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.

SourceResearch connectionFrom yearThrough year

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

At least 1,693 records · Page 94Linked to original sources

PubMedDate not supplied

A fast method for processing biologic material for electron microscopic diagnosis in infectious disease.

A fast method for processing biologic material for electron microscopy for precise and specific diagnosis of infectious agents is an increasing necessity. After different, reportedly fast methods were tested, a useful and quick technique was developed that provides well-preserved cellular structures, enabling the etiologic diagnosis of infectious agents even in necrotic tissue or other biologic material such as sputum, bronchoalveolar lavage, and the like. This procedure takes less than 3 hours.

Acquired Immunodeficiency Syndrome↗

PubMed1984

Application of acrylamide as an embedding medium in studies of lectin and antibody binding in the vertebrate retina.

The use of acrylamide as an embedding medium for vertebrate retinal tissue and its applicability to lectin and antibody-based cytochemical studies is described. The acrylamide technique has numerous advantages over those using fresh-frozen or paraffin embedded material. The morphological integrity of retinal tissue prepared in acrylamide is equivalent to that obtainable with paraffin and superior to that of fresh-frozen material. In addition, this technique alleviates problems often encountered with the thermal and chemical treatments required in the paraffin method. The acrylamide technique allows the localization of lectin and antibody-binding sites essentially unaltered by the fixation and embedding protocol, as in frozen sections, while maintaining tissue morphology similar to that of paraffin-embedded tissue. It is hoped that this approach will be useful to other workers in vision research employing lectin, antibody or other cytochemical approaches to the study of cellular structure and function.

Acrylamide↗

PubMed1991

Air/liquid corneal organ culture: a light microscopic study.

Air/liquid organ culture of tissues with stratified epithelial layers has been shown to encourage tight packing of cells and promote cellular differentiation. In this study human corneas cultured in a air/liquid environment were compared to paired, conventionally-cultured corneas to determine if the long-term morphology could be improved. Fourteen paired human corneas were cultured at 37 degrees C in covered culture dishes for 1 to 3 weeks. Air/liquid cultured corneas were placed epithelial-side up in a fixed position and culture medium was added to a level so that during rocking the corneal epithelia were intermittently exposed to air/liquid environments. Mate corneas were cultured using the conventional method. In this method corneas are fully submerged, epithelial-side down, in culture medium. After 3 weeks of culture significantly less epithelial intercellular edema was noted for the air/liquid cultures (p = 0.033), compared to conventional cultures. Significant improvements in cellular structure of the endothelial layers, after 1 and 3 weeks incubation (p = 0.029 and 0.000) and stromal layers, after 3 weeks in culture (p = 0.024), were also noted. We have shown that slight modifications of the organ culture environment lead to improvements in corneal morphology. Air/liquid corneal organ culture has promise for use in corneal wound healing studies and long-term culture.

Aged↗

PubMed1988

Iron-chelating therapy.

Because of the catalytic action of iron in one-electron redox reactions, it has a key role in the formation of harmful oxygen derivatives and production of peroxidative damage to vital cellular structures. The clinical manifestations of iron overload may be prevented and even reversed by the effective administration of the iron-chelating drug deferoxamine (DF). Recent experimental evidence suggests that DF may also be useful in modifying disease conditions unrelated to iron overload by preventing the formation of free radicals, the powerful final effectors of tissue damage resulting from the respiratory burst of granulocytes and macrophages participating in the inflammatory response. Although much experimental work is still needed, this novel approach in iron-chelating therapy may have far-reaching implications in the management of autoimmune disease, adult respiratory distress syndrome, and organ transplantation. The poor intestinal absorption of DF, its almost prohibitive price, and short duration of action underline the need for new, orally effective iron chelators. A number of very promising orally effective drugs have been identified in recent years, such as the polyanionic amines, aryl hydrazones, and hydroxypyridones. Further development for clinical use of this new generation of iron-chelating drugs is a major challenge for future research.

Animals↗

PubMed1999

Fluorescence tracing of intracellular proteins.

Developments in fluorescence microscopy and the availability of fluorescently labeled antibodies and probes for localization of molecules and organelles have made the microscope an indispensable tool with which one can map specific molecules to subcellular loci allowing deep insight into cell and organelle biology. Furthermore, confocal microscopy permits analysis of the three dimensional architecture of cells that could not be accomplished by conventional light microscopy. The goal of fluorescence protein tracing by microscopy is to visualize cellular constituents and general cytoarchitecture as close to native organization as possible. To achieve this, and to preserve cellular structure in the best possible manner, the specimen is usually fixed chemically. Here I review several standard fixation, permeabilization and labeling schemes followed by examples of several standard imaging techniques.

Animals↗

PubMed1995

[Analysis of iodine compounds in young rat skin in the period of suckling and in the adult. Effect of perchlorate].

In the suckling and adult rats equilibrated or no by 125I, cutaneous iodine analysed by dialysis and chromatography techniques (Dowex and Sephadex) was the purpose of this study. Dialysis studies had shown that most of steady or labelled skin iodine had an iodide form (90 to 95% of the total iodine). There were at least two intracellular iodide pools: the first one was quickly dialysable, in fact about 60 percent of initial radioactivity represented the intracellular iodide equilibrated with extracellular fluid. The other one wasn't or was little dialysable representing probably the cutaneous iodide storage compartment. Chromatography studies (Dowex or Sephadex) demonstrated that the skin of the young and adult rat contained T4 and T3 hormones in a small percentage. The iodide represented a value more than 90% of initial total radioactivity. Results concerning kinetic skin iodine, eight and twenty four hours after LT4(125)I injected to adults and to control and iodine deficient ten day old rats, confirmed those obtained here by Dowex chromatography and previous ones. Triiodothyronine (T3) might have an origin either in thyroid synthesis or in deiodination of T4. Consequently we may say that the skin of the 10 day and 14 day old rats presented a great accumulation of iodide. The perchlorate inhibited this storage. Indeed, in young deficient iodine rats at birth, cutaneous iodide concentrations were reduced whereas those of T4 and T3 as well as the ratio T3/T4 haven't been modified. Therefore the iodine deficiency seemed to have a few effects on the skin deiodinating activity. Indeed the skin of iodine deficient immature rat became unable to accumulate iodide. The main effect of the skin iodine deficiency was the inhibition of iodide transport from the extracellular fluid to the intracellular one, but not inside cellular structures.

Animals↗

PubMed1982

Microvascular perfusion and metabolism in injured spinal cord after methylprednisolone treatment.

The purpose of this study was to determine the effect of treatment with the synthetic glucocorticoid, methylprednisolone, on the microvasulature and metabolism of the traumatized spinal cord. Spinal cords of cats were compressed with a 170-gm weight for 5 minutes and were treated with either high-dose methylprednisolone (HDMP, 15 mg/kg/24 hrs) or megadose methylprednisolone (MDMP,60 mg/kg/24 hrs). Animals were sacrificed at 2, 8, or 24 hours following injury. Treatment with HDMP resulted in substantial preservation of injured spinal cord microvascular perfusion at 8 hours as compared with injured untreated cats. Compression trauma caused a partial derangement of energy metabolism and a shift toward anaerobic glycolysis in both treated and untreated groups for the entire 24-hour postinjury period. Tissue levels of adenosine triphosphate, phosphocreatine, and total adenylates in the HDMP-treated cats sacrificed at 8 hours after trauma were significantly elevated over untreated controls, but those in the 2- and 24-hour groups were not. Concentration of energy intermediates in MDMP-treated cat were either equal to or below those of injured untreated animals al all three postinjury time period. The postinjury metabolite pattern and concentrations seen in this study possibly result from differing levels of blood flow and neuronal activity in the injured untreated, HDMP-, and MDMP-treated spinal cords. Better tissue perfusion in the HDMP-treated cats might be expected to result in an improved tissue energy state in these animals. However, intensive high-dose glucocorticoid treatment has been demonstrated to augment spinal cord monosynaptic and polysynaptic reflex transmission and primary afferent excitability. Furthermore, acute single intravenous dose studies have shown this direct neuronal action to be dose-related. Thus, additional high-energy phosphate molecules that may be reformed as a result of HDMP treatment were perhaps used as the energy source for any increased neuronal activity caused by steroid administration. The beneficial effects of glucocorticoid treatment in experimental spinal cord trauma might derive from preserved cellular structural integrity. This could result in increased levels of neuronal activity, energy utilization, and production in treated as compared with untreated tissue.

Animals↗

PubMed2004

Increased expression of focal adhesion kinase in thyroid cancer: immunohistochemical study.

Focal adhesion kinase (FAK) is a tyrosine kinase that is found in cellular structures called focal adhesions. FAK appears to be a key element in signal transduction pathways involved in cell adhesion and locomotion. FAK is overexpressed in various tumors, including tumors derived from regions of the head and neck, colon, breast, prostate, and liver. In this study, we investigated immunohistochemically whether FAK expression was increased in thyroid cancers. FAK staining was not seen in any of the 20 normal thyroid tissues or the 6 nodular hyperplasia specimens. In contrast, FAK staining was observed in all of 17 papillary carcinomas, 9 follicular carcinomas, 8 medullary carcinomas, and 2 anaplastic carcinomas. Nine of 17 follicular adenomas showed FAK immunoreactivity. FAK was not expressed in normal tissue and nodular hyperplasia, but was expressed in some of the follicular adenoma, and all of the follicular, papillary, medullary and anaplastic thyroid carcinoma. This result indicates that the up-regulation of FAK may play a role in the development of thyroid carcinogenesis.

Adenoma↗

PubMed1976

Replication of herpesvirus of turkeys in chick fibroblasts.

An ultrastructural study of chick embryo fibroblasts infected with herpesvirus of turkeys (HVT) revealed that infection produced degenerative effects in the cells ranging from alteration of cellular structures to complete lysis of the cells. Infection was indicated by margination of the nuclear chromatin, the presence of nuclear and cytoplasmic virions, destruction of mitochondria, loss of rough and smooth endoplasmic reticulum, and polykaryocytosis. Viruses entered the cell by penetrating the cytoplasmic membrane, and replication took place within the nucleus. Small nuclear particles observed as aggregates in the presence of few herpesvirions appeared to be a part of the replication of the virus. Viruses were released from the cell nucleus either naked or enveloped. Where karyolysis occurred, naked viruses were released as the karyoplasm diffused into the cytoplasm. Enveloped viruses were not observed leaving the nucleus, but it appeared that departure could have occurred by the budding of the viruses through the nuclear membrane. Where complete lysis of the cells occurred, the naked viruses were released into the extracellular fluid. Enveloped viruses were observed only in intact cells. Viruses which were observed extracellularly were naked viruses, and those that were observed entering the cell by penetrating the cytoplasmic membrane were also naked. This evidence suggests that in vitro HVT does not require the envelope to be infective.

Animals↗

PubMed2005

[Dyes, indispensable tools for the 19th century's biologic and therapeutic revolution].

Born from growing organic chemistry laboratories, dyes were extensively used par textile industry before to be applied in field of biology and therapeutics. Besides their interest for diagnostic techniques due to cell visualization (Virchow, Papanicolaou), dyes allowed scientists to propose scientific hypothesis founding, in conjunction with new microscopy tools, modern basis for biology : tissue constitution, cellular and sub cellular structure, s.o. One of the brightest illustrations of these progresses is the birth of neuronal theory which due to silver print of brain tissue allowed to see intimacy of cerebral structures et propose an operating scheme (Golgi, Cajal). Therapeutic progresses born from dyes chemistry are multiple. First concentrated on the research of antimalarial drugs (Ehrlich) following the use of methylene blue, then generally, anti-infectious drugs, they gave birth to various chimiotherapeutic families: antiseptics, antiparasitic drugs, antibacterial, among which one of the most spectacular illustrations remain sulphonamides preparation.

Anti-Infective Agents↗

PubMed2004

Protein kinase C-dependent activation of P44/42 mitogen-activated protein kinase and heat shock protein 70 in signal transduction during hepatocyte ischemic preconditioning.

AIM: To investigate the significance of protein kinase C(PKC), P44/42 mitogen-activated protein kinase (MAPKs) and heat shock protein (HSP)70 signal transduction during hepatocyte ischemic preconditioning. METHODS: In this study we used an in vitro ischemic preconditioning (IP) model for hepatocytes and an in vivo model for rat liver to investigate the significance of protein kinase C (PKC), P44/42 mitogen-activated protein kinase (P44/42 MAPKs) and heat shock protein 70 (HSP70) signal transduction in IP. Through a normal liver cell hypoxic preconditioning (HP) model in which cultured normal liver cells were subjected to 3 cycles of 5 min of incubation under hypoxic conditions followed by 5 min of reoxygenation and subsequently exposed to hypoxia and reoxygenation for 6 h and 9 h respectively. PKC inhibitor, activator and MEK inhibitor were utilized to analyze the phosphorylation of PKC, the expression of P44/42 MAPKs and HSP70. Viability and cellular ultrastructure were also observed. By using rat liver as an in vivo model of liver preconditioning (3 cycles of 10-min occlusion and 10-min reperfusion), in vivo phosphorylation of PKC and P44/42MAPKs, HSP70 expression were further analyzed. AST/ALT concentration, cellular structure and ultrastructure were also observed. All the data were statistically analyzed. RESULTS: Similar results were obtained in both in vivo and in vitro IP models. Compared with the control without IP (or HP), the phosphorylation of PKC and P44/42 MAPKs and the expression of HSP70 were obviously increased in IP (or HP) treated model in which cytoprotection could be found. The effects of preconditioning were mimicked by stimulating PKC with 4beta phorobol-12-myristate13-acetate (PMA). Conversely, inhibiting PKC with chelerythrine abolished the protection given by preconditioning. PD98059, inhibitor of MEK (the upstream kinase of P44/42MAPKs), also reverted the cytoprotection exerted by preconditioning. CONCLUSION: The results demonstrate that preconditioning induces a rapid activation of P44/42MAPKs and PKC activation plays a pivotal role in the activation of P44/42 MAPKs pathway that participates in the preservation of liver cells. HSP expression is regulated by signals in PKC dependent P44/42 MAPKs pathway.

Animals↗

PubMed2003

Virulence of water-induced coccoid Helicobacter pylori and its experimental infection in mice.

AIM: To explore the virulence and the infectivity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to sterile tap water. METHODS: Three strains of H. pylori, isolated from gastric biopsy specimens of confirmed peptic ulcer, were converted from spiral into coccoid form by exposure to sterile tap water. Both spiral and coccoid forms of H. pylori were tested for the urease activity, and the adherence to Hep-2 cells. The presence of flagella was examined under electron microscopy. In the experimental animal infection, the spiral and coccoid forms of H. pylori originated from the same strain F49 were inoculated intragastrically into BALB/c mice respectively four times at a 3-day interval. Half of the mice from each group were sacrificed at Day 21 and Day 28 after the last inoculation. Histology and H. pylori colonization were detected by urease test of gastric mucosa, cultures of H. pylori, and electron microscopy and so on. RESULTS: The urease activity and the ability of adherence to Hep-2 cells were found to be lower in coccoid H. pylori than that in its spiral form. For example, the transformation in strain F(44) led to a significant decrease of the adherence rate and adherence index from 70.0+/-5.3 % to 30.2+/-3.5 % (P<0.01), and from 2.6+/-0.4 to 0.86+/-0.3 (P<0.01), respectively. The flagella of coccoid H. pylori were observed under electron microscope. In the experimental infection in mice, the positive rate of gastric mucosa urease test was 93.8 % (15/16) in the group infected by spiral H. pylori and 50 % (8/16) in the group infected by coccoid H. pylori, and the estimated coccoid H. pylori colony number was 1.75 vs 0.56. The positive rates of H. pylori culture were 87.5 % (14/16) in spiral H. pylori group and 68.8 % (11/16) in coccoid H. pylori group. There was no significant difference in either urease test or bacterial culture rate between the groups examined at Day 21 and Day 28 after inoculation. Electron microscopic examination of the samples taken from both groups showed the adherence of H. pylori in spiral, bacillary and coccoid shapes to the epithelial cells of gastric wall. Histological examination showed the occurrence of gastric mucosal injury as indicated by various degrees of erosion, ulcer, and inflammatory cell infiltration. Mucosal injury was slighter in the mice infected by coccoid H. pylori. No positive result was obtained in the control group that received intragastrical administration of sterile tap water. CONCLUSION: Although the virulence of coccoid H. pylori induced by water decrease, coccoid H. pylori still remains a considerable urease activity and the adhering ability to epithelial cells. Furthermore, the flagella, an important component responsible for bacterial movement and infection, were still observed as a cellular structure of coccoid H. pylori under electron microscope. The coccoid H. pylori induced by water is capable of colonizing in gastric mucosa and causing gastrititis in mice.

Animals↗

PubMed1999

Antibodies to the cytoplasm, cell membrane and nuclear membrane of malignant neoplasms in pooled normal human polyspecific immunoglobulin G.

IVIg is a preparation of normal polyspecific IgG obtained from pooled plasma of a large number of healthy donors. IVIg treatment of patients with chronic lymphocytic leukemia induced a reduction in the total number of lymphocytes in the peripheral blood. Regression of Kaposi's sarcoma was also noted in an HIV patient treated with IVIg. The aim of this study was to determine whether F(ab')2 prepared from IVIg binds to cellular structures of different tumor tissues. Biotinylated F(ab')2 was prepared from 3 different preparations of IVIg and from affinity purified IgG from a patient with multiple myeloma. Direct immunohistochemistry using a streptavidin peroxidase staining method was performed on biopsy samples of 18 different tumor tissues. Positive staining of the cytoplasm, cell membrane and nuclear membrane of several types of malignant tumors by F(ab')2 from IVIg was immunohistochemically demonstrated. Nuclear staining of tumor cells by IVIg was rare. IVIg bound to different tumors of epithelial origin, especially colon carcinoma, breast carcinoma and squamous cell carcinoma of the lung. Malignant tumors of mesenchymal origin such as leiomyosarcoma have also demonstrated positive staining by IVIg. IVIg contains antibodies to the cytoplasm, nuclear membrane and cell membrane of different malignant tumors especially of epithelial origin. This binding might provide a basis for the assumption that IVIg treatment of cancer patients may induce antibody dependent cell mediated cytotoxicity response against tumors, and implies that it can be potentially beneficial as adjuvant treatment of malignant diseases.

Antibody Affinity↗

PubMedDate not supplied

Up-regulation of beta-actin, cyclophilin and GAPDH in N1S1 rat hepatoma.

Beta-actin, cyclophilin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) are all constantly expressed proteins that regulate cellular structures and endogenous cytoarchitectural functions. In this study, we used an in vivo N1S1 rat hepatoma model to examine changes in the expression levels of these housekeeping genes in normal and tumor liver samples. The beta-actin, cyclophilin and GAPDH genes were all up-regulated in tumor groups as compared to the controls. Our results suggest that up-regulation of beta-actin, cyclophilin and GAPDH genes may be essential for oncogenesis in hepatoma.

Actins↗

PubMed1999

Changes in the evolution of the antigenic profiles and morphology during coccoid conversion of Helicobacter pylori.

OBJECTIVES: The significance of the coccoid forms of H. pylori is still controversial and the questions of whether these forms are viable and infective or degenerative are still open. We induced conversion from rod to coccoid forms and studied morphological changes and antigenic evolutions during this conversion and, thereby, elucidated the viability of coccoid forms. METHODS: The H. pylori strain (C001) used for Western blotting was isolated from the patient with gastric cancer. The antigenic evolution during coccoid conversion of H. pylori was studied by Western blotting, using different sera from thirty patients known to be culture positive. These sera were used to reveal the total antigens of the strain cultured for 2 days (100% rod) and 15 days (> 99% coccoid). After SDS-PAGE, with 10% separating gel of total antigens (rod and coccoid), transblotting (Trans-Blot electrophoretic cell, Bio-Rad) was taken onto a nitrocellulose membrane (Bio-Rad). Then, the blots, with human sera diluted at 1/100, were developed with color reaction by goat serum anti-human IgG with alkaline phosphatase and BCIP. RESULTS: The antigenic profiles were not changed in 46.7% (14/30 cases) and were changed in 53.3% (16/30 cases) during coccoid conversion. Antigenic fractions changed during coccoid conversion were protein band at 120 kDa and band at 35 kDa, and were not detected in coccus forms. The rest of the profiles were identical between rod and coccoid forms. The protein which disappeared include CagA (120 kDa) and porin, or adhesin (35 kDa). The morphological changes during coccoid conversion were U shaped at day 7, doughnut shaped at day 9 and full coccoid at day 15. CONCLUSIONS: The results showed that coccoid forms of H. pylori retain cellular structures similar to rod form, and some of the antigens (CagA and porin) disappeared during coccoid conversion. Therefore, coccoid form might be viable and represent one of the stages of H. pylori biological cycle.

Adaptation, Physiological↗

PubMed2006

[Oxidative stress in critically ill patients].

Among critically ill patients, several physio-pathological processes such as global and local hypo-perfusion, hypoxia, endothelial injury and acidosis have been associated with the production and release of large amounts of reactive oxygen species (ROS) in a non regulated fashion. Although in physiologic conditions ROS influence intracellular processes and participate in the defense against infectious organism, in critically ill conditions they are associated with potential oxidative damage over cellular structures and with persistent activation of the inflammatory response. Mechanisms associated with oxidative damage are activation of the macrophage-monocyte system and neutrophils, ischemia-reperfusion events and intracellular ROS production. Endogenous compounds, mainly enzymes, and dietary components act as antioxidant. Several studies show that in critically ill patients increase levels of ROS or reduction of antioxidant levels are related to disease severity. In animal models of critical diseases, antioxidant therapy has shown to reduce mortality. Nevertheless, there are few studies in humans that only show improvements in hemodynamic variables, reduction in inflammatory mediators levels, decreases in oxidized compounds and that suggest a lower incidence of multiple organ failure.

Antioxidants↗

PubMed2001

Detection of heat injury in Listeria monocytogenes Scott A.

Methods of detecting live pathogens in foods that may be growth inhibited following heat treatment are essential to food safety. Among the techniques available, reverse transcription polymerase chain reaction (RT-PCR) amplification of messenger RNA from heat-injured Listeria monocytogenes Scott A is preferable to direct PCR in an attempt to avoid false positives from dead cells. The RT-PCR has a detection limit of 3 x 10(6) CFU/g, compared to 3 CFU/g for untreated controls, but may not be suitable for the identification of all viable cells. Physically apparent changes in cellular structures from heat injury in L. monocytogenes are expected to result. Ultrastructural analyses did depict notable heat damage as cytoplasmic clearing after 5 min at 60 degrees C. The heat-injured survivors can be readily distinguished from total viable cells using selective media. As a result, combinations of molecular and visual methods including selective media improve detectability of heat-injured, viable L. monocytogenes Scott A.

Colony Count, Microbial↗

PubMed2005

Dissecting Nck/Dock signaling pathways in Drosophila visual system.

The establishment of neuronal connections during embryonic development requires the precise guidance and targeting of the neuronal growth cone, an expanded cellular structure at the leading tip of a growing axon. The growth cone contains sophisticated signaling systems that allow the rapid communication between guidance receptors and the actin cytoskeleton in generating directed motility. Previous studies demonstrated a specific role for the Nck/Dock SH2/SH3 adapter protein in photoreceptor (R cell) axon guidance and target recognition in the Drosophila visual system, suggesting strongly that Nck/Dock is one of the long-sought missing links between cell surface receptors and the actin cytoskeleton. In this review, I discuss the recent progress on dissecting the Nck/Dock signaling pathways in R-cell growth cones. These studies have identified additional key components of the Nck/Dock signaling pathways for linking the receptor signaling to the remodeling of the actin cytoskeleton in controlling growth-cone motility.

Actins↗