Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Attachment”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 217 records · Page 12Linked to original sources

Attachment of human epithelial cells and periodontal ligament fibroblasts to tooth dentin.

A goal of treatment in periodontal therapy is to regenerate a new fibroblastic attachment rather than to repair lost attachment with a long junctional epithelium. To date, there is no evidence that fibroblastic attachment formed during regeneration is stronger or less susceptible to periodontal breakdown than a long junctional epithelial attachment. We measured the rate and strength of attachment of epithelial cells (NHEK) and periodontal ligament fibroblasts (PDLF) cultured individually and cocultured to dentin surfaces to determine which cell type has a faster attachment rate and greater adhesive strength to human dentin, and whether the cell types attach independently. Longitudinal dentin slices were seeded with either PDLF or NHEK for 2 or 24 h. The specimens were placed into a parallel plate flow chamber and defined laminar shear stresses were applied. Shear stress was created by step increases in fluid flow rate. Effluent fluid was collected and cell numbers (detached) were counted using a hemocytometer. Cocultures of PDLF and NHEK at three seeding ratios (10:1, 1:1, 1:10) were also tested. Each cell type attached equally well to polystyrene or dentin. PDLF showed a stronger attachment to polystyrene and dentin at 24 versus 2 h. NHEK attached to polystyrene or dentin equally well at 2 and 24 h. NHEK were more strongly attached after 2 h when compared to PDLF. PDLF were more strongly attached after 24 h versus NHEK. When NHEK and PDLF were seeded together on dentin at a 1:1 ratio, PDLF appeared to be more strongly attached than NHEK at 2 but not 24 h. At a ratio of 10 PDLF:1 NHEK, PDLF appeared to be more strongly attached at 2 and 24 h. At a ratio of 1 PDLF:10 NHEK, NHEK appeared to be more strongly attached at 2 h, but PDLF showed a trend of stronger attachment at 24 h. We conclude that epithelial cells attach more quickly to dentin surfaces than PDLF, but do not demonstrate increased attachment strength over time (PDLF do show increased attachment strength overtime). The purported advantages of periodontal regeneration over periodontal repair are supported by our results. Furthermore, our results support the concept of guided tissue regeneration. On the basis of on cellular competition experiments, epithelial cells and PDLF do not act independently, because epithelial cells enhanced the attachment rate of PDLF.

Cell Adhesion↗

Models of the mechanism for crossbridge attachment in smooth muscle.

The mechanism responsible for formation of attached, dephosphorylated crossbridges (latchbridges) in smooth muscle is controversial. Myosin light chain phosphorylation may be obligatory for crossbridge attachment; if this were the case, latchbridges would arise solely by dephosphorylation of attached, phosphorylated crossbridges. Alternatively, the presence of attached crossbridges could induce cooperative activation by allowing dephosphorylated crossbridges to attach to the thin filament. We evaluated whether four-state models based on dephosphorylation and/or cooperativity-regulated attachment could quantitatively predict smooth muscle contractile behaviour. Five quantitative models for transitions between crossbridge states were developed. Mechanisms for latchbridge formation included: (1) dephosphorylation, (2) cooperativity-regulated attachment dependent only on attached, phosphorylated crossbridges, (3) cooperativity-regulated attachment dependent on all attached crossbridges, (4) dephosphorylation and cooperativity-regulated attachment dependent only on attached, phosphorylated crossbridges, and (5) dephosphorylation and cooperativity-regulated attachment dependent on all attached crossbridges. All five models approximated the time course of contraction and the dependence of steady-state stress on myosin phosphorylation in the swine carotid artery. In the two models that had cooperative attachment regulated by all attached crossbridges, small increases in the rate constant for cooperativity-regulated attachment resulted in positive feedback and irreversible contraction. We suggest that a number of four-state crossbridge models can predict contractile behaviour in arterial smooth muscle. Potentially, latchbridges could be formed by both dephosphorylation and cooperativity-regulated attachment. If cooperativity-regulated latchbridge attachment does exist in smooth muscle, we suggest that it should be dependent only on the number of phosphorylated crossbridges rather than all attached crossbridges.

Actomyosin↗

Role of curli fimbriae in mediating the cells of enterohaemorrhagic Escherichia coli to attach to abiotic surfaces.

AIMS: The objectives of this study were to evaluate the role of curli in assisting the cells of enterohaemorrhagic Escherichia coli (EHEC) in attaching to abiotic surfaces and to determine the influence of cell-surface contact time on the efficiency of the attachment. METHODS AND RESULTS: Three pairs of EHEC cultures, each with a curli-expressing and a noncurli-expressing variant (O111:H- 7-57C+ and O157:H7 5-9C-, O157:H7 5-11C+ and 5-11C-, as well as O103:H2 7-52C+ and 7-52C-), were allowed to interact with polystyrene, glass, stainless steel and rubber surfaces at 28 degrees C for 24 h (short-term attachment) or 7 days (long-term attachment). The quantities of the cells that attached to the surfaces were measured daily in the long-term attachment study, and in 4 h intervals in the short-term attachment study. Quantification of the cells that attached to the surfaces was accomplished with a crystal violet binding assay. The results of the long-term attachment study indicated that 7-57C+ attached to the polystyrene and glass surfaces more efficiently (P < 0.05) than did 5-9C-. The curli-expressing variant of 5-11 possessed a better ability to adhere to the polystyrene and glass surfaces than did its noncurli-expressing counterpart (P < 0.05). The differences in attachment between 7-52C+ and 7-52C- on polystyrene and stainless steel surfaces were statistically significant (P < 0.05). However, the attachment of the pair on the glass surfaces was statistically insignificant (P > 0.05). In addition, the two members of all three EHEC pairs attached equally well to rubber surfaces (P > 0.05). In the short-term attachment study, only the pair of 7-52 attached differently on glass and stainless steel surfaces (P < 0.05). CONCLUSIONS: These results suggest that curli could be an important cell surface component to mediate the attachment of some EHEC cells to certain abiotic surfaces. Cell-surface contact time could have a significant influence on EHEC attachment to abiotic surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: The study signifies a possible role of curli in assisting the cells of EHEC in attaching to food-contact surfaces. It underlines the importance of cleaning and sanitizing food-contact surfaces regularly and thoroughly, and of identifying chemical agents that can effectively remove the attached EHEC cells from these surfaces.

Bacterial Adhesion↗

Comparison of healing of allograft/endoprosthetic composites with three types of gluteus medius attachment.

This study compared three methods of gluteus medius tendon attachment to an allograft/endoprosthetic composite of the proximal 25% of the femur in a canine model. The three methods were bone to bone, tendon to bone, and tendon to tendon attachment. In an in vivo study, 24 dogs were assigned to three groups of eight dogs each, and serial radiography and weight-bearing analyses were performed throughout the study. The dogs were killed at 6 months, and the specimens were tested in tension to failure and were analyzed histologically. In an in vitro study, each repair was done on six limbs, with a contralateral limb serving as a control for each. In these specimens, the bone to bone attachments were significantly stronger (99.1% of the controls) than the tendon to bone attachments (71.8% of the controls) and the tendon to tendon attachments (40.0% of the controls); there were no differences in tensile stiffness among the three types of attachment. By 6 months, the tensile strength of the tendon to tendon attachments increased significantly and that of the tendon to bone attachments decreased significantly. There were no significant differences in tensile strength among the three types of attachment. The tensile stiffness of the bone to bone attachments (91.0% of the controls) was significantly greater than that of the tendon to bone attachments (40.8% of the controls) but not significantly different from that of the tendon to tendon attachments (63.2% of the controls). The bone to bone attachment was associated with increased bone resorption, bone remodeling, and bone porosity, accompanied by thinner allograft cortices, when compared with the other types of attachment. In dogs with a bone to bone attachment, weight-bearing increased more slowly than in dogs with either of the other two attachments. These changes associated with the bone to bone attachment may merely be secondary to healing of the bone to bone attachment to the greater trochanter; therefore, they may only be temporary phenomena or they may be the portents for long-term complications. Longer term studies of at least 1-2 years must be performed before these questions can be answered.

Animals↗

Clinical course of chronic periodontitis. III. Patterns, variations and risks of attachment loss.

AIM: The purpose of this study was to assess the rate of attachment loss during various stages of adult life in a well-maintained middle-class population. MATERIAL AND METHODS: The data originated from a 26-year longitudinal study of Norwegian males who had received regular and adequate dental care and practised daily oral home care. The initial examination in 1969 included 565 individuals aged between 16 and 34 years. Subsequent examinations took place in 1971, 1973, 1975, 1981, 1988 and 1995. Thus, the study covers the age range of 16-59 years. The rate of the annual attachment loss was calculated as the difference between the individual mean attachment loss between two examinations divided by the years between examinations. The mean annualized relative risk of attachment loss was calculated as the frequency distribution of sites with initial periodontal attachment loss (loss of attachment at the first time of occurrence > or = 2 mm) and healthy sites (loss of attachment always < 2 mm). For comparison of significant changes in annual attachment loss rates between the age groups and mean annualized relative risks of attachment loss as they proceeded through adult life, the Wilcoxon Mann-Whitney U-test was used. RESULTS: The mean overall individual attachment loss during 44 years (between 16 and 59 years) totaled 2.44 mm (range 0.14-2.44 mm), averaging an annual mean rate of 0.05 mm/year. The highest annual rate of attachment loss occurred before 35 years of age (0.08-0.1 mm/year), after which the mean annual rate decreased to about 0.04-0.06 mm/year for the next three decades of life leading to 60 years. The mean annualized relative risk of initial attachment loss increased significantly from adolescence (1.2%) to the maximum at 30-34 years of age (6.9%). After the age of 34 years, the risk of initial attachment loss decreased again, but after the age of 40 years, another continuous increase was observed. CONCLUSIONS: Over a 26-year period, 25% of the subjects went through adult life with healthy and stable periodontal conditions. The remaining 75% developed slight to moderately progressing periodontal disease with progression rates varying between 0.02 and 0.1 mm/year with a cumulative mean of loss of attachment of 2.44 mm as they approached 60 years of age. The annual mean rate and the mean annualized risk of initial attachment loss were highest between 16 and 34 years of age. Only 20% of the sites continued to lose further attachment during the remainder of the observation period, and less than 1% of the sites showed substantial loss of attachment (> 4 mm).

Adolescent↗

Maternal secure-base scripts and children's attachment security in an adopted sample.

Studies of families with adopted children are of special interest to attachment theorists because they afford opportunities to probe assumptions of attachment theory with regard to the developmental timing of interactions necessary to form primary attachments and also with regard to effects of shared genes on child attachment quality. In Bowlby's model, attachment-relevant behaviors and interactions are observable from the moment of birth, but for adoptive families, these interactions cannot begin until the child enters the family, sometimes several months or even years post-partum. Furthermore, because adoptive parents and adopted children do not usually share genes by common descent, any correspondence between attachment representations of the parent and secure base behavior of the child must arise as a consequence of dyadic interaction histories. The objectives of this study were to evaluate whether the child's age at the time of adoption or at the time of attachment assessment predicted child attachment security in adoptive families and also whether the adoptive mother's internal attachment representation predicted the child's attachment security. The participants were 106 mother - child dyads selected from the 406 adoptions carried out through the Lisbon Department of Adoption Services over a period of 3 years. The Attachment Behavior Q-Set (AQS; Waters, 1995) was used to assess secure base behavior and an attachment script representation task was used to assess the maternal attachment representations. Neither child's age at the time of adoption, nor age of the child at assessment significantly predicted the AQS security score; however, scores reflecting the presence and quality of maternal secure base scripts did predict AQS security. These findings support the notion that the transmission of attachment security across generations involves mutual exchanges and learning by the child and that the exchanges leading to secure attachment need not begin at birth. These results complement the findings and conceptual arguments offered by Bowlby and Ainsworth concerning the critical influence of maternal representations of attachment to the quality of attachment security in children.

Adoption↗

Sulfhydryl-dependent attachment of Treponema denticola to laminin and other proteins.

Attachment of Treponema denticola ATCC 35405 to laminin, a major basement membrane protein, and to other proteins was studied. Microdilution plates were coated with the proteins, and the attachment of T. denticola was measured by the enzyme-linked immunosorbent assay technique. Compared with bovine serum albumin (BSA), T. denticola had a high affinity to laminin, fibronectin, fibrinogen, and gelatin, as well as to type I and type IV collagens. Attachment to RGD peptide (Gly-Arg-Gly-Asp-Ser, the integrin recognition sequence) was only about 30% of that to laminin and was comparable to attachment to BSA. Tests with laminin fragments obtained through elastase digestion showed that the spirochetes attached well to an A-chain 140-kDa fragment involved in eukaryote cell attachment but did not attach to a 50-kDa fragment that includes the heparin binding site. Pretreatment of T. denticola with soluble laminin, fibronectin, gelatin, BSA, or fibrinogen had no effect on the attachment of the bacteria to laminin or fibronectin. A wide variety of compounds were tested for their possible inhibitory actions on the attachment. While most treatments of T. denticola ATCC 35405 had little or no effect on the attachment to proteins, sulfhydryl reagents p-chloromercuribenzoic acid (pCMBA) and oxidized glutathione inhibited the attachment by 70 to 99%, depending on the protein. When T. denticola was first allowed to attach to proteins, addition of pCMBA or oxidized glutathione could no longer reverse the attachment. Heat treatment of the spirochetes also markedly reduced the attachment to laminin, gelatin, and fibrinogen but not to BSA. Mixed glycosidase treatment of the spirochetes inhibited the attachment by 20 to 80%. None of the above treatments of the substrate proteins had any marked effect on the spirochete attachment. The results indicate that T. denticola has the capacity to bind to many different kinds of proteins by utilizing specific attachment mechanisms. The binding appears to involve protein SH groups and/or carbohydrate residues on the surface of T. denticola.

Amino Acid Sequence↗

In vitro attachment of phylloplane yeasts to Botrytis cinerea, Rhizoctonia solani, and Sclerotinia homoeocarpa.

The ability of yeasts to attach to hyphae or conidia of phytopathogenic fungi has been speculated to contribute to biocontrol activity on plant surfaces. Attachment of phylloplane yeasts to Botrytis cinerea, Rhizoctonia solani, and Sclerotinia homoeocarpa was determined using in vitro attachment assays. Yeasts were incubated for 2 d on potato dextrose agar (PDA) prior to experimentation. A total of 292 yeasts cultured on PDA were screened for their ability to attach to conidia of B. cinerea; 260 isolates (89.1%) attached to conidia forming large aggregates of cells, and 22 isolates (7.5%) weakly attached to conidia with 1 or 2 yeast cells attached to a few conidia. Ten yeasts (3.4%), including 8 isolates of Cryptococcus laurentii, 1 isolate of Cryptococcus flavescens, and an unidentified species of Cryptococcus, failed to attach to conidia. All non-attaching yeasts produced copious extracellular polysaccharide (EPS) on PDA. Seventeen yeast isolates did not attach to hyphal fragments of B. cinerea, R. solani, and S. homoeocarpa after a 1 h incubation, but attachment was observed after 24 h. Culture medium, but not culture age, significantly affected the attachment of yeast cells to conidia of B. cinerea. The 10 yeast isolates that did not attach to conidia when grown on agar did attach to conidia (20%-57% of conidia with attached yeast cells) when cultured in liquid medium. Attachment of the biocontrol yeast Rhodotorula glutinis PM4 to conidia of B. cinerea was significantly greater at 1 x 10(7) yeast cells x mL(-1) than at lower concentrations of yeast cells. The ability of yeast cells to attach to fungal conidia or hyphae appears to be a common phenotype among phylloplane yeasts.

Ascomycota↗

Temperament and attachment: one construct or two?

In this chapter we described the constructs of temperament and attachment and have discussed similarities and differences between the two. We addressed the issue of whether temperament contributes to overall attachment security or to the specific type of attachment that children display. We conclude that although temperament may influence the type of secure and insecure attachment relationship children form with their parent, temperament alone will not determine if a child is classified as securely or insecurely attached. We presented evidence suggesting that certain dimensions of temperament, specifically negative emotionality, may be associated with infants' behavior during the Strange Situation, such as proneness-to-distress during separations. However, we noted that these temperament dimensions do not predict overall security of attachment. It is likely that although no single temperament characteristic, such as proneness-to-distress, in and of itself determines overall attachment security, it is possible that a constellation of temperament characteristics may be more strongly related to attachment security. The examination of constellations of temperament characteristics may be particularly useful for furthering our understanding of individual differences within attachment classifications. Such an approach may elucidate the reasons why infants are classified into one subgroup of secure, insecure-avoidant, or insecure-resistant attachment versus another subgroup. Furthermore, we suggest that the collection of findings regarding temperament and attachment not only underscores the importance of a transactional approach to early social-emotional development, but emphasizes that temperament and attachment can make unique and interactive contributions to children's social-emotional functioning. That is, the goodness-of-fit between infant and parent characteristics may best predict security of attachment. Although child characteristics clearly contribute to the development of the parent-child relationship, we believe that the effects of infant temperament on infant-caregiver attachment may well be indirect, and may be moderated by such variables as maternal personality and social support. Thus, taken together, a growing literature clearly indicates that although temperament and attachment security are interrelated, they are by no means interchangeable constructs. To return to our guiding question, "Temperament and attachment: One construct or two?" We reply, "two."

Child↗

The mechanism of virus attachment to host cells. I. The role of ions in the primary reaction.

T1 virus does not attach to its host cell, E. coli B, in distilled water. By the proper addition of salts the rate of attachment can be adjusted to any desired value up to the maximum limit set by the diffusion rate of the virus. Salts of Ca(++), Mg(++), Ba(++), and Mn(++) bring about a reaction rate representing 100 per cent collision efficiency in a concentration of 5 x 10(-4)M. Both greater and smaller concentrations depress the attachment velocity. Salts of Na(+), K(+), NH(4) (+), and Li(+) display a similar pattern but require a tenfold greater concentration than that of the previous group to produce the same effect. Moreover, the maximum velocity attainable in solutions containing only monovalent cations is only half that achieved by the divalent salts. The trivalent cations Al(3+), Cr(3+), Fe(3+) permanently inactivate the virus. Activation by Mg(++) of an inert mixture of virus and host cells in distilled water is so rapid as to be beyond the limit of the resolving time of the experimental procedure, which is 20 seconds. The temperature dependence curve of virus-cell adsorption exhibits a maximum at 37 degrees C. and falls to a value representing approximately 3 per cent collision efficiency at 1 degrees C. Identical curves are obtained in nutrient broth and in 10(-)M MgCl(2) solution. Bacteriophage can be quantitatively adsorbed on to glass filters. In a study of several viruses this attachment reaction was found to require the same cofactors-both organic, like ltryptophane, as well as inorganic-which each specific virus required for its attachment to its host cell. The suggestion is made that the attachment of viruses to these filters is a useful model for their attachment to host cells. Virus attachment to glass filters is reversible. Such adsorbed virus can be recovered almost quantitatively by washing the filter with a solution in which the attachment reaction does not occur. Virus attachment to host cells is similarly reversible at least in its primary step. Distilled water at 0 degrees C. can produce almost complete liberation of T2 virus from host cells infected in 0.02 M NaCl solution. Two significant differences between the behavior of glass filters and host cells toward T1 virus are: (a) an excess ion concentration fails to inhibit virus attachment to the glass as it does to the host cell; and (b) no decrease in efficiency of attachment to glass occurs at low temperatures. These facts suggest that the inhibiting action on the infective process of excess cations and low temperatures involves chemical groupings on the cell surface, rather than on the virus. There is no detectable attachment whatever of T1 virus to E. coli cells specifically resistant to it, though still susceptible to other viruses. This experiment indicates that the ion-controlled attachment forces here considered are involved in the host-virus specificity. This conclusion is strengthened by the fact that several different viruses with different host-cell specificities have different ionic requirements for cell attachment. All of these observations lend themselves to explanation by a mechanism which pictures an initial addition reaction of cations to specific sites on the surface of the virus in particular, and possibly also of the host cell. Two complementary electrostatic configurations are so produced which can unite in a reaction with a high biological specificity, which yet exhibits 100 per cent collision efficiency. An excess of ions may cover up some of the attachment sites and so inhibit the reaction. By this picture the specificity of virus-cell invasion depends upon the binding energies of sites on both bodies for various ions, and the distribution of these sites over the two surfaces. Possible relationships of such a process to other biological systems are discussed.

Escherichia coli↗

Measuring attachment representation in an FMRI environment: a pilot study.

This exploratory study is the first to examine the neural correlates of attachment status in adults. The study examined the feasibility of assessing attachment narratives in the functional magnetic resonance imaging (fMRI) environment by challenging subjects to tell attachment stories to specific attachment pictures from the Adult Attachment Projective (AAP) while being scanned. We investigated theoretically derived hypotheses regarding predicted differences in the brain activation patterns of individuals whose attachment status was organized (resolved) versus disorganized (unresolved) with respect to attachment trauma (e.g., as associated with loss through death, abuse, threat of abandonment). Adult attachment was assessed using the AAP, a new representational attachment measure that we thought might be suitable for use in the fMRI environment. This measure was used to obtain a preliminary picture of the neural processes associated with the activation of attachment in 11 healthy female adults. Results are reported from a second-level analysis (p < 0.001 uncorrected) and confirm that the AAP is a feasible measure for use in a neuroimaging environment. Cerebral activation during continuous speech yielded results consistent with the literature. Brain activation was demonstrated in expected visual and semantic brain regions. Furthermore, we found that the rate of articulation was positively correlated with activation in the right superior temporal gyrus. The results of theoretically derived attachment hypotheses showed no differences at the chosen level of significance when comparing the 'all attachment pictures' effect between both groups (resolved vs. unresolved). More interestingly, we found a significant interaction effect between the sequence of pictures and attachment category. Only the unresolved participants showed increasing activation of medial temporal regions, including the amygdala and the hippocampus, in the course of the AAP task. This pattern was demonstrated especially at the end of the AAP task where the pictures are drawn to portray traumatic situations. We interpret these results as confirming our hypothesis, linking unresolved attachment to emotional dysregulation of the attachment system. These results are discussed in relation to assessing attachment in an fMRI environment and future research in this area.

Adult↗

Magnesium-dependent attachment and neurite outgrowth by PC12 cells on collagen and laminin substrata.

We report a study of the substratum and medium requirements for attachment and neurite outgrowth by cells of the pheochromocytoma-derived PC12 line. In attachment medium containing both Ca2+ and Mg2+, more than 50% of cells attached within 1 hr to petri dishes coated with native collagen Types I/III or II, native or denatured collagen Type IV, laminin, wheat germ agglutinin (WGA), or poly-L-lysine; attachment to dishes coated with nerve growth factor (NGF) was only about 20% and attachment to uncoated dishes or to dishes coated with fibronectin or gelatin was almost nil. Neither prior culturing in the presence of NGF nor addition of NGF to the attachment medium significantly affected the extent of attachment to collagen or laminin. With Ca2+ (1 mM) as the sole divalent cation, cells attached normally to WGA, polylysine, and NGF, but failed to attach to collagen or laminin. With Mg2+ (1 mM) as the only divalent cation, attachment to all substrata was about the same as in medium with both Ca2+ and Mg2+. Like the ionic requirements, the kinetics of attachment, insensitivity to protease treatment of the cells, and inhibition by low temperature and sodium azide were similar for PC12 attachment to collagen and laminin, suggesting that a common molecular mechanism may underlie attachment to these substrata. The only significant difference observed was that addition of WGA (30 micrograms/ml) to the attachment medium inhibited attachment to collagen but promoted attachment to laminin. Finally, PC12 cells extended neurites on laminin, on native collagens I/III, II, and IV, and on denatured collagen IV; they did not extend neurites on denatured collagens I/III or II, NGF, or WGA. Neurite outgrowth on collagen and laminin occurred with Mg2+ as the sole divalent cation. These results suggest that the same Mg2+-dependent adhesion mechanism operates at the cell body and at the growth cone.

Adrenal Gland Neoplasms↗