Muscle fiber type-specific autophagy responses following an overnight fast and mixed meal ingestion in human skeletal muscle.

The aim of the present study was to investigate the fiber type-specific abundance of autophagy-related proteins after an overnight fast and following ingestion of a mixed meal in human skeletal muscle. Twelve overweight, healthy young male volunteers underwent a 3-h mixed meal tolerance test following an overnight fast. Blood samples were collected in the overnight-fasted state and throughout the 180-min postmeal period. Skeletal muscle biopsies were collected in the fasted state, and at 30 and 90 min after meal ingestion. Protein content of key autophagy markers and upstream signaling responses were measured in whole muscle and pooled single fibers using immunoblotting. In the fasted state, type I fibers displayed lower LC3B-I but higher LC3B-II abundance and higher LC3B-II/LC3B-I ratio compared with type II fibers (P < 0.05). However, there were no fiber type differences in p62/SQSTM1, unc-51 like autophagy activating kinase (ULK1), ATG5, or ATG12 (P > 0.05). Compared with the fasted state, there was a reduction in LC3B-II abundance, indicative of lower autophagosome content, in whole muscle and in both type I and type II fibers following meal ingestion (P < 0.05). This reduction in autophagosome content occurred alongside similar increases in p-AktS473 and p-mTORS2448 in both type I and type II muscle fibers (P < 0.05). In human skeletal muscle, type I fibers have a greater autophagosome content than type II fibers in the overnight-fasted state despite comparable abundance of other key upstream autophagy proteins. Autophagy is rapidly inhibited in both fiber types following the ingestion of a mixed meal.NEW & NOTEWORTHY This study examined the fiber type-specific content of key autophagy proteins in human muscle. We showed that markers of autophagosome content are higher in type I fibers in the overnight-fasted state, whereas autophagy is rapidly inhibited in both type I and type II fibers after the ingestion of a mixed meal.

On vagueness and parochialism in psychological research on groups.

Pietraszewski asserts that social psychological research on groups is too vague, tautological, and dependent on intuitions to be theoretically useful. We disagree. Pietraszewski's contribution is thought-provoking but also incomplete and guilty of many of the faults he attributes to others. Instead of rototilling the existing knowledge landscape, we urge for more integration of new and old ideas.

Whey Protein Augments Leucinemia and Postexercise p70S6K1 Activity Compared With a Hydrolyzed Collagen Blend When in Recovery From Training With Low Carbohydrate Availability.

We examined the effects of whey versus collagen protein on skeletal muscle cell signaling responses associated with mitochondrial biogenesis and protein synthesis in recovery from an acute training session completed with low carbohydrate availability. In a repeated-measures design (after adhering to a 36-hr exercise-dietary intervention to standardize preexercise muscle glycogen), eight males completed a 75-min nonexhaustive cycling protocol and consumed 22 g of a hydrolyzed collagen blend (COLLAGEN) or whey (WHEY) protein 45 min prior to exercise, 22 g during exercise, and 22 g immediately postexercise. Exercise decreased (p < .05) muscle glycogen content by comparable levels from pre- to postexercise in both trials (≈300-150 mmol/kg·dry weight). WHEY protein induced greater increases in plasma branched chain amino acids (p = .03) and leucine (p = .02) than COLLAGEN. Exercise induced (p < .05) similar increases in PGC-1α (fivefold) mRNA at 1.5 hr postexercise between conditions, although no effect of exercise (p > .05) was observed for p53, Parkin, and Beclin1 mRNA. Exercise suppressed (p < .05) p70S6K1 activity in both conditions immediately postexercise (≈25 fmol·min-1·mg-1). Postexercise feeding increased p70S6K1 activity at 1.5 hr postexercise (p < .05), the magnitude of which was greater (p < .05) in WHEY (180 ± 105 fmol·min-1·mg-1) versus COLLAGEN (73 ± 42 fmol·min-1·mg-1). We conclude that protein composition does not modulate markers of mitochondrial biogenesis when in recovery from a training session deliberately completed with low carbohydrate availability. By contrast, whey protein augments postexercise p70S6K activity compared with hydrolyzed collagen, as likely mediated via increased leucine availability.

Intergroup Context Moderates the Impact of White Americans' Identification on Racial Categorization of Ambiguous Faces.

We examined how the number of groups in a categorization task influences how White Americans categorize ambiguous faces. We investigated the strength of identity-driven ingroup overexclusion-wherein highly identified perceivers overexclude ambiguous members from the ingroup-proposing that, compared with dichotomous tasks (with only the ingroup and one outgroup), tasks with more outgroups attenuate identity-driven ingroup overexclusion (a dilution effect). Fourteen studies (n = 4,001) measured White Americans' racial identification and their categorizations of ambiguous faces and manipulated the categorization task to have two groups, three groups, or an unspecified number of groups (open-ended). In all three conditions, participants overexcluded faces from the White category on average. There was limited support for the dilution effect: identity-driven ingroup overexclusion was absent in the three-group task and only weakly supported in the open-ended task. The presence of multiple outgroups may dampen the impact of racial identity on race perceptions among White Americans.

Intramuscular lipid utilization during exercise: a systematic review, meta-analysis, and meta-regression.

Intramuscular lipid (IMCL) utilization during exercise was controversial as numerous studies did not observe a decline in IMCL content post-exercise when assessed in muscle biopsies using biochemical techniques. Contemporary techniques including immunofluorescence microscopy and 1H-magnetic resonance spectroscopy (1H-MRS) offer advantages over biochemical techniques. The primary aim of this systematic review, meta-analysis, and meta-regression was to examine the net degradation of IMCL in response to an acute bout of cycling exercise in humans, as assessed with different analytical approaches. A secondary aim was to explore the factors influencing IMCL degradation including feeding status, exercise variables, and participant characteristics. A total of 44 studies met the inclusion criteria using biochemical, immunofluorescence, and 1H-MRS techniques. A meta-analysis was completed using a random effects model and percentage change in IMCL content calculated from the standardized mean difference. Cycling exercise resulted in a net degradation of IMCL regardless of technique (total effect -23.7%, 95% CI = -28.7 to -18.7%) and there was no difference when comparing fasted versus fed-state exercise (P > 0.05). IMCL degradation using immunofluorescence techniques detected larger effects in type I fibers compared with whole muscle using biochemical techniques (P = 0.003) and in type I fibers compared with type II fibers (P < 0.001). Although IMCL degradation was associated with exercise duration, V̇o2max, and BMI, none of these factors independently related to the change in IMCL content. These findings provide strong evidence that the analytical approach can influence the assessment of IMCL degradation in human skeletal muscle in response to exercise.

The central role of entitativity in stereotypes of social categories and task groups.

Research indicates that people's intuitive beliefs about groups are organized according to a group typology (B. Lickel, D. L. Hamilton, & S. J. Sherman, 2001). In Study 1, the authors compared and contrasted people's spontaneous cognitive representations of two group types, task groups and social categories. Analyses revealed significant differences as well as commonalities in people's beliefs about the group types. Notably, perceivers used more abstract, enduring language and contextually rich descriptors when characterizing social categories than when describing task groups. In Study 2, the authors investigated the differential roles of distinct group perception variables (entitativity, homogeneity, essence, role differentiation, and agency) as predictors of stereotyping for the different group types. Entitativity and all of the group perception variables significantly predicted stereotyping for both social categories and task groups. However, perceptions of entitativity mediated the association between the group perception variables and stereotypic judgments. These findings demonstrate that laypeople hold stereotype-like mental representations of group types other than social categories and that entitativity plays a crucial mediating role in stereotyping across different types of groups.

Culture and group perception: dispositional and stereotypic inferences about novel and national groups.

In 3 studies, the authors tested the hypothesis that Chinese participants would view social groups as more entitative than would Americans and, as a result, would be more likely to infer personality traits on the basis of group membership--that is, to stereotype. In Study 1, Chinese participants made stronger stereotypic trait inferences than Americans did on the basis of a target's membership in a fictitious group. Studies 2 and 3 showed that Chinese participants perceived diverse groups as more entitative and attributed more internally consistent dispositions to groups and their members. Guided by culturally based lay theories about the entitative nature of groups, Chinese participants may stereotype more readily than do Americans when group membership is available as a source of dispositional inference.

Signaling Responses After Varying Sequencing of Strength and Endurance Training in a Fed State.

PURPOSE: To compare anabolic signaling responses to differing sequences of concurrent strength and endurance training in a fed state. METHODS: Eighteen resistance-trained men were randomly assigned to the following experimental conditions: strength training (ST), strength followed by endurance training (ST-END), or endurance followed by strength training (END-ST). Muscle tissue samples were taken from the vastus lateralis before each exercise protocol, on cessation of exercise, and 1 h after cessation of strength training. Tissue was analyzed for total and phosphorylated (p-) signaling proteins linked to the mTOR and AMPK networks. RESULTS: Strength-training performance was similar between ST, ST-END, and END-ST. p-S6k1 was elevated from baseline 1 h posttraining in ST and ST-END (both P < .05). p-4E-BP1 was significantly lower than baseline post-ST (P = .01), whereas at 1 h postexercise in the ST-END condition p-4E-BP1 was significantly greater than postexercise (P = .04). p-ACC was elevated from baseline both postexercise and 1 h postexercise (both P < .05) in the END-ST condition. AMPK, mTOR, p38, PKB, and eEF2 responded similarly to ST, ST-END, and END-ST. Signaling responses to ST, ST-END, and END were largely similar. As such it cannot be ascertained which sequence of concurrent strength and endurance training is most favorable in promoting anabolic signaling. CONCLUSIONS: In the case of the current study an acute bout of concurrent training of differing sequences elicited similar responses of the AMPK and mTOR networks.

Understanding diversity: the importance of social acceptance.

Two studies investigated how people define and perceive diversity in the historically majority-group dominated contexts of business and academia. We hypothesized that individuals construe diversity as both the numeric representation of racial minorities and the social acceptance of racial minorities within a group. In Study 1, undergraduates' (especially minorities') perceptions of campus diversity were predicted by perceived social acceptance on a college campus, above and beyond perceived minority representation. Study 2 showed that increases in a company's representation and social acceptance independently led to increases in perceived diversity of the company among Whites. Among non-Whites, representation and social acceptance only increased perceived diversity of the company when both qualities were high. Together these findings demonstrate the importance of both representation and social acceptance to the achievement of diversity in groups and that perceiver race influences the relative importance of these two components of diversity.

BACE1 activity impairs neuronal glucose oxidation: rescue by beta-hydroxybutyrate and lipoic acid.

Glucose hypometabolism and impaired mitochondrial function in neurons have been suggested to play early and perhaps causative roles in Alzheimer's disease (AD) pathogenesis. Activity of the aspartic acid protease, beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1), responsible for beta amyloid peptide generation, has recently been demonstrated to modify glucose metabolism. We therefore examined, using a human neuroblastoma (SH-SY5Y) cell line, whether increased BACE1 activity is responsible for a reduction in cellular glucose metabolism. Overexpression of active BACE1, but not a protease-dead mutant BACE1, protein in SH-SY5Y cells reduced glucose oxidation and the basal oxygen consumption rate, which was associated with a compensatory increase in glycolysis. Increased BACE1 activity had no effect on the mitochondrial electron transfer process but was found to diminish substrate delivery to the mitochondria by inhibition of key mitochondrial decarboxylation reaction enzymes. This BACE1 activity-dependent deficit in glucose oxidation was alleviated by the presence of beta hydroxybutyrate or α-lipoic acid. Consequently our data indicate that raised cellular BACE1 activity drives reduced glucose oxidation in a human neuronal cell line through impairments in the activity of specific tricarboxylic acid cycle enzymes. Because this bioenergetic deficit is recoverable by neutraceutical compounds we suggest that such agents, perhaps in conjunction with BACE1 inhibitors, may be an effective therapeutic strategy in the early-stage management or treatment of AD.

Sowing the seeds of stereotypes: Spontaneous inferences about groups.

Although dispositional inferences may be consciously drawn from the trait implications of observed behavior, abundant research has shown that people also spontaneously infer trait dispositions simply in the process of comprehending behavior. These spontaneous trait inferences (STIs) can occur without intention or awareness. All research on STIs has studied STIs based on behaviors of individual persons. Yet important aspects of social life occur in groups, and people regularly perceive groups engaging in coordinated action. We propose that perceivers make spontaneous trait inferences about groups (STIGs), parallel to the STIs formed about individuals. In 5 experiments we showed that (a) perceivers made STIGs comparable with STIs about individuals (based on the same behaviors), (b) a cognitive load manipulation did not affect the occurrence of STIGs, (c) STIGs occurred for groups varying in entitativity, (d) STIGs influenced perceivers' impression ratings of those groups, and (e) STIG-based group impressions generalized to new group members. These experiments provide the first evidence for STIGs, a process that may contribute to the formation of spontaneous group impressions. Implications for stereotype formation are discussed.

Gendered Facial Cues Influence Race Categorizations.

Race and gender categories, although long presumed to be perceived independently, are inextricably tethered in social perception due in part to natural confounding of phenotypic cues. We predicted that target gender would affect race categorizations. Consistent with this hypothesis, feminine faces compelled White categorizations, and masculine faces compelled Asian or Black categorizations of racially ambiguous targets (Study 1), monoracial targets (Study 2), and real facial photographs (Study 3). The efficiency of judgments varied concomitantly. White categorizations were rendered more rapidly for feminine, relative to masculine faces, but the opposite was true for Asian and Black categorizations (Studies 1-3). Moreover, the effect of gender on categorization efficiency was compelled by racial phenotypicality for Black targets (Study 3). Finally, when targets' race prototypicality was held constant, gender still influenced race categorizations (Study 4). These findings indicate that race categorizations are biased by presumably unrelated gender cues.

The spontaneous use of a group typology as an organizing principle in memory.

Five studies investigated the spontaneous use of group typology in encoding information about various social groups. Participants saw faces or behaviors along with a label indicating the group membership of the face or the behavior. Labels corresponded to 2 groups each of 3 group types (i.e., 2 intimacy groups, 2 task-oriented groups, and 2 social categories). Recognition results showed more within-group-type errors than between-group-types errors. A free-recall task replicated these results, as the sequence of remembering items showed that memory organization reflected the group typology. A final study investigated the effects of group typology on the speed and accuracy of category membership verification. Results demonstrate the spontaneous use of an implicit group typology and its influence on the cognitive organization of information about groups.

Perceived entitativity, stereotype formation, and the interchangeability of group members.

The authors investigated the effects of perceived entitativity of a group on the processing of behavioral information about individual group members and the extent to which such information was transferred to other group members. The results of 3 experiments using a savings-in-relearning paradigm showed that trait inferences about a group member, based on that member's behavior, were stronger for low entitative groups and for collections of individuals. However, the transference of traits from 1 group member to other members of the group was stronger for high entitative groups. These results provide strong evidence that the perception of high entitativity involves the abstraction of a stereotype of the group and the transfer of that stereotype across all group members. Implications for group impression formation and stereotyping are discussed.

Exhaustive and heuristic retrieval processes in person cognition: further tests of the TRAP model.

The twofold retrieval by associative pathways (TRAP) model (L. Garcia-Marques & D. L. Hamilton, 1996) proposes that two distinct modes of retrieval typically underlie recall and frequency estimation. The model accounts for the simultaneous occurrence of greater recall of incongruent information and higher frequency estimation of congruent information. Three experiments provided further tests of the TRAP model. Experiment 1 manipulated cognitive load (at encoding and at retrieval) and the selectivity of the retrieval goal. Under either high load or a selective retrieval goal, incongruent items ceased to be better recalled. Experiment 2 manipulated the accessibility of expectancy-congruent, -incongruent, or -neutral episodes and found corresponding effects in frequency estimates. Finally, Experiment 3 showed that providing part-list retrieval cues inhibits recall but increases frequency estimates. The TRAP model predicted these results.

A case of collective responsibility: who else was to blame for the Columbine high school shootings?

Two studies examined perceptions of collective responsibility for the April 20, 1999, shootings at Columbine High School in Littleton, Colorado. Collective responsibility refers to the perception that others, besides the wrongdoers themselves, are responsible for the event. In Study 1, the authors assessed perceptions of the shooters' parents and their peer group (the Trenchcoat Mafia), whereas Study 2 tested perceptions of collective responsibility across a range of groups. In both studies, perceptions of a target group's entitativity predicted judgments of collective responsibility. This relationship was mediated by two situational construals that justify applying collective responsibility: responsibility by commission (encouraging or facilitating the event) and responsibility by omission (failing to prevent the event). Study 2 also determined that perceptions of authority predicted judgments of collective responsibility for the Columbine shootings and was mediated by inferences of omission. Future directions in collective responsibility research are discussed.

Motivation to control prejudice predicts categorization of multiracials.

Multiracial individuals often do not easily fit into existing racial categories. Perceivers may adopt a novel racial category to categorize multiracial targets, but their willingness to do so may depend on their motivations. We investigated whether perceivers' levels of internal motivation to control prejudice (IMS) and external motivation to control prejudice (EMS) predicted their likelihood of categorizing Black-White multiracial faces as Multiracial. Across four studies, IMS positively predicted perceivers' categorizations of multiracial faces as Multiracial. The association between IMS and Multiracial categorizations was strongest when faces were most racially ambiguous. Explicit prejudice, implicit prejudice, and interracial contact were ruled out as explanations for the relationship between IMS and Multiracial categorizations. EMS may be negatively associated with the use of the Multiracial category. Therefore, perceivers' motivations to control prejudice have important implications for racial categorization processes.

Enhancing the comparability between part-list cueing and collaborative recall: a gradual part-list cueing paradigm.

The effects of part-list cueing and of collaborative recall in memory performance have been recently addressed as parallel phenomena. Notably they both impair recall (and boost frequency estimates) and they have been explained by the same underlying mechanisms. However, the comparability between the two paradigms is hindered by a number of procedural differences. The main contribution of this paper is the introduction of a new paradigm that makes standard part-list cueing and collaborative recall more comparable. In our study we compared free recall and frequency estimates of participants in a non-cueing condition with the same performance in a standard part-list cueing condition and in a condition in which part-list cues were gradually presented during recall (as it occurs in collaborative recall). Results indicate that the effects of part-list cueing continued to be reliable in both cueing conditions. Namely, recall was impaired and frequency estimates were boosted relatively to a non-cueing condition. The results obtained with this new method that enhances the direct comparability of the two paradigms provide further evidence for the parallel between the two effects.