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At least 649 records · Page 36Linked to original sources
PubMed1987

Epidural pressure and its relation to spread of epidural analgesia.

The relationships between the epidural pressures following the injection of local anesthetic solution and the spread of epidural analgesia were investigated. In 46 patients, 15 ml of 2% mepivacaine was injected into the lumbar epidural space at a constant rate (1 ml/sec) using an electropowered syringe pump. Injection pressures and residual pressures were recorded and the spread of analgesia to pinprick was assessed. The changes of the epidural pressures during and following the injection of a volume of local anesthetic solution in old subjects were significantly smaller than those in young subjects (P < 0.05). The spread of analgesia closely correlated with the epidural pressures during and following the injection of local anesthetic solution. The most close correlation was found between the epidural pressure immediately after the completion of injection and the spread of analgesia (r = -0.5659, P < 0.001). In conclusion, the lower the terminal injection pressure and the residual pressures associated with higher age, the wider the spread of epidural analgesia.

Journal Article↗
PubMed2006

Comparative spatial spread overtime of Zucchini Yellow Mosaic Virus (ZYMV) and Watermelon Mosaic Virus (WMV) in fields of transgenic squash expressing the coat protein genes of ZYMV and WMV, and in fields of nontransgenic squash.

The spatial and temporal patterns of aphid-vectored spread of Zucchini Yellow Mosaic Virus (ZYMV) and Watermelon Mosaic Virus (WMV) were monitored over two consecutive years in plantings of nontransgenic and transgenic squash ZW-20H (commercial cv. Freedom II) and ZW-20B, both expressing the coat protein genes of ZYMV and WMV. All test plants were surrounded by nontransgenic plants that were mechanically inoculated with ZYMV or WMV, and served as primary virus source. Across all trials, none of the transgenic plants exhibited systemic symptoms upon infection by ZYMV and WMV but a few of them developed localized chlorotic dots and/or blotches, and had low mixed infection rates [4% (6 of 139) of ZW-20H and 9% (13 of 139) of ZW-20B], as shown by ELISA. Geostatistical analysis of ELISA positive transgenic plants indicated, (i) a lack of spatial relationship on spread of ZYMV and WMV for ZW-20H with flat omnidirectional experimental semivariograms that fitted poorly theoretical models, and (ii) some extent of spatial dependence on ZYMV spread for ZW-20B with a well structured experimental semivariogram that fitted poorly theoretical models during the first but not the second growing season. In contrast, a strong spatial dependence on spread of ZYMV and WMV was found for nontransgenic plants, which developed severe systemic symptoms, had prevalent mixed infection rates (62%, 86 of 139), and well-defined omnidirectional experimental semivariograms that fitted a spherical model. Geostatistical data were sustained by virus transmission experiments with Myzus persicae in screenhouses, showing that commercial transgenic squash ZW-20H alter the dynamics of ZYMV and WMV epidemics by preventing secondary plant-to-plant spread.

Animals↗
PubMed1985

Transcapsular spread of metastatic squamous cell carcinoma from cervical lymph nodes.

The incidence, extent, and selected clinicopathologic correlations of transcapsular spread from metastatic tumor in the cervical lymph nodes have been investigated in 210 specimens obtained by radical neck dissection from 203 patients with squamous cell carcinomas of the head and neck. Transcapsular spread was detected in 137 of 159 (86 percent) positive specimens, and classified as macroscopic in 74 (54 percent) and microscopic in 63 (46 percent). Macroscopic transcapsular spread was seen most frequently in association with large nodal masses more than 3 cm in diameter (48 of 70 specimens, 69 percent), but also occurred in some specimens with smaller lymph nodes less than 3 cm in diameter (26 of 67 specimens, 39 percent). Anatomic structures most commonly invaded in areas of neck dissection with macroscopic spread from nodal metastases were skeletal muscle (39 dissections) and the adventitial coat of the internal jugular vein (27 dissections). Macroscopic transcapsular infiltration was associated with a high incidence (44 percent) of recurrent tumor in the ipsilateral neck, particularly within 12 months of surgery. Microscopic transcapsular growth was associated with a lower incidence (25 percent) of recurrent tumor in the ipsilateral neck but the difference did not reach statistical significance. Similar recurrence figures (32 percent) were found in the minority of patients whose nodal disease was intracapsular at the time of neck dissection. More precise definition of the morphologic extent of transcapsular spread could be important in clarifying its clinicopathologic correlations.

Adult↗
PubMed1978

Spreading of liposomes at the air/water interface.

Two types of film structure are formed when liposomes are spread at the air/water interface. At zero surface pressure, there is a slow transformation of the closed bilayered structure into a lipid monolayer. The internal content of the liposomes is released into the aqueous subphase. In contrast, when multilamellar liposomes are spread against a surface pressure, they retain their internal content at the air/water interface by forming multilayered structures. Among the liposomes which dipped through the interface an important fraction loses its internal content. During the spreading process at zero surface pressure, it seems that the outer layer of the liposome spreads with a better yield as compared with the inner layer. It is possible to use this spreading technique to determine the asymmetrical distribution of lipids across bilayers.

Air↗
PubMed1984

Alpha-actinin arcs in megakaryocyte spreading.

Cultured megakaryocytes, isolated from guinea pig bone marrow, were treated with buffer or adenosine diphosphate (ADP) (10 microM) on plain or coated glass surfaces. Control cells were rounded and non-adherent. The nucleotide induced the cells to spread to several times the initial diameter, and to become flattened and markedly adherent to the substratum. 'Cytoskeletons' were examined by transmission electron microscopy (TEM). Those from unspread cells contained only rare microfilaments and no filament bundles; those from spread cells contained large numbers of microfilaments in nets and many filament bundles, which were largely oriented circumferentially. Interference reflection microscopy demonstrated that the spread cells were attached to the substratum in arc-shaped regions, which corresponded to arcs containing alpha-actinin as seen by specific immunofluorescence of the same cells. However, other arcs of alpha-actinin staining did not correspond to arcs of tight attachment. We conclude that fibrous arcs, which appear to assemble as part of the spreading process, play a role in what are probably transient surface attachment sites. A survey of observations of spreading in other cell types suggests that similar arcs are more widespread than has been realized.

Actinin↗
PubMed1990

Persistent spreading of ligament cells on osteopontin/bone sialoprotein-I or collagen enhances tolerance to heat shock.

Fibronectin (FN), bone sialoprotein-I (BSP-I), Type I collagen, and a number of synthetic peptides containing the integrin attachment sequence (RDG) were evaluated for their ability to affect stress tolerance in osteo-ligament cells (OL). The attachment and spreading of OL cells was determined by the method of Klebe (1974) and Akiyama et al. (1986). Survival from heat shock was evaluated after the methods of Gerner et al. (1976). These studies showed that FN, BSP-I, and synthetic RGD peptides enhance attachment of OL cells. Increased survival from heat was limited to cells spread on fibronectin, BSP-I, and Type I collagen. OL cells that persistently spread on BSP-I and Type I collagen had more survivors than cells demonstrating transient spreading on FN. These studies indicate that (a) cell spreading is a prerequisite for stress tolerance and (b) enhanced stress tolerance is mediated by protein sequences other than those immediately surrounding the RGD sites in native proteins.

Animals↗
PubMed1991

Spreading of mouse fibroblasts on the substrate with multiple spikes.

Mouse embryo fibroblasts were cultivated on special substrates with discontinuous surfaces. The substrates were silicon plates with multiple vertical (65-90 microns height) spike-like silicon microcrystals evenly distributed on the plate surfaces. It was shown that the cells were successfully spread and flattened on these substrates. The spread cells formed several discrete attachment zones at the tops and side surfaces of the spikes; these zones were separated from one another by distances considerably greater than the diameter of the unspread cell. At early stages of spreading the unspread cells attached to the tops of single spikes and extended long filopodia attached to the distant spikes. At later stages the lamellae were formed between the filopodia: probably these filopodia served as guidelines for extension of lamellae and progressive cell spreading. These experiments demonstrated that continuity of substrate surface is not a necessary condition for advanced cell spreading.

Animals↗
PubMed1989

Analysis of the ligand-promoted global conformational change in aspartate transcarbamoylase. Evidence for a two-state transition from boundary spreading in sedimentation velocity experiments.

A global conformational change in the regulatory enzyme aspartate transcarbamoylase of Escherichia coli was demonstrated 20 years ago by the 3.5% decrease in the sedimentation coefficient of the enzyme upon its interaction with carbamoyl phosphate and saturating amounts of the aspartate analog succinate. This "swelling" of aspartate transcarbamoylase attributable to the T----R allosteric transition was observed also in subsequent studies when the enzyme was completely saturated with the bisubstrate analog N-(phosphonacetyl)-L-aspartate. In neither of these studies was a direct attempt made by an analysis of boundary spreading (expressed as an apparent diffusion coefficient) on partially liganded enzyme to determine whether the solution contained only T and R-state molecules, as expected for a concerted transition, or a mixture of more than two distinct conformational states. The sensitivity of boundary spreading measurements was tested with a known mixture of fully liganded wild-type enzyme (R-state) and an inactive T-state mutant that did not bind either succinate or the bisubstrate ligand. This experiment yielded broad boundaries with an apparent diffusion coefficient about 10% greater than that of T-state enzyme, due to the differential sedimentation of the two independent species. Identical boundary spreading was obtained theoretically by simulating an equimolar mixture of T and R-state aspartate transcarbamoylase. These results proved that the boundary spreading measurement was sensitive to the presence of heterogeneity. Analogous experiments with only wild-type enzyme in the presence of sub-stoichiometric amounts of the tightly bound bisubstrate ligand sufficient to promote a 1.8% decrease in sedimentation coefficient also exhibited broader boundaries, corresponding to a 10% increase in the apparent diffusion coefficient relative to the unliganded enzyme. In contrast, such broad boundaries were not observed in experiments when the weakly bound succinate was present in quantities sufficient to cause the same 1.8% decrease in sedimentation coefficient. The differences in boundary spreading observed with the two active-site ligands were accounted for by the affinities of the respective ligands for the enzyme and the transport theory of a ligand-promoted isomerization of the protein. In the presence of sub-stoichiometric levels of the tight-binding bisubstrate ligand, the dynamic equilibrium between the T and the R-state is essentially uncoupled and the species sediment at slightly different rates to give broad boundaries.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspartate Carbamoyltransferase↗
PubMed1978

Spreading of vascular endothelial cells in culture: spatial reorganization of cytoplasmic fibers and organelles.

The three-dimensional organization and fine structure of cytoplasmic components within whole non-embedded bovine aortic endothelial cells were examined during their attachment and spreading in tissue culture. Cells were cultured directly on Formvar-coated gold grids, fixed in glutaraldehyde and osmium tetroxide, critical point dried and examined by transmission electron microscopy (TEM) using stereoscopic methods, and by scanning electron microscopy (SEM). Reorganization of cytoplasmic structures during cell spreading occurred in four sequential stages: (1) spreading of the plasma membrane and unstructured cytoplasmic matrix; (2) spreading of cytoplasmic fiber systems (microtubules, microfilament bundles and microtrabecular system); (3) alignment of microfilament bundles and formation of radial tracts of microtubules; and (4) centripetal movement of organelles along radial tracts. These stages observed by TEM correlated with progressive degrees of cell flattening as visualized by SEM. These studies demonstrate that a characteristic reorganization of intracellular fiber systems and organelles accompanies the spreading of endothelial cells in culture.

Animals↗
PubMed1994

Pagetoid spread of intratubular germ cell neoplasia into rete testis: a morphologic and histochemical study of 100 orchiectomy specimens with invasive germ cell tumors.

Intratubular germ cell neoplasia (ITGCN) is now considered to be the preinvasive phase of testicular germ cell tumors with the exceptions of spermatocytic seminoma, pure yolk sac tumor, and mature teratoma. Pagetoid spread of ITGGN into rete testis is a common yet unpublished finding in these cases. We reviewed 100 cases of testicular germ cell tumors from the Surgical Pathology service of Parkland Memorial Hospital (Dallas, TX) to evaluate the frequency of this pattern of spread. Additional sections were obtained from selected cases and were stained with anti-placental alkaline phosphatase, anti-low molecular weight keratin (clone AE1), and various lectins to highlight the process. Pagetoid spread of ITGCN into rete testis was identified in 24 of 60 cases (40%) in which histologic sections contained both ITGCN and rete testis. The incidence of pagetoid ITGCN involvement of the rete testis was lower in pure seminoma (seven of 25 cases [28%]) than in testes containing nonseminomatous germ cell tumors (17 of 35 cases [49%]). AE1 stained the epithelial cells of the rete testis but not the cells of the ITGCN, whereas placental alkaline phosphatase stained the neoplastic cells but not the epithelial cells of the rete testis. These stains were useful in delineating two cases in which the pagetoid involvement was so extensive that they were misdiagnosed as invasive seminomas. Pagetoid spread of ITGCN is a relatively common finding in testicular germ cell tumors and rarely can be mistaken for invasive seminoma. Immunohistochemistry can be helpful in distinguishing florid pagetoid spread from invasive seminoma.

Adolescent↗
PubMed1989

The role of platelet prostanoids and dense granule compounds in initial attachment, spreading and aggregation of platelets on collagen substrates.

The role of platelet prostanoids, ADP and 5HT in initial attachment, spreading and aggregation of platelets on collagen substrates (CI, CIII, CIV, CV, CC) was studied. A positive linear correlation was found between thrombi-like aggregate formation on collagen substrates and production of platelet prostanoids. No correlation was established between platelet aggregation and 14C-5HT release. Thrombi-like aggregate formation was completely inhibited by indomethacin and TXA2/PGH2 antagonists (13-APA and BM 13.177). Both 13-APA and BM 13.177 had no effect on platelet spreading, while indomethacin inhibited this process by 25%. The ADP-scavenger system (CP/CPK) inhibited platelet aggregation and spreading by 25-30%. Initial attachment was not influenced by aspirin, indomethacin and CP/CPK. The data obtained indicate that platelet aggregation on collagen substrates is mediated by PGH2 and TXA2 production. These compounds slightly affect the platelet spreading. Both platelet spreading and aggregation on collagen substrates are only partially mediated by ADP and 5HT release. Initial attachment of platelets does not depend on the release reaction and PGH2/TXA2 synthesis.

Adenosine Diphosphate↗
PubMed1991

Spreading of oligomers on polymers.

The successful repair of a composite restoration may depend on the ability of a repair composite to spread on the restoration to be repaired. The purpose of this study was to measure the spreading of four oligomers on their polymers. The oligomers were: ethoxylated bisphenol A dimethacrylate (EB), BisGMA/3EDMA:70/30 (ED), BisGMA-Nupol (NU), and urethane dimethacrylate (UD). Polymer strips were made from these oligomers by light-curing. Spreading was calculated from measurements of the contact angle of the oligomers on the polymers, the surface tension of the oligomers, and the viscosity of the oligomers. In this model system, values of spreading of EB, ED, UD, and NU on oligomer ED were: 2.8, 1.4, 0.24, and 0.0009 cm/s, respectively. The spreading by oligomers EB, ED, and UD on polymer ED was slightly higher than that on polymer UD.

Analysis of Variance↗
PubMed1992

Beliefs about the satiating effect of bread with spread varying in macronutrient content.

Beliefs about the satiating effect of foods varying in contents of proteins, fats, carbohydrates, and fibre were investigated by face-to-face interviews with a random telephone sample of 101 subjects. Respondents were presented with photographs of two slices of bread covered with common spreads. Fibre level was manipulated by using white bread or wholemeal bread. Levels of proteins, fats and carbohydrates were manipulated by using different kinds of spread. Low and high levels of proteins, fats and carbohydrates had similar energy contents. The results showed that protein-rich spreads (lean meat products) and high-fibre (wholemeal) bread were believed to have a strong satiating effect. The satiating effect of high-fat spreads (butter, bacon) was believed to be much smaller, whereas the sweet carbohydrate spreads (jam, honey) were believed to have no satiating effect.

Adult↗
PubMed1994

Distinct effects of thrombospondin-1 and CISP/thrombospondin-2 on adrenocortical cell spreading.

Corticotropin-induced secreted protein (CISP) is a trimeric protein secreted by bovine adrenocortical cells in response to ACTH, that is likely to represent the bovine form of thrombospondin-2 (TSP2). This study was aimed at delineating the respective effects of CISP/TSP2 and TSP1 (thrombospondin-1) on adrenocortical cell attachment and spreading. TSP1 and CISP/TSP2 were found to slightly reduce the attachment of adrenocortical cells to plastic in the presence of serum but exhibited a pronounced differential effect on cell spreading. CISP/TSP2 inhibited adrenocortical cell spreading in a dose-dependent manner (maximal effect with 40 micrograms/ml) whereas TSP1 (up to 100 micrograms/ml) did not influence this process. The inhibition of spreading was observed whether plates were coated with CISP/TSP2 alone or with a mixture of CISP/TSP2 and fibronectin. We suggest that the inhibition of in vitro adrenocortical cell spreading by CISP/TSP2 is indicative of an implication of this protein in the migration of adrenocortical cells in vivo.

Adrenal Cortex↗
PubMed2005

SNARE-mediated trafficking of alpha5beta1 integrin is required for spreading in CHO cells.

In this study, the role of SNARE-mediated membrane traffic in regulating integrin localization was examined and the requirement for SNARE function in cellular spreading was quantitatively assessed. Membrane traffic was inhibited with the VAMP-specific catalytic light chain from tetanus toxin (TeTx-LC), a dominant-negative form (E329Q) of N-ethylmaleimide-sensitive fusion protein (NSF), and brefeldin A (BfA). Inhibition of membrane traffic with either E329Q-NSF or TeTx-LC, but not BfA, significantly inhibited spreading of CHO cells on fibronectin. Spreading was rescued in TeTx-LC-expressing cells by co-transfection with a TeTx-resistant cellubrevin/VAMP3. E329Q-NSF, a general inhibitor of SNARE function, was a more potent inhibitor of cell spreading than TeTx-LC, suggesting that tetanus toxin-insensitive SNAREs contribute to adhesion. It was found that E329Q-NSF prevented trafficking of alpha5beta1 integrins from a central Rab11-containing compartment to sites of protrusion during cell adhesion, while TeTx-LC delayed this trafficking. These results are consistent with a model of cellular adhesion that implicates SNARE function as an important component of integrin trafficking during the process of cell spreading.

Animals↗
PubMed2006

JSAP1 is required for the cell adhesion and spreading of mouse embryonic fibroblasts.

The roles of JSAP1 and JIP1 in cell adhesion and spreading were examined using mouse embryonic fibroblasts (MEFs) deficient in JIP1 (JIP1-KO), JSAP1 (JSAP1-KO), and in both JIP1 and JSAP1 (double-KO), and by using their wild type. After being plated on fibronectin-coated culture plates, wild type MEFs rapidly adhered and differentiated to typical longitudinal fibroblasts in 4 h. JSAP1-KO MEFs showed a similar sequence of adhesion and cell spreading, but their adhesion was weak, and cell spreading sequence proceeded in a delayed manner compared with the wild type. In spreading JSAP1-KO MEFs, adhesion-triggered actin cytoskeleton reorganization and FAK activation proceeded at a slower pace than in wild type MEFs. The cellular properties of double-KO MEFs and JIP1-KO MEFs were similar to those of JSAP1-KO MEFs and wild type MEFs, respectively. These results suggest that JSAP1 plays a role in adhesion and cell spreading by regulating the rapid reorganization of the actin cytoskeleton.

Actins↗
PubMed2004

Chitosan supports the initial attachment and spreading of osteoblasts preferentially over fibroblasts.

The aim of this study was to determine chitosan's effect on osteoblast and fibroblast cell attachment. Mouse MC3T3-E1 osteoblasts and 3T3 fibroblasts were grown in the presence of serum on two commercially available chitosans, Chitosan-H (CH) and Protasan CL212 (PR). Cell attachment and immunofluorescent analysis at various time points were done to analyze initial phenotypic profiles. At 1h, significantly (P<0.05) fewer fibroblasts attached to CH or PR than serum-coated substrates. Osteoblast attachment to the same biopolymers at 1h was significantly greater than those seen with fibroblasts. At 24 h, levels of cell attachment for fibroblasts to both CH and PR significantly increased and were similar to levels seen in osteoblast cultures at both 1 and 24 h. Morphologically, immunofluorescent analysis showed that osteoblasts plated on the biopolymers were attached and beginning to spread at 1h, whereas fibroblasts appeared more rounded. At 24 h, fibroblasts plated on CH or PR revealed a heterogeneous population of round and semi-spread cells. In comparison, osteoblasts displayed phenotypes that were well spread with a developed cytoskeleton. These results suggest that CH and PR support the initial attachment and spreading of osteoblasts preferentially over fibroblasts, and that manipulation of the biopolymer can alter the level of attachment and spreading.

3T3 Cells↗
PubMed2005

QCM-D studies of attachment and differential spreading of pre-osteoblastic cells on Ta and Cr surfaces.

The quartz crystal microbalance with dissipation (QCM-D) technique was employed to characterize initial cell adhesion in terms of attachment and spreading of pre-osteoblastic MC3T3-E1 cells on Ta and Cr surfaces. Evaluation of initial cell adhesion established a correlation between input cell number and the shifts in frequency (f) and dissipation (D). The f-shift was found to be much larger in serum-free medium as compared to a medium including serum; hence, initial cell adhesion was subsequently evaluated in serum-free medium. During the first hour of adhesion, we found a positive correlation between the QCM-D f-shift and the average area of the spread cells, as measured by cryo-scanning electron microscopy (cryo-SEM). Finally, the QCM-D technique was used to study cell adhesion on different metal oxide surfaces. Initial cell adhesion on Ta was found to induce a larger f-shift as compared to Cr, indicating larger spreading of cells on Ta. Cryo-SEM data confirmed that spreading of cells on Cr was on average only two-thirds the spreading on Ta. Our results demonstrate that the QCM-D technique is a versatile technique to quickly distinguish initial cell-surface interactions on different biomaterials.

Animals↗