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PubMed1983

Studies on memory: the cerebral spread of an engram in mice as affected by inhibitors of dopamine beta-hydroxylase.

Bitemporal injections of puromycin that primarily affect the hippocampal-entorhinal areas consistently cause amnesia of maze-learning in mice for 3 days after training but become consistently ineffective if given 6 or more days after training. At these later times, additional puromycin injection sites covering widespread areas of the forebrain are necessary to induce amnesia. These observations are interpreted to indicate that the locus of the engram has become more widespread within the 6-day period. Treatment with inhibitors of dopamine beta-hydroxylase for 3 days following training, retarded the spread of memory from a matter of days to a period of weeks. Repeated treatment with the inhibitors restricted engram spread for about 3 months; again spread was evident about a month after the last treatment. These observations imply that the mechanisms responsible for engram spread are capable of surviving for extraordinarily long periods of time.

Animals↗

PubMed1975

Polar appearance and nonligand induced spreading of measles virus hemagglutinin at the surface of chronically infected cells.

Fixation with glutaraldehyde (GA) and paraformaldehyde (PFA) preserved measles virus hemagglutinin at the surface of chronically infected cells. Cells fixed with PFA but not with GA exhibited hemadsorption with green monkey cells. PFA fixation, in contrast to GA fixation, also preserved the immunogenicity of measles virus hemolysin. These fixatives and the removal of the measles virus hemagglutinin from the cell surface by trypsin enabled studies of the appearance of the hemagglutinin at the surface membrane. Results obtained by immunofluorescence technique and by hemadsorption indicated that measles virus hemagglutinin appeared polarly at the cell membrane and then spread around the surface. This was substantiated by measurements of the immunofluorescence intensity at the single cell level per membrane unit and per cell, and by measuring the binding of iodinated immunoglobulins per 10(6) cells. The appearance was inhibited by sodium azide and cytochalasin B. The spreading was not inhibited by sodium azide, but was influenced by cytochalasin B. The spreading did not proceed at 4 degrees C. On the basis of these findings, a hypothetical model for appearance and spreading of measles virus hemagglutinin was proposed.

Antibodies, Viral↗

PubMed1988

Cell-substratum interactions: serum spreading factor.

We have prepared a fraction of commercial fetal calf serum whose major component comprises proteins of apparent molecular mass 65-80 kDa. These preparations elicit cell spreading responses in serum-free medium at concentrations similar to those reported for human vitronectin. In addition, we have identified (by a protein blotting technique) the 65-80 kDa component as the active species in our preparations. Cell spreading responses in the presence of our 'bovine vitronectin' preparations are similar to cell spreading on fetal calf serum. (In contrast, cell spreading on bovine fibronectin showed very different kinetics). Our results suggest that bovine vitronectin may be an important component of fetal calf serum involved in conditioning cell culture substrata.

Animals↗

PubMed1993

Relationship between 3T3 cell spreading and the strength of adhesion on glass and silane surfaces.

Cell detachment by laminar shear stresses was used to characterize cellular interactions with hydrophilic glass and hydrophobic silane. In this study, we examined whether smaller, rounder cells were preferentially detached by laminar flow, and whether cell detachment occurred by dissociation of adhesion proteins and their membrane receptors or rupture of the membrane. Shear-induced detachment from glass and silane were similar after 0.5 h static attachment to the surfaces, even though 3T3 cells had a greater projected area on silane. No particular cell size was preferentially detached by fluid shear stresses. After 2 h attachment and spreading, 3T3 cells were more easily detached from the silane surface even though the cells were more spread than on glass. On glass, smaller cells were preferentially detached below 30 dyne/cm2, increasing the mean projected area of the population. Above 30 dyne/cm2, larger cells also detached from the surface. Cell detachment from the silane surfaces did not show any size preference. The strength of adhesion and projected areas on both surfaces increased significantly when the surfaces were preincubated with fibronectin. Simple geometric models of spreading cells were used to estimate the forces exerted on cells. The hydrodynamic forces exerted on spreading cells were similar, but the bond density needed to resist detachment declined as the projected area increased. Analysis of Dil-C18(3) membrane fragments indicated that cell detachment by membrane rupture was a significant mechanism of cell detachment from glass for shear stresses above 40 dyne/cm2, but was unimportant for cell detachment from the silane surfaces. The results indicate that differences in the strength of 3T3 cell adhesion were probably due to differences in bond strength and the numbers of receptor-ligand bonds formed on the two surfaces and, on glass, cell detachment due to membrane failure at higher shear stresses.

3T3 Cells↗

PubMed1992

Heat and autoclave resistance of cell-spreading activity of vitronectin.

We have investigated the heat- and autoclave-resistant properties of the cell-spreading activity of vitronectin, a cell-spreading glycoprotein in animal blood plasma. Vitronectin heated at 100 degrees C for 10 min or autoclaved at 121 degrees C at 1.2 kg/cm2 for 20 min retained the same cell-spreading activity as native vitronectin. In contrast, fibronectin and type-I collagen treated in the same way lost their activity almost completely. GRGDSP remarkably inhibited the cell-spreading activity of native, heated and autoclaved vitronectins. GRGESP did not inhibit the activity of native vitronectin, but, unexpectedly, partially inhibited the activity of both heated and autoclaved vitronectins. In SDS-polyacrylamide gel analysis under reducing conditions, vitronectin heated at 100 degrees C migrated mainly as a monomer, but autoclaved vitronectin migrated at both the top and front of the gel instead of at the position of the monomer. The change in molecular size during the heat- and autoclave treatments was partially prevented by adding 10 mM dithiothreitol or 2% 2-mercaptoethanol to the protein solution.

Amino Acid Sequence↗

PubMed1990

Importation of methicillin-resistant Staphylococcus aureus from Baghdad to Dublin and subsequent nosocomial spread.

We report the spread of a methicillin- and gentamicin-resistant Staphylococcus aureus strain (MGRSA) from the Middle East and its subsequent dissemination within two hospitals in Dublin. The index case, a 30-year-old male with serious blast injuries was transferred from a Baghdad hospital to a Dublin hospital in May 1985. He was heavily infected with two MGRSA strains, one of which spread and was responsible for numerous episodes of nosocomial infection. This strain was very similar to MGRSA isolates recovered in a Baghdad hospital during 1984. This imported strain has now spread to two hospitals in our group causing sepsis. This report emphasizes the difficulty of detecting an imported strain in an endemic area, but above all points to the potential for spread when there is considerable movement of patients and personnel.

Adult↗

PubMed1991

Social disintegration and the spread of AIDS: thresholds for propagation along 'sociogeographic' networks.

Previous work on the asymptotic spread of HIV infection along a low dimensional 'sociogeographic' network--a social network characteristically embedded within a limited geographic area--is extended to explore threshold conditions under which the infection extends widely beyond an initial set of infected individuals or communities. Results for one dimension suggest that threshold behavior is analogous to a chain reaction with criticality determined conjointly by the susceptibility of individuals within a community to a nexus of behavior conducive to rapid HIV spread and by the probability of transmission between susceptible communities. Once threshold is exceeded, a stochastic reformulation finds the asymptotic rate of transmission between communities may be markedly raised by positive correlation between susceptibility to rapid disease spread within a community and the transmissibility between communities, for example outmigration driven by social disintegration or residential instability arising from inherent structural factors associated with community susceptibility, as with male prostitution. Examination of threshold conditions for higher dimensional sociogeographic networks most likely characteristic of disease spread beyond the 'deep ghettos' now suffering the highest burden of infection suggests it is at least as, and likely more, effective to decrease the fraction of population susceptible to the high risk behavioral nexus as it is to lower the probability of disease transmission between susceptible individuals or communities.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗

PubMed1985

Spreading of non-transformed and transformed cells.

Mechanisms of cellular reactions responsible for the spreading of non-transformed cultured tissue cells on the surface of various substrata and relationships of these reactions to the control of cell proliferation are reviewed; the special role of the membrane-cytoskeleton interactions leading to extension and attachment of pseudopods is stressed. Transition of cells from non-transformed to transformed phenotype is characterized by decreased spreading and by decreased dependence of proliferation on spreading. Manifestations of both of these spreading-associated changes are reviewed and their possible mechanisms are discussed. It is suggested that cell transition to transformed phenotype involves shift of an equilibrium between the reactions induced by the two groups of membrane-bound ligands: those attached and those not attached to the substratum.

Animals↗

PubMed1984

The relationship between thermal injury and neutrophil membrane functions as measured by chemotaxis, adherence and spreading.

Thermal injury is frequently associated with acquired immunologic abnormalities including impaired neutrophil (PMN) chemotaxis. To determine if the postburn PMN chemotactic abnormality was associated with abnormalities of other PMN membrane dependent functions, neutrophil adherence, spreading and chemotaxis were measured synchronously and serially in 22 thermally injured patients with mean TBSA burns of 36 per cent. PMN adherence and spreading were greater in the burn patients than in the controls (P less than 0.05; Student's t test). No relationship was noted between neutrophil adherence or spreading with changes in the total neutrophil count. A correlation was found between neutrophil chemotaxis and adherence (chi 2 = 4.13, P less than 0.05) but not between neutrophil chemotaxis and spreading (chi 2 = 2.3, P greater than 0.10). Thus a correlation between neutrophil chemotaxis and adherence was found, suggesting that other neutrophil cell membrane functions, besides chemotaxis, may be affected by thermal injury.

Adolescent↗

PubMed1989

A mechanism of peripheral spread or localization of inflammatory reactions--role of the localized ground substance adaptive phenomenon.

It is known that connective tissue-active peptides (CTAP) are released at sites of inflammation. Some of this material diffuses to immediately adjacent tissue and increases ground substance viscosity and fibroblast proliferation. This contributes to host protection against spread of infections and tumors. In a person with normal inflammatory reactivity, it should prevent spread of mediators and products of local inflammation. However, the host with an increased reactivity in sites of increased ground substance viscosity or who is highly reactive to dilution of tissue fluid would respond with more inflammation. A non-infectious, non-malignant process in a host with a highly reactive inflammatory or immune response could end up with peripheral spread. This could occur in any tissue but it occurs with great vigor in the skin. It could present as a peripheral extension of a local disease process, such as psoriasis, or the migration of cyclic lesions with clearing of the central area. There are over a dozen variants of peripherally spreading, ringed lesions described in the dermatologic literature. This includes erythema marginatum of rheumatic fever, erythema gyratum repens associated with cancer, and erythema annulare centrificum associated with allergic reactions to fungi. Many of the ringed dermatologic lesions have an immunologic component. They tend to be associated with inflammatory immune reactions at distant sites. Dermatologists have been gathering information on the ringed phenomenon at least since Hebra in 1854. The acute localized ground substance adaptive phenomenon is a broadly beneficial biologic response.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed1984

Requirements for cell spreading on polyHEMA coated culture substrates.

We have investigated the topography of polyHEMA coated culture substrates by scanning electron microscopy, and quantitatively assessed their effect upon the spreading activity of mammalian cells. Results indicate a clear correlation between cell spreading activity and polymer film discontinuity. Preparation of polyHEMA films on modified tissue culture substrates has allowed direct investigation of the role of the underlying substrate in regulating cell spreading, and confirms that apparent modulation of cell spreading by polyHEMA reflects increasing expression of the coated surface. We have further employed a spinning technique by which films of precise thickness, down to 0.01 micron, may be produced on coverslips. All polyHEMA coatings prepared in this way are smooth and complete. They do not allow cell attachment at any thickness. We conclude that polyHEMA is non-adhesive for mammalian cells.

Animals↗

PubMed1987

Radical neck dissections for squamous carcinomas: pathological findings and their clinical implications with particular reference to transcapsular spread.

Two hundred fifty radical neck dissections, undertaken for mucosal squamous carcinomas of the head and neck, were reviewed with reference to pathological findings and their clinical implications. No major differences in descriptive surgical pathology were established between irradiated and non-irradiated resections. In general, irradiated dissections had lower total node counts and somewhat fewer nodal metastases involving a smaller number of different nodal groups. The topography of nodal deposits was similar in irradiated and non-irradiated resections. Palpable keratin granulomas (without intact tumor) were almost confined to irradiated patients. Transcapsular spread of tumor from involved lymph nodes was common: it was demonstrated in 160/188 'positive' dissections (85%) and was subclassified as 'macroscopic' in 90 and 'microscopic' in 70. The incidence and extent of transcapsular spread was similar in irradiated and nonirradiated resections. It was more frequently observed in association with large nodal masses but it was also regularly found with small nodal deposits less than 3 cm in diameter. Statistical analyses showed strong associations (p less than 0.0005) between the presence and/or extent of transcapsular spread and subsequent recurrence in the operated neck and overall survival. The predictive value of other clinical and pathological features vis-a-vis local neck recurrence such as numbers of involved nodal groups was weaker. Macroscopic transcapsulr spread emerges as the major prognostic factor for recurrent disease in the neck (p less than 0.0001). Attention is drawn to the advantages of accurate descriptive categories ('macroscopic', 'microscopic') for this critical prognostic feature.

Carcinoma, Squamous Cell↗

PubMed1994

The effect of position on sacral spread of epidural analgesia.

In parturients, extension of epidural analgesia to include the sacral roots is necessary for adequate analgesia during the second stage of labour and for vacuum extraction and forceps delivery. There is clinical evidence that if the sitting position is adopted after local anaesthetic administration, it impairs the sacral spread of analgesia. An in vitro model representing the lumbar spinal canal has been used to demonstrate how, in the vertical position, a CSF plug can prevent downward spread of local anaesthetic. With the model tilted 25 degrees to the horizontal and also in the full horizontal position downward spread occurs. The effect of a 25 degrees head up tilt on sacral spread of epidural analgesia was compared clinically with the horizontal position. Women requesting epidural analgesia during labour were randomly allocated to receive the first epidural dose either with the head end of the bed tilted 25 degrees head up (n = 30) or remaining horizontal (n = 30). All epidurals were sited at L3/4, a test dose of 2 ml of 0.5% bupivacaine was followed by a main dose of 6 ml of 0.5% bupivacaine. Sacral sensory blockade was greater in the head up group. The difference was significant on the left side (P < 0.05) at 15, 20, and 30 minutes after the main dose. There were more patients with blocks extending to S5 (on either the left or right sides) in the head up group at 15, 20 and 30 minutes (P < 0.05 at 20 and 30 minutes on left side).

Journal Article↗

PubMedDate not supplied

A new method for the routine spreading of DNA in protein-free conditions.

Electron microscopic studies of DNA are hampered by difficulties encountered with the spreading of DNA under protein-free conditions. The established and currently popular technique of spreading DNA on carbon membranes treated by glow discharge in an atmosphere of pentylamine is limited with regard to its reproducibility and the proper distribution of spread molecules on the surface of the membranes. A new, reliable, and highly reproducible technique using tri-L-(dimethylaminomethyl)phenol (DMP 30), a promotor factor for spreading circular DNA, linear DNA, and DNA-protein complexes, is described in this paper. Monolayers of DMP 30 are formed at the air-water interface by a microdiffusion procedure on droplets. DNA molecules that diffuse on this monolayer can easily be picked up on hydrophobic carbon membranes. This method, which is easy, reproducible, and fast, will facilitate electron microscopic studies of DNA-protein interactions.

DNA↗

PubMed1995

Blockade of CD28/B7-1 interaction prevents epitope spreading and clinical relapses of murine EAE.

Relapsing experimental autoimmune encephalomyelitis (R-EAE) induced with the immunodominant epitope from proteolipid protein, PLP139-151, is characterized by the development of recurrent relapses with recruitment of T cells reactive to additional myelin peptides, including PLP178-191 (epitope spreading). In this study, we have determined that the CD28/B7 costimulatory pathway is involved in this process. We found preferential up-regulation of B7-1 during the course of R-EAE and a selective increase in its functional costimulatory activity, relative to B7-2. Anti B7-1 F(ab) fragment therapy, but not anti B7-2 MAb therapy, blocked clinical relapses, ameliorated CNS pathology, and blocked epitope spreading. These results suggest that the maintenance of autoimmune reactivity in EAE depends on CD28/B7-1-dependent costimulation of newly recruited T cells responsible for epitope spreading. These studies have important implications for the role of epitope spreading in disease progression and the clinical application of costimulatory antagonists in autoimmune diseases.

Animals↗

PubMed2006

A role for WASP Interacting Protein, WIP, in fibroblast adhesion, spreading and migration.

The WASP (Wiskott Aldrich Syndrome Protein) Interacting Protein, WIP, regulates actin polymerization and the formation of actin-rich structures such as filopodia and lamellipodia, each of which is involved in cellular adhesion, spreading and migration. To define the role for WIP in these activities, we analysed cell adhesion and spreading as well as the redistribution of polymerised actin and paxillin that occurred when fibroblasts were plated onto different substrata. We compared the effect of WIP overexpression (gain of function) with that of WIP deficiency (loss of function) on these parameters. WIP-overexpression delayed cellular adhesion and spreading, an effect that could be compensated for by exposure to Y-27632, a well characterized ROCK (Rho kinase) inhibitor. WIP overexpression augmented the phosphorylation of Erk and JNK induced by binding to fibronectin, suggesting that WIP participates in signal transduction pathways initiated by integrin engagement. Conversely, WIP deficiency accelerated fibroblast adhesion to plastic and led to the formation of enlarged focal adhesions. The influence of WIP on fibroblast migration was measured by scratch assay. WIP-overexpression reduced migration while WIP-deficiency increased it, suggesting that WIP acts as a negative regulator of fibroblast migration. Together, these findings suggest a novel role for WIP in fibroblast adhesion, spreading and migration.

Amides↗

PubMed2005

Regulation of mesenchymal stem cell attachment and spreading on hydroxyapatite by RGD peptides and adsorbed serum proteins.

The successful development of biomaterials must take into consideration how those surfaces will interact with in vivo processes such as adsorption of endogenous proteins. In this study, we examined whether modifying highly adsorbent materials like hydroxyapatite (HA) with RGD peptides would improve mesenchymal stem cell (MSC) adhesion. We found that RGD, alone, was not sufficient to promote full cell spreading. However, given that RGD-modified HA will likely adsorb osteogenic serum proteins in vivo, we evaluated MSC behavior on HA pre-coated with RGD, then over-coated with serum (RGD/FBS). Interestingly, RGD/FBS coatings additively stimulated MSC attachment and spreading compared to either coating alone, but only at low RGD coating concentrations. High RGD concentrations inhibited cell attachment, and completely eliminated cell spreading on RGD/FBS surfaces. To better understand the mechanism by which RGD and adsorbed serum proteins interactively regulate cell behavior, we monitored the deposition of fibronectin (FN) from serum onto HA pre-coated with increasing RGD concentrations. These studies showed that high RGD concentrations did not inhibit FN adsorption, therefore cell spreading is attenuated by mechanisms other than lack of FN availability. Collectively, our results suggest a potential therapeutic benefit for functionalizing HA with RGD, however such a benefit will likely depend upon the RGD density.

Adolescent↗

PubMed2006

Meta-analysis of the prognostic significance of perinodal spread in head and neck squamous cell carcinomas (HNSCC) patients.

To assess the risk factor of capsular rupture for individual prognosis and potential therapeutic decision making, the present meta-analysis elaborated the prognostic significance of perinodal spread in a large group of patients suffering from head and neck squamous cell carcinomas (HNSCC). A review of the published literature was conducted, and fixed and random effects models were applied for estimation of the summarised odds ratio and 95% confidence intervals, including a test for homogeneity of the odds ratios. Study methodology allowed the enrollment of only nine studies of 115 published papers. Excluded studies lacked regarding primary tumour location, number and location of lymph node metastases, values on five-year survival, or adequate follow-up data. A summarised odds ratio of 2.7 leads to the conclusion that perinodal spread negatively impacts the five-year survival. The lower confidence limit of more than 2 also supports the concept that perinodal spread significantly reduces (doubled risk) the five-year-survival. These results support the conclusion that perinodal spread is a significant adverse risk factor for survival in patients with HNSCC.

Carcinoma, Squamous Cell↗