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PubMed1997

Immunisation coverage in Christchurch in a birth cohort. Christchurch Immunisation Coordination Committee.

AIM: To ascertain the immunisation status of a birth cohort of infants at 8 months of age. METHODS: Data on all children born in Christchurch in June, July and August 1995 were matched with immunisation benefit claim information for the 6-week, 3-month and 5-month immunisation events. Those not listed as receiving all three immunisations by the age of 8 months were traced to ascertain their immunisation status. RESULTS: Immunisation status was established for 933 (93.1%) of the cohort of 1002 infants. Of these, 95% had received all three immunisations that were scheduled up to 5 months of age. This represents a coverage of at least 88.2% of the entire cohort. It was probable that many of those not traced would also have been fully immunised. Using a conservative estimate of coverage among this group, we calculated that 93% of the entire cohort had been fully immunised by the age of 8 months. CONCLUSION: There was a high immunisation coverage rate in Christchurch. This is in contrast to a commonly held view that children in New Zealand have a poor immunisation record. There was no evidence of a significant anti-immunisation stance among Christchurch parents. Immunisation data relevant to specific, defined populations can identify individual children and groups of children who may require assistance beyond general practitioner recall to achieve appropriate immunisation. The tracking process also allowed for immunisation reminders to be personally delivered and included some facilitation for achieving further immunisation. We suggest that a pilot programme, using a centralised register based on birth data, feeding into existing immunisation delivery and recall systems, and using tracking methods similar to those used in our study, should be the next step in addressing immunisation coverage surveillance and immunisation coordination in Christchurch.

Birth Certificates↗

PubMed2001

Prey-capture behavior in gymnotid electric fish: motion analysis and effects of water conductivity.

Animals can actively influence the content and quality of sensory information they acquire from the environment through the positioning of peripheral sensory surfaces. This study investigated receptor surface positioning during prey-capture behavior in weakly electric gymnotiform fish of the genus Apteronotus. Infrared video techniques and three-dimensional model-based tracking methods were used to provide quantitative information on body position and conformation as black ghost (A. albifrons) and brown ghost (A. leptorhynchus) knifefish hunted for prey (Daphnia magna) in the dark. We found that detection distance depends on the electrical conductivity of the surrounding water. Best performance was observed at low water conductivity (2.8 cm mean detection distance and 2 % miss rate at 35 microS cm(-)(1), A. albifrons) and poorest performance at high conductivity (1.5 cm mean detection distance and 11 % miss rate at 600 microS cm(-)(1), A. albifrons). The observed conductivity-dependence implies that nonvisual prey detection in Apteronotus is likely to be dominated by the electrosense over the range of water conductivities experienced by the animal in its natural environment. This result provides the first evidence for the involvement of electrosensory cues in the prey-capture behavior of gymnotids, but it leaves open the possibility that both the high-frequency (tuberous) and low-frequency (ampullary) electroreceptors may contribute. We describe an electrosensory orienting response to prey, whereby the fish rolls its body following detection to bring the prey above the dorsum. This orienting response and the spatial distribution of prey at the time of detection highlight the importance of the dorsal surface of the trunk for electrosensory signal acquisition. Finally, quantitative analysis of fish motion demonstrates that Apteronotus can adapt its trajectory to account for post-detection motion of the prey, suggesting that it uses a closed-loop adaptive tracking strategy, rather than an open-loop ballistic strike strategy, to intercept the prey.

Animals↗

PubMed2006

Automated detection of videotaped neonatal seizures of epileptic origin.

PURPOSE: This study aimed at the development of a seizure-detection system by training neural networks with quantitative motion information extracted from short video segments of neonatal seizures of the myoclonic and focal clonic types and random infant movements. METHODS: The motion of the infants' body parts was quantified by temporal motion-strength signals extracted from video segments by motion-segmentation methods based on optical flow computation. The area of each frame occupied by the infants' moving body parts was segmented by clustering the motion parameters obtained by fitting an affine model to the pixel velocities. The motion of the infants' body parts also was quantified by temporal motion-trajectory signals extracted from video recordings by robust motion trackers based on block-motion models. These motion trackers were developed to adjust autonomously to illumination and contrast changes that may occur during the video-frame sequence. Video segments were represented by quantitative features obtained by analyzing motion-strength and motion-trajectory signals in both the time and frequency domains. Seizure recognition was performed by conventional feed-forward neural networks, quantum neural networks, and cosine radial basis function neural networks, which were trained to detect neonatal seizures of the myoclonic and focal clonic types and to distinguish them from random infant movements. RESULTS: The computational tools and procedures developed for automated seizure detection were evaluated on a set of 240 video segments of 54 patients exhibiting myoclonic seizures (80 segments), focal clonic seizures (80 segments), and random infant movements (80 segments). Regardless of the decision scheme used for interpreting the responses of the trained neural networks, all the neural network models exhibited sensitivity and specificity>90%. For one of the decision schemes proposed for interpreting the responses of the trained neural networks, the majority of the trained neural-network models exhibited sensitivity>90% and specificity>95%. In particular, cosine radial basis function neural networks achieved the performance targets of this phase of the project (i.e., sensitivity>95% and specificity>95%). CONCLUSIONS: The best among the motion segmentation and tracking methods developed in this study produced quantitative features that constitute a reliable basis for detecting neonatal seizures. The performance targets of this phase of the project were achieved by combining the quantitative features obtained by analyzing motion-strength signals with those produced by analyzing motion-trajectory signals. The computational procedures and tools developed in this study to perform off-line analysis of short video segments will be used in the next phase of this project, which involves the integration of these procedures and tools into a system that can process and analyze long video recordings of infants monitored for seizures in real time.

Automation↗

PubMed1998

Probing the morphological developmental path of plant embryos by image tracking

An image analysis and pattern recognition system was applied to track the morphological changes of individual plant somatic embryos during the course of their development into mature embryos. A Fourier descriptor was used to transform the morphological information into quantitative features (Fourier features), which are amenable to mathematical and statistical analysis. At a given time point, the status of each developing embryo is represented by a point in the multidimension feature space spanned by these Fourier features. Connecting each point representing the individual embryos over time gives a trajectory which depicts the embryos' developmental "path" or history. Large variations in embryo development were observed, which is consistent with the population heterogeneity seen in batch embryo cultures. The rate at which each embryo progresses in the feature space was measured by a developmental vector. For embryos in a given class or developmental stage, the magnitude of the developmental vector exhibited a wide distribution. The results revealed that embryos with a higher developmental rate during the early stage of development had a higher chance of reaching the mature stage in a relatively short time. This single embryo tracking method is potentially a valuable tool in developing a correlation between the embryo's morphological features during the early stage of development and its eventual developmental fate. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗

PubMed2000

Solid-phase combinatorial synthesis using MicroKan reactors, Rf tagging, and directed sorting.

A modular system for high-output solid-phase combinatorial synthesis has been designed and developed. The system employs three technological innovations to achieve its high efficiency and reliability: (1) application of microreactors as the reaction units in solid-phase synthesis; (2) use of radiofrequency tagging as the non-chemical tracking method; and (3) development of the directed sorting technology for split & pool synthesis. The system has been successfully applied in the synthesis of compound libraries of several hundred to several thousand compounds in multi-milligrams per compound quantity by many organizations.

Chemistry, Organic↗

PubMed1999

Magnetic resonance-guided vascular catheterization: feasibility using a passive tracking technique at 0.2 Telsa in a pig model.

The objective of this study was to demonstrate in an animal model the feasibility of a passive tracking technique for catheter visualization of magnetic resonance (MR)-guided endovascular procedures. All experiments were performed in a 0.2 Tesla open MR system. Susceptibility-based catheters and guide wires were introduced into the aorta and were advanced selectively into the splenic and renal arteries under MR guidance. Based on a previously acquired contrast-enhanced magnetic resonance angiography (MRA) data set, the catheter positioning was performed by using a single-slice true fast imaging with steady state precession (FISP) sequence with a frame rate of 1.3 seconds. Contrast-enhanced MRA was performed in all animals. All catheters were advanced without complications into the aorta and were introduced into the proximal parts of the right renal and splenic arteries under MR guidance. Catheter manipulations were more difficult in the distal parts of these vessels due to the more complex anatomy. Passive catheter tracking is a valuable and technically robust alternative to active tracking methods, because it does not require additional hardware and, thus, can be implemented and used easily with any open MR imaging system. J. Magn. Reson. Imaging 1999;10:841-844.

Animals↗

PubMed1990

Motion of individual human spermatozoa, both normal and lacking the outer dynein arms, during a continuous temperature rise.

The effect of increasing temperature from 22-25 degrees C to 37 degrees C on various motion characteristics of individual normal human spermatozoa and spermatozoa lacking the outer dynein arms (LODA) was studied by using a new automatic microscopic tracking method. It was found that: 1) The curvilinear velocity (Vc, measured between 1-3 sec) of both normal and LODA spermatozoa, fluctuated more or less intensely between spermatozoa; this fluctuation was not thermodependent. 2) The average Vc in the two groups of spermatozoa increased with the rise in temperature at a similar rate (1 micron/sec/degrees C), but LODA spermatozoa had an initial Vc lower than that of normal spermatozoa (12.5 +/- 5.3 microns/sec and 34.2 +/- 8.2 microns/sec, respectively). 3) The profile of the Vc increase associated with the temperature rise was different for the two groups of spermatozoa: for LODA spermatozoa it was linear between 25-37 degrees C, whereas for normal spermatozoa a plateau was reached at about 31 degrees C. 4) Various patterns of trajectory were found for both normal and LODA spermatozoa; these patterns were unrelated to temperature. However, LODA spermatozoa had more linear trajectories than normal spermatozoa. 5) Plots derived from reaction rate theory showed that the activation enthalpy, delta H was a function of the increase of Vc for both normal and LODA spermatozoa, but that delta H was higher for LODA spermatozoa.

Adenosine Triphosphatases↗

PubMed2005

Optic radiation changes after optic neuritis detected by tractography-based group mapping.

Postmortem data suggest that trans-synaptic degeneration occurs in the lateral geniculate nucleus after optic nerve injury. This study investigated in vivo the optic radiations in patients affected by optic neuritis using fast marching tractography (FMT), a diffusion magnetic resonance imaging (MRI) fiber tracking method, and group mapping techniques, which allow statistical comparisons between subjects. Seven patients, 1 year after isolated unilateral optic neuritis, and ten age and gender-matched controls underwent whole-brain diffusion tensor MR imaging. The FMT algorithm was used to generate voxel-scale connectivity (VSC) maps in the optic radiations in each subject in native space. Group maps of the left and right optic radiations were created in the patient and control group in a standardized reference frame using statistical parametric mapping (SPM99). The reconstructed optic radiations in the patient group were localized more laterally in the posterior part of the tracts and more inferiorly than in the control group. Patients showed reduced VSC values in both tracts compared with controls. These findings suggest that the group mapping techniques might be used to assess changes in the optic radiations in patients after an episode of optic neuritis. The changes we have observed may be secondary to the optic nerve damage.

Adult↗

PubMed2003

A framework for a streamline-based probabilistic index of connectivity (PICo) using a structural interpretation of MRI diffusion measurements.

PURPOSE: To establish a general methodology for quantifying streamline-based diffusion fiber tracking methods in terms of probability of connection between points and/or regions. MATERIALS AND METHODS: The commonly used streamline approach is adapted to exploit the uncertainty in the orientation of the principal direction of diffusion defined for each image voxel. Running the streamline process repeatedly using Monte Carlo methods to exploit this inherent uncertainty generates maps of connection probability. Uncertainty is defined by interpreting the shape of the diffusion orientation profile provided by the diffusion tensor in terms of the underlying microstructure. RESULTS: Two candidates for describing the uncertainty in the diffusion tensor are proposed and maps of probability of connection to chosen start points or regions are generated in a number of major tracts. CONCLUSION: The methods presented provide a generic framework for utilizing streamline methods to generate probabilistic maps of connectivity.

Anisotropy↗

PubMed2002

Neural cells derived from adult bone marrow and umbilical cord blood.

Under experimental conditions, tissue-specific stem cells have been shown to give rise to cell lineages not normally found in the organ or tissue of residence. Neural stem cells from fetal brain have been shown to give rise to blood cell lines and conversely, bone marrow stromal cells have been reported to generate skeletal and cardiac muscle, oval hepatocytes, as well as glia and neuron-like cells. This article reviews studies in which cells from postnatal bone marrow or umbilical cord blood were induced to proliferate and differentiate into glia and neurons, cellular lineages that are not their normal destiny. The review encompasses in vitro and in vivo studies with focus on experimental variables, such as the source and characterization of cells, cell-tracking methods, and markers of neural differentiation. The existence of stem/progenitor cells with previously unappreciated proliferation and differentiation potential in postnatal bone marrow and in umbilical cord blood opens up the possibility of using stem cells found in these tissues to treat degenerative, post-traumatic and hereditary diseases of the central nervous system.

Adult↗

PubMed1990

Velocity imaging of slow coherent flows using stimulated echoes.

We measure the velocity distribution of slow fluid flow in model systems using stimulated echoes and velocity phase encoding. We show velocity images of slow coherent flow with velocities of the order of 0.1 mm/s which is slower than can be obtained by the bolus-tracking method. The eddy current errors were compensated by phase correction.

Humans↗

PubMedDate not supplied

Epidemiology of low total plasma cholesterol concentration among young adults: the CARDIA study. Coronary Artery Risk Development in Young Adults.

BACKGROUND: Data on stability of plasma total cholesterol levels and its determinants among young adults are lacking. Knowledge of factors associated with low levels of plasma total cholesterol during young adulthood may help clarify the nature of associations between hypocholesterolemia and health or illness. METHODS: Tracking of plasma total cholesterol was investigated using data from the baseline (1985-1986), Year 5 (1990-1991), and Year 7 (1992-1993) examinations of the Coronary Artery Risk Development in Young Adults Study. Lifestyle (including dietary), physiological, medical, and psychological correlates of plasma total cholesterol were examined cross-sectionally at baseline using ANCOVA and multivariate logistic regression. The attributes of participants with persistently low plasma total cholesterol level after 7 years (i.e., remaining below the 10th percentile of sex- and race-specific distributions) were also examined. RESULTS: The cohort in this analysis comprised 720 black men, 922 white men, 899 black women, and 944 white women who were between the ages of 18 and 30 years at baseline. Between 44 and 52% of those with plasma total cholesterol levels below the 10th percentile remained below the same percentile 7 years later. Among black men, a difference of 1 SD in age [3.7 years; odds ratio (OR) = 0.69; 95% CI = 0.52-0.91] and a difference of 1 SD in systolic blood pressure (10.5 mm Hg; OR = 0.73; 95% CI = 0.54-0.97) were independently associated with lower odds, respectively, of being in the lowest 10th percentile of the plasma total cholesterol distribution. Also among black men, current smoking and more calories from carbohydrates were associated with nonsignificantly higher odds of low total cholesterol level. Among white men, a 1 SD older age (3.4 years; OR = 0.78; 95% CI = 0.61-1.00) and a 1 SD higher physical fitness (118 sec; OR = 1.41; 95% CI = 1.09-1.82) predicted lower and higher odds, respectively, of low plasma total cholesterol. Among black women, a 1 SD difference in albumin (0.3 g/dL; OR = 0.80; 95% CI = 0.63-1.03) was related to lower odds of low plasma total cholesterol. Among white women, the factors independently associated with low plasma total cholesterol were body mass index (OR for a difference in 4.0 kg/m2 = 0.73; 95% CI = 0.54-1.00) and gamma-glutamyl transferase (OR for an increase in 9.6 IU/L = 0.41; 95% CI = 0.18-0.93). The independent predictive factors of stably low total cholesterol levels were age and uric acid among black men (both inversely related) and age, Framingham Type A Behavior (inversely), and calories from carbohydrates (positively related) among white men. CONCLUSION: Young adults with low plasma total cholesterol level have characteristics generally associated with good cardiovascular health. However, adverse attributes such as current cigarette smoking (notably among black men) may confound future associations between low total cholesterol and disease.

Adolescent↗

PubMed1988

Disorder in reciprocal innervation upon initiation of voluntary movement in patients with Parkinson's disease.

Reciprocal innervation of the soleus motoneurones upon initiation of voluntary ankle dorsiflexion was investigated in eight patients with Parkinson's disease. H-reflex and visually guided step tracking methods were used for testing motoneurone excitability and for controlling the timing of movement initiation, respectively. While reciprocal inhibition appeared almost simultaneously with the agonist electromyographic (EMG) onset in normal subjects (Kagamihara and Tanaka 1985), facilitation appeared in the majority of patients under the same onset condition. It increased slowly, reaching a maximum at about 100 ms after the EMG onset. It then subsided slowly at around 200-300 ms, and was replaced thereafter by an inhibitory effect. No coactivation of the soleus muscle was detected electromyographically. The facilitation between the EMG onset and the onset of mechanical contraction was attributed to the direct effect of the descending command from the brain, suggesting a certain disorder in controlling the system for reciprocal innervation.

Adult↗

PubMed1987

Rheumatic complaints in Tokelau. I. Migrants resident in New Zealand. The Tokelau Island migrant study.

The three Tokelau atolls are 8 degrees south of the equator. In 1966 the islands were involved in a severe hurricane which drew attention to overcrowding and led to resettlement of more than half the population in New Zealand. One thousand three hundred and eighty one migrants over 15 years old were examined in New Zealand in 1980 and 1981 for rheumatic complaints as part of a continuing assessment. Clinical criteria for osteoarthritis (COA), including crepitus in any joint and in the knee, showed an increase in prevalence with age and weight in both sexes. Partial correlation coefficient analysis showed an association of the number of affected joints or the severity of knee COA (COAK) with both age and weight. Stepwise regression showed that age was the best predictor of both COA and COAK scores. Weight had predictive value only for COAK and only in women. Using the tracking method, previous high and/or increasing weight was related to COAK observed at this assessment. Heberden nodes increased with age and were more prevalent in women but were not associated with weight. Low back, dorsal and neck pain showed no association with age or sex. Low back pain was associated with weight. Joint pain following injury occurred in 15.4% of men. Gout, more common in men, was the only frequent inflammatory arthritis found. Two definite cases of rheumatoid arthritis (RA) were identified and four had criteria 1 and 2 for the New York criteria.

Adolescent↗

PubMed1995

Dynamic functional and structural analysis of living cells: new tools for vital staining of nuclear DNA and for characterisation of cell motion.

Increasing interest has been paid to applications of fluorescence measurements to analyze physiological mechanisms in living cells. However, few studies have taken advantage of DNA quantification by fluorometry for dynamic assessment of chromatin organization as well as cell motion during the cell cycle. This approach involves both optimal conditions for DNA staining and cell tracking methods. In this context, this report describes a stoichiometric method for nuclear DNA specific staining, using the bisbenzimidazole dye Hoechst 33342 associated with verapamil, a calcium membrane channel blocker. This method makes it possible to correlate variations of nuclear DNA content with cell motion in cells that are maintained alive. Motion measurement is the second goal of this paper and it explains the snake-spline method, and the associated cell following method.

Animals↗

PubMed1985

Extracellular matrix (ECM) modulates the EGF-induced migration of liver epithelial cells in serum-free, hormone-supplemented medium.

The influence of the extracellular matrix (ECM) glycoproteins collagen IV, laminin (LN), and fibronectin (FN) on the in vitro migration of epithelial cells was studied using the ECM migration track method (4) with preparations immunostained for LN and FN. The locomotion of rat liver epithelial cells stimulated to migrate in serum-free medium by epidermal growth factor (EGF) in the presence of insulin is inhibited by substratum-bound FN. The inhibition is concentration-dependent up to 0.7 microgram of the protein per cm2. Neither LN nor collagen IV decreased the number of migrating cells, indicating that the inhibition is a specific effect of fibronectin. The data also indicate that the FN-mediated inhibition of migration is an additional and not alternative mechanism to the well-established contact inhibition of locomotion (1) which also occurs in liver epithelial cell cultures. The system is being used for a further analysis of the factors that influence migration of normal and neoplastic epithelial cells and the biochemical mechanisms underlying the migration reaction.

Animals↗

PubMed2002

Two phases of intracortical inhibition revealed by transcranial magnetic threshold tracking.

Intracortical inhibition was investigated in normal human volunteers by paired-pulse transcranial magnetic stimulation, using a new, computer-assisted threshold-tracking method. Motor threshold was defined as the stimulus amplitude required to evoke a motor evoked potential of 0.2 mV (peak-to-peak) in abductor pollicis brevis, and inhibition was measured as the percentage increase in threshold, when the test stimulus was preceded by a subthreshold conditioning stimulus. This method was used to investigate the dependence of intracortical inhibition on conditioning stimulus parameters and on voluntary activity. Interstimulus interval (ISI) was first stepped from 1 to 4.5 ms, as inhibition was measured using conditioning stimuli of fixed amplitude (50-90% resting motor threshold). Maximal inhibition was produced at ISIs of 1 and 2.5 ms. The effect of conditioning stimulus intensity was then assessed at these ISIs. Inhibition occurred at significantly lower conditioning stimulus intensities with ISI=1 ms than with ISI=2.5 ms. Voluntary activity reduced inhibition at both ISIs, but had a much greater effect on inhibition at ISI=2.5 ms. Inhibition during voluntary activity was also examined for single motor units in first dorsal interosseous by generating poststimulus time histograms. Inhibition, indicated by a reduction in the later peaks of increased firing, was observed with ISI=1 ms, but not with ISI=2.5 ms. We conclude that there are two distinct phases of inhibition, occurring at ISI=1 ms and ISI=2.5 ms, differing both in thresholds and susceptibility to voluntary activity.

Adult↗

PubMed2003

Assessment of brain perfusion with MRI: methodology and application to acute stroke.

We review the methodology of brain perfusion measurements with MRI and their application to acute stroke, with particular emphasis on the work awarded by the 6th Lucien Appel Prize for Neuroradiology. The application of the indicator dilution theory to the dynamic susceptibility-weighted bolus-tracking method is explained, as is the approach to obtaining quantitative measurements of cerebral blood flow (CBF) and volume (CBV). Our contribution to methodological developments, such as CBV measurement with the frequency-shifted burst sequence, development of the PRESTO sequence, comparison of different deconvolution methods and of spin- and gradient-echo sequences, and the validation of MRI measurements against positron emission tomography is summarised. The pathophysiology of brain ischaemia and the role of neuroimaging in the setting of acute stroke are reviewed, with an introduction to the concepts of ischaemic penumbra and diffusion/perfusion mismatch. Our work on the determination of absolute CBF and CBV thresholds for predicting the area of infarct growth, identification of the best perfusion parameters (relative or absolute) for predicting the area of infarct growth and the role of MR angiography is also summarised. We conclude that MRI is a very powerful way to assess brain perfusion and that its use might help in selecting patients who will benefit most from treatment such as thrombolysis.

Acute Disease↗