SEARCH · Search PubMed

Results for “Physical clustering”

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

SourceResearch connectionFrom yearThrough year

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

At least 37 records · Page 2Linked to original sources

PubMed1978

Comparison of the prevalence of hypertension in the rural and urban areas of Guilan Province, Northern Iran.

Blood pressure levels of three groups of people 35 years and older in the Guilan province, Northern Iran are compared. One group in the city of Bandar Pahlavi (550) another group in the coastal villages near the city (510) and the third in the mountain villages, less than 100 km far from the city (272). This study shows that in both sexes, both systolic and diastolic blood pressure are lowest in the mountain villages, highest in the city and intermediate in the coastal villages. The possible causes of the observed differences are discussed.

Adult↗

PubMed2026

Functional constipation in pregnancy and its association with dietary intake and physical activity: a cross-sectional study.

BACKGROUND: Functional constipation (FC) is a common complaint during pregnancy and has been reported to be associated with physical activity and dietary intake. However, previous studies have reported inconsistent findings. Therefore, this study aimed to determine the prevalence of FC and examine its association with physical activity and dietary intake among pregnant women. METHOD: In this cross-sectional study, 381 healthy pregnant women attending urban health centres in Tabriz, Iran, between January 2024 and February 2025, were selected using a multistage cluster sampling method. FC was diagnosed according to the Rome IV criteria. Data were collected through face-to-face interviews using the International Physical Activity Questionnaire (IPAQ) and the Food Frequency Questionnaire (FFQ). Multivariable Generalised Estimating Equations (GEE) analysis was performed to identify factors associated with FC. RESULTS: The overall prevalence of FC throughout pregnancy was 37%. In the first trimester, 41 out of 73 women (56%) had FC, while in the second trimester 53 out of 146 women (36%), and in the third trimester 47 out of 162 women (29%) were affected. Multivariate GEE indicated that both higher dietary fibre intake (aOR= 0.88, 95%CI 0.86-0.91, p < 0.001) and higher fluid intake (aOR= 0.59, 95%CI 0.52-0.67, p < 0.001) were associated with a reduced risk of FC. A normal BMI was associated with a lower risk of FC (aOR= 0.35, 95% CI 0.16-0.77, p = 0.009), whereas, secondary education was associated with a higher risk (aOR= 2.81, 95%CI 1.33-5.95, p = 0.007). Physical activity (aOR= 1.00; 95%CI 1.00 to 1.01; p = 0.168), and other demographic characteristics (p > 0.05) were not independently associated with FC after adjustment. CONCLUSION: FC is highly prevalent during pregnancy and may adversely affect women's quality of life. Higher dietary fibre and fluid intake were associated with lower odds of FC, highlighting the importance of healthy lifestyle behaviours during pregnancy. Prospective longitudinal studies are warranted to confirm these findings.

Humans↗

PubMed2020

PTSD is associated with increased DNA methylation across regions of HLA-DPB1 and SPATC1L.

Posttraumatic stress disorder (PTSD) is characterized by intrusive thoughts, avoidance, negative alterations in cognitions and mood, and arousal symptoms that adversely affect mental and physical health. Recent evidence links changes in DNA methylation of CpG cites to PTSD. Since clusters of proximal CpGs share similar methylation signatures, identification of PTSD-associated differentially methylated regions (DMRs) may elucidate the pathways defining differential risk and resilience of PTSD. Here we aimed to identify epigenetic differences associated with PTSD. DNA methylation data profiled from blood samples using the MethylationEPIC BeadChip were used to perform a DMR analysis in 187 PTSD cases and 367 trauma-exposed controls from the Grady Trauma Project (GTP). DMRs were assessed with R package bumphunter. We identified two regions that associate with PTSD after multiple test correction. These regions were in the gene body of HLA-DPB1 and in the promoter of SPATC1L. The DMR in HLA-DPB1 was associated with PTSD in an independent cohort. Both DMRs included CpGs whose methylation associated with nearby sequence variation (meQTL) and that associated with expression of their respective genes (eQTM). This study supports an emerging literature linking PTSD risk to genetic and epigenetic variation in the HLA region.

Cytoskeletal Proteins↗

PubMed2026

The Fragile Site Landscape of Induced Pluripotent Stem Cells: Hierarchy, Variability, Tissue Specificity, and Links to Culture-Acquired Rearrangements.

Induced pluripotent stem cells (iPSCs) are prone to genomic instability during prolonged culture, with recurrent chromosomal aberrations conferring selective advantages. Replication stress is a major driver of this instability, yet the repertoire of replication stress-sensitive loci in iPSCs remains largely unexplored. Here, we mapped aphidicolin-sensitive fragile sites (asFS) in three independent iPSC lines using classical cytogenetic break analysis combined with Monte Carlo simulation and MiDAS mapping directly on banded metaphase chromosomes. We identified 28 asFS, which segregated into a highly active Major cluster (8 sites, accounting for 59% of breaks among asFS) and a less active Minor cluster (20 sites). Five universal asFS (9p21, 6q25-26, 20p11-12, 10q22, Xq25) were present in all three lines, representing a fragility signature associated with the pluripotent state, with Xq25 shifting into the Major cluster after correction for X chromosome dosage. Minor asFS showed preferential co-localization with physical breakpoints or minimal overlapping regions of recurrent culture-acquired aberrations, including 20q11.21 (BCL2L1), 1q32 (MDM4), 8q24 (MYC), 17q21 (WNT3-WNT9B), and 18q21 (DCC/FRA18B). MiDAS mapping validated most asFS and revealed additional replication stress-sensitive loci in pericentromeric and subtelomeric regions that are difficult to score by conventional G-banding. Comparison with fragile site maps from other cell types revealed that the iPSC asFS repertoire is distinct in rank order and relative activity, characteristic of the pluripotent state. Collectively, our findings indicate that the asFS repertoire in iPSCs is hierarchically organized into a stable universal core and a variable peripheral component, and suggest that Minor asFS may contribute to, or be associated with, the genesis of culture-acquired rearrangements. This work provides a framework for understanding how replication stress and clonal selection shape the mutational landscape of pluripotent stem cells.

Induced Pluripotent Stem Cells↗

PubMed1977

Direct assignment of the cysteinyl, the slowly exchangeable, and the aromatic ring 1H nuclear magnetic resonances in clostridial-type ferredoxins.

We have directly assigned the 1H NMR corresponding to the cysteinyl protons, the slowly exchangeable protons, and the aromatic ring protons in the 1H NMR spectrum of Clostridium acidi-urici ferredoxin by isotopic labeling and 13C NMR decoupling techniques. We also show that the resonance pattern in the 8- to 20-ppm (from 2,2-dimethyl-2-sialapentanesulfonic acid) region of the 1H NMR spectra of oxidized Clostridium acidi-urici, Clostridium pasteurianum, Clostridium perfringens, and Peptococcus aerogenes ferredoxins are very similar, and we assign the resonances in this region by analogy with the spectrum of C. acidi-urici ferredoxin. The 1H NMR spectra of the beta protons of the cysteinyl residues of these ferredoxins differ, however, from the 1H NMR spectra of equivalent beta protons of the methylene carbon atoms bonded via a sulfur atom to [4Fe-4S] clusters in synthetic inorganic analogues. In the spectra of the synthetic compounds, the beta protons appear as a single resonance shifted 10 ppm from its unbonded reference position. In the spectra of oxidized clostridial ferredoxins, the cysteinyl beta protons appear as a series of at least eight resolved resonances with shifts that range from 6 to 14 ppm, relative to the free amino acid resonance position. This difference in the spectra of the protein and the synthetic compounds probably results from the fact that the equivalent beta protons of the synthetic compounds are not constrained and are free to rotate and thus assume the same average orientation with respect to the [4Fe-4S] cluster. The shift pattern in the 9- to 14-ppm region is identical in three different clostridial ferredoxins. This suggests that the molecular environments of the corresponding cysteinyl residues are identical. Significant differences in the resonance positions occur, however, in the 14- to 18-ppm region, suggesting that the physical environments of these cysteinyl residues differ. This may reflect differences in the orientation of the corresponding cysteinyl residues relative to the [4Fe-4S] clusters or differences in charge density at the cysteinyl beta protons or both. The slowly exchangeable protons were identified by comparing the 1H NMR spectra of ferredoxins reconstituted in H2O and 2H2O. The remaining resonances in the 8- to 20-ppm region were assigned to each of the 2 tyrosyl residues in C. acidi-urici ferredoxin. This was done by comparing the 1H NMR spectra of C. acidi-urici [(3',5'-2H2)Tyr]ferredoxin and C. acidi-urici [PHE2]ferredoxin with that of C. acidi-urici native ferredoxin.

Amino Acids↗

PubMed1975

Epidemiological studies in psychosomatic medicine.

The epidemiological triad of host, agent and environment used conceptually in infectious disease may serve as a model for psychosomatic disorders, despite the involvement of many more variables. There are major problems with diagnosis and measurement, however, and the term "psychosomatic" has several meanings. The two main senses are "specific" psychosomatic disorders and an ecological view of illness. The association between psychiatric and physical disorder has been examined in a variety of settings and the findings have suggested that there is a positive relationship. Despite considerable methodological and sampling difficulties in epidemiological research into psychosomatic illness, recent efforts have been made to overcome these. The results of ecological studies appear to be more consistent that those dealing with "specific" psychosomatic disorders and suggest that man has a general psychophysical propensity to disease. Although physical and mental illness do seem to be intimately linked, the reasons for "vulnerability" to illness and "clustering" of illness are obscure. The clarification of these areas appears to be the main task ahead for epidemiology in the field of psychosomatic medicine.

Epidemiologic Methods↗

PubMed1979

Structure of the malB region in Escherichia coli K12. I. Genetic map of the malK-lamB operon.

A series of deletions, Mu insertions and point mutations affecting the malK-lamB operon have been isolated. They were used to establish a deletion map of this operon, which could be divided in 27 intervals, with 16 in malK and 11 in lamB. One interesting feature of this map is the lack of randomness in the distribution of Mu insertions in the lamB gene; by using data published elsewhere on the physical length of the deletion intervals it can be concluded that about 25% of these Mu insertions are clustered in a segment representing 2 to 8% of the gene. This map is presently being used to study the biosynthesis, structure, and function of the lamB product, which is an outer membrane protein involved in the transport of maltose and maltodextrin, and which in addition constitutes the receptor for phage lambda.

Chromosome Mapping↗

PubMed1979

Self concept of the cleft lip and or palate child.

This investigation examined the relationship of the self-concept of children with cleft lip and/or palate to the self-concept of noncleft children. Thirty-four cleft lip and/or palate children between the ages of 11 and 13 were individually matched with thirty-four noncleft school children. Each child was given the Piers-Harris Children's Self Concept Scale. Children with clefts, regardless of sex, reported a significantly greater dissatisfaction with physical appearance. A significant interaction effect between sex and presence or absence of cleft was found on three cluster scores with cleft girls reporting greater unhappiness and dissatisfaction, less success in school, and more anxiety.

Adolescent↗

PubMed1979

Headaches--fact or fantasy?

Headaches are among the commonest symptoms encountered in active general practice. Much appears in the medical literature on this subject, most of it not applicable to everyday practice. A simple classification, a pattern of easy recognition, and a treatment plan for these chronic headaches are presented.

Chronic Disease↗

PubMed2026

Teacher- Versus Video-Delivered Classroom Activity Breaks and Student Physical Activity: The PAAC-3 Trial.

BACKGROUND: Classroom activity breaks may increase moderate-to-vigorous physical activity (MVPA); however, few studies have compared teacher and video-delivered approaches under real-world conditions. METHODS: In this cluster randomized trial, 11 elementary schools were assigned to teacher-delivered (PAAC-T; 5 schools, 192 students) or video-delivered (PAAC-V; 6 schools, 276 students) classroom activity breaks across one academic year. Teachers were trained to deliver two 10-min breaks daily. Intervention delivery was tracked via a web-based platform, and classroom MVPA was assessed using accelerometers at baseline and follow-up. RESULTS: Implementation fidelity was low and highly variable, but comparable between PAAC-T (42.3 ± 57.1 activity breaks/teacher/year) and PAAC-V (39.2 ± 33.9; p = 0.96), with teachers delivering ∼50% of the intended daily activity. Classroom MVPA increased significantly in both groups (PAAC-T: 9.8 ± 15.9; PAAC-V: 9.1 ± 15.3 min/day; p < 0.001), with no intervention arm-by-time interaction (p = 0.43). IMPLICATIONS FOR SCHOOL HEALTH POLICY, PRACTICE, AND EQUITY: Classroom physical activity breaks may increase student MVPA, but effectiveness in elementary schools appears to depend on implementation fidelity, administrative support, and equitable system-level infrastructure. CONCLUSIONS: Modest increases in classroom MVPA were observed across both delivery formats, although low and variable implementation fidelity limited conclusions regarding effectiveness and highlighted the need for stronger implementation supports. TRIAL REGISTRATION: NCT03493139.

Humans↗

PubMed1976

Binuclear copper clusters as active sites for oxidases.

Binuclear cupric ion clusters have been established in: human ceruloplasmin, hemocyanin, and mushroom tyrosinase. Substantial evidence makes it very probable that fungal laccase and zucchini ascorbate oxidase contain this cluster. Some evidence makes it possible that copper clusters function in the catalytic cycles of cytochrome oxidase (mammalian) and dopamine-beta-hydroxylase. These studies throw light on the criteria which must be employed to establish the existence of functional binuclear copper clusters in enzymes: (1) Stoichiometric Criteria: binding of O2 and CO with Cu/ligand = 2; redox titrations with n = 2; (2) Physical and Chemical Criteria: magnetic evidence of diminished paramagnetism of cupric centers, EPR evidence of broadened or absent absorptions, EPR evidence of magnetic dipolar interactions among cupric ions; absorption bands characteristic of Cu(II)-Cu(II) complexes; laser resonance raman scattering characteristic of peroxidic dioxygen in the oxyforms.

Animals↗

PubMed1977

Recombinant plasmid that carries part of the nitrogen fixation (nif) gene cluster of Klebsiella pneumoniae.

We have cloned fragments of the Klebsiella pneumoniae genome that carry part of the his operon and part of the nitrogen fixation (nif) gene cluster on the amplifiable plasmid pMB9. One particular plasmid, pCRA37, complements mutations in the hisD, nifB, and nifF loci. The physical map of pCRA37 as determined by restriction enzyme analysis correlates with the genetic map of the his-nif region as determined previously by phage P1-mediated cotransductional analysis.

Chromosome Mapping↗

PubMed2025

Inclusion of Physical-Chemical Water Quality Measurements Can Improve Associations between SARS-CoV-2 RNA Levels in Wastewater and COVID-19 Cases within Smaller Sewersheds.

Measurements of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in wastewater can be used to understand the prevalence of COVID-19 cases within a community. Environmental conditions inclusive of physical-chemical water quality characteristics are known to impact wastewater SARS-CoV-2 signals, but they are rarely measured within the sewer infrastructure in areas upstream of wastewater treatment plants (WWTPs). The objectives of this study were to report on measurements of environmental parameters [flow and physical-chemical water quality (water temperature, pH, specific conductivity, dissolved oxygen, and turbidity)] upstream of a WWTP and to evaluate whether the inclusion of these environmental parameters improves correlations between SARS-CoV-2 RNA levels in wastewater, and COVID-19 prevalence in the sewershed community. Measurements of environmental parameters and SARS-CoV-2 RNA in wastewater spanned different time scales (minutes, hours and weeks) and population scales (building, campus, community). For short time scales, water quality parameters did not improve correlations between SARS-CoV-2 in wastewater and COVID-19 prevalence due to high variability of water quality and flows within the sewer system. When averaging data over weekly time scales, regressions showed that inclusion of pH improved correlations between RNA and COVID-19 prevalence. At the cluster scale, for the entire data set, the root mean square error decreased from 6.9 cases per week to 6.5 cases per week. At the community scale benefits were observed only for the delta wave with a decrease in root mean square error from 539 cases per week to 430 cases per week. The inclusion of pH improved correlations between wastewater SARS-CoV-2 and COVID-19 prevalence more frequently when evaluating the cluster sewershed scale (populations of a few thousand) in comparison to the community scale (populations of several 100,000). Given the simplicity of measuring pH and other physical-chemical water quality parameters, their inclusion should be considered as part of wastewater-based epidemiology programs.

COVID-19↗

PubMed2026

Integrative modeling of the genome structure and dynamics in fission yeast.

Genome organization in the nucleus is highly structured and dynamic. Recent advances in genomic technology have enabled the measurement of genome-wide architecture and locus-specific motion, yielding contact maps and live-cell trajectories. However, these outcomes are derived from different modalities and are not directly comparable, with their quantitative integration being a key challenge. Here we establish a genome-wide live-cell imaging platform in fission yeast Schizosaccharomyces pombe, tracking 131 chromosomal loci, along with the spindle pole body (SPB) and nucleolus, to construct a quantitative map of locus dynamics. By integrating these dynamics with contact data through polymer modeling of Hi-C data, we build a physics-based "digital twin" of the S. pombe genome consistent with the spatiotemporal dynamics of interphase chromatin. We validate it against genome-wide mobility patterns and known architectural features, including centromere and telomere clustering. The model also identifies distinct dynamical regimes: centromere- and telomere-proximal loci relax within [Formula: see text]150 s, whereas the remaining loci relax within [Formula: see text]70 s. We measure semiperiodic dynamics of SPB motion, including a characteristic peak near 225 s and [Formula: see text] fluctuations. We use the model with SPB-directed forcing to show how these low-frequency components propagate through the genome to drive genome-wide chromatin displacements. Together, this predictive physics-based modeling framework integrates genome structure and dynamics to reveal how nuclear mechanical driving forces shape chromosome motion, linking mechanically driven chromatin responses to genome maintenance and regulation.

Schizosaccharomyces↗

PubMed1979

Association of centrioles with clusters of apical vesicles in mitotic thyroid epithelial cells. Are centrioles involved in directing secretion?

The ultrastructure of thyroid epithelial cells in mitosis has been investigated. A spatial association is described between clusters of apical vesicles (believed to contain thyroglobulin destined for secretion into the follicular lumen) and centrioles, in late prophase and late telophase cells. Quantitative techniques demonstrate the statistical significance of this association and suggest that it is not related to proximity of the Golgi apparatus or to the location of the centriole in the cell, which changes considerably during these phases of mitosis. The physical basis for this association remains uncertain, but microtubules emanating from the pericentriolar area may be involved. In interphase cells, centrioles are located very close to the follicular lumen, where the majority of apical vesicles are also found. The association of centrioles with clusters of apical vesicles also in mitotic cells suggests that in interphase cells the apically located centrioles may serve as a focus for apical vesicles, helping to direct these secretory vesicles toward the follicular lumen and to maintain cellular polarization. Previous studies demonstrating that centrioles can act as microtubule organizing centers in interphase cells and studies linking microtubules and secretion also tend to support this hypothesis.

Animals↗

PubMed1979

Lateral translational diffusion of cytochrome c oxidase in the mitochondrial energy-transducing membrane.

The degree of freedom for lateral translational diffusion by cytochrome c oxidase and other integral proteins in the energy-transducing membrane of the mitochondrion was determined by combining the use of an immunoglobulin probe monospecific for the oxidase with thermotropic lipid phase transitions. Lateral mobility of the oxidase was monitored by observing the distribution of the immunoglobulin probe on the membrane surface by deep-etch electron microscopy and by observing the distribution of intramembrane particles (integral proteins) in the hydrophobic interior of the membrane by freeze-fracture electron microscopy. Incubation of the membrane with the immunoglobulin resulted in a time-dependent clustering of predominantly large intramembrane particles. Low temperature-induced lipid phase transitions resulted in the close packing of all intramembrane particles and cytochrome c oxidase by lateral exclusion from domains of gel-state bilayer lipid and was completely reversible. However, when cytochrome c oxidase was crosslinked through an immunoglobulin lattice prior to returning the membrane to above the lipid phase transition temperature, small intramembrane particles rerandomized while the large oxidase-related particles remained clustered. These observations reveal that cytochrome c oxidase can diffuse laterally in the energy-transducing membrane, either independently of all other integral proteins or in physical union with one or more other integral proteins. In addition, many other as yet unidentified smaller integral proteins can diffuse independently of the oxidase.

Animals↗

PubMed1978

Particle segregation in chromaffin granule membranes by forced physical contact.

Bovine chromaffin granules were exposed to different isotonic non-ionic and ionic solutions (sucrose; Ca2+- and Mg2+-free phosphate-buffered saline; Tris-HCl + NaCl; Ca2+- and Mg2+-free phosphate-buffered saline + sucrose; Tris-HCl + sucrose) at pH 7 and then frozen either in suspension or as firm pellets. Freezing was performed without prefixation or antifreeze treatments either by 'standard' techniques (approx. 1 mm3 suspended or pelleted material on gold specimen supports dipped into liquid Freon) or with increased cooling rates by spraying suspensions into liquid propane ('spray-freezing'). Regardless of the freezing method, membrane-intercalated particles were always randomly distributed when chromaffin granules were frozen in suspension. In contrast, forced physical contact between granules produced by centrifugation (12000 X g, 25 min) provoked dispersal of membrane-intercalated particles, but only in the presence of ions. Sucrose or EDTA in an ionic environment had no inhibitory effect. The following conclusions are derived: (1) Even below the reported phase transition region particle clustering is possible. (2) Chromaffin granule membranes are not liable to thermotropic segregation of membrane-intercalated particles. (3) Although the low freezing rates of 'standard' freezing techniques produce large-scale segregation artefacts (by which suspended chromaffin granules are pushed together within the segregated solute) this does not result in intramembraneous particle segregation. (4) Forced physical contact produces a Ca2+-independent particle segregation, but only when repulsive electrostatic forces of membrane components are partially screened in an ionic environment. (5) This does not invalidate results obtained by others, showing Ca2+-mediated chromaffin granules agglomeration and segregation of membrane-intercalated particles, but it might indicate the occurrence of another, not directly Ca2+-dependent particle segregation mechanism in a prefusional stage of close membrane-to-membrane contact during exocytosis.

Animals↗

PubMed1976

Mapping of promoter sites on the genome of bacteriophage M13.

With the aid of transcription studies on restriction fragments of bacteriophage M13 DNA it has been demonstrated that at least eight promoter sites are located on the M13 genome. Five of these promoters initiate the synthesis of RNA chains which contain at their 5'-terminal end pppG (G promoters), while the other three promoters initiate RNA chains which start exclusively with pppA (A promoters). The positions of these promoter sites on the physical map are: 0.82 (G0.82), 0.88 (G0.88), 0.94 (G0.94), 0.01 (G0.01), 0.08 (G0.08), 0.36 (A0.36), 0.51 (A0.51) and 0.56 (A0.56). The G promoters were found to be clustered within a distance of one-third of the genome length from the central termination site for transcription (map position 0.77). The A promoters, however, were found at greater distances from this termination signal. Based upon the incorporation of [gamma-32P]ATP or [gamma-32P]GTP, the capacity of these promoters to initiate the synthesis of RNA chains varies. The strongest G promoters are G0.82, G0.94 and G0.08 and the strongest A promoter is A0.36. As judged from their position on the genetic map, it is postulated that two promoters, namely G0.94 and G0.01, are located within gene II. The other promoters are most probably located immediately in front of the gene VIII/VII boundary (G0.82), and immediately in front of gene V (G0.88), gene II (G0.08), gene IV (A0.36), gene I (A0.51) and gene VI (A0.56). No evidence has been obtained so far for the existence of a promoter immediately in front of gene III.

Base Sequence↗