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At least 811 records · Page 45Linked to original sources
PubMed2002

Distraction of skeletal muscle: evolution of a rat model.

To better study the effects of limb lengthening on skeletal muscle, the authors developed a rat model that uses a miniature external skeletal fixator applied to the tibia of an adult Sprague-Dawley rat. The mounting and lengthening protocols follow the principles developed by Ilizarov. With the initial version of the fixator, the rats had progressive equinus contractures develop because the calf muscles resisted elongation. By incorporating a footplate in the distraction apparatus, tibial lengthening can be achieved without concomitant equinus.

Animals↗
PubMed2003

The need for evolution in healthcare decision modeling.

STATEMENT OF PROBLEM: Many healthcare decisions are difficult because they are complex and have important consequences such as the impact on survival or quality-of-life of individuals and on allocation of limited resources. The present state-of-the-art in healthcare decision modeling is often inadequate to properly assess these decisions. METHODS: Based on a literature search and the experience of the authors, typical methodologies used in healthcare decision analysis modeling are explored and compared with methods used in other practices. An example of hormonal therapy decisions is used. RESULTS: Useful methods that have been developed in other fields are presented. These include methods targeted toward appropriate assessment and representation of the complexity of decisions, assessment of uncertainty, use of nonexpected value decision analysis, and use of multi-attribute decision criteria. CONCLUSION: The state-of-the-art in healthcare decision modeling can be improved through learning from other practices.

Decision Making↗
PubMed2006

Analytic approach to the evolutionary effects of genetic exchange.

We present an approximate analytic study of our previously introduced model of evolution including the effects of genetic exchange. This model is motivated by the process of bacterial transformation. We solve for the velocity, the rate of increase of fitness, as a function of the fixed population size, N. We find the velocity increases with ln N, eventually saturating at an N which depends on the strength of the recombination process. The analytical treatment is seen to agree well with direct numerical simulations of our model equations.

Journal Article↗
PubMedDate not supplied

Perinatal hypoxic-ischemic brain damage: evolution of an animal model.

Early research in the Vannucci laboratory prior to 1981 focused largely on brain energy metabolism in the developing rat. At that time, there was no experimental model to study the effects of perinatal hypoxia-ischemia in the rodent, despite the tremendous need to investigate the pathophysiology of perinatal asphyxial brain damage in infants. Accordingly, we developed such a model in the postnatal day 7 rat, using a modification of the Levine preparation in the adult rat. Rat pups underwent unilateral common carotid artery ligation followed by exposure to systemic hypoxia (8% oxygen) at a constant temperature of 37 degrees C. Brain damage, seen histologically, was generally confined to the cerebral hemisphere ipsilateral to the arterial occlusion, and consisted of selective neuronal death or infarction, depending on the duration of the systemic hypoxia. Tissue injury was observed in the cerebral cortex, hippocampus, striatum, and thalamus. Subcortical and periventricular white matter injury was also observed. This model was originally described in the Annals of Neurology in 1981, and during the more than 20 years since that publication numerous investigations utilizing the model have been conducted in our laboratories as well as laboratories around the world. Cerebral blood flow and metabolic correlates have been fully characterized. Physiologic and pharmacologic manipulations have been applied to the model in search of neuroprotective strategies. More recently, molecular biologic alterations during and following the hypoxic-ischemic stress have been ascertained and the model has been adapted to the immature mouse for specific use in genetically altered animals. As predicted in the original article, the model has proven useful for the study of the short- and long-term effects of hypoxic-ischemic brain damage on motor activity, behavior, seizure incidence, and the process of maturation in the brain and other organ systems.

Animals↗
PubMed1989

[Clinical model concept of the evolution of malignant tumors: implication for hormone therapy of breast cancer].

An analysis is made of current concepts about heterogeneity, instability and autonomy of tumor cells which accounts for the clinical course of incurable, late-stage malignant disease which as such is characterized by a growing independence from growth control mechanisms of the host, by progressive metastatic spread and by unpredictable malignancy associated events. Increasing heterogeneity, instability and autonomy are best demonstrated by the development of resistance phenomena and are potentially reversible processes. This reversibility can be exploited using biological response modifiers. Understanding this triad also helps explain certain clinical phenomena such as qualitative differences in remissions and mixed responses, early vs. late stage disease, and the potential therapeutical hazards which can lead to further tumor heterogeneity. On the breast cancer example further clinical implications are illustrated, namely receptor heterogeneity, autocrine autonomy, and combination therapy with hormones. The concepts discussed are the basis for the development of non-toxic tumor therapies which are aimed less at tumor cell kill than at stabilization.

Breast Neoplasms↗
PubMed1980

The "one day at a time" syndrome in post-transplant evolution: the regressive megalomanic model versus the progressive hypomanic model.

After kidney transplantation patients experience an initial period of euphoria which is usually followed by a phase of disillusionment and depression. At this point the "one day at a time syndrome" appears as an attitude of adaptation and defense. It is proposed that there are two dynamically and prognostically different varieties of this syndrome: A first type represents a regressive megalomanic defense whereby depressive anxiety concerning the rejection of the part-self represented by the graft is conscious but depressive anxiety concerning the eventual death of the whole self is omnipotently denied. This variety of the syndrome is related to a more negative prognosis both psychologically and somatically. The second type of the "one day at a time syndrome" is a progressive hypomanic defense whereby depressive anxiety concerning the rejection of the part-self represented by the graft is present and conscious but relative and does not preclude the conscious depressive anxiety concerning the eventual death of the whole self, which once acknowledged can gradually be mastered, permitting the pursuit of as pleasurable a life as possible. This variety of the syndrome is prognostically more favourable both physically and psychologically.

Adaptation, Psychological↗
PubMed1992

Quality assessment in the medical intensive care unit. Continued evolution of a data model.

Quality assessment and assurance activities in the intensive care unit are complex processes that begin with the definition of the scope of services delivered in the unit with further identification of the important aspects of care. There is also a need to establish indicators of quality, gather data, and finally to organize the data into useful information. There are many approaches to these efforts ranging from establishment of indicators to data collection and analysis of patterns that lead to clarification of the indicators. We chose the latter pathway, specifically utilizing a previously described data model in which information was grouped according to structure, process, and outcome of patient care. In this paper, we focus on the application of the concept of patient days of service for quantification of the utilization of resources as an element of quality. Efficient utilization of resources cannot be effected until data on actual utilization are collected and analyzed.

Data Collection↗
PubMed1994

Antilisterial activity by enterococci in a model predicting the temperature evolution of Taleggio, an Italian soft cheese.

Enterococcus ssp. produced broad-spectrum bacteriocins, which were active against Listeria innocua and Listeria monocytogenes. Inhibition of L. innocua in milk by different starter cultures was evaluated. Milk was inoculated with a conventional starter (Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus mixed cultures) as a sole starter or in combination with inhibitory starter cultures (Enterococcus ssp., bacteriocin-producing strains). Tests were performed under a temperature gradient that reproduced the first 55 h of Taleggio cheese manufacturing and in the presence of rennet. Results indicated that satisfactory inhibition of L. innocua was linked to the combined synergistic antimicrobial effect of pH decrease and bacteriocin production. Overall, data suggested that a potential existed for use of the antagonistic activity from enterococci for protection of Taleggio cheese during ripening, when L. monocytogenes may often reach dangerous concentrations.

Bacteriocins↗
PubMed1990

Quality assessment in the medical intensive care unit: evolution of a data model.

Quality assessment and assurance in the intensive care unit require systematic monitoring and evaluation of patient care and its outcome. For analysis of these activities, data must be organized to reflect changes in such factors as patient types, ages, and lengths of stay. A model was developed to group data from the Cleveland Clinic Hospital medical intensive care unit into structural, process, and outcome categories. Development and application of the model are described.

Data Collection↗