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PubMed2000

The strain magnitude and contact guidance determine orientation response of fibroblasts to cyclic substrate strains.

When grown in a substrate subjected to cyclic stretching, most types of cells change orientations. This cell orientation response (COR) has been shown to be driven by axial substrate strain (the strain beneath and along a cell's long axis). However, it remains unclear whether COR depends on the strain direction (tension vs compression). Furthermore, in vitro COR is paradoxical, since in vivo fibroblasts align along collagen fibers and hence the stretch direction. We hypothesized that COR does not depend on the surface strain direction, and that contact guidance provided by microgrooves can maintain cell alignment in the presence of cyclic stretching. Human skin fibroblasts were cultured on compliant smooth and microgrooved surfaces in silicone dishes. Cyclic uniaxial tensile and compressive strains (4%, 8% and 12%) were applied on the dishes at 1 Hz for 24 h. Cell orientation distributions were determined and compared using the Kolmogorov-Smirnov test. Significant differences were found between each of cell orientation distributions with the applied strains and that without strains (p < 0.05). Nevertheless, no significant differences were found between two cell orientation distributions for each pair of opposite strains applied (for 4%, p = 0.33; for 8%, p = 0.18; and for 12%, p = 0.32). Moreover, fibroblasts grown in microgrooves aligned in the groove direction and remained so after 8% cyclic stretch. Thus, this study showed that COR is the cells' avoidance to substrate deformation (i.e., strain-direction independent). It also suggested that the failure of fibroblasts to change orientations in vivo may result from the contact guidance provided by collagen fibers.

Actins↗

PubMed2001

Thallium-201 myocardial imaging at rest in male orienteers and other endurance athletes.

During the period 1979 to 1992, 16 sudden unexpected cardiac deaths were known to have occurred in young Swedish orienteers. Autopsy indicated myocarditis to be the most frequent finding, most often combined with extensive myocardial fibrosis. The aim of the present investigation was to explore whether young male orienteers show a higher frequency than other young elite endurance athletes (controls) in the occurrence of Thallium-201 myocardial perfusion defects at rest, suggestive of fibrosis evoked by myocarditis. Thallium-201 perfusion abnormalities at rest were more frequently found in the controls than in the orienteers (26% vs. 12%, p=0.03). Uneven Tl-201 perfusion was associated with left ventricular mass (r=0.32, r=0.24, p<0.01, p=0.02) and body weight (r=0.30, r=0.31, p<0.01, p=0.03) in orienteers and controls, respectively. Echocardiographic left ventricular wall motion abnormalities were found in 11 athletes (9 orienteers and 2 controls) but only two displayed an abnormal Thallium-201 perfusion scan at rest. Perfusion abnormalities at rest did not occur more frequently in the orienteers but were commonly found in both groups of apparently healthy athletes making it futile to discern abnormals from normals. Thallium-201 perfusion aberrations were not associated with left ventricular wall motion abnormalities obtained by echocardiography.

Adult↗

PubMed1990

Thermal and physiologic responses to 1200-MHz radiofrequency radiation: differences between exposure in E and H orientation.

Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 1200-MHz continuous wave radiofrequency radiation in both E and H orientations (long axis of animal parallel to electric or magnetic field, respectively). Power densities were used that resulted in equivalent whole-body specific absorption rates of approximately 8 W/kg in both orientations (20 mW/cm2 for E and 45 mW/cm2 for H). Exposure was conducted to repeatedly increase colonic temperature from 38.5 to 39.5 degrees C in both orientations in the same animal. Irradiation in E orientation resulted in greater colonic, tympanic, left subcutaneous (side toward antenna), and tail heating. The results indicated a more uniform distribution of heat than that which occurred in previous experiments of 2450-MHz irradiation in E and H orientation. A lack of significant differences in blood pressure and heart rate responses between exposures in the two orientations in this study suggest that greater peripheral heating, as was seen in the earlier study of 2450 MHz, is necessary for these differences to occur.

Animals↗

PubMed2003

Orientation invariance in visual object priming depends on prime-target asynchrony.

Two experiments are reported in which orientation effects on visual object recognition latency were examined. In Experiment 1, we assessed picture-naming performance as a function of image-plane stimulus orientation and found increasing response times with increased misorientation of the stimulus. In Experiment 2, we examined the repetition priming effect on the identification of upright targets as a function of prime orientation. With time delays of 100, 200, or 500 msec between the onset of the prime and that of the target (i.e., stimulus onset asynchrony [SOA]), the magnitude of the priming effect decreased with increasing misorientation of the prime. These results contrast with the orientation-invariant priming effects reported in some previous repetition priming studies. These investigations all used relatively long prime-target SOAs. Confirming the crucial role of the latter variable, Experiment 2 shows that the magnitude of the repetition priming effect is invariant across prime orientations with an SOA of 1,000 msec. The possible implications of the present observations with respect to the issue of orientation invariance versus dependency of the visual object recognition processare discussed.

Adult↗

PubMed2002

The beholder's share in the perception of orientation of 2-D shapes.

A considerable amount of research demonstrates that people perceive cardinal orientations (horizontal and vertical) more accurately than other orientations; this is termed the oblique effect. We investigated the interaction of this effect with the degree of elongation of the stimulus. Our stimuli were ellipses with a wide range of aspect ratios, varying from a circle (aspect ratio = 1) to a line (aspect ratio = 123.5). The task was to set a probe line in the same orientation as the long axis of the ellipse. In our first experiment, we determined that performance is degraded as the aspect ratio decreases; furthermore, the bias and response variability are linearly related to a transformation of aspect ratio (roundness). We found significant individual differences; the results show high within-subjects correlations and low between-subjects correlations. In our second experiment, we had observers judge the orientation of circles randomly mixed in with ellipses of low aspect ratio. The observers demonstrated intrinsic preferences and generated reproducible distributions of orientation settings with idiosyncratic profiles. These distributions predict the influence on the response to ellipses with an aspect ratio higher than one and can be considered as the beholder's share in the perception of shape orientation.

Adult↗

PubMed2004

Endogenous temporal orienting of attention in detection and discrimination tasks.

Endogenous temporal-orienting effects were studied using a cuing paradigm in which the cue indicated the time interval during which the target was most likely to appear. Temporal-orienting effects were defined by lower reaction times (RTs) when there was a match between the temporal expectancy for a target (early or late) and the time interval during which the target actually appeared than when they mismatched. Temporal-orienting effects were found for both early and late expectancies with a detection task in Experiment 1. However, catch trials were decisive in whether temporal-orienting effects were observed in the early-expectancy condition. No temporal-orienting effects were found in the discrimination task. In Experiments 2A and 2B, temporal-orienting effects were observed in the discrimination task; however, they were larger when temporal expectancy was manipulated between blocks, rather than within blocks.

Attention↗

PubMed1988

Nursing role orientation of three groups: from the naive to the realistic.

A comparison was made of the responses of nursing students, non-nursing students, and nurses to an instrument designed to measure nursing-role orientations. In addition, the nursing students were evaluated on this instrument before and after taking a professional role development course. Factor analyses indicated that, in general, this instrument did not measure the orientations as planned; however, it did reveal a "nursing awareness" continuum. The factors generated by the responses of the non-nursing students reflected naiveté regarding nursing, while the nurses were realistic. The nursing students were similar to the non-nursing students before taking the professional role development course and similar to the nurses after the course. Although there were no significant pretest-posttest differences, the nursing students' factors indicated greater knowledge of nursing professionalism after completing the course. Nursing role orientations should not be considered fixed entities, but conceptions affected by nursing experience. The failure of the instrument to measure nursing role orientations as intended supports suggestions that nursing role orientations have changed in recent years. More "modern" orientations may be appropriate at this time.

Adolescent↗

PubMed1994

Experienced faculty orientation offerings: do they meet faculty needs?

The purposes of this descriptive study were to identify existing orientation protocols for seasoned nurse faculty who change academic positions and which orientation protocols these faculty perceived helpful. Subjects were drawn from 460 NLN-accredited generic baccalaureate programs. All subjects (N = 372) had a minimum of three years' prior teaching experience and were employed at the institution within 1990-91 and 1991-92. A two-part questionnaire, adapted from Mills (1983), was used. Some form of orientation was offered to 81% of the sample, with 27% reporting an orientation of less than one day. Topics addressed by orientation programs for the majority of the sample included conceptual framework and curriculum; teaching and library resources; and organizational structure. Areas not addressed included introduction to local nursing organizations and the community in general. Results suggest that experienced faculty receive some form of orientation. The scope is limited, with such topics as clinical placement and student evaluation omitted.

Adult↗

PubMedDate not supplied

Sexual orientation: its relevance to occupational science and the practice of occupational therapy.

This article examines how sexual orientation may be relevant to the study of occupations and the practice of occupational therapy. It is suggested that a lesbian, gay, or bisexual orientation may influence the occupations in which a person engages, the symbolic interpretation of those occupations, and the environmental contingencies of those occupations, and thus is an appropriate topic for occupational scientists to address. With the use of clinical reasoning studies and literature on authentic occupational therapy, it is argued that a person's lesbian, gay, or bisexual orientation may be relevant to the therapeutic process if therapists are to truly achieve an intersubjective understanding of the patient's world and create an environment in which the patient is able to live a meaningful life. Given this argument as a foundation, the article explores why sexual orientation may be overlooked in some of the theoretical perspectives that guide practice. The narrative perspective on identity is introduced as one potentially valuable way that occupational therapy researchers and practitioners may understand sexual orientation and its relationship to occupation. Specifically it is suggested that sexual orientation may be understood, in part, as a symbolic theme of meaning that informs values and convictions that may then be expressed in one's choice of occupations.

Activities of Daily Living↗

PubMed1992

Comprehensive orientation: the road to retention.

This study evaluated the relationship between the type of orientation received by registered nurse employees in the hospital and the turnover behavior of these employees within the first 12 months of employment. The comprehensiveness of the orientation programs of six major metropolitan hospitals was evaluated using a structure evaluation tool. The records of registered nurses who attended the September 1988 orientation programs at these hospitals were examined to identify their employment status and pertinent demographic data one year from the date of participation in orientation. Data were analyzed to determine if an association existed between the comprehensiveness of orientation and employment status. The data revealed no significant difference between "stayers" and "leavers" after participation in orientation programs meeting greater than 80 percent of the criteria for program comprehensiveness. Significantly more "leavers" than "stayers" resulted from participation in programs meeting greater than 90 percent of the criteria for program comprehensiveness.

Chi-Square Distribution↗

PubMed1998

[Effects of spatial orientation on attention reaction time during pointing movement towards visual direction].

In the present study, it was consequently proposed to investigate how the spatial orientation of attention made by the explicit and implicit components of advance information, affected the reaction time (RT) performances. Subjects performed a simple RT task with an orientation cue and two choice RT situations, the one with a neutral cue and the other with a primed cue. The motor task to be performed consisted of pointing towards a visual target. The mechanisms involved in the orientation of attention were studied on the one hand by analysing the effects of the preparatory signal, which explicitly oriented the subjects' attention towards the forthcoming target position, and on the other hand, by examining whether the reinforced probability of warning stimulus(WS) and imperative stimulus (IS) being compatible affected the subjects' performances, i.e., whether they detected and made use of the information implicitly conveyed that there existed a bias in favour of the probability that IS would appear in the direction predicted by WS. The results of this study show that the subjects shortened their RTs by using both the explicit(auditory) and the implicit(probability-related) information with which they were provided prior to performing the movement. These data on the effects of the oriented auditory signal on the reaction times indicate that in our experiments, by orienting their attention depending on the position of the stimuli, the subjects were able to reduce their reaction times. The significant correlation found to exist here between the level of probability associated with the position of the WS and the choice RT values indicates that also the implicit information as to the WS-IS compatibility was taken into account by the subjects in all the situations.

Adult↗

PubMed2000

Graphic displays: the effects of orientation on the tangible perception of histograms and pie charts.

Two studies designed to investigate the ability of blind subjects to interpret tangible graphic displays of data at varying degrees of orientation are reported. In the first experiment visually handicapped children were required to interpret histograms and pie charts presented at two different orientations. Horizontally oriented histograms were found to have a significant advantage over vertically oriented histograms, but there was no effect of orientation on pie charts. In the second study horizontally and vertically oriented histograms were again compared using a subject sample comprised only of congenitally or very early blind children. The results confirmed the superiority of horizontally presented histograms over the more common vertical display.

Blindness↗

PubMed2003

Involvement of the glycoproteic meshwork of cervical mucus in the mechanism of sperm orientation.

BACKGROUND: The aim of this study was to investigate the influence of the solid phase of the mucus hydrogel in facilitating the upward movement of spermatozoa during the menstrual cycle. METHODS: A total of 171 sperm migration experiments using 47 selected ovulatory mucus samples were performed in vitro in tubes of various shape and diameter. Physical constraints applied to cervical mucus combined with scanning electron microscopy (SEM) techniques permitted analysis of the mechanism of sperm orientation within cervical mucus submitted to capillary constraints simulating the various conditions of sperm orientation in vivo. RESULTS: The results support the theory according to which spermatozoa entering the cervical canal are constrained to follow the oriented micellar lines of strain. Stretched ovulatory mucus exhibits noticeable prevalent orientation of most filaments aligned in a manner roughly parallel to the traction axis. By contrast, even after strong stretching applied to luteal-type mucus and longer contact periods, the alignment of glycoproteic meshes was not sufficiently marked to allow spermatozoa to orient themselves and to move rapidly. The results are discussed as a function of the variations occurring in the three-dimensional macromolecular arrangement of the glycoproteic framework subjected to flow constraints. CONCLUSIONS: The study confirms that there is a close relationship between the three-dimensional arrangement of the mucus framework and the ability of spermatozoa to move rapidly in a given direction. The high resolution and three-dimensional aspect of SEM micrographs support the correlation of sperm orientation with current data on rheologic properties of biologic hydrogels.

Cervix Mucus↗

PubMed2004

Adaptation of plants to altered shoot orientation relative to the gravity vector.

Wheat Triticum aestivum L., carrots Daucus carota L., Chinese cabbage Brassica pekinensis Rupr., and African marigold Tagetes patula L. were grown at natural and inverted orientation in the Earth gravitational field. Light vector was set unidirectional or opposite directional relative to the gravity vector. Shoot orientation relative to the gravity vector was set natural or invert. Plants grew in the special pots furnished with plane or cylindrical hydrophilic porous membranes. The membrane allowed to stabilize a water potential in the root zone at the fixed level. Seeds were put into a fiber ion-exchange artificial soil overlaying horizontal hydrophilic plates of porous titanium or anchored to porous metal-ceramic tubes. Plants grew at the PPF level 550 +/- 20 micromoles/(m2 s) during 24-hr lighting and at the water potential level at the membrane surface (-1.00) +/- 0.08 kPa. Normal plants were obtained both at the natural and at the inverse shoot orientation in the all experiments. The wheat plants were yielded healthy germinating seeds no matter plant orientation. In the inverse orientation, no negative influence for plant biomass accruing was marked, but the increasing of shoot to root mass ratio was considerable. However carrot root crop mass decreasing was not revealed in the inverse orientation. The results demonstrated substantial dependence of morphological and physiological characteristics of higher plants on the gravity factor.

Biomass↗

PubMed1991

Electrostatic orientation of the electron-transfer complex between plastocyanin and cytochrome c.

To understand the specificity and efficiency of protein-protein interactions promoting electron transfer, we evaluated the role of electrostatic forces in precollision orientation by the development of two new methods, computer graphics alignment of protein electrostatic fields and a systematic orientational search of intermolecular electrostatic energies for two proteins at present separation distances. We applied these methods to the plastocyanin/cytochrome c interaction, which is faster than random collision, but too slow for study by molecular dynamics techniques. Significant electrostatic potentials were concentrated on one-fourth (969 A2) of the plastocyanin surface, with the greatest negative potential centered on the Tyr-83 hydroxyl within the acidic patch, and on one-eighth (632 A2) of the cytochrome c surface, with the greatest positive potential centered near the exposed heme edge. Coherent electrostatic fields occurred only over these regions, suggesting that local, rather than global, charge complementarity controls productive recognition. The three energetically favored families of pre-collision orientations all directed the positive region surrounding the heme edge of cytochrome c toward the acidic patch of plastocyanin but differed in heme plane orientation. Analysis of electrostatic fields, electrostatic energies of precollision orientations with 12 and 6 A separation distances, and surface topographies suggested that the favored orientations should converge to productive complexes promoting a single electron-transfer pathway from the cytochrome c heme edge to Tyr-83 of plastocyanin. Direct interactions of the exposed Cu ligand in plastocyanin with the cytochrome c heme edge are not unfavorable sterically or electrostatically but should occur no faster than randomly, indicating that this is not the primary pathway for electron transfer.

Amino Acid Sequence↗

PubMedDate not supplied

Control of cellular orientation in two-dimensional tissue formation. Surface topologic effect of collagen fibers on endothelialization.

The authors studied the effect of polymorphous states of collagen on in vitro cellular orientation of bovine aortic endothelial cells (ECs). Little orientation of adherent ECs was observed on a nonoriented collagen coated surface, irrespective of culture period. Only ECs that adhered to fiber bundles 10 microns in diameter exhibited cellular elongation or alignment. The collagen membrane with highly oriented fine fibers provided no cellular alignment for ECs in sparse culture. Resultant confluent monolayers, however, were characterized by cellular orientation, suggesting that surface microtopology of collagen induces cellular orientation on incubation. Control of cellular orientation would be an elementary requirement for cell seeding technology leading to hybrid artificial organs.

Animals↗

PubMed1991

[Public health nursing's role in a crisis stage: people-oriented functions are obsolete].

The nurses and the public health nurses identified mostly individuals as the focus of their service although also families and groups are increasingly receiving services. Orientation towards communities or environments is rather rare. The modes of nursing practice of nurses differentiated from each other quite a lot. On the basis of the results two main modes had been identified: organization oriented and people oriented mode. The organization oriented made is somewhat stereotyped, rather guided by rules and regulations than by the needs of people. The people oriented mode is based on the needs of clients. The needs are being assessed openly and by exploring the situation. Client-centred objectives are being established more often and the interventions are better identified than in the organization oriented mode. The interventions are focused to support the resources of the clients f.e. their own thinking processes and other abilities. On the basis of the interviews it seems to be that nursing practice is in the middle of a transition period. The accountability for one's practice is being gradually accepted. Nursing practice is developing to a more individual direction and the viewpoints of people will be better understood.

Community Health Services↗

PubMed1991

Streamlining orientation for hemodialysis nursing: a competency-based approach.

Orientation of a nephrology nurse in a hemodialysis setting is a complex process; often stressful for the learner and time consuming for the educator. The extent of orientation depends upon individual learning needs and previous clinical experience. The competency-based approach to orientation in hemodialysis is comprehensive, efficient, and cost-effective. Modular in design, it is adaptable to varying levels of orientation needs. Based on andragogical theory, it is goal-oriented and learner-directed. A manual has been developed to facilitate a competency-based orientation in hemodialysis. The manual is an outcome-driven tool designed to integrate the nursing process with dialysis technology. The focus is maximization of nephrology nursing care resulting in enhanced patient outcomes.

Competency-Based Education↗