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At least 1,207 records · Page 67Linked to original sources
PubMed1979

Mechanisms of cellular adhesion. IV. Role of serum glycoproteins in fibroblast spreading on glass.

We have investigated the exogenous factors required for the transition from the round shape of suspended fibroblasts to the characteristic spread shape on serum-coated glass. Following the evidence of others that the transition is facilitated by adsorbed component(s) related to CIG/LETS (cold-insoluble globulin/large external transformation-sensitive) proteins, we have isolated 2 such preparations from chick serum. Their influence has been investigated on fibroblast adhesion, spreading and growth and they have been characterized by gel electrophoresis, immunological cross-reactivity, amino acid and carbohydrate residue analysis, sedimentation velocity behaviour and circular dichroism spectroscopy. The preparations have molecular weights of 225/215,000 and 140,000 Daltons respectively and are closely similar in composition and secondary structure. The 225/215 000 Dalton doublet is probably a product of limited proteolysis which almost certainly occurred in the avian circulation. For cells seeded on glass precoated in different ways and in different supplemented media we could detect no change in the extent of attachment but there were profound influences on cell shape following this initial adhesion. We confirm that prior adsorption of either CIG-related preparation to glass does indeed promote fibroblast spreading in the absence of other serum components and that CIG is the sole serum component with this type of activity. We now add 2 important qualifications: (i) the presence of substrate-adsorbed serum CIG is not essential for spreading when other serum components are present in the medium; and (ii) the adhesive organization shown by interference reflexion microscopy is incompletely formed unless the additional serum components are present in the medium. We therefore conclude that 16C fibroblasts have the ability when given the stimulus of soluble serum components other than CIG, but not otherwise, to synthesize all the components necessary for the highly organized contacts with glass, including endogenous CIG/LETS proteins.

Amino Acids↗
PubMed1981

Surface changes during retraction-induced spreading of fibroblasts.

Retraction of the trailing edge of an embryonic chick heart fibroblast results in an abrupt increase in protrusive activity at the leading edge of the cell. This increase was studied with time-lapse cinemicrography and scanning electron microscopy. Increased spreading following retraction results primarily from an increase in the duration of the extension phase of lamellipodial spreading. Much ruffling accompanies this increased spreading, particularly during its earliest phase. Upon retraction of the trailing edge, folds appear on the surface of the retracted tail and adjacent cell body and, soon after, microvilli-like structures appear as well. Once the moving cell has fully respread, however, the upper surface is once again smooth and free of folds and microvilli. Artificial detachment of a spreading lamella with a microneedle, and its consequent retraction, also causes increased protrusive activity of the remaining lamellae of the cell. These results are consistent with the hypothesis that retraction of one part of the cell makes surface membrane and cytoplasm available for forming protrusions elsewhere.

Animals↗
PubMed1986

Monensin and tunicamycin-induced inhibition of HT29 cell spreading and growth.

HT29 cells originating from a human colon adenocarcinoma, spread very rapidly after seeding on their own extracellular matrix (ECM). Preincubation of cells with the inhibitor of protein glycosylation tunicamycin (TM) or with the ionophore monensin substantially suppressed cell spreading in serum-free medium without affecting cell adhesion to ECM. Addition of the drugs after cell attachment and spreading inhibited cell growth. TM-treated cells remained viable after 6 days of exposure to 2 micrograms ml-1 of TM and resumed their normal growth rate and shape after removing the drug from the medium. On the contrary, monensin inhibition of cell growth was not reversible: after 3 days, cells detached from the ECM and were unable to exclude Trypan Blue. At the ultrastructural level, a swollen Golgi apparatus with numerous vacuoles was observed after treatment for 2 h in either TM or monensin-preincubated cells. These results suggest that TM and monensin interfere with the insertion and, or, function of one or more cell surface glycoproteins, possibly interacting with cytoskeleton and involved in cell spreading and growth.

Adenocarcinoma↗
PubMed1990

Substratum-induced stress fiber assembly in vascular endothelial cells during spreading in vitro.

We tested whether aortic endothelial cell (EC)-synthesized substrata, which modulate smooth muscle cell proliferation and EC motility following injury, could influence EC actin cytoskeleton and spreading in vitro. A partial characterization of the substrata indicates that the substratum prepared by deoxycholic acid extraction (DOC-derived substratum) is enriched with fibronectin and type IV collagen. Substratum prepared by removal of the intact monolayer with 20 mM EGTA in PBS (EGTA-derived substratum) contains fibronectin and heparan sulfate proteoglycan, but no type IV collagen. Morphometric analyses were performed on fixed and cytoskeletal antibody treated EC in order to quantitate the extent of spreading and stress fiber (SF) assembly. Compared to plastic, the DOC-derived substratum, a collagenase-treated DOC-derived substratum (CT-DOC-derived substratum) and the EGTA-derived substratum promote EC spreading 2.3-, 2.9- and 1.7-fold, respectively. In addition, there are 4.2-, 4.1- and 2.0-fold more SF on DOC-, CT-DOC- and EGTA-derived substrata, respectively, when compared to plastic. Subcellular fractionation and immunoprecipitation of cytoskeletal proteins from metabolically labeled EC were performed prior to electrophoresis and fluorography. The DOC-derived substratum increases immunoprecipitable actin and myosin 3- to 4.5-fold in both fractions compared to the EGTA-derived substratum and plastic. Collagenase treatment of the DOC-derived substratum partially inhibits this increase. Cycloheximide treatment prevents the rise in soluble actin and myosin as well as causing a reduction in SF number by 1/2 on the DOC-derived substratum and 2/3 on CT-DOC-derived substratum. We propose that fibronectin-collagen interactions are, in part, responsible for inducing endothelial synthesis of cytoskeletal proteins required for SF assembly. This substratum-induced actin-cytoskeletal reorganization facilitates EC spreading in vitro.

Actins↗
PubMed2005

Insulinoma cell line (MIN6) adhesion and spreading mediated by Arg-Gly-Asp (RGD) sequence conjugated in thermo-reversible gel.

We have functionalized gels with a putative cell-binding (-Arg-Gly-Asp-) (RGD) domain in an effort to regulate mammalian cell behavior in cells entrapped with gel. Adhesion molecules composed of Gly-Arg-Gly-Asp-Ser (GRGDS) peptides and cell recognition ligands were inculcated into thermo-reversible hydrogel composed of N-isopropylacrylamide, with a small amount of succinyl poly(ethylene glycol) (PEG) acrylate (MW 2000) used as a biomimetic extracellular matrix (ECM). The GRGDS-containing p(NiPAAm-co-PEG) copolymer gel was studied in vitro for its ability to promote cell spreading and to increase the viability of cells by introducing PEG spacers. Hydrogel lacking the adhesion molecules proved to be a poor ECM for adhesion, permitting only a 20% spread of the seeded cells after 10 d. When PEG spacer arms, immobilized by a peptide linkage, had been integrated into the hydrogel, conjugation of RGD promoted cell spread by 300% in a 28-d trial. In addition, in a serum-free medium, only GRGDS peptides conjugated with the spacer arm were able to promote cell spread.

Adsorption↗
PubMed1995

Reconsidering a paradigm: the spread of supraglottic carcinoma to the glottis.

This study was performed to evaluate the spread of supraglottic carcinoma to the glottic level. Whole organ sections of total laryngectomy specimens from 37 patients with previously untreated supraglottic carcinomas were reviewed retrospectively. Of the 37 specimens, 20 (54%) were noted to have extension of cancer to the glottic level. A significant relationship was noted between glottic extension and abnormal cord motion (P = .0002). A statistically significant trend was noted for the relationship between inferior extension along the supraglottic mucosa and glottic level extension (P < .0001). Contrary to the prevailing model of the spread of supraglottic carcinoma, in which there is a distinct barrier to spread at the ventricle, this analysis of selected supraglottic carcinomas revealed a continuum of spread from the supraglottic to the glottis.

Chi-Square Distribution↗
PubMed2003

Mode analysis of spreading of partially coherent beams propagating through atmospheric turbulence.

The spreading of partially coherent beams propagating through atmospheric turbulence is studied by use of the coherent-mode representation of the beams. Specifically, we consider partially coherent Gaussian Schell-model beams entering the atmosphere, and we examine the spreading of each coherent mode, represented by a Hermite-Gaussian function, on propagation. We find that in atmospheric turbulence the relative spreading of higher-order modes is smaller than that of lower-order modes, whereas the relative spreading of all order modes is the same as in free space. This modal behavior successfully explains why under certain circumstances partially coherent beams are less affected by atmospheric turbulence than are fully spatially coherent laser beams.

Journal Article↗
PubMed2000

Fine-needle aspiration cytologic technique for lung cancer has a high potential of malignant cell spread through the tract.

BACKGROUND: Fine-needle aspiration cytologic technique (FNAC), a method to detect malignancy for undetermined pulmonary nodules, may have a high potential to spread malignant cells from the tumor to the pleural cavity. OBJECTIVE: The authors assessed malignant cell spread through the needle tract following FNAC for peripheral lung carcinoma. MATERIALS AND METHODS: Lung lobes resected from 20 patients during the treatment of lung carcinoma were examined. The visceral pleura over the lung carcinoma was irrigated by heparinized saline solution to clean the surface, and then irrigated before FNAC and irrigated following FNAC to collect cells on the visceral pleura. FNAC was performed once for each tumor. Papanicolau's method was employed for cytologic examination. RESULTS: There were 15 specimens of adenocarcinoma, 4 specimens of squamous cell carcinoma, and 1 specimen of atypical carcinoid. The maximum diameter of the specimens ranged from 10 to 60 mm (median, 25 mm). Pleural indentation was observed in 15 samples. All results of FNAC were positive and matched the histologic diagnosis. Pre-FNAC specimens revealed a positive malignancy rate of 10% (2 of 20), but post-FNAC specimens had a rate of 60% (12 of 20; p = 0.002) CONCLUSION: FNAC has the potential to spread malignant cells to the pleural space. Further study is needed to determine the clinical significance of the spread of malignant cells in the pleural space.

Adenocarcinoma↗
PubMed1979

Inhomogeneous spread of excitation in canine Purkinje fibers.

Spread of excitation in isolated canine bundle branches was examined by microelectrode technique in order to investigate the possibility of dissociated impulse transmission in normal Purkinje fibers. In all experiments, local excitation of the preparation evoked either by fine bipolar extracellular electrodes or an intracellular microelectrode proceeded much faster along the longitudinal axis of the fibers than along the transverse axis. As a result, the spread of excitation in the vicinity of stimulating site showed significantly inhomogeneous character. The inhomogeneity of excitation spread became more manifest with more eccentric location of the stimulating site in a given preparation. Larger preparation showed greater degree of inhomogeneity. Nevertheless, the inhomogeneous spread of excitation alone appeared unlikely to provide multiply pathways which were functionally dissociated with each other. When premature stimulation was applied, however, different conductivity among fibers within a single false tendon was oberved, suggesting that each conducting element became more independent.

Animals↗
PubMed2004

Progesterone receptor A and B expression and progestagen treatment in growth and spread of endometrial cancer cells in nude mice.

In endometrial cancer, decreased expression of progesterone receptor (PR) isotypes A and B (PRA and PRB) is a feature of poorly differentiated tumours. In distant metastases, PRB is the predominantly expressed isotype and endometrial cancer cells that express PRB have been observed to be more invasive. Furthermore, PRB-associated in vitro invasion is markedly inhibited by progestagens. In the present study, ovariectomized mice were injected intraperitoneally with Ishikawa endometrial cancer cells that express only PRA, only PRB, both PRA and PRB, or no PR. Half of the mice were substituted with medroxyprogesterone acetate (MPA). After ten weeks, growth and spread of the cancer cells were examined macroscopically, microscopically, and by PCR detection. Without MPA substitution, cells that express only PRB were found to be the most proliferative and migrative, while cells that express only PRA, both receptor isotypes, or no PR, showed minimal growth and spread. MPA appeared to inhibit growth and spread of PR-positive cells. Surprisingly, when mice that were inoculated with PR-negative cells were substituted with MPA, this resulted in massive abdominal tumour growth. These results provide further evidence that over-expression of PRB in endometrial cancer contributes to the development of a more aggressive phenotype. MPA inhibits tumour growth and spread of PR-positive cells, but can also have an indirectly stimulating effect on PR-negative tumour cells, probably through a host-mediated response.

Animals↗
PubMed1984

Effect of parathyroid hormone and calcitonin on the cytoplasmic spreading of isolated osteoclasts.

Osteoclasts, the major agents of bone resorption, were isolated from neonatal rat bone, and the cytoplasmic spreading of these cells was measured after incubation in the presence or absence of hormones or other cell types. Salmon calcitonin, which inhibits osteoclastic bone resorption, reduced spreading in a dose-dependent manner and caused significant inhibition at concentrations as low as 6.7 pg/ml. Parathyroid hormone (PTH) had no effect on the spreading of isolated osteoclasts but if osteoblasts and osteoclasts were co-cultured the addition of PTH caused a marked increase in spreading at concentrations of 0.025 i.u./ml and above. The results suggest that while calcitonin is a direct inhibitor of osteoclastic activity, PTH may stimulate osteoclasts through a primary action on osteoblasts.

Animals↗
PubMed1985

Intracortical spread of neuronal activities induced by stimulation of recurrent and thalamic afferent pathways compared with epicortical activation.

In the encéphale isolé cat preparation the cerebral peduncle (CP) and the nucleus ventralis lateralis (VL) of the thalamus were stimulated. Short-latency responses recorded from precruciate cortical neurons consisted of excitatory (EPSP) and inhibitory postsynaptic potentials (IPSP). Laminar distributions of these responses and their latencies wee viewed as the spatiotemporal pattern of spread of excitation and inhibition within the cortex in comparison with those obtained by epicortical stimulation (EPICS). In contrast with activities by EPICS spreading downwards from superficial to deep layers, CP recurrent activities spread upwards from deep to middle or superficial layers, and those by VL afferents spread from middle to both superficial and deep layers bidirectionally. These three intracortical routes shared common cell assemblies in that they received convergent EPSPs or IPSPs to various extents from different inputs. The routes for EPICS and VL inputs were overlapped particularly with abundant supply of convergence in spite of their functional difference. Relevant potentiality of the cerebral network in forming plural patterns was discussed.

Afferent Pathways↗
PubMed2002

Tendon involvement in pedal infection: MR analysis of frequency, distribution, and spread of infection.

OBJECTIVE: The objective of our study was to evaluate the frequency, distribution, and extent of tendon involvement in patients with pedal infections. MATERIALS AND METHODS: Contrast-enhanced MR imaging examinations of 159 infected feet performed at 1.5 T were reviewed by two musculoskeletal radiologists for the presence and location of tendon infection (peritendinous enhancement contiguous to an adjacent ulcer or cellulitis) and for the spread of infection along tendons, which was defined as peritendinous contrast enhancement extending more than 2 cm beyond surrounding cellulitis. The study group was composed of 156 consecutive patients, 82.7% of whom had diabetes; all patients underwent subsequent surgical treatment. Results of MR evaluations were compared with the patients' charts and surgical reports. RESULTS: Of the 129 MR examinations showing an infection in the forefoot, MR evidence of tendon involvement in the infection was observed in 56 MR examinations (43%). The sum of involved tendons per ray was as follows: first ray (flexor tendon, n = 19; extensor tendon, n = 13), second (flexor tendon, n = 12; extensor tendon, n = 7), third (flexor tendon, n = 5; extensor tendon, n = 4), fourth (flexor tendon, n = 5; extensor tendon, n = 1), and fifth (flexor tendon, n = 11; extensor tendon, n = 6). Of the 32 MR examinations showing infection in the hindfoot, 14 examinations (44%) showed evidence of tendon involvement, most frequently of the distal Achilles tendon (n = 7). MR evidence of the spread of infection along a tendon was seen in 12 examinations, always with proximal spread of infection; and infection led to the development of an abscess in the central plantar compartment in three patients. Intraoperative evidence of a tendon infection was documented in 11 patients. The surgical procedure was altered because of the tendon infection in six patients. CONCLUSION: MR evidence of tendon infection is present in approximately half the patients who require surgery for pedal infection. Evidence of spread of the infection along tendons is seen infrequently on MR imaging. Detection of a tendon infection could influence surgical therapy.

Adult↗
PubMed2006

Blockade of beta1 integrin-laminin-5 interaction affects spreading and insulin secretion of rat beta-cells attached on extracellular matrix.

When attached on a matrix produced by a rat bladder carcinoma cell line (804G matrix), rat pancreatic beta-cells spread in response to glucose and secrete more insulin compared with cells attached on poly-l-lysine. The aim of this study was to determine whether laminin-5 and its corresponding cell receptor beta1 integrin are implicated in these phenomena. By using specific blocking antibodies, we demonstrated that laminin-5 is the component present in 804G matrix responsible for the effect of 804G matrix on beta-cell function and spreading. When expression of two well-known laminin-5 ligands, beta1 and beta4 integrin, was assessed by Western blot and RT-PCR, only the beta1 integrin was detected in beta-cells. Anti-beta1 integrin antibody reduced the spreading of beta-cells on 804G matrix. Blockade of the interaction between beta1 integrins and laminin-5 resulted in a reduction in glucose-stimulated insulin secretion. Blocking anti-beta1 integrin antibody also inhibited focal adhesion kinase phosphorylation induced by 804G matrix. In conclusion, anti-beta1 integrin and -laminin-5 antibodies interfere with spreading of beta-cells, resulting in decreased insulin secretion in response to glucose. Our findings indicate that outside-in signaling via engagement of beta1 integrins by laminin-5 is an important component of normal beta-cell function.

Animals↗
PubMed1997

Effect of extracellular matrix glycation on endothelial cell adhesion and spreading: involvement of vitronectin.

Glycation of proteins of the vessel wall is thought to play an important role in the pathogenesis of vascular complications in diabetes by affecting structure and function of these proteins. Adhesive proteins in the extracellular matrix (ECM) of endothelial cells (ECs) are essential for attachment of ECs to the subintima. In this study, we investigated the effect of glycation of ECM and purified adhesive proteins on EC adhesion and spreading. ECM was incubated with the reactive sugar glucose-6-phosphate (0-500 mmol/l) for different time periods (0-14 days) at 37 degrees C. Degree of glycation, measured in an enzyme-linked immunosorbent assay using a monoclonal antibody specific for advanced glycation end products, increased in a time- and concentration-dependent manner. Glycation of ECM with 50 mmol/l glucose-6-phosphate resulted in increased coverage by ECs as measured in a cell adhesion assay and was the result of an increase in number of adhered cells, while cell size was unaffected. Glycation of ECM with higher concentrations of glucose-6-phosphate resulted in decreased coverage by ECs caused by both a reduction in number of adhered ECs and impaired spreading. Experiments with purified glycated matrix proteins indicate that the decrease in EC adhesion and spreading on glycated ECM may result from glycation of vitronectin. Impaired EC adhesion and spreading caused by vitronectin glycation may result in impaired endothelial function and contribute to vascular disease.

Animals↗
PubMed1993

Amodal completion as another perception of color-spreading stimuli.

We made a solid three-dimensional object of the Redies-Spillmann figure and found two kinds of completely different phenomena. First, transparent color-spreading was observed in the empty space around the object. Second, another perceptual organization occurred: observers perceived a cross as a cross-shaped slit through which to see, and then they perceived spreading color disappear entirely. They reported an apparent opaque occluding surface which was localized at the same depth as the slit but was in fact the background. They also reported a colored circle which was mostly occluded by the surface with a cross-shaped slit. We interpreted the circle as being amodally completed in the sense described by Kanizsa in 1955. Even when the figure was drawn on a piece of paper, we observed these two perceptions. We examined whether other stimuli causing neon color-spreading lead to reports of the perception for the Redies-Spillmann figure and found that all the stimuli we examined led to reports of the same kind of perception. Interestingly, the shape of color-spreading was the same as that of the amodal completion.

Attention↗
PubMed1995

EGF and PGE2: effects on corneal endothelial cell migration and monolayer spreading during wound repair in vitro.

In vivo repair of the adult human corneal endothelium occurs mainly by movement of cells into the wound defect rather than by cell division. Two forms of cell movement contribute to endothelial wound repair: migration of individual cells into the defect and spreading of the confluent monolayer into the wound area. This laboratory has developed a tissue culture model using rabbit corneal endothelial cells pretreated with the mitotic inhibitor 5-fluorouracil to mimic the relatively amitotic state of human corneal endothelium in vivo. This model permits study of the effects of growth factors and other agents on individual cell migration and monolayer spreading in response to wounding. mRNA for epidermal growth factor (EGF) and its receptor has been detected in cultured corneal endothelial cells and EGF receptors have been detected on human corneal endothelial cells in situ, suggesting that this growth factor may act in an autocrine manner. Prostaglandin E2 (PGE2) is synthesized by cultured corneal endothelial cells and is present in relatively high quantity in aqueous humor in response to corneal wounding and to inflammation in the anterior chamber. Although corneal endothelial cells may be exposed to both EGF and PGE2, little is known about their effects on monolayer repair. The current study compared the effects of PGE2 alone, EGF alone, and both agents in combination on individual cell migration and monolayer spreading using the wound model system and also determined the effect of EGF on PGE2 secretion using a commercial immunoassay. A 15 min exposure of wounded cultures to exogenous PGE2 stimulated individual cell migration and suppressed monolayer spreading.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Calculation and application of point spread functions for treatment planning with high energy photon beams.

A general dose calculation method for treatment planning with high energy photon beams, based on folding of the total energy released by primary photons per unit mass, the terma, with a fractional mean energy imparted point spread function is described. A set of point spread functions has been calculated with Monte Carlo technique for energies of primary photons between 100 keV and 20 MeV. Dose distributions have been calculated for a 6 MV bean using the method. The results clearly point out the considerably increased precision and flexibility achieved when calculating photon beam dose distributions from first principles using Monte Carlo generated point spread functions. The point spread functions calculated in this work are available on magnetic tape from the authors.

Humans↗