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At least 127 records · Page 7Linked to original sources
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↗
PubMed1992

Temporal and spatial expression patterns of the small heat shock (hsp16) genes in transgenic Caenorhabditis elegans.

The expression of the hsp16 gene family in Caenorhabditis elegans has been examined by introducing hsp16-lacZ fusions into the nematode by transformation. Transcription of the hsp16-lacZ transgenes was totally heat-shock dependent and resulted in the rapid synthesis of detectable levels of beta-galactosidase. Although the two hsp16 gene pairs of C. elegans are highly similar within both their coding and noncoding sequences, quantitative and qualitative differences in the spatial pattern of expression between gene pairs were observed. The hsp16-48 promoter was shown to direct greater expression of beta-galactosidase in muscle and hypodermis, whereas the hsp16-41 promoter was more efficient in intestine and pharyngeal tissue. Transgenes that eliminated one promoter from a gene pair were expressed at reduced levels, particularly in postembryonic stages, suggesting that the heat shock elements in the intergenic region of an hsp16 gene pair may act cooperatively to achieve high levels of expression of both genes. Although the hsp16 gene pairs are never constitutively expressed, their heat inducibility is developmentally restricted; they are not heat inducible during gametogenesis or early embryogenesis. The hsp16 genes represent the first fully inducible system in C. elegans to be characterized in detail at the molecular level, and the promoters of these genes should find wide applicability in studies of tissue- and developmentally regulated genes in this experimental organism.

Animals↗
PubMed1991

The temporal and spatial distribution pattern of maternal exuperantia protein: evidence for a role in establishment but not maintenance of bicoid mRNA localization.

The exuperantia (exu) gene of Drosophila melanogaster plays a fundamental role in the establishment of polarity of the oocyte and early embryo by ensuring the proper localization of the mRNA of the bicoid (bcd) gene to anterior regions of the oocyte. We have isolated and sequenced the exu gene, sequenced its female-specific transcript and a mutant allele of exu that affects primarily exu's female germline function, and determined the temporal and spatial pattern of exu protein expression during oogenesis. The exu protein is basic, with at least one basic residue being identified as necessary for exu function in the female germline, and is present transiently during oogenesis. Our results suggest that exu is not required for the maintenance of bcd mRNA localization during late stages of oogenesis and early embryogenesis, but rather for the establishment of bcd mRNA localization in the developing oocyte. We propose that the exu protein may serve to modify a component that binds bcd mRNA or to modify the bcd message itself, or may perform a role in docking the bcd mRNA at its site of localization in the developing oocyte.

Amino Acid Sequence↗
PubMedDate not supplied

ABH antigen secretion in Basques and the spatial variation pattern of the secretor locus in Spain.

Secretion of the ABH blood group antigen was analyzed in 305 saliva samples of students in the Basque Country University. The frequency of ABH non-secretor was 26.23%, a result very close to that obtained in autoctonous Basques (22-23%) and in other populations from the West (Galicia) and Centre (Castille) of Spain. With certain exceptions, the frequencies of non-secretor se allele present a fairly homogeneous variability pattern and no significant spatial orientation or tendencies of se gene distribution are observed in the Iberian Peninsula.

ABO Blood-Group System↗
PubMed1987

Developmentally regulated rat brain mRNAs: molecular and anatomical characterization.

In order to identify markers for developing neural cell populations and gain molecular insights into the processes of neural development and differentiation, we have selected cDNA clones of rat brain mRNAs that are expressed in brain at embryonic day 16 (E16) with at least 10-fold greater abundance than they are in adult brain. Eleven such clones were obtained from a cDNA library of E16 brain poly(A)+ RNA using a combination of differential and subtractive hybridization screens. The temporal and spatial patterns of expression of the mRNAs corresponding to these clones were characterized by Northern (RNA) blotting and by in situ hybridization. Although all the mRNAs were enriched in embryonic brain, different mRNAs demonstrated maximum abundance at different times in late embryogenesis. The mRNAs can be grouped into 3 classes on the basis of their patterns of spatial expression in the embryo: one cDNA clone from each class and its corresponding mRNAs have been characterized in more detail. Class C represents mRNAs that are highly enriched in the nervous system and may be expressed in newly differentiating neurons; the example chosen was shown by nucleotide sequence analysis to encode the brain alpha 1 isotype of tubulin. Class B mRNAs have a broader distribution in the developing embryo but are expressed predominantly in the ventricular germinal zones of the developing nervous system and may represent molecules involved with neurogenesis. A third class (Class A) includes mRNAs with a more homogeneous distribution within the embryo and developing nervous system, which may encode "housekeeping" molecules. These clones and their encoded products will provide markers for cell populations at particular stages of neural development.

Animals↗
PubMed1990

Optical assessment of spatially ordered patterns of neural response to vagal stimulation in the early embryonic chick brainstem.

Spatial dynamic patternings of electrical responses to vagal nerve stimulations in the embryonic chick brainstem preparation were assessed by means of simultaneous multiple-site optical recordings of electrical activity. The vagus/brainstem preparations were dissected from early 7-day-old chick embryos (165-172 h after incubation), and they were stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761). Application of depolarizing square current pulses to the vagus nerve fibers using a suction electrode evoked voltage-related optical (absorbance) signals that were recorded simultaneously from 127 contiguous sites in the whole brainstem preparation using a 12 x 12-element photodiode array. The optical signals evoked by the vagus nerve stimulation appeared to be concentrated longitudinally in the central region and in the lateral region ipsilateral to the site of brainstem stimulation. These response areas were orderly changed according to changes in the strength and in the duration of the stimulating current: the response area expanded as the strength or the duration of the stimulating current was increased. The size of the evoked optical signals also depended on the strength and on the duration of the stimulating current. We also measured critical (threshold) values of the strength and duration of the stimulating current to produce the optical responses, and we found that there was a regionally ordered distribution in the brainstem. In the experiments on transverse slices of the brainstem, the evoked optical responses were detected from limited areas near the dorsal surface of the stimulated side, and the response pattern depended on the strength and duration of the stimulating current in a manner similar to that in the whole brainstem preparations. On the basis of the data obtained from these experiments, we have constructed 3 kinds of response maps for the embryonic brainstem, and the results suggest the functionally ordered arrangement of the neurons in the vagus-related area in the embryonic brainstem.

Animals↗
PubMed1985

Spatial EEG patterns, non-linear dynamics and perception: the neo-Sherringtonian view.

Spatial analysis with preamplifier arrays and computers offers fresh perspectives on brain function. Realization of its potential depends on development of appropriate procedures for data processing and display, experimental paradigms to serve as benchmarks, and theories of brain function to predict what to look for and how to distinguish valid results from artifacts. Measurement of EEGs from arrays of 64 electrodes chronically implanted on the olfactory bulbs of rabbits that are trained to discriminate odorant conditioned stimuli show that the odorants induce spatially distinctive amplitude patterns of neural activity. The odor-specific information density is inferred to be uniform over the whole main bulb. The neural dynamics that produce these activity patterns emerge from the synaptically interactive sheet of excitatory mitral and inhibitory granule cells with distributed input and output tracts and with static nonlinearities deriving from the nerve impulse mechanism. Excitatory synapses between mitral cells are subject to modification when odorants are paired with unconditioned stimuli, thus forming nerve cell assemblies. Odorant-specific information established by a stimulus locally in the bulbar unit activity is integrated with past experience by an assembly, disseminated over the entire bulb on the order of 100 mm2 in area in a time period of 2.5 ms, and sustained for a time period on the order of 0.1 s. An arbitrary spatial sample on the order of 20% of bulbar EEG activity captures the entire integrated information albeit at lesser resolution than the whole. This synaptic mechanism of local input and global output may be common to all of the cerebral cortex. The implications are discussed for neocortical sensory systems, motor pattern generators, and goal-directed behavior in the context of self-organizing non-linear dynamic systems.

Aging↗
PubMed1987

Single fiber mapping of spatial excitation patterns in the electrically stimulated auditory nerve.

Spatial maps of electrical excitation were constructed by comparing electrical threshold with acoustic CF for large populations of auditory nerve fibers in cats. Thresholds among fibers with the same CF varied by factors of 4 or more. Monopolar electrodes, both intracochlear and extracochlear, excited fibers throughout the cochlea without spatial selectivity. Stimulation with intracochlear bipolar electrodes produced a minimum in the threshold distribution adjacent to the electrodes. With longitudinally oriented pairs, the width, depth, and location of the minimum shifted with stimulus polarity; spread of excitation throughout the cochlea occurred with stimulus intensities 6.2 to 14 dB above the lowest threshold. With radially oriented pairs, minima were sharper and deeper; spread of excitation occurred at intensities 23.7 to 32.8 dB above the minimum threshold.

Acoustic Stimulation↗
PubMed1989

Distortion of spatial selectivity by pattern onset stimulation.

Spatial selectivity of pattern evoked potentials has been thought to provide evidence of lateral inhibition. However, spatial tuning functions may be distorted by pattern onset stimulation that is applied repeatedly to the same area of retina so an after-image is formed. This only applies at low spatial frequencies because of the randomizing effects of eye movements. Low-frequency attenuation may therefore be exaggerated. Pattern reversal stimulation has the opposite effect and this is reflected in the literature by fewer reports of bandpass functions. A new method has therefore been devised to provide the true spatial response function. The spatial phase is reversed after every two consecutive presentations. By combining this paradigm with a correction for the optical transfer function of the eye, the true neural response function is obtained. Ten subjects participated in this study to evaluate the distortion of spatial selectivity in the pattern electroretinogram. The new stimulus paradigm reduced the low spatial frequency attenuation to a barely significant level giving an almost flat amplitude response for the + ve and - ve transients of the pattern electroretinogram for check sizes from 222' to 7' angular subtense. However, correction for optical degradation produces bandpass curves, which closely correspond to those predicted from recent data on receptive fields of primate retinal ganglion cells.

Adult↗
PubMed1987

Backward masking of lateralized faces by noise, pattern, and spatial frequency.

Experiments 1 and 2 measured the critical interstimulus interval at which a face presented to the right or left visual field escaped a trailing noise, pattern, or spatial-frequency mask. The function relating target duration to critical ISI was multiplicative in the noise and spatial-frequency condition, but additive at longer durations in the pattern mask condition. An advantage of about 8 msec for the left visual field and 2 msec for the right field was found in the pattern and spatial-frequency masking condition, respectively. No consistent visual field differences were found in the noise mask condition. Taken together, these results suggest that hemispheric difference in face recognition are either absent or inconsistent at early, peripheral, energy-sensitive stages of processing, but emerge strongly at higher order central stages. The results also suggest that the left and right hemispheres are not differentially sensitive to the output of high- and low-spatial-frequency channels, respectively. If it is assumed that the central face processor is functionally localized to the right hemisphere, one can infer from these results that interhemispheric transmission time is not greater than 8 msec, and the output of sensory analysis and/or relational features are transferred across the interhemispheric commissures.

Adolescent↗
PubMed1978

Modification of the kitten's visual cortex by exposure to spatially periodic patterns.

Kittens were dark-reared except for exposure to three types of spatially periodic, vertically striped pattern: 1. single, widely spaced black bars; 2. wide areas of regular vertical grating separated by large blank patches; 3. a uniform, continuous grating with a spatial frequency of 0.5 c/deg. In each case there was a bias towards vertical in the distribution of preferred orientations of cells recorded in the visual cortex. The contrast sensitivity of individual neurones for gratings of different spatial frequencies was analysed quantitatively. In kittens exposed to a uniform grating of 0.5 c/deg, many cells were maximally sensitive close to 0.5 c/deg, as they are in normal cats. The occipital potential evoked by vertical gratings higher in frequency than 0.3 c/deg was consistently greater in amplitude than that for horizontal, and a vertical grating of 0.5 c/deg produced the maximum activity. These results are compared with those of Maffei and Fiorentini (1974); the differences between our results and theirs may be attributable to the degree of variability in spatial frequency and orientation during rearing, and to the duration of exposure.

Animals↗
PubMed2025

Single-cell-scale spatial transcriptome of the developing and adult mouse ovary.

Mammalian ovary development is essential for female fertility, involving the complex spatial patterning of diverse cell types to establish the finite reserve of ovarian follicles. While single-cell transcriptome analyses have provided important insights into the mechanisms driving specification and developmental trajectories of ovarian cells, they disrupt this crucial spatial context. To overcome this limitation, we used 10X Genomics Visium HD spatial transcriptomics to analyze the developing mouse ovary while maintaining its native cellular architecture. We captured all ovarian cell types at eight key fetal and postnatal timepoints, generating a near single cell resolution library of spatial gene expression across ovarian development. This comprehensive dataset allows analysis of dynamic transcriptional signatures associated with unique spatial patterning throughout development, including the establishment of cortex and medulla and assembly of ovarian follicles in each region. This dataset represents a fundamental resource for the investigation of regulatory mechanisms driving spatial patterning of the ovary and opens new avenues to explore the spatial determinants of female fertility and reproductive longevity.

Journal Article↗
PubMed1992

Homeotic genes have specific functional roles in the establishment of the Drosophila embryonic peripheral nervous system.

The Drosophila embryonic peripheral nervous system (PNS) contains segment-specific spatial patterns of sensory organs which derive from the ectoderm. Many studies have established that the homeotic genes of Drosophila control segment specific characteristics of the epidermis, and more recently these genes have also been shown to control gut morphogenesis through their expression in the visceral mesoderm (Tremml, G. and Bienz, M. (1989), EMBO J. 8, 2677-2685). We report here the roles of homeotic genes in establishing the spatial patterns of sensory organs in the embryonic PNS. The PNS was examined in embryos homozygous for mutations in the homeotic genes Sex combs reduced (Scr), Antennapedia (Antp), Ultrabithorax (Ubx), abdominal-A (abd-A) and Abdominal-B (Abd-B) with antibodies that label specific subsets of sensory organs. Our results suggest that the homeotic genes have specific roles in establishing the correct spatial patterns of sensory organs in their normal domains of expression. In addition, we also report the effects of ectopic expression of the homeotic genes labial (lab), Deformed (Dfd), Scr, Antp or Ubx on the normal development of sensory organs in the embryonic PNS. Interestingly, while previous studies have concluded that ectopic expression of the homeotic genes Dfd, Scr and Antp has no effect on the segmental identity of the abdominal segments, our results demonstrate that this is not true. We show that ectopic expression of these genes does result in the disruption of the developing PNS in the abdomen. Our results are suggestive of a role for the homeotic gene products in regulating genes which are necessary for generating sensory progenitor cells in the developing PNS.

Animals↗
PubMed1992

Configural effects constrain Fourier models of pattern discrimination.

Many models of spatial pattern discrimination assume that judgments are based on information directly available from mechanisms tuned to limited ranges of spatial frequency and orientation. We tested the validity of this assumption for spatial frequency, orientation, and contrast information in a series of complex pattern discrimination experiments. Observers discriminated between simple gratings, between gratings masked by components that differed widely in spatial frequency and/or orientation, and between patterns that presented two cues to discrimination, one in each frequency and/or orientation band. Component cues were combined either in rigid-object correspondence (e.g. both components were rotated clockwise in one pattern and counterclockwise in the other) or in opposition (e.g. in one pattern one component was rotated clockwise, the other counterclockwise; the direction of rotation was reversed for each component in the second pattern). The results demonstrate that information from tuned pathways is not always used directly in making spatial judgments, but in some cases is combined across wide regions of the Fourier domain prior to the discrimination decision. We find two distinct patterns of combination that appear to independently signal information about texture and edges. These findings provide a potential link between low-level, spatially tuned analyzers in the visual system and higher-level pattern processing mechanisms.

Adult↗
PubMed1991

Genetic population structure of Italy. I. Geographic patterns of gene frequencies.

The diversity of spatial patterns of 61 allele frequencies for 20 genetic systems (15 loci) in Italy is presented. Blood antigens, enzymes, and proteins were analyzed. The total number of data points over all systems and localities was 1119. We used homogeneity tests, one-dimensional and directional spatial correlograms, and SYMAP interpolated surfaces. The data matrices were reduced by clustering techniques to reveal the principal patterns. Only a few allele frequency surfaces are strongly correlated across loci. All systems but one (ADA) exhibit significant heterogeneity in allele frequencies among the localities. Significant spatial patterns are shown by 27 of the 61 surfaces. Only one pattern (cde; system 4.19) is clinal; another (PGM1) exhibits a pure isolation by distance pattern; the others show long-range differentiation in addition to the short-distance decline of autocorrelation expected under isolation by distance. There is a marked decline in overall genetic similarity with distance for most variables. The 27 spatially significant alleles in Italy are also significantly patterned in Europe, but in all but 2 cases the country-wide and continent-wide patterns differ. The Italian patterns are due to forces specific to Italy. Differential selection for alleles associated with malaria is still evident. Whereas short-range differentiation can with malaria is still evident. Whereas short-range differentiation can be explained by isolation by distance, long-range differentiation appears to be due to demographic changes in certain populations that may be maintained by physical and linguistic isolation.

Gene Frequency↗
PubMed2026

Spectral Transforms as a Tool to Optimize Digital Phenotyping in Biological Images.

Modern livestock breeding has mastered genotyping. Genome-wide association studies, genomic selection, and SNP arrays enable genetic merit prediction at lower cost. However, phenotyping remains the bottleneck, as manual measurement is slow, expensive, subjective, and unable to capture spatial or temporal trait organization. Digital phenotyping via artificial intelligence could resolve this, but deep learning requires thousands of labelled examples, impractical when phenotyping cost itself limits datasets to hundreds of individuals. This creates a paradox: AI could accelerate phenotyping but requires large numbers of samples to train the models. Here, we demonstrate that integrating computer vision with machine learning offers sample-efficient digital phenotyping using eggshell colour as a model system. Rather than learning features from scratch (deep learning), we engineer physically motivated features via Wavelet transforms that decompose images into multi-scale spatial components. Wavelet features captured 14.2 percentage points more variance (R2&#x2009;=&#x2009;0.976 vs. 0.834, p&#x2009;<&#x2009;0.001) than standard colorimetry, with 50% better sample efficiency (achieving at n&#x2009;=&#x2009;60 what colorimetry required n&#x2009;=&#x2009;120). Variance decomposition revealed 77% of discriminative capacity derives from spatial patterns (bands, spots, gradients) invisible to scalar averages. Additionally, we identified "cryptic phenotypes" (3.3%) where spatial patterns contradicted average colour, cases where colorimeters failed but Wavelets succeeded. The underlying principle-that spatial decomposition can recover organizational information lost by scalar averaging-may be applicable to other traits with spatial or temporal structure, such as marbling, dermatitis, or pigmentation rhythms, although whether comparable performance gains would be observed remains to be tested empirically. Hence, for breeding programs implementing genomic selection, computer vision-based digital phenotyping captures complex trait variation without massive training datasets, addressing the bottleneck that increasingly limits genetic progress as genotyping becomes trivial.

Wavelet transform↗