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PubMed1993

An orientation-tuned component in the contrast masking of stereopsis.

A masking paradigm was used to evaluate the orientation selectivity of the mechanisms mediating human stereopsis. Two experienced and eleven naive observers viewed stereograms, spatially filtered to contain contrast energy with Gaussian passbands in spatial frequency and orientation. Using forced-choice procedures we measured contrast thresholds for stereopsis in the presence of oriented masking patterns. Our results show that the masking of stereopsis consists of two components: one is orientation dependent, the other is non-oriented and has greatest magnitude at lower spatial frequencies. Contrary to an earlier study, these results imply that stereopsis mechanisms may have similar orientation tuning to mechanisms mediating contrast detection.

Depth Perception↗
PubMed1995

Orientation discrimination in cyclopean vision.

Using a dynamic random-noise display we measured orientation discrimination threshold for two kinds of cyclopean bar and for a cyclopean edge. Ocular vergence was monitored by means of nonious lines. Orientation discrimination threshold for a cyclopean bar or cyclopean edge fell to a minimum at some disparity between about 2 and 50 min arc. For the three subjects tested with bars, the minimum value of discrimination threshold lay between 0.6 and 1.5 deg, and for the two subjects tested with the edge between 0.7 and 2.0 deg. The lowest discrimination thresholds for the cyclopean bars were similar for crossed and uncrossed disparities for all three subjects tested. Matched depth increased smoothly with increasing disparity through a range over which orientation discrimination threshold fell and then levelled out. We conclude that the processing of the depth of a cyclopean form is dissociated from the processing of the orientation of that same cyclopean form. We suggest that orientation discrimination of cyclopean form is determined by the relative activity of binocular, disparity-sensitive, orientation-tuned neurons.

Adult↗
PubMed1993

Production of artificial-orientated mats and strands from plasma fibronectin: a morphological study.

Fibronectin is an extracellular matrix glycoprotein involved in wound healing. Techniques have been developed for the preparation of orientated fibronectin mats from plasma fibronectin, for use in wound healing and tissue repair. Formation of strands and mats is by self-association and aggregation of fibronectin from solution under a directional shear force. Incorporation of heparin with fibronectin modified the mats. Scanning electron microscopy showed that the mats were composed of well-orientated fibrous fibronectin, with a network of internal interconnecting pores. Single strands of fibronectin were prepared for use as a tissue culture model of cell interaction with aggregated orientated fibronectin mats. Rat tail tendon and human skin fibroblasts were used for assessment of cell interaction with both single strands of fibronectin and mats. Fibroblasts rapidly attached to single strands and became orientated. Dense cultures of fibroblasts growing over single strands became orientated, according to the orientation of the underlying fibronectin. Fibroblasts readily grew on the surface of fibronectin mats and were observed within the porous network.

Animals↗
PubMed1988

The development of orientation and direction selectivity in the rabbit visual cortex.

The postnatal development of orientation and direction selectivity of single cells was examined in the primary visual cortex of rabbits. The percentage of cells which were orientation-selective reached adult levels by day 30, whereas the proportion of cells which were direction-selective did not reach adult levels until day 60. Differences in the time course of development of orientation and direction selectivity, together with data previously reported on differences in the effects of deprivation on orientation and direction selectivity, suggest that (1) different mechanisms underly the organization of orientation and direction selectivity and (2) the critical periods for the effects of deprivation on orientation and direction selectivity reflect the different time course of the normal development of these two response properties.

Aging↗
PubMed1992

Orientation and mobility of the heme vinyl groups in myoglobins with the aid of NOE and MATDUHM NMR.

The heme vinyl substituents in a shark (Galeorhinus japonicus) myoglobin in its met-cyano form (MbCN) have been characterized by NMR and the results were compared with those of the well-studied sperm whale (Physter catodon) myoglobin. Their orientation has been inferred from NOE connectivities and the analysis of the hyperfine shifts based on the principal magnetic tensor determined by MATDUHM (Magnetic Anisotropy Tensor Orientation Determination Utilizing the Heme Methyls) [Yamamoto, Y., Nanai, N. and Chujo, R.(1990) J. Chem. Soc., Chem. Commun. 1556-1557]. It has been shown that the C3-vinyl group is oriented roughly orthogonal to the heme plane in both G. japonicus and P. catodon MbCNs at 35 degrees C and their C8-vinyl groups, on the other hand, are close to in-plane orientation. Although CO form of myoglobin (MbCO) and MbCN have been thought to be isostructural to each other, the C8-vinyl orientation for P. catodon MbCN is found to be different from the orthogonal orientation indicated in the crystal structure analysis of MbCO [Hanson, J.C. and Schoenborn, B.P. (1981) J. Mol. Biol. 153, 117-146]. Their mobility has been characterized quantitatively from the study of time-dependent NOE build-up between the selected pair of the vinyl proton resonances. It has been revealed that the heme C3- and C8-vinyl groups of approximately 1 mM G. japonicus MbCN at 45 degrees C undergo internal motion with the correlation time of 1.9 and 2.4 ns, respectively. Therefore, their oscillatory motion is faster by a factor of 4-5 compared with the protein overall tumbling. Difference in the internal mobility between the two vinyl groups in the active site of this Mb is attributed to their differential contact with the apo-protein.

Animals↗
PubMedDate not supplied

Event-related potentials to conjunctions of spatial frequency and orientation as a function of stimulus parameters and response requirements.

ERPs were recorded from subjects who were required to push a button in response to a given conjunction of spatial frequency and orientation (target), and to ignore conjunctions sharing with the target only frequency (frequency-relevant), only orientation (orientation-relevant), or neither (irrelevant). Differences between ERPs to irrelevant and frequency-relevant stimuli were identified as frontal selection positivity (Fz, 150-200 msec post-stimulus), selection negativity (Oz, just after 200 msec), and vertex N2b (200-250 msec). For relevant orientations, the selection negativity and the N2b were also found, but the frontal selection positivity was elicited only when the spatial frequency was relevant as well. Neither of these 3 waves was sensitive to spatial frequency or orientation per se. Other waves (N80, N180) did show such sensitivity, but this was independent of stimulus relevance. Hence, direct evidence for the neural-specificity theory, stating that task-related selective ERP responses reflect differential enhancement of activity in stimulus-specific pathways, was not obtained. It is further concluded that ERPs associated with selection of frequency and orientation are highly comparable to those associated with other visual dimensions (e.g., color), and that selection of multiple visual dimensions may be hierarchical at one level of processing and independent at another.

Adult↗
PubMed1985

Development of oriented dendritic fields in the dorsal cochlear nucleus of the hamster.

The shapes of the apical and basal dendritic fields of the fusiform cells in the dorsal cochlear nucleus of the hamster were analyzed quantitatively. Measurements of the cross-sectional areas of the dendritic fields in planes parallel and perpendicular to planes occupied by the cochlear nerve axons revealed that the apical dendrites have a preferential orientation with respect to the cochlear planes. No consistent orientation of the basal dendrites was apparent. The orientation of the apical dendrites is not present in the neonatal hamster; rather, it develops gradually and is not fully established until after postnatal day 25. Since the cochlear fibers grow into the dorsal cochlear nucleus, establish contacts and become functional before day 25, the presence of the cochlear input might be a prerequisite for the development of oriented dendritic trees. In adult hamsters that have had their cochlear input eliminated during infancy, the apical dendritic trees of the fusiform cells are not oriented normally. The results suggest that the presence of the afferent input is necessary for the differential growth that leads to the development of oriented dendritic trees.

Animals↗
PubMed1995

Measuring substance abuse program treatment orientations: the Drug and Alcohol Program Treatment Inventory.

Assessment of therapeutic orientation is a significant problem in substance abuse program evaluation. This study reports the initial results of a new approach to measuring treatment orientation through a self-report survey that focuses on distinctive features of substance abuse treatment orientations. The Drug and Alcohol Program Treatment Inventory (DAPTI) assesses treatment goals and activities specific to eight orientations: AA/12 Step, Therapeutic Community, Cognitive-Behavioral, Insight/Psychodynamic, Rehabilitation, Dual Diagnosis, Medical and Marital/Family Systems. We present findings from a nationwide assessment of 327 Veterans Administration (VA) Substance Abuse treatment programs that demonstrate promising subscale internal consistency, discriminant validity, and concurrent validity. In addition, the DAPTI distinguishes between programs with independently verified orientations and between inpatient, extended care, outpatient, and methadone maintenance programs. The DAPTI may be helpful in systematically assessing differences in treatment orientations between different types of programs, such as inpatient, community residential, and outpatient care.

Alcoholism↗
PubMed1993

2H NMR lineshapes of immobilized uniaxially oriented membrane proteins.

As a method for the structure determination of integral membrane proteins or other large macromolecular complexes, a solid state 2H NMR approach is presented, capable of measuring the orientations of individual chemical bond vectors. In an immobilized uniaxially oriented sample, the bond angle of a deuterium-labelled methyl group relative to the axis of ordering can be calculated from the quadrupole splitting in the "zero-tilt" spectrum where the sample normal is aligned parallel to the spectrometer field direction. However, since positive and negative values of this splitting cannot be distinguished, there may appear to be two solutions, of which only one describes the correct molecular geometry. We show that it is possible to determine the bond angle uniquely between 0 degree and 90 degrees, by analysing the lineshapes of a tilt series of spectra acquired over different sample inclinations. The lineshape equation describing such oriented 2H NMR spectra will be derived (for asymmetry parameter eta = 0) and discussed, with an illustration of the various linebroadening effects from which the orientational distribution function in the macroscopically ordered system can be determined. This strategy is then applied to specifically deuterium-labelled retinal in dark-adapted bacteriorhodopsin, prepared in a uniaxially oriented sample from purple membrane fragments. From the quadrupole splitting in the zero-tilt spectrum and by lineshape simulations, the deuteromethyl group at C20 on retinal is found to make an angle of 32 degrees +/- 1 degree with the membrane normal, and the sample mosaic spread to be around +/- 8 degrees. The resulting orientation of retinal is in excellent agreement with its known structure in bacteriorhodopsin, and together with the results on other methyl groups it will be possible to construct a detailed picture of the chromophore in the protein binding pocket.

Bacteriorhodopsins↗
PubMed1996

Orientations of helical peptides in membrane bilayers by solid state NMR spectroscopy.

The orientations of helical peptides in membrane bilayers provide important structural information that is directly relevant to their functional roles, both alone and within the context of larger membrane proteins. The orientations can be readily determined with solid state NMR experiments on samples of 15N-labeled peptides in lipid bilayers aligned between glass plates. The observed 15N chemical shift frequencies can be directly interpreted to indicate whether the peptide's helix axis has a trans-membrane or an in-plane orientation. In order to distinguish between these possibilities on the basis of a single spectral parameter, e.g. the easily measured 15N chemical shift frequency, it is necessary to demonstrate that the secondary structure of the peptide is helical, generally by solution NMR spectroscopy of the same peptide in micelle samples, and that it is immobile in bilayers, generally from solid state NMR spectra of unoriented samples. Six different 20-30 residue peptides are shown to have orientations that fall into the categories of trans-membrane or in-plane helices. A model hydrophobic peptide was found to be trans-membrane, several different amphipathic helical peptides were found to have either trans-membrane or in-plane orientations, and a leader or signal peptide, generally regarded as hydrophobic, was found to have a significant population with an in-plane orientation.

Amino Acid Sequence↗
PubMed2006

Regulation of stretch-induced JNK activation by stress fiber orientation.

Cyclic mechanical stretch associated with pulsatile blood pressure can modulate cytoskeletal remodeling and intracellular signaling in vascular endothelial cells. The aim of this study was to evaluate the role of stretch-induced actin stress fiber orientation in intracellular signaling involving the activation of c-jun N-terminal kinase (JNK) in bovine aortic endothelial cells. A stretch device was designed with the capability of applying cyclic uniaxial and equibiaxial stretches to cultured endothelial cells, as well as changing the direction of cyclic uniaxial stretch. In response to 10% cyclic equibiaxial stretch, which did not result in stress fiber orientation, JNK activation was elevated for up to 6 h. In response to 10% cyclic uniaxial stretch, JNK activity was only transiently elevated, followed by a return to basal level as the actin stress fibers became oriented perpendicular to the direction of stretch. After the stress fibers had aligned perpendicularly and the JNK activity had subsided, a 90-degree change in the direction of cyclic uniaxial stretch reactivated JNK, and this activation again subsided as stress fibers became re-oriented perpendicular to the new direction of stretch. Disrupting actin filaments with cytochalasin D blocked the stress fiber orientation in response to cyclic uniaxial stretch and it also caused the uniaxial stretch-induced JNK activation to become sustained. These results suggest that stress fiber orientation perpendicular to the direction of stretch provides a mechanism for both structural and biochemical adaptation to cyclic mechanical stretch.

Animals↗
PubMed2004

Solid-state nuclear magnetic resonance studies of HIV and influenza fusion peptide orientations in membrane bilayers using stacked glass plate samples.

The human immunodeficiency virus (HIV) and influenza virus fusion peptides are approximately 20-residue sequences which catalyze the fusion of viral and host cell membranes. The orientations of these peptides in lipid bilayers have been probed with 15N solid-state nuclear magnetic resonance (NMR) spectroscopy of samples containing membranes oriented between stacked glass plates. Each of the peptides adopts at least two distinct conformations in membranes (predominantly helical or beta strand) and the conformational distribution is determined in part by the membrane headgroup and cholesterol composition. In the helical conformation, the 15N spectra suggest that the influenza peptide adopts an orientation approximately parallel to the membrane surface while the HIV peptide adopts an orientation closer to the membrane bilayer normal. For the beta strand conformation, there appears to be a broader peptide orientational distribution. Overall, the data suggest that the solid-state NMR experiments can test models which correlate peptide orientation with their fusogenic function.

Binding Sites↗
PubMed2006

Toy-oriented changes during early arm movements: hand kinematics.

UNLABELLED: In a recent cross-sectional study, we found that young infants changed their spontaneous arm movements in the presence of a toy, termed 'toy-oriented changes', in systematic ways beginning many weeks before their first consistent reaches [Bhat, A. N., Heathcock, J. H., & Galloway, J. C. (2005). Toy-oriented changes in hand and joint kinematics during the emergence of purposeful reaching. Infant Behavior and Development, 28(4), 445-465]. The purpose of the present study was to test specific hypotheses regarding toy-oriented changes in a longitudinal design. METHODS: Thirteen infants were observed every other week from 8 weeks of age up to the onset of reaching. At each session, hand and joint motions were observed with and without a toy present using a high-speed motion capture system. This paper focuses on the toy-oriented changes in hand variables. RESULTS: As predicted, infants displayed a meaningful pattern of toy-oriented changes, which systematically changed as infants approached the first week of reaching. During the Early phase (8-10 weeks before reaching), infants scaled down their movement length and speed in the presence of a toy. During the Mid phase (4-6 weeks before reaching), infants scaled up movement number and speed, increased movement smoothness, and decreased their hand-toy distance in the presence of a toy. During the Late phase (within 2 weeks of reaching), infants continued to change their hand's position to get closer to the toy and began contacting it. Interestingly, movement number and smoothness displayed similar developmental patterns, where movement length and speed displayed similar patterns. CONCLUSION: Toy-oriented adaptation of arm movements emerges in the first months of life and forms a complex, yet tractable continuum with purposeful reaching. These results provide a foundation to test more specific hypotheses of hand and joint coordination in both typically developing infants and those infants born at risk for coordination impairments.

Age Factors↗
PubMed2004

Measuring sexual orientation in adolescent health surveys: evaluation of eight school-based surveys.

PURPOSE: To examine the performance of various items measuring sexual orientation within 8 school-based adolescent health surveys in the United States and Canada from 1986 through 1999. METHODS: Analyses examined nonresponse and unsure responses to sexual orientation items compared with other survey items, demographic differences in responses, tests for response set bias, and congruence of responses to multiple orientation items; analytical methods included frequencies, contingency tables with Chi-square, and ANOVA with least significant differences (LSD)post hoc tests; all analyses were conducted separately by gender. RESULTS: In all surveys, nonresponse rates for orientation questions were similar to other sexual questions, but not higher; younger students, immigrants, and students with learning disabilities were more likely to skip items or select "unsure." Sexual behavior items had the lowest nonresponse, but fewer than half of all students reported sexual behavior, limiting its usefulness for indicating orientation. Item placement in the survey, wording, and response set bias all appeared to influence nonresponse and unsure rates. CONCLUSIONS: Specific recommendations include standardizing wording across future surveys, and pilot testing items with diverse ages and ethnic groups of teens before use. All three dimensions of orientation should be assessed where possible; when limited to single items, sexual attraction may be the best choice. Specific wording suggestions are offered for future surveys.

Adolescent↗
PubMed2006

Influence of 4-cyano-4'-biphenylcarboxylic acid on the orientational ordering of cyanobiphenyl liquid crystals at chemically functionalized surfaces.

We report two methods that involve tailoring of the chemical composition of the nematic liquid crystal 4-cyano-4'-pentylbiphenyl to achieve control over the orientational ordering of the liquid crystal on chemically functionalized surfaces. The first method involves the direct addition of 4-cyano-4'-biphenylcarboxylic acid to 4-cyano-4'-pentylbiphenyl. The second method involves exposure of 4-cyano-4'-pentylbiphenyl to ultraviolet light and photochemical generation of a range of products, including 4-cyano-4'-biphenylcarboxylic acid. The addition of the acid or exposure to ultraviolet light accelerated the rate at which the liquid crystal exhibited an orientational transition from planar to perpendicular (homeotropic) alignment on surfaces presenting ammonium groups. The appearance of the homeotropic orientation of the UV-treated 4-cyano-4'-pentylbiphenyl on ammonium-terminated surfaces was dependent on the thickness of the film of liquid crystal (13-50 mum), consistent with a dipolar coupling between the liquid crystal and the electric field associated with an electrical double layer generated at the ammonium surface. Although the addition of 4-cyano-4'-biphenylcarboxylic acid or UV treatment of the liquid crystal also promoted homeotropic orientations on surfaces presenting hydroxyl groups, the orientations of the UV-treated liquid crystal on the hydroxyl-terminated surface did not change with thickness of the film of liquid crystal in the manner observed on the ammonium-terminated surfaces. The latter result indicates that the mechanism leading to homeotropic anchoring on hydroxyl-terminated surfaces is distinct from that on ammonium-terminated surfaces. Measurements performed using polarization modulation infrared reflection-absorption spectroscopy suggest that hydrogen bonding between the 4-cyano-4'-biphenylcarboxylic acid and the hydroxyl-terminated surface is responsible for the homeotropic anchoring on the surface. Finally, the orientation of the liquid crystal on methyl-terminated surfaces was not influenced by the addition of 4-cyano-4'-biphenylcarboxylic acid nor UV treatment. These results illustrate how the chemical composition of liquid crystals can be manipulated to achieve control over their ordering on surfaces that possess chemical functionality relevant to the development of liquid crystal-based sensors and diagnostic tools. We illustrate the utility of this approach by using the tailored liquid crystal to amplify and optically transduce the presence of proteins arrayed on ammonium-terminated surfaces.

Biphenyl Compounds↗
PubMed2004

Positive life orientation as a predictor of 10-year outcome in an aged population.

OBJECTIVE: It is well known that depression predicts mortality in old age. However, little is known about the impact of positive emotions. We investigated the impact of positive life orientation on mortality and permanent institutional care in aged birth cohorts. STUDY DESIGN AND SETTING: Participants (born 1904, 1909, and 1914) underwent detailed assessments with follow-up at 5 and at 10 years. Positive life orientation was determined as answering "yes" to all the following items: being satisfied with life, having zest for life, having plans for the future, feeling needed, seldom feeling lonely or depressed. RESULTS: Of participants, 102 (20.8%) had a positive life orientation. After 10 years, 54.5% of them were alive, whereas in the rest of the sample 39.5% survived (P=.004). After controlling for age, gender, and health measures, the impact of positive life orientation was still significant (HR=0.89, 95% CI 0.83-0.93). At 5 years, only 2.9% of those having a positive life orientation but 17.5% of the rest of the sample were in permanent institutional care (P=0.003), with a positive life orientation remaining a significant protector against institutional care (OR 0.58, 95% CI 0.36-0.93). CONCLUSION: Positive attitudes have a long-standing impact on prognosis in old age.

Aged↗
PubMed2006

The effect of ultrasound probe orientation on muscle architecture measurement.

The purpose of this paper was to examine how muscle architecture parameter (MAP) measurements made using brightness-mode ultrasonography (BMU) differ based on probe orientation. The human tibialis anterior muscle was imaged from nine different probe orientations during concentric contractions at four joint angles to determine the effect of probe orientation on the measurement of muscle architecture parameters. Ankle dorsi-flexion torque, tibialis anterior electromyography (EMG), and measures of MAP including fascicle length (FL), pennation angle (PA) and muscle thickness (MT) were collected. Statistically significant differences were found between joint angles for measures of FL and PA and between probe orientations for measures of FL and MT. A comparison of actual MAP values to a geometric model used by researchers to determine an ideal probe orientation show that the actual values vary to a greater extent and do not follow the trend predicted by the model. The results suggest that ultrasound probe orientation affects measures of MAP but the effect either cannot be predicted from a geometric model and/or the error in the measurement technique does not allow a comparison.

Adult↗
PubMed2004

The N-terminal alpha-helix of pancreatic phospholipase A2 determines productive-mode orientation of the enzyme at the membrane surface.

Phospholipase A(2) (PLA(2)) hydrolyzes glycerophospholipids to free fatty acid and lyso-phospholipid, which serve as precursors for the biosynthesis of eicosanoids and other lipid-derived mediators of inflammation and allergy. PLA(2) activity strongly increases upon binding to the surface of aggregated phospholipid. The N-terminal approximately ten residue alpha-helix of certain PLA(2) isoforms plays important roles in the interfacial activation of the enzyme by providing residues for membrane binding of PLA(2) and by contributing to the formation of the substrate-binding pocket. However, the relative contributions of the N-terminal alpha-helix and the rest of the protein in membrane binding of PLA(2) and its productive-mode orientation at the membrane surface are not well understood. Here we use a variety of biophysical approaches to determine the role of the N-terminal helix in membrane binding strength, orientation, and activity of human pancreatic PLA(2). While the full-length PLA(2) binds to membranes with a defined orientation, an engineered PLA(2) fragment DeltaN10 that lacks the N-terminal ten residues binds to membranes with weaker affinity and at random orientation, and exhibits approximately 100-fold lower enzymatic activity compared to the full-length PLA(2), indicating the key role of the N terminus in PLA(2) function. The results of polarized infrared spectroscopic experiments permit determination of the orientation of membrane-bound PLA(2) and identification of its interfacial binding surface. Moreover, the full-length PLA(2) demonstrates increased conformational flexibility in solution and is stabilized upon membrane binding, while the DeltaN10 fragment is more rigid than the full-length PLA(2) both in free and membrane-bound states. Our results suggest that the N-terminal alpha-helix supports the activation of PLA(2) by (a) enhancing the membrane binding strength, (b) facilitating a productive-mode orientation of PLA(2) at the membrane surface, and (c) conferring conformational integrity and plasticity to the enzyme.

Binding Sites↗