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At least 1,297 records · Page 72Linked to original sources
PubMed2000

Inaccuracy of clinical phenotyping parameters for hypertensive nephrosclerosis.

BACKGROUND: Multiple studies suggest that hypertension-induced end-stage renal disease (ESRD) is heritable. Identification of nephropathy susceptibility genes absolutely requires accurate phenotyping, but the clinical hypertensive nephrosclerosis (HN) phenotype is poorly characterized. We hypothesized that many patients with HN as the indicated cause of ESRD on the Health Care Financing Administration (HCFA) 2728 form, fail to satisfy stringent HN phenotyping criteria. METHODS: Since renal biopsy documentation of HN is uncommon, clinical parameters for HN phenotype were applied: family history of hypertension, left ventricular hypertrophy, proteinuria <0.5 g/day, and hypertension preceding renal dysfunction (Schlessinger et al., 1994) or urine protein:creatinine (prot:creat) ratio <2.0 and no evidence of other renal diseases (AASK Trial Group, 1997). RESULTS: ESRD patients (n=607, 73% African American, 25% Caucasian) were enrolled in a study to identify HN susceptibility genes. HN was the most common cause of ESRD according to HCFA 2728 forms (37% prevalence). Phenotyping of randomly selected patients with HN from the total cohort revealed that 4/100 subjects satisfied the Schlessinger criteria, and 28/91 African Americans met AASK criteria for HN. From these figures, the adjusted prevalence of HN was only 1.5-13.5%. Of patients that could not be phenotyped for HN, 14 were misdiagnosed, 14 had urine prot:creat >2.0, and insufficient data were available in the remainder. Four patients underwent renal biopsy, but histology from only one was consistent with HN. If the HN phenotype definitions are revised to exclude 'hypertension preceding renal dysfunction', or proteinuria limits, then 44/100 and 39/91 patients respectively satisfy clinical phenotyping parameters for HN. CONCLUSIONS: (i) We provide the strongest evidence to date that HN is less frequent in an ESRD population than commonly assumed if strict clinical criteria are used; many patients clinically diagnosed with HN may have undetected, treatable renal disease from other causes; (ii) relaxing HN phenotype criteria may erroneously include patients with glomerular diseases and secondary hypertension; (iii) reliance on HCFA 2728 diagnoses will confound identification of HN susceptibility genes; (iv) to attain adequate statistical power for genotype analysis, rigorous HN phenotyping will require screening an extremely large number of patients, which can be reasonably accomplished only in a multi-centre trial design.

Black People↗
PubMed2005

Interictal to ictal transition in human temporal lobe epilepsy: insights from a computational model of intracerebral EEG.

In human partial epilepsies and in experimental models of chronic and/or acute epilepsy, the role of inhibition and the relationship between the inhibition and excitation and epileptogenesis has long been questioned. Besides experimental methods carried out either in vitro (human or animal tissue) or in vivo (animals), pathophysiologic mechanisms can be approached by direct recording of brain electrical activity in human epilepsy. Indeed, in some clinical presurgical investigation methods like stereoelectroencephalography, intracerebral electrodes are used in patients suffering from drug resistant epilepsy to directly record paroxysmal activities with excellent temporal resolution (in the order of 1 millisecond). The study of neurophysiologic mechanisms underlying such depth-EEG activities is crucial to progress in the understanding of the interictal to ictal transition. In this study, the authors relate electrophysiologic patterns typically observed during the transition from interictal to ictal activity in human mesial temporal lobe epilepsy (MTLE) to mechanisms (at a neuronal population level) involved in seizure generation through a computational model of EEG activity. Intracerebral EEG signals recorded from hippocampus in five patients with MTLE during four periods (during interictal activity, just before seizure onset, during seizure onset, and during ictal activity) were used to identify the three main parameters of a model of hippocampus EEG activity (related to excitation, slow dendritic inhibition and fast somatic inhibition). The identification procedure used optimization algorithms to minimize a spectral distance between real and simulated signals. Results demonstrated that the model generates very realistic signals for automatically identified parameters. They also showed that the transition from interictal to ictal activity cannot be simply explained by an increase in excitation and a decrease in inhibition but rather by time-varying ensemble interactions between pyramidal cells and local interneurons projecting to either their dendritic or perisomatic region (with slow and fast GABAA kinetics). Particularly, during preonset activity, an increasing dendritic GABAergic inhibition compensates a gradually increasing excitation up to a brutal drop at seizure onset when faster oscillations (beta and low gamma band, 15 to 40 Hz) are observed. These faster oscillations are then explained by the model feedback loop between pyramidal cells and interneurons targeting their perisomatic region. These findings obtained from model identification in human temporal lobe epilepsy are in agreement with some results obtained experimentally, either on animal models of epilepsy or on the human epileptic tissue.

Algorithms↗
PubMed2000

Odontological identification of human remains from mass graves in Croatia.

This paper reports the results and methods of dental identification of 1000 human remains exhumed from mass graves in Croatia up to July 1998. Personal identification of the victims was performed at the Department of Forensic Medicine and Criminology at the School of Medicine in Zagreb. A forensic odontologist participated in the identification process by carrying out the dental identification. A total of 824 victims were positively identified, while 176 victims remained unidentified. Dental identification based on available dental antemortem data was achieved in 25% of the cases. Dental identification based on dental charts was achieved in 35%, on x-rays in 15%, on photographs of teeth in 22%, on interviews in 18%, and on confirmation by odontologists in 10% of the cases. Teeth, in combination with anthropological parameters, age, sex and height, as well as other specific characteristics such as tattoos, personal identification cards, clothes, jewellery and DNA, were helpful for identification of 64% of the victims, but the significance for the identification was not dominant. Only in 11% of the cases was identification achieved by other relevant means and teeth not used at all. Identification procedures in Croatia will continue until another 1700 people who are still missing or kept as prisoners of war since the aggression on Croatia in 1991 are found and/or identified.

Adolescent↗
PubMed1994

New ideas for solving identification and optimal control problems related to biomedical systems.

Many bio-medical models lead to differential systems where some parameters have to be identified from partial observation on the system's solution. For two- or three-compartment models parameters to be identified can be explicitly calculated (when uniqueness is ensured) from the algebraic relation obtained by using classical methods. However, when the number of compartments is greater than three, numerical techniques are necessary. In this work we propose new numerical methods based on Adomian's method for solving identification and optimal control problems associated to biomedical systems.

Algorithms↗
PubMed1974

International reference study on the identification and scoring of human chromosome aberrations. Results of a WHO comparative study.

Chromosome aberrations in human peripheral blood are recognized parameters of cellular damage and are used as indicators of exposure to ionizing radiation and certain chemicals. However, significant interlaboratory variability exists in the results reported from different laboratories. The primary objective of the present study was to examine problems associated with the identification and analysis of chromosome aberrations. Significant interlaboratory variability was found to exist in the analysis of human chromosome spreads for induced interphase aberrations, apparently owing in part to differences in the selection and rejection of spreads for scoring and also in the recognition and classification of various types of aberrations. These differences are reflected in the dose-response relationships for aberrations as well as for damaged spreads. For damaged spreads the scoring variability appears to be relatively small. It is inferred that factors additional to differences in scoring may play a significant role in the large variation in the reported dose-response relationships both for ionizing radiation and for chemically induced aberrations.

Analysis of Variance↗
PubMed2002

[Analysis of benzodiazepine derivative mixture by gas-liquid chromatography].

The analysis of mixture of benzodiazepine derivates (chlordiazepoxide, flunitrazepam, medazepam, nitrazepam, oxazepam and tetrazepam) by gas--liquid chromatography (GLC) in purpose to separate and identify these psychotropic drugs in mixture is presented in this article. The experiment was carried out in vitro, accommodating this method for identification and separation of drugs, isolated from biological objects (blood and urine). Referring to data of annual reports of chemical investigations (1) above-mentioned psychotropic drugs are very frequent among drug intoxication. In most cases they are detected in the mixture of the same or different pharmacological group, and this causes difficulty for separation and identification. The analysis of the mixture was carried out by GLC, which is widely used in practice of forensic-chemical examination. Adsorbents and stationery phases were changed; the conditions and parameters of chromatography were modified, in purpose totally separate preparations in the mixture. For the separation and identification of all three preparation the column packed with Inerton Super with stationary phase 3% OV-17 is suitable. The column temperature-290 degrees C. The mixture of these drugs was excreted from body fluids (blood and urine) in vitro and investigated by GLC under these conditions. The results of investigation were similar.

Anti-Anxiety Agents↗
PubMed1998

Cytotoxicity of urethane dimethacrylate composites before and after aging and leaching.

The in vitro cytotoxicity of urethane dimethacrylate composites cured at different times by visible light and after different aging times and extraction treatments was evaluated using succinic dehydrogenase activity in the mitochondria of a fibroblastic cell line to reflect cell viability. In addition, extractable chemicals associated with cell response were identified. The composite samples were tested untreated, polished, or extracted with water or 75% ethanol-water. Balb/c 3T3 fibroblasts were used as the cell culture system while MTT-formazan production was used as the toxicity parameter. Cell viability was calculated as a percentage of Teflon controls. Identification of the chemicals was measured by extracting the composites with 75% ethanol-water, separating the extract by HPLC, and identifying the fractions with mass spectroscopy. In general, cell viability increased continuously with curing time for differently treated samples at high aging times (288 h) while it decreased when the composites were not aged (0 h). In addition, for 75% ethanol or water-extracted composites, cell viability increased within the first 24 h of aging and reached a plateau after 72 h. Lowest cytotoxicity occurred when the samples were extracted with the 75% ethanol solution. The highest cytotoxic effects were found when the samples were untreated. Slightly reduced cytotoxic effects were seen with polished composites. The results suggest that curing the light-activated composites for a minimum of 150 s and post-curing for 24 h is required to attain comparable biocompatibility with the Teflon control. Removing the oxygen-inhibited layer from these composites decreased the cytotoxicity by 33% while extracting the composites with 75% ethanol-water decreased it by 77%. Chemicals released from the surface accounted for approximately 40% of cellular response while about 60% of the response was due to chemical components released from the bulk. The primary leachable component from the composites was UDMA monomer. Small quantities of 1,6 hexane diol methacrylate, camphoroquinone, and 2,4,6-tritertiarybutyl phenol also were found.

3T3 Cells↗
PubMed2025

Development and Validation an Integrated Deep Learning Model to Assist Eosinophilic Chronic Rhinosinusitis Diagnosis: A Multicenter Study.

BACKGROUND: The assessment of eosinophilic chronic rhinosinusitis (eCRS) lacks accurate non-invasive preoperative prediction methods, relying primarily on invasive histopathological sections. This study aims to use computed tomography (CT) images and clinical parameters to develop an integrated deep learning model for the preoperative identification of eCRS and further explore the biological basis of its predictions. METHODS: A total of 1098 patients with sinus CT images were included from two hospitals and were divided into training, internal, and external test sets. The region of interest of sinus lesions was manually outlined by an experienced radiologist. We utilized three deep learning models (3D-ResNet, 3D-Xception, and HR-Net) to extract features from CT images and calculate deep learning scores. The clinical signature and deep learning score were inputted into a support vector machine for classification. The receiver operating characteristic curve, sensitivity, specificity, and accuracy were used to evaluate the integrated deep learning model. Additionally, proteomic analysis was performed on 34 patients to explore the biological basis of the model's predictions. RESULTS: The area under the curve of the integrated deep learning model to predict eCRS was 0.851 (95% confidence interval [CI]: 0.77-0.93) and 0.821 (95% CI: 0.78-0.86) in the internal and external test sets. Proteomic analysis revealed that in patients predicted to be eCRS, 594 genes were dysregulated, and some of them were associated with pathways and biological processes such as chemokine signaling pathway. CONCLUSIONS: The proposed integrated deep learning model could effectively predict eCRS patients. This study provided a non-invasive way of identifying eCRS to facilitate personalized therapy, which will pave the way toward precision medicine for CRS.

Humans↗
PubMed2005

Atmospheric aerosols: composition, transformation, climate and health effects.

Aerosols are of central importance for atmospheric chemistry and physics, the biosphere, climate, and public health. The airborne solid and liquid particles in the nanometer to micrometer size range influence the energy balance of the Earth, the hydrological cycle, atmospheric circulation, and the abundance of greenhouse and reactive trace gases. Moreover, they play important roles in the reproduction of biological organisms and can cause or enhance diseases. The primary parameters that determine the environmental and health effects of aerosol particles are their concentration, size, structure, and chemical composition. These parameters, however, are spatially and temporally highly variable. The quantification and identification of biological particles and carbonaceous components of fine particulate matter in the air (organic compounds and black or elemental carbon, respectively) represent demanding analytical challenges. This Review outlines the current state of knowledge, major open questions, and research perspectives on the properties and interactions of atmospheric aerosols and their effects on climate and human health.

Aerosols↗
PubMed1993

Forward scatter pulse width signals resolve multiple populations of endosomes.

The technique of pulse width analysis, developed to optimize cell size resolution in cell cycle kinetics, has not previously been applied to small particles such as endosomes. Offset is used to subtract a portion of the beam diameter from forward scatter pulse width signals to optimize visualization and discrimination of small particles. We identify multiple endosomal populations by offset pulse width of light scatter parameters. Specifically, linear forward scatter pulse width measurements reveal at least two populations of endosomes in the rat renal cortex, the rat renal papilla, and the luminal endothelium of the toad urinary bladder. Logarithmically amplified forward scatter pulse width measurements display the full dynamic range of these signals, resolving additional populations not manifest with linear amplification. To confirm that the endosomes observed were resolved from optical and electronic noise, we examined physiological function. The endosomes acidified after supplying ATP to the intrinsic membrane H(+)-ATPase present. Further, electron microscopy of sorted endosomal populations from the toad urinary bladder confirmed identity and homogeneity of the fraction. Flow cytometric analysis of endosomal populations by multiparametric techniques including pulse width analysis of structural parameters and pulse height analysis of fluorescence from entrapped fluorophores allows identification, isolation, and quantification of multiple endosomal populations.

Animals↗
PubMedDate not supplied

Response characteristics of an aquatic biomonitor used for rapid toxicity detection.

The response characteristics of an aquatic biomonitor that detects toxicity by monitoring changes in bluegill (Lepomis macrochirus Rafinesque) ventilatory and movement patterns were evaluated in single chemical laboratory studies at concentrations near the 96-h LC(50) concentration and at the EILATox-Oregon Workshop in sequential tests of multiple unknown samples. Baseline data collected prior to exposure allows each fish to serve as its own control. When at least 70% of exposed fish exhibit ventilatory or movement parameters significantly different from baseline observations, a group alarm is declared. In the laboratory studies, the aquatic biomonitor responded to the majority of chemicals at the 96-h lc(50) within an hour or less, although substantially higher response times were found for malathion and pentachlorophenol. Workshop tests of single chemical concentrations presented as blind samples were consistent with the laboratory test results. There were no alarms under control conditions in any test. Although data are limited, the aquatic biomonitor appears to respond more rapidly to chemicals causing membrane irritation, narcosis or polar narcosis than to acetylcholinesterase inhibitors or oxidative phosphorylation uncouplers. All four monitored parameters (ventilatory rate, cough rate, ventilatory depth and movement) contributed to identification of first alarms at acutely toxic levels. Understanding these response patterns can be useful in data interpretation for biomonitor applications such as surface water monitoring for watershed protection, wastewater treatment plant effluent monitoring or source water monitoring for drinking water protection.

Animals↗
PubMed2001

A Multipurpose Instrument To Measure the Vitreous Properties of Charged Colloidal Solids.

We present a new high-precision light-scattering setup to study the properties of colloidal solids. It combines static light scattering, dynamic light scattering, and torsional resonance spectroscopy with a flexible and reliable preparational procedure. All three experiments can be performed quasi-simultaneously on the same mechanically undisturbed sample. Thus, unequivocal identification of glassy behavior in a comprehensive characterization dependent on interaction parameters becomes possible. A detailed description of the mechanics is given. We thoroughly tested the new apparatus on dilute colloidal samples and against commercial reference instruments. We performed a first systematic series of experiments on near index matched charged particles, varying the packing volume fraction between 0.006 and 0.11. The results indicate a new route into the glassy state different from that observed in hard-sphere systems. The range of applications, accuracy, limitations, and possible extensions of the technique are discussed. Copyright 2001 Academic Press.

Journal Article↗
PubMed1999

Molecular screening of potential HNPCC patients using a multiplex microsatellite PCR system.

Microsatellite instability (MSI) is a molecular hallmark of the H ereditary N on- P olyposis C olorectal C ancer (HNPCC) syndrome occurring in about 80-90% of the tumours and also in sporadic tumours of different organs, albeit at lower frequency. Highly unstable colorectal tumours (MSI-H) have different histopathological features and tend to have a better prognosis compared to neoplasms without (MSS) or with low levels of microsatellite instability (MSI-L). Since MSI classification allows the identification of potential HNPCC patients and might represent a valuable diagnostic parameter an increasing demand for high-throughput microsatellite analysis will arise. Therefore, we have adapted five diagnostic microsatellites, m(odified) ACTC, mBAT26, mD5S107, mD5S406 and mD13S153, to allow coamplification. Using this multiplex polymerase chain reaction (PCR) system 29 colorectal tumour tissues with known MSI status could be unambiguously identified as MSI-H (13 cases) or MSI-L/MSS (16 cases). Highly unstable colorectal tumour detection frequency of individual markers reached 77% (mD5S406), 85% (mACTC), 85% (mD5S107), 92% (D13S153) and 100% (mBAT26) showing similar sensitivity but improved specificity as compared with a microsatellite reference panel. In a prospective analysis of 31 colorectal tumours, the multiplex PCR system identified five MSI-H cases. Multiplex MSI PCR is a time saving and cost-effective method not restricted to specific technical equipment and applicable to a variety of microsatellite-based genotyping approaches.

Colorectal Neoplasms↗
PubMed1992

Immunobiology of experimental leishmaniasis.

Self-cure versus uncontrolled disease progression in experimental murine cutaneous leishmaniasis depends upon a delicate interplay among various activated cells of the host's immune system. Susceptibility or resistance to infection with Leishmania major is correlated with the ability of different inbred strains of mice to produce the characteristic spectra of lymphokines upon infection. Appropriate experimental interventions now allow the modulation of these responses, providing the possibility to render genetically susceptible mice resistant to infection and, vice versa, to cause genotypically "healer" strains to express a "non-healer" phenotype. These experimental manipulations have proven to be powerful tools in the dissection of the underlying immune mechanisms and cellular parameters responsible for susceptibility and resistance, and will perhaps allow the identification of molecules of parasite origin that induce deleterious immune responses to infection with Leishmania, and thus to exclude them from future vaccines. More importantly, rational immune intervention could permit the diversion of established host-damaging immune responses to host-protective immunization.

Animals↗
PubMed1990

A computer system for the identification of the cerebrospinal compensatory model.

A computer system, based on IBM PC, was designed for the cerebrospinal compensatory model identification. The intracranial pressure (ICP) signal, registered during the lumbo-lumbar infusion test is analyzed by means of the spectral analysis algorithm in order to measure precisely the pulse wave amplitude. The amplitude and the mean ICP level, calculated repetetively within the period of about 8 seconds, are stored on the disk and form the basis for further model identification. Three different methods of identification were applied. They enable one to estimate the fundamental model parameters, such as: resistance to the cerebrospinal fluid resorption, pressure-volume index, baseline pressure, rate of formation of the cerebrospinal fluid. Statistical evaluation of the results of the infusion test analysis obtained by means of the system described in two groups of hydrocephalic patients (children and adults) is presented.

Adult↗
PubMed1994

Analysis of protein glycosylation by mass spectrometry.

There is a growing pharmaceutical market for protein-based drugs for use in therapy and diagnosis. The rapid developments in molecular and cell biology have resulted in production of expression systems for manufacturing of recombinant proteins and monoclonal antibodies. These proteins are glycosylated when expressed in cell systems with glycosylation ability. For glycoproteins intended for therapeutic administration it is important to have knowledge about the structure of the carbohydrate side chains to avoid cell systems that produce structures, which in humans can cause undesired reactions, e.g., immunological and unfavorable serum clearance rate. Structural analysis of glycoprotein oligosaccharides requires sophisticated instruments like mass spectrometers and nuclear magnetic resonance spectrometers. However, before the structural analysis can be conducted, the carbohydrate chains have to be released from the protein and purified to homogeneity, and this is often the most time-consuming step. Mass spectrometry has played and still plays an important role in analysis of protein glycosylation. The superior sensitivity compared to other spectroscopic methods is its main asset. Structural analysis of carbohydrates faces several problems, however, due to the chemical nature of the constituent monosaccharide residues. For oligosaccharides or glycoconjugates, the structural information from mass spectrometry is essentially limited to monosaccharide sequence, molecular weight, an only in exceptional cases glycosidic linkage positions can be obtained. In order to completely establish an oligosaccharide structure, several other structural parameters have to be determined, e.g., linkage positions, anomeric configuration and identification of the monosaccharide building blocks. One way to address some of these problems is to work on chemical pretreatment of the glycoconjugate, to specifically modify the carbohydrate chain. In order to introduce specific modifications, we have used periodate oxidation and trifluoroacetolysis with the objective of determining glycosidic linkage positions by mass spectrometry.

Acetylation↗
PubMed2006

Guidelines for clinical applications of spatio-temporal gait analysis in older adults.

Quantifying spatio-temporal gait parameters in stationary and ambulatory geriatric settings may aid the early identification of potential fallers, as well as the documentation of illness-specific gait disorders and intervention-related changes in rehabilitative medicine. Bringing gait analysis out of the laboratory and into a clinical setting is the goal of the European GAITRite network group, initiated in 2003 in Geneva. To enhance reproducibility of gait measures and for better comparability of outcomes in clinical environments, a consensus on data collection was formulated and presented at the 2nd European GAITRite Meeting in Marseilles. The guidelines presented here are intended to facilitate network collaborations and to provide guidance to clinicians who wish to implement spatio-temporal gait analysis in clinical settings.

Accidental Falls↗
PubMed1984

Processing and analysis techniques for brain-stem auditory evoked potentials with localization of brain-stem lesions.

A computer assisted method of exact automatic measurement of BAEPs, mainly for the purpose of localization of brain-stem lesions, is described. The method presents analogue curves with superimposed confidence regions for the amplitudes and peak latencies of separate waves. The numerical output presents peak latencies, amplitudes, interpeak time intervals and central conduction times, all with normative values (60 healthy subjects), and +/- 2 and +/- 3 S.D. intervals and automatic labelling of pathological parameters (outside the chosen statistical limits). With the exception of the identification of separate waves in the often greatly distorted pathological BAEP the whole processing and display of the results are fully automatic.

Brain Diseases↗