Disentangling Origins of Adhesive Bonding at Interfaces between Epoxy/Amine Adhesive and Aluminum.

Joining metals by adhesive bonding is essential in widespread fields such as mobility, dentistry, and electronics. Although adhesive technology has grown since the 1920s, the roles of interfacial phenomena in adhesive bonding are still elusive, which hampers the on-demand selection of surface treatment and adhesive types. In the present study, we clarified how chemical interactions and mechanical interlocking governed adhesive bonding by evaluating adhesion properties at the interfaces between epoxy/amine adhesive and two kinds of Al adherends: a flat aluminum hydroxide (AlxOyHz) and technical Al plate with roughness. Spectroscopic and microscopical data demonstrate that the protonation of the amino groups in an amine hardener converts Al(OH)3 on the AlxOyHz surface to AlO(OH). The interfacial protonation results in an interfacial dipole layer with positive charges on the adhesive side, whose electrostatic interaction increases the interfacial fracture energy. The double cantilever beam tests for the flat AlxOyHz and technical Al substrates clarify that the mechanical interlocking originating from the surface roughness further increases the fracture energy. This study disentangles the roles of the chemical interactions and mechanical interlocking occurring at the epoxy adhesive/Al interface in the adhesion mechanism.

Simulation Study of the Effect of Nanoporous Surfaces on the Adhesion Properties of Cross-Linked Polymer Networks.

We have investigated the effect of surface nanopores on the adhesion behavior between cross-linked polymer networks and metal substrates by molecular dynamics simulations. By increasing the cross-linking ratio of the polymer network, the fracture behavior in tensile mode changed from cohesive failure to interfacial failure. In the case of polymers without cross-links, the breaking strengths were almost the same for systems with flat and porous metal substrates. Conversely, in the case of cross-linked polymer networks, the tensile behavior for the porous metal substrates depended on the cross-linking ratio and structure of the polymer chains. For polymer networks consisting of long polymer chains, the force curves in extension mode before the yield points were almost the same for the systems regardless of the surface roughness caused by nanopores. Meanwhile, for highly cross-linked resin networks consisting of short rigid molecules, the yielding strength of the porous metal surfaces showed slightly higher values than that of the flat metal surfaces. The simulation results revealed that the adhesion behavior between cross-linked polymer networks and rough metal surfaces is related not only to the interfacial area but also to the detailed networking topology of the polymers.

Mutations to the probe of Cobas TaqMan HIV-1 ver. 1.0 assay causing undetectable viral load in a patient with acute HIV-1 infection.

We encountered a human immunodeficiency virus (HIV)-1 in which the viral load was undetectable with the Cobas TaqMan HIV-1 ver. 1.0 (CTM v.1.0) in a patient with acute HIV-1 infection. The CTM v.1.0 assay showed more than 1,000-fold underestimation compared with the subsequent Cobas Amplicor Monitor v.1.5 assay. Because five mismatches to the CTM v.1.0 assay probe in the HIV-1 virus in the patient were disclosed by the manufacturer, partial gag regions of the HIV genome were directly sequenced from the patient's plasma viral RNA. The detected single nucleotide point mutations were located near the 5'-end of the Cobas Amplicor Monitor probe. Clinicians should be very careful in making interpretations when indeterminate Western blot analysis results and a low or even undetectable HIV-1 viral load are encountered with the CTM HIV-1 ver. 1.0 assay in patients with suspected acute HIV infection. Repeating Western blot analysis is essential before considering a low HIV-1 viral load to be a false-positive result.

Simulation Study of the Effects of Interfacial Bonds on Adhesion and Fracture Behavior of Epoxy Resin Layers.

The adhesion and fracture behavior of tetraglycidyl-4,4'-diaminodiphenylmethane (TGDDM)/4,4'-diaminodiphenyl sulfone (44DDS)-bisphenol A diglycidyl ether (DGEBA)/44DDS layer interfaces were investigated by molecular dynamics (MD) simulation, mainly focusing on the role of covalent and noncovalent interactions. To accurately investigate the bond dissociation processes, the force field parameters of several bond potentials of the epoxy resin polymers were optimized by density functional theory calculations. In the MD simulations under a tensile load, small voids gradually developed without covalent bond dissociation in the plateau region. In the final large strain region, the stress rapidly increased with bond breaking, leading to failure. When the chemical bonds across the interface between the two layers were removed, the stress-strain curve in the initial elastic region was almost the same as that with interfacial bonds. This showed that the nonbonded interactions governed adhesion strength in the initial elastic region. In contrast, the bonded interactions at interfaces played important roles in the hardening regions because the bonded interactions made the major contribution to the fracture energies. We also investigated the effect of the etherification reaction in cross-linking. It was found that the etherification reaction mainly contributed to the behavior in the late region with large strain. These simulation results revealed that the nonbonded interactions, especially, van der Waals interactions, are important factors for adhesion of the different polymer layers in the small strain region up to the yield point.

Methylation of multiple genes as molecular markers for diagnosis of a small, well-differentiated hepatocellular carcinoma.

The current study was conducted to identify robust methylation markers and their combinations that may prove useful for the diagnosis of early hepatocellular carcinoma (HCC). To achieve this, we performed in silico CpG mapping, direct sequencing and pyrosequencing after bisulfite treatment, and quantitative methylation-specific PCR (MSP) in HCC and non-HCC liver tissues. In the filtering group (25 HCCs), our direct sequencing analysis showed that, among the 12 methylation genes listed by in silico CpG mapping, 7 genes (RASSF1A, CCND2, SPINT2, RUNX3, GSTP1, APC and CFTR) were aberrantly methylated in stages I and II HCCs. In the validation group (20 pairs of HCCs and the corresponding non-tumor liver tissues), pyrosequencing analysis confirmed that the 7 genes were aberrantly and strongly methylated in early HCCs, but not in any of the corresponding non- tumor liver tissues (p < 0.00001). The results obtained using our novel quantitative MSP assay correlated well with those observed using the pyrosequencing analysis. Notably, in MSP assay, RASSF1A showed the most robust performance for the discrimination of HCC and non-HCC liver tissues. Furthermore, a combination of RASSF1A, CCND2 and SPINT2 showed 89-95% sensitivity, 91-100% specificity and 89-97% accuracy in discriminating between HCC and non-HCC tissues, and correctly diagnosed all early HCCs. These results indicate that the combination of these 3 genes may aid in the accurate diagnosis of early HCC.

Inactivation of cholinesterase induced by non-steroidal anti-inflammatory drugs with horseradish peroxidase: implication for Alzheimer's disease.

AIMS: To clarify the mechanism of the protective effect of non-steroidal anti-inflammatory drugs (NSAIDs) on Alzheimer's disease, inactivation of cholinesterase (ChE) induced by NSAIDs was examined. MAIN METHODS: Equine ChE and rat brain homogenate were incubated with NSAIDs and horseradish peroxidase (HRP) and H(2)O(2) (HRP-H(2)O(2)). ChE activity was measured by using 5,5'-dithiobis(nitrobenzoic acid). By using electron spin resonance, NSAID radicals induced by reaction with HRP-H(2)O(2) were detected in the presence of spin trap agents. KEY FINDINGS: Equine ChE was inactivated by mefenamic acid with HRP-H(2)O(2). ChE activity in rat brain homogenate decreased dependent on the concentration of mefenamic acid in the presence of HRP-H(2)O(2). NSAIDs diclofenac, indomethacin, phenylbutazone, piroxicam and salicylic acid inactivated ChE. Oxygen radical scavengers did not prevent inactivation of ChE induced by mefenamic acid with HRP-H(2)O(2). However, spin trap agents 5,5-dimethyl-1-pyrroline-l-oxide and N-methyl-nitrosopropane, reduced glutathione and ascorbic acid strongly inhibited inactivation of ChE, indicating participation of mefenamic acid radicals. Fluorescent emission of ChE peaked at 400 nm, and the Vmax value of ChE changed during interaction of mefenamic acid with HRP-H(2)O(2), indicating that ChE may be inactivated through modification of tyrosine residues by mefenamic radicals. SIGNIFICANCE: The protective effect of NSAIDs on Alzheimer's disease seems to occur through inactivation of ChE induced by NSAIDs radicals.

Attentional processing of location and color cues during driving.

Studies have shown that prior information concerning the spatial location of a subsequent target facilitates the selection of that target for further visual processing in three-dimensional (3-D) space. Using Posner's cuing paradigm, our work examined the reaction time of drivers when cue duration and peripheral environment luminance was changed, and explored the effect color and location on reaction time. Experiment 1 showed that reaction time was not affected by cue duration, and that shifts of attention operated more efficiently for cue location validity. Experiment 2 showed that there was no main effect of background luminance on reaction time. Experiment 3 showed that location produces a greater effect than color.

Effect of fixation point distances on allocation of attention in real three-dimensional space.

Although variation in spatial relations between observer and objects is important when attention functions in three-dimensional space, the effects of changes in spatial relations on attention in real three-dimensional space are still unclear. In Exp. 1, the effects of varying distances of the fixation point on attention in a spatial cuing paradigm were investigated. In Exp. 2, the effects of increase in task demand were examined by making observers detect a blinking fixation point, while performing the same task as in Exp. 1. In both experiments, attention could be manipulated by a precue when the fixation-point distance changed from trial to trial, and in Exp. 2 distribution of attention was manipulated by perceptual load. These findings together indicate that allocation of attentional resources in three-dimensional space varies by task demand.

Simulation Study of the Effects of Nanoporous Structures on Mechanical Properties at Polymer-Metal Interfaces.

We investigated the effect of nanopores on the adhesion behavior at polymer-metal interfaces by molecular dynamics simulation. The effects of shear and extension behavior were examined. In the shear mode, samples with porous substrates showed larger shear forces than those with flat substrates. Meanwhile, the breaking strengths in the extension mode were almost the same for systems with flat and porous substrates. The similar behavior in the extension mode was ascribed to the formation of voids in the polymer layer, which was related to the increase of total system volume and not affected by the presence of pores. We also investigated the relationship between the mechanical properties of polymer-metal interfaces in the shear mode and pore size in detail. Even a very shallow pore with a depth of 0.5 nm produced a large shear force comparable to that of a pore with a depth of 2.0 nm. The shear force increased gradually as the pore diameter became wider. These simulation results revealed that the adhesion forces between polymers and rough metal surfaces are not simply related to the interface area but depend on the pulling mode, pore size, and polymer chain length in a complicated manner.

Urinary adiponectin as a new diagnostic index for chronic kidney disease due to diabetic nephropathy.

Objective: The chronic kidney disease (CKD) is widely diagnosed on the basis of albuminuria and the glomerular filtration rate. A more precise diagnosis of CKD, however, requires the assessment of other factors. Urinary adiponectin recently attracted attention for CKD assessment, but evaluation is difficult due to the very low concentration of urinary adiponectin in normal subjects. Research design and methods: We developed an ultrasensitive ELISA coupled with thionicotinamide-adenine dinucleotide cycling to detect trace amounts of proteins, which allows us to measure urinary adiponectin at the subattomole level. We measured urinary adiponectin levels in 59 patients with diabetes mellitus (DM) and 24 subjects without DM (normal) to test our hypothesis that urinary adiponectin levels increase with progression of CKD due to DM. Results: The urinary adiponectin levels were 14.88±3.16 (ng/mg creatinine, mean±SEM) for patients with DM, and 3.06±0.33 (ng/mg creatinine) for normal subjects. The threshold between them was 4.0 ng/mg creatinine. The urinary adiponectin levels increased with an increase in the CKD risk. Furthermore, urinary adiponectin mainly formed a medium-molecular weight multimer (a hexamer) in patients with DM, whereas it formed only a low-molecular weight multimer (a trimer) in normal subjects. That is, the increase in urinary adiponectin in patients with DM led to the emergence of a medium-molecular weight form in urine. Conclusions: Our new assay showed that urinary adiponectin could be a new diagnostic index for CKD. This assay is a non-invasive test using only urine, thus reducing the patient burden.

Identification of novel aberrant methylation of BASP1 and SRD5A2 for early diagnosis of hepatocellular carcinoma by genome-wide search.

A genome-wide study using expression profiles of 12,600 genes was conducted to identify methylated genes that could be used for early diagnosis of hepatocellular carcinoma (HCC). Of the 12,600 genes examined, we identified 23 genes with significantly lower expression levels in HCC tissues than in non-HCC liver tissues by our statistical and CpG mapping tests. Of these 23 genes, methylation analysis by direct sequencing with bisulfite treatment determined 4 genes that were aberrantly methylated in 20 HCC samples of TNM stages I and II. Further methylation analysis of the 4 genes by quantitative sequencing with 20 HCCs and the corresponding non-tumor liver tissues from an independent cohort of HCC patients revealed that 2 genes, BASP1 and SRD5A2, were aberrantly methylated in only HCC tissues, though not in any corresponding non-tumor liver tissues. Notably, in the cohort we found that BASP1 or SRD5A2 were aberrantly methylated when a cut-off value of 30% in the methylation rate was used, in all cases of 11 HCCs of TNM stages I and II, of 10 well-differentiated HCCs and of 4 small HCCs <2 cm in maximum diameter, but in none of the 20 corresponding non-HCC livers. Methylation-specific PCR for BASP1 and SRD5A2 reproduced the same results observed by direct sequencing. These results indicate that BASP1 and SRD5A2 might serve as useful biomarkers for early diagnosis of HCC.

Relation between serum levels of cell-free DNA and inflammation status in hepatitis C virus-related hepatocellular carcinoma.

Our study revealed that the level of circulating cell-free DNA (cfDNA) is increased in the serum of patients with hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC). To gain insight into the mechanism underlying this phenomenon, we examined the association between cfDNA levels and various clinicopathological factors in 96 patients with HCV-related HCC and 99 non-HCC patients with HCV. Using pooled DNA microarray data, we profiled the expression patterns of inflammatory cytokine genes in 14 primary tumors from the group of HCC patients. We found that there were positive associations between the cfDNA level, aspartate aminotransferase levels and the number of leukocytes and neutrophils in patients with HCV-related HCC but not in non-HCC patients with HCV. The serum cfDNA level was not associated with other clinicopathological factors in HCC or non-HCC patients. A cluster analysis based on the inflammatory cytokine gene data revealed that HCCs with a high serum cfDNA level had increased levels of several inflammatory cytokine genes, suggesting that the serum cfDNA level is associated with the inflammatory status in primary tumors in HCV-related HCC.

Individual differences in the radiosensitivity of hematopoietic progenitor cells detected in steady-state human peripheral blood.

The aim of this study is to evaluate the individual differences in radiosensitivity of lineage-committed myeloid hematopoietic progenitors, colony-forming cells (CFC), detected in steady-state human peripheral blood (PB). Mononuclear cells were prepared from the buffy-coat of 30 individuals PB, and were assayed for CFC by semi-solid culture supplemented with cytokines. X irradiation was performed in the range of 0.5-4 Gy at a dose rate of about 80 cGy/min. The mean number of hematopoietic progenitor cells is 5866 alpha 3408 in 1 ml of buffy-coat, suggesting that the erythroid progenitor cells are the major population. The total CFC radiosensitivity parameter D(0) and n value are 1.18 alpha 0.24 and 1.89 alpha 0.98, respectively. Using a linear regression analysis, a statistically significant correlation is observed between the D(0) value and the surviving fraction at 4 Gy (r = 0.611 p < 0.001). Furthermore, we evaluate the relationship between individual radiosensitivity and the level of antioxidants, plasma uric acid, plasma bilirubin, and intracellular glutathione. No statistically significant correlations are observed, however, between the D(0) parameter and the level of antioxidants, plasma uric acid, plasma bilirubin, and intracellular glutathione. The present study demonstrates that there are large individual differences in the radiosensitivity of hematopoietic progenitor cells as detected in steady-state human PB. These differences demonstrate almost no correlation with plasma or intracellular antioxidants. The prediction of individual differences in radiosensitivity of CFC can only be measured by 4 Gy irradiation.

Allocation of attention and effect of practice on persons with and without mental retardation.

Persons with mild and moderate mental retardation and CA-matched persons without mental retardation performed a dual-task, "pencil-and-paper task" (Baddeley, Della Sala, Gray, Papagno, & Spinnler (1997). Testing central executive functioning with a pencil-and-paper test. In Rabbit (Ed.), Methodology of Frontal and Executive Function (pp. 61-80). Hove, East Sussex, UK: Psychology Press), which includes a memory span task and a tracking task. The memory span task loads onto phonological working memory and the tracking task loads onto visuo-spatial working memory. By comparing performance between single and dual-task, we assessed the characteristics of executive function, which allocates attentional resources between two tasks. Results indicate that there was no difference in the characteristics between the two groups, and there was no improvement in the characteristics with practice. Thus, we suggest that when persons with mental retardation perform a dual-task that have no interference in the sub-storage of working memory, their function of attentional allocation can work without impairment.

Molecular dynamics study of crystallization of polymer systems confined in small nanodomains.

We study the ordering dynamics of polymer crystallization using molecular dynamics simulations, in which the polymers are confined to small nanodomains surrounded by a noncrystalline medium. Although the adsorption process and surface diffusion of polymer chains play a major role in the case of the crystalline interface, the domain interface which consists of noncrystalline medium does not have such a crystal substrate to induce the growth of a crystal layer, which may lead to different ordering dynamics. We found that existence of a noncrystalline domain interface has two opposite effects. In the case of semiflexible polymer systems, the domain interface accelerates crystallization in the initial period, whereas it suppresses crystallization in the intermediate or late period. When the rigidity of polymer chains increases, the acceleration effect of the initial crystallization induced by the domain interface is sometimes hidden by spontaneous homogeneous nucleation. These ordering behaviors can be explained by the restriction on the local chain direction near the domain surface in the crystal nucleation stage and the restriction of large orientation relaxation and coalescence in the crystal growth stage. Simulation results reveal that the confinement by the noncrystalline medium does not have a simple effect on the polymer crystallization dynamics, but has various conflicting effects combined with the time stage, the rigidity of polymer chains, and the strength of the surrounding domain interface.

[Metabolism of non-steroidal anti-inflammatory drugs by peroxidase: implication for gastrointestinal mucosal lesions].

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to treat inflammatory diseases including rheumatoid arthritis and gout. The anti-inflammatory action of NSAIDs is due to the inhibition of prostaglandin synthesis by preventing cyclooxygenase (COX) activity of prostaglandin H synthase (PGS). However, administration of NSAIDs causes gastrointestinal mucosal lesions and a decrease of granulocytes as side effects. PGS catalyzes two distinct enzyme reactions: (1) bis-dioxygenation of arachidonic acid catalyzed by COX activity of PGS to form PGG(2); and (2) reduction of the hydroperoxide group in PGG(2) by PGS hydroperoxidase. Most NSAID are oxidized by peroxidases to produce NSAID radicals that damage biological components such as lipids and enzymes. Indomethacin, phenylbutazone, and piroxicam are more toxic under aerobic conditions than anaerobic conditions during the interaction with peroxidase. We discuss the contribution of peroxidases in the formation of gastrointestinal mucosal lesions induced by NSAIDs.

[Effect of task demand on the allocation of attention in a large three-dimensional space].

This study investigated the effect of task demand on the allocation of attention in a large three-dimensional (3-D) space. Two load conditions were conducted. In the low load condition, the observer was required to judge whether a target appeared nearer or further than the fixation point. In the high load condition, the observer was also required to judge whether the target appeared at the same position as the fixation point. Pre-cues, which indicated the spatial location of a target, were used in order to control attentional shifts in depth. There were three conditions about cue validity: valid, invalid and neutral conditions. The results indicated that the effect of cue validity was more significant in the high load condition. Furthermore, the attentional effect (the difference between invalid and valid conditions) changed with regard to the target position in the high load condition, but remained unchanged in the low load condition. This suggests that attentional allocation can be changed depending on the task demand in a large 3-D space.

Simulation Study of the Effect of the Side-Chain Structure on the Initial Nucleation Process of Polythiophene Derivatives.

We have investigated the initial nucleation process of polythiophene derivatives by molecular dynamics simulations to elucidate the role of flexible side chains in the crystallization process. We considered poly(3-hexylthiophene) (P3HT), poly(3,3‴-dihexylquarterthiophene) (PQT6), poly(3-dodecylthiophene) (P3DDT), and poly(3,3‴-didodecylquaterthiophene) (PQT12), in which the lengths and densities of the alkyl side chains are different. In the case of the short side-chain molecules (P3HT and PQT6), the initial nucleation process is based on the following steps. At the beginning, the thiophene rings align and ordering of the main chains commences shortly afterward. Ordering of the flexible side chains is induced after formation of a stacked structure of rigid main chains. In the case of a long and dense side-chain molecule (P3DDT), the initial nucleation process shows different features. The ordering process of the thiophene rings or main chains becomes very slow, while that of side chains becomes fast. In addition, the local order of the main chains becomes lower than those of P3HT and PQT6. These simulation results reveal that long and dense side chains suppress the nucleation process, whereas long but low-density side chains lead to formation of stacked nuclei in a different manner from those observed for short side-chain molecules.

Elevated levels of circulating cell-free DNA in the blood of patients with hepatitis C virus-associated hepatocellular carcinoma.

BACKGROUND: Circulating cell-free DNA is present in increased amounts in the blood of patients with one of several forms of cancer. MATERIALS AND METHODS: A real-time PCR assay with glutathione S-transferase pi (GSTP1) gene was used to measure cell-free DNA levels in the sera of 52 patients with hepatocellular carcinoma (HCC) associated with hepatitis C virus (HCV), which included 30 HCV carriers without known HCC and 16 HCV-negative non-cancer patients (controls). RESULTS: Cell-free DNA levels were significantly higher in the sera from HCC patients than in the sera from HCV carriers or the control subjects. Cell-free DNA levels were associated with the degree of tumor differentiation and size but not patient age, gender, TNM stage or levels of alpha-fetoprotein (AFP) or protein induced by vitamin K absence (PIVKA-II). The cell-free DNA assay had a sensitivity of 69.2% and a specificity of 93.3% in discriminating HCC and HCV carriers at the optimal cut-off value of 73.0 ng/ml, with an area of 0.90 (95% CI, 0.83-0.96) under the receiver operating characteristic curve. The discriminative power of cell-free DNA was superior to that of AFP or PIVKA-II. CONCLUSION: Our results showed that levels of circulating cell-free DNA are significantly increased in sera of patients with HCV-associated HCC, suggesting that circulating cell-free DNA may be a good biomarker specific for HCV-associated HCC.

Inactivation of alpha1-antiproteinase induced by phenylbutazone: participation of peroxyl radicals and hydroperoxide.

To clarify the action of a side-effect of phenylbutazone, we investigated the inactivation of alpha(1)-antiproteinase induced by phenylbutazone in the presence of horseradish peroxidase (HRP) and H(2)O(2) (HRP-H(2)O(2)). The activity of alpha(1)-antiproteinase was rapidly lost during the interaction of phenylbutazone with HRP-H(2)O(2) under aerobic conditions. Phenylbutazone showed a marked spectral change under aerobic conditions but not under anaerobic conditions. Spin trap agents were very effective in inhibiting alpha(1)-antiproteinase inactivation induced by phenylbutazone. Oxidation of phenylbutazone was stopped by catalase, but the inactivation reaction of alpha(1)-antiproteinase proceeded even after removal of H(2)O(2) in the reaction mixture. Formation of the peroxidative product from phenylbutazone was detected by iodometric assay. These results indicate that both peroxyl radicals and the peroxidative product of phenylbutazone participated in the inactivation of alpha(1)-antiproteinase. Other anti-inflammatory drugs did not inactivate alpha(1)-antiproteinase during interaction with HRP-H(2)O(2). Inactivation of alpha(1)-antiproteinase may contribute to serious side effects of phenylbutazone.