Biomedical subjects

E C Chang

Publications and source records attributed to E C Chang.

At least 19 recordsLinked to original sources

PubMed2001

Optimism, pessimism, and positive and negative affectivity in middle-aged adults: a test of a cognitive-affective model of psychological adjustment.

This study attempted to address limitations in the understanding of optimism and pessimism among middle-aged adults. Specifically, a model of affectivity as a mediator of the link between outcome expectancies and psychological adjustment (life satisfaction and depressive symptoms) was presented and examined in a sample of 237 middle-aged adults. Consistent with a mediation model, results of path analyses indicated that optimism and pessimism (particularly the former) had significant direct and indirect links (by means of positive and negative affectivity) with depressive symptoms and life satisfaction. These results add to the small but growing literature identifying optimism and pessimism as important concomitants of psychological adjustment in more mature adults.

Adaptation, Psychological↗

PubMed2001

Cultural variations in optimistic and pessimistic bias: do Easterners really expect the worst and Westerners really expect the best when predicting future life events?

The authors compared levels of optimistic and pessimistic bias in the prediction of positive and negative life events between European Americans and Japanese. Study 1 showed that European Americans compared with Japanese were more likely to predict positive events to occur to self than to others. The opposite pattern emerged in the prediction of negative events. Study 2 replicated these cultural differences. Furthermore, positive associations emerged between predictions and occurrence of life events 2 months later for both European Americans and Japanese. Across both studies, results of within-groups analyses indicated that both groups expected negative events to be more likely to occur to others than to self (optimistic bias). In addition, Japanese expected positive events to be more likely to occur to others than to self (pessimistic bias). However, European Americans failed to show the expected optimistic bias for positive events.

Adult↗

PubMed2000

Yin6, a fission yeast Int6 homolog, complexes with Moe1 and plays a role in chromosome segregation.

The INT6 gene has been implicated in human breast cancer formation, but its function is unknown. We isolated an Int6 homolog from fission yeast, Yin6, by its binding to a conserved protein in the Ras pathway, Moe1. Yin6 and Moe1 converge on the same protein complex to promote microtubule instability/disassembly. Yin6 and Moe1 interact cooperatively: when either protein is absent, the other becomes mislocalized with decreased protein levels. Furthermore, whereas full-length human Int6 rescues the phenotypes of the yin6-null (yin6Delta) mutant cells and binds human Moe1, truncated Int6 proteins found in tumors do not. Importantly, yin6Delta alone impairs chromosome segregation weakly, but yin6Delta together with ras1Delta causes severe chromosome missegregation. These data support a model in which INT6 mutations in humans either alone or together with additional mutations, such as a RAS mutation, may contribute to tumorigenesis by altering genome stability.

Base Sequence↗

PubMed2000

A conserved interaction between Moe1 and Mal3 is important for proper spindle formation in Schizosaccharomyces pombe.

Moe1 is a conserved fission yeast protein that negatively affects microtubule stability/assembly. We conducted a two-hybrid screen to search for Moe1-binding proteins and isolated Mal3, a homologue of human EB1. We show that Moe1 and Mal3 expressed in bacteria form a complex and that Moe1 and Mal3 expressed in fission yeast cosediment with microtubules. Deletion of either moe1 or mal3 does not result in lethality; however, deletion of both moe1 and mal3 leads to cell death in the cold. The resulting cells appear to die of chromosome missegregation, which correlates with the presence of abnormal spindles. We investigated the cause for the formation of monopolar spindles and found that only one of the two spindle pole bodies (SPBs) contains gamma-tubulin, although both SPBs appear to be equal in size and properly inserted in the nuclear membrane. Moreover, the moe1 mal3 double null mutant in the cold contains abnormally short and abundant interphase microtubule bundles. These data suggest that Moe1 and Mal3 play a role in maintaining proper microtubule dynamics/integrity and distribution of gamma-tubulin to the SPBs during mitosis. Finally, we show that human Moe1 and EB1 can each rescue the phenotype of the moe1 mal3 double null mutant and form a complex, suggesting that these proteins are part of a well-conserved mechanism for regulating spindle functioning.

Carrier Proteins↗

PubMed2000

Fission yeast Ras1 effector Scd1 interacts with the spindle and affects its proper formation.

Ras1 GTPase is the Schizosaccharomyces pombe homolog of the mammalian Ha-Ras proto-oncoprotein. Ras1 interacts with Scd1 (aka Ral1), a presumptive guanine nucleotide exchange factor for Cdc42sp, to control organization of the cytoskeleton. In this study, we demonstrated that the scd1 deletion (scd1Delta) induced hypersensitivity to microtubule destabilizing drugs and instability of the minichromosome. Overexpression of scd1 induced formation of abnormal spindles and chromosome missegregation. The scd1 deletion worsened the defects of spindle formation in tubulin mutants; by contrast, it did not induce lethality in mutants defective in the spindle pole bodies. These genetic data suggest that Scd1 can interact with tubulin with substantial specificity to affect proper spindle formation and chromosome segregation. Subcellular localization data further illustrated that a GFP-Scd1 fusion protein can associate with the spindle. Finally, we showed that unlike ras1Delta and scd1Delta, byr2Delta (affecting the Ras1 effector for mating) is not synthetically lethal with the tubulin mutations. These data collectively suggest that the Ras1 pathway can impinge upon microtubules through Scd1, but not Byr2, to affect proper spindle formation and chromosome segregation.

Animals↗

PubMed2000

Planning for an annual episodic mass gathering: emergency department and clinic utilization in Yellowstone.

OBJECTIVE: Planning and providing emergency and primary care for a large transient population of visitors and employees in a national park can be problematic. Furthermore, planning for emergency and primary health care needs of visitors and itinerant workers in a wilderness area national park has not been well documented. A study was performed to analyze emergency and primary health care utilization in a national park. METHODS: Data was gathered from all patients presenting to Lake Hospital Emergency Department in Yellowstone in 1995, and a retrospective chart review was performed. RESULTS: Two distinct populations with different health care needs were identified. CONCLUSION: Utilization analysis revealed differences between conventional mass gatherings and the mass gatherings in Yellowstone. Because of the unique conditions and populations found in a wilderness area, conventional mass gathering emergency medical service models may not be an appropriate model for planning health care in a national park. Analysis of utilization data can help plan resources for emergency and primary health care for a park population.

Adolescent↗

PubMed1999

Moe1, a conserved protein in Schizosaccharomyces pombe, interacts with a Ras effector, Scd1, to affect proper spindle formation.

In fission yeast, Scd1/Ral1 is a putative guanine nucleotide exchange factor for Cdc42sp and also acts as a Ras1 effector necessary for the regulation of cytoskeleton organization. In this study, we have characterized a protein, Moe1, that binds directly to Scd1. A moe1 null (Delta) mutant exhibits numerous phenotypes indicative of abnormal microtubule functioning, including an abnormality in the spindle. moe1Delta mutants are resistant to microtubule destabilizing agents; moreover, moe1Delta rescued the growth defects of tubulin mutants containing unstable microtubules. These results suggest that Moe1 induces instability in microtubules. Biochemical and subcellular localization studies suggest that Moe1 and Scd1 colocalize in the nucleus. Furthermore, loss of function in Scd1 or Ras1 also induced abnormality in the spindle and is synthetically lethal with moe1Delta producing cells that lack a detectable spindle. These data demonstrate that Moe1 is a component of the Ras1 pathway necessary for proper spindle formation in the nucleus. Human and nematode Moe1 both can substitute for yeast Moe1, indicating that the function of Moe1 in spindle formation has been conserved substantially during evolution.

Carrier Proteins↗

PubMed1999

Effects of reduced-fat diets consumed ad libitum on intake of nutrients, particularly antioxidant vitamins.

OBJECTIVES: To determine whether a reduced-fat diet consumed ad libitum can achieve the recommended intakes of other macronutrients, fiber, and cholesterol and whether such a diet affects intake of other important micronutrients such as fat-soluble vitamins. DESIGN: Twelve-month, randomized, controlled trial of a reduced-fat, ad libitum diet vs usual diet. SUBJECTS: One hundred ten adults older than 40 years with glucose intolerance (2-hour blood glucose concentration = 7.0 to 11.0 mmol/L) who were selected from a previous workforce survey. INTERVENTION: Monthly small-group meetings aimed at identifying sources of dietary fat and ways to reduce fat consumption. MAIN OUTCOME MEASURES: Nutrient intakes derived from 3-day food diaries at the beginning and end of the study. Blood levels of retinol, alpha-tocopherol, and beta carotene at the end of the study. STATISTICAL ANALYSES PERFORMED: Unpaired t tests for determining changes in nutrient intake and antioxidant vitamin concentrations. Separate analyses were conducted with users of mineral and vitamin supplements and people who changed smoking status to reduce potential confounding. RESULTS: Fat intake decreased from 35% to 26% of energy in the reduced-fat diet group compared with a 2% decrease in the control group (P < .0001). Total energy intake also decreased in the 2 groups (-362 vs -59 kcal/day, P < .02). Those changes were reflected in a 3.1 +/- 4.7 kg (mean +/- standard deviation) weight loss in the intervention group compared with a 0.4 +/- 3.0 kg weight gain in the control group (P < .0001). There were no differences between groups in the changes in micronutrient intakes, except for an energy-adjusted increase in beta carotene intake in the reduced-fat diet group. Serum retinol and alpha-tocopherol concentrations were not different between the groups, but the reduced-fat diet group had higher beta carotene concentrations (P = .009). APPLICATIONS: A reduced-fat, ad libitum diet can be prescribed to improve overall macronutrient intake and achieve modest weight loss without sacrificing micronutrient intakes.

Body Mass Index↗

PubMed1998

Irrational beliefs, optimism, pessimism, and psychological distress: a preliminary examination of differential effects in a college population.

The present study compared the effects of irrational beliefs measured by the Survey of Personal Beliefs (SPB) and optimism and pessimism as measured by the revised Life Orientation Test (LOT-R) on depressive and anxious symptoms 6 weeks later. Results of analysis of variances for both measures of psychological distress indicated a significant main effect for pessimism only. Implications for Ellis Rational Emotive Therapy are discussed.

Adult↗

PubMed1998

Hope, problem-solving ability, and coping in a college student population: some implications for theory and practice.

The influence of high versus low hope on problem-solving ability and on coping with stressful academic and interpersonal situations was examined in 211 college students. Consistent with Snyder's (1995) model, high-hope students were found to have greater problem-solving abilities than low-hope students. High-hope students were also found to employ less disengagement strategies than low-hope students for coping with stressful academic situations. No difference was found in the strategies used by high- and low-hope students for coping with stressful interpersonal situations. Separate hierarchical regression analyses indicated that hope was an important predictor of both academic and interpersonal life satisfaction independent of coping activities. Implications of the present findings for both theory and practice are discussed.

Adaptation, Psychological↗

PubMed1998

Social problem-solving deficits and hopelessness, depression, and suicidal risk in college students and psychiatric inpatients.

The Social Problem-Solving Inventory-Revised was used to examine the relations between problem-solving abilities and hopelessness, depression, and suicidal risk in three different samples: undergraduate college students, general psychiatric inpatients, and suicidal psychiatric inpatients. A similar pattern of results was found in both college students and psychiatric patients: a negative problem orientation was most highly correlated with all three criterion variables, followed by either a positive problem orientation or an avoidance problem-solving style. Rational problem-solving skills emerged as an important predictor variable in the suicidal psychiatric sample. Support was found for a prediction model of suicidal risk that includes problem-solving deficits and hopelessness, with partial support being found for including depression in the model as well.

Adolescent↗

PubMed1998

What makes dreams positive or negative: relations to fundamental dimensions of positive and negative mood.

The present study examined the general emotional content of dreams reported by individuals who typically experience "positive" versus "negative" dreams. Self-reports of the 153 participants indicated that positive versus negative dreamers (ns = 42 and 24, respectively) generally experienced more positive emotions, e.g., joviality, self-assurance, and fewer negative emotions, e.g., fear, sadness. No differences were found in the self-reports of the participants in the experience of surprise, guilt, fatigue, and shyness between the groups, hence, positive and negative dreams do not appear to reflect simply more positive and fewer negative emotions, respectively.

Adolescent↗

PubMed1998

Locus of control and the fundamental dimensions of moods.

The present study examined the association between locus of control and positive and negative moods in 253 college students. Using the PANAS-X, designed by Watson and Clark, individuals scoring high on internal locus of control also scored higher across different dimensions of positive mood. Conversely, individuals scoring high on external locus of control had higher scores across different dimensions of negative mood.

Adolescent↗

PubMed1997

The Multidimensional Dream Inventory: preliminary evidence for validity and reliability.

The present study focused on the development of the Multidimensional Dream Inventory, an individual difference measure of dimensions of dreams. Items were administered to 151 college students. Consistent with expectations, results of an exploratory factor analysis of intercorrelations among items indicated a four-factor solution was appropriate. As a result, four dream-relevant scales were constructed, viz, Dream Importance, Dream Vividness, Dream Usefulness, and Dream Recall. In addition, these scales showed good internal consistency for research. Implications and uses for the Multidimensional Dream Inventory were discussed.

Adaptation, Psychological↗

PubMed1996

Relations between problem orientation and optimism, pessimism, and trait affectivity: a construct validation study.

This study investigated the construct validity of the Positive and Negative Problem Orientation scales of the Social Problem-Solving Inventory-Revised (SPSI-R) by examining the relations between these scales and measures of optimism, pessimism, and trait affectivity. Consistent with expectations based on social problem-solving theory, positive problem orientation was found to have a relatively large amount of variance in common with optimism and positive affectivity, and negative problem orientation was found to share a large amount of variance with pessimism and negative affectivity, but not enough to be considered redundant in either case. Positive problem orientation was found to add significant incremental validity to the prediction of adaptive problem-engagement coping even after partialing out the variance associated with optimism and positive affectivity. In addition, negative problem orientation was found to add unique variance to the prediction of psychological distress even after controlling for pessimism and negative affectivity.

Adaptation, Psychological↗

PubMed1996

Signaling in the yeast pheromone response pathway: specific and high-affinity interaction of the mitogen-activated protein (MAP) kinases Kss1 and Fus3 with the upstream MAP kinase kinase Ste7.

Kss1 and Fus3 are mitogen-activated protein kinases (MAPKs or ERKs), and Ste7 is their activating MAPK/ERK kinase (MEK), in the pheromone response pathway of Saccharomyces cerevisiae. To investigate the potential role of specific interactions between these enzymes during signaling, their ability to associate with each other was examined both in solution and in vivo. When synthesized by in vitro translation, Kss1 and Fus3 could each form a tight complex (Kd of approximately 5 nM) with Ste7 in the absence of any additional yeast proteins. These complexes were specific because neither Hog1 nor Mpk1 (two other yeast MAPKs), nor mammalian Erk2, was able to associate detectably with Ste7. Neither the kinase catalytic core of Ste7 nor the phosphoacceptor regions of Ste7 and Kss1 were necessary for complex formation. Ste7-Kss1 (and Ste7-Fus3) complexes were present in yeast cell extracts and were undiminished in extracts prepared from a ste5delta-ste11delta double mutant strain. In Ste7-Kss1 (or Ste7-Fus3) complexes isolated from naive or pheromone-treated cells, Ste7 phosphorylated Kss1 (or Fus3), and Kss1 (or Fus3) phosphorylated Ste7, in a pheromone-stimulated manner; dissociation of the high-affinity complex was shown to be required for either phosphorylation event. Deletions of Ste7 in the region required for its stable association with Kss1 and Fus3 in vitro significantly decreased (but did not eliminate) signaling in vivo. These findings suggest that the high-affinity and active site-independent binding observed in vitro facilitates signal transduction in vivo and suggest further that MEK-MAPK interactions may utilize a double-selection mechanism to ensure fidelity in signal transmission and to insulate one signaling pathway from another.

Base Sequence↗

PubMed1996

Preliminary study of health value as a moderator of the link between age and life satisfaction.

In the present study of the influence of health value as a potential moderator of age and life satisfaction. 157 undergraduate students (M = 20.8 yr.) completed a battery in which they provided demographic information and completed a number of different self report measures, including the Satisfaction With Life Scale and the Health Value Scale. A 2 (younger vs older) x 2 (high vs low health value) analysis of variance with life satisfaction as the dependent variable showed a significant man effect for health value and a significant interaction between age and health value but no man effect for age. These findings support health value as a moderator of the relation between age and psychological well-being. Implications for research and practice are discussed.

Adolescent↗

PubMed1996

How the value of health moderates the link between age and depressive symptoms: further evidence.

To extend earlier findings, this pilot study explored the role of self-reported value of health as a moderator between age and scores on the Beck Depression Inventory. 157 undergraduate students completed the Health Value Scale and the Beck inventory. There was no significant main effect for age with scores on the Beck inventory; however, scores on the Health Value Scale and their interaction with age were significant contributors to scores on the Beck Depression Inventory. These results are consistent with earlier findings. Implications for research and development are discussed.

Adolescent↗