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PubMed1983

Characterization of human serum spreading factor with monoclonal antibody.

Serum spreading factor is a glycoprotein isolated from human serum that promotes spreading of a variety of cell types on culture dishes. We developed mouse hybridoma lines secreting monoclonal antibody to serum spreading factor that markedly inhibited the rate of serum spreading factor-promoted spreading of both fibroblastic and epithelial cells in culture. Fibronectin-promoted cell spreading was unaffected by monoclonal antibody to serum spreading factor, and the factor appeared to be distinct by several criteria from fibronectin or laminin. Human serum-promoted cell spreading was partially inhibited by monoclonal antibody to serum spreading factor. The antibody recognized primarily two forms of serum spreading factor that migrated in NaDodSO4/polyacrylamide gel electrophoresis in a manner consistent with molecular weights of 65,000-70,000 and 75,000-78,000. In addition to being found in plasma, serum spreading factor was also found associated with washed human platelets.

Animals↗
PubMed1996

Intracellular pH regulation during spreading of human neutrophils.

The regulation of the intracelluar pH (pHi) during spreading of human neutrophils was studied by a combination of fluorescence imaging and video microscopy. Spreading on adhesive substrates caused a rapid and sustained cytosolic alkalinization. This pHi increase was prevented by the omission of external Na+, suggesting that it results from the activation of Na+/H+ exchange. Spreading-induced alkalinization was also precluded by the compound HOE 694 at concentrations that selectively block the NHE-1 isoform of the Na+H+ antiporter. Inhibition of Na+/H+ exchange by either procedure unmasked a sizable cytosolic acidification upon spreading, indicative of intracellular acid production. The excess acid generation was caused, at least in part, by the activation of the respiratory burst, since the acidification closely correlated with superoxide production, measured in single spreading neutrophils with dihydrorhodamine-123, and little acid production was observed in the presence of diphenylene iodonium, a blocker of the NADPH oxidase. Moreover, neutrophils from chronic granulomatous disease patients, which do not produce superoxide, failed to acidify. Comparable pHi changes were observed when beta 2 integrins were selectively activated during spreading on surfaces coated with anti-CD18 antibodies. When integrin engagement was precluded by pretreatment with soluble anti-CD18 antibody, the pHi changes associated with spreading on fibrinogen were markedly reduced. Inhibition of microfilament assembly with cytochalasin D precluded spreading and concomitantly abolished superoxide production and the associated pHi changes, indicating that cytoskeletal reorganization and/or an increase in the number of adherence receptors engaged are required for the responses. Neutrophils spread normally when the oxidase was blocked or when pHi was clamped near physiological values with nigericin. Spreading, however, was strongly inhibited when pHi was clamped at acidic values. Our results indicate that neutrophils release superoxide upon spreading, generating a burst of intracellular acid production. The concomitant activation of the Na+/H+ antiport not only prevents the deleterious effects of the acid released by the NADPH oxidase, but induces a net cytosolic alkalinization. Since several functions of neutrophils are inhibited at an acidic pHi, the coordinated activation of pHi regulatory mechanisms along with the oxidase is essential for sustained microbicidal activity.

Actin Cytoskeleton↗
PubMed2000

Phosphorylated pleckstrin induces cell spreading via an integrin-dependent pathway.

Pleckstrin is a 40-kD phosphoprotein containing NH(2)- and COOH-terminal pleckstrin homology (PH) domains separated by a disheveled-egl 10-pleckstrin (DEP) domain. After platelet activation, pleckstrin is rapidly phosphorylated by protein kinase C. We reported previously that expressed phosphorylated pleckstrin induces cytoskeletal reorganization and localizes in microvilli along with glycoproteins, such as integrins. Given the role of integrins in cytoskeletal organization and cell spreading, we investigated whether signaling from pleckstrin cooperated with signaling pathways involving the platelet integrin, alphaIIbbeta3. Pleckstrin induced cell spreading in both transformed (COS-1 & CHO) and nontransformed (REF52) cell lines, and this spreading was regulated by pleckstrin phosphorylation. In REF52 cells, pleckstrin-induced spreading was matrix dependent, as evidenced by spreading of these cells on fibrinogen but not on fibronectin. Coexpression with alphaIIbbeta3 did not enhance pleckstrin-mediated cell spreading in either REF52 or CHO cells. However, coexpression of the inactive variant alphaIIbbeta3 Ser753Pro, or beta3 Ser753Pro alone, completely blocked pleckstrin-induced spreading. This implies that alphaIIbbeta3 Ser753Pro functions as a competitive inhibitor by blocking the effects of an endogenous receptor that is used in the signaling pathway involved in pleckstrin-induced cell spreading. Expression of a chimeric protein composed of the extracellular and transmembrane portion of Tac fused to the cytoplasmic tail of beta3 completely blocked pleckstrin-mediated spreading, whereas chimeras containing the cytoplasmic tail of beta3 Ser753Pro or alphaIIb had no effect. This suggests that the association of an unknown signaling protein with the cytoplasmic tail of an endogenous integrin beta-chain is also required for pleckstrin-induced spreading. Thus, expressed phosphorylated pleckstrin promotes cell spreading that is both matrix and integrin dependent. To our knowledge, this is the first example of a mutated integrin functioning as a dominant negative inhibitor.

Animals↗
PubMed1979

Induction of spreading during fibroblast movement.

This paper describes the phenomenon of retraction-induced spreading of embryonic chick heart fibroblasts moving in culture. Measurable criteria of cell spreading (increase in area of the spreading lamella, and total spread area of the cell) are found to change predictably with retraction of a portion of the cell margin. Ruffling activity was found to increase. The leading lamella of a spread fibroblast ordinarily advances slowly, with an average area increase of approximately 21 mu2m/min. A 10- to 30-fold increase in spreading occurs within 8 s after onset of retraction at the trailing edge and then decreases slightly so that by 1 min the increase in spreading is five to tenfold. During this period, there is a linear relationship between area increase at the leading edge and area decrease at the trailing edge. During the next 10--15 min, spreading gradually decreases to normal. Although the relationship between area spreading and area retracting of fibroblasts at different phases of movement is not significantly linear, it is highly correlated (Table II). These results suggest that the rate of fibroblast spreading may be inversely related to the degree of spreading of the cell as a whole.

Animals↗
PubMed2002

A spread enriched with plant sterol-esters lowers blood cholesterol and lipoproteins without affecting vitamins A and E in normal and hypercholesterolemic Japanese men and women.

The objective of the study was to investigate whether different initial baseline cholesterol levels modulate the efficacy of a spread enriched with plant sterol-esters (PS) in lowering blood cholesterol in a Japanese population consuming their usual diet. Healthy adults with a mean age of 45 y and mean plasma total cholesterol (TC) level of 6.5 mmol/L were recruited to participate in a double-blind trial comprised of a run-in period of 1 wk, followed by two intervention periods of 3 wks in a 2 x 2 crossover design and a post-trial follow-up of 3 wk. Volunteers consumed two spreads, one enriched with PS (12 g/100 g plant sterols) and a control spread not fortified with PS. Recommended spread intake was 15 g/d. Effects on plasma lipids, lipoproteins, beta-carotene and vitamins A and E were assessed. Plasma TC and LDL cholesterol (LDL-C) concentrations were 5.8 and 9.1% lower, respectively, when subjects consumed the PS spread than when they consumed the control spread (P < 0.001). Subjects were divided into two groups [normal and mildly cholesterolemic (TC <5.7 mmol/L) and hypercholesterolemic (TC >/= 5.7 mmol/L)]. Reductions (P < 0.001) in TC and LDL-C due to treatment in the former group were 4.9 and 7.9%, respectively. In the hypercholesterolemic group, the reductions (P < 0.001) were 7.1 and 10.6%, respectively. The decreases did not differ between normal/mildly cholesterolemic and hypercholesterolemic subjects. Plasma apolipoprotein B (apoB) and remnant-like particle (RLP) cholesterol (RLP-C) concentrations were lower when subjects consumed the PS spread (44.3 g/L) than the control spread (49.7 g/L). Plasma beta-carotene concentration was lower (P < 0.001) in subjects consuming the PS spread than in the control. Changes in plasma vitamins A and E levels did not differ after intake of the PS and control spreads. In conclusion, consumption of a PS-enriched spread effectively lowered plasma TC, LDL-C, apoB and RLP-C regardless of baseline plasma TC at an intake of 1.8 g/d of plant sterols.

Adult↗
PubMed2004

Assessing the risk of invasive spread in fragmented landscapes.

Little theoretical work has investigated how landscape structure affects invasive spread, even though broad-scale disturbances caused by habitat loss and fragmentation are believed to facilitate the spread of exotic species. Neutral landscape models (NLMs), derived from percolation theory in the field of landscape ecology, provide a tool for assessing the risk of invasive spread in fragmented landscapes. A percolation-based analysis of the potential for invasive spread in fragmented landscapes predicts that invasive spread may be enormously enhanced beyond some threshold level of habitat loss, which depends upon the species' dispersal abilities and the degree of habitat fragmentation. Assuming that invasive species spread primarily through disturbed areas of the landscape, poor dispersers may spread better in landscapes in which disturbances are concentrated in space, whereas good dispersers are predicted to spread better in landscapes where disturbances are small and dispersed (i.e., fragmented landscape). Assessing the risk of invasive spread in fragmented landscapes ultimately requires understanding the relative effects of landscape structure on processes that contribute to invasive spread--dispersal (successful colonization) and demography (successful establishment). Colonization success is predicted to be highest when >20% of the landscape has been disturbed, particularly if disturbances are large or aggregated in space, because propagules are more likely to encounter sites suitable for colonization and establishment. However, landscape pattern becomes less important for predicting colonization success if species are capable of occasional long-distance dispersal events. Invasive species are also more likely to persist and achieve positive population growth rates (successful establishment) in landscapes with clumped disturbance patterns, which can then function as population sources that produce immigrants that invade other landscapes. Finally, the invasibility of communities may be greatest in landscapes with a concentrated pattern of disturbance, especially below some critical threshold of biodiversity. Below the critical biodiversity threshold, the introduction of a single species can trigger a cascade of extinctions among indigenous species. The application of NLMs may thus offer new insights and opportunities for the management and restoration of landscapes so as to slow the spread of invasive species.

Animals↗
PubMed2006

Herpes simplex virus gE/gI must accumulate in the trans-Golgi network at early times and then redistribute to cell junctions to promote cell-cell spread.

Herpes simplex virus (HSV) glycoprotein heterodimer gE/gI is necessary for virus spread in epithelial and neuronal tissues. Deletion of the relatively large gE cytoplasmic (CT) domain abrogates the ability of gE/gI to mediate HSV spread. The gE CT domain is required for the sorting of gE/gI to the trans-Golgi network (TGN) in early stages of virus infection, and there are several recognizable TGN sorting motifs grouped near the center of this domain. Late in HSV infection, gE/gI, other viral glycoproteins, and enveloped virions redistribute from the TGN to epithelial cell junctions, and the gE CT domain is also required for this process. Without the gE CT domain, newly enveloped virions are directed to apical surfaces instead of to cell junctions. We hypothesized that the gE CT domain promotes virus envelopment into TGN subdomains from which nascent enveloped virions are sorted to cell junctions, a process that enhances cell-to-cell spread. To characterize elements of the gE CT domain involved in intracellular trafficking and cell-to-cell spread, we constructed a panel of truncation mutants. Specifically, these mutants were used to address whether sorting to the TGN and redistribution to cell junctions are necessary, and sufficient, for gE/gI to promote cell-to-cell spread. gE-519, lacking 32 C-terminal residues, localized normally to the TGN early in infection and then trafficked to cell junctions at late times and mediated virus spread. By contrast, mutants gE-495 (lacking 56 C-terminal residues) and gE-470 (lacking 81 residues) accumulated in the TGN but did not traffic to cell junctions and did not mediate cell-to-cell spread. A fourth mutant, gE-448 (lacking most of the CT domain), did not localize to cell junctions and did not mediate virus spread. Therefore, the capacity of gE/gI to promote cell-cell spread requires early localization to the TGN, but this is not sufficient for virus spread. Additionally, gE CT sequences between residues 495 and 519, which contain no obvious cell sorting motifs, are required to promote gE/gI traffic to cell junctions and cell-to-cell spread.

Animals↗
PubMed2000

Autocrine human growth hormone enhancement of human mammary carcinoma cell spreading is Jak2 dependent.

We investigated the role of autocrine production of human (h) GH in the attachment and spreading of mammary carcinoma cells in vitro. We used a previously described model system for the study of the autocrine/paracrine role of GH in which the hGH gene (MCF-hGH) or a translation-deficient hGH gene (MCF-MUT) was stably transfected into MCF-7 cells. No differences in attachment to a collagen matrix between MCF-hGH and MCF-MUT cells were observed in either serum-free medium (SFM) or medium containing exogenous hGH, 5% serum, or 10% serum. In contrast, MCF-hGH cells spread more rapidly on a collagen matrix than did MCF-MUT cells. Exogenous hGH and 10% serum interacted with autocrine production of hGH in an additive manner to increase cell spreading. MCF-hGH cells formed filipodia and stress fibers earlier than MCF-MUT cells during the process of cell spreading and possessed marked differences in morphology after spreading. MCF-MUT cells displayed uniform and symmetrical formation of stress fibers, whereas MCF-hGH cells displayed irregular and elongated stress fiber formation. The level of cytoplasmic phosphotyrosine was increased in MCF-hGH compared with MCF-MUT cells during spreading and displayed colocalization with Janus kinase 2 (JAK2). Basal JAK2 tyrosine phosphorylation was increased, and it increased further on spreading in MCF-hGH cells compared with MCF-MUT cells. Transient transfection of JAK2 complementary DNA resulted in interaction with autocrine hGH to increase the rate of cell spreading in MCF-hGH cells compared with MCF-MUT cells. Treatment with a selective JAK2 tyrosine kinase inhibitor (AG 490) reduced the rate of MCF-hGH cell spreading to the rate of MCF-MUT cell spreading. Thus, we conclude that autocrine production of hGH enhances the rate of mammary carcinoma cell spreading in a JAK2-dependent manner.

Actins↗
PubMed1993

Shelf-life of pasteurized process cheese spreads made from cheddar cheese manufactured with a nisin-producing starter culture.

Cheddar cheese made with a nisin-producing starter culture and Cheddar cheese made with a commercially available starter culture were used to manufacture pasteurized process cheese spreads at low and high moisture percentages (53 and 60%, respectively). Composition did not differ between spreads of similar moisture content with and without nisin. The nisin contents of cheese spreads were 301 and 387 IU/g at the high and low moisture percentages, respectively. Nisin was not inactivated by the thermal process used during cheese spread manufacture. Shelf-life of pasteurized process cheese spreads was determined during storage at 22 and 37 degrees C. Low moisture cheese spreads with nisin had a longer shelf-life than corresponding cheese spreads without nisin when cheeses were incubated at either temperature. High moisture cheese spreads with nisin had a longer shelf-life than control spreads when cheeses were incubated at 22 degrees C. However, shelf-life did not differ between high moisture spread with nisin and cheese spreads without nisin when cheeses were incubated at 37 degrees C.

Cheese↗
PubMed2001

The vasodilator-stimulated phosphoprotein is regulated by cyclic GMP-dependent protein kinase during neutrophil spreading.

The expression and phosphorylation state of the vasodilator-stimulated phosphoprotein (VASP), a membrane-associated focal adhesion protein, was investigated in human neutrophils. Adhesion and spreading of neutrophils induced the rapid phosphorylation of VASP. The phosphorylation of VASP was dependent on cell spreading, as VASP was expressed as a dephosphorylated protein in round adherent cells and was phosphorylated at the onset of changes in cell shape from round to spread cells. Immunofluorescence microscopy demonstrated that VASP was localized at the cell cortex in round cells and redistributed to focal adhesions at the ventral surface of the cell body during cell spreading. Dual labeling of spread cells indicated that VASP was colocalized with F-actin in filopodia and in focal adhesions, suggesting that the phosphorylation of VASP during cell spreading may be involved in focal adhesion complex organization and actin dynamics. VASP is a prominent substrate for both cGMP-dependent protein kinase (cGK) and cAMP-dependent protein kinase. Evidence suggested that cGK regulated neutrophil spreading, as both VASP phosphorylation and neutrophil spreading were inhibited by Rp-8-pCPT-cGMPS (cGK inhibitor), but not KT5720 (cAMP-dependent protein kinase inhibitor). In contrast, neutrophil spreading was accelerated when cGMP levels were elevated with 8-Br-cGMP, a direct activator of cGK. Furthermore, the same conditions that lead to VASP phosphorylation during neutrophil adherence and spreading induced significant elevations of cGMP in neutrophils. These results indicate that cGMP/cGK signal transduction is required for neutrophil spreading, and that VASP is a target for cGK regulation.

Cell Adhesion↗
PubMed1990

[The effect of injection speed and needle gauge on the spread of sensory blockade in spinal anesthesia].

Unanimity has not yet been reached on the influence of injection speed and needle size on the spread of sensory blockade in spinal anesthesia. While McClure et al. [6] proved that a change in injection speed had no effect on the spread of the blockade, Lanz et al. [4] showed in their investigation that increasing injection speed increases the spread of the blockade. The influence of needle size has hardly been investigated so far. Moore et al. [7] report that the needle size alone has no effect on the spread of the blockade. In this study the influence of injection speed and that of needle size on spread of sensory blockade were considered separately. MATERIALS AND METHODS. Spinal puncture was performed via the midline approach at the L3-4 interspace with the patient in a sitting position. Immediately after the induction of anesthesia the patients were placed in the supine position again. As local anesthetic 15 mg (3 ml) bupivacaine 0.5% with epinephrine 1:200000 was administered. The aim of the study was to find out how far injection speed and size of the spinal needle influenced the sensory spread in isobaric spinal anesthesia. The height of sensory blockade was assessed by means of the pin-prick method in the midline, and the onset of analgesia was determined as height of spread. The injection speeds for the local anesthetic solution were 0.25, 0.5 and 1 ml per second. The needle sizes were 22, 25, and 29 gauge. Each group consisted of 15 patients. RESULTS. It turned out that slow (0.25 ml/s) and the fast (1 ml s) injection was associated with a significantly higher level of analgesia than the medium one (0.5 ml/s). Cephalad spread was to T7 in the first two groups, while the medium injection speed only achieved a level of T9. The results are statistically significant (P less than 0.05). The comparison of different needle sizes (22, 25, and 29 gauge) used for spinal anesthesia showed a higher spread of the sensory blockade with increased diameter of the spinal needle given a constant injection speed. With the 22-gauge needles (n = 15) sensory blockade extended on average to T7, with 25-gauge needles (n = 15) to T9, and with 29-gauge needles (n = 15) to T10. It has to be mentioned, however, that with the 29-gauge needle the standard injection speed of 0.5 ml/s could not be achieved because of the small inner diameter. The differences between 22- and 25-gauge needles are statistically significant (P less than 0.05). DISCUSSION. No direct relation could be proved between the different injection speeds and the spread of the blockade. Our results are hardly comparable with those of other investigators, since other groups have used different local anesthetics or performed investigations in vitro. The use of large spinal needles is associated with spread of the spinal block to a significantly higher level than is achieved with thinner needles.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1994

Oligomannosides initiate cell spreading of laminin-adherent murine melanoma cells.

Murine melanoma cells readily bind and spread on murine laminin. Uncoupling of spreading from adhesion occurs when unglycosylated laminin is used as the cellular substratum; spreading is restored by soluble glycosylated laminin or soluble glycopeptides of laminin. In this study, using kifunensine, we produced and characterized an oligomannoside-rich glycoform of laminin. When used as a substratum for cell attachment and spreading, this laminin was as effective as mature glycosylated laminin. When added in solution to unglycosylated laminin-adherent cells, kifunensine-laminin was more effective in promoting cell spreading than mature glycosylated laminin. Reconstitution with soluble polysaccharides showed that cell spreading was initiated rapidly by microgram amounts of mannan but not other polysaccharides and approached a maximum within 1 h; titration with mannan yielded an adsorption isotherm profile. Mannose was an antagonist, preventing mannan from restoring cell spreading, but it was not an agonist. A Pronase digest of mature glycosylated laminin, depleted of its oligomannoside-peptides, was unable to restore cell spreading, whereas a control digest was fully active. Melanoma cells were unable to bind to three different neoglycoprotein surfaces, but when soluble unglycosylated laminin was present in the medium the cells adhered to and spread only upon mannosylated bovine serum albumin. Of the various cell lines known to interact with glycosylated laminin only murine melanoma cells showed oligomannoside-dependent spreading on an unglycosylated laminin substratum. The composite results indicate that oligomannosides are necessary to initiate murine melanoma cell spreading on laminin but are not sufficient for cell adhesion.

Alkaloids↗
PubMed1989

Acrylamide sensitization of the heat response of the cytoskeleton and cytotoxicity in attaching and well-spread synchronous Chinese hamster ovary cells.

The vimentin intermediate filament (VIMF) network is more sensitive to heat-induced disruption than either the microtubule (MT) or microfilament (MF) cytoskeletal (CSK) arrays in G1 Chinese hamster ovary (CHO) cells (Coss and Wachsberger: Radiation Research, 1987). We therefore investigated the effect of the VIMF disruptive agent, acrylamide (Eckert: European Journal of Cell Biology 37:169-174, 1985), on the heat response of synchronous CHO cells. Cells, either in the process of spreading (G1 or S phase) or in the well-spread state (S phase), were exposed to a nontoxic concentration of 5 mM acrylamide, heated, and processed for immunofluorescence microscopy 30 min or 20 hr following the heat shock. Recovery from CSK disruption was related to cell survival. CHO cells, either in the process of spreading or in the well-spread state, were sensitized to heat-induced CSK disruption and cytotoxicity by acrylamide. Recovery from CSK disruption correlated with surviving fractions of cells treated in the G1 phase but not with surviving fractions of cells treated in the S phase and was independent of the degree of cell spreading. This correlation suggests that damage to CSK structures may contribute to the death of cells treated in G1 but not necessarily to the death of cells treated in S phase. The degree of acrylamide sensitization of heat-induced CSK disruption was greater for cells exposed to acrylamide prior to spreading than for well-spread cells. Furthermore, normal spreading of cells was prevented when they were plated into medium containing acrylamide, suggesting that acrylamide interferes with the initial stages of attachment and spreading of these cells. These observations are interpreted in relation to the possible role that VIMFs, together with cortical MFs, may play in mediating cell surface focal contacts in the initial stages of cell attachment and spreading.

Acrylamides↗
PubMed1993

Contact inhibition of cell spreading: a mechanism for the maintenance of thyroid cell aggregation in vitro.

When freshly isolated porcine thyroid cells are stimulated with thyrotropin (TSH) they organize to form functional follicles in conventional substrate-adherent culture. Cell aggregation is essential for follicular reorganization and is likely to be influenced by the balance between cell-cell adhesion (promoting aggregation) and cell-substrate adhesion (favoring spreading and monolayer formation). Recently we observed that TSH potentiated cell-cell adhesion and in the present study we have sought evidence that TSH might also regulate cell-substrate adhesion. Two parameters of cell-substrate adhesion, namely, cell attachment to collagen and cell spreading upon collagen, were measured using preparations of isolated single cells and of multicellular aggregates. TSH had no effect upon the attachment or spreading of single cells, but inhibited aggregate spreading without affecting aggregate attachment. The possibility that cell-cell contact modulated the response to TSH in aggregates, but not in single cells, was confirmed using a cell-free membrane preparation which inhibited the spreading of single cells but not their rate of attachment. Moreover, TSH potentiated the inhibitory effect of membranes on the spreading of single cells. Heparin also specifically inhibited the spreading of both single cells and cell aggregates, suggesting that a heparin-sensitive adhesive mechanism might be recruited as thyroid cells spread. We conclude that thyroid cell-substrate adhesion is regulated by a synergistic interaction between cell-cell contact and TSH which preferentially inhibited cell spreading but not attachment. Such contact-dependent inhibition of cell spreading is predicted to preserve cell aggregates and hence contribute to the maintenance of thyroid follicular differentiation in vitro.

Animals↗
PubMed1979

Human serum and epithelial spread in tissue culture.

The dependence of epithelial spread on human serum in culture has been studied. Using measured pieces of mouse ear skin epithelial outgrowth about floating explants (epiboly) and from adherent explants was studied. Where compared directly the two systems show similar results. Because of its ease of quantitation, the adherent explant culture was studied in greater detail. In this system in the presence of serum appreciable spread was found only after 48 h but spread continued for at least the next 4 days. In the absence of serum only minimal epithelial spread occurred. Adding serum to deficient media enhanced spreading and removing serum from media depressed spreading. The extent of spread appeared independent of mouse age for the first 4-10 weeks though 2-week-old mouse skin showed quantitatively greater spreading. The activity in human serum responsible for epithelial spread acts under conditions of minimal DNA synthesis and is not reproduced by bovine serum albumin, fetuin, or serum that had been exposed to 100 degrees C for 5 min. The activity is not dialyzable and it is resistant to the protease inhibitors DFP and PMSF. These studies suggest that a specific serum component(s) serves to support epithelial spread in vitro.

Age Factors↗
PubMed1980

Stimulation of spreading of trypsinized human fibroblasts by lysozymes from Staphylococcus aureus, hen egg white, and human urine.

The effect of lysozyme from three different sources--Staphylococcus aureus, hen egg white, and human urine--on adhesion to substrate and spreading of trypsinized human fibroblasts was studied. Several fibroblast strains were tested under various conditions. It was found that the different cell strains did not show the same capability of spreading and stably attaching to substrates when resuspended in media not containing serum. Some strains did not spread, whereas others spread even in the absence of serum. Cell spreading in these strains did not occur when the cells were pregrown for 5 weeks in media supplemented with 1% fetal bovine serum. Lysozyme from S. aureus allowed stable adhesion to substrate and spreading of all the fibroblast strains unable to elongate in nonsupplemented minimal essential medium. This enzyme accelerated and augmented spreading of the strains capable of elongating in the absence of serum. S. aureus lysozyme also allowed spreading and stable adhesion to substrates of all these strains when they were pregrown for 5 weeks in the presence of 1% fetal bovine serum. Furthermore, hen egg white lysozyme and the lysozyme purified from human urine were both capable of stimulating anchorage to substrate and spreading of trypsinized fibroblasts although their effect was less pronounced than that of the S. aureus lysozyme. Some tentative hypotheses for the mechanism of cell spreading in the presence of lysozyme are made. The possibility that lysozymes, virtually ubiquitous enzymes, may play a specific role in nature in the regulation of cell differentiation and tissue development is finally raised and discussed in light of several previous observations and findings.

Animals↗
PubMed2006

The requirements for herpes simplex virus type 1 cell-cell spread via nectin-1 parallel those for virus entry.

Herpes simplex virus type 1 (HSV-1) spreads from an infected cell to an uninfected cell by virus entry, virus-induced cell fusion, and cell-cell spread. The three forms of virus spread require the viral proteins gB, gD, and gH-gL, as well as a cellular gD receptor. The mutual requirement for the fusion glycoproteins and gD receptor suggests that virus entry, cell fusion, and cell-cell spread occur by a similar mechanism. The goals of this study were to examine the role of the nectin-1alpha transmembrane domain and cytoplasmic tail in cell-cell spread and to obtain a better understanding of the receptor-dependent events occurring at the plasma membrane during cell-cell spread. We determined that an intact nectin-1alpha V-like domain was required for cell-cell spread, while a membrane-spanning domain and cytoplasmic tail were not. Chimeric forms of nectin-1 that were non-functional for virus entry did not mediate cell-cell spread regardless of whether they could mediate cell fusion. Also, cell-cell spread of syncytial isolates was dependent upon nectin-1alpha expression and occurred through a nectin-1-dependent mechanism. Taken together, our results indicate that nectin-1-dependent events occurring at the plasma membrane during cell-cell spread were equivalent to those for virus entry.

Animals↗
PubMed2000

Incremental reduction of serum total cholesterol and low-density lipoprotein cholesterol with the addition of plant stanol ester-containing spread to statin therapy.

This study compares the effect of plant stanol ester spread with a placebo spread on cholesterol in patients taking statin therapy, but who still had elevated low-density lipoprotein (LDL) cholesterol. This was a randomized, double-blind, placebo-controlled clinical trial, with 67 women and 100 men with LDL cholesterol >/=130 mg/dl and triglycerides </=350 mg/dl who had been taking a stable dose of a statin drug for at least 90 days before the start of the study. For 8 weeks, participants consumed 3 servings/day of the plant stanol ester spread that provided 5.1 g/day of plant stanol ester or a placebo. The addition of plant stanol ester spread significantly reduced total cholesterol and LDL cholesterol at 2, 4, and 8 weeks when compared with placebo spread. Plant stanol ester spread reduced total cholesterol at 8 weeks by 12% compared with a placebo reduction of 5% (-7% difference; p <0.0001). Plant stanol ester spread reduced LDL cholesterol at 8 weeks by 17% compared with a 7% reduction in the placebo group (-10% difference, p <0.0001). The absolute reduction in LDL cholesterol at 8 weeks was 24 and 10 mg/dl in the stanol ester and placebo groups, respectively. The plant stanol ester spread group also had greater reductions in both serum total cholesterol and LDL cholesterol than the placebo group at 2 and 4 weeks (p <0.001 for all comparisons). Both spreads were well tolerated by study participants, and no significant adverse events were noted. Consumption of spread that provided 5.1 g/day of plant stanol esters effectively reduced elevated total and LDL cholesterol levels in participants on a stable regimen of a statin.

Administration, Oral↗