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At least 1,423 records · Page 79Linked to original sources
PubMed2006

Integration of quantitative DCE-MRI and ADC mapping to monitor treatment response in human breast cancer: initial results.

PURPOSE: The objective of this study was to assess changes in the water apparent diffusion coefficient (ADC) and in pharmacokinetic parameters obtained from the fast-exchange regime (FXR) modeling of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) during neoadjuvant chemotherapy in breast cancer. MATERIALS AND METHODS: Eleven patients with locally advanced breast cancer underwent MRI examination prior to and after chemotherapy but prior to surgery. A 1.5-T scanner was used to obtain T1, ADC and DCE-MRI data. DCE-MRI data were analyzed by the FXR model returning estimates of K(trans) (volume transfer constant), v(e) (extravascular extracellular volume fraction) and tau(i) (average intracellular water lifetime). Histogram and correlation analyses assessed parameter changes post-treatment. RESULTS: Significant (P < .05) changes or trends towards significance (P < .10) were seen in all parameters except tau(i), although there was qualitative reduction in tau(i) values post-treatment. In particular, there was reduction (P < .035) in voxels with K(trans) values in the range 0.2-0.5 min(-1) and a decrease (P < .05) in voxels with ADC values in the range 0.99 x 10(-3) to 1.35 x 10(-3) mm2/s. ADC and v(e) were negatively correlated (r = -.60, P < .02). Parameters sensitive to water distribution and geometry (T(1), v(e), tau(i) and ADC) correlated with a multivariable linear regression model. CONCLUSION: The analysis presented here is sensitive to longitudinal changes in breast tumor status; K(trans) and ADC are most sensitive to these changes. Relationships between parameters provide information on water distribution and geometry in the tumor environment.

Antineoplastic Agents↗
PubMed1982

OPT: a package of computer programs for parameter optimisation in clinical pharmacokinetics.

1 OPT is a series of computer programs designed to assist dose optimisation for individual patients. It is based on Bayesian Statistical Theory and Maximum Likelihood Estimation. 2 OPT uses prior information on the distribution of population pharmacokinetic parameters and plasma drug concentration measurements to obtain the "most likely' set of parameters for the individual. 3 Complex dosage regimes and non-steady state conditions can be handled. 4 OPT is designed for use in a Clinical Pharmacokinetics Laboratory where informed interpretation of results is essential. 5 The drugs for which the system is currently available include theophylline, digoxin, lignocaine, disopyramide, gentamicin and phenytoin (steady state data only).

Administration, Oral↗
PubMed2005

Informal payment for health care: evidence from Hungary.

While there is a growing body of evidence that informal payments for health care are widespread and enduring in the former communist countries of Central and Eastern Europe and Central Asia, evidence on the scale of the phenomenon is not only limited, but what is available is often conflicting. Hungary exemplifies this controversy, as the available literature provides conflicting figures, differing by an order of magnitude among various surveys, with a similarly large difference between survey findings and expert estimates. This study advances understanding of the methodological issues involved in researching informal payments by providing a systematic analysis of the methodology of available empirical research and official statistics on the scale of informal payments in Hungary. The paper explores the potential sources of differences, to assess the scope to reduce the differences between various estimates and to define the upper and lower boundaries within which the true magnitude of informal payments can be expected to lie. Our analysis suggests that in 2001 the overall magnitude of informal payments lay between 16.2 and 50.9 billion HUF (euro 64.8- euro 203.6 million, US dollars 77.1-242.4 million), which amounted to 1.5-4.6% of total health expenditures in Hungary. Looked at this way, informal payments do not seem to be an important source of health care financing. However, as informal payments are unequally distributed among health workers, with the bulk of the money going to physicians, with some not taking any informal payments, family doctors and some specialists may have earned between 60 and 236% of their net official income from this source in 2001. This suggests that it is not the overall amount of informal payment that makes it a policy concern, but the consequences of its unequal distribution among health workers. What is remarkable about informal payments in Hungary is that a relatively small amount of money can keep the system running, which gives rise to the hypothesis that, in certain cases, it is the hope of substantial informal payments in the future that motivates physicians to remain in the system. This is a difficult challenge for policy-makers as it would require a much larger amount of money to achieve equilibrium under any formal alternative.

Delivery of Health Care↗
PubMed2003

Internet-based interaction among brain tumour patients. Analysis of a medical mailing list.

Patients and their care providers are increasingly turning to the internet for information. Being faced with this information of very heterogeneous quality, the physician would do well to be informed about the common internet information sources. We investigated the e-mails of a mailing list (or "support group") serving about 380 brain tumour patients and their care providers. The mails were obtained from an archive and grouped according to their topic. Within 6 months, 3,272 e-mails were distributed to every group member. Alternative treatments were the most frequently discussed topics (15 %). These discussions dealt with serious new strategies as well as dubious drugs and methods. A critical attitude towards "quacks" was common, but not the rule. More than 10 % of the mails dealt with debates about therapeutic strategy and about symptoms. The individual course of the participants' illness was often reported very frankly. Emotional support between members played another great role in the support group. Criticism of physicians was rare compared to recommendations of specific therapists (3 % vs. 4 %) and included lack of empathy or sensibility and poor communication between physicians. The brain tumour mailing list is a communication medium for brain tumour patients and their care providers, which distributes and reproduces information of heterogeneous quality. The physician faced with this information should be unbiased but cautious.

Brain Neoplasms↗
PubMed2006

Integrating medical and genomic data: a successful example for rare diseases.

The recent advances on genomics and proteomics research bring up a significant grow on the information that is publicly available. However, navigating through genetic and bioinformatics databases can be a too complex and unproductive task for a primary care physician. In this paper we present diseasecard, a web portal for rare disease that provides transparently to the user a virtually integration of distributed and heterogeneous information.

Computational Biology↗
PubMed1993

Acute myeloid leukemia: correlation between purine metabolism enzyme activities and membrane immunophenotype.

A total of 34 AML patients with heterogenous age distribution (from 2 years up to 82 years) were observed. Purine metabolism enzyme activities were compared and correlated with membrane immunophenotype. Analysis of bone marrow and peripheral blood samples based on FAB criteria and immunologic phenotyping of acute myeloid leukemia (AML) provided useful--either confirmatory or contradictory-information on the distribution of M1-M6 patients demonstrating a predominance of M1+M2 and M4 groups (44% and 32.4%, respectively). In contrast, it was demonstrated that less frequent subtypes were M3 and M6 (5.9% and 2.9%, respectively). AML subtypes were correlated with expression of surface antigens detected by the following monoclonal antibodies: CD13, CD33, CDw65, CD11b, CD15, CD14, HLA-DR and CD34. On the basis of immunophenotyping we found the following characteristic markers: M1, M2-CD34, HLA-DR, CD13, CD33, CDw65; M3-CD13, CD33, HLA-DR (negative); M4, M5-CDw65, CD14, CD13, CD33 and HLA-DR. CD14 was confirmed to be a typical marker for discriminating myeloid from monocytoid FAB AML subtypes. Analysis of purine metabolism enzyme activities showed that there is a correlation between the values of adenosine deaminase and purine nucleoside phosphorylase and various immunotypes of AML. High ADA/PNP ratio (> 1.0) was found in M1, M2, M3 subtypes. It was due to the increased level of ADA activity (> 100 pkat.10(-6) cells), though these activities overlapped to a certain extent. It was shown that PNP activity simultaneously decreased. With maturation of cells within AML lineage ADA activity decreased and PNP activity increased. This corresponded with ADA/PNP ratio that was < 1.0 in cells of more mature AML subtypes. We found that the enzymatic values were characteristic mainly in cells of M5 (monocytic) AML subtype and were characterized by decreased values of ADA activity with a simultaneous increase in PNP activity. It follows from our results that ADA/PNP ratio enables to discriminate between myeloid and monocytoid subtypes of AML.

Adenosine Deaminase↗
PubMed2001

Organic ion imaging of biological tissue with secondary ion mass spectrometry and matrix-assisted laser desorption/ionization.

Organic secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry can be used to produce molecular images of samples. This is achieved through ionization from a clearly identified point on a flat sample, and performing a raster of the sample by moving the point of ionization over the sample surface. The unique analytical capabilities of mass spectrometry for mapping a variety of biological samples at the tissue level are discussed. SIMS provides information on the spatial distribution of the elements and low molecular mass compounds as well as molecular structures on these compounds, while MALDI yields spatial information about higher molecular mass compounds, including their distributions in tissues at very low levels, as well as information on the molecular structures of these compounds. Application of these methods to analytical problems requires appropriate instrumentation, sample preparation methodology, and a data presentation usually in a three-coordinate plot where x and y are physical dimensions of the sample and z is the signal amplitude. The use of imaging mass spectrometry is illustrated with several biological systems.

Animals↗
PubMed2002

Intraperitoneal distribution of ultrasound contrast medium imaged with B-mode ultrasound and colour-stimulated acoustic emission imaging.

Intraperitoneal port catheter systems for local delivery of cytotoxic drugs require imaging prior to chemotherapy to confirm homogenous distribution of an injected fluid in the entire peritoneal cavity. This study was performed to assess whether contrast-enhanced ultrasound (US) is a suitable imaging modality for this task. Twelve patients with peritoneal carcinosis and an implanted intraperitoneal port catheter system were studied before chemotherapy. Ultrasound examinations were performed after bolus injections of the microbubble contrast medium Levovist. Distribution of the contrast medium in the peritoneal cavity was imaged using B-mode US and colour-stimulated acoustic emission imaging (SAE). Contrast-enhanced CT imaging was used as term of reference for evaluating the US results. Distribution of the microbubbles in the peritoneal cavity was easily detected by both US methods. In 10 of 12 patients a free distribution in all abdominal quadrants was seen with both US techniques. In 2 of 12 patients, CT and US showed contrast medium limited to the perihepatic area. Therapy was stopped and surgical repositioning of the catheter was performed. Ultrasound after intraperitoneal injection of a microbubble contrast agent provides reliable information about the distribution of intraperitoneally injected fluid in the peritoneal cavity. This method is therefore well suited for imaging port catheter systems prior to chemotherapy.

Acoustics↗
PubMed2006

Use of Brugia Rapid dipstick and ICT test to map distribution of lymphatic filariasis in the Democratic Republic of Timor-Leste.

The newly-introduced Brugia Rapid dipstick for filarial antibodies and ICT filarial antigen card test were used to confirm historical data on the distribution of lymphatic filariasis in the Republic of Timor-Leste. Twelve out of thirteen districts were confirmed as being endemic. Brugian filariasis predominates, with an average prevalence of 11.6%. The average prevalence of Bancroftian filariasis was 1.1%. The study demonstrated that the Brugia Rapid test can provide useful information about the distribution of Brugian filariasis in circumstances where it is difficult or impossible to obtain night blood samples for microfilariae.

Adult↗
PubMed1995

Discrimination of speed distributions: sensitivity to statistical properties.

Two experiments examining the ability of human observers to detect differences in the statistical properties underlying velocity distributions were conducted. A four-alternative forced-choice methodology, using four simultaneous velocity distributions, was used in both experiments. In the first experiment the value of one statistical moment (mean, variance, skewness, or kurtosis) was manipulated while the others were held constant. The subjects task was to determine which of four velocity distributions contained the dissimilar value. In the second experiment only the latter three moments were examined. A similar procedure was used, however feedback was given after each trial to maximize observer performance. The results from both experiments indicate that human observers can reliably detect differences in both mean and variance information underlying velocity distributions. The results of this research has important implications for image segmentation and the detection of heading from optic flow.

Discrimination, Psychological↗
PubMed2000

Estimating risks for matching factors in case-control studies.

Matching for factors such as age and sex is a convenient method for minimizing confounding in case-control studies, but it does not allow inferences about the effects of the matching factors unless case ascertainment is virtually complete and the distribution of the matching factors in the source population is known. When this is so, the effect of a particular factor can be estimated by comparing the population distribution of that factor with what is observed in the case series. Such a comparison, however, may itself be confounded by other factors that are related to both the matching factors and the disease under investigation. This article proposes a method for evaluating matching factors as risk factors, which uses information on the distribution of potential confounders in the reference series and exposure relative risk estimates to adjust the person-time proportionality constant in a Poisson regression model. The method is particularly suited to data sets in which many of the elementary matching strata contain few or no cases and/or controls. It makes use of standard analytic procedures, but requires the estimation of an additional variance-covariance component for the estimated Poisson regression coefficients. Further factors that may confound the relationship between exposure and disease are easily accommodated. The method is demonstrated in two examples: a matched case-control study of drugs in relation to the rare blood dyscrasia, agranulocytosis, that was conducted in Europe and Israel, and a case-control study of ovarian cancer in Australia.

Adolescent↗
PubMed1978

Kinetics of desynchronization and distribution of generation times in synchronized cell populations.

The kinetics of the distribution of generation times in synchronized cells can be analyzed by using Fourier transform analysis. Deviations of the experimental data from the curve of completely asynchronous growth reflect the degree of synchrony at a particular time. Fourier transform analysis of these deviations yields the average generation time as well as information on the distribution of generation times characterizing a synchronized culture. A detailed analysis of synchronized cell cultures does not provide any evidence for the existence of a subcycle or a polymodal distribution in generation times. The data do indicate that cell-cell interaction occurs at cell densities as low as 2.5 X 10(3)/cm2. It is also shown that the Eyring-Stover formalism for the dynamics of survival can correctly describe the distribution of the first round of cell divisions in a synchronized culture.

Cell Cycle↗
PubMed2006

Echinococcus granulosus in northern Queensland. 1. Prevalence in cattle.

OBJECTIVE: To determine the prevalence and geographical distribution of hydatidosis and investigate factors that might be expected to influence the prevalence of hydatids in cattle in Queensland north of the Tropic of Capricorn. To determine the effect of natural levels of infection on carcase weight and subsequent economic loss. PROCEDURE: An abattoir survey conducted in 1981 provided information on the distribution, prevalence and viability of hydatid cysts in cattle from all shires north of the Tropic of Capricorn in Queensland. Livers, lungs and spleens from 10,382 cattle were palpated at abattoirs in Cairns, Townsville and Rockhampton to detect hydatid cysts. Prevalence of infection in cattle in each shire was estimated from results of the abattoir study together with reports of infection in a further 22,185 cattle obtained from abattoir records. Linear modelling was used to define the effect of geographical origin, age, breed and sex on prevalence of infection. Differences in the weights of carcases between infected and non-infected cattle of the same age, sex, breed and property of origin were examined. The economic loss to the beef industry in the region surveyed was estimated. RESULTS: Cattle infected with hydatids originated almost entirely from regions to the east of the Great Dividing Range. The mean prevalence inside this zone was 28% compared with 3% in other areas. Viable protoscoleces were found in 0.7% of cysts. Geographical origin and age of the cattle were the most significant factors influencing prevalence. Infection with hydatids had no effect on carcase weight. Economic loss was limited to that associated with condemnations of organs at meat inspection, estimated to be 0.5 million dollars per annum in 1981 and 6 million dollars in 2004. The distribution of hydatids in Queensland north of the Tropic of Capricorn corresponded most closely with the distribution of small wallabies such as Macropus dorsalis (black-striped wallaby), M parryi (whiptail wallaby) and M rufogriseus (red-necked wallaby). CONCLUSIONS: It was concluded that cattle are not an important part of maintaining the life-cycle of E granulosus in Queensland north of the Tropic of Capricorn. Within the endemic zone, which is almost all to the east of the Great Dividing Range, the local pattern of bovine echinococcosis is most likely to be determined by the presence or absence of small species of wallaby such as M dorsalis, M parryi and M rufogriseus.

Abattoirs↗
PubMed2004

Contextual annotation of web pages for interactive browsing.

With the information on the World Wide Web and in specialized databases exploding, researchers and physicians are in dire need to browse efficiently though the large corpus of information resources in their field of interest. The focus is not any longer to find everything related to your interest, but it shifts to zooming in, based on context and expanding again in neighboring knowledge domains. This paper describes an attempt to develop a completely new, interactive way of browsing distributed corpora of information without the need for multiple different queries in different information resources. Classical search engines generally treat search requests in isolation. The results for a given query are identical, and do not automatically take on board the context in which the user made the request. The system described here explores implicit contexts as obtained from the document that the user is reading. The new approach merges the searching and browsing into one combined "read-and-search" mode and alleviates the shift users are normally forced to between searching and reading.

Hypermedia↗
PubMedDate not supplied

Involvement of cardiovascular rehabilitation programs in advance directive education.

BACKGROUND: Cardiac rehabilitation programs represent opportunities to educate patients with cardiac disease about living wills and durable powers of attorney for health care. The extent of advance directive education that is currently provided in cardiac rehabilitation programs, however, is unknown. METHODS: A questionnaire was mailed to nonphysician directors of cardiac rehabilitation programs to determine the programs' involvement in educating enrollees about end-of-life issues and the directors' opinions regarding the appropriateness of such education in cardiac rehabilitation curricula. Data were presented as proportions with 95% confidence intervals (Cls). RESULTS: Of the 1013 cardiac rehabilitation program directors, 845 (83%) responded to the questionnaire, of which 48 stated they were no longer enrolling patients. Of the remaining 797 program directors (83%), 71% (95% CI, 67%-74%) informed patients of their prognosis, but only 18% (95% CI, 15%-20%) and 12% (95% CI, 9%-14%) asked patients if they had a living will or a durable power of attorney for health care, respectively. Only 9% (95% CI, 7%-11%) offered educational sessions on advance directives and 17% distributed advance directive informational material. Education about cardiopulmonary resuscitation was provided by 27% (95% CI, 23%-30%), but only 3% (95% CI, 2%-4%) provided information on do-not-resuscitate topics. Fifty percent (95% CI, 46%-53%) were in favor of including advance directive education and 49% (95% CI, 45%-52%) favored inclusion of do-not-resuscitate topics into curricula. CONCLUSIONS: Cardiac rehabilitation programs are potentially valuable but not widely used sites for educating patients with cardiac disease about advance directives.

Advance Care Planning↗
PubMed2001

Mutans streptococci--in families and on tooth sites. Studies on the distribution, acquisition and persistence using DNA fingerprinting.

Mutans streptococci (MS) are bacteria showing several cariogenic traits. This thesis is based on the concept that humans acquire MS directly or indirectly from each other. Previous research on the transmission of the bacteria in families has indicated that children acquire MS from their mothers. Just a few studies have included fathers. Diverging results have been presented about spouses acquiring MS from each other. The information on the distribution of MS types at a tooth surface level has been limited. The methods used for identification of MS types have been refined during the years making further studies in the field interesting. The present thesis deals primarily with the distribution of MS in families. Twenty-five Swedish families including a 3-year-old first-born child (I) and 11 corresponding Chinese families (II) were studied. The Swedish families were followed up 2-5 years later (III and IV). Study V deals with the colonization of MS on tooth sites in 13 young adults. MS were isolated from bacterial plaque samples obtained from the teeth of the subjects. Identification of MS types was carried out through DNA analysis methods, REA and RAPD respectively. MS were detected in 11 of the 25 Swedish children. The distribution of MS genotypes in these families indicated that the mothers and individuals outside the family were the sources of MS to the children (I). The distribution of MS genotypes in the Chinese families (II) pointed to the fact that the father played a more pronounced role as MS source compared to in the Swedish families. The intra-familial distribution of MS seemed to be different in the two groups of families with different cultural backgrounds. At the follow-up, genotypes of MS were found again among the MS positive children and their parents. This indicated that genotypes of MS persisted. Even though some alterations in the prevalence of MS genotypes were shown (III). Among the MS negative children some had acquired the bacteria, but most of them remained MS negative by the age of 5-8 years (IV). The father was in some few cases the MS source to the child in the Swedish families (III, IV). Few spouses acquired MS from each other. It is not clear to which extent the parents' salivary levels of MS, caregiver of the child, breast-feeding or antibiotic treatment influenced the acquisition of MS in the groups studied (I-IV). Finally it was shown that several different genotypes of MS colonized a particular tooth site simultaneously. Within each individual the same genotype occurred on two or more tooth sites. Genotypes persisted 4-7 months on their site. The colonization diverged inter-individually in terms of the number and the distribution of MS genotypes on the tooth sites (V).

Adult↗
PubMed1995

Studies on the distribution and characteristics of new mammalian selenium-containing proteins.

It has now been established that the essential effects of selenium in mammals are owing to the presence of several biologically active selenium compounds. Seleno-enzymes identified so far include several glutathione peroxidases and the type 1 iodothyronine de-iodinase. Some other selenoproteins have been sequenced and characterized. After in vivo labelling of rats with 75Se and protein separation using gel electrophoretic methods, more than 25 selenium-containing proteins or protein sub-units were detected. Some of the results of the investigations on these compounds are summarized and discussed here. By determining the pattern in a large number of tissues information on the distribution of the selenium-containing proteins was obtained. Their biological significance is not yet known but several findings indicate that some of these proteins may have important functions, especially in the brain and the endocrine and reproductive organs. More detailed information is already available on a 34 kDa-protein found in the testis and spermatozoa. Studies on the effects of dosage and chemical form of dietary selenium indicated that the tissue levels of the seleno-enzymes are homeostatically controlled and cannot be increased by additional supply. The increase in the tissue selenium observed with high selenium intake was found to be mainly caused by the non-specific incorporation of the element into a large number or proteins. The formation of most of the other selenium-containing proteins has priority over that of the cytosolic and plasma glutathione peroxidases. Thus the selenium requirement, which was calculated for optimum plasma glutathione peroxidase activity, also covers the amounts needed for normal levels of the other biologically important selenium compounds.

Animals↗
PubMed2000

Upgrading legacy systems for the Integrating the Healthcare Enterprise (IHE) initiative.

As technology vendors have adopted standardized communication protocols, including Digital Imaging and Communications in Medicine (DICOM) and Health Level 7 (HL7), interconnectivity between various devices has been simplified. The recent Integrating the Healthcare Enterprise (IHE) initiative will further promote the use of standards for interconnectivity. Until these standards are universally accepted, we must live in a transitional world where some components will communicate without any modification, while others require upgrades to allow them to meet the new standards. In designing and implementing the network at University of California Los Angeles (UCLA) Medical Center, some integration problems were found that are common to the industry. Creating departmental workflow with only a limited number of acquisition devices supporting the DICOM worklist was the initial problem addressed. Although many manufacturers provide this function for their new scanners, upgrading existing equipment is often cost-prohibitive. To ensure the quality of the demographic information in the image data and the workflow of the system, third-party worklist components were required to upgrade the legacy acquisition devices. These worklist components provided a standards-compliant facade on top of the legacy equipment, allowing seamless integration with the remainder of the network. To support the distribution of worklist information and the feedback of procedure status, a bidirectional HL7/DICOM protocol bridge was required. Although many radiology information system (RIS) manufacturers will be providing native DICOM capabilities in future product releases, the majority of current RIS installations have no DICOM functionality. Similar to the legacy scanners, the HL7/DICOM bridge provided a DICOM-compliant facade to the non-DICOM RIS. The additional use of web-based technology for worklist display further extended flexibility of this facade. We have demonstrated standards-compliant facade technology allowing legacy components to operate seamlessly in an IHE environment at a fraction of the cost of upgrading to new equipment.

Computer Communication Networks↗