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PubMed1987

The numerical approach to classification: a medical application to develop a typology for facial pain.

Applications of numerical taxonomy in medicine are relatively rare. We describe an application in which a new typology is developed for the classification of pain distribution in patients with temporomandibular pain dysfunction syndrome. The methodology of the numerical approach is presented and key issues are highlighted, especially relating to validation of taxonomic structure. From the dendrogram obtained by Ward's hierarchical method, five pain groups are distinguished which relate systematically to anatomy and are clinically meaningful. Cluster structure is subjected to a battery of reproducibility tests and is found to be broadly reproducible for different algorithms and sub-samples of subjects. Finally, the new typology is shown to have heuristic value in providing fresh insight into the nature of a complex syndrome.

Algorithms↗
PubMed1990

Estimating benefits of screening from observational cohort studies.

Analysis and interpretation of observational studies of screening effectiveness is difficult because several biases threaten validity, including the structural healthy screenee bias, length bias, and effects of lead time. Although methods for the analysis of observational studies of screening effectiveness have been proposed, most have limitations such as incomplete control of length bias, or a heavy reliance on distributional assumptions. In this report we present a method for the analysis of observational cohort studies of screening effectiveness. Although developed independently and formulated specifically for estimating benefits of screening, our approach is implied by a more general approach developed previously by Robins. Our approach, in contrast to other available methods, avoids the healthy screenee bias, and length and lead time bias, and allows an empirical approach to analysis that need not depend highly on distributional assumptions. We illustrate application of the approach with analysis of published data from a study of breast cancer screening.

Bias↗
PubMed2004

Understanding the tropospheric transport and fate of agricultural pesticides.

Many field monitoring studies have indicated the substantial role of the troposphere as both a sink and transport medium for pesticides. At the same time, this is the least studied and understood environmental compartment in regards to pesticide fate. Although the fundamental principles behind volatilization and tropospheric reactivity are well understood, it is becoming increasingly apparent that the ability to quantitatively measure flux and reaction rates in the air will continue to pose problems for researchers. To date, most deterministic models that try to simulate real world conditions generally fail to provide tropospherically relevant flux and reaction rates because it is virtually impossible to scale down all possible interactions occurring in a near-infinite reservoir. Better field methods for determining flux are emerging and more ambient air monitoring studies are being conducted. This growing database of information, together with an understanding of physicochemical properties and use of expert systems, has increased the predictive capability for estimating volatilization flux of pesticides. Unfortunately, there are very limited environmental data on the tropospheric reaction rates of pesticides, and more experimental studies using semivolatile to low-volatility pesticides or their more volatile homologues are required to validate existing structure-activity relationship (SAR) model predictions. The development of new analytical strategies using elevated temperatures for assessing semivolatile to low-volatility pesticide reaction rates and products may provide an alternative approach to the need for controlled environmental temperature data. Recent international workshops organized by the Health Council of The Netherlands for developing uniform approaches for assessing exposure risks to pesticides in air exemplify efforts to synchronize flux with environmental fate information for determining human health and ecological risks. When more detailed pesticide information is desired, especially in high-use agricultural areas, where exposure to humans and nontarget ecological communities is a major concern, field flux measurements and downwind monitoring, together with experimental fate studies, should be considered. The integration of models, empirical testing, and real world monitoring will provide the ultimate safety net needed for assessing exposure risks to airborne pesticides.

Atmosphere↗
PubMed1979

Classification of human placental villi. II. Morphometry.

Villi of placental tissue obtained from normal term placentae at Caesarean section were embedded in Epon. Semithin sections were subjected to morphometry. The villi were first grouped according to the modified classification proposed in the foregoing paper. The parameters examined include villous numbers, size, vascularity, volume of trophoblast and connective tissue. The measured values differ markedly from those obtained from paraffin sections. Statistically significant differences exist between the different types of villi in various parameters, providing further evidence supporting the validity of the structural classification suggested.

Cell Membrane↗
PubMed1993

Psychometric properties of the parental bonding instrument in a Spanish sample.

The Parental Bonding Instrument was translated into Spanish and administered to a sample of 205 Spanish primiparae 3 days after childbirth. Reliability, factorial structure and predictive validity for affective disorders were evaluated. The Spanish version of the PBI has psychometric features similar to those described in other cultures. However, the results suggest that in future research the predictive power of the "Control" factor in affective disorders might be improved by splitting it into two subfactors: "Overprotection" and "Restraint".

Adult↗
PubMed1980

Identification of a carbohydrate receptor recognized by uropathogenic Escherichia coli.

Earlier investigations have shown that pyelonephritic Escherichia coli specifically recognize and bind to carbohydrate structures correlated to the P blood group antigens. These findings are confirmed and extended in this study. Twenty-two of 23 nonselected E. coli strains from children with acute febrile pyelonephritis failed to agglutinate human erythrocytes lacking the antigens within the P blood group system. Only one of 32 faecal isolates exhibited this specific agglutinating property. The new informatin in this paper is that P2k erythrocytes, containing only the Pk antigen, were agglutinated to the same extent by pyelonephritic E. coli strains, giving further support to the proposal that the Pk glycosphingolipid is related to the receptor for pyelonephritic E. coli. In addition, the importance of the oligosaccharide moiety of the Pk glycosphingolipid for the binding of E. coli was further investigated. The synthesized disaccharide alpha-D-Galp-(1-4)-beta-D-Galp-1-O-0-NO2 inhibited the agglutination of human erythrocytes caused by two pyelonephritic E. coli strains at concentrations of less than 1 mM. Hence, the minimal receptor structure recognized by these E. coli strains appears to be the alpha-D-Galp-(1-4)-beta-D-Galp structure. How generally valid this observation may be needs further investigation. The findings may open new possibilities for diagnosis and treatment of urinary tract infection.

Animals↗
PubMed1984

Morphological changes in rat hepatocytes in primary culture induced by Misonidazole, desmethylmisonidazole and Ro 03-8799.

Isolated rat hepatocytes in early primary culture were incubated in the presence of three substituted nitroimidazoles currently of clinical interest as tumour radiosensitisers. The effects of 3h treatments with Misonidazole (MISO), Desmethylmisonidazole (DESMISO) and the basic compound Ro 03-8799 were monitored both directly from treatment and following a 24h 'recovery' period. Morphological changes were observed by SEM and TEM and included effects on the plasma membrane and the nucleus. The plasma membrane of DESMISO and 03-8799 treated cells was characterised by blebbed regions not present in control cultures, and considered indicative of an early toxic insult. Blebs were most evident in 03-8799 treated hepatocytes where they often contained coils of endoplasmic reticulum within the ground plasma. Blebbed areas were less evident 24h after the removal of the drugs from surviving cells. An increased aggregation of peripherally located heterochromatin within the nucleus was the other main morphological alteration induced by nitroimidazole treatment. This was again more prevalent in 03-8799 and DESMISO exposures; and particularly in cells demonstrating membrane damage. Parallel viability studies indicated an efficacy of the nitroimidazole towards rat liver parenchymal cells in primary culture of Ro 03-8799 greater than DESMISO greater than MISO. This fitted the order predicted from the morphological findings and from previously published clinical data. The validity of monitoring structural parameters as a means of initially indicating lesion sites following drug treatments in the hepatocyte cytotoxic screening model is considered.

Animals↗
PubMed2004

Mannan transglycosylase: a novel enzyme activity in cell walls of higher plants.

Mannan transglycosylase is a novel cell wall enzyme activity acting on mannan-based plant polysaccharides in primary cell walls of monocotyledons and dicotyledons. The enzyme activity was detected by its ability to transfer galactoglucomannan (GGM) polysaccharides to tritium-labelled GGM-derived oligosaccharides generating tritium-labelled GGM polysaccharides. Mannan transglycosylase was found in a range of plant species and tissues. High levels of the enzyme activity were present in flowers of some kiwifruit (Actinidia) species and in ripe tomato (Solanum lycopersicum L.) fruit. Low levels were detected in mature green tomato fruit and activity increased during tomato fruit ripening up to the red ripe stage. Essentially all activity was found in the tomato skin and outermost 2 mm of tissue. Mannan transglycosylase activity in tomato skin and outer pericarp is specific for mannan-based plant polysaccharides, including GGM, galactomannan, glucomannan and mannan. The exact structural requirements for valid acceptors remain to be defined. Nevertheless, a mannose residue at the second position of the sugar chain and the absence of a galactose substituent on the fourth residue (counting from the non-reducing end) appear to be minimal requirements. Mannan-based polysaccharides in the plant cell wall may have a role analogous to that of xyloglucans, introducing flexibility and forming growth-restraining networks with cellulose. Thus mannan transglycosylase and xyloglucan endotransglycosylase, the only other known transglycosylase activity in plant cell walls, may both be involved in remodelling and refining the cellulose framework in developmental processes throughout the life of a plant.

Actinidia↗
PubMed2003

Prevalence of primary headaches in Italian elderly: preliminary data from the Zabút Aging Project.

We describe preliminary 1-year prevalence data of recurrent migraine headache (MH), tension-type headache (TTH), and other headaches (OH) in a rural elderly population. A door-to-door two-phase survey was conducted on all elderly (>or=65 years) residents of a rural village in southern Italy. Participants underwent a two-phase screening including a validated semi-structured questionnaire for headaches based on the International Headache Society criteria, and a neurological evaluation. Recurrent headache was defined as 3 or more attacks within the past 12 months. Out of 1031 participants evaluated, 225 (21.8%) suffered from recurrent headaches. One-year prevalence rates for headaches were respectively 4.6% for MH, 16% for TTH, and 1.3% for OH. For MH and TTH, but not for OH, prevalence rates were significantly higher for women than for men. Only MH prevalence rates significantly decrease with increasing age. In our population, about one-fifth of elderly subjects suffered from recurrent primary headaches. Prevalence rates were higher in women, and tended to decline with increasing age.

Aged↗
PubMed2006

Suicide probability scale and its utility with adolescent psychiatric patients.

This study examined the factor structure, reliability, and validity of the Suicide Probability Scale (SPS) in a sample of 226 (80 male, 146 female) adolescent psychiatric inpatients. Confirmatory factor analyses provided only some support for the original subscales. Exploratory factor analyses revealed some overlap with the original scales, but the factors differed by gender. Internal consistency of the original factors was somewhat better than the factors derived from this sample. A negative change in SPS scores over the course of the inpatient admission was related to risk for readmission due to repeat suicidal behavior.

Adolescent↗
PubMed1993

The validation event: a critical appraisal?

Apart from the perennial concern with finance, questions of 'quality' and 'accountability' will be the principle themes in the higher education debate in the 1990s. The whole issue of 'quality' and 'accountability' has become critically important to the success or otherwise of colleges of nursing and midwifery in convincing their multiple stakeholders (clients, patients, students and purchasers) that they should have a place in the marketing of nursing and midwifery education. The validation process is an important component of the formalized quality assurance mechanism of a course. There have, however, been little or no empirical data relating to the effect of validation processes on quality of courses and, more important, in the long term, quality of care. The following issues are explored in the paper. How are 'quality' and 'accountability' defined within the context of a market orientated system? How is 'peer review' to be interpreted within a purchaser led system? Are practice outcomes prioritised within educationally led, practice-based courses? Is there a part to play for continuing external regulation? We suggest that recent developments in nursing and midwifery education have often been undermined, during validation events, by structural processes for conformity. Such a regression to the conventional has been strengthened by the absence of new conceptions of quality deliberately designed to match these innovatory courses. Conceptions, that is, framed in terms distinct from the traditional model in which quality in higher education tends to be regarded as largely an attribute of disciplinary knowledge. Finally, we suggest that the decisive determinant of professional skill, is the personal standards, the professionalism and the self-respect of the individual teacher.

Accreditation↗
PubMed1986

An empirical typology of problem drinkers from the Michigan Alcoholism Screening Test.

In a program of treatment for persons convicted of driving while intoxicated, data from 504 male participants were collected and analyzed to identify groups homogeneous with respect to symptoms and consequences of problem drinking as indicated on the Michigan Alcoholism Screening Test (MAST). Cluster analysis of MAST responses yielded 7 such groups, differing in level and pattern of alcohol-related problems. This classification was shown: (a) to be homogeneous and reliable; (b) to discriminate effectively within several sets of external criteria--specifically, scales and profiles from the Minnesota Multiphasic Personality Inventory (MMPI) and clinical ratings of reasons for drinking and of participation and outcome from treatment; and (c) to predict alcoholism criteria more powerfully than dimensional use of the MAST. Categorical representation of alcoholism from its psychosocial symptoms was shown to be a valid and valuable structural approach.

Adult↗
PubMed2006

A systematic investigation of the rate laws valid in intracellular environments.

Recently there has been significant interest in deducing the form of the rate laws for chemical reactions occurring in the intracellular environment. This environment is typically characterized by low-dimensionality and a high macromolecular content; this leads to a spatial heterogeneity not typical of the well stirred in vitro environments. For this reason, the classical law of mass action has been presumed to be invalid for modeling intracellular reactions. Using lattice-gas automata models, it has recently been postulated [H. Berry, Monte Carlo simulations of enzyme reactions in two dimensions: Fractal kinetics and spatial segregation, Biophys. J. 83 (2002) 1891-1901; S. Schnell, T.E. Turner, Reaction kinetics in intracellular environments with macromolecular crowding: simulations and rate laws, Prog. Biophys. Mol. Biol. 85 (2004) 235-260] that the reaction kinetics is fractal-like. In this article we systematically investigate for the first time how the rate laws describing intracellular reactions vary as a function of: the geometry and size of the intracellular surface on which the reactions occur, the mobility of the macromolecules responsible for the crowding effects, the initial reactant concentrations and the probability of reaction between two reactant molecules. We also compare the rate laws valid in heterogeneous environments in which there is an underlying spatial lattice, for example crystalline alloys, with the rate laws valid in heterogeneous environments where there is no such natural lattice, for example in intracellular environments. Our simulations indicate that: (i) in intracellular environments both fractal kinetics and mass action can be valid, the major determinant being the probability of reaction, (ii) the geometry and size of the intracellular surface on which reactions are occurring does not significantly affect the rate law, (iii) there are considerable differences between the rate laws valid in heterogeneous non-living structures such as crystals and those valid in intracellular environments. Deviations from mass action are less pronounced in intracellular environments than in a crystalline material of similar heterogeneity.

Fractals↗
PubMed2004

Relationship between child abuse history, trauma, and dissociation in Russian college students.

OBJECTIVE: The research was conducted to determine the relationship between violent trauma, child abuse history, and dissociative symptoms in a Russian population. METHOD: Three hundred and one undergraduate students from Moscow State Linguistics University participated in the study and completed the Dissociation Continuum Scale, the Violence History Questionnaire, the Traumatic Events Survey (TES), and a demographic measure. RESULTS: Scores on dissociation and its subfactors were significantly higher in the Russian sample compared to the normative US group. The best predictors for dissociation were experiencing a violent trauma, child abuse history, and/or the experience of a fearful event. Those participants with a prior child abuse history were more symptomatic after adult trauma than those with no such history. CONCLUSIONS: The relationship between trauma/abuse and dissociation is unlikely to be a result of suggestion by therapists or media exposure, since the correlation appears in a Russian population who are relatively unexposed to these suggestive sources. The validity, reliability, and structure of the dissociation measure were relatively similar in American and Russian samples.

Adolescent↗
PubMed2026

Seawater immersion reshapes the temporal dynamics of traumatic brain injury and reveals mitochondrial oxidative stress as a modifiable therapeutic target.

Traumatic brain injury (TBI) evolves through time-dependent secondary injury, but whether seawater (SW) immersion merely amplifies pathology or reshapes the temporal trajectory of post-traumatic biology remains unclear. Here, we applied time-resolved proteomics to mouse brains after controlled cortical impact (CCI) with or without artificial SW immersion at 1, 3, 7, and 28 days post-injury. Trajectory-based proteomic analysis revealed that SW immersion altered the direction, magnitude, timing, persistence, and recovery of protein responses, rather than simply intensifying TBI-induced changes. This remodeled trajectory exhibited phase-specific patterns, including SW-dominant, synergistically enhanced, and attenuated responses, highlighting mitochondrial oxidative stress, inflammatory activation, complement/coagulation disturbance, and impaired structural repair. Phenotypic validation confirmed phase-specific deficits, including acute inflammatory-redox injury, impaired neuronal survival, chronic axon-myelin disruption, and incomplete behavioral recovery. SS-31 partially mitigated selected inflammatory, redox, neuronal, and white matter abnormalities, supporting mitochondrial oxidative stress as a modifiable node rather than the sole driver of trajectory remodeling. These findings identify seawater immersion as a temporal modifier of secondary injury and emphasize that environmental trauma may require trajectory-informed, phase-specific therapeutic interventions.

Animals↗
PubMedDate not supplied

A gender perspective on sleeplessness behavior, effects of sleep loss, and coping resources in patients with stable coronary artery disease.

OBJECTIVE: The primary aim of this study was to systematically compare perceived sleep quality, sleeplessness behavior, sense of mastery, self-esteem, depression, subjective health, and effects of sleep loss in men and women with stable coronary artery disease (CAD). Further aims were to determine possible predictors of poor sleep quality and sense of mastery, as well as the consequences of too little sleep. METHODS: Comparative-correlation and predictive design were used. Patients with a history of stable angina pectoris scheduled to undergo coronary angiography at Linköping University Hospital in Sweden were included. There were 47 women and 88 men (mean age 62.4 years) with CAD. Structured interviews using validated questionnaires covered sleep quality and sleep habits, effects of sleep loss, psychologic resources, and depression. RESULTS: Multiple stepwise regression analysis showed that sleeplessness behavior, depressed mood, female gender, and pharmacologic treatments with inflammation inhibitors significantly (P<.0001) accounted for the variance of poorer sleep quality. The analysis also showed that the following factors in descending order significantly accounted (P<.0001) for the outcome of sleep quality: inability to feel refreshed by sleep, difficulty in maintaining sleep, gastrointestinal problems, too little sleep, final morning awakening time, sleep onset latency, lying down because of daytime tiredness, and daytime physical tiredness. CONCLUSIONS: Compared with men, women with stable CAD may be especially at risk of experiencing poor sleep quality, even when sleeplessness behavior and pharmacologic treatments with inflammation inhibitors are controlled. It is also possible that they may be more at risk of depressed mood.

Adaptation, Psychological↗
PubMed2005

Understanding technology adoption in clinical care: clinician adoption behavior of a point-of-care reminder system.

BACKGROUND: Evaluation studies of clinical decision support systems (CDSS) have tended to focus on assessments of system quality and clinical performance in a laboratory setting. Relatively few studies have used field trials to determine if CDSS are likely to be used in routine clinical settings and whether reminders generated are likely to be acted upon by end-users. Moreover, such studies when performed tend not to identify distinct user groups, nor to classify user feedback. AIM: To assess medical residents' acceptance and adoption of a clinical reminder system for chronic disease and preventive care management and to use expressed preferences for system attributes and functionality as a basis for system re-engineering. DESIGN OF STUDY: Longitudinal, correlational study using a novel developmental trajectory analysis (DTA) statistical method, followed by a qualitative analysis based on user satisfaction surveys and field interviews. SETTING: An ambulatory primary care clinic of an urban teaching hospital offering comprehensive healthcare services. 41 medical residents used a CDSS over 10 months in their daily practice. Use of this system was strongly recommended but not mandatory. METHODS: A group-based, semi-parametric statistical modeling method to identify distinct groups, with distinct usage trajectories, followed by qualitative instruments of usability and satisfaction surveys and structured interviews to validate insights derived from usage trajectories. RESULTS: Quantitative analysis delineates three types of user adoption behavior: "light", "moderate" and "heavy" usage. Qualitative analysis reveals that clinicians of distinct types tend to exhibit views of the system consistent with their demonstrated adoption behavior. Drawbacks in the design of the CDSS identified by users of all types (in different ways) motivate a redesign based on current physician workflows. CONCLUSION: We conclude that this mixed methodology has considerable promise to provide new insights into system usability and adoption issues that may benefit clinical decision support systems as well as information systems more generally.

Attitude of Health Personnel↗
PubMed2005

Computational analysis of type II endoleaks in a stented abdominal aortic aneurysm model.

Insertion of a stent-graft into an aneurysm to form a new (synthetic) blood vessel and prevent the weakened artery wall from rupture is an attractive surgical intervention when compared to traditional open surgery. However, focusing on a stented abdominal aortic aneurysm (AAA), post-operative complications such as endoleaks may occur. An endoleak is the net influx of blood during the cardiac cycle into the cavity (or sac) formed by the stent-graft and the AAA wall. A natural endoleak source may stem from one or two secondary branches leading to and from the aneurysm, labeled types IIa and IIb endoleaks. Employing experimentally validated fluid-structure interaction solvers, the transient 3-D lumen and cavity blood flows, wall movements, pressure variations, maximum wall stresses and migration forces were computed for types IIa and IIb endoleaks. Simulation results indicate that the sac pressure caused by these endoleaks depends largely on the inlet branch pressure, where the branch inlet pressure increases, the sac pressure may reach the systemic level and AAA-rupture is possible. The maximum wall stress is typically located near the anterior-distal side in this model, while the maximum stent-graft stress occurs near the bifurcating point, in both cases, due to local stress concentrations. The time-varying leakage rate depends on the pressure difference between AAA sac and inlet branch. In contrast, the stent-graft migration force is reduced by type II endoleaks because it greatly depends on the pressure difference between the stent-graft and the aneurysm cavity.

Algorithms↗