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Results for “spatial patterning”

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PubMed1992

Nucleoli and AgNOR proteins in 32 cases of primary breast carcinoma. Spatial pattern of interactions between 50 clinical and histometric criteria.

The purpose of this paper is to analyze a method allowing selection of the best morphometric criterion for quantifying AgNOR proteins under conventional observation conditions by light microscopy. We determined 50 parameters for 32 cases of primary breast carcinoma. For each case, three 100-nucleus samples (tumor center and periphery on a Giemsa-stained, 3-microns tumor section, periphery on a silver-stained section) were quantified. Distribution-free multidimensional data analysis was used to explore the geometric significance of the coefficient of correlation. This analysis revealed a clinical message linked with the largest "nucleolar structure" (nucleolus or AgNOR clump) per nucleus on the tumor periphery. Tumor recurrence or death correlated only with the coefficient of variation of the "nucleolar/nuclear" ratio of the greatest clump of AgNORs per nucleus periphery (CVRSa). The prognostic value of CVRSa is independent of that of conventional criteria, such as age, tumor size, Scarff-Bloom-Richardson grading and lymph node status. The largest AgNOR clump per nucleus may prove to be a further practical prognostic predictor.

Biometry↗
PubMed1985

Detection and characterization of spatial pattern in chimaeric tissue.

The mosaic pattern of patches of crypts of Lieberkühn in chimaeric C57BL/6JLac (B6)----DDK mouse small intestine, demonstrated using Dolichos biflorus agglutinin as strain-specific marker, is quantitatively examined using the Greig-Smith analysis of variance. This analysis, widely used in ecological research, provides a method to detect and characterize pattern at various scales. The analysis demonstrates that B6 patches are non-randomly distributed at all scales examined. A consistent increase in the intensity of pattern at one particular scale over all replicate samples identifies 'clusters of clusters' which probably are territories of 'descendent' clones. The sizes of descendent clones, either in terms of numbers of patches or total numbers of crypts, are highly variable. A steady reduction in the strength of pattern from proximal to distal is found. The Greig-Smith analysis of variance provides a valuable method for the analysis of pattern in chimaeric tissue.

Analysis of Variance↗
PubMed1978

Temporal and spatial patterns of the synthesis of tissue-specific polypeptides in the preimplantation mouse embryo.

Mouse embryos at different morphological stages in the transition from morula to blastocyst were analysed for the qualitative pattern of their polypeptide synthesis. The first appearance of the individual species of polypeptides specific to trophectoderm or ICM occurred progressively over this developmental period. Populations of inside cells recovered from morulae and early blastocysts synthesized those polypeptides previously shown to be characteristic of ICMs at 31/2 days, but not those characteristic of trophectoderm.

Animals↗
PubMed1990

Evolution of spatial cognition: sex-specific patterns of spatial behavior predict hippocampal size.

In a study of two congeneric rodent species, sex differences in hippocampal size were predicted by sex-specific patterns of spatial cognition. Hippocampal size is known to correlate positively with maze performance in laboratory mouse strains and with selective pressure for spatial memory among passerine bird species. In polygamous vole species (Rodentia: Microtus), males range more widely than females in the field and perform better on laboratory measures of spatial ability; both of these differences are absent in monogamous vole species. Ten females and males were taken from natural populations of two vole species, the polygamous meadow vole, M. pennsylvanicus, and the monogamous pine vole, M. pinetorum. Only in the polygamous species do males have larger hippocampi relative to the entire brain than do females. Two-way analysis of variance shows that the ratio of hippocampal volume to brain volume is differently related to sex in these two species. To our knowledge, no previous studies of hippocampal size have linked both evolutionary and psychometric data to hippocampal dimensions. Our controlled comparison suggests that evolution can produce adaptive sex differences in behavior and its neural substrate.

Animals↗
PubMed1988

A pattern formation mechanism to control spatial organization in the embryo of Drosophila melanogaster.

It is known that cells are already committed to a particular segment at the cellular blastoderm stage during embryogenesis of Drosophila melanogaster. Recently, several segmentation genes have been observed to be expressed in a sequence of banded spatial patterns in the syncytial blastoderm, prior to the formation of the cellular blastoderm. It is demonstrated in this paper that a two component reaction-diffusion (RD) system with net production functions which are antisymmetric with respect to the uniform steady-state values, is capable of producing a sequence of seven spatial patterns in the syncytial blastoderm. The sequence of patterns obtained exhibit a strong preference for banded or striped patterns. The first pattern is a simple anteroposterior gradient while the second is a gradient in the dorsoventral direction. The next five patterns are a sequence of banded patterns which exhibit frequency doubling, i.e. the number of bands in each pattern tend to be double the number in the previous pattern. The predicted pattern sequence is comparable to that observed in the expression of some segmentation genes. It is suggested that a pattern formation mechanism based on such an RD system may exist in the embryo where it produces a sequence of prepatterns to regulate the expression of various segmentation genes leading ultimately to a segmented embryo. There is sufficient spatial information in the sequence of banded prepatterns for the segments to be unique.

Animals↗
PubMed1979

Spatial firing patterns of auditory neuron network modelling by computer simulation.

This communication examines, in digital computer simulated network, input signals and response patterns established at excitatory neurons' level i.e. the membrane potential of neuron soma. It is restricted to spatial patterns of the auditory neuron networks and time factor for nervous conduction and transmission is neglected compared with long maintained membrane potentials of neuron somas. The model analyzes the change in the spatial patterns of the membrane potential in the two dimensional networks of the auditory system. In order to evaluate the contribution of the various parameters, it is started that the simplest model has only one parameter, lateral inhibition. The other parameters are then added, one at a time, to successive models. The lateral inhibition is a necessary condition in the auditory nervous system if any sharpening of the response areas in the single neurons is to occur. A necessary condition for the validity of the model is that is should be applicable to the other senses such as vision and chemical patterns, taste. The threshold feature of auditory neurons aids in producing a sharpening in the neuron of the auditory relay nuclei. It does this clipping the spatial response patterns in one dimensional arrays of excitatory neurons. Recurrent inhibition seems a necessary condition in the sensory nervous system that any kinds of input signals are to be preserved over a wide range of stimulus intensity. In other words, this network has a wide dynamic range against any kinds of input signals. A simple self-recurrent negative feedback does not contribute to the sharpening, but more complex socalled averaged type does. A neuron network is capable of responding stably to stimuli with a wide range of intensity and with any kind of spatial patterns if there is a simple negative feedback mechanism. When there is no negative feedback, input signals soon disappear or saturate in the neuron network. Therefore, recurrent inhibition is the most important mechanism. Spontaneous activity appears to aid in the sharpening by providing a kind of contrast, that is by reducting the amount of activity in neurons adjacent to the excitatory area. Moreover, the effect of spontaneous activity in the model seems to make repples around the excitatory area and suggests that an introduction of activity at any stage of the networks, from whatever source for example reticulum formation and thalamus, might appreciably alter the response patterns at subsequent neuron network. This suggests that the mechanism of the consciousness that might be controlled by the thalamus and or reticular formation. These two dimensional neuron networks may be expanded to three dimensional neuron networks. The former might simulate the auditory nervous system while the latter might simulate the visual system.

Animals↗
PubMed1988

A multipurpose vertical holeboard with automated recording of spatial and temporal response patterns for rodents.

A method is presented for manual or automated recording of rats' spontaneous nose-poking ('visit') behaviors to a vertical holeboard with a matrix of 45 or 54 holes. Several behavior parameters are presented: visit frequency, visit duration, temporal visit pattern, spatial visit pattern, stereotype of visits, diversity of visits and variability of visit patterns. The paper describes the development of the apparatus and some methods of analyzing and presenting the multi-parametric data. The use of the apparatus is illustrated with a one-trial appetitive conditioning task. After 5 min in a single 10-min session, a food pellet is presented, only once in a given hole, to provide reinforcement of a spontaneous visit to that hole. The behavior parameters are compared before and after reinforcement. When the one-trial conditioning effect was challenged with d-amphetamine, the behavior parameters changed in a graded manner depending upon the dose (0.25-6.0 mg/kg). The apparatus has also proven useful for studies of exploratory behavior without using food reinforcement following lesion or drug interventions.

Animals↗
PubMed1992

From stripes to spots: prepatterns which can be produced in the skin by a reaction-diffusion system.

A key question in the area of spatial pattern formation in developmental biology is: how do groups of cells in a homogeneous tissue suddenly differentiate along entirely different developmental paths compared to neighbouring cells? Although experiments are now beginning to provide answers to this question, the mechanisms responsible for the development of repeated or periodic structures and spatial patterns, e.g., hair follicles and pigmentation patterns, are still unknown. Theoretical biologists and applied mathematicians have suggested various prepattern mechanisms as the primary cause of repeated or periodic spatial patterns. A class of biochemical reactions referred to here as reaction-diffusion (RD) systems, having the capacity to spontaneously generate stable stationary wavelike spatial patterns (Turing, 1952), has been suggested as a possible prepattern mechanisms, e.g., during hair follicle initiation and development (Nagorcka, 1989), and pigmentation patterns (Murray, 1989). Spatial patterns arising during development of the vertebrate skin are frequently complex. Spatial patterns in the skin can be seen to vary within an individual from one region of the skin to another. One pattern change commonly observed across the skin is from stripes to spots. An RD system is defined which is able to generate different spatial patterns depending on the value of a single parameter. The parameter varied controls the transport of the chemical components of the RD system across the basement membrane separating the epidermis and dermis. The patterns produced range from stripes to an irregular array of spots. Not only are different patterns produced, but a different time sequence of prepatterns is expected to arise in the different skin regions depending on whether the first prepattern in an array of spots or stripes. As a consequence it is possible to account for hair follicle initiation in the hair-bearing regions of the mammalian skin as well as the sequence of events required for the formation of dermatoglyphics in the volar regions.

Animals↗
PubMed1990

Prediction of apical thrombus formation in acute myocardial infarction based on left ventricular spatial flow pattern.

The predictive value of the left ventricular spatial flow pattern for thrombus formation was determined in 62 patients with acute myocardial infarction. A normal flow pattern by pulsed Doppler echocardiography was characterized by 1) simultaneous onset of blood motion at the mitral valve and apical level, and 2) a discontinuous Doppler signal along the lateral wall and interventricular septum. The flow pattern was assessed by these criteria, within 24 h after the onset of complaints and after 6 and 12 weeks. In 46 of the 62 patients, a normal flow pattern was found at the first examination; none of these 46 patients developed a thrombus during the study period. An abnormal flow pattern was seen at the first examination in 16 patients; this pattern normalized during follow-up in 6 patients, none of whom developed a thrombus. In the other 10 patients the abnormal flow pattern persisted, and 7 of these developed a thrombus. These findings suggest that a normal left ventricular flow pattern in the setting of acute myocardial infarction is not associated with subsequent thrombus formation. This observation may be of importance if anticoagulation is considered.

Aged↗
PubMed2026

Spatial inheritance patterns across maize ears are associated with alleles that reduce pollen fitness.

Often, more pollen grains land on recipient flowers than there are ovules to fertilize. Consequently, the haploid male gametophyte engages in post-pollination competition, one way that pollen genotype can influence inheritance. The maize (Zea mays subsp. mays L.) inflorescence (ear), with its elongated stigma and style structures (silks), has a conspicuous spatial heterogeneity, with longer silks at the base of the ear than at the apex. To evaluate the hypothesis that alleles with reduced pollen fitness influence the spatial distribution of progeny genotypes along the ear, we developed an updated phenotyping platform that maps fluorescently marked mutant (Ds-GFP) kernel phenotypes on the ear via an implementation of the Faster R-CNN machine vision model (EarVision.v2) and a statistical pipeline that evaluates the relationship between kernel position and transmission ratio (EarScape). Our dataset (1384 ears) represents 58 Ds-GFP insertion alleles. None of the 48 alleles with Mendelian inheritance showed any significant spatial trend. In contrast, 50% of alleles with a pollen-specific transmission defect (5/10) exhibited significant spatial effects. An insertional mutant of the gene encoding a putative actin-binding protein, base-to-apex gradient1* (bag1*), is associated with decreased mutant transmission at the ear base relative to the apex. Surprisingly, a mutant allele of another pollen-expressed gene (Zm00001eb236740) generates the opposite trend, decreased mutant transmission toward the ear apex; and two mutant alleles of the sperm cell attachment factor gamete expressed2 (gex2) can produce ears with transmission highest at both base and apex. We conclude that pollen fitness mutants cause unexpectedly diverse spatial patterns of progeny genotypes.

Zea mays↗