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At least 595 records · Page 33Linked to original sources

Anterior-posterior stability in partially conforming condylar knee replacement.

The purpose of the study was to estimate the anterior-posterior displacements that would occur with total knee prosthetic designs of different sagittal radii under functional conditions. A key question was whether some designs provided excessive constraint. Patients who had different total knee prosthetic designs were tested in a special rig where the AP drawer was measured under loaded and unloaded conditions. These same designs of total knee prostheses were then tested in a rig under different conditions of compressive and shear loads. Using these experiments as verification, a theoretical treatment was developed to predict the AP displacement for different activities. It was concluded that designs with low to moderate conformity required soft tissue restraint under more strenuous activities, or where high shear forces occurred under low compressive loads. Designs of moderate to high conformity could be fully self-stabilizing under all realistic conditions. However, for all designs, the AP displacement was only a few millimeters under functional loads, indicating that special care must be taken during surgery to avoid conflict between the condylar surfaces and the retained cruciate ligaments so that restriction of motion and excessive wear do not occur.

Aged↗

Bioinformatic identification and characterization of new members of short-chain dehydrogenase/reductase superfamily.

With about 60 genes known in the human genome, short-chain dehydrogenases/reductases (SDRs) form a large gene family with important implications for medicine. They are known to be involved in carcinogenesis (e.g. breast and prostate cancer) as well as in metabolic and degenerative defects such as the pathogenesis of Alzheimer's disease, osteoporosis and diabetes. Uncharacterized SDRs are thus potential candidates for many monogenic and multifactorial human diseases. The identification and functional analysis of such SDR enzymes is therefore the primary goal of the study leading to new targets for drug development. In all taxa (bacteria, plants, insects, vertebrates), members of SDR superfamily are known. Up to now, there are several thousand members annotated many of which have not been characterized biochemically with regard to enzymatic activity, substrate specificity, or subcellular localization. We bioinformatically identified 250 vertebrate candidate genes belonging to the SDR superfamily using the BioNetWorks software SDR finder. The number was reduced to 95 after continuative analysis, including manual SDR motif verification and focus on human, rat and murine enzymes. Here, we present several new mammalian SDRs that were clustered into several enzymatically different groups by detailed phylogenetic analyses. Furthermore, characteristic mRNA expression patterns were identified for some of these genes by a recently developed in silico Northern blot method supporting their putative functions in retinoid, steroid, sugar and other metabolic pathways.

Amino Acid Sequence↗

Contextualism and the development of effective prevention practices.

Widespread and effective implementation of research-based prevention practices will be facilitated by the explicit adoption of a functional contextualist framework for prevention research. Such a framework has as its central goal predicting and influencing behavior and cultural practices. Research within this framework is evaluated in terms of its ability to contribute to that goal. As a result, it contributes directly to the ultimate goals of prevention science-affecting the incidence and prevalence of problems in populations. The approach contrasts with the mechanist framework, which is implicit in much behavioral science research. The mechanist framework has as its truth criterion the predictive verification of models of the interrelationships among variables. Such models can-but need not-identify manipulable variables that can be exploited to affect problems of interest. Such models require the inclusion of multiple cases for testing and this requirement may impede the tendency of scientists to work with a single school or community. Functional contextualism is suited to the study of the individual case. It provides a framework within which researchers can more readily collaborate with practitioners in the development and further evaluation of practices within the settings where practitioners will ultimately use those practices.

Models, Organizational↗

Analysis of the early blood kinetics of 99mTc-GSA and its verification: new one-compartment model and regression equation.

Technetium-99m-galactosyl human serum albumin (99mTc-GSA) is a radiopharmaceutical that binds to asialoglycoprotein receptors in the hepatocyte membrane; the level of 99mTc-GSA accumulation in the liver correlates well with the parameters of hepatic function tests. We hypothesized that the early blood kinetics of 99mTc-GSA could be described by a simple one-compartment model expressed as an offset + a monoexponential function (y=y0 +Ae(-alpha)t). The aims of this study were to assess the validity of this hypothesis using sequentially measured blood levels of 99mTc-GSA, which were approximated by a regression expression, and to analyse the regression equation. 99mTc-GSA levels were measured in blood samples collected from 30 patients with liver disease. From sequential changes in radioactivity up to 30 min after injection, a regression equation expressed as an offset+ a monoexponential function was calculated and evaluated by multiple correlation coefficients and absolute deviations (% error). The liver uptake rate 15 min after injection of 99mTc-GSA (liver uptake rate 15, UTR 15) was calculated from the regression equation in each case. The respective relationships of this parameter to the coefficient [A] and gradient [alpha] were evaluated. In all cases, the measured values of radioactivity in blood samples could be fitted to an offset + a monoexponential function. The validity of our hypothesis was supported by examining regression equations calculated from blood 99mTc-GSA levels. Analysis of the regression equations suggested a potential for a new index of hepatic functional reserve.

Algorithms↗

Is it possible to assess disease activity of inflammatory bowel disease with scintigraphy?

99mTc-HMPAO-leukocyte scintigrams were compared with the activity index (AI) of Van Hees in 145 inflammatory bowel disease (IBD) patients. Labelling of leukocytes with 99mTc-HMPAO was less time-consuming and less laborious than 111In-labelling of granulocytes; in addition, the radiation dose for the patient is lower and the shorter acquisition time allows multiple views. In a previous comparative study 99mTc-leukocytes proved superior to 111In-granulocytes in detecting active IBD. The present study shows that a positive AI (> 125) is associated with a positive 99mTc-leukocyte scintigram (40 pts); a negative 99mTc-leukocyte scintigram is only found in patients with a negative AI (27 pts). In 30 out of 78 patients with an AI < or = 125 and a positive scintigram these positive results were confirmed by radiological and/or endoscopic examinations, but in the remaining 48 patients verification of the scintigraphic result was prohibited due to the absence of other confirmative examinations within 1 month of scintigraphy. In our view 99mTc-leukocyte scintigraphy may well be the gold standard for functional assessment of inflammation intensity and localization in IBD patients.

Granulocytes↗

Effects of diabetes and steroids on fracture healing.

Fracture healing is largely controlled by local regulatory interactions among cells and tissues near the site of injury; however, many systemic hormones including insulin, the glucocorticoids, and the gonadal steroids also can influence the course of tissue repair, particularly in the case of pathologic hormone excess or deficiency. Using well-defined animal models, recent studies have established that deficiencies in insulin and estrogen impair fracture healing, but data from this type of experiment are limited. Still, the similarities between morphogenetic events in fracture healing and those found in normal bone development and remodeling suggest that testable predictions can be made concerning hormonal effects on the progress of fracture healing. One concept that has received some direct experimental support in fracture healing model studies is that systemic hormones exert pleiotropic effects on callus tissue by regulating the expression and activity of local growth factors. Further verification of this and other predicted hormone effects should increase our understanding of the fundamental mechanisms underlying fracture repair, and may aid development of means to improve fracture healing in states of altered endocrine function.

Androgens↗

Clinical pharmacy activities: a quantitative assessment at Sunnybrook Medical Centre.

Levels of clinical pharmacy activity were assessed at Sunnybrook Medical Centre using levine et al's concept of Patient Care Units. Data from pharmacist-initiated log sheets (for two four-week periods) were collated and described under the headings of: "Average Clinical Time Per Day", "Number of Specific Clinical Encounters Per Month", "Average Percentage of Total Clinical Time Per Encounter", and "Average Time Per Specific Clinical Encounter". It was noted that only 21.7 to 26.0% of working time was spent on clinical interactions and that many of these activities did not involve patients. For example, clinical non-distributive interactions with professionals (other than physicians or nurses) and attendance at pharmacy educational functions, accounted for the largest portion of clinical time. Most of the patient encounters that did occur consisted of the indirect activity of chart review, instead of the more direct-discharge interviews, allergy verifications, and medication histories, it was apparent from the log sheet results that there was an individual prioritization of clinical activities by the Sunnybrook pharmacists. However, a departmental assumption that direct patient encounters had priority was not evident.

Hospital Bed Capacity, 500 and over↗

Antioxidants--clinical aspects.

Interest in nutrition and food consumption in advanced countries has become an important instrument of active care for maintaining the population's health. Basic orientation in food composition and in topical knowledge about the effectiveness of individual nutrients in the human organism form an indispensable part of nutrition and health consciousness and it can significantly facilitate and improve activity in both professionals and non-professionals, or it can correct some subjective opinions and deep-rooted imaginations. At the end of the last century progress in molecular biological research led to better knowledge about previously unknown functions of nutrients in the metabolism and also knowledge about relationships among the individual nutrients. The interest of research institutes was concentrated on selected nutrient groups and also on vitamins. Attention was focused on verification of the role of vitamin E and beta carotene in strengthening the antioxidative capacity of the organism and immunity system as prevention against degenerative diseases, atherosclerosis and tumorous diseases. Attention was attracted to the fact that folacin acts preventively against defects of the neural tube and against hyperhomocysteinemia as an independent atherosclerosis risk factor. Also the data about the organism's needs, for example vitamins, are mostly not quite complete, especially in the sphere of detailed knowledge of their preventive effect concerning the so-called civilization diseases, their use in the organism and the reaction of the organism to their insufficient or redundant supply.

Antioxidants↗

[Computerization and the importance of information in health system, as in health care resources registry].

The possibilities of creating a health care resources registry and its operating in Croatia as well as the importance of information in health system are described. At the Croatian Institute of Public Health, monitoring of human resources is performed through the national Health Workers Registry. It also covers basic data on all health units, bed capacities of health facilities included. The initiated health care computerization has urged the idea of forming one more database on physical resources, i.e. on registered medical devices and equipment, more complete. Linking these databases on health resources would produce a single Health Care Resources Registry. The concept views Health Care Resources Registry as part of the overall health information system with centralized information on the health system. The planned development of segments of a single health information system is based on the implementation of the accepted international standards and common network services. Network services that are based on verified Internet technologies are used within a safe, reliable and closed health computer network, which makes up the health intranet (WAN--Wide Area Network). The resource registry is a software solution based on the relational database that monitors history, thus permitting the data collected over a longer period to be analyzed. Such a solution assumes the existence of a directory service, which would replace the current independent software for the Health Workers Registry. In the Health Care Resources Registry, the basic data set encompasses data objects and attributes from the directory service. The directory service is compatible with the LDAP protocol (Lightweight Directory Access Protocol), providing services uniformly to the current records on human and physical resources. Through the storage of attributes defined according to the HL7 (Health Level Seven) standard, directory service is accessible to all applications of the health information system. Directory service does not follow the history of attribute changes, and is optimized for a large number of authorizing inquiries. With it, one follows the following objects and attributes: persons, groups of people (patients, physicians, other personnel), roles (right of access and administrator permissions), organizational units, unit locations, devices and services (according to the list of services and procedures). One can add to the Health Care Resource Registry such attributes as are nonessential for inclusion in the directory service, but are of public health value. Authentication, authorization and digital signature are done by means of Smart Cards, which are used as protective elements against access to system functions, and simultaneously as a physical medium for the storage of the official certificate with which documents are signed digitally. As FINA (state financial control agency) has completed a system for certificate issuance and verification, the option of official digital signature is also available as a computer network service. Any changes taking place in the directory service are transferred by XML messages to a separate part of the Registry that reads them and automatically modifies records in the relational database. Because data input and data changes are made in health units, this makes the data updated and directly connected with health working operations. This avoids all one-time data collection campaigns using form filling about the devices and equipment in the future. As it is very difficult to monitor from a central standpoint how accurate and update the information is, it is necessary to delegate the permissions and duties associated with making changes to the directory service. By this organizational setup, the time needed to ensure data quality control is reduced. In the case described, the Health Care Resource Registry becomes an indicator of change, acquiring certain characteristics of an analytical system. An analysis of topical data renders possible proactive action and makes more effective the planning and utilization of available resources. Providing answers on the current data quickly could also be important to solution-seeking in emergencies. The present proposal to establish the Registry is intended to facilitate the future process of planning and striking a balance between investments in human and physical resources. For health expenditure control, having reliable information related to the use and purchase of new medical technology is particularly important. World Health Organization and European Union have also emphasized the need to develop new indicators in this area.

Croatia↗

"Second wind" during inspiratory loading.

Five human volunteers breathed through an inspiratory register to achieve a transdiaphragmatic pressure (Pdi) of 42-45% of the maximum, until fatigue. During the period of resistive breathing all subjects experienced at least one episode of a sudden feeling of relaxation and relief from dyspnea, i.e., "second wind." These episodes were accompanied by a sudden decrease in the neural stimulation to the diaphragm as reflected in the electromyogram (EMG). Changes in lung volume or chest configuration were eliminated as was recruitment of accessory muscles of inspiration during the "second wind"; thus, there appeared to be a change in the contractile function of the diaphragm such that the same force (Pdi) was achieved with less neural input. These results indicate that the phenomenon of "second wind" has physiologic correlates and may be subject to experimental verification and manipulation.

Adult↗

[Video-thoracoscopic surgery].

The experience in application of 24 videothoracoscopical operations in diseases and traumatic injuries of the organs of thoracic cavity (15-diagnostic and 9-curative ones) is reviewed. Histological verification of the diagnosis after the operative procedures was obtained in all 15 patients. The technique of TV thoracoscopic operations is outlined. Postoperation period in patients ran well, there were no substantial disturbances in function of external breathing, motor activity has restored on the second day after the operation.

Carcinoma, Squamous Cell↗

Microarray comparison of normal and W/Wv mice in the gastric fundus indicates a supersensitive phenotype.

Interstitial cells of Cajal (ICC) have been identified in specific areas throughout the smooth musculature of the gastrointestinal (GI) tract. Located within the circular and longitudinal muscle layers of the gastric fundus lies a specific type of ICC, termed "intramuscular" ICC or IC-IM. The principal function of this cell type is to act as "mediators of excitatory and inhibitory enteric neurotransmission." The functional role of these cells has been investigated using W/W(v) mutant mice that specifically lack IC-IM, resulting in disrupted enteric neurotransmission. The aim of the present study was to investigate differential gene expression in W/W(v) mutant mice, from the tunica muscularis of the gastric fundus using a mouse cDNA microarray containing 1,081 known genes. Verification of the microarray data was attained using real-time "quantitative" PCR (qPCR). Of the 1,081 arrayed genes, 36 demonstrated differential expression by >2-fold in the W/W(v) mice. An agreement rate of 50% (7 of 14 tested) was obtained using qPCR. Of the seven confirmed changes in expression, several were indicative of a supersensitive phenotype, observed in denervation models. Expression of several putative neurotransmitter receptors including P2Y, the receptor for the inhibitory neurotransmitter ATP, was upregulated. The functional role of the P2Y receptor was also investigated using electrophysiological recordings. These results offer a new insight into the molecular changes that occur in W/W(v) fundic smooth muscle and may also provide novel information with regard to the importance of IC-IM in enteric neurotransmission.

Animals↗

[Effect of bronchial reactivity on the whole-body plethysmographic inhomogeneity parameter REmax/RE0 and its value in the early diagnosis of chronic nonspecific lung diseases].

Examinations performed with the help of the body-plethysmographic inhomogeneity parameter REmax/RE0 prove the close connection between the development of chronic unspecific pulmonary diseases and the appearance of disturbances of the ventilatory distribution. The functional disturbance metioned is further increased by the bronchial provocation and may partly be demonstrated in a characteristic way also in inconspicuous initial findings. The body-plethysmographic inhomogeneity parameter REmax/RE0 is, however, not suited for the early diagnosis of chronic unspecific pulmonary diseases, since with its help the verification of disturbances of the ventilatory distribution is successful only then, when the total resistance is already increased. For the final judgment of the aptitude of the bronchial reactivity test for the increase of the valency of methods of the distribution analysis in the early diagnosis further examinations are necessary.

Adolescent↗

The verification of an inverse problem in radiation therapy.

The inverse problem in radiation therapy presents a solution for a fluence distribution based on the specification of a region of dose in a patient. We show results for one such solution based on the inversion of an integral over a function of the fluence profile of a rotating beam. We use Monte Carlo methods and numerical integrations to evaluate dose distributions obtained with the inverse method and show the limitations of this theoretical approach. Our results show that dose to a single circular region at an arbitrary position in a 2-dimensional volume can be calculated. Uniform dose to arbitrarily shaped regions cannot be calculated with this formalism, although practical solutions can still be obtained.

Humans↗

Accounting for nonignorable verification bias in assessment of diagnostic tests.

A "gold" standard test, providing definitive verification of disease status, may be quite invasive or expensive. Current technological advances provide less invasive, or less expensive, diagnostic tests. Ideally, a diagnostic test is evaluated by comparing it with a definitive gold standard test. However, the decision to perform the gold standard test to establish the presence or absence of disease is often influenced by the results of the diagnostic test, along with other measured, or not measured, risk factors. If only data from patients who received the gold standard test were used to assess the test performance, the commonly used measures of diagnostic test performance--sensitivity and specificity--are likely to be biased. Sensitivity would often be higher, and specificity would be lower, than the true values. This bias is called verification bias. Without adjustment for verification bias, one may possibly introduce into the medical practice a diagnostic test with apparent, but not truly, high sensitivity. In this article, verification bias is treated as a missing covariate problem. We propose a flexible modeling and computational framework for evaluating the performance of a diagnostic test, with adjustment for nonignorable verification bias. The presented computational method can be utilized with any software that can repetitively use a logistic regression module. The approach is likelihood-based, and allows use of categorical or continuous covariates. An explicit formula for the observed information matrix is presented, so that one can easily compute standard errors of estimated parameters. The methodology is illustrated with a cardiology data example. We perform a sensitivity analysis of the dependency of verification selection process on disease.

Aged↗

Assessment of thyroid function with hormone assays.

Measurement of serum thyroid hormone and TSH levels provide diagnostic information in the majority of patients with thyroid dysfunction. The test strategy in hyperthyroidism differs from that in hypothyroidism. Serum T4 is a good test for hyperthyroidism in patients with normal thyroid hormone-binding protein levels. When binding proteins are abnormal serum free T4 is a much more accurate test for hyperthyroidism than serum T4. Serum T3 and the TSH response to TRH are useful tests for the early diagnosis of hyperthyroidism. Serum TSH is a very sensitive indicator of primary hypothyroidism rising already at the subclinical stage of the disease. Serum T4 and free T4, but not serum T3, are useful for the verification of clinical hypothyroidism. Determination of the TRH-stimulated TSH level is important for the differential diagnosis of pituitary and hypothalamic hypothyroidism. It is imperative to recognize that thyroid tests are often abnormal in various non-thyroidal diseases and that administration of drugs can affect these tests. Serum rT3 is of some value for the assessment of thyroid function in patients with non-thyroidal disease.

Humans↗

Integration of functional magnetic resonance imaging supported by magnetoencephalography in functional neuronavigation

OBJECTIVE: In this study, the intraoperative visualization of functional data provided by functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) leading to functional neuronavigation is demonstrated in surgery around the motor strip. METHODS: In seven patients with lesions adjacent to the central region, fMRI was performed with a 1.5-Tesla magnetic resonance system, using axial echo-planar imaging with a motor and a sensory task. Somatosensory and motor evoked fields were recorded with a biomagnetometer. fMRI and MEG were matched to an anatomic three-dimensional magnetic resonance image set by a contour fit. Then this three-dimensional image data set was transferred to the navigation microscope and displayed in the eyepieces of the microscope during surgery. Additionally, intraoperative recording of somatosensory evoked potentials was performed for verification of the central sulcus. RESULTS: In all cases, the projection of fMRI and MEG data into the operating viewing field allowed easy identification of the central region, which was confirmed by phase reversal of somatosensory evoked potentials in each case. fMRI and MEG measurements yielded corresponding results in each patient. CONCLUSION: Functional neuronavigation with integration of fMRI and MEG allows the fast identification of eloquent brain areas. The widespread availability of fMRI will result in a broad availability of functional neuronavigation, which will, in turn, contribute to the successful surgery of lesions in eloquent brain areas with lower morbidity.

Journal Article↗