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K Davidson

Publications and source records attributed to K Davidson.

At least 73 records · Page 4Linked to original sources
PubMed1996

Development and preliminary testing of a brief intervention for modifying CHD-predictive hostility components.

Hostility is an independent risk factor for coronary heart disease (CHD), and certain hostility subscales (e.g., Barefoot's refined Ho) predict CHD and mortality more powerfully than global hostility measures. An intervention for modifying CHD-predictive hostility components was developed and tested. Twenty-two healthy, high-hostile males, who were matched on age and hostility level, were randomly assigned to either an experimental hostility-reduction treatment group or an information-control group. The experimental group received eight 90-min weekly sessions for altering antagonism, cynicism, and anger reactions. After controlling for pretreatment levels, subjects' group status accounted for an additional and significant 28 and 19% of the variance in improvement of observed Anger-Out scores and Barefoot's refined Ho scores, respectively. Thus, this treatment may reduce CHD-predictive and mortality-predictive hostility levels. The possible clinical significance of these results was tested, and future large-scale and long-term trials are recommended.

Adult↗
PubMed1996

Coder gender and potential for hostility ratings.

This study examined the effects of coder gender on Potential for Hostility ratings. Six trained coders (3 men and 3 women) who were unaware of the coder gender effect hypothesis coded 30 male and 30 female undergraduates for Potential for Hostility. Although reliability estimates as calculated by Cronbach's alpha suggested that all coders were consistent, an analysis of variance revealed a significant main effect for coder gender, wherein female coders rated participants as displaying significantly less Potential for Hostility than did male coders. This significant difference was also meaningful, as coder gender accounted for 32% of the variance in Potential for Hostility scores. Thus, future Potential for Hostility investigations need to consider the gender of those coding, as this factor both significantly and substantially influences reported Potential for Hostility ratings.

Adult↗
PubMed1996

Reliability of an idiographic Q-sort measure of defense mechanisms.

Despite the important insights the concept of defense mechanisms may offer to our understanding of human behavior, no standardized definitions of defense mechanisms have been universally accepted. Inconsistencies in the definition and conceptualization of defense mechanisms has limited the practical utility of research involving these constructs. In addition, lack of interrater reliability, use of anecdotal evidence, and reliance on self-reports has retarded their investigation. Conducting methodologically rigorous investigations with a psychometrically sound instrument is the first step in addressing some of the issues concerning defense mechanisms and their theoretical postulates. This study was conducted to determine the reliability associated with the Defense-Q, an observer-based Q-sort measure of defense mechanisms. Thirty participants who had undergone an interpersonally stressful interview (the Type A Structured Interview; Rosenman, 1978) were rated by 11 trained coders, both for their use of the 25 defense mechanisms and for their ego strength. Reliability was assessed using Cronbach's alpha. Individual defense mechanisms demonstrated reliability ranging from .28 (undoing) to .92 (humor), with an average reliability of .73. Coder reliability ranged from .63 to .76, with an average of .69. These results indicate that defense mechanisms can be reliably assessed by the Defense-Q. Reliability of the Defense-Q is compared to existing observational measures of defense mechanisms.

Journal Article↗
PubMed1995

Novel cellulose-binding domains, NodB homologues and conserved modular architecture in xylanases from the aerobic soil bacteria Pseudomonas fluorescens subsp. cellulosa and Cellvibrio mixtus.

To test the hypothesis that selective pressure has led to the retention of cellulose-binding domains (CBDs) by hemicellulase enzymes from aerobic bacteria, four new xylanase (xyn) genes from two cellulolytic soil bacteria, Pseudomonas fluorescens subsp. cellulosa and Cellvibrio mixtus, have been isolated and sequenced. Pseudomonas genes xynE and xynF encoded modular xylanases (XYLE and XYLF) with predicted M(r) values of 68,600 and 65000 respectively. XYLE contained a glycosyl hydrolase family 11 catalytic domain at its N-terminus, followed by three other domains; the second of these exhibited sequence identity with NodB from rhizobia. The C-terminal domain (40 residues) exhibited significant sequence identity with a non-catalytic domain of previously unknown function, conserved in all the cellulases and one of the hemicellulases previously characterized from the pseudomonad, and was shown to function as a CBD when fused to the reporter protein glutathione-S-transferase. XYLF contained a C-terminal glycosyl hydrolase family 10 catalytic domain and a novel CBD at its N-terminus. C. mixtus genes xynA and xynB exhibited substantial sequence identity with xynE and xynF respectively, and encoded modular xylanases with the same molecular architecture and, by inference, the same functional properties. In the absence of extensive cross-hybridization between other multiple cel (cellulase) and xyn genes from P. fluorescens subsp. cellulosa and genomic DNA from C. mixtus, similarity between the two pairs of xylanases may indicate a recent transfer of genes between the two bacteria.

Amidohydrolases↗
PubMed1995

Dual-energy X-ray absorptiometry of the calcaneus: comparison with vertebral dual-energy X-ray absorptiometry and quantitative computed tomography.

The purpose of this study was to determine the efficacy of using bone mineral measurements of the calcaneus to evaluate osteoporosis. Dual energy X-ray absorptiometry (DXA) of the calcaneus was compared with posteroanterior lumbar absorptiometry (DXA) and vertebral quantitative computed tomography (QCT) measurements in 171 white women (78 normal and 93 osteoporotic). DXA measurement of os calcis mineralization decreased significantly in osteoporosis, but to a lesser extent than in vertebral sites. In normal subjects, good correlations were observed between calcaneal and lumbar DXA (0.69) and QCT (0.56). In subjects with vertebral fractures, there was also good correlation between calcaneal DXA and QCT (0.59-0.69). This suggests that trabecular bone in calcaneus and vertebrae have related involution in cases of vertebral osteoporosis. However, the extent of bone loss is less marked in the calcaneus than in the vertebrae and is not sufficient to be accurately measured over time. We conclude, therefore, that although the global densitometric measurement at this site is not sufficiently sensitive for general use, it can be useful as a epidemiological research tool.

Absorptiometry, Photon↗
PubMed1995

What does potential for hostility measure? Gender differences in the expression of hostility.

We examined the construct validity of Potential for Hostility (PH) for healthy undergraduate males and females. In Study 1, 45 males and 76 females were rated for PH. Subjects then completed the Cook Medley Hostility Scale (Ho) and a trait negative affectivity (NA) scale. For males, PH correlated with Cynicism, a subscale of the Ho, but was unrelated to NA. However, for females, PH was unrelated to self-reported hostility and minimally related to NA. In Study 2, 52 males and 91 females again were rated for PH in addition to state NA; subjects also provided self-reported state NA and PH measures. For males, convergence was found between observed and self-reported PH scores, but no such relation was found for females; only self-reported and observed state NA predicted females' PH rating. Thus, the Structured Interview method of hostility assessment may not be measuring the same hostility construct in females as it is in males.

Adolescent↗
PubMed1995

Comparison of BioStar Strep A OIA optical immune assay, Abbott TestPack Plus Strep A, and culture with selective media for diagnosis of group A streptococcal pharyngitis.

We directly compared three techniques for the diagnosis of group A streptococcal pharyngitis in 500 symptomatic children seen in the Emergency Department or Child Care Clinic of The Children's Hospital of Denver. Throats were vigorously swabbed with two rayon swabs, which were transported immediately to the Microbiology Laboratory. Each swab was cultured aerobically on Strep A Isolation Agar (Remel) and then tested for antigen-one swab by the Strep A OIA optical immune assay (BioStar) and the other by the TestPack Plus Strep A (Abbott) technique. Each test was performed blind to the others. The refrigerated pledget was cultured in Todd-Hewitt broth if an antigen test was positive and both direct plate cultures were negative (the "gold standard" was any culture positive). All isolates were serologically grouped. Of 500 complete patient cultures, 151 (30%) were positive for group A streptococcal growth. The two antigen tests gave comparable results with an average sensitivity of 83%. Each was significantly (P < 0.02) less sensitive than its corresponding culture. The BioStar Strep A OIA optical immune assay produced significantly (P < 0.003) more false-positive results than did the Abbott test. Rapid antigen testing is not sensitive enough to eliminate the need for backup cultures.

Antigens, Bacterial↗
PubMed1995

Patterns of improvement in depressive symptoms with fluoxetine treatment.

By definition, patients who respond to antidepressant treatment show significant improvements in most, if not all, of their depressive symptoms. We assessed the patterns of change in depressed outpatients treated openly with fluoxetine 20 mg/day for 8 weeks. We studied 62 depressed outpatients with major depressive disorder who showed full response following fluoxetine treatment. Analysis of the data revealed that the symptoms that tended to improve relatively early during treatment were suicidal ideation, excessive guilt, and lack of appetite. Our tentative conclusion from this pilot study was that symptom improvement tends to occur in both cognitive and neurovegetative areas early in treatment as well as later.

Adolescent↗
PubMed1993

Patellofemoral pain syndrome.

Patellofemoral pain syndrome is a common problem that occurs in association with mild malalignment of the extensor mechanism of the knee or as a result of repetitive microtrauma from overuse. Patients most often present with retropatellar or peripatellar knee pain, which becomes especially noticeable when they climb or descend stairs. The diagnosis is usually made from the history and the physical examination, with relatively little information gained from other diagnostic aids. Treatment involves physical therapy, anti-inflammatory medication and the application of ice. In most patients, surgical treatment should be avoided. Patient motivation and adherence to the treatment regimen are critical to long-lasting improvement.

Biomechanical Phenomena↗
PubMed1993

Neuronal vs. glial somatostatin in the hypothalamus: a cell culture study of the ontogenesis of cellular location, content and release.

Somatostatin (SRIH) is an ubiquitous peptide subserving functions as a hypothalamic-hypophysial regulatory peptide and as a neuromodulator in the CNS, as well as various roles in the periphery. Based on our earlier observations that the ability of primary cultures of foetal rat hypothalamic cells to secrete SRIH developed distinct differences depending on whether they were maintained in a serum-supplemented medium (SSM) or a defined, serum free medium (DM), coupled with recent reports that glia in several brain regions may express neuropeptides, we have investigated the cellular location of SRIH in these cultures. Using immunocytochemical techniques (ICC) for the simultaneous location of SRIH and glial fibrillary acidic protein (GFAP) we found that SRIH-like immunoreactivity (SRIH-LI) was present in a significant number of hypothalamic glial cells around the time of birth. In the presence of serum, this expression persists and even by day 9 in culture a dense and intense immunofluorescent SRIH-LI signal was observed in GFAP positive cells. However, in DM glial expression is switched off rapidly (although GFAP positive cells are still present) until SRIH-LI eventually occurs at a much reduced abundance in GFAP negative neuronal cell types. In addition, the SRIH content of SSM cultures was three-fold greater than that from SSM cultures. Thus our results indicate that the mechanisms for SRIH-LI release from astrocytes appears to be distinctly different to that from neuronal-type cells. We propose that glial cell expression of SRIH-LI may represent a developmentally important phenomenon in the hypothalamus, e.g. serving a trophic role during critical times of development, and that its expression in glia may be stimulated by factors present in serum. Consequently, an understanding of factors which regulate SRIH expression and release from glia is likely to be of importance to our understanding of brain development, injury, repair and diseases of the CNS.

Animals↗
PubMed1993

Tobacco smoking.

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Humans↗
PubMed1993

Vitamin K1 metabolism and the production of des-carboxy prothrombin and protein C in the term and premature neonate.

This study investigated the incidences of undercarboxylated (protein induced by vitamin K absence: PIVKA) prothrombin and protein C in 496 neonates across a wide range of gestational ages. These findings are related to vitamin K1 levels (an indicator of cofactor availability) and vitamin K1 epoxide levels (a measure of the efficiency of the hepatic vitamin K cycle). PIVKA protein C was present in at least trace amounts in 27% of infants; whereas, PIVKA prothrombin was present in 7% of infants. PIVKA prothrombin and protein C were present at high plasma concentrations in 2% to 3% of term and preterm neonates and both PIVKA protein C and prothrombin increased with gestational age. Despite elevated plasma concentrations of PIVKA protein C and diminished levels of normally carboxylated protein C, clinical thrombosis was not observed. The mean (+/- SD) vitamin K1 level in the study population was 0.009 +/- 0.02 nmol/L (adult reference interval: 0.3 to 2.6 nmol/L) with no clear relationship between vitamin K1 levels and production of PIVKA protein C or prothrombin. By comparison with adults, the epoxide form of the vitamin comprised an abnormally high proportion of total vitamin K1; this suggests possible inefficiencies in hepatic reductase cycling.

Biomarkers↗
PubMed1993

Gene sequence and properties of CelI, a family E endoglucanase from Clostridium thermocellum.

The Clostridium thermocellum celI gene, coding for endoglucanase I (CelI), consists of an open reading frame (ORF) of 2640 nucleotides and codes for a protein of M(r) 98531. The ORF was confirmed as celI by comparing the N-terminal sequence of purified recombinant CelI with that deduced from the nucleotide sequence. CelI hydrolysed lichenan and carboxymethylcellulose, but was principally active against barley beta-glucan. It exhibited significant sequence identity with subfamily E2 endoglucanases, and by analogy with others in this group contains a catalytic domain of around 500 residues located in the N-terminal half of the protein. The C-terminal region of CelI was highly homologous with the cellulose-binding domain of the non-catalytic cellulosome subunit, S1. A repeated segment, previously shown to be highly conserved in xylanase Z and in other endoglucanases from C. thermocellum, was absent from CelI. Antiserum raised against purified recombinant CelI cross-reacted with proteins contained in the cellulosomes of two strains of C. thermocellu, suggesting that CelI is either a component of the cellulosome or is homologous to other cellulosome proteins. A second gene, located upstream of celI, consisted of an ORF of 1671 nucleotides, coding for a protein of M(r) 61042. Based on its homology with the Escherichia coli tar gene product, the polypeptide encoded by the second gene is tentatively identified as a sensory transducer.

Amino Acid Sequence↗
PubMed1992

Assessment of a rapid latex agglutination test for group B streptococcal colonization of the genital tract.

OBJECTIVE: The purpose of this study was to determine the reliability of a rapid enzyme extraction-latex agglutination test in detecting intrapartum colonization of the maternal genital tract by group B streptococci. METHODS: Swabs of vaginal secretions were obtained from 314 patients in labor with either ruptured or intact membranes. Four tests were performed on each specimen: 1) qualitative culture on blood agar, 2) semiquantitative culture on blood agar, 3) culture in selective Todd-Hewitt broth, and 4) latex agglutination preceded by enzyme extraction. RESULTS: The prevalence of positive cultures was 29%. When compared with culture in Todd-Hewitt broth, the latex agglutination test had a sensitivity of 30%, specificity 93%, positive predictive value 64%, and negative predictive value 76%. In patients with heavy colonization the test had a sensitivity of 76%, compared with 17% in patients with light growth (P less than .001). The lower limit of sensitivity of the test was 4 x 10(5) cfu/mL. The performance of the test was not affected by rupture of the membranes. CONCLUSION: Although the latex agglutination test is reasonably sensitive in detecting heavy colonization, low overall performance combined with technical difficulties in assessment of particle agglutination make the test unsuitable for general screening.

Evaluation Studies as Topic↗
PubMed1992

A case of multiple endocrine neoplasia: hyperparathyroidism, insulinoma, GRF-oma, hypercalcitoninaemia and intractable peptic ulceration.

A 42-year-old woman with a family history of multiple endocrine neoplasia type 1 (MEN 1) presented with symptomatic hypoglycaemia and peptic ulceration. Investigation revealed an insulinoma, hyperparathyroidism, hypercalcitoninaemia with a positive pentagastrin stimulation test, acromegaly due to a GRF-oma, hyperprolactinaemia and normal serum gastrin levels. Five pancreatic tumours were removed at laparotomy and immunostaining was positive for insulin, calcitonin, somatostatin and glucagon. Post-operatively she developed elevated serum gastrin levels and gross peptic ulceration, despite H2-blockers, and died of gastro-intestinal haemorrhage suggesting that removal of the somatostatinoma may have allowed increased gastrin secretion from a gastrinoma. This case emphasizes the importance of measuring a wide variety of tumour marker peptides in MEN 1 and suggests that caution is required in interpretation of the pentagastrin stimulation test in such cases. Patients with MEN 1 and known peptic ulceration may require perioperative omeprazole treatment even if serum gastrin levels are normal.

Adenoma↗
PubMed1992

GABAergic influences on somatostatin secretion from hypothalamic neurons cultured in defined medium.

The effects of GABAergic influences intrinsic to the hypothalamus on the secretion of somatostatin were studied using cultured fetal rat hypothalamic neurons. The existence of GABAergic neurons within the cultures was confirmed by immunocytochemistry. These neurons appeared to be actively secreting GABA as antagonism of GABAA receptors with bicuculline and picrotoxinin caused a dose-dependent increase in the release of immunoreactive somatostatin (SRIF), which was Ca(2+)-dependent. Although exogenous GABA inhibited SRIF secretion at concentrations of 10(-6) M and greater, muscimol, a GABAA agonist, inhibited SRIF release at 10(-8) M, whereas baclofen, a GABAB agonist, required concentrations two orders of magnitude greater to produce an effect. Phaclofen, a GABAB antagonist, was inactive (10(-8)-10(-4) M). A GABA uptake inhibitor, SKF 89976A, produced a dose-dependent inhibition of SRIF release. These results, therefore, support a role for intrahypothalamic GABA neurons in the regulation of SRIF secretion in the neonatal rat, predominantly via a type A receptor, and provide further evidence for a neuroendocrine role for GABA in controlling growth hormone secretion.

Animals↗
PubMed1992

Preclinical leads for innovative uses for etoposide.

Amplification of oncogenes in human tumors has been associated with a poor prognosis. Microscopically visible amplified oncogenes can be located either within chromosomes in homogeneously staining regions, or in an extrachromosomal compartment in double minutes (DMs). The DMs are composed of submicroscopic circular DNA (episomes), which have multimerized to form the microscopically visible DMs. When amplified oncogenes are located in an extrachromosomal location, they are vulnerable to loss from the cell. In this study we have found that the topoisomerase II inhibitor etoposide, in concentrations easily achievable clinically, causes a significant decrease in the number of DM-containing amplified oncogenes in three different human tumor cell lines. The elimination of amplified oncogenes from the cell could be accompanied by less aggressive tumor behavior.

DNA, Circular↗