Effect of Time and Temperature of Air Jet on the Mechanical and Biological Behavior of a Universal Adhesive System

OBJECTIVES

To evaluate the influence of heat application on the degree of conversion (DC) of the 3M Single Bond Universal Adhesive System, as well as its transdentinal cytotoxicity and microtensile bond strength to dentin.

METHODS

Experimental groups were established according to the time and temperature of the air jet: G1: 5 seconds-25°C; G2: 10 seconds-25°C; G3: 20 seconds-25°C; G4: 5 seconds-50°C; G5: 10 seconds-50°C; G6: 20 seconds-50°C. In control group (G7), no treatment was performed. The DC was assessed using the Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. For the transdentinal cytotoxicity test, dentin discs fitted in artificial pulp chambers (APC) received the application of the adhesive system and the air jets. For the microtensile bond strength, healthy molars were restored and submitted to the microtensile test after 24 hours and 6 months, respectively.

RESULTS

Significant reduction in viability of Mouse Dental Papilla Cell-23 (MDPC-23), which exhibited morphological changes, was observed in all experimental groups compared to control (p<0.05). Although all tested protocols resulted in transdentinal diffusion of 2-hydroxyethyl methacrylate (HEMA), the group G6 presented the highest degree of monomeric conversion and the lowest cytotoxic effect, with higher dentin bond strength values in comparison to group G1 (p<0.05).

CONCLUSIONS

Applying an air blast at 50°C for 20 seconds increases the DC and microtensile bond strength of the 3M Single Bond Universal Adhesive System to dentin, as well as reduces the transdentinal cytotoxicity of the material to pulp cells.

LEF1 supports metastatic brain colonization by regulating glutathione metabolism and increasing ROS resistance in breast cancer

More than half of all brain metastases show infiltrating rather than displacing growth at the macro-metastasis/organ parenchyma interface (MMPI), a finding associated with shorter survival. The lymphoid enhancer-binding factor-1 (LEF1) is an epithelial-mesenchymal transition (EMT) transcription factor that is commonly overexpressed in brain-colonizing cancer cells. Here, we overexpressed LEF1 in an in vivo breast cancer brain colonization model. It shortened survival, albeit without engaging EMT at the MMPI. By differential proteome analysis, we identified a novel function of LEF1 as a regulator of the glutathione (GSH) system, the principal cellular redox buffer. LEF1 overexpression also conferred resistance against therapeutic GSH depletion during brain colonization and improved management of intracellular ROS. We conclude that besides EMT, LEF1 facilitates metastasis by improving the antioxidative capacity of epithelial breast cancer cells, in particular during colonization of the brain parenchyma.

Losses at chromosome 4q are associated with poor survival in operable ductal pancreatic adenocarcinoma

Here we tested the prognostic impact of genomic alterations in operable localized pancreatic ductal adenocarcinoma (PDAC). Fifty-two formalin-fixed and paraffin-embedded primary PDAC were laser micro-dissected and were investigated by comparative genomic hybridization after whole genome amplification using an adapter-linker PCR. Chromosomal gains and losses were correlated to clinico-pathological parameters and clinical follow-up data. The most frequent aberration was loss on chromosome 17p (65%) while the most frequent gains were detected at 2q (41%) and 8q (41%), respectively. The concomitant occurrence of losses at 9p and 17p was found to be statistically significant. Higher rates of chromosomal losses were associated with a more advanced primary tumor stage and losses at 9p and 18q were significantly associated with presence of lymphatic metastasis (chi-square: p = 0.03, p = 0.05, respectively). Deletions on chromosome 4 were of prognostic significance for overall survival and tumor recurrence (Cox-multivariate analysis: p = 0.026 and p = 0.021, respectively). In conclusion our data suggest the common alterations at chromosome 8q, 9p, 17p and 18q as well as the prognostic relevant deletions on chromosome 4q as relevant for PDAC progression. Our comprehensive data from 52 PDAC should provide a basis for future studies with a higher resolution to discover the relevant genes located within the chromosomal aberrations identified.

Seven-fluorochrome mouse M-FISH for high-resolution analysis of interchromosomal rearrangements

The mouse has evolved to be the primary mammalian genetic model organism. Important applications include the modeling of human cancer and cloning experiments. In both settings, a detailed analysis of the mouse genome is essential. Multicolor karyotyping technologies have emerged to be invaluable tools for the identification of mouse chromosomes and for the deciphering of complex rearrangements. With the increasing use of these multicolor technologies resolution limits are critical. However, the traditionally used probe sets, which employ 5 different fluorochromes, have significant limitations. Here, we introduce an improved labeling strategy. Using 7 fluorochromes we increased the sensitivity for the detection of small interchromosomal rearrangements (700 kb or less) to virtually 100%. Our approach should be important to unravel small interchromosomal rearrangements in mouse models for DNA repair defects and chromosomal instability.

[Direct molecular analysis of single disseminated cancer cells: a prerequisite for the development of adjuvant therapies?]

Cancer mortality has only marginally decreased in the last decades despite huge diagnostic and therapeutic efforts. Early dissemination of cancer cells has to be blamed for this finding, because ectopically residing cells are necessarily left behind by the surgeon. Consequently, this cell population has been designated as minimal residual disease that may eventually lead to systemic relapse months or years after presumed curative surgery. Paradoxically, systemic adjuvant treatments are currently administered without any precise knowledge about the target population of such drugs. Here it is argued that the direct analysis of disseminated cells may be a prerequiste for the development of future therapies since first molecular genetic data of single disseminated cancer cells suggest an excessive intercellular heterogeneity and distant relationship to the primary tumor.

[From single disseminated tumor cells to metastasis insights from molecular genetic analyses of single cells]

The prevailing models of cancer metastasis postulate that, after a series of accumulating genetic and epigenetic changes during transformation and invasive growth, the most advanced clone within a primary tumour acquires the critical cellular phenotype enabling dissemination and metastasis. This postulate is particularly based on observations that metastases usually display more genetic changes than the primary tumour. The development of several novel techniques is now enabling experimental testing of the model: The detection of single disseminated cancer cells by epithelial specific antibodies directed against cytokeratin in mesenchymal tissues has become possible even before manifestation of metastasis. After their isolation by micromanipulation comprehensive amplification of the single cell genomes allows the application of several molecular genetic methods for further characterisation. Our first data from single cytokeratin-positive cells that were isolated from the bone marrow of breast cancer patients indicate that the model of cancer progression should be revised. Cancer cells already disseminate in an early stage of genomic development and still have to acquire the critical chromosomal aberrations needed for metastatic outgrowth and full malignant potential. These observations apparently imply consequences for the development of novel adjuvant therapies. The early diversification of primary tumours and disseminated cancer cells precludes a simple extrapolation from local to systemic disease eventually necessitating increasing efforts for the direct analysis of single disseminated cancer cells as the cellular targets of adjuvant therapies.

Early cancer cell dissemination and late metastatic relapse: clinical reflections and biological approaches to the dormancy problem in patients

Two clinical entities, unknown-primary cancer and inadvertent transmission of cancer with organ transplants are reviewed and discussed in the context of early and occult tumor cell dissemination. Both entities are taken as chief witnesses for cell dissemination being an early event in tumor progression. The involuntary transmission of tumor by organ grafts directly supports the notion that very few quiescent cells lodging at improbable sites such as kidney or heart suffice to generate de novo metastatic disease in the organ recipient. As to the nature of the cells and their biological and clinical significance a short review is given on the detection of disseminated cells in bone marrow and their prognostic significance for a metastatic relapse in patients with resected primary tumors. A novel single-cell genomic analysis is described, that allows the detection of multiple chromosomal aberration in single tumor cells.

Transcriptome analysis reveals a role of interferon-gamma in human neointima formation

The most effective immediate cure for coronary stenosis is stent-supported angioplasty. Restenosis due to neointima proliferation represents a major limitation. We investigated the expression of 2435 genes in atherectomy specimens and blood cells of patients with restenosis, normal coronary artery specimens, and cultured human smooth muscle cells (SMCs). Of the 223 differentially expressed genes, 37 genes indicated activation of interferon-gamma (IFN-gamma) signaling in neointimal SMCs. In cultured SMCs, IFN-gamma inhibited apoptosis. Genetic disruption of IFN-gamma signaling in a mouse model of restenosis significantly reduced the vascular proliferative response. Our data suggest an important role of IFN-gamma in the control of neointima proliferation.

Gene expression profiling of human stent-induced neointima by cDNA array analysis of microscopic specimens retrieved by helix cutter atherectomy: Detection of FK506-binding protein 12 upregulation

BACKGROUND

Restenosis due to neointima formation is the major limitation of stent-supported balloon angioplasty. Despite abundant animal data, molecular mechanisms of neointima formation have been investigated on only a limited basis in patients. This study sought to establish a method for profiling gene expression in human in-stent neointima and to identify differentially expressed genes that may serve as novel therapeutic targets.

METHODS AND RESULTS

We retrieved tissue specimens from patients with symptomatic in-stent restenosis using a novel helix cutter atherectomy device. cDNA samples prepared from neointima (n=10) and, as a control, from the media of normal arteries (n=14) were amplified using a novel polymerase chain reaction protocol and hybridized to cDNA arrays. Immunohistochemistry characterized the atherectomy material as neointima. cDNA arrays readily identified differentially expressed genes. Some of the differentially expressed genes complied with expected gene expression patterns of neointima, including downregulation of desmin and upregulation of thrombospondin-1, cyclooxygenase-1, and the 70-kDa heat shock protein B. Additionally, we discovered previously unknown gene expression patterns, such as downregulation of mammary-derived growth inhibitor and upregulation of FK506-binding protein 12 (FKBP12). Upregulation of FKBP12 was confirmed at the protein level in neointimal smooth muscle cells.

CONCLUSIONS

Gene expression patterns of human neointima retrieved by helix-cutter atherectomy can be reliably analyzed by cDNA array technology. This technique can identify therapeutic targets in patients, as exemplified by the findings regarding FKBP12. FKBP12 is the receptor for Rapamycin (sirolimus), which in animal models reduced neointima formation. Our study thus yields a rationale for the use of Rapamycin to prevent restenosis in patients.

Determining spatial modes of lasers with spatial coherence measurements

We explain a technique that extracts both the structure and the modal weights of spatial modes of lasers by analyzing the spatial coherence of the beam. This is the first time, to our knowledge, that an experimental method is being used to measure arbitrary forms of the spatial modes. We applied this method to an edge-emitting Fabry-Perot semiconductor laser with a stripe width of 5 mum and extracted fundamental and first-order lateral modes with relative power weights of 96.2% and 3.8%. There was a single transverse mode.

The biology and analysis of single disseminated tumour cells

Despite an increasing molecular-genetic understanding of the development of malignant epithelial neoplasias, the frontline therapy for patients with carcinomas is still surgery. Systemic adjuvant treatments such as chemotherapy or immunotherapy have had limited success perhaps because they are based on analysis of the primary tumour or on cell lines derived from metastasis. However, the characteristics of systemically disseminated tumour cells can be very different from that of the primary tumour or end-stage metastasis. Consequently, there is a need to study the evolution and nature of systemic cancer directly in order to identify new target structures for therapy present on the potential precursors of metastasis--the disseminated tumour cells.

Comparative genomic hybridization, loss of heterozygosity, and DNA sequence analysis of single cells

A PCR strategy is described for global amplification of DNA from a single eukaryotic cell that enables the comprehensive analysis of the whole genome. By comparative genomic hybridization, not only gross DNA copy number variations, such as monosomic X and trisomic 21 in single male cells and cells from Down's syndrome patients, respectively, but multiple deletions and amplifications characteristic for human tumor cells are reliably retrieved. As a model of heterogeneous cell populations exposed to selective pressure, we have studied single micrometastatic cells isolated from bone marrow of cancer patients. The observed congruent pattern of comparative genomic hybridization data, loss of heterozygosity, and mutations as detected by sequencing attests to the technique's fidelity and demonstrates its usefulness for assessing clonal evolution of genetic variants in complex populations.

Optically produced true-time delays for phased antenna arrays

A device is described for generating true-time delays optically for microwave signals used in beam steering and beam shaping in phased-array antennas. The device can be adapted to provide delays from picoseconds to nanoseconds. A single, compact unit should provide parallel delays for more than 64 independent antenna elements with a greater than 6-bit resolution. The time delays are produced by multiple reflections in a mirror configuration with continuous refocusing. A single spatial light modulator selects independent optical path lengths for each of the parallel antenna elements. Amplitude control for beam shaping can be integrated into the device. The unit can be made rugged for harsh environments by use of solid-block construction. The operation of the true-time delay device is described, along with the overall system configuration. Preliminary experimental data are given.

The p2 domain of human immunodeficiency virus type 1 Gag regulates sequential proteolytic processing and is required to produce fully infectious virions

The proteolytic processing sites of the human immunodeficiency virus type 1 (HIV-1) Gag precursor are cleaved in a sequential manner by the viral protease. We investigated the factors that regulate sequential processing. When full-length Gag protein was digested with recombinant HIV-1 protease in vitro, four of the five major processing sites in Gag were cleaved at rates that differ by as much as 400-fold. Three of these four processing sites were cleaved independently of the others. The CA/p2 site, however, was cleaved approximately 20-fold faster when the adjacent downstream p2/NC site was blocked from cleavage or when the p2 domain of Gag was deleted. These results suggest that the presence of a C-terminal p2 tail on processing intermediates slows cleavage at the upstream CA/p2 site. We also found that lower pH selectively accelerated cleavage of the CA/p2 processing site in the full-length precursor and as a peptide primarily by a sequence-based mechanism rather than by a change in protein conformation. Deletion of the p2 domain of Gag results in released virions that are less infectious despite the presence of the processed final products of Gag. These findings suggest that the p2 domain of HIV-1 Gag regulates the rate of cleavage at the CA/p2 processing site during sequential processing in vitro and in infected cells and that p2 may function in the proper assembly of virions.

Surface and bulk absorption characteristics of chemically vapor-deposited zinc selenide in the infrared

<p>Chemically vapor-deposited zinc selenide exhibits outstanding properties in the infrared and has been established as a prime material for transmissive optics applications. Here we present and discuss data relating to the surface and the bulk absorption forward-looking infrared- (FLIR-) grade chemically vapor-deposited ZnSe, at wavelengths (2-20 µm) and temperatures (100-500 K) of current interest.</p><p>This investigation is based on both spectral emittance measurements and infrared transmission spectroscopy performed in the context of a systems development program. Surface effects can be detected at wavelengths of up to 14 µm and usually predominate at wavelengths of less than 8 µm. Fractional surface absorptions are temperature independent from approximately 200 to 400 K and can be fitted to a Fourier series, at wavelengths ranging from 3.5 to 13.5 µm. The bulk absorption coefficient (βv) is strongly dependent on temperature as well as wavelength, but it can be approximated by a bivariate polynomial expressin that yields recommended values. At wavelengths λ ≲ 10 µm, βv decreases with increasing temperature; it is shown that a wavelength-independent Debye-Waller factor provides a correct description of the temperature dependence, thus pointing to infrared-active localized modes. At wavelengths λ ≳ 14 µm, βv increases with temperature and exhibits temperature dependencies (T(1.7), T(2.6)) that reflect three- and four-phonon summation processes. Finally, an analysis of the temperature dependence of βv at 10.6 µm demonstrates that the intrinsic lattice dynamical contribution to bulk absorption at this wavelength should be close to 4 × 10(-4) cm(-1), in accord with the results of earlier laser calorimetry tests performed on exceptionally pure laser-grade chemically vapor-deposited ZnSe.</p>

TNF-alpha and cyclooxygenase metabolites do not modulate C. albicans septic shock with disseminated candidiasis

We analyzed differences in host regulation of tumor necrosis factor-alpha (TNF-alpha) production and pathophysiological responses in conscious rats after infection with two strains of pathogenic Candida albicans spp. (CA-1 and CA-2) compared with Escherichia coli serotype 055:B5 (EC). The hypothesis was tested that, in contrast to EC, hypotension, organ injury, and mortality after candidemia are not obligatorily dependent on TNF-alpha or TNF-alpha-induced cyclooxygenase pathway metabolites. Dose, viability, and strain-specific dependencies were established after intravenous 10(6) or 10(9) viable CA, as well as heat-killed (HK) or Formalin-inactivated (FI) CA blastospores, compared with live EC at the 24-h LD25 [10(9) colony-forming units (CFU)] and LD100 (10(10) CFU). Shock without endotoxemia developed 4-8 h after 10(9) live CA-1 or CA-2 (LD100 at 24 h) with disseminated yeast-mycelial transformation and increased microvascular permeability in multiple organs but not after HK or FI CA-1. Peak serum TNF-alpha after an LD100 of CA-1 or CA-2 was < 3% of LD25 EC values and was < 1% of peak values during lethal bacteremia. Similar pathogen-specific differences were found in liver- and lung-associated TNF. Production of functionally inactive TNF-alpha during candidemia was excluded by enzyme-linked immunosorbent assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis with Western blotting. Passive immunization against TNF-alpha 2 h before microbial challenge was not protective against CA but prevented otherwise lethal EC sepsis. Cyclooxygenase inhibition also failed to attenuate candidemic shock. We conclude that the magnitude and kinetics of TNF-alpha production and TNF-alpha-dependent immunophysiological responses are differentially regulated after lethal fungal vs. gram-negative bacterial infection. Thus TNF-alpha is not a pivotal mediator of the acute Candida septic shock syndrome with disseminated candidiasis.

Differential systemic and intrapulmonary TNF-alpha production in Candida sepsis during immunosuppression

Candida albicans (CA) increasingly causes septic shock, acute lung injury, and multiple organ damage during immunosuppression-related neutropenia. However, the effects of neutrophil (PMN) depletion on induction of tumor necrosis factor-alpha (TNF) by CA and its potential mediation of Candida septic shock are unknown. We hypothesized that reduced CA uptake by circulating PMNs during cyclophosphamide (CY)-related neutropenia sensitizes to TNF-mediated shock from enhanced cytokine production after phagocytosis by tissue macrophages. Absolute or relative neutropenia (PMNs < or = 500/microliters or 2,500/microliters) was modeled in rats by intraperitoneal CY 4-8 days before 10(9) yeast-phase CA (acute studies < or = 24 h, n = 81 animals) or 10(6) CA (subacute studies < or = 72 h, n = 25). Compared with neutrophil-sufficient rats, absolute neutropenia accelerated hemodynamic collapse and respiratory distress after 10(9) CA, and pulmonary microvascular permeability was amplified. These changes evolved without increased candidemia or elevations in bioactive or antigenic serum TNF, which remained low even at death (42.3 +/- 14.8 U/ml vs. 12.6 +/- 2.9 U/ml for CY + saline, means +/- SE, P = NS). In contrast, significant TNF in lung tissue and bronchoalveolar lavage fluid (BALF) was evident within 6 h in CY + 10(9) CA rats. Electron microscopy confirmed hyphal proliferation into alveoli from yeast within mononuclear cells in lung capillaries. Subacute disseminated candidiasis after 10(6) CA was not associated with elevated serum, lung, or BALF TNF. We conclude that differential systemic and intrapulmonary TNF production occur in CA septic shock during preexisting neutropenia, with compartmentalized TNF production in the lower respiratory tract accompanying yeast-mycelial transformation. Thus TNF is not an obligate mediator of acute candidemic shock or subacute disseminated candidiasis during CY-induced immunosuppression but may initiate pulmonary injury accompanying high-grade candidemia.

Power handling capability of Faraday rotation isolators for CO(2) laser radars

Faraday rotation isolators for CO(2) laser radars must be capable of handling substantial average power loads without degrading the beam quality or experiencing thermal runaway. For this reason, the semiconductorbased isolators, which are of promise for applications at 10.6 microm, must be cooled. This creates radial temperature gradients and, in conjunction with a nonuniform beam pattern, may lead to severe wavefront aberrations. It is the purpose of this paper to formulate simple procedures for assessing the impact of such aberrations in a cw regime and to provide a prescription on how to proceed in the context of designing or evaluating Faraday rotators for CO(2) laser systems. If it is a good approximation to describe the beam-induced temperature rise by means of a fourth-order even polynomial, the degradation in beam quality originates entirely from the quartic term deltaT(4)rho(4). Specifically, it is the spherical aberration factor S = deltaT(4) radicalvar[rho(4)] that best describes the combined impact of temperature profile and beam shape. The heat flow equation for cw-loaded, edge-cooled, or face-cooled cylindrical Faraday rotator elements can be formulated in a simple nondimensional manner, which demonstrates that (a) temperature variations causing optical distortion scale with betaP/K, i.e., linearly with the deposited power per unit path length and inversely with the thermal conductivity; (b) in a transmission mode of operation with edge cooling and no thermal runaway, the power handling capability is independent of the aperture diameter; and (c), in a double-pass reflection mode of operation that takes advantage of a face-cooled back surface, a significant reduction of the distortion requires Nusselt numbers of at least 10, which leads to a new figure of merit for characterizing the performance of Faraday rotator material candidates. Edge-cooled optical isolators described in the published literature then provide cases for exercising the formalism and demonstrating its effectiveness. Finally, the authors examine the InSb free-carrier Faraday rotator developed at Case Western Reserve University and evaluate its surface-cooling requirement in light of specific design objectives.

Distance distortions in children's cognitive maps: an examination of the information storage model

Second graders (mean age = 7-8), fourth graders (mean age = 9-8), and sixth graders (mean age = 11-11) walked two paths located in and around their school. Children in the Unsegmented condition estimated the distance and time taken to walk a path that was relatively undifferentiated in terms of the number of qualitatively different areas of the school through which it passed. Children in the Segmented condition made the same estimates for a path that went through different areas (segments) of the school (i.e., cafeteria, hall, vestibule, and outside the building). Children at all three grade levels estimated that the distance traversed in the Segmented condition was longer than the distance in the Unsegmented condition. This difference was not significant on the time measure. It was concluded that (1) paths with a large number of segments are perceived as being longer than paths of the same length with fewer segments, (2) distances along paths with few segments are underestimated, (3) distances along paths with many segments may be overestimated as a function of developmental level, and (4) only younger children may have used time to estimate distance.