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PubMed1991

Use of the Trajectory Model of nursing in multiple sclerosis.

Multiple sclerosis (MS) is a chronic, demyelinating disorder that is unpredictable in its overall course, in the type of symptoms that will predominate, and in its eventual outcome. It has been used as a model in research, education, and practice to examine the course of chronic illness, patient and family responses, coping and adjustment to chronic illness, and specific concepts and variables of interest to researchers. MS is used in this paper to evaluate for nursing practice the utility of the Corbin and Strauss trajectory model of nursing. The assumptions and major concepts of the trajectory framework are discussed, use of the model in multiple sclerosis is demonstrated, and the strengths and limitations of the framework as a nursing model are identified.

Chronic Disease↗
PubMed1991

Career choice and professional trajectory of Fifth Pathway students.

We have studied the professional trajectory of 177 participants of the Fifth Pathway Program of the University of Puerto Rico School of Medicine between July 1973 and June 1987. Eighty six per cent of the students were Puerto Rican. Sixty seven per cent had studied in the Universidad Autónoma de Guadalajara. Ninety seven per cen of the respondents specialized and 39 per cent subspecialized; sixty nine per cent selected primary care specialties. Eighty three per cent of the fifth pathway participants are licensed to practice medicine in Puerto Rico and 37% are licensed to practice in one or more of 21 states of the Nation. Twenty one per cent held academic positions and 11.4 per cent were department chairpersons or chiefs of sections. The professional trajectory of Fifth Pathway participants is similar to that of medical graduates of the University of Puerto Rico School of Medicine.

Career Choice↗
PubMed1990

Trajectory reconstructions. I: Trace evidence in flight.

This paper reviews the use of trace evidence recovered from spent bullets in helping to establish trajectories. The use of information derived from such trace evidence combined with that from geometrical techniques of trajectory reconstruction and other data is discussed. Five cases are reviewed in which the analysis of trace evidential materials adhering to bullets was used to help reconstruct the event.

Adult↗
PubMed1989

Trajectory analysis and bluetongue virus serotype 2 in Florida 1982.

Examination of Northern Hemisphere synoptic charts and computation of backward trajectories indicated that Culicoides infected with bluetongue virus serotype 2 could have been carried on the wind and brought the virus to Florida on the afternoon of August 19, 1982 after leaving northern Cuba the previous evening. Flight would have occurred at a height of 1-1.5 km at temperatures of 15-17 degrees C. The distance of 500 km from northern Cuba to Ona would have been covered in 20 h at an average speed of 25 km h-1. Computation of trajectories indicated that a second electropherotype, Ona B, was unlikely to have been introduced by infected Culicoides.

Animals↗
PubMed1987

Application of the three-channel lissajous trajectory of auditory brainstem-evoked potentials to the question of generators.

In studies of generators of auditory brainstem-evoked potentials (ABEP), depth recordings and clinical correlates may not reflect all the activity involved. Although the 'inverse problem' is mathematically ill-posed, a synthesis of physico-anatomical data with a three-channel Lissajous trajectory (3CLT) may indicate the actual number and identity of generators. A 3CLT of ABEP in three-dimensional voltage space, is isomorphic with the vector tip representing the momentary centrally located dipole in a uniform, spherical volume conductor. This isomorphism enables approximations of ABEP dipole equivalents to be made. 3CLT summarizes the surface activity in a single plot. It accentuates correlations within the orthogonal records, such as planarity of segments, allowing segmentation of the analysis epoch into components. These properties of 3CLT simplify the analysis of parametric effects on the surface distribution of ABEP components. The results of applying this technique indicate the experimental conditions under which the assumptions for the approximation of generators are closest to being fulfilled. Of all the points along the trajectory, apices (points with maximum absolute amplitude and curvature) have the most unique generators. The 3CLT to low-intensity and high-rate clicks, indicate more unique generators than the customarily used high-intensity slow-rate clicks, in which considerable temporal overlap of generator activity exists.

Brain Stem↗
PubMed1985

Growth cone morphology and trajectory in the lumbosacral region of the chick embryo.

We quantitatively analyzed several features of orthogradely labeled peripheral growth cones in the lumbosacral region of the chick embryo. We compared motoneuron growth cones in regions where they appear to express specific directional preferences (the plexus region and regions where muscle nerves diverge from main nerve trunks), which we operationally defined as "decision regions," to motoneuron growth cones in other pathway regions (the spinal nerve, nerve trunk, and muscle nerve pathways) which we termed, for contrast, "non-decision region." We found that motoneuron growth cones are larger, more lamellepodial, and have more complex trajectories in decision regions. Sensory growth cone populations, which are thought to be dependent upon motoneurons for outgrowth (Landmesser, L., and M. Honig (1982) Soc. Neurosci. Abstr. 8: 929), do not enlarge or become more lamellepodial in motoneuron decision regions, suggesting that this local environment does not affect all species of growth cones equally and that the alterations in motoneuron growth cones in these regions may be relevant to their specific guidance. In addition, the resemblance between the sensory population and other closely fasciculating growth cones lends support to the suggestion that sensory neurons utilize motoneuron neurites as a substratum. We suggest that the convoluted trajectories, enlarged size, and more lamellepodial morphology of motoneuron growth cones in decision regions is either related directly to the presence of specific cues that guide motoneurons or to some aspect of this environment that allows them to respond to specific cues.

Animals↗
PubMed1979

[Electrotropic acetylcholine action on the mammalian auricle by means of the "phase plane" trajectories of the action potential].

A single sucrose gap techniques has been used to study action potentials and phase plane trajectories of them in atrial trabeculae of the rabbit. Using polynomial representations of current-voltage relationships a model of membrane action potential of atrial myocardial fibres is described and allows an interpretation of recording data from the phase plane trajectories. Our findings show: 1. Increasing extracellular calcium concentration increases a potassium conductivity of the atrial membrane. 2. An anomalous rectification concerning repolarizing currents in atrial fibres decreases with increasing extracellular calcium. 3. Acetylcholine (3.10(-4) g.cm-3) abolishes the anomalous rectification. These results are discussed in relation to previous electrophysiological studies of negative electrotropic effects of acetylcholine in cardiac muscle.

Acetylcholine↗
PubMed1984

Posture control and trajectory formation during arm movement.

One hypothesis for the generation of spatially oriented arm movements by the central nervous system is that a desired joint position is determined by the ratio of the tensions of agonist and antagonist muscles. According to this hypothesis, the transition between equilibrium states should be solely a function of the contraction time of the motor units and the mechanical properties of the arm. We tested this hypothesis in intact and deafferented rhesus monkeys by holding the forearm and measuring the accelerative transient after release of the forearm and by directly measuring the time course of the increase in torque during the movement. Both methods indicated an average time of 400 msec for attaining peak torque in a movement with a duration of 700 msec. In addition, by displacing the arm from its normal trajectory during the movement, we observed that the arm returned neither to the initial nor to the final equilibrium positions, but to points intermediate between them. We conclude that the processes underlying trajectory formation must be more complex than a simple switch between one equilibrium position and another.

Afferent Pathways↗
PubMed1996

Trajectories of poverty and children's mental health.

Using data from three waves of the Children of the National Longitudinal Surveys of Youth data set (1986, 1988, 1990), we examine the dynamic relationship between children's family histories of poverty and their developmental trajectories of mental health. Children who were poor in 1986 or who had prior histories of poverty had higher levels of depression and antisocial behavior in that year. Furthermore, subsequent poverty histories were also related to children's mental health trajectories. The number of years that children were poor between 1986 and 1990 correlates significantly with changes in children's antisocial behavior during those years. Finally, rates of increase in antisocial behavior were substantially higher for children with histories of persistent poverty during those years than for transiently poor or nonpoor children. These results demonstrate the accelerating behavioral disadvantages faced by persistently poor children.

Adolescent↗
PubMedDate not supplied

[Molecular dynamics of oligopeptides. 1. The use of long trajectory and high temperature data for determination of statistical weight of conformational substates].

The method of molecular dynamics investigations of the particularities of macromolecule physical-chemical properties is discussed. The results, obtained from the calculations of modified dipeptides in different regimes (different temperatures, length of trajectories and ways of thermostat simulation) are compared. The optimal conditions for this peptides calculations are determined: collisional dynamics regime, trajectories not less than 5000 ps, temperature about 1000 K. In this case the figurative point is able to scan the molecule configuration space and the statistically reliable results could be obtained.

Dipeptides↗
PubMed1997

Paralysis and long bone growth in the chick: growth shape trajectories of the pelvic limb.

Growth of chick embryonic femora, tibiotarsi and first phalanges of digit three were measured at one day intervals from day 6 through 16 of incubation. Normal controls were compared to embryos paralyzed at 5 days of incubation. Over the 10 day study period, length of the paralyzed femora, length and width of the paralyzed tibiotarsi and differences in length of the phalanges were observed. Growth in length of phalanx one of digit three was most affected by paralysis over this period. Changes in shape of these bones also occurred during growth. Normal long bones undergo changes in shape as differential growth in length and width occurs. Such changes in shape can be considered as the bone's normal growth "trajectory". Paralyzed bones displayed a different growth trajectory than normal bones. As expected, the long bones of paralyzed embryos were shorter than age-matched controls. Contrary to expectations, however, paralyzed long bones were relatively more stout than age-matched controls.

Animals↗
PubMed1997

A simple trajectory guidance device that assists freehand and interactive image guided biopsy of small deep intracranial targets.

Frameless image guided stereotactic systems are rapidly becoming incorporated into routine neurosurgical practice. In our unit, the Elekta Viewing Wand has been applied to a comprehensive range of neurosurgical procedures, including pituitary, posterior fossa, skull base, atlantoaxial, and epilepsy surgery. The system allows a minimally invasive surgical exposure and provides instant and continual navigational information during surgery. Subjective studies have shown this intraoperative information to facilitate the surgeon's perception of anatomic relations and identification of structures, thus improving surgical safety. Furthermore, in comparison to traditional stereotactic frames, the frameless system has been reported to reduce operative time. The technology involves the use of a localizing mechanical arm to which a pointer or biopsy probe is attached. This localizing arm is hand-held and is therefore only as steady as the surgeon's hand. This precludes the use of the Viewing Wand for functional procedures and for the safe biopsy of small, deep-seated intracranial lesions. Both types of procedures are very dependent on a steady linear approach to the target for a successful outcome. We have designed a simple guidance device that eliminates the risk of unwanted drift or angular movements of the probe as it is advanced toward the target. When used with the Viewing Wand, this device guides the wand biopsy probe along a predetermined, fixed linear trajectory to the intracranial target. We report the successful use of the fixed trajectory guidance device (FTGD) with the Elekta Viewing Wand in a series of 12 patients.

Adolescent↗
PubMed1996

Mixed quantum mechanical/molecular mechanical simulations of chemical reactions in solution and in enzymes by the classical trajectory mapping approach.

We present a practical hybrid quantum mechanical/molecular mechanical approach to study chemical reactions in solution and in enzymes. In this method, referred to as the "Classical Trajectory Mapping" method, trajectories are calculated on the classical potential surfaces and, by using the classical surfaces as a reference state for the actual quantum mechanical ground state potential, the free energy profile of the chemical reaction is obtained by the free energy perturbation technique. This method was applied to proton-transfer reactions both in aqueous solution and in papain. The encouraging results indicate the applicability of our method to chemical reactions in the condensed phase and the biological systems.

Calorimetry↗
PubMed1998

Coping with a partner's cancer: adjustment at four stages of the illness trajectory.

PURPOSE/OBJECTIVES: To study the psychosocial adjustment of partners/spouses of patients with cancer at four specific stages of the illness trajectory time of diagnosis, period of first remission, first recurrence, and period of metastatic disease. DESIGN: A cross-sectional, descriptive survey. SETTINGS: A university cancer center, a private cancer clinic, and a clinic in a large city serving people who are uninsured and unable to pay for their treatment. SAMPLE: 175 partners of patients who were in one of four specific stages of the illness trajectory participated in this study, Various types of cancer were represented. Seventy-seven participants were men, and 98 were women; their mean age was 49 years. METHODS: A survey questionnaire was used to collect data on psychosocial adjustment, specific sources of social support, dyadic adjustment, coping strategies, emotional response, cognitive response, and personal control. FINDINGS: Results indicate that partners of patients who were experiencing a recurrence of their illness or who were in the metastatic stage of the disease were more vulnerable to increased distress and problems of adjustment. Women also reported higher levels of distress than men. Variables that had the most significant direct affect on adjustment were emotional response, cognitive response, family support, and partner cohesion. Coping strategies influenced emotion and cognition. CONCLUSIONS: Caring for partners is essential to promoting quality of life for the patient and the family. IMPLICATIONS FOR NURSING PRACTICE: Assessment, providing an opportunity to express concerns, and referral for psychosocial intervention as necessary are important to promote the highest possible quality of life for partners and patients.

Adaptation, Psychological↗
PubMed1998

Revisiting how the Chronic Illness Trajectory Framework can be applied for persons living with HIV/AIDS.

Over 7 years ago, the Chronic Illness Trajectory Framework was applied to persons living with HIV/AIDS (Nokes, 1991). This article addresses how new information about HIV-infection disease can be interpreted through the Chronic Illness Trajectory Framework. At the time of the first writing, HIV infection was diagnosed indirectly through the presence of antibodies and one or two medications were available to treat the infection. Currently, direct viral testing is used clinically and 18 medications, which can be used in a variety of combinations, should be available by the end of 1998. Although mortality rates from AIDS dropped sharply with the advent of new therapies, current anecdotal reports are indicating that some people, who initially felt much better on the medications, are now developing viral resistance and life-threatening toxicities. Unfortunately, it seems that as we approach the 21st century, information about HIV continues to evolve and another update will then be needed.

Adaptation, Psychological↗
PubMed2002

Developmental trajectories of brain volume abnormalities in children and adolescents with attention-deficit/hyperactivity disorder.

CONTEXT: Various anatomic brain abnormalities have been reported for attention-deficit/hyperactivity disorder (ADHD), with varying methods, small samples, cross-sectional designs, and without accounting for stimulant drug exposure. OBJECTIVE: To compare regional brain volumes at initial scan and their change over time in medicated and previously unmedicated male and female patients with ADHD and healthy controls. DESIGN, SETTING, AND PARTICIPANTS: Case-control study conducted from 1991-2001 at the National Institute of Mental Health, Bethesda, Md, of 152 children and adolescents with ADHD (age range, 5-18 years) and 139 age- and sex-matched controls (age range, 4.5-19 years) recruited from the local community, who contributed 544 anatomic magnetic resonance images. MAIN OUTCOME MEASURES: Using completely automated methods, initial volumes and prospective age-related changes of total cerebrum, cerebellum, gray and white matter for the 4 major lobes, and caudate nucleus of the brain were compared in patients and controls. RESULTS: On initial scan, patients with ADHD had significantly smaller brain volumes in all regions, even after adjustment for significant covariates. This global difference was reflected in smaller total cerebral volumes (-3.2%, adjusted F(1,280) = 8.30, P =.004) and in significantly smaller cerebellar volumes (-3.5%, adjusted F(1,280) = 12.29, P =.001). Compared with controls, previously unmedicated children with ADHD demonstrated significantly smaller total cerebral volumes (overall F(2,288) = 6.65; all pairwise comparisons Bonferroni corrected, -5.8%; P =.002) and cerebellar volumes (-6.2%, F( 2,288) = 8.97, P<.001). Unmedicated children with ADHD also exhibited strikingly smaller total white matter volumes (F(2,288) = 11.65) compared with controls (-10.7%, P<.001) and with medicated children with ADHD (-8.9%, P<.001). Volumetric abnormalities persisted with age in total and regional cerebral measures (P =.002) and in the cerebellum (P =.003). Caudate nucleus volumes were initially abnormal for patients with ADHD (P =.05), but diagnostic differences disappeared as caudate volumes decreased for patients and controls during adolescence. Results were comparable for male and female patients on all measures. Frontal and temporal gray matter, caudate, and cerebellar volumes correlated significantly with parent- and clinician-rated severity measures within the ADHD sample (Pearson coefficients between -0.16 and -0.26; all P values were <.05). CONCLUSIONS: Developmental trajectories for all structures, except caudate, remain roughly parallel for patients and controls during childhood and adolescence, suggesting that genetic and/or early environmental influences on brain development in ADHD are fixed, nonprogressive, and unrelated to stimulant treatment.

Adolescent↗
PubMed1996

Sympathetic nerve trajectories to rat orbital targets: role of connective tissue pathways.

The trajectories of sympathetic nerves projecting to orbital targets were determined in adult rats with intact innervation and following acute sympathetic denervation, neonatal unilateral superior cervical ganglionectomy, or unilateral ganglionectomy on postnatal day 30. Sympathetic nerves were identified by using immunofluorescence for the noradrenergic transmitter enzyme dopamine beta-hydroxylase and by using catecholamine histofluorescence. In rats with intact innervation, sympathetic fibers travel to the orbit in association with the abducens, trochlear, and Vidian nerves. Within the retroorbital and retroocular connective tissue, the fibers redistribute to become associated with sensory-nerve branches of the trigeminal nerve, the orbital vasculature, and the periorbital sheath. Fibers reach their targets by traversing variable amounts of connective tissue of the periorbitum, the orbital septa, and the striated muscle epimysia. Following neonatal ganglionectomy, intracranial fibers of contralateral origin enter the orbit by traveling through connective tissue of the optic nerve meninges and lining the anterior lacerated foramen. These fibers travel independent of the trochlear, abducens, and Vidian nerves, but, otherwise, they use the same orbital pathways as those employed in the intact animal. In animals ganglionectomized on postnatal day 30, fibers enter the posterior portion of the orbit primarily via the optic foramen; they travel only short distances and end blindly in the periorbital sheath. These findings indicate that fascial structures are a major component of the pathways that guide sympathetic fibers to their appropriate targets both in normal development and during reinnervation following neonatal ganglionectomy. Because orbital connective tissues are termination sites of abortive fiber sprouting in older rats, developmental changes in the properties of these tissues may contribute to the absence of pathway formation in the mature animal.

Adrenergic Fibers↗
PubMed1999

Selection of high-definition 2D virtual profiles with multiple RF pulse excitations along interleaved echo-planar k-space trajectories.

A method for spatially selective excitation of 2D RF profiles is reported. The method makes use of multiple shots to traverse interleaved echo-planar trajectories in 2D k space during each RF pulse excitation. Results from each of the interleaved excitations are summed, with the net effect being the excitation of a virtual profile. The method allows for the excitation of high-definition 2D profiles with standard gradient hardware. Signal to noise is enhanced by a factor equal to the square root of the number of interleaved excitations, compared with a single-shot excitation. Potential applications for volume-localized spectroscopy, functional MRI, and high-resolution reduced-field-of-view imaging are discussed.

Echo-Planar Imaging↗