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Background: The mechanisms of neointima formation after synthetic vascular grafting are not clear. The aim of this study was to investigate the intima and perigraft adventitia remodeling process in terms of cell apoptosis versus proliferation after synthetic patch implantation. Methods: Female Merino sheep were randomized equally into two groups and underwent implantion with a patch of gelatin sealed Dacron graft into the left common carotid artery. At 1 and 6 months, grafted vessels were harvested, processed, and assessed. Intimal area and lumen sizes were measured with histologic assessment of eight segments from each animal assisted with image analysis. Immunohistochemical labeling of α-actin and D33 desmin was performed on tissue sections of perigraft adventitia, graft matrix, and intima. Cell proliferation and cell phenotype were determined with double immunohistochemical staining with anti-proliferating cell nuclear antigen and anti-α-actin or antimacrophage antibodies (HAM 56) in perigraft adventitia, graft matrix, and intima. Apoptosis was detected with in situ terminal deoxynucleiotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate-fluorescence nick end labeling (TUNEL) in perigraft adventitia, graft matrix, and intima. Results: The carotid artery lumen size at 6 months was significantly larger than at 1 month (P ≤ .05). The intimal area was significantly reduced at 6 months compared with 1 month (P < .05). At 1 month and 6 months, perigraft adventitia, graft matrix, and intima showed positive α-actin expression but negative desmin staining. In the anastomotic area, a small number of intimal cells suggested their muscle origin (expression α-actin and desmin). The number of proliferating cells in the intima was significantly greater at 1 month than at 6 months (P = .01). TUNEL-positive cells were significantly greater in the intima at 1 month than at 6 months (P < .05), whereas TUNEL-positive cells were significantly greater at 6 months in the perigraft adventitia (P < .05). HAM 56-positive cells in the intima at 1 month were significantly greater compared with 6 months (P < .05), whereas in graft and perigraft regions, no significant difference was seen between 1 month and 6 months. Conclusion: The cell proliferation and cell phenotype change in intima and perigraft adventitia are associated with thickening of perigraft adventitia and intima at 1 month. The balance between cell proliferation and apoptosis could account in part for the reduction in intima area and perigraft adventitial cellularity at 6 months. (J Vasc Surg 2002;36:371-8.)

Disruption of gap junctional communication (GJC) by various compounds, including growth factors and tumor promoters, is believed to be modulated by the phosphorylation of a gap junctional protein, connexin43 (Cx43). We have previously demonstrated a platelet-derived growth factor (PDGF)-induced blockade of GJC and phosphorylation of Cx43 in T51B rat liver epithelial cells expressing wild-type PDGF receptor beta (PDGFr beta). Both of these actions of PDGF required participation of protein kinase C (PKC) and mitogen-activated protein kinase (MAPK). Similar requirements of MAPK were suggested in the modulation of GJC by other agents, including epidermal growth factor (EGF) and lysophosphatidic acid (LPA). Since many of these agents activate additional protein kinases, our present study examined whether activation of MAPK was sufficient for Cx43 phosphorylation and GJC blockade. By utilizing a variety of MAPK activators, we now show that activation of MAPK is not always associated with either Cx43 phosphorylation or disruption of GJC, which suggests a requirement for additional factors. Furthermore, pretreatment with hydrogen peroxide (H2O2), a potent MAPK activator but inefficient GJC/Cx43 modulator, abrogated PDGF- or TPA-induced disruption of GJC. While a 5 min H2O2 pretreatment abolished both PDGF- and TPA-induced Cx43 phosphorylation and GJC blockade, a simultaneous H2O2 treatment interfered only with GJC closure but not with the phosphorylation of Cx43 induced by PDGF and TPA. This finding indicates that, in addition to the Cx43 phosphorylation step, inhibition of GJC requires interaction with other components. H2O2-mediated abrogation of PDGF/TPA signaling can be neutralized by the antioxidant N-acetylcysteine (NAC) or by the tyrosine kinase inhibitor genistein. Taken together, our results suggest that disruption of GJC is not solely mediated by either activated MAPK or Cx43 phosphorylation but requires the participation of additional kinases and regulatory components. This complex mode of regulation is perhaps essential for the proposed functional role of GJC.

The platelet-derived growth factor (PDGF) mediates its cellular functions via activation of its receptor tyrosine kinase followed by the recruitment and activation of several signaling molecules. These signaling molecules then initiate specific signaling cascades, finally resulting in distinct physiological effects. To delineate the PDGF signaling pathway responsible for the disruption of gap junctional communication (GJC), wild-type PDGF receptor beta (PDGFRbeta) and a series of PDGFRbeta mutants were expressed in T51B rat liver epithelial cells. In cells expressing wild-type PDGFRbeta, PDGF induced disruption of GJC and phosphorylation of a gap junctional protein, connexin-43 (Cx43), which required activation of mitogen-activated protein kinase, although involvement of additional factors was also evident. In the F5 mutant lacking binding sites for phosphatidylinositol 3-kinase, GTPase-activating protein, SHP-2, and phospholipase Cgamma1 (PLCgamma1), PDGF induced mitogen-activated protein kinase, but failed to affect GJC or Cx43, indicating involvement of additional signals presumably initiated by one or more of the mutated binding sites. Examination of the single-site mutants revealed that PDGF effects were not mediated via a single signaling component. This was confirmed by the "add-back" mutants, which showed that restoration of either SHP-2 or PLCgamma1 binding was sufficient to propagate the GJC inhibitory actions of PDGF. Further analysis showed that activation of PLCgamma1 is involved in Cx43 phosphorylation, which surprisingly failed to correlate with GJC blockade. The results of our study demonstrate that PDGF-induced disruption of GJC can be mediated by multiple signaling pathways and requires participation of multiple components.

Background Gap junctional communication (GJC) has been implicated in the control of cell proliferation. Numerous cancer cells show a decrease or loss of GJC compared to their normal counterparts. Lack of adequate information on the status of gap junctions during prostate neoplasia prompted us to examine this form of cancer, which comprises about 14% of male cancer deaths in America. Methods Cultured normal human prostate epithelial cells and several different human prostate tumor lines were used in this study. GJC was assayed by dye transfer, whereas Western blot and immunofluorescence methods were used to examine connexin43 (Cx43) levels and the presence of gap junctions, respectively. Results Normal human prostate cultures exhibited extensive cell-communication which was completely absent in all the examined tumor cells. This disrupted communication was associated with a decreased expression and an impaired posttranslational modification of Cx43 in these cells. Abundant immunostaining of gap junctional channels by a Cx43-antibody was observed in normal prostate cells but not in tumor cells. Conclusions Our data provide further support for the hypothesis that loss of junctional communication is a critical step in progression to human prostate neoplasia.

Previously we showed a rapid and transient inhibition of gap junctional communication (GJC) by platelet-derived growth factor (PDGF) in T51B rat liver epithelial cells expressing wild-type platelet-derived growth factor beta receptors (PDGFrbeta). This action of PDGF correlated with the hyperphosphorylation of the gap junction protein connexin43 (Cx43) and required PDGFrbeta tyrosine kinase activity, suggesting the participation of protein kinases and phosphatases many of which are activated by PDGF treatment. In the present study, two such kinases, namely protein kinase C (PKC) and mitogen-activated protein kinase (MAPK), are investigated for their possible involvement in PDGF-induced closure of junctional channels and Cx43-phosphorylation. Down-regulation of PKC-isoforms by 12-O-tetradecanoylphorbol-13-acetate or pretreatment with the PKC inhibitor calphostin C, completely blocked PDGF action on GJC and Cx43. Activation of MAPK correlated with PDGF-induced Cx43 phosphorylation, and prevention of MAPK activation by PD98059 eliminated the PDGF effects. Interestingly, elimination of GJC recovery by cycloheximide was associated with a sustained activated-MAPK level. Based on these results we postulate that the activation of PKC and MAPK are required in PDGF-mediated Cx43 phosphorylation and junctional closure.

Gap junctional communication (GJC) between contacting cells has been postulated to be involved in the regulation of cell proliferation. This suggestion stems from numerous studies showing modulation of GJC by agents that influence cellular proliferation. Platelet-derived growth factor (PDGF), a strong mitogen, inhibits GJC in many cell types. To understand the molecular nature of the signal transduction pathway responsible for the GJC blockade, T51B rat liver epithelial cells, which lack endogenous PDGF receptor (PDGFr), were infected with a retrovirus containing either wild-type full-length cDNA of human PDGFrβ (Kin+) or a mutant PDGFrβ lacking receptor tyrosine kinase activity (Kin−). PDGF caused a complete but transient interruption of cell communication in Kin+ cells within 15–20 min of addition. This interruption of GJC was not associated with a gross destabilization of gap junction plaques but with the phosphorylation of connexin43 (Cx43), the only known gap junction protein expressed in these cells. These effects were not exhibited in either control T51B cells or in Kin− cells, indicating a requirement of the receptor tyrosine kinase activity. Further examination revealed that the newly phosphorylated Cx43 then undergoes a rapid degradation utilizing the lysosomal pathway resulting in a decreased total Cx43 protein level. The re-establishment of GJC following PDGF treatment was dependent on protein synthesis. This report describes a suitable cell system which is currently being utilized for the characterization of the PDGF signaling pathway responsible for the inhibition of GJC. J. Cell. Physiol. 174:66–77, 1998. © 1998 Wiley-Liss, Inc.

With the increase of temperature in flow field,gas molecules possess not only rotational degree of freedom,but also vibrational energy excitation.In order to simulate and study the influence of internal energy excitation on polyatomic gas flow with high temperature and high Mach number,according to the general Boltzmann equation,we consider the rotational and vibrational energy modes as the independent variables of gas molecular velocity distribution function.It is assumed that the rotational and vibrational energy modes are described by continuous distribution with degree of freedom and temperature.Based on the Borgnakke-Larsen collision model used in direct simulation Monte Carlo (DSMC) method, the collision term of Boltzmann equation with internal energy excitation is divided into elastic and inelastic collision terms.The inelastic collision is decomposed into translational-rotational energy relaxation and translational-rotationalvibrational energy relaxation according to a certain relaxation rate obtained from the reciprocalities of rotational and vibrational collisions numbers per one elastic collision.Then a kind of Boltzmann model equation considering the excitation of vibrational energy is constructed.For showing the consistency between the present model equation and Boltzmann equation,the conservation of summational invariants and the H-theorem of this model are proved.When solving the present model equation with numerical methods,because of the continuous energy modes,it is difficult to simulate this model equation directly.In this paper,three control equations are derived and solved by the LU-SGS (lower-upper symmetric Gauss-Seidel) method,and the cell-centered finite volume method with multi-block patched grid technique in physical space.As a result,these gas-kinetic unified algorithm (GKUA) with vibrational energy excitation has been developed.Results are presented for N2 with different Knudsen numbers around cylinder from continuum to rarefied gas flow by using the present Boltzmann model equation,GKUA with simple gas model,and DSMC method. Very good agreement between the present model and DSMC results is obtained,which shows that the accuracy and reliability of the present model.Comparing the translational,rotational,vibrational,and total temperatures computed by different methods,the effects of the rotational and vibrational degrees of freedom are demonstrated.For the simple gas model,the translational temperature is much higher than those for the other two models with internal energy excitation. At the same time,the distance from shock wave to wall for the simple gas model is about twice those for the other two models.On the other hand,the obtained aerodynamic force coefficients of the cylinder are increasing according to the sequence from the simple gas model to the rotational energy excitation model to the vibrational energy excitation model, but the variation range is very small.By reducing the gas characteristic vibrational temperature,the temperature after the shock wave is much lower,and the heat flux declines evidently at the stagnation point with the same temperature as the wall temperature.This implies that with the wall temperature increasing the heat flux declines.

The existing machine-vision surface roughness measurement technique extracts relevant evaluation indices from grayscale images without using the strong sensitivity of color information. In addition, most of these measurements use a micro-vision imaging method to measure a small area and cannot make an overall assessment of the workpiece's surface. To address these issues, a method of measuring surface roughness that uses an ordinary light source and a macro-vision perspective to generate a red and green color index for each pixel is proposed in the present study. A comparison test is conducted on a set of test samples before and after surface contamination using the color index and gray-level algebraic averaging, the square of the main component of the Fourier transform in the frequency domain, and the entropy. A strong correlation between the color index and the surface roughness is established; this correlation is not only higher than that of other indices but also present despite contamination and very robust. Verification using a regression model based on a support vector machine proves that the proposed method not only has a simple apparatus and makes measurement easy but also provides high precision and is suitable over a wide measurement range. The impact of the red and green color blocks, the lighting, and the direction of the surface texture on the correlation between the color index and the roughness are also assessed and discussed in this paper.

In the digital signal processing, the NCO (Numerically Controlled Oscillators) has a wide range of applications. In this paper, we have researched and implemented the NCO based on the lookup table algorithm with the VHDL and the ISE tool of Xilinx Inc. Finally, the simulation results indicate that the designed NCO is suitable.

How to solve hypersonic aerothermodynamics and complex flow mechanism covering various flow regimes from high rarefied free-molecular flow of outer-layer space to continuum flow of near-ground is one of the frontier basic problems in the field of fluid physics. In this work, the unified Boltzmann model equation based on the molecular velocity distribution function is presented for describing complex hypersonic flow transport phenomena covering all flow regimes by physics analysis and model processing of the collision integral to the Boltzmann equation. The discrete velocity ordinate method is developed to simulate complex flows from low Mach numbers to hypersonic flight, and the gas-kinetic coupling-iteration numerical scheme is constructed directly to solve the evolution and updating of the molecular velocity distribution function by employing the unsteady time-splitting method and the NND finite-difference technique. Then, the gas-kinetic unified algorithm (GKUA) is presented to~simulate the three-dimensional hypersonic aerothermodynamics and flow problems around space vehicles covering various flow regimes from free-molecule to continuum. To verify the accuracy and reliability of the present GKUA and simulate gas thermodynamic transport phenomena covering various flow regimes, firstly, the two-dimensional supersonic flows around a circular cylinder are simulated in the continuum regime of Kn= 0.0001 and in the high rarefied regime of Kn= 0.3 through the comparison between the Navier-Stokes (N-S) solution and the direct simulation Monte Carlo (DSMC) result, respectively. It is indicated that the GKUA can exactly converge to the N-S solution in the continuum flow regime, and the computed results of the GKUA are consistent with the DSMC simulation with a small deviation of 0.45% in the high rarefied flow regime. Then, the three-dimensional complex hypersonic flows around reusable satellite shape are studied as one of the engineering applications of the GKUA with a wide range 0.002 Kn 1.618 of the free-stream Knudsen numbers and different Mach numbers during re-entering Earth atmosphere with the flying altitudes of 110-70~km. The computed results are found to be in high resolution of the flow fields and in good agreement in a deviation range of 0.27%-8.56% by comparison among the relevant reference data, DSMC and theoretical predictions. The complex flow mechanism, flow phenomena and changing laws of hypersonic aerothermodynamics are revealed for spacecraft re-entry into the atmosphere, and the effects of rarefied gas and wall temperature on the aerothermodynamics characteristics of re-entry satellite shape are compared and analysed with different Knudsen numbers and wall temperature ratios of Tw/T = 1.6, 10 and 15.6. It is validated that the non-dimensional heat flux coefficient in the rarefied transitional flow regime is higher than that of the continuum and near-continuum flow regimes, the high wall temperature results in the enlarging amplitude of temperature variation on the stagnation line and the serious effect on the heat flux of the stagnation point, and wall temperature becomes lower, the heat flux coefficient of wall surface becomes bigger, and the friction force and pressure coefficients decrease. The non-equilibrium level of flow velocity slip and temperature jump on the surface of space vehicle becomes severer, and the stronger heat transfer effect between the space vehicle and the gas flow is produced as the Mach number or Knudsen number of the free-stream flow increases. It can be realized from this study that the gas-kinetic unified algorithm directly solving the Boltzmann model velocity distribution function equation may provide an important and feasible way that complex hypersonic aerothermodynamic problems and flow mechanisms from high rarefied free-molecule to continuum flow regimes can be solved effectively and reliably.

PIN 2019 Competition, sixth in a series of IPIN competitions, was held at the CNR Research Area of Pisa (IT), integrated into the program of the IPIN 2019 Conference. It included two on-site real-time Tracks and three off-site Tracks. The four Tracks presented in this paper were set in the same environment, made of two buildings close together for a total usable area of 1000 m 2 outdoors and and 6000 m 2 indoors over three floors, with a total path length exceeding 500 m. IPIN competitions, based on the EvAAL framework, have aimed at comparing the accuracy performance of personal positioning systems in fair and realistic conditions: past editions of the competition were carried in big conference settings, university campuses and a shopping mall. Positioning accuracy is computed while the person carrying the system under test walks at normal walking speed, uses lifts and goes up and down stairs or briefly stops at given points. Results presented here are a showcase of state-of-the-art systems tested side by side in real-world settings as part of the on-site real-time competition Tracks. Results for off-site Tracks allow a detailed and reproducible comparison of the most recent positioning and tracking algorithms in the same environment as the on-site Tracks.