Allocation to highly sensitized patients based on acceptable mismatches results in low rejection rates comparable to nonsensitized patients

Contains fulltext : 208426.pdf (publisher's version ) (Open Access)Whereas regular allocation avoids unacceptable mismatches on the donor organ, allocation to highly sensitized patients within the Eurotransplant Acceptable Mismatch (AM) program is based on the patient's HLA phenotype plus acceptable antigens. These are HLA antigens to which the patient never made antibodies, as determined by extensive laboratory testing. AM patients have superior long-term graft survival compared with highly sensitized patients in regular allocation. Here, we questioned whether the AM program also results in lower rejection rates. From the PROCARE cohort, consisting of all Dutch kidney transplants in 1995-2005, we selected deceased donor single transplants with a minimum of 1 HLA mismatch and determined the cumulative 6-month rejection incidence for patients in AM or regular allocation. Additionally, we determined the effect of minimal matching criteria of 1 HLA-B plus 1 HLA-DR, or 2 HLA-DR antigens on rejection incidence. AM patients showed significantly lower rejection rates than highly immunized patients in regular allocation, comparable to nonsensitized patients, independent of other risk factors for rejection. In contrast to highly sensitized patients in regular allocation, minimal matching criteria did not affect rejection rates in AM patients. Allocation based on acceptable antigens leads to relatively low-risk transplants for highly sensitized patients with rejection rates similar to those of nonimmunized individuals

Allocation to highly sensitized patients based on acceptable mismatches results in low rejection rates comparable to nonsensitized patients

Whereas regular allocation avoids unacceptable mismatches on the donor organ, allocation to highly sensitized patients within the Eurotransplant Acceptable Mismatch (AM) program is based on the patient\'s HLA phenotype plus acceptable antigens. These are HLA antigens to which the patient never made antibodies, as determined by extensive laboratory testing. AM patients have superior long-term graft survival compared with highly sensitized patients in regular allocation. Here, we questioned whether the AM program also results in lower rejection rates. From the PROCARE cohort, consisting of all Dutch kidney transplants in 1995-2005, we selected deceased donor single transplants with a minimum of 1 HLA mismatch and determined the cumulative 6-month rejection incidence for patients in AM or regular allocation. Additionally, we determined the effect of minimal matching criteria of 1 HLA-B plus 1 HLA-DR, or 2 HLA-DR antigens on rejection incidence. AM patients showed significantly lower rejection rates than highly immunized patients in regular allocation, comparable to nonsensitized patients, independent of other risk factors for rejection. In contrast to highly sensitized patients in regular allocation, minimal matching criteria did not affect rejection rates in AM patients. Allocation based on acceptable antigens leads to relatively low-risk transplants for highly sensitized patients with rejection rates similar to those of nonimmunized individuals

Allocation to highly sensitized patients based on acceptable mismatches results in low rejection rates comparable to nonsensitized patients

Whereas regular allocation avoids unacceptable mismatches on the donor organ, allocation to highly sensitized patients within the Eurotransplant Acceptable Mismatch (AM) program is based on the patient's HLA phenotype plus acceptable antigens. These are HLA antigens to which the patient never made antibodies, as determined by extensive laboratory testing. AM patients have superior long-term graft survival compared with highly sensitized patients in regular allocation. Here, we questioned whether the AM program also results in lower rejection rates. From the PROCARE cohort, consisting of all Dutch kidney transplants in 1995-2005, we selected deceased donor single transplants with a minimum of 1 HLA mismatch and determined the cumulative 6-month rejection incidence for patients in AM or regular allocation. Additionally, we determined the effect of minimal matching criteria of 1 HLA-B plus 1 HLA-DR, or 2 HLA-DR antigens on rejection incidence. AM patients showed significantly lower rejection rates than highly immunized patients in regular allocation, comparable to nonsensitized patients, independent of other risk factors for rejection. In contrast to highly sensitized patients in regular allocation, minimal matching criteria did not affect rejection rates in AM patients. Allocation based on acceptable antigens leads to relatively low-risk transplants for highly sensitized patients with rejection rates similar to those of nonimmunized individuals

Estimation of areal soil water content through microwave remote sensing

In this thesis the use of microwave remote sensing to estimate soil water content is investigated. A general framework is described which is applicable to both passive and active microwave remote sensing of soil water content. The various steps necessary to estimate areal soil water content are discussed through literature review, laboratory experimental results and results of extensive field experimental work. Even with the large amount of field data being available, no experiment provided all the necessary data to illustrate the framework completely for both passive and active techniques.The framework developed is intended to be independent of the models used. In this way insight is gained in the dominating factors and problems associated with the use of remote sensing and not with specific models. Throughout the thesis both passive and active techniques are used and compared.The passive techniques, mainly L-band and C-band, show better results that are more easily obtained at the cost of a relatively low spatial resolution. The standard error in the remotely sensed soil moisture estimates (The active techniques are severely tampered by vegetation and surface roughness effects making soil water content estimation more cumbersome. Despite these drawbacks this technique is complimentary to the passive technique because of the higher attainable spatial resolutions and the possible use of longer wave lengths (P-band). The latter enables estimation of soil water content under vegetation cover and over larger depths, about 30 cm for P-band, compared to for example about 5-10 cm depth for L-band. The standard error of soil moisture estimates in absence of vegetation is in general around 5%.In this thesis the effects of vegetation have been excluded in the analysis. To operationalise remotely sensed soil moisture estimation it will be necessary to develop methods that can estimate soil water content when vegetation is present. Especially for active and space-borne passive techniques.Direct comparison between a passive L-band radiometer and an active C-band radar showed consistent results over stationary heterogeneous areas, i.e. low vegetation cover and relatively homogeneous surface roughness characteristics.The estimation of soil water content needs to be done from the perspective of the objective. This means that in the case of hydrological and meteorological modeling assimilation of direct remotely sensed measurements such as brightness temperatures or backscattering coefficients can yield better results, e.g. better forecast, than incorporation of the remotely sensed soil water content . This depends strongly on the land surface parameterization and in particular the definition of soil water content in the models used.</p