Near-nadir observations by the Multispectral Instrument (MSI) onboard the Sentinel-2 and the Operational Land Imager (OLI) onboard Landsat 8 were collected during two Simultaneous Nadir Overpasses (SNO). Multispectral...Near-nadir observations by the Multispectral Instrument (MSI) onboard the Sentinel-2 and the Operational Land Imager (OLI) onboard Landsat 8 were collected during two Simultaneous Nadir Overpasses (SNO). Multispectral images with 10, 20, and 30 m resolution from a spatially uniform area in the Saharan desert were acquired for direct comparison of MSI and OLI Top- Of-Atmosphere (TOA) reflectances. This paper presents an initial radiometric cross-calibration of the 8 corresponding spectral bands of the Sentinel-2 MSI and Landsat 8 OLI sensors. With the well-calibrated Landsat 8 OLI as a reference, the comparison indicates that 6 MSI bands are consistent with OLI within 3% in terms of spectral band adjustment factors Bi . The Near-Infra-Red (NIR) and cirrus bands are exceptions. They yield radiometric differences on the order of 8% and 15% respectively. Cross-calibration results show that the radiometric difference of the 7 corresponding bands are consistent to OLI within 1% or better, except on cirrus band. A pixel-by-pixel match between the MSI and OLI observations for different land covers showed that. This initial study suggests that the red-edge band B8A of MSI can be used to replace the NIR band B08 when conducting vegetation monitoring.展开更多
BACKGROUND:Human CD8 + CD28 - T-suppressor(Ts) cells have been considered to indicate a reduced need for immunosuppression in pediatric liver-intestine transplant recipients and recipients of deceased heart-kidney tra...BACKGROUND:Human CD8 + CD28 - T-suppressor(Ts) cells have been considered to indicate a reduced need for immunosuppression in pediatric liver-intestine transplant recipients and recipients of deceased heart-kidney transplants.However,in adult-to-adult living donor liver transplantation(A-A LDLT)little information is available and the clinical significance is still unknown. METHODS:Flow cytometry was used to detect the population of CD8+CD28 -Ts cells present in peripheral blood in A-A LDLT recipients(n=31),patients with end- stage liver disease(n=24)and healthy controls(n=19). Meanwhile,we tested the graft function and trough levels of immunosuppression in recipients.The clinical and follow- up data of 31 transplant recipients were analyzed. RESULTS:Compared with diseased controls(P=0.007) and healthy individuals(P=0.000),a notable expansion of CD8 + CD28 - Ts cells was found in recipients of A-A LDLT.This was associated with graft function,levels of immunosuppression and rejection episodes. CONCLUSIONS:To monitor the CD8 + CD28 - Ts cells levels is important to evaluate the immune state of recipients. Meanwhile,it is also important to promote expansion of CD8+CD28 -Ts cells in recipients of A-A LDLT,not only to sustain good graft function and decrease the dosage of immunosuppressants,but also to reduce the occurrence of rejection.展开更多
AIM:To determine the changes of CD8+ T subsets especially CD8+CD28-T regulatory cells in rat model of experimental colitis induced by 2,4-dinitrofluorobenzene (DNFB). METHODS:The rat model of experimental colitis was ...AIM:To determine the changes of CD8+ T subsets especially CD8+CD28-T regulatory cells in rat model of experimental colitis induced by 2,4-dinitrofluorobenzene (DNFB). METHODS:The rat model of experimental colitis was induced by enema with DNFB.Ten days later,colonic intraepithelial and splenic lymphooltes were isolated from colitis animals (n=16) and controls (n=8).The proportion of CD8+ T cells,CD8+CD28+ T cells and CD8+CD28-T regulatory cells were determined by flow cytometry. RESULTS:The model of experimental colitis was successfully established by DNFB that was demonstrated by bloody diarrhea,weight loss and colonic histopathology.The proportion of CD8+ T cells in either splenic or colonic intraepithelial lymphocytes was not significantly different between colitis animals and controls (spleen:34.6±7.24 % vs 33.5±9.41%, colon:14.0±8.93 % vs 18.0±4.06 %,P>0.05).But CD8+CD28- T regulatory cells from colitis animals were significantly more than those from controls (spleen:11.3±2.26 % vs 5.64±1.01%, colon:6.50±5.37 % vs 1.07±0.65 %,P<0.05).In contrast, CD8+CD28+ T cells from colitis animals were less than those from controls (spleen:23.3±6.14 % vs 27.8±9.70 %,P=0.06; colon:7.52±4.18 % vs 16.9±4.07 %,P<0.05).The proportion of CD8+CD28-T regulatory cells in splenic and colon intraepithelial CD8+ T cells from colitis animals was higher than that from controls (spleen:33.3±5.49 % vs 18.4±7.26 %, colon:46.0±14.3 % vs6.10±3.72 %,P<0.005). CONCLUSION:Experimental colitis of rats can be induced by DNFB with simplicity and good reproducibility.The proportion of CD8+CD28-T regulatory cells in rats with experimental colitis is increased,which may be associated with the pathogenesis of colitis.展开更多
Colon cancer is still one of the leading causes of cancer death worldwide. Although the host immune system has been shown to react against tumor cells, mainly through tumor infi ltrating lymphocytes and NK cells, tumo...Colon cancer is still one of the leading causes of cancer death worldwide. Although the host immune system has been shown to react against tumor cells, mainly through tumor infi ltrating lymphocytes and NK cells, tumor cells may utilize different ways to escape anti-tumor immune response. Tumor infi ltration of CD8+ and CD4+ (T-bet+) effector T cells has been attributed to a beneficial outcome, and the enhancement of T cell activation through T cell receptor stimulation and co-stimulatory signals provides promising strategies for immunotherapy of colon cancer. Growing evidence supports a role for the Fas/FasL system in tumor immunology, although the mechanisms and consequences of FasL activation in colon cancer are not completely understood. In animal models, depletion of regulatory T cells (CD4+ CD25+ T cells) can enhance the anti-tumor immune response under certain conditions. Taken together, recent insights in the immune reaction against colon carcinoma have provided new approaches to immunotherapy, although much remains to be learned about the exact mechanisms.展开更多
文摘Near-nadir observations by the Multispectral Instrument (MSI) onboard the Sentinel-2 and the Operational Land Imager (OLI) onboard Landsat 8 were collected during two Simultaneous Nadir Overpasses (SNO). Multispectral images with 10, 20, and 30 m resolution from a spatially uniform area in the Saharan desert were acquired for direct comparison of MSI and OLI Top- Of-Atmosphere (TOA) reflectances. This paper presents an initial radiometric cross-calibration of the 8 corresponding spectral bands of the Sentinel-2 MSI and Landsat 8 OLI sensors. With the well-calibrated Landsat 8 OLI as a reference, the comparison indicates that 6 MSI bands are consistent with OLI within 3% in terms of spectral band adjustment factors Bi . The Near-Infra-Red (NIR) and cirrus bands are exceptions. They yield radiometric differences on the order of 8% and 15% respectively. Cross-calibration results show that the radiometric difference of the 7 corresponding bands are consistent to OLI within 1% or better, except on cirrus band. A pixel-by-pixel match between the MSI and OLI observations for different land covers showed that. This initial study suggests that the red-edge band B8A of MSI can be used to replace the NIR band B08 when conducting vegetation monitoring.
基金supported by grants from the National Natural Science Foundation of China(No.30772124)the Doctoral Fund of the Ministry of Education of China(No.20070610147).
文摘BACKGROUND:Human CD8 + CD28 - T-suppressor(Ts) cells have been considered to indicate a reduced need for immunosuppression in pediatric liver-intestine transplant recipients and recipients of deceased heart-kidney transplants.However,in adult-to-adult living donor liver transplantation(A-A LDLT)little information is available and the clinical significance is still unknown. METHODS:Flow cytometry was used to detect the population of CD8+CD28 -Ts cells present in peripheral blood in A-A LDLT recipients(n=31),patients with end- stage liver disease(n=24)and healthy controls(n=19). Meanwhile,we tested the graft function and trough levels of immunosuppression in recipients.The clinical and follow- up data of 31 transplant recipients were analyzed. RESULTS:Compared with diseased controls(P=0.007) and healthy individuals(P=0.000),a notable expansion of CD8 + CD28 - Ts cells was found in recipients of A-A LDLT.This was associated with graft function,levels of immunosuppression and rejection episodes. CONCLUSIONS:To monitor the CD8 + CD28 - Ts cells levels is important to evaluate the immune state of recipients. Meanwhile,it is also important to promote expansion of CD8+CD28 -Ts cells in recipients of A-A LDLT,not only to sustain good graft function and decrease the dosage of immunosuppressants,but also to reduce the occurrence of rejection.
基金the National Natural Science Foundation of China,No.30240051
文摘AIM:To determine the changes of CD8+ T subsets especially CD8+CD28-T regulatory cells in rat model of experimental colitis induced by 2,4-dinitrofluorobenzene (DNFB). METHODS:The rat model of experimental colitis was induced by enema with DNFB.Ten days later,colonic intraepithelial and splenic lymphooltes were isolated from colitis animals (n=16) and controls (n=8).The proportion of CD8+ T cells,CD8+CD28+ T cells and CD8+CD28-T regulatory cells were determined by flow cytometry. RESULTS:The model of experimental colitis was successfully established by DNFB that was demonstrated by bloody diarrhea,weight loss and colonic histopathology.The proportion of CD8+ T cells in either splenic or colonic intraepithelial lymphocytes was not significantly different between colitis animals and controls (spleen:34.6±7.24 % vs 33.5±9.41%, colon:14.0±8.93 % vs 18.0±4.06 %,P>0.05).But CD8+CD28- T regulatory cells from colitis animals were significantly more than those from controls (spleen:11.3±2.26 % vs 5.64±1.01%, colon:6.50±5.37 % vs 1.07±0.65 %,P<0.05).In contrast, CD8+CD28+ T cells from colitis animals were less than those from controls (spleen:23.3±6.14 % vs 27.8±9.70 %,P=0.06; colon:7.52±4.18 % vs 16.9±4.07 %,P<0.05).The proportion of CD8+CD28-T regulatory cells in splenic and colon intraepithelial CD8+ T cells from colitis animals was higher than that from controls (spleen:33.3±5.49 % vs 18.4±7.26 %, colon:46.0±14.3 % vs6.10±3.72 %,P<0.005). CONCLUSION:Experimental colitis of rats can be induced by DNFB with simplicity and good reproducibility.The proportion of CD8+CD28-T regulatory cells in rats with experimental colitis is increased,which may be associated with the pathogenesis of colitis.
文摘Colon cancer is still one of the leading causes of cancer death worldwide. Although the host immune system has been shown to react against tumor cells, mainly through tumor infi ltrating lymphocytes and NK cells, tumor cells may utilize different ways to escape anti-tumor immune response. Tumor infi ltration of CD8+ and CD4+ (T-bet+) effector T cells has been attributed to a beneficial outcome, and the enhancement of T cell activation through T cell receptor stimulation and co-stimulatory signals provides promising strategies for immunotherapy of colon cancer. Growing evidence supports a role for the Fas/FasL system in tumor immunology, although the mechanisms and consequences of FasL activation in colon cancer are not completely understood. In animal models, depletion of regulatory T cells (CD4+ CD25+ T cells) can enhance the anti-tumor immune response under certain conditions. Taken together, recent insights in the immune reaction against colon carcinoma have provided new approaches to immunotherapy, although much remains to be learned about the exact mechanisms.
