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PubMed2000

Saline-filled breast implant safety and efficacy: a multicenter retrospective review.

Our center undertook an industry-funded, outcomes-based, multicenter, retrospective review to evaluate the safety and efficacy of saline-filled breast implants. Our review was part of a pre-market approval review process mandated by the U.S. Food and Drug Administration. The design of our review was modeled on a Plastic Surgery Educational Foundation outcomes study previously conducted by our center. For this study, several significant changes were made to our previous protocol, including improved patient tracking, stronger biostatistical support, and a mandatory 10-year minimum patient follow-up period. Physician-reported and patient-reported data on 450 patients with 882 saline-filled breast implants placed between January 1, 1980, and June 30, 1986, were obtained. Mean patient follow-up period was 13.0 years. Most implants (93.9 percent) were placed for breast augmentation. Seventy-four percent were placed in a submammary position; 25.6 percent, subpectorally; and 0.2 percent, subcutaneously. The overall complication rate was 20.2 percent. Reoperation for capsular contracture or implant deflation was necessary in 104 of 450 patients (23.1 percent). Deflation occurred in 73 implants (8.3 percent) and was underreported according to the physicians' record review alone. This deflation rate is higher than the 5.5 percent previously reported by our center. However, 26 of these 73 deflations (35.6 percent) occurred in a single cohort of patients at one center using Surgitek saline implants. If this cohort is excluded, the deflation rate drops to 5.8 percent, a figure more consistent with data published in the literature and found in our previous study. Of the 73 deflations, spontaneous deflation was reported for 50 (74.6 percent), and the remainder were iatrogenic. Actuarial survival of the non-Surgitek implants was 98.4 percent to 99.8 percent at 5 years and 96.9 percent to 98.9 percent at 10 years (95 percent confidence interval). Risk factors for implant deflation included the use of Surgitek saline-filled implants (odds ratio = 17.5, p < 0.01), use of Heyer-Schulte and Mentor model 1800 implants (odds ratio = 3.0, p < 0.01), and implant size greater than 450 cc (odds ratio = 1.01, p < 0.02). Risk factors for capsular contracture included submammary implant position (odds ratio = 2.05, p = 0.03) and implant size greater than 450 cc (odds ratio = 1.01, p < 0.01). Overall, satisfaction was high: 93 percent of patients were "satisfied" or "very satisfied" with their implants. As in our earlier study, risk factors for patient dissatisfaction were reconstruction after mastectomy (odds ratio = 7.6, p = 0.011), significant breast firmness (odds ratio = 6.2, p < 0.001), and patient desire for smaller implants (odds ratio = 3.0, p = 0.020). In conclusion, our review provides additional outcomes-based evidence that saline-filled breast implants remain a safe, effective alternative to silicone gel-filled models.

Breast Implantation↗
PubMed2003

Longitudinal trends of hemoglobin levels in a Japanese population--RERF's Adult Health Study subjects.

Conflicting results have been reported on the long-term relationship between hemoglobin (Hb) level and age. We analyzed that relationship over a 40-yr period in a Japanese population, adjusting for the effects of sex, birth cohort, smoking, and anemia-associated diseases. We used Hb levels measured biennially between 1958 and 1998 for 4858 Adult Health Study subjects of the Radiation Effects Research Foundation. Using the mixed-effects model, we showed that the aging Hb profile varied by sex (P < 0.001) and birth cohort (P < 0.001). Male Hb levels peaked in the third and fourth decades and then decreased while female Hb levels dipped slightly in the third decade, peaked in the sixth and seventh, and then decreased. Levels were higher in younger cohorts. The rate of Hb decline after the sixth decade of life was greater for subjects with anemia-associated diseases (P = 0.002). The annual rate of decline between 70 and 80 yr of age for disease-free men ranged from 0.083 to 0.042 g/dL and for disease-free women from 0.049 to 0.036 g/dL. Levels were higher for ever-smokers (P < 0.001), more so for women than men. A decreasing trend in Hb concentration with advancing age was detected for elderly men and women after controlling for anemia-associated diseases, suggesting that anemia in the elderly is due not only to disease but also to aging. Cohort and smoking effects on Hb levels were also observed.

Adolescent↗
PubMed1992

Innovative instructional programs for students with language or behavioral disorders.

We described creative and innovative language programs for students with LLD and BD, or both. There are three models of learning that have had considerable impact on how language services have been designed and executed for these two populations of students. Our principal argument is that there is a fourth approach or model based on empowerment. We presented the premises and principles of the empowerment model and described two programs using empowerment as the foundation for the provision of communication and language services. Language and communication programs grounded in an empowerment model offer greater possibilities for students to acquire the discourses necessary for successful participation in the culture of school, as well as the cultures in which they participate outside of school. Discovering strengths and competencies across a wide spectrum of learning affords students opportunities for developing self-knowledge based in capability and adeptness rather than in deficiency and impairment. The emergence, unfolding, and eventual maturation of these competencies and capabilities are critical not only to those students who discover them, but also to the future of all of us.

Behavior Therapy↗
PubMed1999

Nurses' cognitive structural models of work-based stress.

This study examined the causes of stress experienced by National Health Service nurses in England over the course of a single week with the aim of generating a cognitive structural model. Qualitative data served as the foundation of a network study which employed inductive eliminative analysis. These data were also analysed using conventional qualitative methods and by content analysis. The results were consistent with previous studies that identified a number of primary sources of stress. However, the network study indicated that two systems of causation were operating. The first centres on inadequate staffing levels, which were seen as leading to poor attitudes and abilities among colleagues, multiple work roles and lack of support. Lack of support also contributed to powerlessness and poor attitudes and abilities. The behaviour of managers was strongly endorsed as a direct cause of stress, but the strongest explanatory link was through staffing levels and powerlessness. The second system of causation related patients' suffering to stress. The qualitative data validated the network study results through elaborating the understanding of the respondents' nominated causes. Discussion focused on the pressure and frustration experienced by nurses because of organizational factors and interaction effects with the caring nature of nursing work. It is suggested that nursing discourse is subordinated to managerial and biomedical discourse reflecting the relative powerlessness of nurses. The extent to which such powerlessness is primarily a result of the failure of nurses to assert themselves or intrinsic organizational factors is not clear. The consequences of a stressed and demoralized nursing workforce on the quality of patient care and risk profile are identified as the focus for future research.

Cognition↗
PubMed2002

Rat laryngeal transplant model: technical advancements and a redefined rejection grading system.

The rat laryngeal transplant model, introduced in 1992, laid the basic science foundation that contributed to the first successful human larynx transplant in 1998. Over 1,500 rat transplants later, numerous modifications have improved the model, increasing the initially reported evaluability rate of 50% to almost 100%. The observed histologic rejection process has been altered, as well. We report the technique modifications, as well as the results of a new study using nonimmunosuppressed, allogenic transplantations, in order to define a new rejection grading system. Using the updated model, we performed 50 transplantations between LBN(f1) donor rats and Lewis recipients. Larynges from 8 groups of 5 to 10 animals were harvested at intervals between 1 and 20 days after transplantation. The larynges were examined grossly and microscopically in a blinded manner for evidence of rejection. A multivariable linear regression model was used to define a new rejection grading scale. All 50 animals survived their assigned posttransplantation period. No animals exhibited vascular thromboses, for an evaluability rate of 100%. Histologic criteria in 7 categories and gross criteria in 5 categories demonstrated increased rejection proportional to the amount of time after transplantation. The equation [Group = -2.209 + 0.465 x (Size) + 0.901 x (VA Flow) + 0.613 x (Muscle) + 1.040 x (Thyroid)] reproducibly grades rejection on the basis of gross and histologic findings. New modifications to the rat laryngeal transplant model have conferred greatly improved animal survival rates and anastomotic patency rates. Additionally, the observed rates of rejection have been reduced in comparison to those of initial studies. This updated rejection staging system will be used to compare immunosuppressive regimens in future rat laryngeal transplant studies.

Animals↗
PubMed2026

Episode clustering in phylogenetic networks.

MOTIVATION: The classical duplication episode clustering (EC) model introduced by Guig&#xf3; et&#xa0;al. in the 1990s provides a foundational approach for inferring genomic duplication events crucial to understanding genome evolution. This model clusters single gene duplications from a collection of gene trees at locations in the species tree to minimize the total number of such locations, called duplication episodes. However, it does not capture reticulate evolutionary histories. RESULTS: Here, we introduce NetEC, a novel extension of this problem to phylogenetic networks. To solve NetEC, we first develop a polynomial-time dynamic programming (DP) algorithm for testing whether a given set of network nodes can serve as episode locations. We then propose a main inference algorithm that utilizes this DP component to optimize the episode count; while the feasibility test runs in polynomial time, the full optimization has exponential worst-case complexity, and an optional heuristic mode is provided for larger instances. We also propose an extended episode analysis procedure that identifies additional genomic duplication candidates below reticulation nodes, complementing the main algorithm by resolving potential upward clustering of duplications induced by reticulation. We evaluate our method on simulated data and on an empirical Pandanales dataset comprising over 29&#x2009;000 gene trees, demonstrating exact and accurate inference of genomic duplication events even in the presence of multiple reticulations. AVAILABILITY AND IMPLEMENTATION: All experiments were conducted using the NetEC tool (https://github.com/ppgorecki/netec), with all input data, scripts, and parameter settings for reproduction available in the same repository.

Phylogeny↗
PubMed2005

Active and dynamic information fusion for facial expression understanding from image sequences.

This paper explores the use of multisensory information fusion technique with Dynamic Bayesian networks (DBNs) for modeling and understanding the temporal behaviors of facial expressions in image sequences. Our facial feature detection and tracking based on active IR illumination provides reliable visual information under variable lighting and head motion. Our approach to facial expression recognition lies in the proposed dynamic and probabilistic framework based on combining DBNs with Ekman's Facial Action Coding System (FACS) for systematically modeling the dynamic and stochastic behaviors of spontaneous facial expressions. The framework not only provides a coherent and unified hierarchical probabilistic framework to represent spatial and temporal information related to facial expressions, but also allows us to actively select the most informative visual cues from the available information sources to minimize the ambiguity in recognition. The recognition of facial expressions is accomplished by fusing not only from the current visual observations, but also from the previous visual evidences. Consequently, the recognition becomes more robust and accurate through explicitly modeling temporal behavior of facial expression. In this paper, we present the theoretical foundation underlying the proposed probabilistic and dynamic framework for facial expression modeling and understanding. Experimental results demonstrate that our approach can accurately and robustly recognize spontaneous facial expressions from an image sequence under different conditions.

Algorithms↗
PubMed1980

Medical problem-solving: a reanalysis.

Data derived from high-fidelity simulation studies of medical diagnostic reasoning are reanalyzed and critiqued. Results from the reanalyses do not support the earlier findings. The reanalyses also raise questions about the validity of a psychological model of diagnostic inquiry that formed the foundation of the high-fidelity simulation research. Suggestions regarding alternate methods for conducting research on diagnostic problem-solving are offered.

Diagnosis↗
PubMed2006

Morphological variations in a tooth family through ontogeny in Pleurodeles waltl (Lissamphibia, Caudata).

Most nonmammalian species replace their teeth continuously (so-called polyphyodonty), which allows morphological and structural modifications to occur during ontogeny. We have chosen Pleurodeles waltl, a salamander easy to rear in the laboratory, as a model species to establish the morphological foundations necessary for future molecular approaches aiming to understand not only molecular processes involved in tooth development and replacement, but also their changes, notably during metamorphosis, that might usefully inform studies of modifications of tooth morphology during evolution. In order to determine when (in which developmental stage) and how (progressively or suddenly) tooth modifications take place during ontogeny, we concentrated our observations on a single tooth family, located at position I, closest to the symphysis on the left lower jaw. We monitored the development and replacement of the six first teeth in a large growth series ranging from 10-day-old embryos (tooth I1) to adult specimens (tooth I6), using light (LM), scanning (SEM), and transmission electron (TEM) microscopy. A timetable of the developmental and functional period is provided for the six teeth, and tooth development is compared in larvae and young adults. In P. waltl the first functional tooth is not replaced when the second generation tooth forms, in contrast to what occurs for the later generation teeth, leading to the presence of two functional teeth in a single position during the first 2 months of life. Larval tooth I1 shows dramatically different features when compared to adult tooth I6: a dividing zone has appeared between the dentin cone and the pedicel; the pulp cavity has enlarged, allowing accommodation of large blood vessels; the odontoblasts are well organized along the dentin surface; tubules have appeared in the dentin; and teeth have become bicuspidate. Most of these modifications take place progressively from one tooth generation to the next, but the change from monocuspid to bicuspid tooth occurs during the tooth I3 to tooth I4 transition at metamorphosis.

Animals↗
PubMed1989

Operator limitations in farm tractor overturn recognition and response.

Accounting for nearly half of all work-related farm tractor injuries annually, tractor side and rear overturn continue to be an ongoing problem. The causes of both side and rear overturns may be grouped into design-related and human factors-related categories. This review addresses the latter, highlighting those information processing bottlenecks, some of which may be aided through training or stability indicator devices. It is argued that tractor instability must first be perceived before a corrective response may be taken. Evidence was drawn from orientation perception, tractor rollover response time, and driving studies to describe an overall model of the tractor operator attempting to stay within stable operating conditions. With this more precise model of the tractor operator, a foundation is provided for further research on the operator-tractor interface.

Journal Article↗
PubMed1987

Towards a new pluralism.

The thesis of this paper is that the future development of health services, cross-nationally, is likely to be influenced more by changes in organisational, managerial and information technologies than by ideological preferences. Such changes are likely to make the traditional ideological and conceptual distinction between the public and private sector redundant, as boundaries become blurred. The trend, it is argued, is towards forms of organisations based on networks rather than hierarchies and towards for-profit or co-operative health care enterprises complementing large-scale public organisations. Such forms of health care organisation, it is further argued, are likely to promote adaptability in the face of rapid change and satisfy producer demands for autonomy. The thesis is illustrated by the recent experience of Britain where more flexible organisational patterns are emerging which, however, do not comfortably fit into the traditional public/private conceptual antithesis despite the ideological bias of the Conservative Government towards market solutions. Finally, the paper concludes that American ideas and experience may be a poor guide for European countries, since change starts from a very different organisational and intellectual foundation.

Government↗
PubMed1996

The epidemiology of heartwater: Establishment and maintenance of endemic stability.

Although heartwater (Cowdria ruminantium infection) is one of the most economically important tick-borne diseases of sub-Saharan Africa, its epidemiology he's remained poorly understood until recently. New data, suggesting that heartwater is present in an endemically stable state in much of sub-Saharan Africa and demonstrating vertical transmission of Cowdria ruminantium in the field, have altered previously accepted views on heartwater epidemiology. In this paper, Sharon Deem and colleagues present an overview of the epidemiology of heartwater based on recent studies, discuss the factors that make endemic stability possible, make recommendations for future directions in research, and provide a foundation for the development of epidemiological models.

Journal Article↗
PubMed1996

On the interpretation of certainty factors in expert systems.

Despite the strong theoretical foundation the Bayesian probabilistic approach to model uncertainty in medicine meets many difficulties at the implementation step. One of these difficulties is related to a large amount of conditional probabilities to be assessed and in many cases this task was recognised to be practically insoluble. The MYCIN certainty factors model is a widely distributed pragmatical approach for modeling reasoning under uncertainty that substantially simplifies the problem, at the sacrifice of theoretical soundness. One can determine certainty factors as a function of prior and posterior probability. However, this approach is only consistent with the modularity axiom for certainty factors for tree-structure inference networks, which is rarely true for practical applications. In this paper we abandon the requirement of a direct probabilistic interpretation of certainty factors and build a model of propagation of uncertainty in terms of absolute belief and belief updates. We describe our model for propagating uncertainty in terms of matrix multiplication with specifically defined addition and multiplication which correspond to parallel and sequential combinations of certainty factors. It is possible to define these operations in such a manner that they form a field, and therefore to obtain some useful properties. Finally we present a method of determining certainty factors from statistical data using nonlinear regression and illustrate it with a leukemia diagnostics problem.

Artificial Intelligence↗
PubMed2005

End of life care for adult cystic fibrosis patients: facilitating a good enough death.

BACKGROUND: There is little empirical research on end of life care for CF patients from qualitative, psychosocial perspectives or which examines how staff members manage specific issues raised by cystic fibrosis deaths. This study examined how a number of recent deaths have been handled in an adult CF centre in the UK. METHODS: Multi-perspective psychosocial interview study with patients, staff, and relatives of decedents. Team meetings were observed. Interviews were analysed using a qualitative methodology (Interpretative Phenomenological Analysis). Observational analyses were used to assess the team's interactions when dealing with end of life issues with patients. RESULTS: Analysis of interviews uncovered themes which addressed the team's questions on care and support of patients with end-stage CF as follows: talking about death and dying; the multidisciplinary team; difficulties for the staff and saying goodbye; active versus palliative care. As a result of psychological input with the multidisciplinary team, staff felt supported and developed the ability to talk openly and in good time to patients regarding their deaths and their wishes for treatment at the end of life. CONCLUSION: The team felt that they had reached a foundation upon which to propose a model of care at the end of life for adult cystic fibrosis patients.

Adult↗
PubMed2005

Weather-dependent change of cesium, strontium, barium and tellurium contamination deposited as aerosols on various cultures.

Various types of plants (wheat, bean, lettuce, radish and grass) were contaminated by dry deposition of radioactive aerosols ((137)Cs, (85)Sr, (133)Ba and (123 m)Te) in order to supplement the radio-ecological data necessary for operational post-accidental codes. A few days after deposition, rainfalls were applied to these cultures to evaluate the influence of some characteristics of the rain on the contamination of the culture over time. On the other hand, for wheat and bean, the influence of the humidity condition of the foliage at the contamination time was considered. For a given plant species at a given vegetative stage, the four radionuclides were intercepted in an identical way. The interception varied from 30% for bean (young sprout) to 80% for lettuce (near maturity). The global transfer factor values were dependent on both the radionuclides and the plant species; nevertheless, a higher value was obtained for cesium, regardless of the plant and the rainfall (from 0.006 m(2)kg(fresh)(-1) for wheat-grains - contaminated at the shooting stage - or for bean-pods - contaminated at the pre-flowering stage - to 0.1m(2)kg(fresh)(-1) for a whole lettuce). The analysis of the results allowed us on the one hand, to extract parameter values of the foliar transfer directly usable in operational codes, in particular those relating to barium and tellurium, unknown until then, and on the other hand, to lay the foundations of a future, more mechanistic model, taking into account the foliar processes in a finer way.

Aerosols↗
PubMedDate not supplied

Functional genomic technologies: creating new paradigms for fundamental and applied biology.

New technologies that analyze the behavior of thousands of genes in parallel are creating, for the first time, a foundation of data for building integrated models of cellular processes. This review discusses the general issues of utilizing genomic methods in fundamental and applied research settings, using the study of stress responses and improvement of secondary metabolite production as examples. A fusion of concepts from biological and nonbiological disciplines, including mathematics, computer science, physics, chemistry, and engineering, is required to address the theoretical and experimental challenges facing the field of genomics, and together promise great breakthroughs in our understanding and engineering of cellular systems.

Biotechnology↗
PubMed2006

Modelling data across labs, genomes, space and time.

Logical models and physical specifications provide the foundation for storage, management and analysis of complex sets of data, and describe the relationships between measured data elements and metadata - the contextual descriptors that define the primary data. Here, we use imaging applications to illustrate the purpose of the various implementations of data specifications and the requirement for open, standardized, data formats to facilitate the sharing of critical digital data and metadata.

Animals↗