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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↗
PubMed2002

[Client-orientation versus institutional-orientation. What helps towards client-orientation in psychiatric settings?].

Client- or Patient-Orientation is seen as an indicator for quality of psychiatric work. How to observe and record this orientation? Three different concepts are presented: the German A11, a staff- and client-oriented documentation, Soteria Bern, and Shepherd's 25 homes-investigation around London. Four areas of typical conflicts of interest between client- and institutional orientation are presented with examples: duty times, strategies to fill up beds, "creaming off", and application-talks for clients to enter a residential setting. On the basis of the quality of Life and Care research and the 3 concepts above questions for visiting and evaluating homes and living groups and for personal check-ups are presented.

Conflict of Interest↗
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↗
PubMed2001

Comparison of orientation maps obtained with different number of stimulus orientations.

The structure of orientation maps computed from a different number of stimulus orientations was studied in visual cortical area 18 of the cat. Single condition maps (SCMs) were obtained to 16 stimulus orientations, of which angle maps were generated using 4, 8, and 16 SCMs corresponding to multiples of 45, 22.5, and 11.25 degrees, respectively. The overall orientation distribution of the three types of maps was compared on a pixel-by-pixel basis. Twenty percent of the pixels of the 4-orientations maps differed by more than +/-17 degrees from those produced by 16 orientations. Maps of 8 orientations differed by 6.4 and 5.8% from those of 4 and 16 orientations, respectively. Structural differences between the maps were mainly found at locations displaying high rate of change in orientation preference, i.e., orientation centers and adjoining short, fracture-like zones. These changes included lateral shifts up to 155 microm (average: 38.7 microm) in the position of orientation centers and appearance/disappearance of orientation centers when compared between different conditions. In general, these changes were three times more frequent between maps of 4/8 and 4/16 orientations than 8/16 orientations. It is concluded that orientation maps should be calculated from activity maps representing 8 or more stimulus orientations.

Animals↗
PubMed2004

Symmetric Euler orientation representations for orientational averaging.

A new kind of orientation representation called symmetric Euler orientation representation (SEOR) is presented. It is based on a combination of the conventional Euler orientation representations (Euler angles) and Hamilton's quaternions. The properties of the SEORs concerning orientational averaging are explored and compared to those of averaging schemes that are based on conventional Euler orientation representations. To that aim, the reflectance of a hypothetical polycrystalline material with orthorhombic crystal symmetry was calculated. The calculation was carried out according to the average refractive index theory (ARIT [T.G. Mayerhöfer, Appl. Spectrosc. 56 (2002) 1194]). It is shown that the use of averaging schemes based on conventional Euler orientation representations leads to a dependence of the result from the specific Euler orientation representation that was utilized and from the initial position of the crystal. The latter problem can be overcome partly by the introduction of a weighing factor, but only for two-axes-type Euler orientation representations. In case of a numerical evaluation of the average, a residual difference remains also if a two-axes type Euler orientation representation is used despite of the utilization of a weighing factor. In contrast, this problem does not occur if a symmetric Euler orientation representation is used as a matter of principle, while the result of the averaging for both types of orientation representations converges with increasing number of orientations considered in the numerical evaluation. Additionally, the use of a weighing factor and/or non-equally spaced steps in the numerical evaluation of the average is not necessary. The symmetrical Euler orientation representations are therefore ideally suited for the use in orientational averaging procedures.

Crystallization↗
PubMed2005

Orientation-restricted continuous visual exposure induces marked reorganization of orientation maps in early life.

To elucidate the effect of visual experience on the development of orientation maps, we conducted intrinsic signal optical imaging of the visual cortex of kittens that were continuously exposed to a single orientation through cylindrical-lens-fitted goggles under a freely moving condition starting at post-natal week 3. We observed a rapid reorganization of orientation maps, characterized by extensive representation of exposed orientations with reduced responsiveness to unexposed orientations. The over-representation of exposed orientation was marked for 1-2 weeks of goggle rearing. A longer period of goggle rearing, however, decreased the degree of over-representation, which still remained at a remarkable level. Dark rearing episodes daily interleaved between single orientation exposures moderated the over-representation effect. Unit recording from goggle-reared kittens showed preferred orientations consistent with optical imaging. Using c-Fos immunoreactivity mapping, we showed that the number of neurons strongly responding to the exposed orientation was 3 times larger in a goggle-reared cat than the number of neurons responding to the vertical orientation in a normal cat. Taken together, these results suggest that the reorganization of orientation maps was caused by the expansion of domains maximally responding to exposed orientation as well as the strong reduction of responses to unexposed orientations.

Algorithms↗
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↗
PubMed1981

Restriction of visual experience to a single orientation affects the organization of orientation columns in cat visual cortex. A study with deoxyglucose.

In six dark reared, 4-weak-old kittens visual experience was restricted to contours of a single orientation, horizontal or vertical, using cylindrical lenses. Subsequently, the deoxyglucose method was used to determine whether these artificial raising conditions had affected the development of orientation columns in the visual cortex. After application of the deoxyglucose pulse one hemifield was stimulated with vertical, the other with horizontal contours. Thus, from interhemispheric comparison, changes in columnar systems corresponding to experienced and inexperienced orientations could be determined. The following results were obtained: (1) Irrespective of the restrictions in visual experience, orientation columns develop in areas 17, 18, 19 and in the visual areas of the posterior suprasylvian sulcus. (2) Within area 17, spacing between columns encoding the same orientations is remarkably regular (1 mm), is not influenced by selective experience and shows only slight interindividual variation. (3) In non-striate areas the spacing of columns is less regular and the spatial frequency of the periodicity is lower. (4) The modifiability of this columnar pattern by selective experience is small within the granular layer of striate cortex but substantial in non-granular layers: Within layer IV columns whose preference corresponds to the experienced orientation are wider and more active than those encoding the orthogonal orientation but the columnar grid remains basically unaltered. Outside layer IV the columnar system is maintained only for columns encoding the experienced orientations. The deprived columns by contrast frequently fail to extend into non-granular layers and remain confined to the vicinity of layer IV. (5) These modifications in the columnar arrangement are more pronounced in striate cortex than in nonstriate visual areas and, within the former, more conspicuous in the central than in the peripheral representation of the visual field. It is concluded that within layer IV the blue print for the system of orientation columns is determined by genetic instructions: first order cells in layer IV develop orientation selectivity irrespective of experience whereby the preference for a particular orientation is predetermined by the position in the columnar grid. Dependent on experience is, however, the expansion of the columnar system from layer IV into non-granular layers. It is argued that all distortions following selective rearing can be accounted for by competitive interactions between intracortical pathways, the mechanisms being identical to those established for competitive processes in the domain of ocular dominance columns. It is proposed that such experience dependent modifiability of connections between first and second order cells is a necessary prerequisite for the development of orientation selectivity in cells with large and complex receptive fields.

Animals↗
PubMed2005

The difference in trochlear orientation between the natural knee and current prosthetic knee designs; towards a truly physiological prosthetic groove orientation.

The patella groove of total knee replacements has evolved from a groove with a neutral orientation to a groove with a lateral (also referred to as valgus) orientation. In this study the authors questioned whether femoral components with a lateral groove orientation more closely approximate the configuration in the natural knee. The groove orientations of an implanted CKS femoral component, available in different sizes and with different groove orientations, were determined and compared with formerly published measurements of the natural trochlear orientation. It was found that the prosthetic groove orientations differed considerably from human anatomy, up to a maximum deviation of 6.4 degrees. The orientations of the prosthetic grooves were all equal within the area of the natural trochlea. The area of the natural trochlea guides the patella between about 30 degrees and 120 degrees of knee flexion. The orientations of the prosthetic grooves were different in the area of the supracondylar pouch/proximal anterior flange. This area guides the patella between about 0 degrees and 30 degrees of knee flexion. As this study showed a considerable deviation between natural and prosthetic groove orientation, an optimal prosthetic groove orientation, matching the average orientation in the natural knee, was mathematically determined.

Arthroplasty, Replacement, Knee↗
PubMed1995

Orientation contrast vs orientation in line-target detection.

This study concerns the roles of absolute and relative orientation in determining detectability of a line-element target in a background field of uniformly oriented line elements. Target detectability was determined as a function of background-field orientation, sampled at 5 deg intervals, for three levels of orientation contrast--the difference between target and background orientations--sampled at 10, 20 and 30 deg. Stimulus displays were presented briefly and followed by a mask. There were 10 observers, whose detection performance was quantified by the discrimination index d' from signal detection theory. Target detectability was found to depend both on absolute orientation, represented by background-field orientation, and on orientation contrast. At each level of orientation contrast, performance was best when the background field, not the target element, was vertical or horizontal. These data are difficult to explain by general models of orientation discrimination based on simple orientation opponency between local line-sensitive filter units; three other models specifically concerned with target detection are briefly considered.

Adult↗
PubMed2000

Reality orientation for dementia.

BACKGROUND: Reality Orientation (RO) was first described as a technique to improve the quality of life of confused elderly people, although its origins lie in an attempt to rehabilitate severely disturbed war veterans, not in geriatric work. It operates through the presentation of orientation information (eg time, place and person-related) which is thought to provide the person with a greater understanding of their surroundings, possibly resulting in an improved sense of control and self-esteem. There has been criticism of RO in clinical practice, with some fear that it has been applied in a mechanical fashion and has been insensitive to the needs of the individual. There is also a suggestion that constant relearning of material can actually contribute to mood and self-esteem problems. There is often little consistent application of psychological therapies in dementia services, so a systematic review of the available evidence is important in order to identify the effectiveness of the different therapies. Subsequently, guidelines for their use can be made on a sound evidence base. OBJECTIVES: To assess the evidence of effectiveness for the use of Reality Orientation (RO) as a classroom-based therapy on elderly persons with dementia. SEARCH STRATEGY: Computerised databases were searched independently by 2 reviewers entering the terms 'Reality Orientation, dementia, control, trial or study'. Relevant websites were searched and some handsearching was conducted by the reviewer. Specialists in the field were approached for undocumented material, and all publications found were searched for additional references. SELECTION CRITERIA: All randomised controlled trials (RCTs), and all controlled trials with some degree of concealment, blinding or control for bias (second order evidence) of Reality Orientation as an intervention for dementia were included. The criteria for inclusion/exclusion involved systematic assessment of the quality of study design and the risk of bias, using a standard data extraction form. A measure of cognitive and/or behavioural change was needed. DATA COLLECTION AND ANALYSIS: Data were extracted independently by both reviewers, using a previously tested data extraction form. Authors were contacted for data not provided in the papers. Psychological scales measuring cognitive and behavioural changes were examined. MAIN RESULTS: 6 RCTs were entered in the analysis, with a total of 125 subjects (67 in experimental groups, 58 in control groups). Results were divided into 2 subsections: cognition and behaviour. Change in cognitive and behavioural outcomes showed a significant effect in favour of treatment. REVIEWER'S CONCLUSIONS: There is some evidence that RO has benefits on both cognition and behaviour for dementia sufferers. Further research could examine which features of RO are particularly effective. It is unclear how far the benefits of RO extend after the end of treatment, but and it appears that a continued programme may be needed to sustain potential benefits.

Aged↗
PubMed2006

Orientation selectivity in the common marmoset (Callithrix jacchus): the periodicity of orientation columns in V1 and V2.

Orientation selectivity is a ubiquitous property of the primary visual cortex of mammals. Within the primate, orientation selectivity is arranged into vertical columns that are organized into a regular patchy pattern. Previous studies, in old world primates, have noted an anisotropy in this arrangement that appears to be due to the presence of ocular dominance columns within the same tissue. In addition, orientation selective responses appear to be arranged into bands of activity within the adjoining extrastriate region V2. Little is known about the precise arrangement of orientation columns within V2. In this study, we examined the layout of orientation columns within both V1 and V2 of a new world primate, the common marmoset, using optical imaging. New world primates have the advantage that, unlike the macaque, V2 exists on the cortical surface, a requirement for this form of optical mapping. We found the arrangement of orientation columns to be isotropic within marmoset V1 with an average repeat distance of around 575 mum, smaller than the repeat distance previously reported for the macaque. We found no evidence of ocular dominance within the animals tested supporting the claim that ocular dominance columns when present distort the mapping of orientation in V1. In V2 we found that orientation columns were larger and as in other primates were represented in discrete bands throughout V2. Orientation columns were spaced on average around 1 mm apart. This suggests that, at least in the marmoset, the visual system maps orientation at a different scale within V1 and V2.

Animals↗
PubMed2003

The role of local grouping and global orientation contrast in perception of orientation-modulated textures.

We explored the contribution to perception of orientation-modulated textures of visual processes selective either for orientation contrast or orientation grouping. To distinguish between these two processes we manipulated the axis of local grouping of texture elements independently of the direction of global orientation modulation. The general question posed was whether visibility of texture structure (measured as threshold for discriminating spatial-frequency of texture structure) is dependent on the magnitude of orientation contrast, strength and direction of local grouping, or some combination of the two. We demonstrated that the factor of primary importance is the amplitude of global orientation contrast rather than the presence of local grouping content. Using orientation-interleaved textures (containing two superimposed textures modulated around orthogonal orientations), we further showed that orientation single-opponent processes are a more likely candidate for detecting orientation contrast than double-opponent processes.

Contrast Sensitivity↗
PubMed2005

Orientation selectivity without orientation maps in visual cortex of a highly visual mammal.

In mammalian neocortex, the orderly arrangement of columns of neurons is thought to be a fundamental organizing principle. In primary visual cortex (V1), neurons respond preferentially to bars of a particular orientation, and, in many mammals, these orientation-selective cells are arranged in a semiregular, smoothly varying map across the cortical surface. Curiously, orientation maps have not been found in rodents or lagomorphs. To explore whether this lack of organization in previously studied rodents could be attributable to low visual acuity, poorly differentiated visual brain areas, or small absolute V1 size, we examined V1 organization of a larger, highly visual rodent, the gray squirrel. Using intrinsic signal optical imaging and single-cell recordings, we found no evidence of an orientation map, suggesting that formation of orientation maps depends on mechanisms not found in rodents. We did find robust orientation tuning of single cells, and this tuning was invariant to stimulus contrast. Therefore, it seems unlikely that orientation maps are important for orientation tuning or its contrast invariance in V1. In vertical electrode penetrations, we found little evidence for columnar organization of orientation-selective neurons and little evidence for local anisotropy of orientation preferences. We conclude that an orderly and columnar arrangement of functional response properties is not a universal characteristic of cortical architecture.

Action Potentials↗
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↗
PubMed1996

Magnetically orientated tissue-equivalent tubes: application to a circumferentially orientated media-equivalent.

Circumferential orientation of collagen fibrils in a media-equivalent (ME) is achieved in a simple and effective way using the orientating effects of a strong magnetic field during collagen fibrillogenesis when the ME is first created. Circumferential orientation of the entrapped smooth muscle cells (SMC) is achieved subsequently via cell contact guidance, the induced SMC orientation along orientated fibrils. After describing the methods used, several lines of evidence are provided showing that the magnetically orientated ME is circumferentially orientated, including collagen birefringence, circumferential SMC orientation, accelerated ME compaction and increased ME stiffness with reduced creep in the circumferential direction as compared to control MEs not exposed to a magnetic field during fibrillogenesis. The optimization of these methods is discussed in order to better mimic the circumferential orientation and mechanical properties of a natural medium. Other applications of magnetically orientated tissue-equivalents are indicated.

Animals↗
PubMed2000

Parallel detection of orientation differences in the presence of orientation gradients.

We measured thresholds and reaction times for detecting a target, defined by orientation contrast, as a function of the number of elements displayed simultaneously and of the linear orientation gradient present in the display. This test served to evaluate how well the human visual system is able to ignore smooth gradients in orientation - similar to what it does with gradients of luminance or wavelength. Smooth orientation gradients are common in natural environments as opposed to the usual laboratory (search) experiments. It turns out that targets defined by a discontinuity in the transition between line orientations can be processed in parallel, i. e. that 'search' times increase by between 0.5 and 6 ms, on average, per additional element displayed, irrespective of the number of elements. But thresholds of orientation difference for the detection of the target increase linearly with the orientation gradient present in the display, and tend to increase more strongly for small gradients, indicating a special bonus for (near) collinearity. The averaged data follow a Weber-law type while this is not true for the individual observers' data. These results show that the visual system is indeed able to detect targets based on orientation contrast, rather than on absolute orientation [cf. Nothdurft (1985). Vision Research, 25, 551-560], but that the orientation gradient cannot be ignored.

Computer Graphics↗