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PubMed1988

Representing and defining patterns by graphs: applications to sol-gel patterns and to cytoskeleton.

The problems of interdisciplinary interests--applying methods of graph theory to sol-gel patterns and to cytoskeleton--are discussed. The importance of sol-gel transition phenomena in living cells and the possibility of periodic sol-gel transition phenomena are briefly reviewed. Representing patterns by graphs and using graph probabilistic representation for calculating structure-property relationships are discussed and applied to sol-gel transition patterns.

Biometry↗
PubMed1991

Human tactile pattern recognition: active versus passive touch, velocity effects, and patterns of confusion.

1. Subjects without any previous experience in a tactile psychophysics task participated in a study of tactile letter recognition employing active and passive touch. In the active task, subjects reached through a curtain and examined embossed letters with horizontal, unidirectional finger strokes. In the passive task, subjects sat with their arms and hands immobilized while a rotating drum stimulator pressed the embossed letters onto the right index finger. The stimulus conditions in the passive task were identical to those used in neurophysiological experiments with monkeys. 2. A survey of 40 naive subjects who were not screened in any way showed a wide range of performance levels. There was no difference between the subjects in the active and passive tasks, either in overall mean percent correct scores, which were 49.0 and 50.7%, respectively or in the percent correct scores for individual letters whose product-moment correlation coefficient was 0.94. The active and passive groups, which contained 25 and 15 members, respectively, had no members in common. 3. Videotapes of the finger movements of eight subjects in the active task showed a characteristic V-shaped velocity profile (velocity vs. lateral position) starting at approximately 100 mm/s at the left-hand edge of the plate containing the embossed letter, decelerating to a minimum when the center of the finger was directly over the letter, and then accelerating away from the letter. The average minimum scanning velocity was 17 mm/s. 4. Scanning velocity had no significant effect on performance in the passive task between 20 and 40 mm/s. An increase to 80 mm/s produced a 16% decline in percent correct identifications. 5. Learning effects were evident across sessions even though subjects were given no feedback or training. The increase in mean percent correct judgments averaged 4% per session, which lasted for approximately 1 h. 6. Data from 64 subjects were pooled for detailed comparison of identification patterns in active and passive touch. The results were analyzed and found to be consistent with the hypothesis that the identification and confusion probabilities are identical in the two modes. We conclude that there is no difference between active and passive touch in form recognition when the stimulus pattern is smaller than a finger pad. 7. Data from all experiments were pooled to produce a single confusion matrix with 324 presentations per letter. The majority of erroneous responses are grouped in a small number of confusion pairs and the majority of those confusion pairs are strongly asymmetric. The probable neural mechanisms of some confusion patterns are discussed.

Adult↗
PubMed1991

[Atrophy of the ganglion cells reduces pattern ERG not only in fine but also in coarse test patterns].

The pattern electroretinogram (PERG) is thought to be generated by the retinal ganglion cells. For coarse patterns, however, it has been suggested that the PERG is due to nonlinear summation of luminance responses. To test this hypothesis, we recorded the PERG in 8 patients with unilateral complete optic atrophy due to trauma or advanced glaucoma. Stimuli were phase-reversing checkerboards (7.8/s) with checks of 0.8 degrees and 15 degrees in size and with flashes. Retinal stimulation subtended 26 degrees x 34 degrees. In all 8 subjects, the PERG was greatly diminished using a check size of 0.8 degrees. With a check size of 15 degrees, the PERG was similarly diminished, while the flash responses were not reduced. Any overall luminance component of the stimulus, e.g., incomplete balance of light and dark areas, evoked strong luminance responses both in normal eyes and in eyes with optic nerve atrophy. Thus, intact ganglion cells seem to be necessary for a normal PERG regardless of the coarseness of the pattern. It is possible that different mechanisms (variable ganglion cell classes) contribute to the PERG response with different check sizes. Earlier reports, contradictory to these findings, are discussed. If the PERG reflects ganglion cell function even for large check sizes, stimulation of the ganglion cells with less optical degradation would be possible, enlarging its range of applications.

Attention↗
PubMed1987

Computation of the luminance and pattern components of the bar pattern electroretinogram.

Pattern onset electroretinograms (PERGs) were recorded from four normal subjects. Square-wave gratings of 75% contrast were presented in three approximately contiguous, concentric zones of outer angular radius, 5.1 degrees, 12.6 degrees, and 23.6 degrees. The zones were calculated to give equal numbers of ganglion cell receptive fields. The recorded PERGs were considered to include luminance and pattern components which have low and bandpass spatial tuning functions respectively. These components combine in the PERG to produce a broad spatial tuning characteristic. The amplitude of PERGs in response to low spatial frequency stimuli is widely reported to be linearly related to contrast. The retinal illuminance response at every spatial frequency was computed from the eye's modulation transfer function. This function characterizes the reduction in contrast that occurs because of optical degradation. The computed retinal illuminance response was subtracted from the PERG waveform and a pattern-specific response was revealed. The latter had a highly tuned bandpass function which peaked at higher spatial frequencies than the PERG at corresponding peripheral angles.

Electroretinography↗
PubMed1985

Flash and pattern presentation and pattern-reversal evoked potentials in multiple sclerosis.

The visual evoked potential (VEP) results for 404 multiple sclerosis (MS) patients are presented. In 171 patients pattern reversal with light-emitting diode (PR (LED] VEPs and in 85 patients pattern reversal with TV (PR(TV] VEPs also were investigated. The pathologic process of MS affects the amplitude and latency of all components and the form and symmetry of responses. A complex evaluation of VEP is proposed instead of measurement of only one component. A combined flash and pattern presentation VEP evaluation may be as effective as PREPs in the detection of subclinical lesions. PR(LED) VEP seems to be more sensitive to the degree of visual disturbance and to the clinical probability of MS than the PR(TV) VEP. A statistical analysis disclosed correlation of VEP amplitude and latency data with the visual impairment, one with the duration and multiplicity (generalization) of the disease. Combination of different methods increases the discriminative power of the VEP investigation.

Adult↗
PubMed1988

Evidence for central entrainment of the medullary respiratory pattern by the locomotor pattern in the rabbit.

1) Although periodic passive hindlimb movements can reproduce the enhancement of breathing frequency seen at the onset of muscular exercise, we have shown previously that they were unable to induce the 1:1 coupling which is observed between locomotion and respiration during galloping in quadrupeds. The purpose of this study was to investigate the existence of a central coupling in two experimental situations: first, decorticate - DOPA, and secondly, decerebrate rabbit preparations. 2) After DOPA administration in curarized, vagotomized, decorticate animals, an absolute coordination could be observed between the locomotor bursts (which developed in hindlimb muscle nerves) and phrenic activity. With the temporal evolution of the pharmacological activation, the coupling mode varied from 1:1 to 1:2 during the same experiment with a loss of coordination between these two forms. When the coordination between both motor activities was not produced in such conditions, it could be induced for some imposed frequencies of periodic passive motions applied to the contralateral hindlimb. 3) When the DOPA effects were completely over, a rostro-pontine decerebration allowed locomotor activity to be released and a tight 1:1 coupling could be obtained again between the two motor patterns in this new experimental situation. 4) An analysis of the data revealed that the various forms of coordination obtained in the different experimental situations are due to a central resetting of the respiratory and of the locomotor patterns. The capability of the hindlimb proprioceptive inputs to coordinate locomotor and respiratory patterns in the decorticate-DOPA preparation appeared simply linked to their ability to entrain the activity of the lumbar locomotion generator. It is suggested that these central reciprocal interactions, which have the properties of an entrainment process, are the result of interactions between the lumbar locomotion generator and the medullary respiratory one.

Action Potentials↗
PubMed1979

[Patterns of fetal heart frequency during the second stage of labour and expulsion period--typical patterns, frequency, risk of acidosis and evaluation (author's transl)].

Four patterns of fetal heart frequency with normocardia, two with tachycardia and three with bradycardia are described during the expulsion period. The most frequent patterns are normocardia with decelerations (48%), normocardia with decelerations and final bradycardia (21.1%) and basal bradycardia with decelerations (13.5%). The frequency of acidosis (pH of the umbilical artery less than or equal to 7,200) of these three patterns amounts to 8.3, 24.1 respectively 26.7%. The mean values of pHUA of normocardia with decelerations and final bradycardia, bradycardia, bradycardia with decelerations, tachycardia with decelerations and final bradycardia with prepathologic respectively pathologic Scores (Hammacher's Score, greater than or equal to five points) range from preacidosis to acidosis. Scoring of cardiotocograms seems to be of greater clinical significance than the measurement of deceleration areas.

Acidosis↗
PubMed1987

Image processing and pattern recognition algorithms for evaluation of crossed immunoelectrophoretic patterns (crossed radioimmunoelectrophoresis analysis manager; CREAM).

A computerized method for automatic evaluation and comparison of crossed immunoelectrophoretic and crossed radioimmunoelectrophoretic patterns that requires limited hardware resources has been developed. For the initial reading of the plates an ordinary video camera is used. Feature extractors that allow the computer to recognize a point on the precipitation curve as being a peak point have been developed. After this automatic procedure the program allows for an interactive menu-driven proofreading phase during which it is possible to force the system to take into consideration any number of extra points along the precipitation curve in the curve-fitting process. The system has been tested on crossed immunoelectrophoretic patterns as well as crossed radioimmunoelectrophoretic patterns and it has been shown that the system can recognize the same precipitation curves on different immunoplates and autoradiographs. In addition, the system reports the mean, the variance, and the area of the precipitation curves, thus allowing not only a qualitative comparison of two or more plates but also a quantitation of individual antigens or antibodies.

Algorithms↗
PubMed1987

Palisading pattern of subpial astroglial processes in the adult rodent brain: relationship between the glial palisading pattern and the axonal and astroglial organization.

The architectural organization of the subpial astrocyte processes was examined near the brain surface by single immunostaining methods. The astroglial processes were stained on brain sections made parallel to the pial surface. The astroglial glial fibrillary acid protein (GFAP) antigen was used as a specific marker. We show that these subpial astrocyte processes present a well organized palisading pattern in the adult mouse and rat spinal cord, medulla and pons. This adult astrocyte palisading pattern is compared to the palisading radial glia organization we previously demonstrated in the fetal mouse brain. The observed analogies afford a new and strong argument in favor of a derivation of the subpial astrocytes from radial glia. Double immunostaining methods, using GFAP and neurofilament antigens as glial and neuronal markers respectively, show the close relationship existing between the trajectories of axonal and glial processes. Beside the colinearity already observed between the axon trajectories and the glial palisades we demonstrate a new kind of axon/glia relationship. Axons are closely intermingled, within the palisading glial tufts, with the peripheral processes of the subpial astrocytes progressing to the pial surface. The findings suggest that fetal radial glia organization has a direct and indirect influence on the adult astroglial and perhaps the axonal pattern.

Animals↗
PubMed1991

Pharmacophoric pattern matching in files of three-dimensional chemical structures: use of smoothed bounded distances for incompletely specified query patterns.

This paper describes a technique for increasing the screen-out of pharmacophoric pattern searches in the databases of three-dimensional chemical structures when only some of the interatomic distances in the query pattern are specified. The technique involves the application of a distance bounds-smoothing procedure to the query distances; this smoothing allows the calculation of upper and lower bounds for the unspecified distances. The bounded distances can then be used to set screens additional to those that are set to describe the distances that have been specified by the searcher. Evidence is presented to suggest that use of the technique can lead to increases in the efficiency of substructure searches for partially specified query patterns.

Databases, Factual↗
PubMed2025

Dual-patterned pluripotent stem cells self-organize into a human embryo model with extended anterior-posterior patterning.

Human gastruloids are a powerful class of stem cell-derived models that recapitulate key features of early embryonic development, including symmetry breaking and the emergence of three germ layers1-3. However, they lack anterior embryonic structures and coordinated axial organization4-6. To address this limitation, we pre-patterned human pluripotent stem cells (hPSCs) by exposing them to either anterior (FGF2) or posterior (CHIR99021 [CHIR] & retinoic acid [RA]) cues. Upon mixing, these dual-patterned hPSCs interacted and self-organized into elongated structures with both anterior and posterior features-which we term anterior-posterior (AP) human gastruloids. Anteriorly pre-treated cells robustly intercalated into posteriorly pre-treated cells, collectively giving rise to a continuum of neural tissues-including a brain-like domain, a neural tube-like structure, and neuro-mesodermal progenitors (NMPs)-with segmented somites arrayed bilaterally. Single cell RNA sequencing (scRNA-seq) revealed that human AP gastruloids contain cell types resembling the midbrain-hindbrain boundary (MHB), regionalized hindbrain structures (i .e. rhombomeres 1-8), regionalized neural crest (i.e. cranial, vagal, trunk)7,8 and head mesoderm. Transcriptomic comparisons to primate embryos revealed that human AP gastruloids most closely resemble Carnegie stage 11 (CS11) embryos. While they lack a notochord and full dorsal-ventral polarity, human AP gastruloids recapitulate key spatial and temporal features of early neurulation and somitogenesis. Perturbation of folic acid metabolism or rho-associated kinase (ROCK) signaling induced spinal cord defects, phenocopying aspects of spina bifida and other neural tube defects, highlighting this model's potential for studying congenital disorders9. AP gastruloids may serve as a simple, robust, scalable platform for modeling coordinated human AP body axis development. More broadly, our results suggest that controlled interactions between differentially prepatterned progenitors can initiate self-organization of complex body axis features. The "pattern-and-mix" strategy may serve as a generalizable framework for assembling spatially organized stem cell models of mammalian development.

Journal Article↗
PubMed1991

Neurons that form multiple pattern generators: identification and multiple activity patterns of gastric/pyloric neurons in the crab stomatogastric system.

1. The stomatogastric ganglion (STG) of decapod crustaceans has been characterized by its production of two motor patterns, the gastric mill rhythm and the pyloric rhythm. The period of the gastric rhythm is typically 5-10 s, whereas the period of the pyloric rhythm is approximately 1 s. 2. In the STG of the crab, Cancer borealis, we find routinely that many motor neurons are active in time with both the pyloric and gastric rhythms. We rigorously identified the motor neurons according to the muscles they innervate. Some neurons usually classified as members of the pyloric network can be active in time with the gastric rhythm. All of the gastric motor neurons except the dorsal gastric (DG) neuron can generate pyloric-timed firing patterns. 3. Two motor neurons innervate muscles found in several different regions of the stomach. The inferior cardiac (IC) neuron, usually considered part of the pyloric network, innervates cardiac sac, gastric mill, and pyloric muscles. The lateral posterior gastric (LPG) neurons innervate muscles of both the gastric mill and the pyloric chamber. 4. These data show that the gastric and pyloric networks in the crab are not separate groups of neurons that independently generate two different rhythmic behaviors. Rather, these neurons together provide a synaptically connected pool of neurons from which many different pattern-generating circuits can be assembled, under different physiological conditions.

Action Potentials↗
PubMed1987

Dynamics of the control of body pattern in the development of Xenopus laevis. IV. Timing and pattern in the development of twinned bodies after reorientation of eggs in gravity.

The mesendodermal anatomy of twinned larval axes is described in relation to the normal single pattern, when twinning has been caused by experimental tilting of eggs before first cleavage. The formation of two origins for gastrulation movements (dorsal lips) and their relatively rapid spread and coalescence to give a circular blastopore, is a predictor of twin formation in individual embryos after treatment. The anatomy of twins where development has been disturbed from the outset in this way is appreciably different from that induced by the later operation of second dorsal lip implantation. It is also variable in a systematic way. The total sizes of cellular allocations to individual notochords and prechordal head patterns are enhanced above normal if they arise relatively close together in the tissue, but significantly reduced if they arise far apart. These and other features of twinned patterns due to precleavage disturbance are discussed in terms of what they might indicate about the physicochemical nature of the body positional system. The results confirm that by a variety of rather simple, nonsurgical manipulations the relative amounts of territory in the egg devoted to different parts of the body can be greatly influenced.

Animals↗
PubMed1977

Comparative study of axopodial microtubule patterns and possible mechanisms of pattern control in the centrohelidian heliozoa Acanthocystis, Raphidiophrys and Heterophrys.

The axopodial microtubule pattern of 9 centrohelidians belonging to the genera Acanthocystis, Raphidiophrys and Heterophrys, as well as the fine structure of their microtubule organizing centre, the centroplast, was studied to determine the rules which govern their patterns. Microtubules capable of binding a xamimum of 4 linkers are arranged in regularly distorted hexagons and equilateral triangles. The number of microtubules present in each axoneme ranges from some 140 in Acanthocystis turfacea to as few as 6 in Heterophrys marina (Stock I). In the later species each axoneme contains a single hexagon of microtubules only. In other Heterophrys species, the central hexagon is surrounded by closely packed microtubules or by microtubules arranged in pentagons; only the central hexagon is anchored in the centroplast shell, whereas additional microtubules seem to originate from secondary nucleation sites somewhat distal to the centroplast. It is argued that the distortion of the basic unit hexagon (with alternate angles close to 134 degrees and 106 degrees) indicates that the microtubules are composed of 13 protofilaments. While in the larger Acanthocystis and Raphidiophrys species, the pattern may result from self-linkage, the arrays found in the Heterophrys species seem to favour a template-determined linkage. To explain the formation of the central hexagon in Heterophrys and balanced lateral growth in the larger microtubule arrays, a 'linker-nucleation hypothesis' is proposed. The assumption is made that graded conformational changes in the microtubule subunits not only specify the position where the next linker will bind, but that this linker, through linkage, becomes able to induce secondary microtubule nucleation, which will result in balanced lateral growth of the array. The application of this hypothesis to other microtubule systems, e.g. basal body formation, is discussed.

Animals↗
PubMed1990

[Distribution pattern of chemicals in surface waters as a reflexion of entry pattern--description of the problems].

The distribution pattern of persistent substances made transparent chemically-analytically, in surface waters reflects--considering spatial-temporal limitations--an image of the input pattern. This permits in special cases repercussions on attributable (industrial enterprises, trade, plant production, pest control) or partly or completely anonymous (landfills, ancient deposits, contamination centres, traffic, atmospheric depositions) causative agents The classification of these information requires the knowledge of substance and substrate specifics, especially detailed information about production and/or application of the substances and so represents an interdisciplinary task. Assessing single substance analyses permits a comparison with limit values or literature data. The consideration of combinations of substances which belong together due to production, application and/or transformation may help to elucidate the input patterns. This differential-diagnostic method is presented by a first evaluation of analytical findings in surface waters of an industrialized town and its surroundings.

Hydrocarbons, Halogenated↗
PubMedDate not supplied

Biotyping of Haemophilus paragallinarum isolates using hemagglutinin serotyping, carbohydrate fermentation patterns, and antimicrobial drug resistance patterns.

Three techniques, a hemagglutinin (HA) serotyping scheme, carbohydrate fermentation patterns, and antimicrobial drug resistance patterns, were used to examine 92 isolates of Haemophilus paragallinarum. The results were used to create biotyping schemes. The carbohydrate fermentation and antimicrobial drug resistance patterns each resulted in the identification of five biovars. With both of these techniques, a large majority of the isolates fell into one biovar: 81% were biochemical biovar I and 73% were antimicrobial biovar I. However, by combining the results of these techniques with those of the HA serotyping, a much greater discrimination could be achieved. The combined use of hemagglutinin serotyping, biochemical biotyping and antimicrobial biotyping appears to provide a suitable approach for epizootiological studies on infectious coryza.

Bacterial Typing Techniques↗
PubMedDate not supplied

A change of urinary proteins from a glomerular pattern to a tubular pattern during a late diuretic phase of acute renal failure.

The proteinuria on admission, on the 3rd day of the disease, of a 15-year-old male patient with acute renal failure (vasomotor nephropathy) showed a glomerular proteinuria-predominant pattern, and had a normal activity of N-acetyl-beta-D-glucosaminidase, indicating little proximal tubular damage. During a late diuretic phase, the excretion of N-acetyl-beta-D-glucosaminidase in the urine increased in accordance with increases of sodium excretion and urine flow, and then decreased to the normal range on the 20th day of the disease. Urine during the late diuretic phase showed a tubular proteinuria pattern and finally returned to a normal pattern on the 47th day of the disease. Thus, transient proximal tubular damage was evidenced in the late diuretic phase of the patient.

Acetylglucosaminidase↗
PubMed1986

Suppression-burst pattern associated with generalized epileptiform discharges and alpha-theta pattern coma.

In this paper we reported a patient with multisystem failure, whose EEG immediately preceding death demonstrated a unique combination of suppression-burst pattern, generalized epileptiform discharges, and alpha-theta pattern coma. Post-mortem examination showed ischemic-anoxic lesions involving cortical and sub-cortical gray matter. The lack of white matter pathology in our patient indicates that white matter lesions may not be involved in the pathogenesis of the above EEG patterns in anoxic encephalopathy.

Aged↗