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Biomedical subjects

P Kwon

Publications and source records attributed to P Kwon.

11 recordsLinked to original sources
PubMed2001

Mammalian histone deacetylase 1 protein is posttranslationally modified by phosphorylation.

HDAC1, a member of the histone deacetylase family, is involved in transcription regulation through the modification of chromatin structure. Several studies also implicated HDAC1 in tumorigenesis. Much attention has been concentrated on protein-protein interactions involving HDAC1 and the possibility that posttranslational modifications may occur in mammalian HDAC1 proteins has not been carefully and systematically investigated. In this study, we utilized in vivo labeling assays to demonstrate that both human and murine HDAC1 proteins are phosphorylated in cells. Assays using HDAC1 deletion mutants indicated that phosphorylation occurs in its C-terminal domain. cAMP-dependent kinase and casein kinase II, but not protein kinase C, cdc2, or MAP kinase, could phosphorylate HDAC1 in vitro, although HDAC1 contains several protein kinase C consensus sites. We also found that phosphorylation did not influence HDAC1 enzymatic activity using a human histone H4 N-terminal peptide as the substrate. Interestingly, HDAC1-FLAG fusion protein immunoprecipitated from transfected cells was found to be in association with a kinase activity, providing an in vitro assay for further studies of this posttranslational modification.

Amino Acid Sequence↗
PubMed2001

Sociotropy and autonomy: preliminary evidence for construct validity using TAT narratives.

In this investigation, we evaluated the construct validity of sociotropy and autonomy as assessed by the revised Personal Style Inventory (PSI; Robins et al., 1994). Stories given to 6 cards of the Thematic Apperception Test (Murray, 1943) were coded for need for Achievement (McClelland, Atkinson, Clark, & Lowell, 1953) and need for Affiliation (Heyns, Veroff, & Atkinson, 1958). These scores were correlated with PSI Sociotropy and Autonomy, along with their component subscales. The construct validity of Sociotropy, Autonomy, and 5 of 6 component subscales were supported as hypoth sized. Consistent with past research, there was no support for the construct validity of the Perfectionism/Self-Criticism subscale of Autonomy. In addition, separate analyses by gender suggested that the construct validity of sociotropy may be greater for women than for men. The results represent an important finding in that nonquestionnaire measures of interpersonal and achievement-related concerns were found to support the validity of the PSI, a need identified by the questionnaire's authors.

Adolescent↗
PubMed2000

Attributional style and defense mechanisms: a synthesis of cognitive and psychodynamic factors in depression.

In a study involving 160 undergraduates, we tested the hypothesis that attributional style and defense style would have interactive effects on depressive symptoms. Consistent with this hypothesis, both negative attributional style and low defense maturity were associated with depressive symptoms, both as main effects and in interaction. Negative attributional style was associated with depressive symptoms primarily when accompanied by low defense maturity. The presence of a positive attributional style reduced the relation between low defense maturity and depressive symptoms, and the presence of high defense maturity reduced the relation between a negative attributional style and depressive symptoms. In addition, high defense immaturity was shown to be a possible mediator of the relation between negative attributional style and depressive symptoms. Clinical implications for psychotherapy integration are discussed.

Adolescent↗
PubMed2000

Hope and dysphoria: the moderating role of defense mechanisms.

It was hypothesized that the adaptive value of hope cognitions would be dependent upon the quality of an individual's defense style. Undergraduate students completed measures of hope, defense mechanisms, and dysphoria in two studies. As predicted, defense mechanisms significantly moderated the relation between hope and dysphoria. In addition, both hope and defense mechanisms predicted dysphoria as main effects. Individuals who had low hope and an immature defense style had particularly high levels of dysphoria. Low hope was not maladaptive for individuals with a mature defense style, suggesting that a subtype of low hope ("defensive hopelessness") may exist that is analogous to defensive pessimism. Individuals with high hope had low levels of dysphoria regardless of defense style. Overall, the present study suggests that an integration of psychodynamic and cognitive perspectives on hope may be productive.

Adaptation, Psychological↗
PubMed1999

Attributional style and psychodynamic defense mechanisms: toward an integrative model of depression.

The present study examined the influences of cognitive style and psychodynamic defense mechanisms in accounting for levels of dysphoria. Measures of dysphoria, defense mechanisms, and attributional style were completed by 147 undergraduate students. Consistent with the hypothesis, both attributional style and principalization were independently associated with dysphoria. Moreover, principalization moderated the influence of attributional style on levels of dysphoria. In addition, attributional style and turning against self were independently associated with dysphoria. Turning against other, projection, and reversal were not associated with dysphoria. The results provide partial support for the notion that the applicability and validity of the hopelessness theory of depression are bolstered by a consideration of psychodynamic phenomena. Potential implications of this line of research for the movement toward psychotherapy integration are discussed.

Adolescent↗
PubMed1997

Dissociation of microglial activation and neuropathic pain behaviors following peripheral nerve injury in the rat.

Peripheral nerve injury commonly leads to neuropathic pain states fostered, in part, by neuroimmunologic events. We used two models of neuropathic pain (L5 spinal nerve cryoneurolysis (SPCN) and chronic constriction injury (CCI)) to assess the role of spinal glial activation responses in producing pain behaviors. Scoring of glial responses subjectively encompassed changes in cell morphology, cell density and intensity of immunoreactivity with specific activation markers (OX-42 and anti-glial fibrillary acidic protein (GFAP) for microglia and astrocytes, respectively). Glial responses were compared with tactile sensitivity (mechanical allodynia) at 1, 3 or 10 days following SPCN and with thermal hyperalgesia at 10 days in the CCI group. Neuropathic pain behaviors preceded and did not closely correlate with microglial responses in either model. Perineural application of bupivacaine prior to SPCN prevented spinal microglial responses but not pain behaviors. Spinal astrocytic responses to SPCN were early, robust and not altered by bupivacaine. The current findings support the use of bupivacaine as a tool to suppress microglial activation and challenge the putative role of microglia in initiating or potentiating pain behaviors which result from nerve injury.

Anesthetics, Local↗
PubMed1993

Life stress and dysphoria: the role of self-esteem and hopelessness.

This study evaluated the hypotheses that the relation between life stress (life events and daily hassles) and longitudinal change in dysphoria would be (a) moderated by self-esteem and (b) mediated by longitudinal change in hopelessness. Eighty undergraduates were first assessed on self-esteem, hopelessness, and dysphoria and then reassessed 3 months later on life events, daily hassles, hopelessness, and dysphoria. Residual change in dysphoria was significantly associated with self-esteem, life stress, and a Self-Esteem X Life Stress interaction. However, inconsonant with predictions, the moderating impact of self-esteem was greatest under conditions of low (vs. high) life stress. Moreover, residual change in hopelessness mediated the relations between residual change in dysphoria and both self-esteem and life stress.

Adolescent↗
PubMed1991

Developmental changes in memory source monitoring.

Previous research suggests that children are more likely than adults to confuse memories of actions they imagined themselves performing with memories of actions they actually performed (Realization Judgments), but are not more likely to confuse memories of actions they had imagined performing with memories of actions they saw another person perform (Reality Monitoring). We approach these findings in terms of a theory about the processes by which people identify the sources of their recollections (Source Monitoring). This approach suggests that children may be more likely than adults to confuse memories from different sources whenever the sources are highly similar to one another. Experiments 1 and 2 tested this hypothesis by manipulating the perceptual and semantic similarity of two sources of information and testing 4- and 6-year-old and adult subjects' recollection of the sources of particular pieces of information. Experiment 3 tested the hypothesis that children are more likely than adults to mistakenly identify memories of things they imagined another person doing as memories of things they witnessed that person doing. The findings indicate that (a) people are more likely to confuse memories from similar than dissimilar sources, (b) source monitoring improves during the preschool and childhood years, and (c) children may be especially vulnerable to the effects of source similarity.

Adult↗
PubMed1991

Long-term follow-up of the use of nonporous hydroxyapatite for augmentation of the alveolar ridge.

Particulate hydroxyapatite (HA) was used in the augmentation of 18 mandibular and four maxillary ridges in 21 patients whose cases were followed postoperatively for 5 to 7 years. Patients were evaluated clinically, radiographically, and through questionnaires. Prosthodontic assessment of retention and stability of dentures showed improvement 5 years postoperatively. Patients receiving HA rated their dentures favorably using parameters of the Cornell Medical Index. The results of this study show that particulate HA alone can be used as a satisfactory material for augmentation of the alveolar ridge.

Adult↗
PubMedDate not supplied

Aspirin enhances multidrug resistance gene 1 expression in human Molt-4 T lymphoma cells.

BACKGROUND: We recently found that aspirin induces the expression of P-glycoprotein (P-gp), a protein mediating drug resistance, in human prostate cancer cells. The purpose of this study was to evaluate the effect of aspirin on the expression of P-gp in a different human cancer type, i.e., T lymphoma. Furthermore, we analyzed this effect at the level of the gene encoding P-gp, MDR1, and of the transcription factor (NF-IL6), regulating this gene. MATERIALS AND METHODS: NF-IL6 was assayed by the electrophoretic mobility shift assay, MDR1 mRNA was assayed by the reverse transcriptase polymerase chain reaction (RT-PCR), and P-gp was assayed by Western blotting. RESULTS: aspirin, at plasma attainable levels, induced NF-IL6 DNA-binding activity, and increased MDR1 mRNA expression (by up to 140%), as well as the expression of P-gp, in Molt-4 cells. CONCLUSIONS: This study suggests that treatment with aspirin induces a cellular signal culminating in the enhancement of P-gp expression in T lymphoma Molt-4 cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗