Search

Alpha-1,3-glucan is important for pathogenesis by Aspergillus fumigatus, but the mechanism is unclear since the deletion has no hyphal phenotype. We dissected the roles of A. nidulans α-1,3-glucan in constitutive overexpression strains. Constitutive high-level α-1,3-glucan synthase activity increased hyphal wall thickness, but colonies grew slowly and sporulated poorly and had much higher adhesion to hydrophobic materials. Surprisingly, this overexpression strain formed a biofilm-like structure in plastic culture wells that was as adhesive as wild-type A. fumigatus. These results suggest α-1,3-glucan has important roles in fungal cellular adhesion and may contribute to fungal pathogenesis. [ABSTRACT FROM AUTHOR]

Abstract: Playing an instrumental role in the life of plants, pollen microparticles are one of the most fascinating biological materials in existence, with abundant and renewable supply, ultrahigh durability, and unique, species‐specific architectural features. Aside from their biological role, pollen microparticles also demonstrate broad utility as functional materials for drug delivery and microencapsulation, and increasingly for emulsion‐type applications. As natural pollen microparticles are predominantly hydrophobic, developing robust surface functionalization strategies to increase surface hydrophilicity would increase the range of colloidal science applications, including opening the door to interfacing microparticles with biological cells. This research investigates the extraction and light‐induced surface modification of discrete pollen microparticles from bee‐collected pollen granules toward achieving functional control over the responses elicited from discrete particles in colloidal science and cellular applications. Ultraviolet–ozone treatment is shown to increase the proportion of surface elemental oxygen and ketones, leading to increased surface hydrophilicity, enhanced particle dispersibility, tunable control over Pickering emulsion characteristics, and enhanced cellular adhesion. In summary, the findings demonstrate that light‐induced surface modification improves the functional properties of pollen microparticles, and such insights also have broad implications across materials science and environmental science applications. [ABSTRACT FROM AUTHOR]

We derive a Cahn-Hilliard-Darcy model to describe multiphase tumour growth taking interactions with multiple chemical species into account as well as the simultaneous occurrence of proliferating, quiescent and necrotic regions. A multitude of phenomena such as nutrient diffusion and consumption, angiogenesis, hypoxia, blood vessel growth, and inhibition by toxic agents, which are released for example by the necrotic cells, are included. A new feature of the modelling approach is that a volume-averaged velocity is used, which dramatically simplifies the resulting equations. With the help of formally matched asymptotic analysis we develop new sharp interface models. Finite element numerical computations are performed and in particular the effects of necrosis on tumour growth are investigated numerically. In particular, for certain modelling choices, we obtain some form of focal and patchy necrotic growth that have been observed in experiments. [ABSTRACT FROM AUTHOR]

Retinoschisin (RS1) is a secreted protein that is essential for maintaining integrity of the retina. Numerous mutations in RS1 cause X-linked retinoschisis (XLRS), a progressive degeneration of the retina that leads to vision loss in young males. A key manifestation of XLRS is the formation of cavities (cysts) in the retina and separation of the layers (schisis), disrupting synaptic transmission. There are currently no approved treatments for patients with XLRS. Strategies using adeno-associated viral (AAV) vectors to deliver functional copies of RS1 as a form of gene augmentation therapy, are under clinical evaluation. To improve therapeutic strategies for treating XLRS, it is critical to better understand the secretion of RS1 and its molecular function. Immunofluorescence and immunoelectron microscopy show that RS1 is located on the surfaces of the photoreceptor inner segments and bipolar cells. Sequence homology indicates a discoidin domain fold, similar to many other proteins with demonstrated adhesion functions. Recent structural studies revealed the tertiary structure of RS1 as two back-to-back octameric rings, each cross-linked by disulfides. The observation of higher order structures in vitro suggests the formation of an adhesive matrix spanning the distance between cells (∼100 nm). Several studies indicated that RS1 readily binds to other proteins such as the sodium-potassium ATPase (NaK-ATPase) and extracellular matrix proteins. Alternatively, RS1 may influence fluid regulation via interaction with membrane proteins such as the NaK-ATPase, largely inferred from the use of carbonic anhydrase inhibitors to shrink the typical intra-retinal cysts in XLRS. We discuss these models in light of RS1 structure and address the difficulty in understanding the function of RS1. [ABSTRACT FROM AUTHOR]

Two main problems limit the success of titanium implants: bacterial infection, which restricts their osseointegration capacity; and the stiffness mismatch between the implant and the host cortical bone, which promotes bone resorption and risk of fracture. Porosity incorporation may reduce this difference in stiffness but compromise biomechanical behavior. In this work, the relationship between the microstructure (content, size, and shape of pores) and the antibacterial and cellular behavior of samples fabricated by the space-holder technique (50 vol % NH4HCO3 and three ranges of particle sizes) is established. Results are discussed in terms of the best biomechanical properties and biofunctional activity balance (cell biocompatibility and antibacterial behavior). All substrates achieved suitable cell biocompatibility of premioblast and osteoblast in adhesion and proliferation processes. It is worth to highlighting that samples fabricated with the 100−200 μm space-holder present better mechanical behavior—in terms of stiffness, microhardness, and yield strength—which make them a very suitable material to replace cortical bone tissues. Those results exposed the relationship between the surface properties and the race of bacteria and mammalian cells for the surface with the aim to promote cellular growth over bacteria.

Regenerative medicine is taking great advantage from the use of biomaterials in the treatments of a wide range of diseases and injuries. Among other biomaterials, self-assembling peptides are appealing systems due to their ability to spontaneously form nanostructured hydrogels that can be directly injected into lesions. Indeed, self-assembling peptide scaffolds are expected to behave as biomimetic matrices able to surround cells, to promote specific interactions, and to control and modify cell behavior by mimicking the native environment as well. We selected three pentadecapeptides inspired by Human Tropoelastin, a natural protein of the extracellular matrix, expected to show high biocompatibility. Moreover, the here proposed self-assembling peptides (SAPs) are able to spontaneously aggregate in nanofibers in biological environment, as revealed by AFM (Atomic Force Microscopy). Peptides were characterized by XPS (X-ray Photoelectron Spectroscopy) and IRRAS (Infrared Reflection Absorption Spectroscopy) both as lyophilized (not aggregated) and as aggregated (nanofibers) samples in order to investigate some potential differences in their chemical composition and intermolecular interactions, and to analyze the surface and interface of nanofibers. Finally, an accurate investigation of the biological properties of the SAPs and of their interaction with cells was performed by culturing for the first time human Mesenchymal Stem Cells (hMSCs) in presence of SAPs. The final aim of this work was to assess if Human Tropoelastin-inspired nanostructured fibers could exert a cytotoxic effect and to evaluate their biocompatibility, cellular adhesion and proliferation. [ABSTRACT FROM AUTHOR]

Signal-induced proliferation-associated protein 1 (SIPA1) is known to be a GTPase activating protein. Overexpressed SIPA1 is related to metastatic progression in breast and prostate cancers; however, the relevance of SIPA1 in oral squamous cell carcinoma (OSCC) is still unknown. The aim of this study was to examine SIPA1 expression and its functional mechanisms in OSCC. SIPA1 mRNA and protein expressions were analyzed by quantitative reverse transcriptase-polymerase chain reaction, Western blot analysis, and immunohistochemistry. The expressions of SIPA1 were up-regulated significantly in vitro and in vivo . Moreover, SIPA1 expression was correlated with regional lymph node metastasis. We next assessed the cellular functions associated with tumoral metastasis using SIPA1 knockdown (shSIPA1) cells and analyzed the downstream molecules of SIPA1, i.e., bromodomain containing protein 4(BRD4), integrin beta1 (ITGB1), and matrix metalloproteinase 7 (MMP7). The shSIPA1 cells showed decreased invasiveness and migratory activities, however cellular adhesion ability was maintained at a high level. In addition, ITGB1 expression was greater in shSIPA1 cells, whereas MMP7 expression was lower than in control cells. This research is the first to establish that SIPA1 promotes cancer metastasis by regulating the ITGB1 and MMP7. Therefore, SIPA1 might be a novel therapeutic target for patients with lymph node metastasis of OSCC. [ABSTRACT FROM AUTHOR]

Background: Affective temperaments are intermediate phenotypes for major affective disorders and are reported to have a neuroimmune etiopathogenesis. Here we investigated the role of soluble intercellular cell adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) in affective temperaments and mood symptoms in healthy adults.Methods: Healthy adults (n=94) were screened for psychiatric disorders using the nonpatient version of the Structured Clinical Interview for DSM-IV-I and II. Subjects with medical conditions associated with changes in inflammatory response were excluded, deriving the final sample (n=68). Affective temperaments were evaluated with Temperament Evaluation of Memphis, Pisa, Paris and San Diego-Autoquestionnaire (TEMPS-A). State mood symptoms were assessed using the Young Mania Rating Scale and Montgomery-Åsberg Depression Rating Scale. Serum sICAM-1 and sVCAM-1 levels were measured using enzyme-linked immunosorbent assay.Results: After adjusting for confounders (age, gender, BMI, and smoking habits), a high negative correlation between depressive and irritable temperament TEMPS-A scores and sVCAM-1 levels was detected. Although we identified no association between sICAM-1 levels and affective temperament scores, sICAM-1 was related to the state severity of manic symptoms. In a multiple linear regression model, sVCAM-1 remained a significant predictor of depressive but not irritable temperament scores.Limitations: The temperaments were estimated on the basis of self-report questionnaire.Conclusions: Our findings suggest that sVCAM-1 is related to affective temperaments, and it is a trait marker for liability to mood disorders. This relationship between alterations in cellular adhesion and affective temperament may be important for vulnerability to affective disorders. [ABSTRACT FROM AUTHOR]

Background: Connective tissue subacromial bursa-derived progenitor cells (SBDCs) have been suggested as a potent biologic augment to promote healing of the repaired rotator cuff tendon. Maximizing the amount of retained progenitor cells at the tendon repair site is essential for ensuring an optimal healing environment, warranting a search for proadhesive and proliferative adjuvants. The purpose was to evaluate the effect of magnesium (Mg), platelet-rich plasma (PRP), and a combination of both adjuvants on the in vitro cellular adhesion and proliferation potential of SBDCs on suture material commonly used in rotator cuff surgery., Methods: SBDCs were isolated from subacromial bursa samples harvested during rotator cuff repair and cultured in growth media. Commercially available collagen-coated nonabsorbable flat-braided suture was cut into 1-inch pieces, placed into 48-well culture dishes, and sterilized under ultraviolet light. Either a one-time dose of 5 mM sterile Mg, 0.2 mL of PRP, or a combination of both adjuvants was added, while a group without treatment served as a negative control. Cellular proliferation and adhesion assays on suture material were performed for each treatment condition., Results: Augmenting the suture with Mg resulted in a significantly increased cellular adhesion (total number of attached cells) of SBDCs compared to PRP alone (31,527 ± 19,884 vs. 13,619 ± 8808; P  < .001), no treatment (31,527 ± 19,884 vs. 21,643 ± 8194; P  = .016), and combination of both adjuvants (31,527 ± 19,884 vs. 17,121 ± 11,935; P  < .001). Further, augmentation with Mg achieved a significant increase in cellular proliferation (absorbance) of SBDCs on suture material when compared to the PRP (0.516 ± 0.207 vs. 0.424 ± 0.131; P  = .001) and no treatment (0.516 ± 0.207 vs. 0.383 ± 0.094; P  < .001) group. The combination of Mg and PRP showed a significantly higher proliferation potential compared to PRP alone (0.512 ± 0.194 vs. 0.424 ± 0.131; P  = .001) and no treatment (0.512 ± 0.194 vs. 0.383 ± 0.094; P  < .001). There were no significant differences in the remaining intergroup comparisons ( P  > .05, respectively)., Conclusion: Augmenting suture material with Mg resulted in a significantly increased cellular adhesion of SBDCs compared to untreated suture material, as well as augmentation with PRP alone or a combination of both adjuvants. Further, Mg with or without PRP augmentation achieved a significant increase in the cellular proliferation of SBDCs on suture material compared to untreated sutures and augmentation with PRP alone. Application of Mg may be a clinically feasible approach to optimizing the use of SBDCs as a biological augment in rotator cuff repair, while combined augmentation with PRP may harness the full potential for optimized tissue recovery due to the high concentration of PRP-derived growth factors., (© 2023 The Author(s).)

Nanocomposites based on superhydrophilic vertically aligned multi-walled carbon nanotubes (VAMWCNT-O2) and nanohydroxyapatite (nHAp) are of great interest in bone regenerative medicine. The biomineralization using simulated body fluid (SBF) has been extensively studied to evaluate the bioactivity of biomaterials. Thus, the combination of nHAp and VAMWCNT-O2 is attractive and promising. The aim of this study was to evaluate the in vitro calcification of nHAp/VAMWCNT-O2 nanocomposites before and after the period of biomineralization in SBF. In vitro calcification of the extracellular matrix (ECM) of HOB cells in culture after 24 hours was investigated through the assay of alkaline phosphatase. These promising in vitro results validate biomineralized nHAp/VAMWCNT-O2 as possible scaffolds for bone tissue regeneration.

This paper describes the functionalization of magnetoelastic (ME) materials with Parylene-C coating to improve the surface reactivity to cellular response. Previous study has demonstrated that vibrating ME materials were capable of modulating cellular adhesion when activated by an externally applied AC magnetic field. However, since ME materials are not inherently biocompatible, surface modifications are needed for their implementation in biological settings. Here, the long-term stability of the ME material in an aqueous and biological environment is achieved by chemical-vapor deposition of a conformal Parylene-C layer, and further functionalized by methods of oxygen plasma etching and protein adsorption. In vitro cytotoxicity measurement and characterization of the vibrational behavior of the ME materials showed that Parylene-C coatings of 10 µm or greater could prevent hydrolytic degradation without sacrificing the vibrational behavior of the ME material. This work allows for long-term durability and functionality of ME materials in an aqueous and biological environment and makes the potential use of this technology in monitoring and modulating cellular behavior at the surface of implantable devices feasible.

Pectin synthesis and modification are vital for plant development, although the underlying mechanisms are still not well understood. Here, we report the functional characterization of the OsTSD2 gene, which encodes a putative methyltransferase in rice. All three independent T-DNA insertion lines of OsTSD2 displayed dwarf phenotypes and serial alterations in different zones of the root. These alterations included abnormal cellular adhesion and schizogenous aerenchyma formation in the meristematic zone, inhibited root elongation in the elongation zone, and higher lateral root density in the mature zone. Immunofluorescence (with LM19) and Ruthenium Red staining of the roots showed that unesterified homogalacturonan (HG) was increased in Ostsd2 mutants. Biochemical analysis of cell wall pectin polysaccharides revealed that both the monosaccharide composition and the uronic acid content were decreased in Ostsd2 mutants. Increased endogenous ABA content and opposite roles performed by ABA and IAA in regulating cellular adhesion in the Ostsd2 mutants suggested that OsTSD2 is required for root development in rice through a pathway involving pectin synthesis/modification. A hypothesis to explain the relationship among OsTSD2, pectin methylesterification, and root development is proposed, based on pectin's function in regional cell extension/division in a zone-dependent manner. [ABSTRACT FROM AUTHOR]

Background and aims ABO blood type is associated with cardiovascular disease, although the underlying mechanisms are presumed to be complex. While the relationship between non-O blood types and von Willebrand Factor (vWF) is well-established, associations with cellular adhesion molecules (CAMs) across diverse populations are understudied. Methods We genetically inferred ABO alleles for N = 6202 participants from the Multi-Ethnic Study of Atherosclerosis. Linear regression was used to evaluate associations between major ABO allele dosages and log-transformed measurements of vWF (N = 924), soluble E-selectin (sE-selectin, N = 925), soluble P-selectin (sP-selectin, N = 2392), and soluble ICAM-1 (sICAM-1, N = 2236) by race/ethnicity. Results For the selectins, the A1 allele was associated with significantly lower levels for all races/ethnicities, with each additional allele resulting in a 28–39% decrease in sE-selectin and 10–18% decrease in sP-selectin relative to Type O subjects. However, the A2 allele demonstrated effect heterogeneity across race/ethnicity for sE-selectin, with lower levels for non-Hispanic whites ( p = 0.0011) but higher levels for Hispanics ( p = 0.0021). We also identified elevated sP-selectin levels for B-allele carriers solely in Hispanic participants ( p = 1.0E-04). ABO-by-race/ethnicity interactions were significant for both selectins ( p < 0.0125). More modest associations were observed between A1 allele dosage and levels of sICAM-1, with ABO alleles explaining 0.8–1.1% of the total phenotypic variation within race/ethnicity. ABO associations with vWF activity were consistent across race/ethnicity, with B allele carriers corresponding to the highest vWF activity levels. Conclusions ABO blood type demonstrates complex associations with endothelial markers that are largely generalizable across diverse populations. [ABSTRACT FROM AUTHOR]

The signaling events that drive familial breast cancer ( FBC) risk remain poorly understood. While the majority of genomic studies have focused on genetic risk variants, known risk variants account for at most 30% of FBC cases. Considering that multiple genes may influence FBC risk, we hypothesized that a pathway-based strategy examining different data types from multiple tissues could elucidate the biological basis for FBC. In this study, we performed integrated analyses of gene expression and exome-sequencing data from peripheral blood mononuclear cells and showed that cell adhesion pathways are significantly and consistently dysregulated in women who develop FBC. The dysregulation of cell adhesion pathways in high-risk women was also identified by pathway-based profiling applied to normal breast tissue data from two independent cohorts. The results of our genomic analyses were validated in normal primary mammary epithelial cells from high-risk and control women, using cell-based functional assays, drug-response assays, fluorescence microscopy, and Western blotting assays. Both genomic and cell-based experiments indicate that cell-cell and cell-extracellular matrix adhesion processes seem to be disrupted in non-malignant cells of women at high risk for FBC and suggest a potential role for these processes in FBC development. [ABSTRACT FROM AUTHOR]

Poly(caprolactone) (PCL) is an attractive biocompatible and biodurable polymer for tissue engineering applications. However, it has limited bioactivity (biomineralization and cellular adhesivity sites).Therefore the aim of this study was to synthesize and characterize PCL-based hollow porous microspheres using a double emulsion-solvent evaporation technique (PVA–PCL–PEG) to improve the biomineralization and cellular adhesivity employing dopamine as a bioactivator. The effect of dopamine-coating on the surface morphology and porosity of the microspheres was evaluated in conjunction with biomineralization testing in simulated body fluids (pH 7.4; 37 °C) over 45 days. The particle size of the microspheres decreased (370–40 µm) with an increase in dopamine concentration. In addition, increased dopamine resulted in higher BET surface area values. The dopamine-coated microspheres exhibited higher biomineralization (Ca–P) as confirmed by chemical structure integrity analysis using FTIR. Ex vivo cell studies revealed superior cellular adhesivity of human dermal fibroblast cells onto the dopamine-coated microspheres. The combined results of this study suggested that the dopamine transformed and bioactivated microspheres may be suitable for advanced tissue engineering applications based on its newly synchronized bioactivation and biodegradation properties. [ABSTRACT FROM AUTHOR]

Enolase is secreted by C. albicans and is present in its biofilms although its extracellular function is unknown. Here we show that extracellular enolase mediates the colonization of small intestine mucosa by C. albicans. Assays using intestinal mucosa disks show that C. albicans adhesion is inhibited, in a dose dependent mode, either by pretreatment of intestinal epithelium mucosa disks with recombinant C. albicans enolase (70% at 0.5 mg/ml enolase) or by pretreatment of C. albicans yeasts with anti-enolase antibodies (48% with 20 µg antiserum). Also using flow cytometry, immunoblots of conditioned media and confocal microscopy we demonstrate that enolase is present in biofilms and that the extracellular enolase is not an artifact due to cell lysis, but must represent functional secretion of a stable form. This is the first direct evidence that C. albicans extracellular enolase mediates colonization on its primary translocation site. Also, because enolase is encoded by a single locus in C. albicans, its dual role peptide, as glycolytic enzyme and extracellular peptide, is a remarkable example of gene sharing in fungi.

Sophisticated drug delivery systems are coated with targeting ligands to improve the specific adhesion to surface receptors on diseased cells. In our study, we developed a method with which we assessed the potential of peptide ligands to specifically bind to receptor overexpressing target cells. Therefore, a microfluidic setup was used where the cellular adhesion of nanoparticles with ligand and of control nanoparticles was observed in parallel under the same experimental conditions. The effect of the ligand on cellular binding was quantified by counting the number of adhered nanoparticles with ligand and differently labeled control nanoparticles on single cells after incubation under flow conditions. To provide easy-to-synthesize, stable and reproducible nanoparticles which mimic the surface characteristics of drug delivery systems and meet the requirements for quantitative analysis, latex beads based on amine-modified polystyrene were used as model nanoparticles. Two short peptides were tested to serve as targeting ligand on the beads by increasing the specific binding to HuH7 cells. The c-Met binding peptide cMBP2 was used for hepatocyte growth factor receptor (c-Met) targeting and the peptide B6 for transferrin receptor (TfR) targeting. The impact of the targeting peptide on binding was investigated by comparing the beads with ligand to different internal control beads: 1) without ligand and tailored surface charge (electrostatic control) and 2) with scrambled peptide and similar surface charge, but a different amino acid sequence (specificity control). Our results demonstrate that the method is very useful to select suitable targeting ligands for specific nanoparticle binding to receptor overexpressing tumor cells. We show that the cMBP2 ligand specifically enhances nanoparticle adhesion to target cells, whereas the B6 peptide mediates binding to tumor cells mainly by nonspecific interactions. All together, we suggest that cMBP2 is a suitable choice for specific receptor targeting whereas the peptide B6 should not be considered as specific targeting moiety. [ABSTRACT FROM AUTHOR]

As ectopic expression of the neuronal inositol-1,4,5-trisphosphate-3-kinase A (InsP 3 Kinase) in tumor cells increases the metastatic potential, InsP 3 Kinase is an interesting target for tumor therapy. Recently, we have identified a membrane-permeable InsP 3 Kinase inhibitor (BAMB-4) exhibiting an IC50-value of 20 μM. Here we characterized a new InsP 3 Kinase inhibitor which shows a 130-fold lower IC50 value (157 ± 57 nM) as compared to BAMB-4. We demonstrate that this nitrophenolic compound, BIP-4, is non-competitive to ATP but competitive to InsP 3 , thus exhibits a high selectivity for inhibition of InsP 3 Kinase activity. Docking analysis suggested a putative binding mode of this molecule into the InsP 3 Kinase active site. Determination of cellular uptake in lung cancer cells (H1299) revealed that 6% of extracellular BIP-4 is internalized by non-endosomal uptake, showing that BIP-4 is not trapped inside endo/lysosomes but is available to inhibit cellular InsP 3 Kinase activity. Interestingly, we found that BIP-4 mediated inhibition of InsP 3 Kinase activity in the two lung cancer cell lines H1299 and LN4323 inhibited proliferation and adhesion at IC50 values of 3 μM or 2 μM, respectively. InsP 3 Kinase inhibition did not alter ATP-induced calcium signals but significantly reduced the level of Ins(1,3,4,5,6)P 5 . From these data we conclude that the inhibitory effect of BIP-4 on proliferation and adhesion of lung cancer cells does not result from alterations of calcium but from alterations of inositol phosphate signals. In summary, we reveal that inhibition of cellular InsP 3 Kinase by BIP-4 impairs proliferation and adhesion and therefore BIP-4 might be a promising compound to reduce the metastatic potential of lung carcinoma cells. [ABSTRACT FROM AUTHOR]

Receptor-ligand bonds are often subjected to forces that regulate their detachment via modulating off-rates. Though the dynamics of detachment is primarily controlled by the physical chemistry of adhesion molecules cellular features such as cell deformability and microvillus viscoelasticity have been shown to have an effect on it as well. In this work, Monte Carlo simulation of the rupture of multiple receptor-ligand bonds between substrate and a polymorphonuclear leukocyte (PMN) cell suspended in a Newtonian fluid is performed. It is demonstrated via various micromechanical models of the PMN cell adhered to the substrate by multiple receptor-ligand bonds that viscous drag caused by relative motion of cell suspended in a Newtonian fluid and cellular viscoelasticity modulate transmission of an applied external load to receptor-ligand bonds. It is demonstrated that due to cellular viscoelasticity the instantaneous intermolecular bond force is lower than the instantaneous applied force. It is also demonstrated that due to cellular viscoelasticity, the mean intermolecular bond rupture forces are lowered while the mean bond lifetime increases. [ABSTRACT FROM AUTHOR]

Structural and quantitative changes in the expression of sialic acid residues on the surface of eukaryotic cells profoundly influence a broad range of biological processes including inflammation, antigen recognition, microbial attachment and tumour metastasis. Uptake and incorporation of sialic acid analogues in mammalian cells enable structure–function studies and perturbation of specific recognition events. Our group has recently shown that a trifluorobutyryl-modified sialic acid metabolite diminishes the adhesion of mammalian cells to E and P-Selectin, presumably by leading to the expression of fluorinated sLe x epitopes on cell surfaces, and interfering with the sLe x –selectin interactions that are well known in mediating tumour cell migration ( J. Med. Chem. 2010 , 53 , 4277). For studies directed towards understanding the molecular basis of this reduced adhesion, chemical synthesis of trifluorobutyrylated sialyl Lewis X (C 4 F 3 -sLe x ) was crucial. We have developed a highly efficient [2+2] approach for the assembly of C 4 F 3 -sLe x on a preparative scale that contains versatile protective groups allowing the glycan to be surface immobilized or solubilized as needed for biophysical studies to investigate selectin interactions. This strategy can, in principle, be used for preparation of other N -modified sLe x analogues. [ABSTRACT FROM AUTHOR]

Abstract: Adhesion and spreading of primary monocytes isolated from human blood were monitored utilizing optical waveguide lightmode spectroscopy (OWLS); a highly sensitive label-free biosensor technique using evanescent optical waves generated at a biocompatible surface. Appropriate development on a custom built setup enabled the OWLS cuvette to be operated as a 1.5ml mini-incubator, controlling both temperature and CO2 levels. The incubator-equipped OWLS is readily applicable for delicate and long-term studies on sensitive primary cells, demonstrated here through monitoring the serum dependence of the adhesion and spreading of human monocytes. Moreover, the custom-built setup enables the simultaneous monitoring of the position and overall width of the OWLS resonant peaks. This unique feature makes it possible to distinguish the refractive index variations induced by the adsorption of secreted material from refractive index changes provoked by cellular spreading. A definite attachment and spreading activity was observed on the substratum (glassy silica–titania), when the serum level of the culturing medium was 0.0–0.01%. Increasing serum concentration resulted in a steep fall in monocyte surface adhesion and spreading. 1.0% serum level practically abolished all spreading activity measured by OWLS, and the number of attached cells was significantly decreased, too. Serum addition to fully spread cells provoked a reduction in the cell–substratum contact area, clearly detectable by the biosensor. Cell spreading was inhibited by pre-coating the sensor surface with considerable amounts of serum proteins. These findings suggest that monocyte spreading is inhibited by the adsorption of serum biomolecules to the substratum, rather than by soluble factors present in the serum. All of these results were obtained completely noninvasively with real time monitoring; demonstrating the capabilities of OWLS to sensitively monitor the adhesion properties of immune cells isolated from human blood. The current study is, therefore, a significant step towards the application of label-free optical biosensors in medical diagnostics. [Copyright &y& Elsevier]

Abstract: Background: There is no doubt that future discoveries in the field of biochemistry will depend on the implementation of novel biosensing techniques, able to record biophysiological events with minimal biological interference. In this respect, organic electronics may represent an important new tool for the analysis of structures ranging from single molecules up to cellular events. Specifically, organic field-effect transistors (OFET) are potentially powerful devices for the real-time detection/transduction of bio-signals. Despite this interest, up to date, the experimental data useful to support the development of OFET-based biosensors are still few and, in particular, n-type (electron-transporting) devices, being fundamental to develop highly-performing circuits, have been scarcely investigated. Methods: Here, films of N,N′-1H,1H-perfluorobutyldicyanoperylene-carboxydi-imide (PDIF-CN2) molecules, a recently-introduced and very promising n-type semiconductor, have been evaporated on glass and silicon dioxide substrates to test the biocompatibility of this compound and its capability to stay electrically-active even in liquid environments. Results: We found that PDIF-CN2 transistors can work steadily in water for several hours. Biocompatibility tests, based on in-vitro cell cultivation, remark the need to functionalize the PDIF-CN2 hydrophobic surface by extra-coating layers (i.e. poly-l-lysine) to favor the growth of confluent cellular populations. Conclusions: Our experimental data demonstrate that PDIF-CN2 compound is an interesting organic semiconductor to develop electronic devices to be used in the biological field. General significance: This work contributes to define a possible strategy for the fabrication of low-cost and flexible biosensors, based on complex organic complementary metal-oxide-semiconductor (CMOS) circuitry including both p- (hole-transporting) and n-type transistors. This article is part of a Special Issue entitled Organic Bioelectronics—Novel Applications in Biomedicine. [Copyright &y& Elsevier]

Abstract: Single molecule force spectroscopy is widely used to determine kinetic parameters of dissociation by analyzing bond rupture data obtained via applying mechanical force to cells, capsules, and beads that are attached to an intermolecular bond. The current analysis assumes that the intermolecular bond force is equal to the externally applied mechanical force. We confirm that viscous drag alone or in combination with cellular deformation resulting in viscoelasticity modulates bond force so that the instantaneous intermolecular bond force is not equivalent to the applied force. The bond force modulation leads to bond rupture time and force histograms that differ from those predicted by probability distribution function (PDF) using the current approach. A new methodology that accounts for bond force modulation in obtaining PDF is presented. The predicted histograms from the new methodology are in excellent agreement with the respective histograms obtained from Monte Carlo simulation. [Copyright &y& Elsevier]

Abstract: Monte Carlo simulation of the rupture of multiple receptor–ligand bonds between two PMN cells suspended in a Newtonian fluid is performed. We demonstrate via micro-mechanical model of two cells adhered by multiple receptor–ligand bonds that viscous drag caused by relative motion of cell suspended in a Newtonian fluid modulates transmission of an applied external load to bonds. Specifically, it is demonstrated that at any time the intermolecular bond force is not equivalent to the instantaneous applied force. The difference in the instantaneous applied force and the intermolecular bond force depends on the viscosity of fluid, the size of cell, the applied loading rate, and the number of bonds at any instant of time. Viscous drag acting on cell reduces average bond rupture forces. [Copyright &y& Elsevier]

Cell-biomaterial interactions can be controlled by modifying the surface chemistry or nanotopography of the material, to induce cell proliferation and differentiation if desired. Here we combine both approaches in forming silk nanofibers (SNFs) containing gold nanoparticles (AuNPs) and subsequently chemically modifying the fibers. Silk fibroin mixed with gold seed nanoparticles was electrospun to form SNFs doped with gold seed nanoparticles (SNFseed). Following gold reduction, there was a 2-fold increase in particle diameter confirmed by the appearance of a strong absorption peak at 525 nm. AuNPs were dispersed throughout the AuNP-doped silk nanofibers (SNFsAu). The Young's modulus of the SNFsAu was almost 70% higher than that of SNFs. SNFsAu were modified with the arginine-glycine-aspartic acid (RGD) peptide. Human mesenchymal stem cells that were cultured on RGD-modified SNFAu had a more than 2-fold larger cell area compared to the cells cultured on bare SNFs; SNFAu also increased cell size. This approach may be used to alter the cell–material interface in tissue engineering and other applications. [ABSTRACT FROM AUTHOR]

Accurate identification of substrates of a protease is critical in defining its physiological functions. We previously predicted that Dsg-2 (desmoglein-2), a desmosomal protein, is a candidate substrate of the transmembrane serine protease matriptase. The present study is an experimental validation of this prediction. As demanded by our published method PNSAS [Prediction of Natural Substrates from Artificial Substrate of Proteases; Venkatraman, Balakrishnan, Rao, Hooda and Pol (2009) PLoS ONE 4, e5700], this enzyme-substrate pair shares a common subcellular distribution and the predicted cleavage site is accessible to the protease. Matriptase knock-down cells showed enhanced immunoreactive Dsg-2 at the cell surface and formed larger cell clusters. When matriptase was mobilized from intracellular storage deposits to the cell surface there was a decrease in the band intensity of Dsg-2 in the plasma membrane fractions with a concomitant accumulation of a cleaved product in the conditioned medium. The exogenous addition of pure active recombinant matriptase decreased the surface levels of immunoreactive Dsg-2, whereas the levels of CD44 and Ecadherin were unaltered. Dsg-2 with a mutation at the predicted cleavage site is resistant to cleavage by matriptase. Thus Dsg- 2 seems to be a functionally relevant physiological substrate of matriptase. Since breakdown of cell-cell contact is the first major event in invasion, this reciprocal relationship is likely to have a profound role in cancers of epithelial origin. Our algorithm has the potential to become an integral tool for discovering new protease-substrate pairs. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the role of CXCL7 in the immune response of human phagocytes against the intracellular bacteria Mycobacterium tuberculosis and Legionella pneumophila. We have observed that polymorphonuclear neutrophil (PMN) chemotaxis induced by the supernatants of infected monocyte derived macrophages (MDM) may be attributed to CXCL8 rather than CXCL7, although both chemokines are present in large quantities. We have also found that CXCL7 is present not only in the supernatants of MDM, but also in the supernatants of PMN of some, but not all, individuals. Western blot analysis revealed that, in both MDM and PMN supernatants appeared two bands with molecular weights consistent with the platelet basic protein (PBP) and the neutrophil activating protein-2 (NAP-2) sizes. Regarding the influence on infected cells, recombinant NAP-2 enhanced the antimicrobial activity of IFNγ activated MDM against L. pneumophila, but not against M. tuberculosis. In addition, U937 cells transfected with a NAP-2 construct inhibited the intracellular multiplication of L. pneumophila, supporting its role in the modulation of the antimicrobial activity. Finally, U937 cells transfected with the NAP-2 construct showed an adherence that was dramatically enhanced when the substrate was fibronectin. We conclude that human phagocytes produce CXCL7 variants that may have a significant influence on the immune response against bacterial pathogens. [Copyright &y& Elsevier]

Abstract: C-type lectins are a superfamily of Ca2+-dependent carbohydrate-recognition proteins which play significant roles as pattern recognition receptors (PRRs) in the innate immunity. In this study, a novel C-type lectin with four dissimilar carbohydrate-recognition domains (CRDs) was identified from Argopecten irradians (designated as AiCTL-9). The full-length cDNA of AiCTL-9 was of 2291bp with an open reading frame of 1827bp encoding a polypeptide of 608 amino acids with a signal sequence and four CRDs. The motifs determining carbohydrate binding specificity in each CRD of AiCTL-9 were different, and they were YPT in CRD1, EPD in CRD2, EPN in CRD3 and QPN in CRD4, respectively. All the four CRDs shared the similar potential tertiary structure of a typical double-loop structure with Ca2+-binding site 2 in the long loop region and two conserved disulfide bridges at the bases of the loops. The mRNA transcripts of AiCTL-9 were mainly detected in hepatopancreas as well as gonad, and also marginally detectable in mantle, adductor, gill and hemocytes. Its relative expression level in hemocytes was significantly up-regulated after the challenges of fungi Pichia pastoris GS115 (P <0.05), Gram-positive bacteria Micrococcus luteus (P <0.05) and Gram-negative bacteria Vibrio anguillarum (P <0.01). The recombinant AiCTL-9 (rAiCTL-9) could bind various PAMPs, including LPS, PGN, mannan and glucan, and also displayed agglutinating activity to fungi P. pastoris GS115, Gram-positive bacteria Bacillus subtilis and Gram-negative bacteria Escherichia coli TOP10F′ as well as V. anguillarum in a Ca2+ dependent manner. Moreover, rAiCTL-9 could initiate the cellular adhesion of hemocytes and enhance their encapsulation in vitro. All these results implied that AiCTL-9 was a novel PRR involved in immune response of scallop against a large number of pathogens by recognizing different PAMPs and enhancing scallop hemocytes encapsulation. [Copyright &y& Elsevier]

This paper describes the functionalization of magnetoelastic (ME) materials with Parylene-C coating to improve the surface reactivity to cellular response. Previous study has demonstrated that vibrating ME materials were capable of modulating cellular adhesion when activated by an externally applied AC magnetic field. However, since ME materials are not inherently biocompatible, surface modifications are needed for their implementation in biological settings. Here, the long-term stability of the ME material in an aqueous and biological environment is achieved by chemical-vapor deposition of a conformal Parylene-C layer, and further functionalized by methods of oxygen plasma etching and protein adsorption. In vitro cytotoxicity measurement and characterization of the vibrational behavior of the ME materials showed that Parylene-C coatings of 10 µm or greater could prevent hydrolytic degradation without sacrificing the vibrational behavior of the ME material. This work allows for long-term durability and functionality of ME materials in an aqueous and biological environment and makes the potential use of this technology in monitoring and modulating cellular behavior at the surface of implantable devices feasible. [ABSTRACT FROM AUTHOR]