The importance of size-exclusion characteristics of type I collagen in bonding to dentin matrices

The mineral phase of dentin is located primarily within collagen fibrils. During development, bone or dentin collagen fibrils are formed first and then water within the fibril is replaced with apatite crystallites. Mineralized collagen contains very little water. During dentin bonding, acid-etching of mineralized dentin solubilizes the mineral crystallites and replaces them with water. During the infiltration phase of dentin bonding, adhesive comonomers are supposed to replace all of the collagen water with adhesive monomers that are then polymerized into copolymers. The authors of a recently published review suggested that dental monomers were too large to enter and displace water from collagen fibrils. If that were true, the endogenous proteases bound to dentin collagen could be responsible for unimpeded collagen degradation that is responsible for the poor durability of resin-dentin bonds. The current work studied the size-exclusion characteristics of dentin collagen, using a gel-filtration-like column chromatography technique, using dentin powder instead of Sephadex. The elution volumes of test molecules, including adhesive monomers, revealed that adhesive monomers smaller than ∼1000 Da can freely diffuse into collagen water, while molecules of 10,000 Da begin to be excluded, and bovine serum albumin (66,000 Da) was fully excluded. These results validate the concept that dental monomers can permeate between collagen molecules during infiltration by etch-and-rinse adhesives in water-saturated matrices.

Note: Development of a high resolution and wide band terahertz spectrometer based on a 1 μm-band external cavity diode laser

We have developed a frequency-domain terahertz spectrometer based on homebuilt 1 μm band external cavity diode lasers, for high resolution spectroscopy. Our spectrometer is digitally controlled to a resolution of 10 MHz, and uses InGaAs/GaAs photoconductive antennas. We have obtained a spectrum in the range 0.02 THz to 2.5 THz, which exceeds the conventional temperature tuning range of a distributed feedback diode laser. We achieved a signal-to-noise ratio of up to 80 dB at around 0.05 THz, and 20 dB at around 2.0 THz. We observed water vapor spectra in the atmosphere with a frequency step of 0.6 GHz in the region between 1.0 THz and 2.0 THz. We have demonstrated that our 1 μm-band frequency-domain terahertz spectrometer is competitive when compared with existing 800 nm- and 1.5 μm-band systems.

Universality of the dispersive spin-resonance mode in superconducting BaFe2As2

Spin fluctuations in superconducting BaFe2(As(1-x)P(x))2 (x=0.34, T(c)=29.5 K) are studied using inelastic neutron scattering. Well-defined commensurate magnetic signals are observed at (π, 0), which is consistent with the nesting vector of the Fermi surface. Antiferromagnetic (AFM) spin fluctuations in the normal state exhibit a three-dimensional character reminiscent of the AFM order in nondoped BaFe2As2. A clear spin gap is observed in the superconducting phase forming a peak whose energy is significantly dispersed along the c axis. The bandwidth of dispersion becomes larger with approaching the AFM ordered phase universally in all superconducting BaFe2As2, indicating that the dispersive feature is attributed to three-dimensional AFM correlations. The results suggest a strong relationship between the magnetism and superconductivity.

Anisotropy of the in-plane resistivity of underdoped Ba(Fe(1-x)Co(x))2As2 superconductors induced by impurity scattering in the antiferromagnetic orthorhombic phase

We investigated the in-plane resistivity anisotropy for underdoped Ba(Fe(1-x)Co(x))(2)As(2) single crystals with improved quality. We demonstrate that the anisotropy in resistivity in the magnetostructural ordered phase arises from the anisotropy in the residual component which increases in proportion to the Co concentration x. This gives evidence that the anisotropy originates from the impurity scattering by Co atoms substituted for the Fe sites, rather than the so far proposed mechanisms such as the anisotropy of Fermi velocities of reconstructed Fermi surface pockets. As doping proceeds to the paramagnetic-tetragonal phase, a Co impurity transforms to a weak and isotropic scattering center.

Effect of solvent evaporation strategies on regional bond strength of one-step self-etch adhesives to root canal dentine

AIM

To evaluate the efficacy of different solvent evaporation strategies on bonding of one-step self-etch adhesives to root canal dentine.

METHODOLOGY

Two dual-cure resin core systems (Clearfil DC Bond/Clearfil DC Core Automix and Clearfil Tri-S Bond Plus/Clearfil DC Core Plus; Kuraray Noritake Dental, Tokyo, Japan) were equally applied in 24 post spaces from extracted human mandibular premolars. After the adhesive application, specimens were randomly assigned into four water/solvent evaporation strategies as follows (I) insertion of absorbent paper point for 10 s: P, (II) 10 s air-blowing: A, (III) as (II) followed by insertion of absorbent paper point: AP, (IV) as (III) followed by 10 s additional air-blowing: APA. Then, the adhesives were light cured, and resin core materials were placed into the post space, followed by light curing for 60 s. After water storage for 24 h, 0.6 × 0.6 mm-thick beams were prepared to measure the regional μTBS. The mode of failure was also observed. The μTBS values were statistically analysed using three-way anova and Duncan HSD test (α = 0.05).

RESULTS

In the coronal region, there were no significant differences in μTBS between each evaporation strategy (P > 0.05), except P group. However, in the apical region, APA and AP groups significantly increased in μTBS compared with A and P groups (P < 0.05). Only in the APA group of Clearfil Tri-S Bond Plus/Clearfil DC Core Plus, was there no significant difference in μTBS between the coronal and apical regions (P > 0.05).

CONCLUSION

The use of paper points with additional air-blowing for removing excessive adhesive and evaporating residual water/solvent would be effective in producing higher bond strength for the tested one-step self-etch adhesives and fewer blister formations in deeper regions of the post space.

Dependence of carrier doping on the impurity potential in transition-metal-substituted FeAs-based superconductors

In order to examine to what extent the rigid-band-like electron doping scenario is applicable to the transition metal-substituted Fe-based superconductors, we have performed angle-resolved photoemission spectroscopy studies of Ba(Fe(1-x)Ni(x))(2)As(2) (Ni-122) and Ba(Fe(1-x)Cu(x))(2)As(2) (Cu-122), and compared the results with Ba(Fe(1-x)Co(x))(2)As(2) (Co-122). We find that Ni 3d-derived features are formed below the Fe 3d band and that Cu 3d-derived ones further below it. The electron and hole Fermi surface (FS) volumes are found to increase and decrease with substitution, respectively, qualitatively consistent with the rigid-band model. However, the total extra electron number estimated from the FS volumes (the total electron FS volume minus the total hole FS volume) is found to decrease in going from Co-, Ni-, to Cu-122 for a fixed nominal extra electron number, that is, the number of electrons that participate in the formation of FS decreases with increasing impurity potential. We find that the Néel temperature T(N) and the critical temperature T(c) maximum are determined by the FS volumes rather than the nominal extra electron concentration or the substituted atom concentration.

Decreased immunoglobulin A concentrations in feces, duodenum, and peripheral blood mononuclear cells of dogs with inflammatory bowel disease

BACKGROUND

Although immunoglobulin A (IgA) plays a key role in regulating gut homeostasis, its role in canine inflammatory bowel disease (IBD) is unknown.

HYPOTHESIS

IgA expression may be altered in dogs with IBD, unlike that observed in healthy dogs and dogs with other gastrointestinal diseases.

ANIMALS

Thirty-seven dogs with IBD, 10 dogs with intestinal lymphoma, and 20 healthy dogs.

METHODS

Prospective study. IgA and IgG concentrations in serum, feces, and duodenal samples were measured by ELISA. IgA(+) cells in duodenal lamina propria and IgA(+) CD21(+) peripheral blood mononuclear cells (PBMCs) were examined by immunohistochemistry and flow cytometry, respectively. Duodenal expression of the IgA-inducing cytokine transforming growth factor β (TGF-β), B cell activating factor (BAFF), and a proliferation-inducing ligand (APRIL) was quantified by real-time RT-PCR.

RESULTS

Compared to healthy dogs, dogs with IBD had significantly decreased concentrations of IgA in fecal and duodenal samples. The number of IgA(+) CD21(+) PBMCs and IgA(+) cells in duodenal lamina propria was significantly lower in dogs with IBD than in healthy dogs or dogs with intestinal lymphoma. Duodenal BAFF and APRIL mRNA expression was significantly higher in IBD dogs than in the healthy controls. Duodenal TGF-β mRNA expression was significantly lower in dogs with IBD than in healthy dogs and dogs with intestinal lymphoma.

CONCLUSIONS AND CLINICAL IMPORTANCE

IBD dogs have decreased IgA concentrations in feces and duodenum and fewer IgA(+) PBMCs, which might contribute to development of chronic enteritis in dogs with IBD.

Effect of Co doping on the in-plane anisotropy in the optical spectrum of underdoped Ba(Fe(1-x)Co(x))2As2

We investigate the anisotropy in the in-plane optical spectra of detwinned Ba(Fe(1-x)Co(x))(2)As(2). The optical conductivity spectrum of BaFe(2)As(2) shows appreciable anisotropy in the magnetostructural ordered phase, whereas the dc (ω = 0) resistivity is nearly isotropic at low temperatures. Upon Co doping, the resistivity becomes highly anisotropic, while the finite-energy intrinsic anisotropy is suppressed. It is found that anisotropy in resistivity arises from anisotropic impurity scattering due to the presence of doped Co atoms, and it is extrinsic in origin. The intensity of a specific optical phonon mode is also found to show striking anisotropy in the ordered phase. The anisotropy induced by the Co impurity and that observed in the optical phonon mode are hallmarks of the highly polarizable electronic state in the ordered phase.

The importance of orthotopic implantation to the isolation and biological characterization of a metastatic human clear cell renal-carcinoma in nude-mice

We established a new human renal cell carcinoma system to study some properties of metastatic renal cancer cells and the influence of the organ environment on their metastatic potential. Renal cell carcinoma obtained from a surgical specimen was dissociated enzymatically. Cells were injected into the subcutis, kidney, cecal wall, and spleen of nude mice. Tumors grew in the subcutis and kidney. Only kidney tumors produced distant metastasis. Subcutaneous tumors were avascular and encapsulated, whereas kidney tumors were highly vascularized and invaded the kidney parenchyma. Cell lines were also established from several spontaneous lung metastases. The most metastatic cell line (LM-6) expressed higher levels of basic fibroblast growth factor, gelatinase, and urokinase activity. These results show that human neoplasms are heterogeneous for biologic properties, that orthotopic implantation is essential for the selection, growth, and metastasis of human renal cell carcinoma cells, and that metastatic cells must possess multiple properties to enable them to complete the process.