Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CELL STRUCTURE”

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.

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

At least 55 records · Page 3Linked to original sources
PubMed1997

The use of confocal microscopy in the investigation of cell structure and function in the heart, vascular endothelium and smooth muscle cells.

In recent years, fluorescence microscopy imaging has become an important tool for studying cell structure and function. This non invasive technique permits characterization, localisation and qualitative quantification of free ions, messengers, pH, voltage and a pleiad of other molecules constituting living cells. In this paper, we present results using various commercially available fluorescent probes as well as some developed in our laboratory and discuss the advantages and limitations of these probes in confocal microscopy studies of the cardiovascular system.

Animals↗
PubMedDate not supplied

Role of target and effector cell structures in natural killer-mediated cytotoxicity.

An analysis of target and effector cell structures involved in the in vitro natural killer (NK)-mediated cytotoxicity has been performed. The degree of surface expression of transferrin receptor (TR) was only in part correlated with that of cell lysis. Moreover, the lysis could not be blocked by treating target cells with two anti-TR monoclonal antibodies. Finally, cell lines poorly affected by NK cells express TR only at the cytoplasmic level. As to the effector cells, the integrity of cytoskeleton components (especially microtubules) was found to be essential for the occurrence of cell lysis. In fact, vinblastine, an anti-microtubule agent, was able to significantly reduce the percentage cell lysis. This effect was not due to a selective depletion in NK cells induced by the drug. It is concluded that the mechanisms underlying NK activity are complex and involve both target and effector cell structures.

Cell Line↗
PubMed1987

Analysis of cell structural and functional diversity by combination of micromanipulation and microfluorimetry.

Fluorescent molecules are widely used to study quantitative cell properties, such as density of different antigenic markers or membrane responses to various stimuli. In most cases, studies are done on bulk cell populations with a spectrofluorimeter or at the single cell level with a cytofluorograph. However, only microspectrofluorimetric techniques allow continuous recording of dynamic events undergone by individual cells. The aim of the present report was twofold: first, to describe a methodology easily accessible to cell biologists that allows simultaneous manipulation of single cells and measurements of their fluorescence properties; and second, through this methodology to study quantitative aspects of cell structure and function such as binding of a fluorescein-labeled lectin, transfer of fluorescent molecules between labeled and unlabeled cells brought in close contact, or fluorescence response of individual cells stimulated after being loaded with a potential-sensitive dye. We conclude that the understanding of many aspects of cell structure and behavior requires that individual cells be studied under dynamic conditions and for prolonged periods of time.

Animals↗
PubMed2003

Tensegrity I. Cell structure and hierarchical systems biology.

In 1993, a Commentary in this journal described how a simple mechanical model of cell structure based on tensegrity architecture can help to explain how cell shape, movement and cytoskeletal mechanics are controlled, as well as how cells sense and respond to mechanical forces (J. Cell Sci. 104, 613-627). The cellular tensegrity model can now be revisited and placed in context of new advances in our understanding of cell structure, biological networks and mechanoregulation that have been made over the past decade. Recent work provides strong evidence to support the use of tensegrity by cells, and mathematical formulations of the model predict many aspects of cell behavior. In addition, development of the tensegrity theory and its translation into mathematical terms are beginning to allow us to define the relationship between mechanics and biochemistry at the molecular level and to attack the larger problem of biological complexity. Part I of this two-part article covers the evidence for cellular tensegrity at the molecular level and describes how this building system may provide a structural basis for the hierarchical organization of living systems--from molecule to organism. Part II, which focuses on how these structural networks influence information processing networks, appears in the next issue.

Actin Cytoskeleton↗
PubMedDate not supplied

High-resolution field emission scanning electron microscope imaging of internal cell structures after Epon extraction from sections: a new approach to correlative ultrastructural and immunocytochemical studies.

The availability of high-resolution field emission scanning electron microscopes (FESEM) and the recent development of a less destructive method for extracting Epon from sections motivated us to investigate these techniques for the study of internal cell structures. We chose the nuclear pore complex (NPC) and insect striated muscle as test objects. Chemically fixed or rapidly cryoimmobilized samples were embedded in Epon 812. The Epon was extracted from 200- to 300-nm-thick sections with a modified potassium methoxide-crown ether complex. The samples were viewed with high-resolution FESEM at low voltages. In tangential sections of isolated nuclear envelopes from Xenopus oocytes the cytoplasmic and intranuclear components ("fishtraps") of NPCs appeared identical to what has been described from whole mounts. In cross sections, fishtraps are seen in side view, which is possible only with this technique. In longitudinal and cross sections of insect flight muscle the classical arrangement of myofilaments and cross-bridges is well preserved. This method now makes it possible to image internal cell structures from any desired angle by high-resolution FESEM. Immunolabeling studies on the rabbit psoas muscle demonstrated that antigenicity of alpha-actinin was retained in Epon-extracted sections. Immunogold labeling with antibodies against alpha-actinin conjugated to 3-nm gold beads was intense, highly specific, and restricted to the Z lines. This method can overcome the penetration problem of immunogold labeling, since any cell component can be positioned at the surface of the section. Obviously this approach can become a powerful new tool for many areas of structural cell biology.

Actinin↗
PubMed1997

Luteinizing hormone on Leydig cell structure and function.

The effects of luteinizing hormone (LH) and human chorionic gonadotrophic hormone (hCG) on Leydig cell structure and function are reviewed in this paper under two main headings; responses to LH and hCG stimulation and responses to LH deprivation. With acute LH stimulation, up to 2 hours following the LH injection, there was no change in the volume of a Leydig cell. However, Leydig cell peroxisomal volume and intraperoxisomal SCP2 content showed a rapid and transient change. These changes can be considered to be specific because: i) no other Leydig cell organelle including smooth endoplasmic reticulum (SER) showed such a change, and ii) only the intraperoxisomal SCP2 but not catalase (a marker enzyme for peroxisomes) showed such a change within 30 minutes of LH stimulation. As these changes occurred prior to the peak testosterone levels following this treatment, it is suggested that SCP2 and peroxisomes may have an association with testosterone biosynthesis prior to cholesterol transport into mitochondria. With LH or hCG stimulation for longer periods, i.e. one day or more, the same morphological changes are produced in Leydig cells irrespective of the age of the species, dosage of LH or hCG, and with single or multiple doses. These changes include, Leydig cells hypertrophy and/or hyperplasia, increase in the cellular organelle content (mostly SER and mitochondria) and depletion of lipid droplets. In addition, a recent study showed that Leydig cell peroxisomal volume, SCP2 content, the amount of intraperoxisomal SCP2 and testosterone secretory capacity were also significantly increased in response to chronic LH treatment. The effects of LH deprivation by whatever means (e.g. hypophysectomy, with testosterone and 17 beta-estradiol silastic implants, LH antisera) on Leydig cell structure and function is generally described as opposite to those observed following LH or hCG stimulation. These include Leydig cell hypotrophy and hypoplasia, reductions in the cytoplasmic organelle content in general and specific reductions in SER and peroxisomal volumes, reductions in total catalase and SCP2 in Leydig cells together with reductions in the intraperoxisomal SCP2 content in Leydig cells and their testosterone secretory capacity.

Animals↗
PubMed2004

Imaging the cell surface: argon sputtering to expose inner cell structures.

Established microscopies such as Scanning Electron Microscopy (SEM) and more recent developments such as Atomic Force Microscopy (AFM) and X-ray Photo-Electron Emission spectroMicroscopy (X-PEEM) can only image the sample surface. We present an argon sputtering method able to progressively expose inner cell structures without apparent damage. By varying the sputtering time, the structure of cell cytoskeleton, vesicles, mitochondria, nuclear membrane, and nucleoli can be imaged. We compared images obtained with confocal fluorescence microscopy, transmission electron microscopy (TEM), SEM, and X-PEEM on similar samples after argon sputtering, then confirmed the similarity of reference intracellular structures, including cytoskeleton fibers, cell-cell and cell-substrate adhesion structures, and secretory vesicles. We conclude that the sputtering method is a new valuable tool for surface sensitive microscopies.

Argon↗
PubMed1984

[Identification of cell structure antigens of the causative agent of melioidosis by a 2-dimensional immunoelectrophoresis method].

The antigenic composition of some cell structures of P. pseudomallei has been studied and the chemical nature of the antigens has been determined by the method of two-dimensional electrophoresis. In some cell components common antigens have been detected; at the same time these components have been found to possess their own characteristic antigenic complexes. The place of the cell structure antigens in the total antigenic structure of P. pseudomallei has been determined.

Antigens, Bacterial↗
PubMed1992

Sample preparation for electron microscopy of internal cell structure.

Methods are reviewed for examination of internal cell structure by high-resolution scanning electron microscopy and compared with the rapid-freeze deep-etch replica technique used in transmission electron microscopy. Rapid freezing of fresh material, followed by freeze-fracture, provides a theoretically attractive approach in ultrastructure studies, but the high protein and solute content of most cells prevents a deep three-dimensional view for material frozen without some form of extraction. After discussion of other methods it is concluded that the most useful general approach, at least for cultured cells, is to first permeabilize or break open the cells in a medium which preserves the structure under study in a functional state as, for example, the movement of chromosomes along the division spindle, or transport of proteins within the Golgi region. After permeabilization, with attendant partial extraction, the preparation can be fixed, then viewed by either deep-etch replication, or by high-resolution scanning electron microscopy, with structure of interest revealed in deep view.

Animals↗
PubMed2000

The role of cleavage of cell structures during apoptosis.

In this work we have studied the behavior of some cell structures, such as actin, tubulin and chromatin during apoptosis induced in F9 cells after retinoic acid treatment. In this experimental model, all defined steps of morphological changes described for apoptosis are observed. The correlation between a partial maintenance of F-actin and microtubular structures and the spatial distribution of F-actin suggests a possible relationship between this molecule and the characteristic shape changes observed in apoptosis. Additionally, the disposition of monomeric G-actin suggests a possible relationship between the fragmentation of this molecule and the cleavage of DNA. The analysis of the U2af1-rs1 specific sequence shows that the internucleosomal fragmentation observed in this gene is randomly produced during apoptosis and is not dependent of demethylation status. The results obtained confirm that specific cleavage of these cell structures is inherent to the development of the apoptotic process and do not exclude the possibility that proteolysis of key actin and/or tubulin molecules or the cleavage of specific chromatin sequences other than the ones analyzed here, could control the different phases of the apoptotic process.

Actins↗
PubMed2000

Expression of AtPRP3, a proline-rich structural cell wall protein from Arabidopsis, is regulated by cell-type-specific developmental pathways involved in root hair formation.

The tightly regulated expression patterns of structural cell wall proteins in several plant species indicate that they play a crucial role in determining the extracellular matrix structure for specific cell types. We demonstrate that AtPRP3, a proline-rich cell wall protein in Arabidopsis, is expressed in root-hair-bearing epidermal cells at the root/shoot junction and within the root differentiation zone of light-grown seedlings. Several lines of evidence support a direct relationship between AtPRP3 expression and root hair development. AtPRP3/beta-glucuronidase (GUS) expression increased in roots of transgenic seedlings treated with either 1-aminocyclopropane-1-carboxylic acid (ACC) or alpha-naphthaleneacetic acid (alpha-NAA), compounds known to promote root hair formation. In the presence of 1-alpha-(2-aminoethoxyvinyl)glycine (AVG), an inhibitor of ethylene biosynthesis, AtPRP3/GUS expression was strongly reduced, but could be rescued by co-addition of ACC or alpha-NAA to the growth medium. In addition, AtPRP3/GUS activity was enhanced in ttg and gl2 mutant backgrounds that exhibit ectopic root hairs, but was reduced in rhd6 and 35S-R root-hair-less mutant seedlings. These results indicate that AtPRP3 is regulated by developmental pathways involved in root hair formation, and are consistent with AtPRP3's contributing to cell wall structure in Arabidopsis root hairs.

Amino Acids↗
PubMed2004

Understanding actin organization in cell structure through lattice based Monte Carlo simulations.

Understanding the connection between mechanics and cell structure requires the exploration of the key molecular constituents responsible for cell shape and motility. One of these molecular bridges is the cytoskeleton, which is involved with intracellular organization and mechanotransduction. In order to examine the structure in cells, we have developed a computational technique that is able to probe the self-assembly of actin filaments through a lattice based Monte Carlo method. We have modeled the polymerization of these filaments based upon the interactions of globular actin through a probabilistic model encompassing both inert and active proteins. The results show similar response to classic ordinary differential equations at low molecular concentrations, but a bi-phasic divergence at realistic concentrations for living mammalian cells. Further, by introducing localized mobility parameters, we are able to simulate molecular gradients that are observed in nonhomogeneous protein distributions in vivo. The method and results have potential applications in cell and molecular biology as well as self-assembly for organic and inorganic systems.

Actins↗
PubMed2006

Cell structure of barb ridges in down feathers and juvenile wing feathers of the developing chick embryo: barb ridge modification in relation to feather evolution.

The present study deals with the cell structure and three-dimensional organization of barb and barbule cells within barb ridges of down feathers and juvenile feathers in the chick embryo. Juvenile feathers represent the second generation of feathers in the wing, and replace down feathers some weeks after hatching. Within the follicle of juvenile feathers, at 16-18 days of embryonic development, barb ridges are more numerous than in down feathers. Barb ridges of juvenile feathers contain more cells in their barbule and axial plates with respect to barb ridges of down feathers. This condition determines the formation of longer barbules inserted in the rami of juvenile feathers than barbules of down feathers. Barb ridges of juvenile feathers merge with the rachidial ridge so that pennaceous feathers are formed. Barbule cells are surrounded by cytoplasmic elongation from barb vane ridge cells located in the axial plate, which constitute most of the axial plate. The degeneration of supportive cells among barbule cells branching from barbs determine the formation of spaces between barbules. The study emphasizes that, in addition to the size of the dermal papilla, it is the length of barb ridges and the infiltration of barb ridge vane cells among barbule cells that determine the size and length of feathers. The knowledge of the cell structure of barb ridges allows understanding not only of how feathers develop but also gives insights into their evolution. Based on changes of the process of barb ridge morphogenesis some hypotheses on the evolution of plumulaceous and pennaceous feathers are presented. Feathers derived from the process of carving-out supportive cells within barb ridges and from the specific pattern of fusion of barb/barbule cells. This process initially produced variably branched down feathers and later, after barb ridge fusion, a rachis. From the modulation in the pattern of barb ridge formation various pennaceous feathers later evolved.

Animals↗
PubMed2006

Specialization of pyramidal cell structure in the visual areas V1, V2 and V3 of the South American rodent, Dasyprocta primnolopha.

Marked phenotypic variation has been reported in pyramidal cells in the primate cerebral cortex. These extent and systematic nature of these specializations suggest that they are important for specialized aspects of cortical processing. However, it remains unknown as to whether regional variations in the pyramidal cell phenotype are unique to primates or if they are widespread amongst mammalian species. In the present study we determined the receptive fields of neurons in striate and extrastriate visual cortex, and quantified pyramidal cell structure in these cortical regions, in the diurnal, large-brained, South American rodent Dasyprocta primnolopha. We found evidence for a first, second and third visual area (V1, V2 and V3, respectively) forming a lateral progression from the occipital pole to the temporal pole. Pyramidal cell structure became increasingly more complex through these areas, suggesting that regional specialization in pyramidal cell phenotype is not restricted to primates. However, cells in V1, V2 and V3 of the agouti were considerably more spinous than their counterparts in primates, suggesting different evolutionary and developmental influences may act on cortical microcircuitry in rodents and primates.

Action Potentials↗
PubMed2006

[Isoflavone accumulation associated with cell structural changes in Maackia amurensis suspension cultures elicited by methyl jasmonate, salicylic acid and nitric oxide].

Comparison between changes in isoflavone accumulation and cell structure in Maackia amurensis suspension cultures elicited by methyl jasmonate (MeJA),salicylic acid (SA) and nitric oxide (NO) was studied. The results suggested that MeJA, SA and NO can all stimulate isoflavone production remarkably. After 9d treatment with 200 micromol/L MeJA,100 micromol/L SA and 50 micromol/L SNP, the isoflavone content was 417.18%, 185.45% and 222.45% of the control, respectively. At the same time, the electron-dense body (EDB) could be easily found in the cells, while its number achieved most after 9 d treatment,and the number of EDB and isoflavone content were positive correlated. It was deduced that elicitors stimulated plant secondary metabolites production associated with changes in cell structure.

Acetates↗
PubMed1987

Observations of glomerular epithelial cell structure in patients with type I diabetes mellitus.

Overt proteinuria is a hallmark of diabetic nephropathy while microalbuminuria is thought to be a predictor of later onset of diabetic nephropathy. Yet the mechanisms for abnormal urinary protein leak in diabetes have not been defined. We studied 28 patients with type I diabetes for 7 to 33 years. Creatinine clearance, urinary albumin excretion rate (UAE), and multiple blood pressures were obtained in each patient. A renal biopsy was performed in each patient and in 28 normal subjects. Quantitative stereology was used to determine foot process (FP) width, filtration slit length density (FSLV) and filtration slit length/glomerulus (FSLG). FP width was slightly wider than normal in diabetic patients with UAE less than 250 mg/24 hr while FP was significantly wider than both of these groups in diabetics with UAE greater than 250 mg/24 hr. FSLV and FSLG were similar in normals and diabetics with UAE less than 250 mg/24 hr but both were reduced in diabetics with UAE greater than 250 mg/24 hr. UAE correlated with FP width (P less than 0.05), FSLG (P less than 0.01) and most precisely and FSLV (P less than 0.001). Diabetics with microalbuminuria had values for all the structural parameters measured here not different from diabetics with UAE in the normal range. Perturbations of epithelial cell structure are present in diabetes mellitus especially in patients with nephropathy. The exact relationships between albuminuria and epithelial cell structure remains to be elucidated.

Adult↗
PubMed2001

In vitro effects of transcatheter injection on structure, cell viability, and cell metabolism in fibroblast-impregnated alginate microspheres.

PURPOSE: To determine if microsphere-encapsulated cell preparations can be delivered through a microcatheter without compromising microsphere structure, cell viability, or metabolism. MATERIALS AND METHODS: Fibroblast-impregnated microspheres were fabricated by using 1.0% alginate and rabbit synovial fibroblasts. Fibroblast-impregnated alginate microspheres injected through microcatheters were analyzed in parallel with identical noninjected microspheres. The effects of transcatheter injection on structure and cell viability (percentage of viable cells per microsphere) were correlated with microsphere size. Structural effects were analyzed by using light microscopy, and 7-day percentage (ratio of live cells to dead cells) cell viability was assessed with confocal microscopy and fluorescent staining. In a second series of experiments, the metabolism of small microspheres was studied during a course of 7 days by using a spectrophotometric bioanalyzer. RESULTS: Transcatheter injection caused fracturing and/or fragmentation of large (800-1,000 microm) and medium (500-750 microm) microspheres, while small (250-400 microm) microspheres were structurally unaffected by transcatheter injection. Fracturing and fragmentation were associated with cell release from the alginate matrix. Although transcatheter injection reduced cell viability by 17%-23% in all size categories, it did not cause a detectable alteration in the rate of glucose metabolism. CONCLUSION: Transcatheter injection was physiologically well tolerated by fibroblasts encapsulated in alginate microspheres; however, when microsphere diameter exceeded the catheter diameter, fracturing and fragmentation of microspheres compromised the sequestration function of the microsphere vector.

Alginates↗