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Communicative & Integrative Biology Jul 2012mDia proteins are members of the formin family of actin nucleating proteins that polymerize linear actin filaments. Such filaments form the core of thin, tubular,...
mDia proteins are members of the formin family of actin nucleating proteins that polymerize linear actin filaments. Such filaments form the core of thin, tubular, membrane-bound cell surface protrusions known as filopodia, which are a major feature of mammalian cell morphology. Filopodia are dynamic structures that help cells sense environmental cues, and play a role in cell migration, axon guidance, angiogenesis and other processes. RhoGTPases bind to and control the activity of mDia proteins, and several other binding partners of the three mDia1 isoforms-mDia1, mDia2 and mDia3-have been documented. Two independent pathways controlling mammalian filopodium formation have emerged, with one driven by the RhoGTPase Cdc42, and the other by Rif. While mDia2 has been the main formin implicated in forming filopodia, mDia1 has recently surfaced as the key formin utilized by both the Cdc42 and Rif pathways to drive filopodial protrusion.
PubMed: 23060957
DOI: 10.4161/cib.20214 -
Gut Microbes 2024(), a gram-positive anaerobic and spore-forming bacterium, is the leading cause of nosocomial antibiotic-associated diarrhea in adults which is characterized by high...
(), a gram-positive anaerobic and spore-forming bacterium, is the leading cause of nosocomial antibiotic-associated diarrhea in adults which is characterized by high levels of recurrence and mortality. Surface (S)-layer Protein A (SlpA), the most abundantly expressed protein on the bacterial surface, plays a crucial role in the early stages of infection although the nature of its involvement in physiology is yet to be fully understood. Anti-S-layer antibodies have been identified in the sera of convalescent patients and have been correlated with improved outcomes of infection (CDI). However, the precise mechanisms by which anti-S-layer antibodies confer protection to the host remain unknown. In this study, we report the first monoclonal antibodies (mAbs) targeting the S-layer of reference strain 630. Characterization of these mAbs unraveled important roles for the S-layer protein in growth, toxin secretion, and biofilm formation by , with differential and even opposite effects of various anti-SlpA mAbs on these functions. Moreover, one anti-SlpA mAb impaired growth and conferred sensitivity to lysozyme-induced lysis. The results of this study show that anti-S-layer antibody responses can be beneficial or harmful for the course of CDI and provide important insights for the development of adequate S-layer-targeting therapeutics.
Topics: Adult; Humans; Antibodies, Monoclonal; Clostridioides difficile; Gastrointestinal Microbiome; Cell Death
PubMed: 38289292
DOI: 10.1080/19490976.2023.2301147 -
Entropy (Basel, Switzerland) Feb 2023In this work, the balance equations of non-equilibrium thermodynamics are coupled to Galilean limit systems of the Maxwell equations, i.e., either to (i) the...
In this work, the balance equations of non-equilibrium thermodynamics are coupled to Galilean limit systems of the Maxwell equations, i.e., either to (i) the quasi-electrostatic limit or (ii) the quasi-magnetostatic limit. We explicitly consider a volume Ω, which is divided into Ω+ and Ω- by a possibly moving singular surface , where a charged reacting mixture of a viscous medium can be present on each geometrical entity (Ω+,S,Ω-). By the restriction to the Galilean limits of the Maxwell equations, we achieve that only subsystems of equations for matter and electromagnetic fields are coupled that share identical transformation properties with respect to observer transformations. Moreover, the application of an entropy principle becomes more straightforward and finally helps estimate the limitations of the more general approach based the full set of Maxwell equations. Constitutive relations are provided based on an entropy principle, and particular care is taken in the analysis of the stress tensor and the momentum balance in the general case of non-constant scalar susceptibility. Finally, we summarise the application of the derived model framework to an electrochemical system with surface reactions.
PubMed: 36981305
DOI: 10.3390/e25030416 -
Proceedings of the National Academy of... Apr 2021The problem of extracting the three-dimensional (3D) shape and material properties of surfaces from images is considered to be inherently ill posed. It is thought that a...
The problem of extracting the three-dimensional (3D) shape and material properties of surfaces from images is considered to be inherently ill posed. It is thought that a priori knowledge about either 3D shape is needed to infer material properties, or knowledge about material properties are needed to derive 3D shape. Here, we show that there is information in images that cospecify both the material composition and 3D shape of light permeable (translucent) materials. Specifically, we show that the intensity gradients generated by subsurface scattering, the shape of self-occluding contours, and the distribution of specular reflections covary in systematic ways that are diagnostic of both the surface's 3D shape and its material properties. These sources of image covariation emerge from being causally linked to a common environmental source: 3D surface curvature. We show that these sources of covariation take the form of "photogeometric constraints," which link variations in intensity (photometric constraints) to the sign and direction of 3D surface curvature (geometric constraints). We experimentally demonstrate that this covariation generates emergent cues that the visual system exploits to derive the 3D shape and material properties of translucent surfaces and demonstrate the potency of these cues by constructing counterfeit images that evoke vivid percepts of 3D shape and translucency. The concepts of covariation and cospecification articulated herein suggest a principled conceptual path forward for identifying emergent cues that can be used to solve problems in vision that have historically been assumed to be ill posed.
PubMed: 33811143
DOI: 10.1073/pnas.2024798118 -
Acta Histochemica Et Cytochemica Apr 2023SARS-CoV-2 infects a variety of tissues, including the oral cavity. However, there are few reports examining the association of SARS-CoV-2 with tongue mucosal tissues...
SARS-CoV-2 infects a variety of tissues, including the oral cavity. However, there are few reports examining the association of SARS-CoV-2 with tongue mucosal tissues with sticky tongue debris. This study investigated the presence of SARS-CoV-2 and its associated molecules by dissecting tongue tissue from autopsy specimens of 23 patients who died of COVID-19-related illness (pneumonia). Immunohistochemical staining, electron microscopy, and PCR analysis were performed on the tongue tissue specimens. The mucosal epithelium of the tongue formed a very thick keratinized with well-developed filiform papillae in all cases. ACE2 and TMPRSS2 were consistently co-expressed in all samples in the epithelium. The S-protein was strongly expressed in basal cells and the epithelial surface. S-protein-positive viral particles were detected in the tongue's stratified squamous epithelium via an immunoelectron microscope. Based on PCR amplification of the N1 and N2 regions, the SARS-CoV-2 gene was detected on the tongue epithelium, tongue submucosa, and in tongue debris. This suggests that tongue debris, including the squamous epithelial tissue, could be a source of SARS-CoV-2 in saliva. Furthermore, removing tongue debris may decrease the amount of SARS-CoV-2 in the oral cavity.
PubMed: 37124954
DOI: 10.1267/ahc.22-00089 -
Biology of Sex Differences Jul 2018Osseointegration is dependent on the implant surface, surrounding bone quality, and the systemic host environment, which can differ in male and female patients. Titanium...
BACKGROUND
Osseointegration is dependent on the implant surface, surrounding bone quality, and the systemic host environment, which can differ in male and female patients. Titanium (Ti) implants with microstructured surfaces exhibit greater pullout strength when compared to smooth-surfaced implants and exhibit enhanced osteogenic cellular responses in vitro. Previous studies showed that 1α,25-dihydroxyvitamin D3 [1α,25(OH)D] has a greater effect on rat osteoblast differentiation on microstructured Ti compared to smooth Ti surfaces and tissue culture polystyrene (TCPS). The stimulatory effect of 17β-estradiol (E) on differentiation is observed in female osteoblasts on micro-rough Ti, but it is not known if male osteoblasts behave similarly in response to E and microtopography. This study assessed whether human male and female osteoblasts exhibit sex-specific differences in response to E and 1α,25(OH)D when cultured on microstructured Ti surfaces.
METHODS
Osteoblasts from three male and three female human donors were cultured on Ti discs with varying surface profiles: a smooth pretreatment (PT), a coarse grit-blasted/acid-etched (SLA), and an SLA surface having undergone modification in a nitrogen environment and stored in saline to maintain hydrophilicity (modSLA). Cells cultured on these surfaces were treated with E or 1α,25(OH)D.
RESULTS
Male and female human osteoblasts responded similarly to microstructure although there were donor-specific differences; cell number decreased, and osteocalcin (OCN), osteoprotegerin (OPG), and latent and active transforming growth factor 1 increased on SLA and modSLA compared to TCPS. Female osteoblasts had higher alkaline phosphatase activity and OCN production than male counterparts but produced less OPG. Both sexes responded similarly to 1α,25(OH)D. E treatment reduced cell number and increased osteoblast differentiation and factor production only in female cells.
CONCLUSIONS
Male and female human osteoblasts respond similarly to microstructure and 1α,25(OH)D but exhibit sexual dimorphism in substrate-dependent responses to E. E affected female osteoblasts, suggesting that signaling is sex-specific and surface-dependent. Donor osteoblasts varied in response, demonstrating the need to test multiple donors when examining human samples. Understanding how male and female cells respond to orthopedic biomaterials will enable greater predictability post-implantation as well as therapies that are more patient-specific.
Topics: Biocompatible Materials; Cells, Cultured; Estradiol; Estrogens; Humans; Osteoblasts; Osteocalcin; Osteoprotegerin; Sex Characteristics; Surface Properties; Titanium; Vitamin D
PubMed: 29970177
DOI: 10.1186/s13293-018-0190-x -
Biomedical Optics Express Nov 2022We present the formulation of a paraxial ray transfer or ABCD matrix for onion-type GRIN lenses. In GRIN lenses, each iso-indicial surface (IIS) can be considered a...
We present the formulation of a paraxial ray transfer or ABCD matrix for onion-type GRIN lenses. In GRIN lenses, each iso-indicial surface (IIS) can be considered a refracting optical surface. If each IIS is a shell or layer, the ABCD matrix of a GRIN lens is computed by multiplying a typically high number of translation and refraction matrices corresponding to the K layers inside the lens. Using a differential approximation for the layer thickness, this matrix product becomes a sum. The elements , , , and of the approximated GRIN ray transfer matrix can be calculated by integrating the elements of a single-layer matrix. This ABCD matrix differs from a homogeneous lens matrix in only one integration term in element , corresponding to the GRIN contribution to the lens power. Thus the total GRIN lens power is the sum of the homogeneous lens power and the GRIN contribution, which offers a compact and simple expression for the ABDC matrix. We then apply this formulation to the crystalline lens and implement both numerical and analytical integration procedures to obtain the GRIN lens power. The analytical approximation provides an accurate solution in terms of Gaussian hypergeometric functions. Last, we compare our numerical and analytical procedures with published ABCD matrix methods in the literature, and analyze the effect of the iso-indicial surface's conic constant () and inner curvature gradient () on the lens power for different lens models.
PubMed: 36733757
DOI: 10.1364/BOE.466374 -
The Journal of Advanced Prosthodontics Jun 2014This study focused on in vitro cell differentiation and surface characteristics in a magnesium coated titanium surface implanted on using a plasma ion source.
PURPOSE
This study focused on in vitro cell differentiation and surface characteristics in a magnesium coated titanium surface implanted on using a plasma ion source.
MATERIALS AND METHODS
40 commercially made pure titanium discs were prepared to produce Ti oxide machined surface (M) and Mg-incorporated Ti oxide machined surface (MM). Surface properties were analyzed using a scanning electron microscopy (SEM). On each surface, alkaline phosphatase (ALP) activity, alizarin red S staining for mineralization of MC3T3-E1 cells, and quantitative analysis of osteoblastic gene expression, were evaluated. Actin ring formation assay and gene expression analysis of TRAP and GAPDH performing RT-PCR were performed to characterize osteoclast differentiation on mouse bone marrow-derived macrophages (BMMs).
RESULTS
MM showed similar surface morphology and surface roughness with M, but was slightly smoother after ion implantation at the micron scale. M was more hydrophobic than MM. No significant difference between surfaces on ALP activity at 7 and 14 days were observed. Real-time PCR analyses showed similar levels of mRNA expression of the osteoblast phenotype genes; osteopontin (OPN), osteocalcin (OCN), bone sialoprotein (BSP), and collagen 1 (Col 1) in cell grown on MM at 7, 14 and 21 days. Alizarin red S staining at 21 days showed no significant difference. BMMs differentiation increased in M and MM. Actin ring formation assay and gene expression analysis of TRAP showed osteoclast differentiation to be more active on MM.
CONCLUSION
Both M and MM have a good effect on osteoblastic cell differentiation, but MM may speed the bone remodeling process by activating on osteoclast differentiation.
PubMed: 25006378
DOI: 10.4047/jap.2014.6.3.157 -
Materials (Basel, Switzerland) Jan 2023Fiber can absorb asphalt binder and therefore reinforce and stabilize the asphalt mixture structure and also prevent the asphalt from the leaking, which occurs in the...
Fiber can absorb asphalt binder and therefore reinforce and stabilize the asphalt mixture structure and also prevent the asphalt from the leaking, which occurs in the process of mixing and transport. In this study, three kinds of fiber (polyester fiber, polypropylene fiber, and lignin fiber) are used to evaluate the relationship between the fiber types and mechanic performance of SMA-13 fiber asphalt mixture, which is specially designed for field tests of high-speed vehicles on pavements. The micro-surface characteristics of fiber and aggregates were studied by SEM and image analysis. Marshall stability and splitting strength were used to measure the properties of the asphalt mixture. In addition, a field test, including measures for curve-section edge, curve-section center, straight-section edge, and straight-section center, was conducted to evaluate the skid resistance of the high-speed vehicles that test field pavement. The results show that the Marshall stabilities of asphalt mixture with three kinds of fibers have been improved, whereas the stability of asphalt mixture prepared by polypropylene fiber and polyester fiber particularly increased before immersion. Among the three kinds of fiber asphalt mixtures, the polyester fiber asphalt mixture has enhanced water susceptibility. Skid resistance in the field test indicated that high skid resistance and good surface-texture depth were achieved.
PubMed: 36676286
DOI: 10.3390/ma16020549 -
Optics Express May 2022We present a tunable on-chip liquid resonator in conjunction with a tapered fiber coupling scheme. The resonator consists of a glycerol droplet submerged within an...
We present a tunable on-chip liquid resonator in conjunction with a tapered fiber coupling scheme. The resonator consists of a glycerol droplet submerged within an immiscible liquid bath, which mitigates the effects of environmental fluctuations. The platform is fabricated using standard semiconductor techniques, which enable the future integration of photonic components for an on-chip liquid resonator device. The liquid resonator maintains its high Q-factor on chip (10) due to surface tension forming an atomically smooth liquid-liquid interface. Higher Q-factor resonance modes experienced linewidth broadening due to the random excitation of thermal capillary vibrations. Spectral tuning is demonstrated using the electrowetting effect, increasing the surface's wettability and an expansion in the droplet diameter. A maximum spectral tuning of 1.44 nm ± 5 pm is observed by applying 35 V. The tuning range is twice the free spectral range (FSR) of 0.679 nm measured at a pumping wavelength range of 770-775 nm. A 2D axisymmetric finite-element simulation shows resonance modes in good agreement with experimentally measured spectra and with predicted tuning speeds of 20 nm/s.
PubMed: 36221684
DOI: 10.1364/OE.455536