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PubMed1996

Assessing the stages of pain processing: a multivariate analytical approach.

A four-stage model of pain processing was proposed, consisting of pain sensation intensity, pain unpleasantness (stage 1 affect), suffering (stage 2 affect), and pain behavior. We studied 506 chronic pain patients (230 male and 276 female) using a multivariate statistical technique (LISREL) in order to demonstrate the structural relationship among multiple indicators of pain processing; and to characterize these stages in terms of their interactions. A strong relationship was revealed between the majority of the underlying indicators of each pain processing stage. A linear stage sequence best fitted the relationship between the four stages. Successive stages did not have recursive effects on earlier pain components. A confirmatory LISREL analysis was conducted with an additional sample of 502 chronic pain patients. In this replication analysis the structural equation model consisted of pain intensity, unpleasantness (stage 1 affect), emotional suffering (stage 2 affect), and pain behavior. This study extends the validation of these pain dimensions, as well as the validity of the measure(s) of each separate stage.

Adolescent↗
PubMed1996

Stress distribution in the temporomandibular joint produced by orthopedic chincup forces applied in varying directions: a three-dimensional analytic approach with the finite element method.

Stress distribution in the temporomandibular joint (TMJ) during chincup therapy was investigated by means of a three-dimensional finite element model of the mandible, including the TMJ. An orthopedic chincup force of 400 gf (3.92 N) was applied at the pogonion of the mandible in the directions ranging from -50 degrees to 40 degrees, relative to the line connecting the pogonion and condyle. Compressive stresses, widely distributed on the condyle and glenoid fossa and in the articular disk, were larger in the posterior area than in the anterior and middle regions, when the force direction was from -50 degrees to 0 degree, whereas the forces applied in the remaining directions produced relatively uniform stress distributions. An interesting finding was that tensile stresses were induced in the anterior region of the articular disk, irrespective of force direction, although the remaining areas experienced compressive stresses. It is shown that changes in stresses in the TMJ are highly pertinent to the direction of chincup forces. When the directional angle was around -50 degrees, the variation in stresses in the TMJ was greatest. As the angle was changed to 30 degrees or 40 degrees, the stresses approached a certain level of compressive stress, which indicated the force direction as an optimal application of orothopedic chincup force in terms of biomechanically balanced stress distribution for the TMJ components.

Chin↗
PubMed1999

Hospital mortality from acute myocardial infarction has been modestly reduced after introduction of thrombolytics and aspirin: results from a new analytical approach. European Secondary Prevention Study Group.

The objective of this study was to investigate how the introduction of thrombolytics and aspirin has affected hospital mortality (case fatality) among patients with acute myocardial infarction. The study design was the application of the therapeutic effects found in the clinical trials in a nonselected myocardial infarction population characterized in detail. The study took place in health region 1 in Norway, population 850,000, and subjects were all patients hospitalized and discharged, alive or dead, with a diagnosis of acute myocardial infarction in the 10 hospitals in the region over a period of 2 months. The main outcome measures were deaths in hospital and estimation of expected hospital mortality without thrombolytics or aspirin, weighing and evaluating the effects of delay of different lengths from onset of symptoms to admission, different ages, and different electrocardiogram changes. We found that 32% of the patients received thrombolytics, and 72% received aspirin. Hospital mortality was 18.1% compared with 20.6% had neither of the treatments been administered, implying that the two regimens had reduced mortality by 12%, aspirin contributing about four fifths and thrombolytics one fifth. We conclude that hospital mortality in a nonselected myocardial infarction population has been reduced to moderate extent since the introduction of thrombolytics and aspirin. The effects observed in clinical trials are not translated into epidemiologically documented reduction in mortality, as the optimal conditions are found only in a proportion of the patient groups constituting a nonselected myocardial infarction population.

Aged↗
PubMed2004

Detection of causal relationships between factors influencing adverse side-effects from anaesthesia and convalescence following surgery: a path analytical approach.

BACKGROUND AND OBJECTIVE: The anaesthesiologist's preoperative interview with the patient is important in preparing the patient for surgery. Its potential protective influence on adverse side-effects from anaesthesia and convalescence is rarely investigated within the context of other perioperative factors. Structural equation modelling allows detection and quantification of all causal relationships and mediator effects in multivariate models. Therefore, this method is presented as a tool and applied to discover the influence of the preoperative interview within socio-demographic variables and duration of surgery on complaints and recovery after anaesthesia. METHODS: The influence of individual satisfaction with the anaesthesiologist's preoperative interview on postoperative events such as nausea/vomiting, difficulties in recovering from anaesthesia, experience of postoperative pain, physical discomfort and satisfaction with convalescence expressed by the patient was analysed by means of structural equation modelling. The variables gender, age and duration of surgery were also included as predictors in the analyses. The model in the total sample of 710 patients was then analysed for structural differences between groups treated either with propofol (n = 204) or with isoflurane + nitrous oxide (n = 267) for maintenance of anaesthesia. RESULTS: The model revealed that the anaesthesiologist's preoperative interview in combination with associated mediating side-effects explains 45% of the variance of 'feeling physical discomfort' and 18% of the variance of 'satisfaction with convalescence'. The same model could be fitted in the propofol and the isoflurane + nitrous oxide group. Moreover, the structure and the strength of causal relations between variables were identical in the two groups. CONCLUSIONS: The anaesthesiologist's efforts to improve the interview with the patient by more reassuring and proper information will result in less side-effects from anaesthesia and better recovery from surgery. It could be demonstrated that structural equation modelling is a powerful tool for detection of causal relationships and mediator effects in perioperative medicine.

Adolescent↗
PubMed2004

A novel analytical approach for visualizing and tracking organic chemicals in plants.

Vegetation plays a key role in the environmental fate of many organic chemicals, from pesticides applied to plants, to the air-vegetation exchange and global cycling of atmospheric organic contaminants. Our ability to locate such compounds in plants has traditionally relied on inferences being made from destructive chemical extraction techniques or methods with potential artifacts. Here, for the first time, two-photon excitation microscopy (TPEM) is coupled with plant autofluorescence to visualize and track trace levels of an organic contaminant in living plant tissue, without any form of sample modification or manipulation. Anthracene-a polynuclear aromatic hydrocarbon (PAH)-was selected for study in living maize (Zea mays) leaves. Anthracene was tracked over 96 h, where amounts as low as approximately 0.1-10 pg were visible, as it moved through the epicuticular wax and plant cuticle, and was observed reaching the cytoplasm of the epidermal cells. By this stage, anthracene was identifiable in five separate locations within the leaf: (1) as a thin (approximately 5 microm) diffuse layer, in the upper surface of the epicuticular wax; (2) as thick (approximately 28 microm) diffuse bands extending from the epicuticular wax through the cuticle, to the cell walls of the epidermal cells; (3) on the external surface of epidermal cell walls; (4) on the internal surface of epidermal cell walls; and (5) within the cytoplasm of the epidermal cells. This technique provides a powerful nonintrusive tool for visualizing and tracking the movement, storage locations, and degradation of organic chemicals within vegetation using only plant and compound autofluorescence. Many other applications are envisaged for TPEM, in visualizing organic chemicals within different matrixes.

Air Pollutants↗
PubMed2000

NMR analytical approach to clarify the molecular mechanisms of the antioxidative and radical-scavenging activities of antioxidants in tea using 1,1-diphenyl-2-picrylhydrazyl.

(+)-catechin, ethyl gallate, ascorbic acid, and alpha-tocopherol were reacted with 1,1-diphenyl-2-picrylhydrazyl (DPPH), and the reaction mixtures were subjected to 13C-nuclear magnetic resonance (NMR) analyses to clarify the molecular mechanisms of the antioxidative and radical-scavenging activities of each antioxidant. When ascorbic acid was reacted with DPPH, it was oxidized to dehydroascorbic acid by DPPH. When a mixture of ascorbic acid and (+)-catechin was reacted with DPPH, ascorbic acid scavenged DPPH radical faster than (+)-catechin. Ascorbic acid also scavenged DPPH radical faster than ethyl gallate and alpha-tocopherol. When (+)-catechin was reacted with DPPH, the B-ring of (+)-catechin changed to an o-quinone structure. However, it was reduced to (+)-catechin by ethyl gallate or alpha-tocopherol. alpha-Tocopherol and ethyl gallate had almost identical antioxidative activities. Therefore, the order of radical-scavenging ability (speed) suggested by our 13C NMR study was as follows: ascorbic acid > alpha-tocopherol = ethyl gallate > (+)-catechin.

Antioxidants↗
PubMed2005

Effects of structure on radical-scavenging abilities and antioxidative activities of tea polyphenols: NMR analytical approach using 1,1-diphenyl-2-picrylhydrazyl radicals.

Tea (Camellia sinensis) leaves contain various antioxidants such as ascorbic acid (1) and polyphenols. This study tries to clarify the molecular mechanisms underlying the antioxidative and radical-scavenging activities of these antioxidants, and the reactivities of each antioxidant have been compared against that of the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH, 2) using nuclear magnetic resonance (NMR) analysis. Catechol (3) and (+)-taxifolin (4) were oxidized to o-quinone by 2. However, ethyl protocatechuate (5) and quercetin (6) were not oxidized to o-quinone, even though they possess a catechol structure. The radical-scavenging ability of o-dihydroxyl phenolic compounds with a conjugated olefinic double bond (e.g., 6) was superior to that of compounds without this bond (e.g., 4), whereas the ability of o-dihydroxyl phenolic compounds possessing a conjugated carbonyl bond (5) was inferior to that of compounds lacking this bond (3). Vicinal trihydroxyl phenolic compounds with a conjugated olefinic double bond [e.g., myricetin (7)] had an inferior scavenging ability as compared with compounds lacking this bond [e.g., pyrogallol (8)], but 7 was a better scavenger than compounds with a conjugated carbonyl double bond [e.g., ethyl gallate (9)]. In addition, vicinal trihydroxyl phenolic compounds (e.g., 9) were superior to o-dihydroxyl phenolic compounds (e.g., 6). Finally, 1 scavenged radicals more quickly than 8.

Antioxidants↗
PubMed1998

NMR Analytical Approach To Clarify the Antioxidative Molecular Mechanism of Catechins Using 1,1-Diphenyl-2-picrylhydrazyl.

Each tea catechin was reacted with 1,1-diphenyl-2-picrylhydrazyl (DPPH), and the reaction mixture was subjected to NMR analysis. The antioxidation mechanism of (+)-catechin [(+)-C] is considered to be due to the change of the B-ring to an o-quinone structure at first because of the appearance of two carbonyl signals. This is substantiated by trapping the compound as an adduct of a 1,2-phenylenediamine to an o-quinone. (-)-Epicatechin [(-)-EC] was also confirmed to give a similar result, but in the case of (-)-epigallocatechin [(-)-EGC] and ethyl gallate (EG) no carbonyl signals were observed. The antioxidation mechanisms of (-)-EGC and EG are different from those of (+)-C and (-)-EC. This may be one of the reasons for the differences of the antioxidative activities between the two types of catechins.

Journal Article↗
PubMed2000

Effect of pretreatment antibiotic resistance to metronidazole and clarithromycin on outcome of Helicobacter pylori therapy: a meta-analytical approach.

Our purpose was to define the effect of pretreatment Helicobacter pylori resistance to metronidazole or to clarithromycin on the success of antimicrobial therapy. We used 75 key words to perform a literature search in MEDLINE as well as manual searches to identify clinical treatment trials that provided results in relation to H. pylori susceptibility to metronidazole and clarithromycin or both during the period 1984-1997 (abstracts were not included). Meta-analysis was done with both fixed- and random-effect models; results were shown using Galbraith's radial plots. We identified 49 papers with 65 arms for metronidazole (3594 patients, 2434 harboring H. pylori strains sensitive to metronidazole and 1160 harboring resistant strains). Metronidazole resistance reduced effectiveness by an average of 37.7% (95% CI = 29.6-45.7%). The variability in the risk difference for metronidazole was 122.0 to -90.6 and the chi-square value for heterogeneity was significant (P<0.001). Susceptibility tests for clarithromycin were performed in 12 studies (501 patients, 468 harboring H. pylori strains sensitive to clarithromycin and 33 harboring resistant strains). Clarithromycin resistance reduced effectiveness by an average of 55% (95% CI = 33-78%). We found no common factors that allowed patients to be divided into subgroups with additional factors significantly associated with resistance. In conclusion, metronidazole or clarithromycin pretreatment resistant H. pylori are the main factors responsible for treatment failure with regimens using these compounds. If H. pylori antibiotic resistance continues to increase, pretherapy antibiotic sensitivity testing might become necessary in many regions.

Anti-Bacterial Agents↗
PubMed1999

Coping with breast cancer: a cluster analytic approach.

The aim of this study was to generate distinct clusters of women with breast cancer, and to evaluate differences between clusters with respect to decisional control, psychological adjustment, and frustration expression. Thirty-seven Stage I and 33 Stage II newly diagnosed breast cancer patients from two medical oncology clinics participated. A cluster analysis of the coping data produced three distinct patient clusters. The primary finding was that women from the low avoidance coping cluster were significantly better adjusted than women from the remaining clusters. Women from the low avoidance coping cluster also preferred more active involvement in treatment decision-making. Further research is needed to prospectively detail the mechanisms by which cognitive avoidance hampers psychological adjustment to cancer.

Adaptation, Psychological↗
PubMed2001

Quality of life in breast cancer patients: a cluster analytic approach. Empirically derived subgroups of the EORTC-QLQ BR 23--a clinically oriented assessment.

Quality of life (QOL) questionnaires are integrated into clinical trials in order to evaluate different treatments, and rarely used in a diagnostic sense. The aim of this study was to identify clinically meaningful subgroups by means of established QOL tools. Since January 1995, a field study funded by the German Ministry of Health was conducted to evaluate quality of care of breast cancer patients in eastern Thuringia. During the follow-up period, the European Organization of Research and Treatment of Cancer (EORTC), Quality of Life C30 and the breast specific module BR23 were mailed. One-hundred-fifty-eight women answered both questionnaires. A cluster analysis was performed to distinguish subgroups on the basis of QOL-BR23 scores. According to the QOL outcomes, four subgroups could be described. There was a strong relation to operative treatment (p < 0.05), while no association with the adjuvant treatment strategy was observed. The subsets identified on the basis of BR23 scores were significantly related to all C30 domains. It was possible to demonstrate the clinical validity in terms of clinical and sociodemographic data. No association was found with the marital status or the highest level of education, while a worsening of the financial situation was associated. It could be shown that a distinction of patient subgroups based on clinically meaningful BR23 data is possible. Subgroups with specific profiles could be identified. In the future, the characterisation of subgroups could provide a possibility to generate indications for specific supportive interventions.

Aged↗
PubMed2000

Near infrared with principal component analysis as a novel analytical approach for nanoparticle technology.

PURPOSE: To progress in the characterization of a poly(MePEGcyanoacrylate-co-hexadecylcyanoacrylate) (poly(PEGCA-co-HDCA) copolymer and the nanoparticles formed from this copolymer. METHODS: Poly(PEGCA-co-HDCA) at a MePEG/hexadecyl ratio of 1:4 was investigated by 1H-NMR and near infrared spectroscopy. The nanoparticle suspensions, obtained by the methods of nanoprecipitation or emulsion--solvent evaporation, as well as the crude nanoparticles and their dispersion medium--were analyzed by MePEG measurement, 1H-NMR, and near infrared spectroscopy. RESULTS: The 1H-NMR results showed that the (poly(PEGCA-co-HDCA) copolymer obtained bore lateral hydrophilic MePEG chains and lateral hydrophobic hexadecyl chains in a final ratio of 1:4. However, this ratio, although reproducible from batch to batch, represented only a mean value for different molecular species. Indeed, our results demonstrated the formation of more hydrophobic poly(alkyl-cyanoacrylate) oligomers (with a higher content of hexadecyl chains) and other more hydrophilic oligomers (with a higher MePEG content). Only the more hydrophobic oligomers were able to form solid pegylated nanoparticles. As far as these nanoparticles were concerned, determination of their MePEG content allowed the calculation of a distance of 1.2 nm and 1.05 nm between 2 grafted MePEG chains at the nanoparticle surface, when obtained by nanoprecipitation and emulsion-solvent evaporation, respectively. Moreover, when the same copolymer batch was used, different nanoparticles were obtained according to the preparation method, as seen by near infrared spectroscopy. CONCLUSIONS: The nanoparticles obtained by nanoprecipitation or emulsion-solvent evaporation of poly(PEGCA-co-HDCA) 1:4 copolymer displayed a different supramolecular organization, as evidenced by the near infrared spectroscopy results. Moreover, these nanoparticles showed surface characteristics compatible with a long circulating carrier.

Colloids↗
PubMed2004

Measurement structure of the Turkish translation of the Child Behavior Checklist using confirmatory factor analytic approaches to validation of syndromal constructs.

The new correlated 8-factor measurement structure of the Child Behavior Checklist for ages 6-18 (CBCL/6-18; T. M. Achenbach & L. A. Rescorla, 2001) derived from an American sample was used as a benchmark to evaluate its generalizability to Turkish general population (N = 5,195) and clinical (N = 963) samples. Item-level confirmatory factor analysis (CFA) was used to evaluate the adequacy of the correlated 8-factor model across 3 sample conditions (general population, clinical, and combined sample whose Total Problems scores were above the Turkish national median). The results supported the generalizability of the overall measurement structure of the CBCL to the Turkish population.

Child↗
PubMed2006

Duplex scanning compared with intra-arterial angiography in diagnosing peripheral arterial disease: three analytical approaches.

BACKGROUND: This study was undertaken to assess the reliability of duplex scanning, as compared with digital subtraction angiography, in diagnosing peripheral arterial disease of the lower limbs. PATIENTS AND METHODS: 60 legs were studied. Each leg was divided in 5 arterial segments, from aortoiliac to popliteal. Duplex scanning and digital subtraction angiography were performed. The disease in each segment was assessed as significant or insignificant or classified into five categories concerning the grade of stenosis (patent vessel or no diameter reduction, mild stenosis, i.e. 1-19% diameter reduction, moderate and severe stenosis, i.e. 20-49% and 50-99% diameter reduction, respectively, and occluded vessel). Three statistical approaches were applied: calculating sensitivity and specificity, Kappa statistics, and weighted Kappa value. Median grades of arterial stenosis across different segments, according to angiography measurements, were also calculated. RESULTS: The duplex sensitivity in detecting significant lesions ranged from 0.46 to 0.88. The Kappa values of agreement between duplex and angiography ranged from 0.35 to 0.64. Weighted Kappa values ranged from 0.45 to 0.72. Median grades of arterial lesions ranged from 2 (interquartile range 1-2) to 4 (3-4) and differed significantly (Kruskal-Wallis H test, p < 0.001). CONCLUSIONS: The sensitivities and specificities suggested various duplex reliabilities in detecting significant arterial disease across different lower limbs segments. The Kappa values, in general, testified duplex's insufficient accuracy in grading the severity of stenosis. However, weighted Kappa values confirmed duplex's better ability to approximate the grade of stenosis. The arterial segments themselves were unevenly affected with the peripheral arterial disease.

Aged↗
PubMed2000

The classification of first episode schizophrenia: a cluster-analytical approach.

OBJECTIVE: This paper examines, using data from the Cantabria First Episode Schizophrenia Study, the usefulness of subdividing, using a cluster analysis technique, this schizophrenia population into subgroups with similar symptoms profiles in terms of SANS and SAPS. METHOD: Diagnostic characteristics were determined using the Present State Examination (PSE-9) and the SANS/SAPS. Premorbid adjustment was assessed using a scale developed combining the Gittelman and Klein's Scales, and the Goldstein's scales. Social Adjustment was evaluated using the WHO-DAS. In addition clinical histories were used to assess the patients' clinical course. RESULTS: Our schizophrenic patients could be subtyped into four categories: negative, positive non-paranoid, simple and disorganized schizophrenia. There is an absence of significant association between the majority of the variables investigated and the four-cluster model. CONCLUSION: Even though our sample could be subtyped into different categories, the model does not show predictive power according to the 3-year follow-up data.

Acute Disease↗
PubMed2000

Oral health changes in an adult Norwegian population: a cohort analytical approach.

OBJECTIVES: The purpose of this analysis was to study temporal variation in oral health in an adult population. The cohort analysis comprised 1) estimation of longitudinal, cross-sectional, and time-lag differences in caries and treatment experience of the adult population in Trøndelag from 1973 to 1983 and to 1994; 2) assessment of which of the effects of age, period and cohort was the most plausible explanation for the observed differences and 3) discussion of causal and other factors underlying the effects of age, period and cohort. METHODS: Cohort analysis was used to study changes in oral health over time. Study participants were selected by random sampling in 1973, 1983, and 1994 (n = 1959, n = 3195, n = 2341 respectively). The methods of data collection comprised standardised clinical measurements and a self-administered questionnaire. Cohort tables were established to analyse changes in DFT from 1973 to 1983 and DFT and DFS from 1983 to 1994. RESULTS: Four patterns of changes in oral health were identified from adolescence to older adulthood. They point in different directions which indicate that complex processes are present. There were two and three significant changes in the subsets of analysis. Assumptions and conditions that allow identification of separate cohort, period, and age effects appeared not to be present. The pattern of changes was consistent with main effects of both age, period, and cohort. The effects were discussed from the perspective of the chosen frame of explanatory factors. CONCLUSIONS: The changes in oral health between populations in 1973, 1983 and 1994 were the combined consequences of simultaneously occurring factors that account for both age, period and cohort effects.

Adolescent↗