Negative and positive selection of antigen-specific cytotoxic T lymphocytes affected by the α3 domain of MHC I molecules

THE α1 and α2 domains of major histocompatibility complex (MHC) class I molecules function in the binding and presentation of foreign peptides to the T-cell antigen receptor and control both negative and positive selection of the T-cell repertoire. Although the α3 domain of class I is not involved in peptide binding, it does interact with the T-cell accessory molecule, CDS. CDS is important in the selection of T cells as anti-CDS antibody injected into perinatal mice interfers with this process. We previously used a hybrid class I molecule with the α1/α2 domains from L^d and the α3 domain from Q7^b and showed that this molecule binds an L^d-restricted peptide but does not interact with CD8-dependent cytotoxic T lymphocytes. Expression of this molecule in transgenic mice fails to negatively select a subpopulation of anti-L^d cytotoxic T lymphocytes. In addition, positive selection of virus-specific L^d-restricted cytotoxic T lymphocytes does not occur. We conclude that besides the α1/α2 domains of class I, the α3 domain plays an important part in both positive and negative selection of antigen-specific cells

Polysomnographic and Subjective Sleep Predictors of Alcoholic Relapse

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65219/1/j.1530-0277.1998.tb03995.x.pd

Axons Amplify Somatic Incomplete Spikes into Uniform Amplitudes in Mouse Cortical Pyramidal Neurons

BACKGROUND: Action potentials are the essential unit of neuronal encoding. Somatic sequential spikes in the central nervous system appear various in amplitudes. To be effective neuronal codes, these spikes should be propagated to axonal terminals where they activate the synapses and drive postsynaptic neurons. It remains unclear whether these effective neuronal codes are based on spike timing orders and/or amplitudes. METHODOLOGY/PRINCIPAL FINDINGS: We investigated this fundamental issue by simultaneously recording the axon versus soma of identical neurons and presynaptic vs. postsynaptic neurons in the cortical slices. The axons enable somatic spikes in low amplitude be enlarged, which activate synaptic transmission in consistent patterns. This facilitation in the propagation of sequential spikes through the axons is mechanistically founded by the short refractory periods, large currents and high opening probability of axonal voltage-gated sodium channels. CONCLUSION/SIGNIFICANCE: An amplification of somatic incomplete spikes into axonal complete ones makes sequential spikes to activate consistent synaptic transmission. Therefore, neuronal encoding is likely based on spike timing order, instead of graded analogues

Sadness, anger, and frustration: Gendered patterns in early adolescents' and their parents' emotion talk

The present study was designed to investigate gender patterns in early adolescents' and their parents' verbal expression of three gender-stereotyped emotions: anger, sadness, and frustration. Parents and their early adolescent children discussed four interpersonal dilemmas and answered questions regarding those dilemmas in mother-child and father-child dyads. Consistent with previous literature regarding gender stereotypes in emotion expression, daughters used a higher frequency of emotion words than sons did during conversations with their mothers and fathers. Additional analyses regarding the three specific emotions under investigation, however, revealed findings that were inconsistent with conventional gender stereotypes. Contrary to expectations, in conversations with fathers, sons used a higher proportion of references to sadness than did daughters. Daughters used a higher proportion of references to frustration than did sons in their conversations with both mothers and fathers. Mothers and fathers used a higher proportion of references to frustration with daughters than with sons. No gender differences were found in parents' or children's references to anger. The results call into question culturally accepted gender stereotypes about sadness, anger, and frustration. © 2006 Springer Science+Business Media, LLC

Does Discovery-Based Instruction Enhance Learning?

Discovery learning approaches to education have recently come under scrutiny (Tobias & Duffy, 2009), with many studies indicating limitations to discovery learning practices. Therefore, 2 meta-analyses were conducted using a sample of 164 studies: The 1st examined the effects of unassisted discovery learning versus explicit instruction, and the 2nd examined the effects of enhanced and/or assisted discovery versus other types of instruction (e.g., explicit, unassisted discovery). Random effects analyses of 580 comparisons revealed that outcomes were favorable for explicit instruction when compared with unassisted discovery under most conditions (d = -0.38, 95% CI [-.44, -.31]). In contrast, analyses of 360 comparisons revealed that outcomes were favorable for enhanced discovery when compared with other forms of instruction (d = 0.30, 95% CI [.23, .36]). The findings suggest that unassisted discovery does not benefit learners, whereas feedback, worked examples, scaffolding, and elicited explanations do. © 2010 American Psychological Association

Perspective taking in children's narratives about jealousy

This study explored relationships between perspective-taking, emotion understanding, and children's narrative abilities. Younger (23 5-/6-year-olds) and older (24 7-/8-year-olds) children generated fictional narratives, using a wordless picture book, about a frog experiencing jealousy. Children's emotion understanding was assessed through a standardized test of emotion comprehension and their ability to convey the jealousy theme of the story. Perspective-taking ability was assessed with respect to children's use of narrative evaluation (i.e., narrative coherence, mental state language, supplementary evaluative speech, use of subjective language, and placement of emotion expression). Older children scored higher than younger children on emotion comprehension and on understanding the story's complex emotional theme, including the ability to identify a rival. They were more advanced in perspective-taking abilities, and selectively used emotion expressions to highlight story episodes. Subjective perspective taking and narrative coherence were predictive of children's elaboration of the jealousy theme. Use of supplementary evaluative speech, in turn, was predictive of both subjective perspective taking and narrative coherence. © 2010 The British Psychological Society