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At least 19 recordsLinked to original sources
PubMed1978

Studies on the orientations of the mitochondrial redox carriers. II. Orientation of the mitochondrial chromophores with respect to the plane of the membrane in hydrated, oriented mitochondrial multilayers.

Orientations of the active site chromophores of the mitochondrial redox carriers have been investigated in hydrated, oriented multilayers of mitochondrial membranes using optical and EPR spectroscopy. The hemes of cytochrome c oxidase, cytochrome c1, and cytochromes b were found to be oriented in a similar manner, with the normal to their heme planes lying approximately in the plane of the mitochondrial membrane. The heme of cytochrome c was either less oriented in general or was oriented at an angle closer to the plane of the mitochondrial membrane than were the hemes of the "tightly bound" mitochondrial cytochromes. EPR spectra of the azide, sulfide and formate complexes of cytochrome c oxidase in mitochondria in situ obtained as a function of the orientation of the applied magnetic field relative to the planes of the membrane multilayers showed that both hemes of the oxidase were oriented in such a way that the angle between the heme normal and the membrane normal was approx. 90 degrees.

Animals↗
PubMed1979

Studies of the orientation of the mitochondrial redox carriers. III. Orientation of the gx and gy axes of the hemes of cytochrome oxidase with respect to the plane of the membrane in oriented membrane multilayers.

The EPR absorption properties of the hemes of cytochrome oxidase and their liganded derivatives were examined in oriented multilayers from isolated oxidase, mitochondrial membranes and membrane fragments of a bacterium, Paracoccus denitrificans. The hemes of the oxidase in all the systems investigated were oriented normal to the plane of the multilayers. The directions of the g signals corresponding to the gx and gy axes of the g tensor were found to be different in low-spin ferric heme in fully oxidized oxidase and in half-reduced liganded oxidase. It is suggested that this different orientation of gx and gy in fully oxidized oxidase and half-reduced liganded oxidase arises because the respective EPR signals belong to two different hemes, those of cytochrome a and a3.

Animals↗
PubMed1992

Orientational distribution of spin-labeled actin oriented by flow.

Previous studies on spin-labeled F-actin (MSL-actin), using saturation transfer electron paramagnetic resonance (ST-EPR), have demonstrated that actin has submillisecond rotational flexibility and that this flexibility is affected by the binding of myosin and its subfragments. This rotational flexibility does not change during the active interaction of myosin heads, actin, and adenosine triphosphate. However, these ST-EPR studies, performed on randomly oriented actin, would not be sensitive to orientational changes on the millisecond time scale or slower. In the present study, we have clarified these results by performing conventional EPR experiments on MSL-actin oriented by flow to detect changes in the orientational distribution. We have determined the orientational distribution of the spin labels relative to the magnetic field (flow direction) by comparing experimental EPR spectra to simulated EPR spectra corresponding to known orientational distributions. Spectra acquired during flow indicate two populations of probes: a highly ordered population and a disordered population. For the ordered population (28% of the total spin concentration), the angle between the actin filament axis and the nitroxide z axis (theta) fits a Gaussian distribution centered at 32.0 +/- 0.9 degrees, with a full width at half maximum of 20.7 +/- 3.9 degrees. The angle between the nitroxide x axis and the projection of the field in the xy plane (phi) is centered at 37.5 +/- 9.2 degrees with a full width of 24.9 +/- 10.7 degrees. This orientational distribution is not significantly changed upon the binding of phalloidin or myosin subfragment 1 (S1), indicating that these proteins do not affect the axial orientation of actin subunits. Spectra of spin-labeled S1 (MSL-S1) bound to actin oriented by flow have about the same orientational distribution as MSL-S1 bound to actin in oriented fibers. Thus, the oriented fraction of flow-oriented actin filaments has nearly the same high degree of alignment as the actin filaments in muscle fibers.

Actins↗
PubMed1988

Predicting talocalcaneal joint orientations from talocalcaneal/talocrural joint orientations.

The purpose of this investigation was to determine the capacity of talocalcaneal/talocrural joint orientations to predict talocalcaneal (TC) joint orientations. A custom designed orientation-loading fixture was used to position the calcaneus and shank with six degrees of freedom, and to apply loads in three orthogonal directions. Three reference pins were rigidly mounted in the calcaneus, talus, and shank segments to provide position data in 243 test situations. Test data were fitted to statistical models using analysis of variance. The models were then used to determine the capacity to predict talus positions from shank positions, both with respect to the calcaneus. Results indicated large between and within specimen variation and was attributed to individual joint morphology. It was concluded that (a) eversion-inversion orientations of the TC/talocrural joint were not always accurate indicators of TC joint orientations, (b) abduction-adduction orientations of the combined joint had the greatest overall influence on TC orientations (thus, monitoring eversion-inversion and abduction-adduction orientations of the combined joint would be more valuable in predicting pronation-supination positions than monitoring only eversion-inversion orientations), and (c) foot categories based on TC and TC/talocrural joint morphology should be developed. They would provide more accurate prediction for specimen foot orientations than prediction from overall average values.

Adult↗
PubMed1991

Orientation in birds. Magnetic orientation and celestial cues in migratory orientation.

Young birds on their first migration possess innate information on the direction of their migration route. It is represented twice, using both celestial rotation and the geomagnetic field as references. These two systems, together with information provided by factors associated with sunset, interact in a complex way to establish the migratory direction. During ontogeny, celestial rotation appears to be dominant; during migration, however, celestial cues appear to be controlled by the magnetic field.--The factors associated with sunset--the view of the setting sun and the characteristic pattern of polarized light--are important secondary cues which seem to derive their directional significance from the magnetic field. Their role appears to be more variable, with possible species-specific differences. During spring migration and later autumn migrations, flying in the migratory direction is complemented by navigational processes which enable the birds to return to a specific home site known from previous stays.

Animals↗
PubMed1986

Comparison of theoretically oriented and patient-oriented behavioral science courses.

Effective teaching of medical behavioral science is an important challenge for psychiatrists. Two behavioral science courses taught at different times at the Yale University School of Medicine are described: a theoretically oriented course emphasizing symbolic function, primary source reading, and conceptual thinking and a patient-oriented course emphasizing the relevance of behavioral science to the practice of medicine, taught primarily by consultation-liaison psychiatrists. Students' evaluations of the two courses during the fifth year each course was taught were compared. The students' acceptance of the patient-oriented course was dramatically greater than that of the theoretically oriented course. The class mean scores on the behavioral science subtest of the Part I examination of the National Board of Medical Examiners during the last four years that the courses were taught were compared. The mean scores of the classes that had taken the patient-oriented course were significantly higher than those of the classes that had taken the theoretically oriented course. The mean score for the class that took the fifth year of the patient-oriented course was 52 points higher than the mean score for the class that took the fifth year of the theoretically oriented course. The authors concluded that the skills that consultation-liaison psychiatrists use every day in their work may be exactly those that are useful in teaching a successful behavioral science course for medical students.

Behavioral Sciences↗
PubMed1989

[Action-oriented versus state-oriented reactions to experimenter-induced failures].

The present study assessed different effects of action-oriented versus state-oriented styles of coping with failure on achievement-related performance and cognition. In a learned helplessness experiment, students were exposed to an academic failure situation and were then tested on a series of problem-solving tasks, either immediately after the pretreatment or after a delay of 24 hours. Performance and cognitive concomitants were measured during both experimental periods. Results demonstrated that action orientation was associated with self-immunizing cognitions during helplessness training. Action-oriented participants improved their performance level even after repeated failure feedbacks. Moreover, action-oriented students assigned to the delayed test condition responded with increased striving for success and showed performance increments, even in comparison with control subjects. In contrast, state-oriented participants developed symptoms of helplessness and showed impaired performance during failure inductions. In later tests on problem-solving tasks, state-oriented groups responded with increased fear of failure. Independent of immediate or delayed test conditions, they soon lapsed into new performance decrements.

Achievement↗
PubMed1991

Relation of cortical cell orientation selectivity to alignment of receptive fields of the geniculocortical afferents that arborize within a single orientation column in ferret visual cortex.

Neurons in the primary visual cortex of higher mammals are arranged in columns, and the neurons in each column respond best to light-dark borders of particular orientations. The basis of cortical cell orientation selectivity is not known. One possible mechanism would be for cortical cells to receive input from several lateral geniculate nucleus (LGN) neurons with receptive fields that are aligned in the visual field (Hubel and Wiesel, 1962). We have investigated the relationship between the arrangement of the receptive fields of geniculocortical afferents and the orientation preferences of cortical cells in the orientation columns to which the afferents provide visual input. Radial microelectrode penetrations were made into primary visual cortex of anesthetized adult sable ferrets. Cortical cells were recorded throughout the depth of the cortex, and their orientation preferences were determined. Cortical cell responses were then eliminated by superfusion of the cortex with either kainic acid (Zahs and Stryker, 1988) or muscimol. After the drug treatment, responses from many single units with distinct receptive fields were recorded. These responses were presumed to be those of geniculocortical afferents, because they had the response properties characteristic of LGN neurons, and because they could be recorded only in cortical layers that receive geniculate input. In 16 of 18 cases, the afferent receptive fields recorded in a single penetration covered an elongated region of visual space. In these penetrations, the best-fit line through the centers of the afferent receptive fields generally paralleled the preferred orientation of cortical cells recorded at the same site in cortex. These results are consistent with the Hubel and Wiesel (1962) model for the construction of oriented visual cortical receptive fields from geniculate inputs with aligned receptive fields.

Afferent Pathways↗
PubMed1975

The orientation anisotropy and orientation constancy: a visual evoked potential study.

Two experiments were conducted on the orientation anisotropy in which averaged visual evoked potentials (VEPs) were recorded from the occipital scalp. The first experiment confirmed the findings of Maffei and Campbell (1970) that obliquely oriented gratings alternated back and forth produced smaller-amplitude VEPs than when the gratings were oriented horizontally or vertically. Since no asymmetry was found in VEPs produced by a Julesz figure presented under identical conditions, it was concluded that direction of displacement could not have been contributing to the effect. In a second experiment head tilt of the subject was manipulated together with grating orientation and the results indicated that the orientation anisotropy is retinally rather than gravitationally referenced. It was concluded that the site of orientation constancy is located either at higher levels of the primary visual system or in the second visual system.

Adult↗
PubMed1985

Orientation sensitivity and texture segmentation in patterns with different line orientation.

Orientation sensitivity (OS) and the ability of human subjects to discriminate structured areas of different texture orientation (DOT) were investigated using line arrays of varying line length. In general, OS was mediated by shorter lines than was DOT; lines can be distinguished by their orientation before they give the impression of a texture border between adjacent regions with lines differing in orientation. This difference was found to hold over a range of retinal eccentricities from 5 degrees nasal to 30 degrees temporal. Decreasing visual acuity, associated with increasing distance from the fovea, cannot, however, account for the higher threshold of DOT, even taking into account that DOT requires a larger area for analysis than OS. When angle of orientation between adjacent texture areas was varied instead of line length, DOT thresholds at different retinal locations were reached at similar values. The difference between OS and DOT, found consistently at all retinal positions, suggests that they are mediated by distinct neural mechanisms.

Adolescent↗
PubMed1985

Measurement of erythrocyte orientation in flow by spin labeling II--phenomenological models for erythrocyte orientation rate.

We present two phenomenological models describing the flowing erythrocyte orientation rate. The first concerns the onset of a stable orientation in a very dilute erythrocyte suspension. It is based on a simple formula for erythrocyte elongation as a function of shear stress, and we assume that beyond a threshold of elongation, erythrocytes take on a stable orientation, while below this threshold, they have a flipping motion. We extend this model to high hematocrit values assuming that the effect of red cell collisions imposes a random moment to each erythrocyte, shifting it from its stable orientation. We obtain an approximate expression for erythrocyte orientation rate as a function of shear rate and then we compare these results to our experimental data in part III of this series.

Biomechanical Phenomena↗
PubMed1991

Problem-oriented training promotes spontaneous analogical transfer: memory-oriented training promotes memory for training.

Spontaneous analogical transfer is the use of information from one problem to solve another problem, without an explicit hint to use the previous information. The results of five experiments were that if subjects tried to solve a training problem before hearing its solution, or tried to explain a training story's solution before hearing the correct explanation, spontaneous transfer was more likely than it was if subjects had studied the same training passage for memory before hearing its solution or explanation. The advantage of problem-oriented processing over memory-oriented processing occurred even though solution attempts nearly always failed, and the advantage was not reduced if the target problem was tested 15 min later rather than immediately after training. We propose that problem-oriented processes performed at study are appropriate processes to use at test. Further support for the account comes from subjects' memory for the training passages; the advantage for problem-oriented processing on solution tasks was mirrored by an equally substantial advantage for the memory-oriented subjects on a recall task.

Adult↗
PubMed1975

The effects of lesions of the superior colliculus on locomotor orientation and the orienting reflex in the rat.

The effects of bilateral removal of the superior colliculus or visual cortex on visually guided locomotor movements in rats performing a brightness discrimination task were investigated directly with the use of cine film. Rats with collicular lesions showed patterns of locomotion comparable to or more efficient than those of normal animals when approaching one of 5 small doors located at one end of a large open area. In contrast, animals with large but incomplete lesions of visual cortex were distinctly impaired in their visual control of approach responses to the same stimuli. On the other hand, rats with collicular damage showed no orienting reflex or evidence of distraction in the same task when novel visual or auditory stimuli were presented. However, both normal and visual-decorticate rats showed various components of the orienting reflex and disturbance in task performance when the same novel stimuli were presented. These results suggest that although the superior colliculus does not appear to be essential to the visual control of locomotor orientation, this midbrain structure might participate in the mediation of shifts in visual fixation and attention. Visual cortex, while contributing to visuospatial guidance of locomotor movements, might not play a significant role in the control and integration of the orienting reflex.

Acoustic Stimulation↗
PubMed1985

[Cardiac anxiety syndrome. Etiologic significance of orientation crises and orientation conflicts and their consequences for therapeutic practice].

In the framework of a phenomenological approach to cardiac neurosis the author investigated 20 patients suffering from this disease regarding their kind of communication disorder and conflicts in order to find out the main conditions for etiology. This study is based on the conception of so-called "Anthropological-integrative Psychotherapy" developed by D. Wyss. He conceptualized fundamental structures of communication representing the structural aspect of a psychosomatic disease and modi of communication in order to show its dynamic aspect. The purpose of this investigation was to examine disproportions, deficiencies, compensatory hypertrophy and conflicts in the six fundamental structures of communication (Living Space, Orientation, Order, Time, Body, Performance). In accordance with many other publications separation anxiety, ambivalence between tie and separation, aggressive restraint, sexual disorders and conflicts in the structure of "performance" are confirmed as significant etiological factors. In addition, conflicts, crises and deficiency of orientation have proved to be of major importance. This is the essential result of this study and an important new contribution to our understanding of cardiac neurosis. The therapies of 3 patients suffering from cardiac neurosis are reviewed to illustrate the three main kinds of disorders in orientation. Finally the therapeutic consequences are discussed. The constitution of new orientation in an intersubjective and dialogic process seems to be an essential aim for psychotherapeutic treatment of cardiac neurosis.

Adaptation, Psychological↗
PubMed1979

The orientational freedom of molecular probes. The orientation factor in intramolecular energy transfer.

The measurement of the efficiency of Förster long-range resonance energy transfer between donor (D) and acceptor (A) luminophores attached to the same macromolecular substrate can be used to estimate the D-A separation, R. If the D and A transition dipoles sample all orientations with respect to the substrate (the isotropic condition) in a time short compared with the transfer time (the dynamic averaging condition), the average orientation factor less than K2 greater than is 2/3. If the isotropic condition is not satisfied but the dynamic averaging condition is, upper and lower bounds for less than K2 greater than, and thus R, may be obtained from observed D and A depolarizations, and these limits may be further narrowed if the transfer depolarization is also known. This paper offers experimental protocols for obtaining this reorientational information and presents contour plots of less than K2 greater than min and less than K2 greater than max as functions of generally observable depolarizations. This permits an uncertainty to be assigned to the determined value of R. The details of the D and A reoreintational process need not be known, but the orientational distributions are assumed to have at least approximate axial symmetry with respect to a stationary substrate. Average depolarization factors are derived for various orientational distribution functions that demonstrate the effects of various mechanisms for reorientation of the luminophores. It is shown that in general the static averaging regime does not lend itself to determinations of R.

Energy Transfer↗
PubMed1991

Stimulus-response compatibilities between vertically oriented stimuli and horizontally oriented responses: the effects of hand position and posture.

Stimulus-response (S-R) compatibility effects between vertically oriented stimuli (above or below fixation) and horizontally oriented responses (left or right switch deflections by a single hand) have been shown to depend both on which hand responds (Bauer & Miller, 1982) and on the location at which the response is made (eccentricity on a frontoparallel line; Michaels, 1989). In the latter study, hand position and hand posture were confounded, so it is unclear which variable determined the compatibility effect. In Experiment 1, the importance of effector position was tested. Vertically oriented stimuli were paired with a horizontal response solicited at different locations but always involving the same hand posture. Compatibility effects emerged, and their direction depended on position. In Experiment 2, the compatibilities were not evident in a simple reaction time paradigm, so the effect was not due to differential ease of responses. In Experiment 3, a change in hand posture (palm up or palm down) at the same location (the body midline) also affected the compatibilities. It was concluded that the S-R compatibility of orthogonally oriented stimuli and responses is influenced by (1) which hand responds, (2) the location of that hand, and (3) its posture. The results imply that both postural and positional states of the action system affect S-R compatibility.

Fixation, Ocular↗
PubMed1978

[Orientation of the cleavage spindles in pulmonate mollusks. I. The role of the form of the blastomeres in 2d cleavage spindle orientation].

In the normal two-celled embryos of various pulmonate molluscs, the orientation of spindles characteristic of metaanaphase is being frequently established gradually, in the process of transition from pro- to metaphase accompained by the growth of spindle and asters. The typical growth of contact zone between the blastomeres of the common pond snail embryos was inhibited to a different extent under their cultivation after the 1 cleavage division in the calcium-free media or after trypsinization. At the same time the orientation of meta-anaphase spindles was markedly affected (as judged by an angle alpha between the spindle axis and the plane of contact zone in the equatorial projection). When analyzing the model distributions of the angles between the two spindle axes (in the same projection), it was shown that the empirical distributions of these angles corresponded to the principle of stochastic combination of two alpha. A conclusion is drawn that the orientation of one spindle does not depend on that of another but the position of each of them depends on the size of the contact zone and, hence, on the general form of the adjacent blastomere region. Some other processes determining the spindle orientation are discussed.

Anaphase↗