensity trial underestimated (mean difference = -3.5 ml . kg(-1) . min(-1); 95% CI = -6.4 to -0.6 ml . kg(-1) . min(-1); P = 0.02) and the high-intensity trial overestimated (mean difference = 3.5 ml . kg(-1) . min(-1); 95% CI = 1.1 to 6.0 ml . kg(-1) . min(-1); P = 0.01) the measured .VO(2max). The predictive validity of Ebbeling and colleagues' single-stage submaximal treadmill walking test is diminished when performed at the extremes of the specified heart rate range.

Structure of calmodulin bound to the hydrophobic IQ domain of the cardiac Ca(v)1.2 calcium channel.

Ca2+-dependent inactivation (CDI) and facilitation (CDF) of the Ca(v)1.2 Ca2+ channel require calmodulin binding to a putative IQ motif in the carboxy-terminal tail of the pore-forming subunit. We present the 1.45 A crystal structure of Ca2+-calmodulin bound to a 21 residue peptide corresponding to the IQ domain of Ca(v)1.2. This structure shows that parallel binding of calmodulin to the IQ domain is governed by hydrophobic interactions. Mutations of residues I1672 and Q1673 in the peptide to alanines, which abolish CDI but not CDF in the channel, do not greatly alter the structure. Both lobes of Ca2+-saturated CaM bind to the IQ peptide but isoleucine 1672, thought to form an intramolecular interaction that drives CDI, is buried. These findings suggest that this structure could represent the conformation that calmodulin assumes in CDF.

Religious orientation, aging, and blood pressure reactivity to interpersonal and cognitive stressors.

BACKGROUND: Research on religion and health suggests general health benefits for those who are more religiously involved. Particular aspects of religiosity that may influence this finding, however, have not been sufficiently investigated. PURPOSE: This study was designed to explore the relationship between religious orientation (intrinsic, extrinsic) and blood pressure reactivity among older (over 60 years) and younger (18-24 years) adults exposed to two qualitatively different laboratory stressors (cognitive, interpersonal). METHODS: Participants were categorized as exhibiting either a predominantly intrinsic or extrinsic religious orientation based on scores on the Religious Orientation Scale. They were subsequently exposed (in counterbalanced order) to two laboratory stressors that varied in terms of whether an interpersonal confrontation was involved. Measures of blood pressure were obtained at baseline and during stressor presentation. RESULTS: Analyses indicated that older extrinsically religious individuals demonstrated exaggerated reactivity compared to younger participants and older intrinsically religious individuals. Older intrinsically religious participants did not differ from younger persons. Similar results were found for analysis of baseline data. Extrinsic participants had greater reactivity during the interpersonal confrontation condition than did intrinsic individuals. CONCLUSIONS: These findings suggest that religious orientation may be an important variable to study regarding cardiovascular reactivity in, particularly, older adults.

A closed compact structure of native Ca(2+)-calmodulin.

Calmodulin has been a subject of intense scrutiny since its discovery because of its unusual properties in regulating the functions of about 100 diverse target enzymes and structural proteins. The original and to date only crystal conformation of native eukaryotic Ca(2+)-calmodulin (Ca(2+)-CaM) is a very extended molecule with two widely separated globular domains linked by an exposed long helix. Here we report the 1.7 A X-ray structure of a new native Ca(2+)-CaM that is in a compact ellipsoidal conformation and shows a sharp bend in the linker helix and a more contracted N-terminal domain. This conformation may offer advantages for recognition of kinase-type calmodulin targets or small organic molecule drugs.