Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cellular Structures”

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 847 records · Page 47Linked to original sources
PubMed1998

Mechanism underlying the strong positive inotropic effects of LND-623: specific inhibition of Na, K-ATPase isoforms and exclusion of cellular sites of contractile control.

LND-623 is a new aminosteroid analog of ouabain, with a greater separation between efficacy and toxicity than ouabain. To determine its mechanism of action, we studied its biochemical and physiological effects on human red blood cell sodium transports on different cellular structures regarded as sites of contractile control, and we compared its relative efficacy to ouabain in rat heart preparations and membrane-bound Na, K-ATPase isoenzymes. The response to ouabain was evaluated in Langendorff-perfused hearts and on purified membrane-bound Na, K-ATPase. LND-623 is 6.8-fold more efficient than ouabain in inhibiting the human Na+ pump (IC50 = 0.098 +/- 0.001 microM vs. 0.67 +/- 0.02 microM); (P < 0.0001). LND-623 had no effect on the following cellular functions: Na-Ca exchange, Na-K cotransport, Ca-ATPase, slow calcium channels, adenylate cyclase system, phosphodiesterase, and calcium sensitivity of the contractile protein system. The dose-response curve for the positive inotropic and inhibitory effects on rat cardiac isoenzymes produced by LND-623 were clearly biphasic. The amplitude of the maximum inotropic effect, without any toxic effect, was up to three-fold higher with LND-623 than with the same maximum dose of ouabain used. The strong positive inotropic effect of LND-623 in rats could be related to a specific inhibition of the two rat cardiac isoforms of the Na, K-ATPase.

Adenylyl Cyclases↗
PubMed1994

A rapid method for whole mount preparations of mammalian oocytes and early embryos.

Whole mounts of mouse oocytes and embryos are useful for observing intracellular structures while preserving morphological integrity. This method is inconvenient for rapid processing of a large number of specimens because washing each specimen in a protein-free solution is required prior to transfer into the fixative. We have developed a new fixative which does not cause protein precipitation which can be added directly to the culture medium. Specimens can be preserved in culture dishes for at least one month, and processed for cytological observation at a convenient time. When stained with hematoxylin, details of cellular structures such as nuclei, nucleoli, chromosomes and spindle microtubules can be observed while maintaining the organization of the organelles.

Animals↗
PubMed1991

A two-step liquid culture--a novel culture procedure for studying erythroid cell development.

The red blood cell (RBC) has a major contribution to biological research. For example, the basic knowledge on the structure and function of the plasma membrane and the structure, function and genetics of proteins came from studies of RBC and hemoglobin (Hb). The reasons why the RBC has become such a useful experimental tool is due to several facts: (a) peripheral blood (PB) is readily available; (b) pure populations of RBC can be easily isolated from other blood cells; (c) RBC can be maintained in vitro for weeks under simple conditions (physiological salt solution at 4 degrees C) and finally, (d) the mature RBC is a rather simplified cell that lost many cellular structures and functions as a result of its extreme specialization. When studying the developmental aspects of erythroid cell differentiation and maturation, one faces a more complicated situation. Like other hemopoietic cells, the origin of RBC is in precursors in the bone marrow (BM). However, unlike PB, BM is not readily available and it consists of a mixture of cells of various types and stages of differentiation, which makes the purification of a particular cell population quite difficult.

Biomarkers↗
PubMed1984

Drug-induced cardionecrosis.

Cardiotoxicity may be defined as a drug action producing abnormalities in cardiac function, such as transitory disturbances or rhythm, conduction or contractility. Clearance of the drug is followed by recovery of the initial function. Cardionecrosis is the irreversible consequence of cardiotoxicity. Its appearance depends not only upon the toxicological potency of a given compound but may also depend upon the pathophysiological state of the heart. Therefore, two main categories may be recognized considering the influence of this state. Drugs may act on the processes controlling cellular structure such as protein biosynthesis in the case of antibiotics of the anthracycline group. Drugs may act at the level of metabolic regulation through a membranal or an intracellular action; in this case, the functional state of the heart plays a major role. This is mainly observed with sympathomimetics and with drugs interacting with the function of catecholamines. The cardiotoxicity observed in such conditions mimics the action of anoxia or of ischemia. The main determinant of the cardiac lesion is probably the disturbance of cellular calcium metabolism. This situation may be prevented (or treated) by the use of calcium entry blockers (calcium antagonists). A great part of this report will deal with the second group of drugs, because of their potential importance as a chemical hazard for the population and because of a possible preventive protection by calcium entry blockers (calcium antagonists).

Anesthetics↗
PubMed1981

[Cellular sites of action and effects of drugs. A review (author's transl)].

Due to the fact that they are used consciously to achieve positive effects on diseases in man, drugs occupy a special position among the large number of substances that affect the cellular structure and function. In view of the basic similarity and/or parallelism of the structural composition and of the metabolic processes of healthy and diseased cells, one can expect effects on the diseased cell and side-effects on healthy cells to form a unity. The aim of any therapy should be to keep the distance between the positive effect and the side-effect as great as possible, which should be examined and carefully weighed in each case. An attempt is made in the present review to examine by giving some examples the problems involved in the cellular effects of drugs and to explain their action. New therapeutic effects can be found and put to use by knowing the cellular site of action.

Animals↗
PubMed2000

A LIM-domain protein from sunflower is localized to the cytoplasm and/or nucleus in a wide variety of tissues and is associated with the phragmoplast in dividing cells.

LIM proteins are important eucaryotic developmental regulators characterized by the presence of one or several double zinc finger motifs, the LIM domains, which are protein-interacting domains. Using the cDNA of the previously described pollen LIM protein PLIM1 from sunflower as a hybridization probe we have isolated the coding sequence for a related protein from cDNA libraries from various sunflower organs. This protein, WLIM1, is 188 amino acids long and, like the pollen protein PLIM1, contains two LIM domains, separated by a 48 residue spacer region. The two sunflower proteins are structurally related to the animal LIM proteins CRP and MLP. A WLIM1 gene transcript was detected by RT-PCR in all vegetative and reproductive plant organs tested. Polyclonal antibodies raised against the bacterially expressed and affinity-purified protein recognize a polypeptide of ca. 50 kDa in these organs. Immunocytochemical studies detect the protein in many cell types in each of these organs where it is localized either to the cytoplasm, the nucleus, or both. The protein is often associated with plastids and smaller cellular structures or organelles. In late anaphase and early telophase of dividing cells from ovaries, stems and roots it accumulates in the phragmoplast, and may therefore also play a role in cytokinesis.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Evaluation of cyropreserved internal thoracic artery as an alternative coronary graft: evidence for preserved functional, metabolic and structural integrity.

The internal thoracic artery (ITA) is the conduit of choice for coronary artery bypass grafting (CABG). This study, utilizing a canine model, evaluates cryopreserved ITA. Sixteen ITAs were harvested and cryopreserved according to United CryoInstitute protocol. Test conduits, 5 cm long and 4 mm mean diameter, were anastomosed to the ligated carotid artery of an unmatched mongrel recipient, above and below the site of native artery ligation. Graft patency was assessed by angiography at 14 days (early) and 980 days (late) postoperatively. Catheterization of the 16 vessels identified three (18%) early and one (6%) late graft occlusion. Ninety days postoperatively, each dog was killed and the graft harvested for histopathological and functional evaluation. Morphologic evaluation, using conventional staining, showed preserved cellular structure, decrease in smooth muscle cells and distorted endothelial layer. Immunocytochemistry, using an antibody against prostacyclin (PGI2), detected PGI2 immunoactivity in the ITA smooth muscle cells. An in vitro assay performed on the arterial rings confirmed preserved functional integrity of the vascular endothelium and smooth muscle. These findings suggest that cryopreserved ITA may have potential as a substitute graft, in devising conduit strategies for primary or reoperative coronary bypass surgery.

Animals↗
PubMed1976

Surface study of tenosynovium in hens and humans by electron microscopy.

A comparative study has been made of the surface structure of the tenosynovium in flexor tendon apparatus obtained from hens and humans. Three different parts of the visceral, and parietal layers, and vincula were observed by scanning electron microscopy. Lining cells of the visceral layer are relatively flat and enmeshed with filamentous fibrils, while those of the parietal layer and the vincula are covered with vesicular and granular particles. Intercellular space is occupied with a close meshwork of filamentous fibrils. These findings are similar in both hens and humans. It is, thus, suggested that the cellular structure varies in the three different parts of the tenosynovium probably in relation to their function.

Animals↗
PubMed1994

Intracellular pH and the control of multidrug resistance.

Many anticancer drugs are classified as either weak bases or molecules whose binding to cellular structures is pH dependent. Accumulation of these drugs within tumor cells should be affected by transmembrane pH gradients. Indeed, development of multidrug resistance (MDR) in tumor cells has been correlated with an alkaline shift of cytosolic pH. To examine the role of pH in drug partitioning, the distribution of two drugs, doxorubicin and daunomycin, was monitored in fibroblasts and myeloma cells. In both cell types the drugs rapidly accumulated within the cells. The highest concentrations were measured in the most acidic compartments--e.g., lysosomes. Modifying the cellular pH in drug-sensitive cells to mimic reported shifts in MDR caused an immediate change in the cellular drug concentration. Drug accumulation was enhanced by acidic shifts and reversed by alkaline shifts. All of these effects were rapid and reversible. These results demonstrate that the alkaline shift observed in MDR is sufficient to prevent the accumulation of chemotherapeutic drugs independent of active drug efflux.

3T3 Cells↗
PubMed2003

Phosphodiesterases in the vascular system.

Cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) are second messengers involved in the intracellular signal transduction of a variety of extracellular stimuli in several tissues. In the vascular system, these nucleotides play important roles in the regulation of vascular tone and in the maintenance of the mature contractile phenotype in smooth muscle cells. Given that cyclic nucleotide signaling regulates a wide variety of cellular functions, it is not surprising that cyclic nucleotide phosphodiesterases (PDEs). In paticular, the accumulating data showing that there are a large number of different PDE isozymes have triggered an equally large increase in interest about these enzymes. At least 11 different gene families of PDEs are currently known to exist in mammalian tissues. Most families contain several distinct genes, and many of these genes are expressed in different tissues as functionally unique alternative splice variants. This article reviews many of the important aspects about the structure, cellular localization, and regulation of each family of PDEs. Particular emphasis is placed on new information obtained in the last few years about vascular disease. The development of novel methods to deliver more potent and selective PDE inhibitors to individual cell types and subcellular locations will lead to new therapeutic uses for this class of drugs in diseases of the vascular system.

Animals↗
PubMedDate not supplied

Transmission of molecular information through electro-magnetic waves with different frequencies and its application to non-invasive diagnosis of patients as well as detection from patient's X-ray film of visible and not visible medical information: Part I.

Our previous study indicates the principle that information on the molecular structure and its quantity will be transmitted bi-directionally through a red-spectrum soft laser beam when specific molecules are placed in the close vicinity of the laser beam. The method was immediately applied for diagnosing diseases or localizing specific substances, using the Bi-Digital O-Ring Test, in moving or stationary animals or human subjects at clearly visible distances, without directly contacting the subject. This principle was also applied for the microscopic Bi-Digital O-Ring Test to examine cellular structures and substances within the cell at the magnified focused projected plane. The method was further expanded to an electron-microscopic Bi-Digital O-Ring Test, where, instead of a light beam as a source of electromagnetic wave carrier, an electron beam was used. Thus, it was possible to study the ultra-fine structure of cells. During the past several years, the author has been experimenting with the question of whether, instead of using visible light in the microscopic Bi-Digital O-Ring Test, if much shorter wavelengths, such as X-ray with strong penetrating force through living tissue, are used as the carriers of molecular information, and if X-ray pictures of the body are evaluated by a similar method as in the microscopic Bi-Digital O-Ring Test, molecular information existing in the pathways of the X-ray through the body might be detectable or not. Our studies indicate that, using X-ray film with good picture quality taken of specific parts of the body, one can detect not only specific microbial infections, such as bacterial, viral, or spirochete (e.g., Lyme), and changes in local chemistry including blood chemistry such as glucose, total cholesterol, uric acid, in major arteries or the heart, but also potentially effective medication. Using the Bi-Digital O-Ring Test resonance phenomenon between a reference control substance and an identical substance or its electromagnetic field imprint, anatomical structures of the soft tissue, such as blood vessels, nerves, and muscles can be identified even when they are not visible on the X-ray film because of the masking effect of other tissues with high density or large volume of tissue. Similar findings were also found in the CAT Scan and MRI pictures of normal and abnormal organs of the body. In this paper, two examples of such analyses, i.e. X-ray films of one patient with adenocarcinoma of the colon and another patient with rheumatoid arthritis of the knee joint are shown.

Arthritis, Infectious↗
PubMed1959

Fine structure of Bacillus subtilis. II. Sporulation progress.

The sporulation process in Bacillus subtilis has been studied principally with KMnO(4) fixation, but also, for the purpose of comparison, with OsO(4) and mixtures of both fixatives. At a very early stage, the pre-spore is seen to consist of what seems to be the nuclear material and granular substance, surrounded by a layer of dense material destined to become the innermost layer of the spore coat. At a subsequent stage, a light interspace is observed that is destined to become the spore cortex. The mature spore shows a very complex structure. The spore coat is composed of three layers, the middle layer of which consisted of 5 to 8 lamellae of thin membranes and interspaces, both about 20 to 25 A thick. Between the inner layer of the spore coat and the spore cortex, a thin membrane with an affinity to the cortex can be observed. The spore coat is enclosed within two envelopes, one loosely surrounding the core, and the other adhering to it. The process of spore maturation has been studied in detail. Certain peculiar cellular structures have been observed that seemed to represent features of abnormal sporulation processes.

Bacillus subtilis↗
PubMed2001

Nitrogen cycling by wood decomposing soft-rot fungi in the "King Midas tomb," Gordion, Turkey.

Archaeological wood in ancient tombs is found usually with extensive degradation, limiting what can be learned about the diet, environment, health, and cultural practices of the tomb builders and occupants. Within Tumulus Midas Mound at Gordion, Turkey, thought to be the tomb of the Phrygian King Midas of the 8th century B.C., we applied a stable nitrogen isotope test to infer the paleodiet of the king and determine the nitrogen sources for the fungal community that decomposed the wooden tomb, cultural objects, and human remains. Here we show through analysis of the coffin, furniture, and wooden tomb structure that the principal degrader, a soft-rot fungus, mobilized the king's highly (15)N-enriched nutrients, values indicative of a diet rich in meat, to decay wood throughout the tomb. It is also evident from the delta(15)N values of the degraded wood that the nitrogen needed for the decay of many of the artifacts in the tomb came from multiple sources, mobilized at potentially different episodes of decay. The redistribution of nutrients by the fungus was restricted by constraints imposed by the cellular structure of the different wood materials that apparently were used intentionally in the construction to minimize decay.

Archaeology↗
PubMed1995

Observation of the internal configuration of rat incisor odontoblasts by scanning electron microscopy using the AODO method.

The internal configuration of rat incisor odontoblasts was studied mainly by scanning electron microscopy (SEM) using the AODO method (low concentration aldehyde prefixation, osmium tetroxide postfixation, dimethyl sulfoxide (DMSO) freeze-fracture, osmium tetroxide maceration). The present SEM findings were compared with the results obtained by conventional transmission electron microscopy (TEM) of epon-embedded specimens. The following results were obtained: 1) Functioning odontoblasts were characterized by a concentric, laminar rough endoplasmic reticulum (rER) with many long mitochondria interposed. 2) A network of tubular smooth endoplasmic reticulum (sER) was observed in the odontoblast process and distal portion of both functioning and resting odontoblasts. 3) The tubulo-vesicular elements which have been found to present a modified Golgi-GERL organelle with secretory and absorptive functions were demonstrated in both the functioning and resting odontoblasts. Structurally they consist of the sER network and strings of granules and vesicles. 4) Various types of cytoplasmic bodies, e.g., lysosomes, cytosomes and multivesicular bodies, related to the sER were also noted in both functioning and resting odontoblasts. 5) Microapocrine secretion of membranous vesicles of various sizes into the predentin and along the lateral branchings of odontoblast processes in the circumpulpal dentin was observed during the matrix apposition stage of the odontoblasts. The present morphological study revealed the three-dimensional configuration of the intra- and extra-cellular structures related to dentinogenesis by odontoblasts.

Aldehydes↗
PubMed1999

The transduction of very small hydrostatic pressures.

This paper reviews experiments in which cells, subjected to hydrostatic pressures of 20 kPa or less, (micro-pressures), demonstrate a perturbation in growth and or metabolism. Similarly, the behavioural responses of aquatic animals (lacking an obvious compressible gas phase) to comparable pressures are reviewed. It may be shown that in both cases the effect of such very low hydrostatic pressures cannot be mediated through the thermodynamic mechanisms which are invoked for the effects of high hydrostatic pressure. The general conclusion is that cells probably respond to micro-pressures through a mechanical process. Differential compression of cellular structures is likely to cause shear and strain, leading to changes in enzyme and/or ion channel activity. If this conclusion is true then it raises a novel question about the involvement of 'micro-mechanical' effects in cells subjected to high hydrostatic pressure. The responses of aquatic animals to micro-pressures may be accounted for, using the model case of the crab, by the mechanical, bulk, compression of hair cells in the statocysts, the organ of balance. If this is true, it raises the interesting question of why the putative cellular mechanisms of micro-pressure transduction appear to have been superseded by the statocyst.

Adaptation, Physiological↗
PubMed1992

Poly(A) RNA codistribution with microfilaments: evaluation by in situ hybridization and quantitative digital imaging microscopy.

The distribution of poly(A) RNA has been visualized in single cells using high-resolution fluorescent in situ hybridization. Digital imaging microscopy was used to quantitate the signal in various cellular compartments. Most of the poly(A) signal remained associated with the cellular filament systems after solubilization of membranes with Triton, dissociation of ribosomes with puromycin, and digestion of non-poly(A) RNA with ribonuclease A and T1. The actin filaments were shown to be the predominant cellular structural elements associating with the poly(A) because low doses of cytochalasin released about two-thirds of the poly(A). An approach to assess the extent of colocalization of two images was devised using in situ hybridization to poly(A) in combination with probes for ribosomes, membranes, or F-actin. Digital imaging microscopy showed that most poly(A) spatially distributes most significantly with ribosomes, slightly less with F-actin, and least of all with membranes. The results suggest a mechanism for anchoring (and perhaps moving) much of the cellular mRNA utilizing the interaction between actin filaments and poly(A).

Actin Cytoskeleton↗
PubMed1997

Microtubule-associated protein 2c reorganizes both microtubules and microfilaments into distinct cytological structures in an actin-binding protein-280-deficient melanoma cell line.

The emergence of processes from cells often involves interactions between microtubules and microfilaments. Interactions between these two cytoskeletal systems are particularly apparent in neuronal growth cones. The juvenile isoform of the neuronal microtubule-associated protein 2 (MAP2c) is present in growth cones, where we hypothesize it mediates interactions between microfilaments and microtubules. To approach this problem in vivo, we used the human melanoma cell, M2, which lacks actin-binding protein-280 (ABP-280) and forms membrane blebs, which are not seen in wild-type or ABP-transfected cells. The microinjection of tau or mature MAP2 rescued the blebbing phenotype; MAP2c not only caused cessation of blebbing but also induced the formation of two distinct cellular structures. These were actin-rich lamellae, which often included membrane ruffles, and microtubule-bearing processes. The lamellae collapsed after treatment with cytochalasin D, and the processes retracted after treatment with colchicine. MAP2c was immunocytochemically visualized in zones of the cell that were devoid of tubulin, such as regions within the lamellae and in association with membrane ruffles. In vitro rheometry confirmed that MAP2c is an efficient actin gelation protein capable of organizing actin filaments into an isotropic array at very low concentrations; tau and mature MAP2 do not share this rheologic property. These results suggest that MAP2c engages in functionally specific interactions not only with microtubules but also with microfilaments.

Actin Cytoskeleton↗
PubMed2004

The emergence of competition between model protocells.

The transition from independent molecular entities to cellular structures with integrated behaviors was a crucial aspect of the origin of life. We show that simple physical principles can mediate a coordinated interaction between genome and compartment boundary, independent of any genomic functions beyond self-replication. RNA, encapsulated in fatty acid vesicles, exerts an osmotic pressure on the vesicle membrane that drives the uptake of additional membrane components, leading to membrane growth at the expense of relaxed vesicles, which shrink. Thus, more efficient RNA replication could cause faster cell growth, leading to the emergence of Darwinian evolution at the cellular level.

Biological Evolution↗