PubMed Health⌕ Search

Biomedical subjects

Katherine White

Publications and source records attributed to Katherine White.

10 recordsLinked to original sources
PubMed2006

Computational study of iminium ion formation: effects of amine structure.

Density functional calculations are used to explore the formation of iminium ions from secondary amines and acrolein and the subsequent reactivity of the resulting iminium ions. After establishing a feasible profile for this reaction in simulated experimental conditions, we focus on the effect of variation in amine structure on calculated barriers. This analysis shows that incorporation of a heteroatom (N or O) in the alpha-position to the reactive amine results in significantly reduced energy barriers, as does an electron-withdrawing group (carbonyl or thiocarbonyl) in the beta-position. Electron density analysis is used to monitor reactions at a detailed level, and to identify important intermolecular interactions at both minima and transition states. Barriers to reaction are linked to calculated proton affinities of secondary amines, suggesting that the relative ease of protonation-deprotonation of the amine is a key property of effective catalysts. Moreover, barriers for subsequent Diels-Alder reaction of iminium ions with cyclopentadiene are lower than for their formation, suggesting that formation may be the rate determining step in the catalytic cycle.

Journal Article↗
PubMed2005

Culture and social comparison seeking: the role of self-motives.

Three studies examined the relation between cultural background and social comparison seeking. Compared to European Canadians, Asian Canadians sought more social comparisons, particularly those that were upward (Study 1), more social comparisons after failure (Study 2), and more social comparisons after failure when the opportunity for self-improvement was made salient (Study 3). Taken together, these data spotlight Asian Canadians' interest in social comparisons that allow for self-improvement.

Adult↗
PubMed2005

Looking on the bright side: downward counterfactual thinking in response to negative life events.

Past research has found that downward counterfactual thoughts are rarely generated in response to negative life events. However, the authors suggest that under conditions in which self-enhancement motives are prominent, downward counterfactuals will be more frequent than upward counterfactuals. When motives were explicitly manipulated (Study 1), people generated more downward counterfactuals in the self-enhancement than in the self-improvement and control conditions. In Study 2, among those chronically more motivated to self-enhance (i.e., European Canadians), a manipulation of event severity led to the generation of more downward than upward counterfactuals. This finding was mediated by the desire for self-enhancement. In Study 3, cultural background and the opportunity for self-affirmation were related to the generation of downward counterfactuals in expected ways. Implications of these findings are discussed.

Adaptation, Psychological↗
PubMed2004

Stem cells 101.

Explore the source record for details and available documents.

Ethics, Medical↗
PubMed2003

Protective immunity induced with malaria vaccine, RTS,S, is linked to Plasmodium falciparum circumsporozoite protein-specific CD4+ and CD8+ T cells producing IFN-gamma.

The Plasmodium falciparum circumsporozoite (CS) protein-based pre-erythrocytic stage vaccine, RTS,S, induces a high level of protection against experimental sporozoite challenge. The immune mechanisms that constitute protection are only partially understood, but are presumed to rely on Abs and T cell responses. In the present study we compared CS protein peptide-recalled IFN-gamma reactivity of pre- and RTS,S-immune lymphocytes from 20 subjects vaccinated with RTS,S. We observed elevated IFN-gamma in subjects protected by RTS,S; moreover, both CD4(+) and CD8(+) T cells produced IFN-gamma in response to CS protein peptides. Significantly, protracted protection, albeit observed only in two of seven subjects, was associated with sustained IFN-gamma response. This is the first study demonstrating correlation in a controlled Plasmodia sporozoite challenge study between protection induced by a recombinant malaria vaccine and Ag-specific T cell responses. Field-based malaria vaccine studies are in progress to validate the establishment of this cellular response as a possible in vitro correlate of protective immunity to exo-erythrocytic stage malaria vaccines.

Amino Acid Sequence↗
PubMed2003

Intuitions about situational correction in self and others.

People's attributional phenomenology is likely to be characterized by effortful situational correction. Drawing on this phenomenology and on people's desire to view themselves more favorably than others, the authors hypothesized that people expect others to engage in less situational correction than themselves and to make more extreme dispositional attributions for constrained actors' behavior. In 2 studies, people expected their peers to make more extreme dispositional inferences than they did themselves for a situationally constrained actor's behavior. People's expectation that they engage in more situational correction than their peers was diminished among Japanese participants, who have less desire to view themselves as superior to their peers (Study 3), and among participants who were led to view dispositional attributions more favorably than situational attributions (Study 4).

Adult↗
PubMed2003

Opsonization by antigen-specific antibodies as a mechanism of protective immunity induced by Plasmodium falciparum circumsporozoite protein-based vaccine.

Recently conducted trials involving the Plasmodium falciparum circumsporozoite (CS) protein-based RTS,S malaria vaccine yielded unprecedented protection against a challenge with infectious sporozoites (spzs). The RTS,S vaccine induced high titres of CS protein-specific antibodies (Abs) in many of the protected volunteers, but the contribution of these Abs to protection remains unknown. Because opsonization by Ab promotes the uptake and destruction of spzs by monocytes and macrophages in both rodent and primate malaria, we asked if the RTS,S-induced Abs have antigen-specific opsonizing activity. Screening plasma from a large number of subjects using spzs was impractical, therefore we developed an alternative assay based on cytofluorometry that allowed the detection of fluoresceinated-Ag-Ab complexes endocytosed by the FcR+ THP-1 human monocyte line. The results showed that plasma samples from RTS,S-immunized subjects contained opsonizing CS protein-specific Abs and the endocytic activity of these Abs in protected subjects was significantly higher than in subjects who were susceptible to infection with spzs. We also demonstrated by electron microscopy that live spzs exposed to RTS,S-immune plasma could be internalized by the THP-1 cells. These results suggest that opsonization by CS protein-specific Abs might be one of the mechanisms that contributes to RTS,S-induced protective immunity.

Animals↗
PubMed2002

Maximizing versus satisficing: happiness is a matter of choice.

Can people feel worse off as the options they face increase? The present studies suggest that some people--maximizers--can. Study 1 reported a Maximization Scale, which measures individual differences in desire to maximize. Seven samples revealed negative correlations between maximization and happiness, optimism, self-esteem, and life satisfaction, and positive correlations between maximization and depression, perfectionism, and regret. Study 2 found maximizers less satisfied than nonmaximizers (satisficers) with consumer decisions, and more likely to engage in social comparison. Study 3 found maximizers more adversely affected by upward social comparison. Study 4 found maximizers more sensitive to regret and less satisfied in an ultimatum bargaining game. The interaction between maximizing and choice is discussed in terms of regret, adaptation, and self-blame.

Adaptation, Psychological↗