SEARCH · PubMed Health

Results for “spatial spread”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 19 recordsLinked to original sources

PubMed2026

Reconstructing the early spatial spread of pandemic respiratory viruses in the United States.

Understanding the geographic spread of emerging respiratory viruses is critical for pandemic preparedness, yet the early spatiotemporal dynamics of the 2009 H1N1 pandemic influenza and severe acute respiratory syndrome coronavirus 2 in the United States remain unclear. While mobility and genomic data have revealed important aspects of pandemic spatial spread, several key questions remain: Did the two pandemics follow similar spatial transmission routes? How rapidly did they spread across the United States? What role did stochastic processes play in early spatial transmission? To address these questions, we integrated high-resolution disease data with a robust, data-efficient inference framework combining air travel, commuting flows, and pathogen superspreading potentials to reconstruct their spatial spread across US metropolitan areas. The two pandemics exhibited distinct transmission pathways across locations; however, both pandemics established local circulation in most metropolitan areas within weeks, driven by several shared transmission hubs. Early spatial spread was more strongly associated with air travel than with commuting, though stochastic dynamics introduced substantial uncertainty in transmission routes, creating challenges for timely detection and control. Simulations indicate that broad wastewater surveillance coverage beyond top transmission hubs coupled with effective infection control may slow initial spatial expansion. Our findings highlight the rapid, stochastic spread of pandemic respiratory pathogens and the difficulties of early outbreak containment.

Humans↗

PubMed1979

The cells of origin of the commissural afferents to the area dentata in the mouse.

The hippocampal commissural projection to the area dentata of the mouse was studied using the retrograde horseradish peroxidase (HRP) technique. Small volumes of HRP injected into the molecular layer of the fascia dentata or various subareas of regio inferior of the hippocampus (fields CA3a-c) resulted inlabeled perikarya in the contralateral hippocampus and area dentata. The commissural projection to the fascia dentata was observed to originate exclusively from cells within the hilus fasciae dentatae (CA4) of the contralateral area dentata. There was evidence of a considerable spread of commissural innervation along the septotemporal axis preferentially in the septal direction, confirming earlier observations. In contrast to the septotemporal spread, a sharp homotopic spatial organization was found in the mediolateral direction. For example, injections into the lateral portion of field CA3 (CA3a) resulted in HRP-positive cell bodies only in the contralateral field CA3a. When injections were made which apparently labeled all of the commissural fibers, the HRP reaction product was found in neurons both in the entire regio inferior and as far as the innermost point of the hilus fasciae dentatae; the majority of labeled cells were located in hippocampal subfield CA3c. No labeled cells were observed beyond the tip of the mossy fibers in regio superior.

Afferent Pathways↗

PubMed1979

Electrical coupling between cones in turtle retina.

1. The electrical coupling between cones of known spectral sensitivity in the peripheral part of the turtle's retina was studied by passing current through a micro-electrode inserted into one cone and recording with a second micro-electrode inserted into a neighbouring cone. 2. Spatial sensitivity profiles were determined by recording flash responses to a long narrow strip of light which was moved across the impaled cones in orthogonal directions. These measurements gave both the length constant lambda of electrical spread in the cone network and the separation of the two cones. 3. The cone separation determined from the spatial profiles agreed closely with that measured directly by injecting a fluorescent dye into two cones. 4. The length constant lambda varied from 18 to 39 micron with a mean of 25 micron for red-sensitive cones and 26 micron for green-sensitive cones. 5. The majority of cone pairs studied were electrically coupled provided they had the same spectral sensitivity and were separated by less than 60 micron: thirty-two out of thirty-six red-red pairs, two out of two green-green pairs, none out of eight red-green pairs: no blue cones were observed. 6. The strength of electrical coupling was expressed as a mutual resistance defined as the voltage in one cell divided by the current flowing into the other. Mutual resistances decreased from a maximum value of about 30 M omega at separations close to zero to 0.2 M omega, the lower limit of detectable coupling at separations of about 60 micron. Mutual resistances were always positive and were independent of which cell was directly polarized. The coupling seemed to be ohmic and any rectification or non-linearity probably arose in the cone membranes rather than in the coupling resistances. 7. The results were analysed in terms of the Lamb & Simon (1977) theories of square and hexagonal lattices, which approximate to the continuous sheet model except in the case of the cone to which current is applied. 8. The total membrane resistance of a single cone was estimated as 100--300 M omega and the connecting resistances as 100 M omega for a square array and 170 M omega for a hexagonal array. The input resistance of a cone in the network was 25--50 M omega. Lower values were often obtained but may be due to injury by the micro-electrodes. 9. The time constant of an isolated cone was estimated as about 20 msec and the capacity as about 100 pF. 10. Discrepancies between experimental findings and theoretical predictions of the hexagonal or square array models were tentatively attributed to an overestimate of lambda resulting from light scattering.

Animals↗

PubMed2025

Incorporating Epidemiological Data into the Genomic Analysis of Partially Sampled Infectious Disease Outbreaks.

Pathogen genomic data are increasingly being used to investigate transmission dynamics in infectious disease outbreaks. Combining genomic data with epidemiological data should substantially increase our understanding of outbreaks, but this is highly challenging when the outbreak under study is only partially sampled, so that both genomic and epidemiological data are missing for intermediate links in the transmission chains. Here, we present a new dynamic programming algorithm to perform this task efficiently. We implement this methodology into the well-established TransPhylo framework to reconstruct partially sampled outbreaks using a combination of genomic and epidemiological data. We use simulated datasets to show that including epidemiological data can improve the accuracy of the inferred transmission links compared with inference based on genomic data only. This also allows us to estimate parameters specific to the epidemiological data (such as transmission rates between particular groups), which would otherwise not be possible. We then apply these methods to two real-world examples. First, we use genomic data from an outbreak of tuberculosis in Argentina, for which data was also available on the HIV status of sampled individuals, in order to investigate the role of HIV coinfection in the spread of this tuberculosis outbreak. Second, we use genomic and geographical data from the 2003 epidemic of avian influenza H7N7 in the Netherlands to reconstruct its spatial epidemiology. In both cases, we show that incorporating epidemiological data into the genomic analysis allows us to investigate the role of epidemiological properties in the spread of infectious diseases.

Humans↗

PubMed1977

[Spatial deployments of morphogenetic movements as elements of the oral field in anuran amphibians. I. Structurally stable morphogenetic movements].

The movements of cells in the oral field of anuran embryos were followed by means of orto- and heterotopic transplantations of the ectoderm fragments. To mark individual ectoderm regions, the embryos were used which differed from each other by colour. The cells polarize along the apical-basal layer axis and the polarization spreads along the layer as a waver embracing consecutively new and new cells. The waves of morphogenetic rearrangements from the spatial deploiments of morphogenetic movement, i. e. the transition between the local morphologies of the layer which replace one another in time is swept continuously in space. The presence of spatial sweep is the necessary condition for the structural stability of morphogenetic movements.

Amphibians↗

PubMed2026

Fine-Scale Landscape Genomics Show Asymmetric Patterns of Gene Flow for the Invasive Mosquito Aedes albopictus.

Mosquito-borne viruses like dengue, Zika, and chikungunya pose increasing health risks in the United States due to the expanding range of Aedes albopictus, a highly invasive mosquito species that now has a global distribution. Aedes albopictus thrive in artificial containers associated with anthropogenic land use, allowing populations to reach high numbers in urban and suburban environments. While the global spread of Ae. albopictus has been well characterized, the effects of heterogeneous urban landscapes on dispersal and gene flow at fine spatial scales remain unclear. This study analyzed the genetic connectivity of Aedes albopictus populations collected in Wake County, North Carolina in 2018. We used single nucleotide polymorphisms (SNP) data from double-digest restriction-enzyme associated DNA sequencing (ddRADseq) and examined genetic connectivity through principal component analysis (PCA) and genetic network analysis. We then evaluated migration and source-sink dynamics using a Bayesian approach for SNP data (BA3-SNP). We found little evidence of genetic clustering or isolated populations of Ae. albopictus in Wake County, suggesting high gene flow between sites. Migration analysis demonstrated asymmetric gene flow from rural to urban regions within Wake County, with greater gene flow occurring between and within urban regions. These findings suggest that the pattern of gene flow of Ae. albopictus populations within local metropolitan areas may involve urban city centers serving as genetic sinks and surrounding suburban and rural regions serving as sources. This study highlights how heterogeneous landscapes shape mosquito population connectivity and migration at fine spatial scales, which is critical for informing vector control and public health intervention strategies.

Aedes albopictus↗

PubMed2026

Quantitative Fluorescence Imaging of Alphavirus Infection for Antiviral Screenings.

Fluorescence microscopy offers a highly sensitive and versatile approach for investigating alphavirus infection at the cellular level. By combining fluorescently labeled viruses with quantitative image analysis, this method enables detailed spatial and temporal characterization of infection dynamics, including the detection of subtle differences in replication kinetics and cell-to-cell spread. A central aim of this protocol is its application in antiviral screening assays. Image-based quantification of fluorescence intensity provides a robust and reproducible means to assess the efficacy of antiviral compounds, allowing early and sensitive detection of inhibitory effects in infected cells. This facilitates the identification of promising antiviral hits and supports the evaluation of dose-dependent responses. The approach is also well-suited for comparative studies of different alphavirus strains or mutants, as variations in replication behavior and dissemination patterns become readily apparent. Its flexibility, compatibility with multiple cell lines, and straightforward integration into automated imaging platforms makes the method scalable and suitable for high-throughput screening campaigns. Overall, this protocol advances the discovery and evaluation of antiviral strategies. Given that several alphaviruses cause significant human and veterinary diseases, lack approved antiviral therapies, and continue to expand geographically with emerging outbreaks, the identification of novel antivirals remains an urgent priority. Therefore, this fluorescence-based workflow represents a valuable and timely contribution to modern alphavirus research.

Antiviral Agents↗

PubMed2026

Genomic signatures of adaptation across a landscape of crickets following the introduction of a parasitoid fly.

Novel species interactions provide an opportunity to assess the earliest stages of genetic adaptation. We combined population genomics and field selection surveys to explore the genomic and geographic landscape of adaptation in small, fragmented Hawaiian cricket populations, which are parasitized by larvae of an introduced fly that targets singing males. Multiple protective male-silencing cricket morphs have recently spread under this novel selection pressure, despite song's important roles in mate attraction. We find evidence of sharp declines in cricket effective population sizes following the fly's introduction and identify regions under spatially varying selection mediated by infestation risk, which are linked to an adaptive morph and other genes implicating in resisting infestation. Despite repeated bottlenecks, genetic variation is dominated by structural variant polymorphisms seemingly maintained under balancing selection. Our study illustrates pervasive consequences of abrupt changes in selection on small populations. Fly-mediated selection remains strong despite the spread of adaptive male-silencing phenotypes, which also reduce male fitness in the context of mate attraction.

Animals↗

PubMed1977

[Structure of the morphogenetic movements of gastrulation in Anura. II. The elementary morphogenetic processes].

The clinostate rotation causes a wide range of gastrulation abnormalities in the Anura. A special investigation has shown that all gastrulation variants may be represented as various spatial-temporal compositions of the same morphogenetic processes isolated by means of formal experimental procedure. These processes are structurally stable rearrangements of tissue morphology and are spread in the tissue as a wave embracing more and more cells. The change of one local morphology for another may proceed either in the form of "shock wave", a moving distinct border between the cells already switched and not yet switched to the new automorphous movement, or in the form of "deployment" when the transition from one local morphology to another is continuously deployed in space.

Amphibians↗

PubMedDate not supplied

Cerebral blood flow in the monkey after focal cryogenic injury.

A focal cryogenic lesion was made in the left superior frontal gyrus of the anesthetized macaque brain. Cerebral blood flow (CBF) was determined by the hydrogen clearance technique before and during the 4 hours following trauma. Local CBF in tissue adjacent to the lesion increased in the first half hour after the lesion was made and then decreased during the ensuing 3 1/2 hours. Local CBF in the contralateral superior frontal gyrus, as well as total CBF and oxygen consumption, were unchanged by cryogenic trauma. The spread of vasogenic edema into uninjured tissue probably accounts for the observed decrease in local CBF. This experimental model may assist in discovering therapy to alter favorably the spatial and temporal profile of pathologic CBF changes in tissue surrounding an acute lesion of the brain.

Animals↗

PubMed1979

Polarized infrared spectroscopy of oriented purple membrane.

Polarized Fourier transform infrared spectroscopy has been used to study the structure of purple membrane from Halobacterium halobium. Membranes were oriented by drying a suspension of membrane fragments onto Irtran-4 slides. Dichroism measurements of the amide I, II and A peaks were used to find the average spatial orientation of the bacteriorhodopsin alpha-helices. By deriving a function that relates the observed dichroism to the orientational order parameters for the peptide groups, helical axis distribution, and mosaic spread of the membranes, the average orientation of the alpha-helices was found to lie in a range of less than 26 degrees away from the membrane normal, agreeing with electron microscopic measurements. The frequency of the amide I and A peaks is at least 10 cm-1 higher than values found for most alpha-helical polypeptides and proteins. This may indicate that bacteriorhodopsin contains distorted alpha-helical conformations.

Bacteriorhodopsins↗

PubMed1976

Temporo-spatial propagation of epileptoform after-discharges in the isolated cat suprasylvian gyrus.

1. Epileptiform after-discharges (EADSs) induced by electrical stimulation of the isolated suprasylvian gyrus were studied in cats with chronically implanted electrodes. 2. In a given region and at a certain time after stimulation, the following events took place: (a) a slow radial spread of the zone of maximal depolarization, from the cortical surface downward, as evidenced by a laminar study; (b) a massive cellular discharge preceded by a period during which few unit activities were detected, followed by bursts of spike activity timed with the surface-positive waves of the ECoG; (c) a surface-negative DC shift with maximal amplitude around 1000 mum below the surface; (d) the occurrence of a synchronizing focus from which the paraoxysmal waves propagated to the whole gyrus. 3. All these phenomena spread across the surface of the gyrus with a velocity (7-20 mm/min) similar to that of focal seizures in man.

Action Potentials↗

PubMed1977

Automatic measurement of sister chromatid exchange frequency.

An automatic system for detecting and counting sister chromatid exchanges in human chromosomes has been developed. Metaphase chromosomes from lymphocytes which had incorporated 5-bromodeoxyuridine for two replication cycles were treated with the dye 33258 Hoechst and photodegraded so that the sister chromatids exhibited differential Giemsa staining. A computer-controlled television-microscope system was used to acquire digitized metaphase spread images by direct scanning of microscope slides. Individual objects in the images were identified by a thresholding procedure. The probability that each object was a single, separate chromosome was estimated from size and shape measurements. An analysis of the spatial relationships of the dark-chromatid regions of each object yielded a set of possible exchange locations and estimated probabilities that such locations corresponded to sister chromatid exchanges. A normalized estimate of the sister chromatid exchange frequency was obtained by summing the joint probabilities that a location contained an exchange within a single, separate chromosome over the set of chromosomes from one or more cells and dividing by the expected value of the total chromosome area analyzed. Comparison with manual scoring of exchanges showed satisfactory agreement up to levels of approximately 30 sister chromatid exchanges/cell, or slightly more than twice control levels. The processing time for this automated sister chromatid exchange detection system was comparable to that of manual scoring.

Autoanalysis↗

PubMed1977

Visualization of centriole-bodies using silver stain.

Duplicate staining of human metaphase chromosomes, first with Giemsa followed by silver, revealed the presence of two small silver-stained bodies not seen in the Giemsa stained metaphases. Similar bodies were subsequently found in the metaphases of several animal groups. The size, structure, spatial relationships to the nucleus, behavior throughout the cell cycle, and apparent universal presence of these bodies suggest that they are either centrioles or associated centriolar structures. These centriole-bodies can be seen throughout the cell cycle, even in hypotonically spread C-metaphase chromosome plates. The silver stain procedure allows enough resolution to distinguish parent and daughter centriole-bodies at interphase, thus permitting visualization of the replication, maturation and separation stages of these bodies with the light microscope.

Animals↗

PubMed2026

Structure-resolved virus-host interactomics by cross-linking mass spectrometry.

Viruses depend on host protein networks to replicate, assemble progeny, and spread between cells and organisms. Defining these virus-host protein interactions is challenging because they are highly dependent on infection stage, cell type, species, and because mechanistic interpretation requires information about structural interfaces and conformational states. Cross-linking mass spectrometry (XL-MS) addresses these challenges by adding a spatial and structural dimension to virus-host interactomics in native systems. In this review, we discuss how XL-MS has advanced from targeted analysis of viral protein complexes to structure-resolved mapping of virion architecture and infected-cell virus-host interactomes. We highlight how XL-MS complements AP-MS, cryo-EM/cryo-ET, quantitative proteomics, genetic perturbation, and structure prediction to connect physical proximity with molecular mechanisms. Finally, we discuss current limitations in sensitivity, chemical coverage, temporal resolution, and model interpretation, and outline how future quantitative and integrative XL-MS workflows may enable systems-level structural virology.

Mass Spectrometry↗

PubMed1977

Molecular orbital studies on the mechanism of drug-receptor interaction. 2. beta-Adrenergic drugs. An approach to explain the role of the aromatic moiety.

The role of the aromatic moiety of beta-adrenergic drugs in the interaction with the receptor was investigated using the quantum mechanical ab initio SCF-MO-LCAO method. The structure-activity relationship was essentially discussed by analyzing the electrostatic molecular potential of three compounds which constitute meaningful portions of isoproterenol, INPEA, and doberol, the first drug having a stimulating activity and the others a blocking one. The results obtained point out the different roles played in the drug-receptor interaction by the various regions of the drugs and they also show that the aromatic moiety influences both the affinity and the intrinsic activity of the drugs. Indeed, the spatial correspondence among zones with negative potentials, which are localized on the phenyl substitutents of isoproterenol and INPEA and on the phenyl ring of doberol, could contribute to the affinity. On the other hand, the intrinsic activity of isoproterenol might be associated both with the proton-donor tendency of one phenolic OH group and with the wide zone of negative potential which spreads on a large part of the aromati moiety.

Ethanolamines↗

PubMed2026

Evolutionary history of Jamestown Canyon virus reveals complex multi-vector ecology.

Jamestown Canyon virus (JCV) is a historically understudied mosquito-borne virus of increasing concern in North America. We generated 658 whole-genome JCV sequences from northeast United States, including 84% (500/597) of all JCV-positive mosquitoes detected in Connecticut from 1997 to 2022. Then, we applied phylodynamic methods to demonstrate how mosquito phenology structures the maintenance and evolution of JCV. Our phylogenetic analyses estimate that JCV was introduced in the Northeast by at least the early 1700s, and the primary introductions of lineages A and B into Connecticut occurred during the mid-1800s to mid-1900s. Further, we estimate that JCV evolves at a rate of ∼3 × 10-5 substitutions per site per year (s/s/y), making it one of the slowest-evolving known RNA viruses, because the virus spends ∼10 months per year in evolutionary stasis while overwintering in mosquito eggs. To investigate ecological drivers of JCV spread in Connecticut, we paired discrete trait and continuous phylogeographic reconstructions with mosquito surveillance data. We estimate that JCV has a low diffusion rate of ∼30-60 km2/year, which is more similar to slow-moving tick-borne viruses than to other mosquito-borne viruses. We found that univoltine Aedes mosquitoes were likely to maintain the virus across years through overwintering in eggs, accounting for its slow evolution and dispersal, while multivoltine mosquitoes contributed to periodic bursts of spatial diffusion and amplification within seasons. We demonstrate the utility of dense sequencing and phylodynamics to disentangle complex transmission cycles, offering a framework for rapidly advancing our evolutionary and ecological knowledge of understudied viruses.

Animals↗

PubMed1977

[Spatial deployments of morphogenetic movements as elements of the oral field in anuran amphibians. II. The structure of the oral field].

The structure of morphogenetic movements in the oral field of Anura was studied. The movement of any region of the oral field depends on several "elementary waves" of morphogenetic rearrangements, each of them being swept in space along the same cell layer. The waves of morphological rearrangements of cells from different layers are coupled with each other in a stable manner. The cells of the given layer are involved in their morphogenetic movements consecutively, whereas the morphogenetic movements of cells in the interrelated layers are developed in parallel. The waves of morphological rearrangements are those of contact polarization of the cells and, under certain conditions, are spread within several minutes.

Amphibians↗