Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “patterning”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
PubMedDate not supplied

[Serum immunoglobulin patterns in rheumatoid arthritis].

Immunoglobulins were estimated quantitatively in sera from patients with rheumatoid arthritis. According to the significantly increased immunoglobulin class(es), in RA patients as compared to normals the following immunoglobulin patterns were registered: IgG pattern, IgM pattern, IgA pattern, IgG-IgM-IgA pattern, IgG-IgM pattern and IgG-IgA pattern. The IgG-, IgA- and IgG-IgM-IgA patterns were predominantly found in sera from patients with seropositive RA. A positive correlation was found between other inflammatory parameters and high titered rheumatoid factor of the IgG-IgM-IgA-, IgG-IgA- and IgM patterns. C-reactive proteins were increased more frequently in seropositive cases and correlated quantitatively with the IgG-IgA-, IgG-IgM-, IgG-IgM-IgA and IgA patterns. Maximal erythrocyte sedimentation rates were accompanied with the IgG-IgA-, IgG-IgM-IgA- and IgG-IgM pattern. The serum complement components C 3 and C 4 were not decreased in neither seropositive nor seronegative RA. The formation of antiglobulins in hypergammaglobulinemic patients with RA induced by an increased immunoglobulin catabolism is suggested as a possible pathogenetic mechanism.

Arthritis, Rheumatoid↗
PubMed1996

[Classification of patterns of nocturnal penile tumescence with continuous monitoring of penile rigidity: analysis of various factors affecting erection].

In 43 men who required further examination of erectile function, we analyzed the relationship between the various factors including hormone levels, penile blood pressure index (PBPI), shape of the arterial wave, erection period after prostaglandin E1 injection and dynamic cavernosography/metry, as well as the patterns of nocturnal penile tumescence (NPT) with rigidity. Normal, dissociation, short episode, low amplitude and flat trace patterns, which were classified by Kaneko, were observed in 11, 8, 11, 2 and 11 men, respectively. Uncoupling was not observed in any men. There were no differences in the levels of prolactin and LH among the 6 patterns. A high FSH level was seen in men with a flat trace pattern; a low level of free testosterone ( < 12.2 pg/ml) was seen in men with dissociation, low amplitude and flat trace patterns, and low PBPI ( < 0.75) in men with flat trace pattern; and an arteriosclerotic shape of the arterial wave was seen in men with short episode and flat trace patterns. Each erection period immediately after prostaglandin E1 injection in men with dissociation, short episode, low amplitude and flat trace was shorter compared with cases with a normal pattern. Venoocclusive dysfunction was observed in 5 men with a dissociation pattern and 6 men with a flat trace pattern. In conclusion, an integral analysis of pattern of NPT with rigidity and other examinations are useful for differentiating organic impotence from psychogenic impotence and for accurately diagnosing pathophysiological disorders of organic impotence and underlying diseases.

Adult↗
PubMed1996

In vitro biomechanical comparison of the strength of the linea alba of the llama, using two suture patterns.

OBJECTIVE: To compare the strength of the sutured linea alba, in vitro, using 2 suture patterns. ANIMALS: 12 clinically normal llamas. PROCEDURE: 2 incisions in the linea alba of 12 llamas were closed with a simple continuous or inverted cruciate pattern, and tissue was harvested after 10 days. In 6 llamas the simple continuous line was intact; the inverted cruciate specimens contained 6 sutures. In 6 llamas, 1 knot was excised in the simple continuous pattern to simulate a failed line; the cruciate pattern contained 5 knots. Tissue sections were taken from cranial, between, and caudal to the linea alba incisions to compare fascial thickness. The sutured specimens were mounted in a mechanical testing system and tested to failure. A mixed-model ANOVA was used to evaluate the effects of suture pattern and incisional position on mechanical properties. RESULTS: Significant differences were not found between suture patterns or between location for yield force, failure force, or yield strain, whereas failure strain was lower for the intact simple continuous pattern than the inverted cruciate pattern (P = 0.003). From histomorphometric analysis, the caudal tissue specimens were significantly thinner than the middle tissue specimen cranial to the umbilicus (P = 0.006). CONCLUSION: There was no significant difference in monotonic breaking strength of the linea alba sutured with the simple continuous or inverted cruciate pattern. CLINICAL RELEVANCE: These results justify the use of the simple continuous pattern over the cruciate pattern for ventral midline closure in llamas because of the ease of placement and speed.

Abdominal Muscles↗
PubMed2000

Mathematical modelling of juxtacrine patterning.

Spatial pattern formation is one of the key issues in developmental biology. Some patterns arising in early development have a very small spatial scale and a natural explanation is that they arise by direct cell-cell signalling in epithelia. This necessitates the use of a spatially discrete model, in contrast to the continuum-based approach of the widely studied Turing and mechanochemical models. In this work, we consider the pattern-forming potential of a model for juxtacrine communication, in which signalling molecules anchored in the cell membrane bind to and activate receptors on the surface of immediately neighbouring cells. The key assumption is that ligand and receptor production are both up-regulated by binding. By linear analysis, we show that conditions for pattern formation are dependent on the feedback functions of the model. We investigate the form of the pattern: specifically, we look at how the range of unstable wavenumbers varies with the parameter regime and find an estimate for the wavenumber associated with the fastest growing mode. A previous juxtacrine model for Delta-Notch signalling studied by Collier et al. (1996, J. Theor. Biol. 183, 429-446) only gives rise to patterning with a length scale of one or two cells, consistent with the fine-grained patterns seen in a number of developmental processes. However, there is evidence of longer range patterns in early development of the fruit fly Drosophila. The analysis we carry out predicts that patterns longer than one or two cell lengths are possible with our positive feedback mechanism, and numerical simulations confirm this. Our work shows that juxtacrine signalling provides a novel and robust mechanism for the generation of spatial patterns.

Animals↗
PubMed2000

Mutational analysis of endothelin receptor b1 (rose) during neural crest and pigment pattern development in the zebrafish Danio rerio.

Pigment patterns of fishes are a tractable system for studying the genetic and cellular bases for postembryonic phenotypes. In the zebrafish Danio rerio, neural crest-derived pigment cells generate different pigment patterns during different phases of the life cycle. Whereas early larvae exhibit simple stripes of melanocytes and silver iridophores in a background of yellow xanthophores, this pigment pattern is transformed at metamorphosis into that of the adult, comprising a series of dark melanocyte and iridophore stripes, alternating with light stripes of iridophores and xanthophores. Although several genes have been identified in D. rerio that contribute to the development of both early larval and adult pigment patterns, comparatively little is known about genes that are essential for pattern formation during just one or the other life cycle phase. In this study, we identify the gene responsible for the rose mutant phenotype in D. rerio. rose mutants have wild-type early larval pigment patterns, but fail to develop normal numbers of melanocytes and iridophores during pigment pattern metamorphosis and exhibit a disrupted pattern of these cells. We show that rose corresponds to endothelin receptor b1 (ednrb1), an orthologue of amniote Ednrb genes that have long been studied for their roles in neural crest and pigment cell development. Furthermore, we demonstrate that D. rerio ednrb1 is expressed both during pigment pattern metamorphosis and during embryogenesis, and cells of melanocyte, iridophore, and xanthophore lineages all express this gene. These analyses suggest a phylogenetic conservation of roles for Ednrb signaling in the development of amniote and teleost pigment cell precursors. As murine Ednrb is essential for the development of all neural crest derived melanocytes, and D. rerio ednrb1 is required only by a subset of adult melanocytes and iridophores, these analyses also reveal variation among vertebrates in the cellular requirements for Ednrb signaling, and suggest alternative models for the cellular and genetic bases of pigment pattern metamorphosis in D. rerio.

Animals↗
PubMed1997

Neural induction and antero-posterior patterning in the amphibian embryo: past, present and future.

Neural induction and patterning in competent ectoderm occurs during gastrula and early neurula stages in response to signals from dorsal mesoderm. The earliest views of antero-posterior (A-P) patterning were modified beginning in the 1930s, as complexities concerning the timing of the pattern-forming process and potential sources of the patterning signals were revealed. In the 1950s and 1960s several different models for A-P patterning were proposed, all of which, however, bear a number of similarities, including a two-component system for generating A-P axial information in the embryo. Early attempts to identify neural-inducing molecules were largely unsuccessful due to technical limitations in biochemical analyses and concerns about assaying neural responses. The advent of modern molecular genetic technology has permitted more precise tests of a number of classic observations about the timing of A-P patterning and the sources of patterning signals. While some early observations have been confirmed, a number of new concepts have emerged in recent years, particularly concerning the source of patterning signals in the embryo. Striking progress has been made in identifying putative neural-inducing molecules, and recent experiments have begun to suggest how these might contribute to A-P patterning. While the successes in recent years have been revealing, many of the classic issues concerning neural induction and patterning remain essentially as they were when first defined many decades ago. The power of modern molecular genetics, however, should permit many of these issues to be significantly clarified in the decades to come.

Amphibians↗
PubMed1984

Subdurally recorded pattern and luminance EPs in the alert rhesus monkey.

Two rhesus monkeys (Macaca mulatta) were trained to fixate a TV screen on which checkerboard and bar patterns could be presented. Stainless steel skull electrodes and electrode bundles under the dura, each containing 7 leads permitting 7 recording sites at 5 mm intervals, were placed over the temporal-occipital cortex and used to obtain visually evoked potentials (VEPs). The following conclusions were reached: VEPs recorded with skull electrodes resemble scalp recorded VEPs. Subdural electrodes may yield larger VEP amplitudes than skull or scalp electrodes. Subdural VEPs vary more in shape with recording site than scalp or skull recorded VEPs. Apart from differences in shape there are topographical differences between luminance and pattern EPs; the luminance EP is localized near the occiput and the pattern EP is most pronounced at the temporal site overlying the foveal projection area. For a given recording site it can be seen that: (a) the amplitude of the pattern reversal EP is smaller than that of the pattern onset EP; (b) the shape of the reversal EP resembles the pattern offset EP; and (c) the shape of the pattern onset EP is rather invariant to check size and bar width. On the basis of the pattern EP the striate and prestriate cortical areas can be distinguished as follows: (a) the prestriate cortex yields a positive-negative-positive (PNP) response complex to pattern onset and the striate cortex a PN response complex; and (b) the striate cortex responds to finer patterns than the prestriate cortex.

Animals↗
PubMed1994

The analysis of motion of two-dimensional patterns: do Fourier components provide the first stage?

Human observers were required to report the direction of motion of simple two-dimensional (2-D) "plaid" patterns made by adding together two sinusoidal gratings of identical contrast (0.5 or 1.5 log units above threshold), spatial frequency (1 or 5 c/deg) and orthogonal orientations (horizontal and vertical, or +/- 45 deg). The patterns were made to move either by moving both gratings at the same speed (pattern motion) or by moving one component with the other stationary (component motion). In one task (direction discrimination) the observer knew the axis of motion, and was required to discriminate the direction of motion along that axis in a temporal two-alternative forced-choice paradigm; in the other task (direction identification) the observer did not know the axis of motion and was required to identify the direction of motion and the axis of motion. In both tasks the discrimination of pattern motion was consistently better than the discrimination of component motion, contrary to the predictions of the "two-stage" model of motion analysis, in which it is assumed that the motion of a 2-D pattern is calculated from the 1-D motions of its Fourier components. The variation in direction discrimination of pattern motion with speed did not have the form predicted under the assumption that the direction of motion of the pattern could be discriminated using the motion of either of its two component gratings. Finally, an elaborated version of the Adelson and Movshon [(1982) Nature, 300, 523-525] two-stage model, in which noise affects the two stages fails to predict the performance in identifying the pattern motion of the plaid pattern, except for 1 c/deg low contrast plaids. These results suggest that when 2-D patterns contain moderately high contrasts or high spatial frequencies observers may use other attributes, instead of, or in addition to Fourier components, to analyse their 2-D motion.

Discrimination, Psychological↗
PubMed2004

Intra-membrane ligand diffusion and cell shape modulate juxtacrine patterning.

A key problem in developmental biology is how pattern and planar polarity are transmitted in epithelial structures. Examples include Drosophila neuronal differentiation, ommatidia formation in the compound eye, and wing hair polarization. A key component for the generation of such patterns is direct cell-cell signalling by transmembrane ligands, called juxtacrine signalling. Previous models for this mode of communication have considered homogeneous distributions in the cell membrane, and the role of polarity has been largely ignored. In this paper we determine the role of inhomogeneous protein and receptor distributions in juxtacrine signalling. We explicitly include individual membrane segments, diffusive transport of proteins and receptors between these segments, and production terms with a combination of local and global responses to ligand binding. Our analysis shows that intra-membrane ligand transport is vital for the generation of long wavelength patterns. Moreover, with no ligand transport, there is no pattern formation for lateral induction, a process in which receptor activation up-regulates ligand production. Biased production of ligand also modulates patterning bifurcations and predicted wavelengths. In addition, biased ligand and receptor trafficking can lead to regular polarity across a lattice, in which each cell has the same orientation-directly analogous to patterns of hairs in the Drosophila wing. We confirm the trends in pattern wavelengths previously observed for patterns with cellular homogeneity-lateral inhibition tends to give short-range patterns, while lateral induction can give patterns with much longer wavelengths. Moreover, the original model can be recovered if intra-membrane bound receptor diffusion is included and rapid equilibriation between the sides is considered. Finally, we consider the role of irregular cell shapes and waves in such networks, including wave propagation past clones of non-signalling cells.

Animals↗
PubMed2005

The effects of opposite-polarity dipoles on the detection of Glass patterns.

Glass patterns--randomly positioned coherently orientated dipoles--create a strong sensation of oriented spatial structure. On the other hand, coherently oriented dipoles comprising dots of opposite polarity ("anti-Glass" patterns) have no distinct spatial structure and are very hard to distinguish from random noise. Although anti-Glass patterns have no obvious spatial structure themselves, their presence can destroy the structure created by Glass patterns. We measured the strength of this effect for both static and dynamic Glass patterns, and showed that anti-Glass patterns can raise thresholds for Glass patterns by a factor of 2-4, increasing with density. The dependence on density suggests that the interactions occur at a local level. When the Glass and anti-Glass dipoles were confined to alternate strips (in translational and circular Glass patterns), the detrimental effect occurred for stripe widths less than about 1.5 degrees, but had little effect for larger stripe widths, reinforcing the suggestion that the interaction occurred over a limited spatial extent. The extent of spatial interaction was much less than that for spatial summation of these patterns, at least 30 degrees under matched experimental conditions. The results suggest two stages of analysis for Glass patterns, an early stage of limited spatial extent where orientation is extracted, and a later stage that sums these orientation signals.

Humans↗
PubMed1997

Isolation and interaction of ON and OFF pathways in human vision: contrast discrimination at pattern offset.

Pattern contrast discrimination is typically studied with simultaneous onset of the base contrast (C) and added contrast (delta C) patterns. I measured contrast discrimination functions at pattern offset. A brief (30 msec) localized, spatially narrow-band D6 test stimulus was delta C. The onset of delta C was simultaneous with the offset of a large, 500 msec cosine pattern (the base contrast C). The D6 was either positive or negative contrast, and was masked by either positive or negative contrast, i.e., a light or dark bar of the cosine pattern. Stimuli were 3 cpd. Discrimination of negative delta C at the offset of positive contrast followed a "dipper" function, as if the OFF pathway were isolated. A dipper function was also obtained for a positive delta C at the offset of negative contrast (ON pathway isolation). But same-polarity delta C and C yield a monotonic discrimination function ("bumper" function) at the offset of C, suggesting inhibitory interaction. These discrimination functions for same-and opposite-polarity delta C and C are the reverse of functions obtained at pattern onset. Manipulations of temporal asynchrony between patterns and manipulations of pattern polarity are thus functionally equivalent in determining the form of the contrast discrimination function. In a second experiment, I determined delta C at times before and after the offset of a high-contrast C and manipulated pattern polarity. The time course of threshold change is different for same vs opposite-polarity test and mask. The results suggest that interaction between ON and OFF pathways is delayed relative to the masking process within a pathway. Interaction between pathways may function to improve temporal resolution by suppressing persistence of neural response in the complementary pathway. The present pattern polarity and temporal asynchrony effects on the contrast discrimination function also decisively falsify the "uncertainty" hypothesis for low-contrast threshold facilitation (the dipper).

Contrast Sensitivity↗
PubMed1998

Detection of global structure in Glass patterns: implications for form vision.

Glass (Nature 1969;223:578-580) patterns are random dot stimuli that generate a percept of global structure. To study the mechanisms underlying this global form perception, concentric, radial, hyperbolic, and parallel Glass patterns were constructed. Thresholds for detecting each type of pattern were measured by degrading the patterns through the addition of noise. Concentric patterns yielded the lowest thresholds for all subjects, while radial and hyperbolic patterns produced somewhat higher thresholds. For all subjects the parallel patterns produced the highest thresholds. Threshold measurements as a function of the area containing pattern structure provided evidence for global pooling of orientation information in the detection of radial and concentric Glass patterns but only local pooling in the detection of parallel patterns. Monte-Carlo simulations demonstrate that plausible neural models can accurately predict the data. These models indicate that the visual system contains networks that pool orientation information within regions 3.5-4.5 degrees in diameter in central vision. This pooling is organized to extract cross-shaped, X-shaped, and quasi-circular forms from the retinal image. The results are in good agreement with recent single unit physiology of primate area V4, an intermediate level of the form vision pathway.

Computer Graphics↗
PubMed1986

Horizontal-vertical structure in the visual comparison of rigidly transformed patterns.

Visual recognition of patterns reflected or rotated through 180 degrees (point-inverted) depends critically on their positional symmetry and separation in the field. A possible explanatory scheme suggested a description of internal pattern representation structures and simple internal operations that naturally involved a horizontal-vertical reference system. Predictions of the scheme were tested here in three experiments. Subjects made same-different judgments on pairs of random-dot patterns briefly presented in various arrangements and related by reflection, point-inversion, or identity transformation, or paired at random. Experiment 1 tested reflected patterns and verified the importance of orientation of the reflection axis relative to display-configuration axis. Experiment 2 demonstrated an oblique effect of configuration on performance with reflected patterns, but not with identical or point-inverted patterns. Experiment 3 demonstrated a vertical shift effect of configuration on performance with point-inverted patterns, but not with identical or reflected patterns. We concluded that in same-different pattern comparisons, a horizontal-vertical reference system appears fundamental in determining the nature of and operations upon internal pattern representations.

Adult↗
PubMed1994

Serial pattern learning after head injury.

Nonverbal serial pattern learning in patients with traumatic brain injury was examined using a serial reaction time task developed by Nissen and Bullemer (1987). During four blocks of pattern acquisition trials, subjects responded to asterisks appearing in repetitions of a 10-element spatial sequence. An indirect measure of pattern learning was obtained by comparing response times in the fourth pattern acquisition block with response times in a fifth block where asterisks occurred in random sequence. A direct measure of pattern memory was provided by accuracy scores in a final pattern generation block in which subjects predicted the spatial sequence of asterisks. Prior research with this task has shown that individuals from several special populations--including the normal elderly, Korsakoff's syndrome patients, and Alzheimer's patients--show intact performance on the indirect measure of pattern learning, but are impaired on the direct measure. In contrast to these earlier findings, the results of this study showed that mild to moderately severe traumatic brain injury does not cause a marked disruption in the ability to learn and remember serial pattern information. There was evidence that the amount of practice required to learn the serial pattern increases after moderately severe head injury; however, the ability to use pattern memory to enhance prediction accuracy appears to be normal.

Adolescent↗
PubMed2000

Systematic and fully automated identification of protein sequence patterns.

We present an efficient algorithm to systematically and automatically identify patterns in protein sequence families. The procedure is based on the Splash deterministic pattern discovery algorithm and on a framework to assess the statistical significance of patterns. We demonstrate its application to the fully automated discovery of patterns in 974 PROSITE families (the complete subset of PROSITE families which are defined by patterns and contain DR records). Splash generates patterns with better specificity and undiminished sensitivity, or vice versa, in 28% of the families; identical statistics were obtained in 48% of the families, worse statistics in 15%, and mixed behavior in the remaining 9%. In about 75% of the cases, Splash patterns identify sequence sites that overlap more than 50% with the corresponding PROSITE pattern. The procedure is sufficiently rapid to enable its use for daily curation of existing motif and profile databases. Third, our results show that the statistical significance of discovered patterns correlates well with their biological significance. The trypsin subfamily of serine proteases is used to illustrate this method's ability to exhaustively discover all motifs in a family that are statistically and biologically significant. Finally, we discuss applications of sequence patterns to multiple sequence alignment and the training of more sensitive score-based motif models, akin to the procedure used by PSI-BLAST. All results are available at httpl//www.research.ibm.com/spat/.

Algorithms↗
PubMed1997

Development of pattern visual evoked potentials: longitudinal measurements in human infants.

PURPOSE: This experiment used longitudinal testing to trace the emergence of the major components of pattern visual evoked potentials (VEPs) in infants, using two paradigms: large-checkerboard pattern reversal and low spatial frequency pattern onset. METHODS: Testing with both pattern-reversal and pattern-onset stimuli was performed on the same infants. Testing was conducted at weekly intervals during the first three postnatal months, and at intervals of 2 weeks to 1 month thereafter. RESULTS: The pattern-reversal and early pattern-onset responses recorded within individual subjects showed remarkably systematic developmental sequences. The broad, positive component seen at 200 to 250 ms in infants could be traced readily through the developmental sequence, to become the more sharply tuned positive component seen at about 100 ms in adults. Responses to low spatial frequency pattern onsets in infants were larger and more reliable than those in adults. The late components of the pattern-onset response, generally attributed to pattern offset, emerged later and with more complex changes. In all cases, response amplitude was much more variable than response latency, both within and between subjects. CONCLUSIONS: Frequent VEP recording in a longitudinal design can reveal systematic and detailed transitions of wave-form during development.

Adolescent↗
PubMed2002

Pattern discrimination in a hawkmoth: innate preferences, learning performance and ecology.

Spatial patterns are important cues for flower detection and recognition by nectar-feeding insects. Pattern vision has been studied in much detail in bees and flies but rarely in butterflies and moths. In this paper, I present a first proof of pattern-learning abilities in a moth, and discuss reasons for the limitations to their pattern learning. The diurnal hawkmoth Macroglossum stellatarum spontaneously prefers patterned to uniformly coloured stimuli but can be trained to choose the uniform stimulus. By contrast, experience does not override the innate preferences for radial over tangential patterns, and for tangential over striped patterns. These results do not reflect bad visual discrimination but rather a lack of learning ability and motivation to abolish innate preferences. I propose that radial and tangential flower patterns are good predictors of nectar reward, a condition under which learning is unlikely to evolve. These patterns serve not only as cues for flower detection but also as guides to the reward. Hovering pollinators strongly depend on these guides and should therefore: (i). have rigid pattern preferences; and (ii). not be motivated to abolish these preferences as easily as their innate preferences for colours.

Animals↗
PubMed1996

Micrometer resolution silane-based patterning of hippocampal neurons: critical variables in photoresist and laser ablation processes for substrate fabrication.

Toward the goal of creating patterns of primary hippocampal neurons in low density culture, we investigated techniques to fabricate microminiature grids of organofunctional silanes on glassy surfaces. A new photoresist (PR) process, Selective Silane Removal (SSR), was developed and compared to two previously developed techniques which use PR and laser patterning. The grid patterns consisted of 27 combinations of path width, length, and intersection (node diameter). The background consisted of squares bounded by the paths. The best neuron patterning was observed on substrates produced by the SSR process where cytophilic aminosilane is uniformly deposited and selectively removed from the background. Controlling water during aminosilane deposition was critical to good neuronal growth and patterning. Oxygen plasma etching of background regions prior to cytophobic phenylsilane binding significantly reduced off-pattern cell growth. Up to 90% of somata grown on these substrates complied to the pattern, and an average of 77% of background regions were free of neurites or cells connected to the pattern. The highest laser energy density, 120 mJ/cm2, produced the best compliance on lased substrates, with an average of 35% of background regions free of connected cells and neurites, but considerable variation across the surface. On substrates with excellent patterning, compliance to nodes was found to be dependent on pattern dimensions, with 20-micron node diameters and 80-micron internodal path lengths increasing compliance.

Animals↗