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At least 127 records · Page 7Linked to original sources
PubMed1996

Oriented 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine/ganglioside membranes: a Fourier transform infrared attenuated total reflection spectroscopic study. Band assignments; orientational, hydrational, and phase behavior; and effects of Ca2+ binding.

Fourier transform infrared (FTIR) attenuated total reflection (ATR) spectroscopy was used to elucidate the hydration behavior and molecular order of phospholipid/ganglioside bilayers. We examined dry and hydrated films of the gangliosides GM1, deacetyl-GM1, lyso-GM1, deacetyllyso-GM1, and GM3 and oriented mixed films of these gangliosides with 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) using polarized light. Analysis of the amide I frequencies reveals that the amide groups are involved in intermolecular interactions via hydrogen bonds of varying strengths. The tilt angle of the acyl chains of the lipids in mixed films was determined as a function of ganglioside structure. Deacetylation of the sialic acid in the headgroup has a stronger influence on the tilt angle than the removal of the ganglioside fatty acid. The phase behavior was examined by FTIR ATR spectroscopy and by differential scanning calorimetry (DSC) measurements on lipid suspensions. At the same molar concentration, lyso-gangliosides have less effect on changes of transition temperature compared to the double-chain analogs. Distinct differences in the amide band shapes were observed between mixtures with lyso-gangliosides and normal double-chain gangliosides. Determined from the dicroic ratio RATR, the orientation of the COO- group in all DMPC/ganglioside mixtures was found to be relatively fixed with respect to the membrane normal. In 4:1 mixtures of DMPC with GM1 and deacetyl-GM1, the binding of Ca2+ leads to a slight decrease in chain tilt in the gel phase, probably caused by a dehydration of the membrane-water interface. In mixtures of DMPC with GM3 and deacetyl-lyso-GM1, a slight increase in chain tilt is observed. The chain tilt in DMPC/lyso-GM1 mixtures is unchanged. Analysis of the COO- band reveals that Ca2+ does not bind to the carboxylate group of the sialic acid of GM1 and deacetyl-GM1, the mixtures in which a decrease in chain tilt was observed. Binding to the sialic acid was only observed for mixtures of DMPC with GM3, lyso-GM1, and deacetyl-lyso-GM1. Ca2+ obviously accumulates at the bilayer-water interface and leads to partial dehydration of the headgroup region in the gel as well as in the liquid-crystalline phase. This can be concluded from the changes in the amide I band shapes. With the exception of DMPC/deacetyl-GM1, the effects on the ester C==O bands are small. The addition of Ca2+ has minor effects on the phase behavior, with the exception of the DMPC/GM1 mixture.

Animals↗
PubMed1998

Magnitudes and mutual orientations of dipolar and shielding interaction tensors determined from the orientation dependence of spinning sidebands of slowly rotating powder samples.

It is shown that the orientation dependence of spinning sidebands of slowly rotating solids can be exploited to determine with good precision the heteronuclear bond distances and mutual orientation of dipolar and shielding tensors from a single dipolar modulated chemical shift anisotropy spectrum. The method is based on the dynamics of polarization transfer in the initial period of tens of microseconds, and may be useful in solids with relatively isolated groups of spins.

Anisotropy↗
PubMed1994

Memory in naturalistic and laboratory contexts: distinguishing the accuracy-oriented and quantity-oriented approaches to memory assessment.

A distinction is drawn between the quantity-oriented approach to memory that has dominated traditional laboratory research, and the accuracy-oriented approach that is emerging in the study of everyday memory. This distinction is shown to underlie some troubling confusions in the interpretation of empirical findings. In particular, the recall-recognition paradox, which involves the claimed superiority of recall over recognition memory in naturalistic settings, is shown to stem from the common confounding between memory property (quantity vs. accuracy) and 2 other variables that have not generally been distinguished--test format (production vs. selection) and report option (free vs. forced reporting). Three laboratory experiments reveal the fundamentally different roles played by report option and test format in accuracy-based and quantity-based memory research. Implications for memory assessment, metamemory, and the everyday-laboratory controversy are discussed.

Female↗
PubMed2004

Extended rotational diffusion and orientational relaxation of symmetric top molecules in a strong dc electric field: second-rank orientational correlation functions.

Second-rank orientational correlation functions (pertaining to Kerr effect relaxation and Raman scattering) are obtained using the extended rotational diffusion (J-diffusion) model of symmetric top polar molecules in a strong constant external field. It is shown that the shape of the molecule noticeably affects all second-rank correlation functions and relaxation times in the rare collision limit. In the opposite limit of frequent collisions, the quantities of interest are shown to be shape independent as a consequence of vanishingly small inertial effects. An interpolation formula for the orientation relaxation times in the intermediate regime between the rare and frequent collision limits is also given.

Journal Article↗
PubMed1982

Orientation of cohesive end site cos determines the active orientation of chi sequence in stimulating recA . recBC-mediated recombination in phage lambda lytic infections.

Sequence chi, 5'G-C-T-G-G-T-G-G, locally enhances homologous recombination by recA and recBC proteins of Escherichia coli. Previous work showed that, in phage lambda, chi is more active in one orientation (leftward) than in the other (rightward). Inverting cos, the sequence for the mature DNA ends of lambda, reverses this orientation dependence: the rightward chi becomes fully active, and the leftward chi becomes relatively inactive. We surmise that chi action in phage lambda is coupled with DNA packaging or injection.

Bacterial Proteins↗
PubMed1998

The influence of sensor orientation on activity-based rate responsive pacing. Sensor Orientation Study Group.

Piezoelectric activity-based rate responsive pacemakers are commonly implanted with the sensor facing inward. This study was conducted to assess the safe and effective rate response of an activity-based rate responsive pacemaker implanted with the sensor facing outward. A comparison were made to a previously studied patient group with sensor facing inward. Patient and pacemaker data was collected at predischarge and 2-month follow-up. Two-minute hall walks in conjunction with programmer-assisted rate response assessment were utilized to standardize initial rate response parameter settings for both patient groups. At 2-month follow-up, sensor rate response to a stage 3 limited CAEP protocol was recorded. Adequate sensor rate response was achieved for both patient groups. No difference was noted in reported patient complications for both groups. A statistically significant difference in programmed rate response curve setting and activity threshold for the two groups was noted at 2-month follow-up. Adequate sensor rate response was achieved for a patient population implanted with an activity-based rate responsive pacemaker with sensor facing outward. In this orientation, one higher rate response curve setting and an activity threshold one value more sensitive were required on average when compared to the normal sensor orientation group.

Aged↗
PubMed1997

Deconstructing sexual orientation: understanding the phenomena of sexual orientation.

The very terms of a debate about whether or not sexual orientation is primarily a biological phenomenon fail to consider the complex origins of the phenomenon. Deconstruction of the term "homosexuality" shows that it refers to multiple factors which cannot be studied as or subsumed under a unitary concept. Adequate understanding of sexual orientation must consider the developmental, interpersonal, experiential, and cultural dimensions of sexuality, as well as any biological contributions to sexual attraction, behavior, and identity.

Female↗
PubMed2001

A randomized controlled trial of community-oriented and hospital-oriented care for discharged psychiatric patients: influence of personality disorder on police contacts.

An important forensic psychiatric measure, contacts with police, was compared in a randomized, controlled trial of 155 patients with severe mental illness with a previous admission within the past two years. The patients, who also had their personality status addressed formally before randomization, were allocated to community multidisciplinary teams or to hospital-based care programs after discharge from in-patient care and were followed up for one year. A total of 138 patients (89%) had at least one post-baseline assessment and of these patients, 16 (12%) had at least one police contact in the year of the study, most of which were emergency assessments. The data showed significantly greater numbers of police contacts in patients with increasing severity of personality disturbance. Patients with such disturbance were six times more likely to have police contacts than those with no personality disorder. There were significantly more contacts in patients with borderline and antisocial (dissocial) personality disorder allocated to community-oriented care compared with hospital-oriented care. These findings have important implications for risk assessment in severe mental illness.

Adolescent↗
PubMed2004

Orientation and pore-forming mechanism of a scorpion pore-forming peptide bound to magnetically oriented lipid bilayers.

The orientation and pore-forming mechanisms of pandinin 2 (pin2), an antimicrobial peptide isolated from venom of the African scorpion Pandinus imperator, bound to magnetically oriented lipid bilayers were examined by 31P and 13C solid-state, and 15N liquid-state NMR spectroscopy. 31P NMR measurements at various temperatures, under neutral and acidic conditions, showed that membrane lysis occurred only under acidic conditions, and at temperatures below the liquid crystal-gel phase transition of the lipid bilayers, after incubation for two days in the magnet. Differential scanning calorimetry measurements showed that pin2 induced negative curvature strain in lipid bilayers. The 13C chemical shift values of synthetic pin2 labeled at Gly3, Gly8, Leu12, Phe17, or Ser18 under static or slow magic-angle spinning conditions, indicate that pin2 penetrates the membrane with its average helical axis perpendicular to the membrane surface. Furthermore, amide H-D exchange experiments of 15N-Ala4, Gly8, and Ala9 triply-labeled pin2 suggest that this peptide forms oligomers and confirms that the N-terminal region creates membrane pores.

Binding Sites↗
PubMed1998

Concept-oriented standardization and statistics-oriented classification: continuing the classification versus nomenclature controversy.

Nowadays, most activities on controlled medical vocabularies focus on the provision of a sufficient atomic-level granularity for representing clinical data. Amongst others, clinical vocabularies should be concept oriented, compositional and should also reject "Not Elsewhere Classified". We strongly share the opinion that there is a need to deal with serious deficits of existing manually created vocabularies and with new demands for computer-based advanced processing and exchange of medical language data. However, we do not share the opinion that methodological requirements like observational and structural comparability needed for sound statistics should not be included in desiderata of controlled medical vocabularies. Statistical-oriented classifications are not developed for representing detailed clinical data but for providing purpose-dependent classes where cases of interest are assigned uniquely. Either statistical classifications are not included into the set of controlled medical vocabularies in the sense of Cimino, or his desiderata are misleading. We argue that statistical classifications should be linked to (formal) concept systems, but again this linkage does not change their different natures. With this article we continue the "classification versus nomenclature" controversy referring to Coté.

Data Interpretation, Statistical↗
PubMed1991

Orientation in birds. Spatiotemporal programmes and genetics of orientation.

A number of migratory bird species have endogenous annual rhythms that regulate the entire annual cycle, including migration. Moreover, captive migrants display inherited migrational activity; this could theoretically also be used by free-living migrants as a time programme for migration. Finally, this heritable migrational activity is oriented in a seasonally appropriate direction, even in naive birds. These characteristics should enable inexperienced migrants isolated from contact with experienced conspecifics, to utilize a heritable vector-navigation programme to migrate from the breeding grounds to the winter quarters. That is, migrants should reach goal areas they have never experienced by migrating in programmed directions, for as long a period as the genetically fixed time programme for migrational activity induces them to do so. The time course of migration, as established by trapping stations, theoretical influences of environmental variables on migration programmes, and also compensatory behaviour and backup measures, are discussed. The present evidence supports the view that a large number of migrants are essentially brought to their wintering areas by vector-navigation systems.

Animals↗
PubMed2002

The influence of selective lesions to components of the hippocampal system on the orienting [correction of orientating] response, habituation and latent inhibition.

The contribution that components of the hippocampal system in the rat make to the modulation of attention or stimulus processing was assessed using several simple behavioural assays: the orienting response (OR) to a novel stimulus, the subsequent habituation and dishabituation of this OR, and the latent inhibition effect that typically results from repeated exposure to a stimulus. Excitotoxic lesions of components of the hippocampal system produce dissociable effects on the OR, habituation and latent inhibition: lesions of the entorhinal cortex have no effect on the OR or changes in the OR during exposure to a stimulus, but disrupt latent inhibition; lesions of the subiculum disrupt the OR but not latent inhibition; and lesions of the hippocampus disrupt the OR and latent inhibition. These effects have important implications for our understanding of habituation and latent inhibition, and the neural mechanisms involved in attentional modulation.

Animals↗
PubMed1995

Stimulus-response compatibility for vertically oriented stimuli and horizontally oriented responses: evidence for spatial coding.

It has previously been shown that, when stimuli positioned above or below a central fixation point ("up" and "down" stimuli) are assigned to left and right responses, the stimulus-response mapping up-left/down-right is more compatible than the mapping up-right/down-left for responses executed by the left hand in the left hemispace, but this relation is reversed for responses executed by the right hand in the right hemispace. In Experiment 1, each hand responded at locations in both hemispaces to dissociate the influence of hand identity from response location, and response location was found to be the determinant of relative compatibility. In Experiment 2 responses were made at the sagittal midline, and an inactive response switch was placed to the left or right to induce coding of the active switch as right or left, respectively. This manipulation of relative location had an effect similar to, although of lesser magnitude than, that produced by physically changing location of the response switch in Experiment 1. It is argued that these results are counter to predictions of a movement-preference account and consistent with the view that spatial coding underlies compatibility effects for orthogonally oriented stimulus and response sets.

Adult↗
PubMed2000

Partial orientation pop-out helps difficult search for orientation.

We interrupted pop-out search before it produced a detection response by adding extra distractors to the search display. We show that when pop-out for an orientation target fails because of this interruption, it nevertheless provides useful information to the processes responsible for difficult search. That is, partial pop-out assists difficult search. This interaction has also been found for color stimuli (Olds, Cowan, & Jolicoeur, 2000a, 2000b). These results indicate that interactions and/or overlap between the mechanisms responsible for pop-out and the mechanisms responsible for difficult search may be quite general in early visual selection.

Adult↗
PubMed1975

[Orientation without external orientation clues in reptiles (Hemidactylus frenatus Gekkonidae)].

In a black-painted cylindric arena Geckos (Hemidactylus frenatus) are able to find their hiding place without the aid of external orientation clues. This proprioceptive knowledge of the position is independent of the azimuth of the actual position of head and body, but it is influenced by a passive turning of the reptile. These findings lead to the assumption that the receptors of the labyrinth participate in the endogeneous (idiothetic) course control.

Animals↗
PubMed1979

The influence of verbal descriptions versus orientation codes on kindergartners' memory for the orientation of pictures.

Kindergarten children who viewed a series of 10 line drawings of objects subsequently showed little ability to distinguish between these pictures and their left-right mirror images. However, the children's memory for orientation improved substantially when children were induced to (a) give detailed verbal descriptions of the pictures, or (b) specify a difference between characteristics on the child's side versus the experimenter's side of each picture, or (c) both. The 3 induced strategies were equally effective. On a posttest given approximately a week later, the children did not maintain use of any of these effective strategies.

Attention↗
PubMed1998

Impaired stimulus-driven orienting of attention and preserved goal-directed orienting of attention in unilateral visual neglect.

Neglect patients do not respond to stimuli presented on the side of space contralateral to the side of their brain lesions, indicating deficits to attentional or representational mechanisms. We describe a patient who shows a left neglect in normal reading and line bisection but an intact ability to locate the left end of the stimulus. Further tests showed that his seemingly intact ability to search into the "neglected" side was due to his ability to use local elements of the stimulus as cues in his serial search for the left end. The patient's left neglect was significantly reduced after he located the left end of the stimulus. In contrast, his neglect was not reduced by making the stimulus on the neglected side physically more salient. These results suggest that his neglect is due largely to an impairment of the mechanism mediating automatic, stimulus-driven orienting of attention. In contrast, the controlled goal-directed attentional search is largely preserved and can be used to alleviate neglect.

Apraxias↗
PubMed1992

Tangible differences between adolescent-oriented and adult-oriented prenatal care.

Comprehensive prenatal care reduces many of the risks associated with adolescent childbearing. To learn why this intervention strategy is successful, we compared the care received by 123 poor, black, younger than 19-year-olds in an adolescent-oriented prenatal program to that received by 72 sociodemographically similar, black, 19-30-year-olds in a university hospital-based prenatal clinic. We found that adolescents entered care later (13.6 +/- 5.6 vs. 11.7 +/- 3.4 weeks; p less than 0.01) and were less likely to obtain an adequate quantity of care then were adults (45.5% vs. 61.1%; p = 0.04). However, teens were enrolled in the Women, Infant, and Children (WIC) food supplement program more rapidly than adults (within 7 +/- 6 vs. 10 +/- 6 weeks of the first prenatal visit; p = 0.002), were referred more often to community service agencies for help with nonobstetric, psychosocial, and financial problems (37.4% vs. 18.3%; p less than 0.0001), and were tested and treated more frequently for sexually transmitted diseases (p less than 0.0001). When the adolescents entered care they were smaller, had lower hematocrits, more social and behavioral problems, poorer diets, and more sexually transmitted diseases than did the adults. Later in gestation, however, hematocrits, diets, weight gain, and birth outcomes were similar in the two groups. The implications of these findings for health care providers and for further research are discussed.

Adolescent↗