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At least 811 records · Page 45Linked to original sources
PubMed2005

A consistent relationship between local white matter architecture and functional specialisation in medial frontal cortex.

Functionally significant landmarks in the brain do not necessarily align with local sulcal and gyral architecture in a manner that is consistent across individuals. However, the functional specialisation underlying these landmarks is strongly constrained by the connectional architecture of the region. Here, we explore this relationship in the supplementary motor area (SMA) and pre-SMA in the medial frontal cortex of the human brain. Using diffusion tensor, conventional and functional MR imaging, we find that the location of the functional boundary between SMA and preSMA is more consistent with respect to specific features of the local white matter as it approaches neocortex than with respect to the local gyral and sulcal anatomy in the region.

Adult↗
PubMed2003

Architectural differences in the bony pelvis of women with and without pelvic floor disorders.

OBJECTIVE: To investigate the hypothesis that the architecture of the bony pelvis differs between women with and without pelvic floor disorders. METHODS: We designed a case-control study of women who had undergone magnetic resonance imaging (MRI) of the pelvis at our institution. Records were reviewed to identify women with and without pelvic floor disorders (urinary or anal incontinence, other symptoms of urinary tract dysfunction, or pelvic organ prolapse). Pelvimetry techniques were standardized. Relevant measures included transverse diameter of the inlet, angle of the pubic arch, intertuberous diameter, interspinous diameter, sacrococcygeal length, depth of sacral curvature, anteroposterior conjugate, obstetrical conjugate, and anteroposterior outlet. Multiple logistic regression analysis was used to identify women with pelvic floor disorders as a function of their pelvic dimensions, controlling for potentially confounding variables. RESULTS: Subjects included 59 women with pelvic floor disorders and 39 women without pelvic floor disorders. Women with pelvic floor disorders had a wider transverse inlet, wider intertuberous diameter, wider interspinous diameter, greater sacrococcygeal length, deeper sacral curvature, and narrower anteroposterior outlet. When controlling for the confounding effects of age, race, and parity, we found that a wider transverse inlet (odds ratio 3.425) and a shorter obstetrical conjugate (odds ratio 0.233) were significantly associated with pelvic floor disorders. CONCLUSION: A wide transverse inlet and narrow obstetrical conjugate are associated with pelvic floor disorders. We speculate that these features of bony pelvic architecture may predispose the patient to neuromuscular and connective tissue injuries, leading to the development of pelvic floor disorders.

Adult↗
PubMed2005

Variations in the architecture and development of the vertebrate optic chiasm.

At the vertebrate optic chiasm there is major change in fibre order and, in many animals, a separation of fibres destined for different hemispheres of the brain. However, the structure of this region is not uniform among all species but rather shows marked variations both in terms of its gross architecture and the pathways taken by different fibres. There also are striking differences in the developmental mechanisms sculpting this region even between closely related animals. In spite of this, recent studies have provided strong evidence for a remarkable degree of conservation in the molecular nature of the guidance signals and regulatory genes driving chiasmatic development. Here differences and similarities in chiasmatic organisation and development between separate groups of animals will be reviewed. While it may not be possible to ascribe a single set of factors that are universal components of the vertebrate chiasm, there are both strikingly similar elements as well as diverse features to the development, organisation and architecture of this region. This review aims to highlight key issues in the organisation and development of the vertebrate optic chiasm with a focus on comparing and contrasting the data that has been gleaned to date from different vertebrate groups.

Animals↗
PubMed2004

Architectural remodelling in lungs of rabbits induced by type V collagen immunization: a preliminary morphologic model to study diffuse connective tissue diseases.

The pathogenesis of diffuse connective tissue diseases (DCTD) is still unknown and has been extensively studied regarding its autoimmunity aspects related to extracellular matrix (ECM) remodelling, with an emphasis on the collagens at the inflammatory site. The present paper describes the pulmonary architectural and repair/remodelling responses to injury after immunization of rabbits with human type V collagen. The animal model consisted of rabbits immunized with collagen mixed with Freund's adjuvant and sacrificed 7, 15, 30, 75, and 120 days after the first of four doses of antigen. Pulmonary architecture remodelling response was evaluated by histology, morphometry, and the immunofluorescence method, according to compartments of reference (parenchyma and interstitium) and injury: 1 inflammation (polymorphonuclear and mononuclear cells); 2-repair (fibrosis) and 3-ECM remodelling (collagen system). The results showed an intense inflammatory involvement of the pulmonary vascular and bronchiolar parenchyma, characterized by increased wall thickness in small arteries, infiltrations by pseudoeosinophils, and mononuclear cells. Progressive remodelling of the pulmonary ECM was characterized by collagen deposition in the septal and bronchovascular interstitium, especially in rabbits sacrifices at 75 and 120 days. The ECM remodelling process was not reproduced when rabbits were inoculated with collagen types I and III. We conclude that the model reproduces morphologic changes similar to those observed in many DCTD, encouraging realization of other experiments to gain a better understanding of the pathogenesis of these diseases.

Animals↗
PubMed2006

The building blocks and motifs of RNA architecture.

RNA motifs can be defined broadly as recurrent structural elements containing multiple intramolecular RNA-RNA interactions, as observed in atomic-resolution RNA structures. They constitute the modular building blocks of RNA architecture, which is organized hierarchically. Recent work has focused on analyzing RNA backbone conformations to identify, define and search for new instances of recurrent motifs in X-ray structures. One current view asserts that recurrent RNA strand segments with characteristic backbone configurations qualify as independent motifs. Other considerations indicate that, to characterize modular motifs, one must take into account the larger structural context of such strand segments. This follows the biologically relevant motivation, which is to identify RNA structural characteristics that are subject to sequence constraints and that thus relate RNA architectures to sequences.

Base Pairing↗
PubMed2004

Effects of deep brain stimulation of the subthalamic nucleus on sleep architecture in parkinsonian patients.

Patients affected by Parkinson's disease (PD) often complain of disturbed sleep resulting from nighttime motor disabilities such as nocturnal akinesia, tremor and rigidity, motor behaviour during REM sleep or periodic leg movements (PLM) during sleep. Sleep may also be affected by dopaminergic and anticholinergic drugs or coexisting depressive syndrome. Deep brain stimulation (DBS) of subthalamic nucleus (STN) effectively reduces PD motor disability. The aim of this study is to evaluate the sleep architecture modifications after STN DBS. We assessed five patients (two men and three women, mean age 63.8+/-3.3 years, with a mean history of PD of 13.8+/-4.9 years) who underwent STN DBS. The mean levodopa equivalent dosage (LED) was 1010+/-318 mg before surgery and 116+/-93 mg 3 months after surgery. Polysomnography (PSG) with audiovisual recordings was performed on two separate nights, the first assessment in the week before surgery and the second 3 months after surgery. Three months after surgery, PSG showed an increase in total sleep time, in the longest period of uninterrupted sleep, and in the percentage of stage 3-4 NREM sleep, while there was a reduction of wakefulness after sleep onset. PLM, apnea-hyopnea index and REM sleep behaviour disorder were unaffected by STN DBS. STN DBS seems to be an effective therapeutic option for the treatment of advanced Parkinson's disease because it improves the cardinal symptoms and also seems to improve sleep architecture.

Antidepressive Agents↗
PubMed2006

Opioids, sleep architecture and sleep-disordered breathing.

Opioid use whether acute or chronic, illicit or therapeutic is prevalent in Western societies. Opioid receptors are located in the same nuclei that are active in sleep regulation and opioid peptides are suggested to be involved in the induction and maintenance of the sleep state. mu-Opioids are the most commonly used opioids and are recognized respiratory depressants that cause abnormal awake ventilatory responses to hypercapnia and hypoxia. Abnormal sleep architecture has been reported during the process of opioids induction, maintenance and withdrawal. During induction and maintenance of opioid use there is reduction of rapid eye movement (REM) sleep and slow wave sleep. More recently, central sleep apnoea (CSA) has been reported with chronic opioid use and 30% of stable methadone maintenance treatment patients have CSA. Given these facts, it is sobering to note the paucity of human data available regarding the effects of short and long-term opioid use on sleep architecture and respiration during sleep. In this manuscript, we review the current knowledge regarding the effects of mu-opioids on sleep and respiration during sleep and suggest research pathways to advance our knowledge and to explore the possible responsible mechanisms related to these effects.

Analgesics, Opioid↗
PubMed2006

Genetic architecture of the dog: sexual size dimorphism and functional morphology.

Purebred dogs are a valuable resource for genetic analysis of quantitative traits. Quantitative traits are complex, controlled by many genes that are contained within regions of the genome known as quantitative trait loci (QTL). The genetic architecture of quantitative traits is defined by the characteristics of these genes: their number, the magnitude of their effects, their positions in the genome and their interactions with each other. QTL analysis is a valuable tool for exploring genetic architecture, and highlighting regions of the genome that contribute to the variation of a trait within a population.

Animals↗
PubMed2003

New roles for astrocytes: redefining the functional architecture of the brain.

Astrocytes have traditionally been considered ancillary, satellite cells of the nervous system. However, work over the past decade has revealed that they interact with the vasculature to form a gliovascular network that might organize not only the structural architecture of the brain but also its communication pathways, activation, thresholds and plasticity. The net effect is that astroglia demarcate gray matter regions, both cortical and subcortical, into functional compartments whose internal activation thresholds and external outputs are regulated by single glial cells. The array of these astrocyte-delimited microdomains along the capillary microvasculature allows the formation of higher-order gliovascular units, which serve to match local neural activity and blood flow while regulating neuronal firing thresholds through coordinative glial signaling. By these means, astrocytes might establish the functional as well as the structural architecture of the adult brain.

Animals↗
PubMed2026

A conserved distal-tail helical extension defines a tailspike attachment architecture in Gram-negative siphophages.

Rapid growth of bacteriophage genome collections has outpaced functional annotation of tail-tip proteins, limiting comparative analysis of host-recognition structures. Starting from a shared distal-tail gene organization in the Salmonella phages 9NA and Jersey, I developed a morphogenetic bioinformatic framework integrating gene synteny, sequence comparison, profile hidden Markov model (HMM) screening, structural evidence, structure-aware searching, and AlphaFold modeling. Comparison with the experimentally characterized lambda and Sf11 tail assemblies identified a predominantly alpha-helical C-terminal extension of the distal-tail (DT) protein associated with tailspike attachment, termed the distal-tail helical extension (DT-helix). Screening 541,986 proteins from 5167 complete NCBI RefSeq tailed-phage genomes, followed by evidence-based evaluation of sequence, genomic context, and structural architecture, identified 165 curated DT-helical-extension-associated phages. Their DT proteins segregated into six sequence groups. In the four principal multi-member groups, cognate tailspikes showed group-specific conservation in proximal N-terminal regions but substantially greater downstream diversity, consistent with sequence constraint at the DT-tailspike attachment boundary. A complementary ProstT5/Foldseek search supported the established groups but revealed no convincing additional highly divergent family. Together with the experimentally characterized Sf11 attachment interface, these findings define a recurrent morphogenetic architecture linking conserved distal-tail scaffolds to more variable receptor-binding proteins across siphophages infecting Gram-negative bacteria. Although universal exchangeability is not established, the identified scaffold-receptor-binding boundaries provide a framework for molecular characterization and rational phage engineering. Accession-level information for the 165 curated phages is available through PhageTailDB.

Viral Tail Proteins↗
PubMed2006

Loss of selenoprotein N function causes disruption of muscle architecture in the zebrafish embryo.

Mutations in the gene coding for selenoprotein N (SelN), a selenium containing protein of unknown function, cause different forms of congenital muscular dystrophy in humans. These muscular diseases are characterized by early onset of hypotonia which predominantly affect in axial muscles. We used zebrafish as a model system to understand the function of SelN in muscle formation during embryogenesis. Zebrafish SelN is highly homologous to its human counterpart and amino acids corresponding to the mutated positions in human muscle diseases are conserved in the zebrafish protein. The sepn1 gene is highly expressed in the somites and notochord during early development. Inhibition of the sepn1 gene by injection of antisense morpholinos does not alter the fate of the muscular tissue, but causes muscle architecture disorganization and greatly reduced motility. Ultrastructural analysis of the myotomes reveals defects in muscle sarcomeric organization and in myofibers attachment, as well as altered myoseptum integrity. These studies demonstrate the important role of SelN for muscle organization during early development. Moreover, alteration of myofibrils architecture and tendon-like structure in embryo deficient for SelN function provide new insights into the pathological mechanism of SelN-related myopathy.

Amino Acid Sequence↗
PubMed2003

Development of abnormal tissue architecture in transplanted neonatal rat myocytes.

BACKGROUND: Most myocardial cell transplant studies focus on demonstration of improved function; however, such improvement depends on the development of appropriate tissue structure. Thus, our aim was to assess the architectural changes that occurred after cell transplant into normal and infarcted myocardium. METHODS: Male neonatal cells (1 to 2 days old) were injected into the left ventricular free wall of adult female rats. The tissue was examined 0 to 1 days and 1 to 2, 4 to 6, and 12 weeks later in noninfarcted hearts and 6 months after transplant into infarcts. In histologic sections, we assessed the cells' retardation of polarized light (to measure development of contractile elements), two-dimensional cell orientation, cell nuclear morphology, and collagen content. RESULTS: The transplant cells' retardation of polarized light gradually increased to 81% of that of host cells after 6 months (p < 0.001). The transplant cells were disorganized and although their nuclei increased in size, they always had a rounded appearance. Collagen content in the transplant was 210% to 430% higher than in host tissue (p < 0.01). In addition, scar collagen always separated transplant and host cells. CONCLUSIONS: One architectural feature, the rounded nuclei, provided a distinctive marker to identify transplanted cells. Nevertheless, the transplants' inhibited muscle development together with disorganization, separation from the host muscle, and a substantial increase in collagen resulted in a structure unlikely to play an active role in systolic function.

Animals↗
PubMed2000

Acute effects of mirtazapine on sleep continuity and sleep architecture in depressed patients: a pilot study.

BACKGROUND: Mirtazapine, a clinically effective antidepressant, acts by antagonizing central alpha2-adrenergic and 5-HT2/5-HT3 receptors. No data are available regarding mirtazapine's effects on sleep architecture in patients with major depressive disorder. METHODS: Six patients meeting criteria for major depressive disorder and scoring > or =4 on the three Hamilton Depression Rating Scale sleep items were studied. Polysomnographic evaluations were performed at baseline and after 1 (15 mg at bedtime) and 2 weeks (30 mg at bedtime) of open-label mirtazapine treatment. RESULTS: Mirtazapine significantly decreased sleep latency and significantly increased total sleep time and sleep efficiency from baseline levels during week 1, with similar results observed after week 2. Mirtazapine did not significantly alter rapid eye movement sleep parameters. Clinically, Hamilton Depression Rating Scale and sleep disturbance ratings improved after treatment. CONCLUSIONS: Mirtazapine significantly improves sleep continuity in major depressive disorder patients with poor sleep quality at weeks 1 and 2 of treatment, while preserving sleep architecture.

Adolescent↗
PubMed2001

Demonstration of primary and secondary muscle fiber architecture of the bovine tongue by diffusion tensor magnetic resonance imaging.

The myoarchitecture of the tongue is comprised of a complex array of muscle fiber bundles, which form the structural basis for lingual deformations during speech and swallowing. We used magnetic resonance imaging of the water diffusion tensor to display the primary and secondary fiber architectural attributes of the excised bovine tongue. Fiber orientation mapping provides a subdivision of the tongue into its principal intrinsic and extrinsic muscular components. The anterior tongue consists of a central region of orthogonally oriented intrinsic fibers surrounded by an axially oriented muscular sheath. The posterior tongue consists principally of a central region of extrinsic fibers, originating at the inferior surface and projecting in a fan-like manner in the superior, lateral, and posterior directions, and lateral populations of extrinsic fibers directed posterior-inferior and posterior-superior. Analysis of cross-fiber anisotropy indicates a basic contrast of design between the extrinsic and the intrinsic fibers. Whereas the extrinsic muscles exhibit a uniaxial architecture typical of skeletal muscle, the intrinsic core muscles, comprised of the verticalis and the transversus muscles, show strong cross-fiber anisotropy. This pattern is consistent with the theory that the tongue's core functions as a muscular hydrostat in that conjoint contraction of the transverse and vertical fibers enable the tissue to expand at right angles to these fibers. These findings suggest that three-dimensional analysis of diffusion tensor magnetic resonance imaging provides a structural basis for understanding the micromechanics of the mammalian tongue.

Animals↗
PubMed2003

Atomic force microscopy of pea starch granules: granule architecture of wild-type parent, r and rb single mutants, and the rrb double mutant.

AFM studies have been made of the internal structure of pea starch granules. The data obtained provides support for the blocklet model of starch granule structure (Carbohydr. Polym. 32 (1997) 177-191). The granules consist of hard blocklets dispersed in a softer matrix material. High-resolution images have yielded new insights into the detailed structure of growth rings within the granules. The blocklet structure is continuous throughout the granule and the growth rings originate from localised defects in blocklet production distributed around the surface of spheroidal shells within the granules. A mutation at the rb locus did not lead to significant changes in granule architecture. However, a mutation at the r locus led to loss of growth rings and changed blocklet structure. For this mutant the blocklets were distributed within a harder matrix material. This novel composite arrangement was used to explain why the granules had internal fissures and also changes in gelatinisation behaviour. It is suggested that the matrix material is the amylose component of the granule and that both amylose and amylopectin are present within the r mutant starch granules in a partially-crystalline form. Intermediate changes in granule architecture have been observed for the double mutant rrb.

Microscopy, Atomic Force↗
PubMed2006

Beyond a single area: motor control and language within a neural architecture encompassing Broca's area.

In this position paper, we discuss a neural architecture comprising three major cortical systems: the inferior frontal cortex (including Broca's area), the rostral part of the posterior parietal cortex, and the superior temporal cortex. This network of areas is critical to imitation and to language. What are the functional properties of the network that make it possible for imitation and language to co-exist within the same neural architecture? We propose that this network implements cortical forward and inverse modeling for actions and speech sounds of self and others.

Frontal Lobe↗
PubMed2002

Beta-helical catalytic domains in glycoside hydrolase families 49, 55 and 87: domain architecture, modelling and assignment of catalytic residues.

X-ray crystallography and bioinformatics studies reveal a tendency for the right-handed beta-helix domain architecture to be associated with carbohydrate binding proteins. Here we demonstrate the presence of catalytic beta-helix domains in glycoside hydrolase (GH) families 49, 55 and 87 and provide evidence for their sharing a common evolutionary ancestor with two structurally characterized GH families, numbers 28 and 82. This domain assignment helps assign catalytic residues to each family. Further analysis of domain architecture reveals the association of carbohydrate binding modules with catalytic GH beta-helices, as well as an unexpected pair of beta-helix domains in GH family 55.

Amino Acid Sequence↗
PubMed2002

Novel magnified endoscopic findings of microvascular architecture in intramucosal gastric cancer.

BACKGROUND: The color change observed endoscopically in early gastric cancer is thought to correlate with vascular density and architecture. This study investigated the endoscopic microvascular architecture in intramucosal gastric carcinoma in vivo. METHODS: Intramucosal gastric carcinomas without ulceration in 27 patients were studied by using a new magnifying upper endoscope with attention to microvascular findings. The carcinomas were divided into two major types histologically: differentiated (18) and undifferentiated (9). RESULTS: A regular subepithelial capillary network was demonstrated in noncancerous mucosa. The appearance of the carcinomas differed depending on histologic differentiation. With all of the differentiated carcinomas, there was a well-demarcated area where the regular capillary pattern of noncancerous mucosa had disappeared and irregular microvessels were proliferating. In contrast, with undifferentiated carcinomas there was only an ill-defined area with disappearance or a reduction in the density of capillaries in the noncancerous mucosa. CONCLUSIONS: Magnified endoscopic observation of microvessels may be of assistance in the identification of intramucosal gastric carcinomas that exhibit only subtle changes in color and shape at standard endoscopy.

Endoscopes↗