SEARCH · PubMed Health

Results for “tracking methods”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources

PubMed2001

Mechanics and multiple-particle tracking microheterogeneity of alpha-actinin-cross-linked actin filament networks.

Cell morphology is controlled by the actin cytoskeleton organization and mechanical properties, which are regulated by the available contents in actin and actin regulatory proteins. Using rheometry and the recently developed multiple-particle tracking method, we compare the mechanical properties and microheterogeneity of actin filament networks containing the F-actin cross-linking protein alpha-actinin. The elasticity of F-actin/alpha-actinin networks increases with actin concentration more rapidly for a fixed molar ratio of actin to alpha-actinin than in the absence of alpha-actinin, for networks of fixed alpha-actinin concentration and of fixed actin concentration, but more slowly than theoretically predicted for a homogeneous cross-linked semiflexible polymer network. These rheological measurements are complemented by multiple-particle tracking of fluorescent microspheres imbedded in the networks. The distribution of the mean squared displacements of these microspheres becomes progressively more asymmetric and wider for increasing concentration in alpha-actinin and, to a lesser extent, for increasing actin concentration, which suggests that F-actin networks become progressively heterogeneous for increasing protein content. This may explain the slower-than-predicted rise in elasticity of F-actin/alpha-actinin networks. Together these in vitro results suggest that actin and alpha-actinin provides the cell with an unsuspected range of regulatory pathways to modulate its cytoskeleton's micromechanics and local organization in vivo.

Actin Cytoskeleton↗

PubMed2005

[Status and perspectives of non invasive cell tracking].

The interaction of different cells is an important regulator in the development of many diseases, including cancer. Some cells are recruited directly from the local tissue environment, others reach the pathological focus via the circulation. Using non-invasive cell tracking methods, the distribution and migration of labeled cells can be studied in experimental animal models, and the role of these cells on the pathogenesis of disease can thus be elucidated. Scintigraphy and SPECT, and especially MRI and optical imaging, are frequently used for this purpose. Studies are mostly performed with macrophages and granulocytes (inflammatory cells), which accumulate in nephritis, encephalitis, and tumors. At present, the understanding of progenitor cell migration and differentiation is gaining increasing interest in neurological disorders (for example Parkinson's disease) and in cardiac diseases (for example myocardial infarction). Non-invasive cell tracking is already established in basic research; in the future, a clinical application of cell tracking is foreseeable in the framework of cell therapy.

Granulocytes↗

PubMed2005

Automatic mammary duct detection in 3D ultrasound.

This paper presents a method for the initial detection of ductal structures within 3D ultrasound images using second-order shape measurements. The desire to detect ducts is motivated in a number of way, principally as step in the detection and assessment of ductal carcinoma in-situ. Detection is performed by measuring the variation of the local second-order shape from a prototype shape corresponding to a perfect tube. We believe this work is the first demonstration of the ability to detect sections of duct automatically in ultrasound images. The detection is performed with a view to employing vessel tracking method to delineate the full ductal structure.

Algorithms↗

PubMed1999

Comparison of lethality, reproduction, and behavior as toxicological endpoints in the nematode Caenorhabditis elegans.

This study describes a new approach for assessing behavioral changes following toxicant exposure and compares the method to other common endpoints used in environmental toxicology. The nematode Caenorhabditis elegans was exposed to a range of ethanol concentrations to determine its effect on survival, reproduction and behavior. Each endpoint was evaluated for its sensitivity by comparing LC50, RC50 (concentration at which there is a 50% reduction in number of offspring as compared to controls), and BC50 (concentration at which there is a 50% reduction in movement as compared to controls) values for ethanol exposure. Worms showed 24-h lethality at concentrations of ethanol in the range of 83 g/L to 99 g/L. Reproduction in C. elegans was estimated by counting the number of off-spring after 3 d of exposure, which decreased with the increase in ethanol concentration from 8 g/L to 71 g/L. Behavior was quantified by using a new computer tracking method, which can simultaneously assess hundreds of nematodes and provides several behavioral parameters in real time. Worms showed some hyperactivity (increased movement) at very low ethanol concentrations (0.8 g/L and 2.4 g/L) and a decrease in movement at higher ethanol concentrations (4 g/L to 40 g/L). A comparison for sensitivity between the three endpoints was performed. Behavior and reproduction responses were found to be similar and, as expected, both are much more sensitive indicators of toxicity than lethality. The advantages and disadvantages of the computer tracking system are discussed.

Animals↗

PubMed2002

Segmentation and tracking of migrating cells in videomicroscopy with parametric active contours: a tool for cell-based drug testing.

This paper presents a segmentation and tracking method for quantitative analysis of cell dynamics from in vitro videomicroscopy data. The method is based on parametric active contours and includes several adaptations that address important difficulties of cellular imaging, particularly the presence of low-contrast boundary deformations known as pseudopods, and the occurence of multiple contacts between cells. First, we use an edge map based on the average intensity dispersion that takes advantage of relative background homogeneity to facilitate the detection of both pseudopods and interfaces between adjacent cells. Second, we introduce a repulsive interaction between contours that allows correct segmentation of objects in contact and overcomes the shortcomings of previously reported techniques to enforce contour separation. Our tracking technique was validated on a realistic data set by comparison with a manually defined ground-truth and was successfully applied to study the motility of amoebae in a biological research project.

Algorithms↗

PubMed2005

Echolocation call intensity in the aerial hawking bat Eptesicus bottae (Vespertilionidae) studied using stereo videogrammetry.

Aerial hawking bats use intense echolocation calls to search for insect prey. Their calls have evolved into the most intense airborne animal vocalisations. Yet our knowledge about call intensities in the field is restricted to a small number of species. We describe a novel stereo videogrammetry method used to study flight and echolocation behaviour, and to measure call source levels of the aerial hawking bat Eptesicus bottae (Vespertilionidae). Bats flew close to their predicted minimum power speed. Source level increased with call duration; the loudest call of E. bottae was at 133 dB peSPL. The calculated maximum detection distance for large flying objects (e.g. large prey, conspecifics) was up to 21 m. The corresponding maximum echo delay is almost exactly the duration of one wing beat in E. bottae and this also is its preferred pulse interval. These results, obtained by using videogrammetry to track bats in the field, corroborate earlier findings from other species from acoustic tracking methods.

Animals↗

PubMed1987

Quantification of blood pressure tracking of children by tracking index: the Shimane Heart Study.

The tracking of systolic blood pressure (SBP) was analyzed in a cohort of children. The study population consisted of 1009 Japanese children in Izumo City, a rural community in the northwest of Honshu. There were 252 subjects in cohort (C)-1, 235 in C-2, 286 in C-3, 131 in C-4 and 105 in C-5. Follow-up periods were from 6 to 9 years of age in C-1, 9 to 12 in C-2, 12 to 15 in C-3, 6 to 12 in C-4 and 9 to 15 in C-5. BP was measured by conventional method. Tracking index (TI) was calculated as follows: TI = (2x + y - z)/N/.24; x, y and z are numbers of subjects who remained at the same quintile, who moved to the next quintile and who moved to a remote quintile, respectively; N = x + y + z; TI becomes 1.0 when SBP changes randomly. SBP tracking was apparent in both sexes of C-1 (TI = 2.4 in boys, 2.5 in girls), in girls of C-2 (TI = 3.5), in both sexes of C-3 (TI = 3.2 in boys, 2.7 in girls) and in girls of C-4 (TI = 4.1) and C-5 (TI = 3.3). TI agreed well with the tracking phenomena visualized by distribution bar graph. We conclude that TI can assess the degree of tracking quantitatively and can be applied to analysis of the tracking phenomena of BP and its related factors.

Blood Pressure↗

PubMed2006

Development of a Scorpion probe-based real-time PCR for the sensitive quantification of Bacteroides sp. ribosomal DNA from human and cattle origin and evaluation in spring water matrices.

Spring water from alpine catchments are important water resources but they can be vulnerable against faecal contamination. Potential faecal contamination sources are wildlife populations, pasturing activities, or alpine tourism. Unfortunately, no faecal source tracking method is available to date which is sensitive enough for appropriate spring water monitoring and source allocation. Our purpose was to develop a Duplex Scorpion real-time PCR approach for the specific and sensitive quantification of Bacteroides sp. 16S rDNA fragments from human and cattle origin. By the developed approach, detection of plasmids, carrying the respective biomarker sequence, was possible over a range of more than seven orders of magnitudes down to six copy numbers per PCR assay. Furthermore, the Duplex Scorpion real-time PCR allowed the specific quantification down to 50 targets in plasmid spiked spring water matrices. Results indicate that microbial source tracking appears feasible in spring water habitats by probe-based real-time PCR technologies. However, preliminary testing of the established approach on faecal samples collected from a representative alpine habitat did not allow unambiguous source allocation in all cases. In the future, the available sequence database has thus to be widened to allow reliable source tracking in alpine spring watersheds and even expand this approach to other potential faecal sources.

Animals↗

PubMed2006

Continuous separation of microparticles by size with direct current-dielectrophoresis.

Direct current-dielectrophoresis (DC-DEP), the induced motion of the dielectric particles in a spatially nonuniform DC electric field, is demonstrated to be a highly efficient method to separate the microparticles by size. The locally nonuniform electric field is generated by an insulating block fabricated inside a polydimethylsiloxane microchannel. The particle experiences a negative DEP (accordingly a repulsive force) at the corners of the block, where the local electric-field strength is the strongest. Thus, the particle deviates from the streamline and the degree of deviation is dependent on the DEP force (i.e., the particle size). Combined with the electrokinetic flow, mixed polystyrene particles of a few micrometers difference in diameter can be continuously separated into distinct reservoirs. For separating target particles of a specific size, it is required to simply adjust the voltage outputs of the electrodes. A numerical model based on the Lagrangian tracking method is developed to simulate the particle motion and the results showed a reasonable agreement with the experimental data.

Electrophoresis↗

PubMed2001

Enhancing smoking cessation of low-income smokers in managed care.

BACKGROUND: Although office-based and telephone support services enhance the rate of smoking cessation in managed care systems, it is not clear whether such services are effective for very low-income smokers. We evaluated the comparative effectiveness of usual care (physician-delivered advice and follow-up) and usual care enhanced by 6 computer-assisted telephonic-counseling sessions by office nurses and telephone counselors for smoking cessation in very low-income smokers in Medicaid managed care. METHODS: A randomized clinical trial comparing the 2 approaches was conducted in 3 Michigan community health centers. All clinicians and center staff received standard training in usual care. Selected nurses and telephone counselors received special training in a computer-assisted counseling program focusing on relapse prevention. RESULTS: The majority of the study population (233 adult smokers with telephones) were white (64%) women (70%) with annual incomes of less than $10,000 (79%) and with prescriptions of nicotine replacement therapy (>90%). At 3 months, quit rates (smoke-free status verified by carbon monoxide monitors) were 8.1% in the usual-care group and 21% in the telephonic-counseling group (P=.009) by intention-to-treat analysis. Special tracking methods were successful in maintaining participants in treatment. CONCLUSIONS: Smoking cessation rates are enhanced in a population of very low-income smokers if individualized telephonic-counseling is provided. State and Medicaid managed care plans should consider investing in both office-based nurse and centralized telephonic-counseling services for low-income smokers.

Adult↗

PubMed2004

Practice trends of dental hygiene students completing specialty tracks.

PURPOSE: The purpose of this research was to determine the practice trends of dental hygiene baccalaureate degree recipients who participated in a specialty track. METHODS: A survey was developed, pilot tested, revised, and mailed to a sample of 265 dental hygienists who graduated from the baccalaureate degree dental hygiene program at University of North Carolina (UNC)-Chapel Hill School of Dentistry between 1987 and 1998. Analysis included descriptive statistics, a non-parametric analysis of variance for the ordinal-scaled responses, and a chi-square to compare nominal responses. RESULTS: Survey responses along with telephone interviews yielded a response rate of 68% (n=181). Seventy percent of the respondents had been practicing dental hygiene for six or more years. Ninety-six percent had worked in general private dental practice, 29% in a periodontal dental practice, and 18% in a pediatric dental setting. The top three specialty tracks completed were hospital dentistry (24%), periodontology (20%), and pediatric dentistry (19%). Fifty-six percent of respondents would like to obtain a specialty track position if given the opportunity. Forty-four percent (n=16) of those who experienced the periodontal specialty track have worked in a periodontal setting, and 36% (n=12) of those who participated in the pediatric specialty track have worked in a pediatric office. Eighty-eight percent agreed or strongly agreed that the specialty track was an important part of their dental hygiene education. CONCLUSION: The results imply that the specialty track is a positive learning experience for students and should be continued. Data from this survey has implications to other dental hygiene programs offering or planning to offer specialty tracks.

Chi-Square Distribution↗

PubMedDate not supplied

Fast-tracking of myocardial infarction by paramedics.

OBJECTIVE: To study the effectiveness of a fast-track method of admitting patients with myocardial infarction directly to the coronary care unit (CCU). STUDY DESIGN: Ambulance paramedic staff were trained and provided with a Life Pak XI Monitor/Defibrillator which can obtain a 12-lead electrocardiogram. When a diagnosis of acute myocardial infarction was made by the paramedics, the CCU was informed and the patient was directly transferred to the CCU, bypassing the accident and emergency (A&E) department. The appropriateness of admission to the CCU was assessed against set criteria. The time from call for help to the administration of thrombolytic therapy (thrombolysis time) in patients directly admitted to the CCU was compared with that in another group of patients with definite myocardial infarction who were admitted through the A&E department over the same period of time. RESULTS: Twenty-five patients were fast-tracked to the CCU. Diagnosis of myocardial infarction was confirmed on admission in 14. Thirteen were treated with thrombolysis as there were no contra-indications; of the other 11 patients, seven were diagnosed as angina, one had complete heart block, one had haemodynamically significant atrial fibrillation and two had non-cardiac chest pain. The average time from call for help to thrombolysis in this group was 82 +/- 32 minutes. This was significantly shorter (p < 0.02) than in the patients who were admitted through A&E, in whom the average time from call for help to thrombolysis was 112 +/- 35 minutes. Twenty-one of 25 fast-tracked patients fulfilled the criteria for CCU admission. CONCLUSION: The majority of fast-trackings are appropriate and will result in quicker administration of thrombolysis in hospitals where the facility for thrombolysis does not exist in the A&E department.

Chest Pain↗

PubMed2006

The effects of the Two-Week Rule on NHS colorectal cancer diagnostic services: a systematic literature review.

BACKGROUND: The Two-Week Rule (TWR) was introduced to ensure that all patients with a suspected colorectal cancer (CRC) saw a hospital specialist within 14 days of an urgent GP referral. Guidelines were available to GPs to facilitate the appropriate TWR referral of patients exhibiting high-risk CRC symptoms. METHODS: We aimed to evaluate the TWR and its CRC detection rate on NHS CRC diagnostic services by performing a literature search and critically appraising the peer-reviewed studies. Only 12 studies were eligible for inclusion. Data was collected and overall results were given as weighted averages. RESULTS: The studies identified indicated that only 10.3% of patients referred by the TWR were eventually diagnosed with CRC. When examining the referral origin of all CRC patients diagnosed during the time of the studies, 24% had been referred using the TWR, 24.1% were referred as emergency cases, and 52.4% were referred using alternative routes. No evidence was found to indicate that the TWR had resulted in identifying CRC patients at an earlier, more treatable stage of their disease. CONCLUSION: The TWR referral system needs to be improved to increase the number of CRC patients referred using this fast track method as they present to their GP. The TWR and new NICE Guidelines for the referral of patients with suspected cancer should be independently evaluated.

Colorectal Neoplasms↗

PubMed2005

A novel device for delivering two-site vibrotactile stimuli to the skin.

Current methods for applying two-site vibration stimuli to the skin typically involve the use of two separate vibrotactile stimulators, which can lead to difficulty with positioning of stimuli and in ensuring that stimuli are delivered perfectly in phase at the same amplitude and frequency. This report describes the Two-Point Stimulator (TPS) that was developed in order to deliver two-point stimuli to the skin at variable distances between the sites of stimulation on a trial-by-trial basis. The apparatus attaches to a vibrotactile stimulator, modifying it from the standard single probe tip to two probe tips. Each of the two probe tips can be independently positioned to set the tip-to-tip spacing. Both points of the TPS are driven by the single vibrotactile stimulator and distances between the two sites can be varied on a trial-by-trial basis. To test the device, a modified Bekesy tracking method was developed and used for two-point limen testing under stimulus conditions of varying amplitude and frequency. Data collected were consistent with previously published reports, suggesting that one possible use of the device would be to provide a means for improved measures of spatio-tactile acuity.

Adult↗

PubMed2003

Visualizing single molecules inside living cells using total internal reflection fluorescence microscopy.

Over the past 10 years, advances in laser and detector technologies have enabled single fluorophores to be visualized in aqueous solution. Here, we describe methods based on total internal reflection fluorescence microscopy (TIRFM) that we have developed to study the behavior of individual protein molecules within living mammalian cells. We have used cultured myoblasts that were transiently transfected with DNA plasmids encoding a target protein fused to green fluorescent protein (GFP). Expression levels were quantified from confocal images of control dilutions of GFP and cells with 1-100 nM GFP were then examined using TIRFM. An evanescent field was produced by a totally internally reflected, argon ion laser beam that illuminated a shallow region (50-100 nm deep) at the glass-water interface. Individual GFP-tagged proteins that entered the evanescent field appeared as individual, diffraction-limited spots of light, which were clearly resolved from background fluorescence. Molecules that bound to the basal cell membrane remained fixed in position for many seconds, whereas those diffusing freely in the cytoplasm disappeared within a few milliseconds. We developed automated detection and tracking methods to recognize and characterize the behavior of single molecules in recorded video sequences. This enabled us to measure the kinetics of photobleaching and lateral diffusion of membrane-bound molecules.

Animals↗

PubMed2005

[Modified molecular beacon-based dual real-time PCR for detection of SARS virus and its application].

OBJECTIVE: To develop the modified molecular beacon-based dual fluorescent PCR assays for detection of SARS virus. The assay was applied to the early clinic diagnosis & animal tracking. METHODS: On the basis of the obtained core sequence of open reading frame 1b of the coronavirus polymerase gene sequences, which was published in GenBank, using modified molecular beacon probe, artifical virus techinique and two different fragments amplification with different fluoresce, one set of primers and probe were designed. Then fluorescent PCR assays for specific and sensitive detection of the SARS virus was established, while the ELISA & the traditional method were used as control. 368 clinical specimens such as the throat swab, serum, feces, and urine from different cases, 52 cell cultures and 50 animal specimens were detected by the molecular beacon-based PCR. RESULTS: The sensitivity of real -time PCR was 10 - 100 copies/ml, there was no cross reaction to other respiratory viruses such as influenza virus etc. Of 368 specimens, 20 were positive by using molecular beacon-based fluorescence PCR. The positive rate of SARS case (10/47) were 21.27%, the positive rate of the throat swab of SARS cases (10/23) were 43.87% . Among 52 SARS cell cultures, 29 were positive. The positive rate of SARS cell cultures was 55.77% . Of 50 animal specimens, 23 were positive. The positive rate was 46%. Furthermore, SARS virus RNA was detected in feces and in serum during the acute phase. CONCLUSION: The molecular beacon-based PCR is sensitive and specific, it could be applied to the early diagnosis and animal tracking. This molecular beacon-based PCR kit is useful for the different units.

Animals↗

PubMed2003

Endogenous assays of DNA methyltransferases: Evidence for differential activities of DNMT1, DNMT2, and DNMT3 in mammalian cells in vivo.

While CpG methylation can be readily analyzed at the DNA sequence level in wild-type and mutant cells, the actual DNA (cytosine-5) methyltransferases (DNMTs) responsible for in vivo methylation on genomic DNA are less tractable. We used an antibody-based method to identify specific endogenous DNMTs (DNMT1, DNMT1b, DNMT2, DNMT3a, and DNMT3b) that stably and selectively bind to genomic DNA containing 5-aza-2'-deoxycytidine (aza-dC) in vivo. Selective binding to aza-dC-containing DNA suggests that the engaged DNMT is catalytically active in the cell. DNMT1b is a splice variant of the predominant maintenance activity DNMT1, while DNMT2 is a well-conserved protein with homologs in plants, yeast, Drosophila, humans, and mice. Despite the presence of motifs essential for transmethylation activity, catalytic activity of DNMT2 has never been reported. The data here suggest that DNMT2 is active in vivo when the endogenous genome is the target, both in human and mouse cell lines. We quantified relative global genomic activity of DNMT1, -2, -3a, and -3b in a mouse teratocarcinoma cell line. DNMT1 and -3b displayed the greatest in vivo binding avidity for aza-dC-containing genomic DNA in these cells. This study demonstrates that individual DNMTs can be tracked and that their binding to genomic DNA can be quantified in mammalian cells in vivo. The different DNMTs display a wide spectrum of genomic DNA-directed activity. The use of an antibody-based tracking method will allow specific DNMTs and their DNA targets to be recovered and analyzed in a physiological setting in chromatin.

Animals↗

PubMed1999

Quantitative MR measures of three-dimensional patellar kinematics as a research and diagnostic tool.

PURPOSE: A three-dimensional (3D) study of normal patellar-femoral-tibial (knee) joint kinematics was performed using Cine Phase Contrast Magnetic resonance imaging (Cine-PC MRI) to determine the utility of this technique as a diagnostic tool in defining alterations in patellar tracking. METHODS: Cine-PC MRI was originally developed to measure heart motion and blood flow and has now been adapted to the study of the musculoskeletal system. Thus, for the first time knee joint kinematics can be studied three-dimensionally, noninvasively, and in vivo during dynamic volitional leg extensions under load. Cine-PC MRI provides one anatomic and three orthogonal velocity images (vx, vy, and vz) for each time frame within the motion cycle. Bone displacements are calculated using integration and are then converted into both 3D orientation angles and 2D clinical angles. RESULTS: The 3D patellar tilt and 2D clinical patellar tilt angle were nearly identical, even though these two angles have distinct mathematical definitions. The precision of the 2D clinical patellar tilt angle (N = 3) was approximately 2.4 degrees. CONCLUSIONS: Since the overall subject (N = 18) variability for clinical patellar tilt angle and medial/lateral patellar displacement was low (SD = 2.9 degrees and 3.3 mm, respectively), Cine-PC MRI could prove to be a valuable tool in studying subtle changes in patellar tracking.

Adult↗