Human dental pulp stem/progenitor cells (hDPSCs) are attractive candidates for regenerative therapy because they can be easily expanded to generate colony-forming unit–fibroblasts (CFU-Fs) on plastic ...and the large cell numbers required for transplantation. However, isolation based on adherence to plastic inevitably changes the surface marker expression and biological properties of the cells. Consequently, little is currently known about the original phenotypes of tissue precursor cells that give rise to plastic-adherent CFU-Fs. To better understand the in vivo functions and translational therapeutic potential of hDPSCs and other stem cells, selective cell markers must be identified in the progenitor cells. Here, we identified a dental pulp tissue–specific cell population based on the expression profiles of 2 cell-surface markers LNGFR (CD271) and THY-1 (CD90). Prospectively isolated, dental pulp–derived LNGFRLow+THY-1High+ cells represent a highly enriched population of clonogenic cells—notably, the isolated cells exhibited long-term proliferation and multilineage differentiation potential in vitro. The cells also expressed known mesenchymal cell markers and promoted new bone formation to heal critical-size calvarial defects in vivo. These findings suggest that LNGFRLow+THY-1High+ dental pulp–derived cells provide an excellent source of material for bone regenerative strategies.
The effects of thermal aging of stainless steel weld-overlay claddings of nuclear reactor pressure vessels on the microstructure and hardness of the claddings were investigated using atom probe ...tomography and nanoindentation testing. The claddings were aged at 400°C for periods of 100–10,000h. The fluctuation in Cr concentration in the δ-ferrite phase, which was caused by spinodal decomposition, progressed rapidly after aging for 100h, and gradually for aging durations greater than 1000h. On the other hand, NiSiMn clusters, initially formed after aging for less than 1000h, had the highest number density after aging for 2000h, and coarsened after aging for 10,000h. The hardness of the δ-ferrite phase also increased rapidly for short period of aging, and saturated after aging for longer than 1000h. This trend was similar to the observed Cr fluctuation concentration, but different from the trend seen in the formation of the NiSiMn clusters. These results strongly suggest that the primary factor responsible for the hardening of the δ-ferrite phase owing to thermal aging is Cr spinodal decomposition.
► Microstructural changes in stainless steel electroslag weld-overlay cladding. ► Thermal aging caused progress of spinodal decomposition and precipitation of G phases in the δ-ferrite phase. ► The ...degree of the spinodal decomposition had a linear relationship to the hardness.
The effect of thermal aging on microstructural changes was investigated in stainless steel weld-overlay cladding composed of 90% austenite and 10% δ-ferrite phases using atom probe tomography (APT). In as-received materials subjected to cooling process after post-welding heat treatments (PWHT), a slight fluctuation of the Cr concentration was already observed due to spinodal decomposition in the ferrite phase but not in the austenitic phase. Thermal aging at 400
°C for 10,000
h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn
=
16:7:6 in the ferrite phase. The chemical compositions of M
23C
6 type carbides seemed to be formed at the austenite/ferrite interface were analyzed. The analyses of the magnitude of the spinodal decomposition and the hardness implied that the spinodal decomposition was the main cause of the hardening.
The effect of thermal aging on microstructural changes in stainless steel submerged arc weld-overlay cladding of reactor pressure vessels was investigated using atom probe tomography (APT). In ...as-received materials subjected to post-welding heat treatments (PWHTs), with a subsequent furnace cooling, a slight fluctuation of the Cr concentration was observed due to spinodal decomposition in the δ-ferrite phase but not in the austenitic phase. Thermal aging at 400°C for 10,000h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn=16:7:6 in the δ-ferrite phase. The degree of the spinodal decomposition in the submerged arc weld sample was similar to that in the electroslag weld one reported previously. We also observed a carbide on the γ-austenite and δ-ferrite interface. There were no Cr depleted zones around the carbide.
The correlation of microstructure evolution and hardening was studied in two kinds of A533B-1 steel with high and low levels of Cu irradiated in a range of dose from 0.32 to 9.9
×
10
19
n
cm
−2 (
E
>
...1
MeV) under a high flux of about 1.7
×
10
13
n
cm
−2
s
−1 using three-dimensional local electrode atom probe (3DAP), positron annihilation (PA) techniques, and Vickers microhardness. The early rapid hardening was found to be caused by mainly matrix defects such as mono- or di-vacancies (
V
1
−
V
2) and/or dislocations indicated by the PA analysis. The 3DAP analysis showed that dense dispersion of dilute Cu rich clusters and lean distribution of Mn–Ni–Si rich clusters, which
were
identified to possess the same dislocation-pinning effect
by applying a Russell and Brown model,
were responsible for large and small hardening in high- and low-Cu steels irradiated above 0.59
×
10
19
n
cm
2, respectively.
The microstructures and the hardness of stainless steel weld overlay cladding of reactor pressure vessels subjected to neutron irradiation at a dose of 7.2×1019ncm−2 (E>1MeV) and a flux of ...1.1×1013ncm−2s−1 at 290°C were investigated by atom probe tomography and by a nanoindentation technique. To isolate the effects of the neutron irradiation, we compared the results of the measurements of the neutron-irradiated samples with those from a sample aged at 300°C for a duration equivalent to that of the irradiation. The Cr concentration fluctuation was enhanced in the δ-ferrite phase of the irradiated sample. In addition, enhancement of the concentration fluctuation of Si, which was not observed in the aged sample, was observed. The hardening in the δ-ferrite phase occurred due to both irradiation and aging; however, the hardening of the irradiated sample was more than that expected from the Cr concentration fluctuation, which suggested that the Si concentration fluctuation and irradiation-induced defects were possible origins of the additional hardening.
Microstructural changes in the stainless steel weld overlay cladding of reactor pressure vessels subjected to neutron irradiation with a fluence of 7.2×1023nm−2 (E>1MeV) and a flux of 1.1×1017nm−2 ...s−1 at 290°C were investigated by atom probe tomography. The results showed a difference in the microstructural changes that result from neutron irradiation and thermal aging. Neutron irradiation resulted in the slight progression of Cr spinodal decomposition and an increase in the fluctuation of the Si, Ni, and Mn concentrations in the ferrite phases, with formation of γ′-like clusters in the austenite phases. On the other hand, thermal aging resulted in the considerable progression of the Cr spinodal decomposition, formation of G-phases, and a decrease in the Si and an increase in the Ni and Mn concentration fluctuations at the matrix in the ferrite phases, without the microstructural changes in the austenite phases.
Oral mucositis (OM) is a frequent adverse effect of allogenic or autologous hematopoietic SCT. It results from direct toxic injury to the mucosal epithelial cells by the immunosuppressive regimen. ...Here, we compared the incidence and severity of OM between a group of 24 patients who received proper oral management during hematopoietic SCT and a group of 24 who did not. The oral management group received pre-hematopoietic SCT instruction on oral care and an oral examination in the clean room. Differences in the incidence and severity of OM between the two groups were examined statistically. OM was observed in 14 (58.3%) patients in the oral management group and 22 (91.6%) in the control group. The median of the OM score was 1 for the oral management group (range 0 to 3) and 2 for the control group (range 0 to 3). There was a significant difference in the OM score (P<0.05) and in the incidence of OM between the two groups (P<0.01). This study shows that oral management may decrease the occurrence of OM. Our results also suggest that it is important to include an oral management provider on the hematopoietic SCT team.
Pre-hematopoietic stem cell transplantation (HSCT) dental treatment is essential to prevent serious infections from oral sources during immunosuppression, in patients who undergo HSCT therapy. This ...study was planned to establish a dental management protocol for such patients. Forty-one patients scheduled for HSCT to treat hematological malignancies were consecutively enrolled in the prospective trial. The dental status of all patients was evaluated by clinical and radiographic examination at a median of 47 days before the commencement of HSCT therapy. Thirty-six patients had one or more dental diseases; the remaining five had none. Caries was found in 26 patients, apical periodontitis in 19, marginal periodontitis in 24 and a partially erupted third molar in 11. Our policy is to preserve patients' teeth whenever possible, and therefore minimal dental intervention was planned. Treatment was completed for all 36 patients with dental pathologies, before the conditioning regimen began. All patients received the scheduled HSCT therapy without alteration, interruption or delay, and did not show any signs or symptoms associated with odontogenic infection while they were immunosuppressed. This protocol, therefore, appears to be appropriate for the pre-HSCT dental treatment of patients with hematological diseases.
Diacylglycerol (DG) comprises up to approximately 10% of various edible oils. In the present study, we examined the effects of dietary DG consisting mainly of 1,3-species on body weight, body fat ...accumulation, and mRNA levels of various genes involved in energy homeostasis in obesity-prone C57BL/6J mice. Five-month feeding with the high triacylglycerol (TG) diet (30% TG + 13% sucrose) resulted in significant increases in body weight, visceral fat accumulation, and circulating insulin and leptin levels compared with mice fed the control diet (5% TG). Compared with mice fed the high TG diet, body weight gain and visceral fat weight were reduced by 70% and 79%, respectively, in those fed the high DG diet (30% DG + 13% sucrose). In addition, circulating leptin and insulin levels were reduced to the respective control levels. Compared with high TG feeding, high DG feeding suppressed the elevation of leptin mRNA expression in adipose tissue, and up-regulated acyl-coenzyme (Co)A oxidase and acyl-CoA synthase mRNA expression in the liver. These results indicate that dietary DG is beneficial for suppression of high fat diet-induced body fat accumulation. Furthermore, it is suggested that structural differences in DG and TG, but not the composition of fatty acid, markedly affect nutritional behavior of lipids. -- Murase, T., T. Mizuno, T. Omachi, K. Onizawa, Y. Komine, H. Kondo, T. Hase, and I. Tokimitsu. Dietary diacylglycerol suppresses high fat and high sucrose diet-induced body fat accumulation in C57BL/6J mice. J. Lipid Res. 2001. 42: 372--378.
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