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Biomedical subjects

D Locker

Publications and source records attributed to D Locker.

At least 55 records · Page 3Linked to original sources
PubMed2000

Changes in levels of dental anxiety as a function of dental experience.

From the literature, it is increasingly apparent that dentally anxious individuals are not a homogeneous group and that the development and maintenance of dental anxiety are complex phenomena. In this study, individuals who had avoided dental treatment in the past due to fear but were no longer fearful were compared with others who had avoided and were still fearful on a number of demographic, experiential, and attitudinal variables under the assumption that avoidance is likely to prevent the emotional processing of dental anxiety. The groups differed markedly in their experience of dentistry; anxious avoiders were more likely to have experienced more invasive and less noninvasive dental treatment; they feared pain more and were more negative about dentistry than those whose anxiety had remitted. In addition, the remitted avoiders were less likely to claim frightening or embarrassing dental experiences as well as being less reactive to these experiences than the others.

Adaptation, Psychological↗
PubMed1999

Diagnostic categories of dental anxiety: a population-based study.

This study aimed to use a population-based sample to assess the psychological validity of the Seattle system for diagnosing dentally anxious individuals. This system consists of four diagnostic types in which such individuals are categorized according to the main source of their fear regarding dental treatment. Subjects were 1420 randomly selected adults aged 18 years and over who took part in a two-stage mail survey. The questionnaires contained measures of dental anxiety and standardized measures of general anxiety and fearfulness. Allocation to the Seattle categories was based on responses to four diagnostic items. Overall, 16.4% of the sample were dentally anxious. Their distribution across the four Seattle types was as follows: type I (simple conditioned phobia)--49.6%; type II (fear of catastrophe)--7.8%; type III (generalized anxiety)--19.4% and type IV (distrust of dentists)--9.9%. The remaining 13.3% could not be categorized. Judging by their scores on measures of dental anxiety, these subjects were borderline cases. Scores on the measures of anxiety and fearfulness indicated that the diagnostic system was valid and identified sub-groups of the dentally anxious population which were internally consistent. However, all subjects indicated extreme fear of dental treatment and were broadly similar in terms of their cognitive and behavioral responses to dental care. Of particular interest was the distribution of diagnoses according to age. Younger subjects were more likely to be categorized as type I, while older subjects were more likely to be categorized as type III. Overall, the results indicate that dental anxiety is a complex fear with a number of components.

Adolescent↗
PubMed1999

In vitro and in vivo antitumour activity and cellular pharmacological properties of new platinum-iminoether complexes with different configuration at the iminoether ligands.

In order to widen our knowledge on antitumour trans-[PtCl2(iminoether)2] complexes, we have synthesised two new derivatives, trans-[PtCl2¿E-HN = C(OEt)Me¿2] (1) and trans-[PtCl2¿Z-HN = C(OEt)Me¿2] (2), which differ in the configuration of the iminoether ligands. Isomer 1 showed an in vitro cytotoxicity similar to that of cisplatin in a panel of human tumour cell lines (mean IC50 = 8 and 7.7 microM, respectively), whereas isomer 2 showed a lower activity (IC50 = 14.3 microM). Both 1 and 2 isomers overcame cisplatin resistance of ovarian cancer cell line A2780/Cp8. In agreement with the n-octanol/saline partition ratios, intracellular platinum content (and DNA platination) after a 2-h exposure to equimolar drug concentrations was in the order 1 > 2 >> cisplatin, thus indicating that substitution of imminoethers for ammines determines a major lipophilicity and cellular uptake of the platinum drug. Both 1 and 2 showed a major toxic effect towards an excision repair-defective Drosophila strain, thus indicating cellular DNA as cytotoxic target. Finally, both 1 and 2 were active in vivo against the murine P388 system, but, contrary to the in vitro activity, isomer 2 was slightly more active than 1. On the whole, the results confirm the antitumour activity of trans-[PtCl2(iminoether)2] complexes, and indicate that the configuration of the iminoether ligands may affect the pharmacological properties of this class of complexes.

Animals↗
PubMed1999

The relationship between dental status and health-related quality of life in upper aerodigestive tract cancer patients.

Although the oral sequelae of treatments for upper aerodigestive tract (UADT) cancers have been well described, very little is known about the relationship between dental status and health-related quality of life (HRQL) in patients with UADT cancer. The aim of this study was to investigate the hypothesis that dental status is a predictor of HRQL in a sample of post-therapeutic UADT cancer patients. A cross-sectional study design was used with a sample of 188 subjects. HRQL was evaluated through the global domain of the EORTC QLQ-C30 instrument and data were collected on sociodemographic, disease, treatment and dental status variables. Linear multiple regression analysis was used to determine those variables with a significant independent association with the HRQL. Two multivariate models were developed each containing age, gender, employment status, cancer site and disease stage, plus either the dental status category "partially dentate with no prosthesis" (P/NP) (F-value for model = 7.31; P < 0.0001; r2 = 0.20) which predicted a significantly worse HRQL, or the dental status category "edentulous with prostheses" (E/WP) (F-value for model = 7.56; P < 0.0001; r2 = 0.20) which predicted a significantly better HRQL. Furthermore, the P/NP group reported significantly more "problems with their teeth" (ANOVA, P = 0.0004), significantly more "trouble eating" (ANOVA, P = 0.024) and significantly more "trouble enjoying their meals" (ANOVA, P = 0.01). Although the cross-sectional nature of the data collection and the somewhat crude nature of the dental status variable limit inferences, the results of this study suggest that dental status has an important effect on HRQL in post-therapeutic UADT cancer patients.

Adult↗
PubMed1999

Domain-domain interactions in high mobility group 1 protein (HMG1).

The high mobility group protein HMG1 is a conserved chromosomal protein with two homologous DNA-binding domains, A and B, and an acidic carboxy-terminal tail, C. The structure of isolated domains A and B has been previously determined by NMR, but the interactions of the different domains within the complete protein were unknown. By means of differential scanning calorimetry and circular dichroism we have investigated the thermal stability of HMG1, of the truncated protein A-B (HMG1 without the acidic tail C) and of the isolated domains A and B. In 3 mm sodium acetate buffer, pH 5, the thermal melting of domains A and B are identical (transition temperature tm = 43 degrees C and 41 degrees C, denaturation enthalpies DeltaH = 46 kcal.mol-1). The thermal melting of protein A-B presents two nearly identical transitions (tm = 40 degrees C and 41 degrees C, DeltaH = 44 kcal.mol-1 and 46 kcal.mol-1, respectively). We conclude that the two domains A and B within protein A-B behave as independent domains. The thermal melting of HMG1 is biphasic. The two transitions have a different value of tm (38 degrees C and 55 degrees C) and corresponding values of DeltaH around 40 kcal.mol-1. We conclude that within HMG1, the acidic tail C is interacting with one of the two domains A and B, however, the two domains A and B do not interact with each other. At 37 degrees C, one of the two domains A and B, within HMG1, is partly unfolded, whereas the other which interacts with the acidic tail C, is fully native. The interaction free energy of the acidic tail C is estimated to be in the range of 2.5 kcal.mol-1 based on simulations of the thermograms of HMG1 as a function of the interaction free energy.

Calorimetry, Differential Scanning↗
PubMed1999

Geographic variations in dental services provided to older adults in Ontario, Canada.

In an initial study, Leake et al. (J Public Health Dent 1996; 52: 182-90) found that older Ontarians living in metropolitan communities received almost twice the amount of dental care than older Ontarians living in non-metropolitan communities. Since data were collected for the 2 years prior to the enrollment of subjects in a longitudinal study, factors responsible for this variation could not be explored. This paper extends these findings by examining the volume of dental services received by these subjects in the 3 years between the baseline and follow-up phases of the longitudinal study. During this 3-year period, geographic variations in the volume of services provided were also observed. In a regression analysis, geographic location remained a significant predictor of the number of services received after controlling for six other explanatory variables: insurance coverage, number of teeth, restorative treatment need, self-rated oral health, regular dental visits and use of specialist services. Together, these explained only 24% of the variance in service provision. Since patient-reported outcomes were better in the communities with higher volumes of provision, further research concerning the patient and dentist factors influencing treatment provision is warranted.

Aged↗
PubMed1999

A comparison of the validity of generic- and disease-specific measures in the assessment of oral health-related quality of life.

UNLABELLED: In recent years, a number of instruments have been developed to measure the outcomes of oral disease. The Oral Health Impact Profile (OHIP) is the most sophisticated and comprehensive measure developed to date. At present, reports of the use of this measure are confined to descriptive population studies. OBJECTIVES: The aim of this study was to compare the validity of the OHIP with a generic health-related quality of life measure, the SF36. METHODS: Study subjects were in three groups, namely, edentulous patients seeking dental implants ("implant subjects", n = 32), edentulous patients seeking conventional dentures ("edentulous control", n = 35) and dentate patients ("dentate control", n = 21). All subjects completed an OHIP and SF36 prior to receiving any treatment. The edentulous subjects also completed a subjective assessment of satisfaction with their existing conventional dentures. OHIP data were computed using the simple count and weighted scores methods. RESULTS: The median number of negative impacts reported for each group was: 17 (implant subjects), six (conventional control) and one (dentate control). OHIP sub-scale scores were significantly higher (P < 0.001) for implant subjects than control subjects. There were no significant differences between the SF36 sub-scale scores. There was a significant correlation (P < or = 0.01) between aspects of satisfaction with conventional dentures worn by the edentulous subjects and OHIP sub-scale scores. Correlations between denture satisfaction variables and SF36 scores were not significant. CONCLUSIONS: It was concluded that the OHIP shows good discriminant and construct validity properties. As it is oral specific, it will be of greater use in measuring outcomes of oral disorders than generic measures such as SF36. This finding will be relevant when considering the use of health-related quality of life measures to target resources and measure the outcome of clinical intervention.

Adult↗
PubMed1999

A cross-cultural study of oral health values.

The Oral Health Impact Profile (OHIP) is a measure of oral-health-related quality of life developed in Australia but being used increasingly in other populations. In view of the culturally specific nature of peoples' perceptions of health, if we are to make between-population comparisons of oral-health-related quality of life, cross-cultural equivalency of the relevant instruments needs to be verified. A study was therefore undertaken to compare item weights generated by an Australian sample with those generated by a sample of English-speaking Canadians and another of French-speaking Canadians. In addition, within-group comparisons by age were performed. The items and subscales used for the 2 Canadian samples were identical to those developed in Australia, although a formal French translation was used for the French-speaking sample. The method used for the generation of weights was Thurstone's paired-comparison technique, based on the judgments of convenience samples of subjects drawn from each of the three cultural settings. Comparisons were made by means of intra-subscale weight rankings and magnitude. Spearman's rank correlations of r> or =0.6 were found for 16/21 between-group comparisons and for 12/21, 19/21, and 8/21 within-group comparisons made by age in Australia, Ontario, and Quebec, respectively. Comparisons of the magnitudes of weights found that, even when items were ranked similarly, magnitudes could be quite different. These results suggest a reasonable degree of cross-cultural consistency, and hence validity, for the OHIP.

Adolescent↗
PubMed1999

Age of onset of dental anxiety.

Little attention has been given to the issue of the age of onset of dental anxiety, even though it may have a bearing on the origins of this type of fear. This study aimed to identify the age of onset of dental anxiety and to identify differences by age of onset with respect to potential etiological factors, such as negative dental experiences, family history of dental anxiety, and general psychological states. Data were collected by means of two mail surveys of a random sample of the adult population. Of 1420 subjects returning questionnaires, 16.4% were dentally anxious. Half, 50.9%, reported onset in childhood, 22.0% in adolescence, and 27.1% in adulthood. Logistic regression analyses indicated that negative dental experiences were predictive of dental fear regardless of age of onset. A family history of dental anxiety was predictive of child onset only. Adolescent-onset subjects were characterized by trait anxiety and adult-onset subjects by multiple severe fears and symptoms indicative of psychiatric problems. The three groups were similar in terms of their physiological, cognitive, and behavioral responses to dental treatment. However, adolescent- and adult-onset subjects were more hostile toward and less trusting of dentists. These results indicate that child-onset subjects were more likely to fall into the exogenous etiological category suggested by Weiner and Sheehan (1990), while adult-onset subjects were more likely to fall into the endogenous category.

Adolescent↗
PubMed1999

Cytotoxicity and DNA binding mode of new platinum-iminoether derivatives with different configuration at the iminoether ligands.

The platinum-iminoether complexes trans-[PtCl2[E - HN = C(OEt)Me]2] (1) and trans-[PtCl2[Z - HN = C(OEt)Me[2] (2), differing in the configuration of the iminoether ligands, were investigated for cytotoxicity towards human tumor cell lines, the involvement of DNA as a cytotoxic target, and their DNA binding mode. The cytotoxicity of isomer 1 was comparable to that of cisplatin, whereas isomer 2 was slightly less active. Excision-repair-deficient xeroderma pigmentosum group A cells were four times more sensitive to both isomers than normal cells, thus implicating cellular DNA as the cytotoxic target. Replication mapping experiments showed that both isomers interact preferentially with guanine residues at py-G-py sites. Oligodeoxyribonucleotides containing unique N7-guanine monofunctional adducts of the more cytotoxic isomer 1 were prepared and investigated for chemical reactivity, stability and DNA conformational alterations. The results showed that the ability of thiourea to labilize the monofunctional adducts depends upon the DNA secondary structure, but not upon the sequence context. Monofunctional adducts evolve to bidentate adducts in single-stranded oligonucleotides, but they are stable in double-stranded oligonucleotides and produce conformational distortions selectively located at the 5'-adjacent base pair. This study gives new insight into the mechanism of action of trans platinum-iminoether complexes, enabling for the first time comparison between different ligand isomers.

Antineoplastic Agents↗
PubMed1999

Oral health promotion and caries prevention.

This paper is based on a paper presented at a British Dental Association caries prevention symposium. It represents the views of the authors and does not necessarily represent the views of any organisation with which they, or the work reported, are associated.

Dental Caries↗
PubMed1999

Dental insurance and use of dental services.

OBJECTIVES: This article examines socioeconomic differences in insurance for dental services among Canadians aged 15 or older and factors associated with the use of dental services. DATA SOURCE: The data on dental insurance coverage and use of dental services are from the cross-sectional file of Statistics Canada's 1996/97 National Population Health Survey. The sample size of respondents aged 15 or older was 70,884. ANALYTICAL TECHNIQUES: Logistic regression analysis was used to model variables related to dental insurance coverage and to dental visits in the past year. A weighted bootstrap resampling procedure was used to derive variance estimates. MAIN RESULTS: In 1996/97, 53% of the population aged 15 or older reported having dental insurance, and 59% said they had visited a dentist in the past year. But even when they had insurance, individuals with low incomes and low educational attainment had much lower odds of visiting a dentist than those with higher incomes and more education.

Adolescent↗
PubMed1998

DSP1 gene of Drosophila melanogaster encodes an HMG-domain protein that plays multiple roles in development.

DSP1 is an HMG-box containing protein of Drosophila melanogaster which was first identified as a co-repressor of the Dorsal protein. Recently, the analysis of the structure of the gene has led us to propose that DSP1 is the Drosophila equivalent of the ubiquitous vertebrate HMG 1/2 proteins. In the present paper, the patterns of expression of DSP1 protein and RNA in adult flies and during development are reported. In the adults DSP1 protein is located in nurse cells of ovaries and in brain. During eggs development uniform expression of DSP1 protein persists until the end of germband retraction. At later stages, expression is restricted to the ventral nerve chord and brain. Using P-element mutagenesis, we have isolated a mutant deficient in DSP1 functions. Genetic studies of this mutant show that DSP1 protein is essential for the growth and the development of Drosophila. In addition to be a co-repressor of the transcriptional activator Dorsal our results provide compelling evidence that DSP1 is a regulator involved in several pathways necessary for the development of the fly.

Animals↗
PubMed1998

Correlates of health-related quality of life in upper aerodigestive tract cancer patients.

Reflecting a limited understanding of the definition and determinants of health-related quality of life (HRQoL), the majority of research in this field has concentrated upon the effect of disease- and treatment-related variables. That work specifically investigating HRQoL among upper aerodigestive tract (UADT) cancer patients is no exception to this observation. Treating subject-related and non-subject-related variables separately, the aim of this study was to investigate predictors of global HRQoL rating in a sample of UADT cancer patients, concentrating upon the relative importance of sociodemographic and clinical variables. A cross-sectional study design was used with a sample of 188 UADT cancer patients. Global HRQoL was assessed using the EORTC QLQ-C30 instrument, global domain (global QoL). Other study variables were collected by subject interview and chart review. Two multivariate regression models were independently developed, containing, respectively, subject-rated and non-subject rated variables. In the model containing subject-rated predictors of global QoL, emotional, breathing, physical, financial, pain and appetite problems were significant predictors (F = 14.6, p < 0.0001 and r2 = 0.54). Among non-subject-rated sociodemographic and clinical variables tested, unemployment, older age, female gender, being dentate and a more advanced disease stage predicted worse global QoL rating, while oral as opposed to pharyngeal or laryngeal cancer predicted a better global QoL rating (F = 5.1, p < 0.0001 and r2 = 0.21). In the latter model, a greater proportion of the variance was explained by sociodemographic variables than by clinical variables.

Adult↗
PubMed1998

Issues in measuring change in self-perceived oral health status.

An important goal of a health care intervention or system is to improve the health of an individual or a population. The challenge for health services research is to measure and explain this change. However, the issue of how changes in health status should be defined and measured has been given relatively little attention. This paper draws on the rather sparse literature to examine some issues involved in measuring changes in oral health status and illustrates these using data from a longitudinal study of the oral health of older adults. The paper draws a distinction between quantitative and qualitative change and the challenges involved with each. Four different ways of assessing change are reviewed and their strengths and weaknesses highlighted. Global transition judgements, although relatively simple measures of change, incorporate patients' values and avoid the statistical problems associated with measures such as change scores. Nevertheless, the measurement of change in oral health status is complex and controversial and no approach is universally accepted. Consequently, the decision as to which strategy to adopt is far from simple.

Aged↗
PubMed1998

Oral health status of Canadian-born and immigrant adolescents in North York, Ontario.

Studies from a number of countries, including Canada, have demonstrated that the oral health status of immigrants is worse than that of their native-born counterparts and that they make less use of dental services. To date, however, little information is available which documents changes in immigrant oral health following immigration. This paper reports the results of a study conducted in the City of North York, Ontario, that examined the oral health status of Canadian-born and immigrant adolescents aged 13 and 14 years. The former had better oral health than the latter on all parameters assessed and made more use of dental services. Within the immigrant population, there was a significant association between oral health and time since immigration. Those who had been in Canada 6 or more years were significantly healthier than those who had arrived within the preceding 2 years. While changing patterns of immigration may account for part of these differences, the data suggest that access to dental public health programs, delivered to students between the ages of 4 and 14 years, have been effective in improving the oral health of those born outside Canada. Since these programs cease at age 13 or 14 years, barriers to accessing the private dental care sector may mean that the residual inequities and inequalities evident in the data widen as these individuals age.

Adolescent↗