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PubMed1998

Simulation methodology for estimating financial effects of telemedicine in West Virginia.

Understanding the full financial effects of telemedicine systems on payers, providers, and patients has been hampered by the lack of data from full-fidelity systems operating at a steady state. The vast majority of telemedicine systems in the United States have yet to achieve their full potential in serving their target populations and are operating well below capacity. The purposes of this research are two-fold: (1) to develop a methodology that compensates for the limited availability of empirical data on the financial effects of telemedicine; and (2) to test this methodology in a comprehensive telemedicine system in West Virginia. The proposed methodology utilizes simulation modeling techniques for evaluating the financial performance of a mature telemedicine system. It is particularly suitable for analyzing large, complex systems that have not yet achieved steady-state operation. Although complex, the methodology can be described simply as consisting of two major steps. The first is the identification of all of the relevant variables and parameters for modeling. The second consists of simulating "real world" decision situations involving all relevant variables and parameters. The relation among the variables and parameters are described in terms of mathematical equations. The ability of the researcher to estimate the financial effects of a given telemedicine system is a function of the extent to which the resulting model approximates conditions of the real world; i.e., the fit between model and reality.

Algorithms↗
PubMed2004

Environmental health physics-50 years of progress.

Environmental health physics is an interdisciplinary field, involving study of the release, transport, and fate of radioactive material in the environment. Further, it addresses the interaction of humans with radioactive materials within the ambient (outdoor) environment and with the environments associated with modern technology and lifestyles. It also involves both naturally occurring and artificially produced radionuclides with the former generally being by far the highest source of exposure. In fact, doses from naturally occurring radionuclides are increasingly being used as a benchmark for the establishment of dose rate limits for people. Because of the pioneering work of early environmental health physicists, models exist today that can be used to assess the potential impacts of new nuclear facilities prior to their operation. In fact, these people represent the branch of the health physics profession who conducted environmental monitoring programs and performed the associated research studies that led to the identification of the principal radionuclides of interest, the major pathways and mechanisms through which they expose people, and the doses that may result from radioactive materials in the natural and technologically enhanced environments. One of their most important contributions was the identification and quantification of many of the key parameters that serve as input to such models. Monitoring of nuclear weapons development facilities used during and after World War II was the initial stimulus for the establishment of environmental health physics programs. Thereafter, these programs were expanded both nationally and globally, as a result of the atmospheric weapons testing programs of nations such as France, the People's Republic of China, the former Soviet Union, the United Kingdom, and the United States. Additional stimuli were provided by the development of the commercial nuclear power industry. Current environmental programs, particularly within the U.S., focus on decontamination and decommissioning of dormant facilities from these earlier defense and commercial programs. The range of the environmental health physics aspects of these activities is the subject of this paper. Presented at the end of the paper is a summary of some of the more important lessons that have been learned. As will be noted, this is an exciting field that will present challenges to health physicists for years to come.

Background Radiation↗
PubMed2005

Environmental health physics: 50 years of progress.

Environmental health physics is an interdisciplinary field, involving study of the release, transport, and fate of radioactive material in the environment. Further, it addresses the interaction of humans with radioactive materials within the ambient (outdoor) environment and with the environments associated with modern technology and lifestyles. It also involves both naturally occurring and artificially produced radionuclides with the former generally being by far the highest source of exposure. In fact, doses from naturally occurring radionuclides are increasingly being used as a benchmark for the establishment of dose rate limits for people. Because of the pioneering work of early environmental health physicists, models exist today that can be used to assess the potential impacts of new nuclear facilities prior to their operation. In fact, these people represent the branch of the health physics profession who conducted environmental monitoring programs and performed the associated research studies that led to the identification of the principal radionuclides of interest, the major pathways and mechanisms through which they expose people, and the doses that may result from radioactive materials in the natural and technologically enhanced environments. One of their most important contributions was the identification and quantification of many of the key parameters that serve as input to such models. Monitoring of nuclear weapons development facilities used during and after World War II was the initial stimulus for the establishment of environmental health physics programs. Thereafter, these programs were expanded both nationally and globally, as a result of the atmospheric weapons testing programs of nations such as France, the People's Republic of China, the former Soviet Union, the United Kingdom, and the United States. Additional stimuli were provided by the development of the commercial nuclear power industry. Current environmental programs, particularly within the U.S., focus on decontamination and decommissioning of dormant facilities from these earlier defense and commercial programs. The range of the environmental health physics aspects of these activities is the subject of this paper. Presented at the end of the paper is a summary of some of the more important lessons that have been learned. As will be noted, this is an exciting field that will present challenges to health physicists for years to come.

Background Radiation↗
PubMedDate not supplied

A quantitative study of age-related changes in the vascular architecture of the rat cerebral cortex.

A quantitative study of age related changes in the vascular architecture of the rat cerebral cortex is described. A special vessel-filling technique, which allowed the simultaneous fixation of the vasculature, aided the identification of the vessels in histological sections. Vascular parameters, which included the total number of vessel fragments, a blood volume and a vessel wall-surface area index were obtained using a Quantimet 720 shape-analysing computer. In animals aged 13-83 weeks, there was an increase in the above vascular parameters which could mainly be attributed to an increase in the number of vessels with a diameter greater than 8 micrometers. In very old rats, aged 124 weeks, the vascularity of the cerebral cortex was severely reduced. These changes, which are very similar to those reported in the ageing human cerebral cortex, may be explained by either direct or indirect effects on the cerebral vasculature. Possible mechanisms are discussed in relation to similar changes observed in the cerebral vasculature after several different insults.

Aging↗
PubMed2005

Image processing for IMRT QA dosimetry.

We have automated the determination of the placement location of the dosimetry ion chamber within intensity-modulated radiotherapy (IMRT) fields, as part of streamlining the entire IMRT quality assurance process. This paper describes the mathematical image-processing techniques to arrive at the appropriate measurement locations within the planar dose maps of the IMRT fields. A specific spot within the found region is identified based on its flatness, radiation magnitude, location, area, and the avoidance of the interleaf spaces. The techniques used include applying a Laplacian, dilation, erosion, region identification, and measurement point selection based on three parameters: the size of the erosion operator, the gradient, and the importance of the area of a region versus its magnitude. These three parameters are adjustable by the user. However, the first one requires tweaking in extremely rare occasions, the gradient requires rare adjustments, and the last parameter needs occasional fine-tuning. This algorithm has been tested in over 50 cases. In about 5% of cases, the algorithm does not find a measurement point due to the extremely steep and narrow regions within the fluence maps. In such cases, manual selection of a point is allowed by our code, which is also difficult to ascertain, since the fluence map does not yield itself to an appropriate measurement point selection.

Algorithms↗
PubMed2001

Distinguishing cochlear pathophysiology in 4-aminopyridine and furosemide treated ears using a nonlinear systems identification technique.

To test the adequacy of physiologic indices derived from a third-order polynomial model quantifying cochlear mechano-electric transduction (MET), 24 Mongolian gerbils were exposed to either 250-mM glucose (control), 150-mM 4-aminopyridine (4-AP), or 30-mM furosemide solutions applied to the round window (RW) membrane. The cochlear microphonic (CM) was recorded from the RW in response to 68- and 88-dB SPL Gaussian noise. A nonlinear systems identification technique (NLID) provided the frequency-domain parameters and physiologic indices of the polynomial model of MET. The control group showed no change in both compound action potential (CAP) thresholds and CM. Exposure to 4-AP and furosemide resulted in a similar elevation in CAP thresholds and a reduction in CM. However, the polynomial model of MET showed different changes. The operating point, slope, and symmetry of the MET function, the polynomial model parameters, and related nonlinear coherences differed between the experimental groups. It is concluded that the NLID technique is sensitive and specific to alterations in the cochlear physiology.

4-Aminopyridine↗
PubMed2003

Behavioral criterion quantifying the edge-constrained effects on foams in the standing wave tube.

The influence of mounting conditions on the measurement of the sound absorption coefficient is investigated. More specifically, the effects of a circumferential edge constraint applied on elastic foams in a standing wave tube are studied. The objective is to identify the foams for which it is possible to measure the theoretical absorption coefficient using the tube. This identification relies on the evaluation of a new parameter, the Frame Acoustical Excitability (FAE), based on the foams' physical properties. In order to quantify the difference between the measured and theoretical absorptions, a linear correlation coefficient is evaluated for a wide range of foams with various sample sizes. The calculated correlation coefficients are then sorted in terms of the FAE. It is shown that as the value of FAE increases, the difference between the measured and theoretical absorption coefficients becomes more significant. A critical value of FAE, below which the theoretical absorption can be efficiently measured using the tube, is established. Through the use of this elasto-acoustic criterion, an experimenter can make an educated guess as to which absorption is measured with the tube: the theoretical absorption or one that is affected by either the edge constraint or the sample's dimensions.

Journal Article↗
PubMed1992

Deferoxamine test and PTH serum levels are useful not to recognize but to exclude aluminum-related bone disease.

The use of noninvasive diagnostic tools, like the deferoxamine (DFO) test and serum iPTH, to identify aluminum-related bone disease has proved to be inadequate due to false-negative cases; therefore, bone biopsy becomes a necessary diagnostic procedure. Our purpose was to verify whether these non-invasive parameters, appropriately used, may result valid in the identification of patients not at risk of Al toxicity, therefore restricting the need for histologic evaluation. We studied 68 hemodialyzed patients, aged 49.0 +/- 11.6 years, with a M/F ratio of 37/31 and a dialytic age of 85.0 +/- 47.0 months, by means of bone biopsy, DFO test and serum C-PTH. 19.1% of the cases had positive stainable Al and/or high bone Al content (greater than 60 mg/kg/dw) and could be intoxicated. To obtain the highest sensitivity, we selected the following limit values: the lower limit of increment so far proposed for DFO test positivity (greater than 150 micrograms/l) and a value capable of selecting patients with pathologic osteoclasia for C-PTH (greater than 15 ng/ml). With these limits, four different groups of patients were recognized: group A, DFO test positive and PTH high, n = 12; group B, DFO test positive and PTH low, n = 6; group C, DFO test negative and PTH high, n = 30; group D, DFO test negative and PTH low, n = 20. In group B, which could be anticipated as being at higher risk, we actually found the highest (p less than 0.05) bone Al content as compared to other groups, associated with a reduced bone formation rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1978

Spirometric changes in normal children with upper respiratory infections.

Recent evidence that certain uncomplicated upper respiratory infections induce pulmonary function abnormalities in adults prompted a prospective study in children, in whom such infections occur more frequently. In a longitudinal study, 55 children 2.5 to 11 years of age were observed for a mean duration of 2 years. Spirometry and lung volume studies were obtained routinely every 3 months, during each upper respiratory infection, and 4 weeks after illnes, providing data for 617 "well" and 237 "illness" observations. After grouping of data by sex and age (less than 84 of greater than 84 months), each spirometric parameter was analyzed using linear regression with individual identification, height, and clinical status (normal versus upper respiratory illness) as independent variables. Adjusted mean values of forced vital capacity, 1-sec forced expiratory volume, peak expiratory flow, maximal mid-expiratory flow, and expiratory flow at 50 per cent of the forced vital capacity all decreased during upper respiratory illness. The data suggest that lower respiratory tract involvement without signs or symptoms of lower airway or alveolar disease occurs with upper respiratory illnesses of varied etiologic origin in childhood.

Body Height↗
PubMed2005

A multistep bioinformatic approach detects putative regulatory elements in gene promoters.

BACKGROUND: Searching for approximate patterns in large promoter sequences frequently produces an exceedingly high numbers of results. Our aim was to exploit biological knowledge for definition of a sheltered search space and of appropriate search parameters, in order to develop a method for identification of a tractable number of sequence motifs. RESULTS: Novel software (COOP) was developed for extraction of sequence motifs, based on clustering of exact or approximate patterns according to the frequency of their overlapping occurrences. Genomic sequences of 1 Kb upstream of 91 genes differentially expressed and/or encoding proteins with relevant function in adult human retina were analyzed. Methodology and results were tested by analysing 1,000 groups of putatively unrelated sequences, randomly selected among 17,156 human gene promoters. When applied to a sample of human promoters, the method identified 279 putative motifs frequently occurring in retina promoters sequences. Most of them are localized in the proximal portion of promoters, less variable in central region than in lateral regions and similar to known regulatory sequences. COOP software and reference manual are freely available upon request to the Authors. CONCLUSION: The approach described in this paper seems effective for identifying a tractable number of sequence motifs with putative regulatory role.

Algorithms↗
PubMed2005

Tandem machine learning for the identification of genes regulated by transcription factors.

BACKGROUND: The identification of promoter regions that are regulated by a given transcription factor has traditionally relied upon the identification and distributions of binding sites recognized by the factor. In this study, we have developed a tandem machine learning approach for the identification of regulatory target genes based on these parameters and on the corresponding binding site information contents that measure the affinities of the factor for these cognate elements. RESULTS: This method has been validated using models of DNA binding sites recognized by the xenobiotic-sensitive nuclear receptor, PXR/RXRalpha, for target genes within the human genome. An information theory-based weight matrix was first derived and refined from known PXR/RXRalpha binding sites. The promoter region of candidate genes was scanned with the weight matrix. A novel information density-based clustering algorithm was then used to identify clusters of information rich sites. Finally, transformed data representing metrics of location, strength and clustering of binding sites were used for classification of promoter regions using an ensemble approach involving neural networks, decision trees and Naïve Bayesian classification. The method was evaluated on a set of 24 known target genes and 288 genes known not to be regulated by PXR/RXRalpha. We report an average accuracy (proportion of correctly classified promoter regions) of 71%, sensitivity of 73%, and specificity of 70%, based on multiple cross-validation and the leave-one-out strategy. The performance on a test set of 13 genes showed that 10 were correctly classified. CONCLUSION: We have developed a machine learning approach for the successful detection of gene targets for transcription factors with high accuracy. The method has been validated for the transcription factor PXR/RXRalpha and has the potential to be extended to other transcription factors.

Algorithms↗
PubMed2005

Malignant mesothelioma: current status of histopathologic diagnosis and molecular profile.

Malignant mesothelioma of the pleura is a relatively rare neoplasm that has been estimated to account for 20 deaths per million males per year in North America and Europe. A causative association has been well established with asbestos exposure. Paradoxically, the incidence of this tumor continues to rise despite public efforts to reduce, contain or eliminate exposure to asbestos fibers over the past few decades. Another paradoxical feature of the disease is that the majority of malignant mesotheliomas represent morphologically low-grade, well-differentiated neoplasms, yet they follow a relentlessly aggressive and virtually uniformly fatal outcome. For this reason, identification of clinical, morphologic, immunohistochemical or molecular genetic parameters is of extremely limited value for prognostication. Surprisingly, for a disease that currently has no known cure, one of the major problems still lies in establishing the correct diagnosis. Diagnosis acquires a particular relevance in light of the medicolegal ramifications of this disease, and diagnosis of malignant mesothelioma is still fraught with difficulties. Despite the advances in modern diagnostic techniques, no specific markers or morphologic features exist that are exclusive to these tumors. Herein, the current status of malignant mesothelioma diagnosis is reviewed, including the possible contributions of modern molecular techniques for their diagnosis.

Animals↗
PubMed1989

[Biochemical characterization of calf sera used in the maintenance of cell cultures used in virology].

Eight lots of the calf sera employed to supplement culture media for the cultivation of animal cells, of widespread use in virology obtained from calves above and below six months of age were rated as good or as poor cell growth promoters according to their growth promoting capacity (GPC). Parameters related to macronutrients contained in these serum lots were then evaluated with the purpose of establishing their biochemical profiles. The results obtained can be considered as normal values for apparently healthy animal donors. Fluctuations found between the data of this investigation and those mentioned in the literature for certain biochemical parameters are probably due to the methodology employed, the breed and age of the animals, or even to regional diet. Student's "t" test was applied for the statistical analysis of the results and demonstrated that, as far as serum fractions were concerned, no significant differences occurred between sera rated as good and poor cell growth promoters, taking tc = 2.45. For calf sera from animals above and below six months of age, two tests relating to alfa and beta fractions were significant (t = 2.68 and 2.61 respectively). It was demonstrated that the evaluation of the biochemical parameters mentioned "per se" neither leads to the identification of calf sera presenting good or poor GPC, nor of sera harvested from calves younger or older than six months.

Animals↗
PubMedDate not supplied

Detection of intracytoplasmic cytokines by flow cytometry.

Flow cytometry has been used as a powerful technique for studying cell surface antigen expression as well as intracellular molecules. Its capability of analyzing multiple parameters simultaneously on a single cell has allowed identification and studies of functional cell subsets within heterogeneous populations. In this respect, several techniques have been developed during the past few years to study cytokine-producing cells by flow cytometry in humans and several animal models.

Animals↗
PubMed1999

Control of hypertension in postoperative patients.

In this paper, adaptive control systems have been developed for the closed-loop control of mean arterial pressure using vasoactive drugs. An adaptive algorithm based on generalized predictive control law has been presented. A adaptive PI controller has been designed. The recursive least-square identification algorithm is used for on-line parameter estimation. The supervisor is added to provide safety and efficacy of control under the consideration of the physical and physiological constraints. Extensive computer simulation in the presence of unpredictable disturbances shows the system is capable of inducing hypertension.

Algorithms↗
PubMed2002

Grouping and identification of sequence tags (GRIST): bioinformatics tools for the NEIBank database.

NEIBank is a project to develop and organize genomics and bioinformatics resources for the eye. As part of this effort, tools have been developed for bioinformatics analysis and web based display of data from expressed sequence tag (EST) analyses. EST sequences are identified and formed into groups or clusters representing related transcripts from the same gene. This is carried out by a rules-based procedure called GRIST (GRouping and Identification of Sequence Tags) that uses sequence match parameters derived from BLAST programs. Linked procedures are used to eliminate non-mRNA contaminants. All data are assembled in a relational database and assembled for display as web pages with annotations and links to other informatics resources. Genome projects generate huge amounts of data that need to be classified and organized to become easily accessible to the research community. GRIST provides a useful tool for assembling and displaying the results of EST analyses. The NEIBank web site contains a growing set of pages cataloging the known transcriptional repertoire of eye tissues, derived from new NEIBank cDNA libraries and from eye-related data deposited in the dbEST section of GenBank.

Animals↗
PubMed2004

Hemodynamic response to laparoscopic cholecystectomy--impacts of increased afterload and ischemic dysfunction of the left ventricle.

The authors describe the results of intra-operative hemodynamic monitoring during laparoscopic cholecystectomy in patients with ischemic left ventricular dysfunction and with significant aortic stenosis. The results in the groups composed of 13 and 12 patients were compared with the findings in 10 young, non-obese, non-smokers without significant cardiovascular history and with normal findings during resting transthoracic echocardiography. Monitoring itself was conducted using transesophageal echocardiography 1) after the induction of anesthesia, 2) after the induction of capnoperitoneum, and 3) after setting the operative anti-Trendelenburg position. The measurements were performed at least in triplicate and the results were processed using ANOVA test. Significant differences were identified in the time course patterns of heart rate, mean arterial pressure, dual product (pressure-rate-product), and cardiac output. In terms of pathophysiology, we believe that the most important achievement was the identification of different time course patterns of individual parameters in the respective groups. The results in the group of patients with aortic stenosis were based particularly on the different time course of the mean arterial pressure, while the results in patients with ischemic disease were more dependent on the time course of the heart rate. Very interesting is a drop of peripheral vascular resistance after positioning of these patients which could be explained only partially by a beta-blocking or ACEI medication. In clinical terms, the most important finding was probably that no complications occurred in the entire group of 35 patients, of which 25 suffered from severe organic cardiopathies.

Aortic Valve Stenosis↗
PubMed1985

[Detection of Mycoplasma arthritidis and Mycoplasma fermentans antibodies in rheumatoid arthritis patients by an immunoenzyme method].

The optimum parameters of the immunoenzyme assay system for the identification of antibodies to M. arthritidis and M. fermentans in the sera of patients with rheumatoid arthritis have been established. The investigation has shown that the products obtained by the ultrasonic disintegration of the biomass of M. arthritidis and M. fermentans can be used as soluble antigens for adsorption on the polystyrene surface of plates. The use of the immunonenzyme assay, specially modified, has made it possible to establish that antibodies to M. arthritidis can be detected in 6.5% of cases, antibodies to M. fermentans, in 41.9% of cases and the association of antibodies to M. arthritidis and M. fermentans, in 41.9% of cases. At the same time antibodies to M. arthritidis have been found to belong mainly to IgM and antibodies to M. fermentans, to IgG or to IgG and IgM simultaneously.

Adsorption↗