Alloreactive T Cells to Identify Risk HLA Alleles for Retransplantation After Acute Accelerated Steroid-Resistant Rejection.

The risk of rejection by cellular alloreactivity to the transplant donor is not routinely assessed. Here we analyzed alloreactive T cells in kidney transplant recipients and report how their detection may have helped to prevent rejection of a second kidney graft in a patient with a history of acute accelerated steroid-resistant nonhumoral rejection. Alloreactive CD4 and CD8 T cells were quantified using a flow-cytometric mixed lymphocyte reaction assay based on interferon-γ induction. A group of 16 nonrejecting transplant recipients did not show any alloreactive T-cell immunity to their respective donors, whereas alloreactivity to third-party controls was detectable. In the patient with rejection, HLA-specific antibodies were not detectable before and shortly after rejection, but after transplantation the patient showed exceptionally high frequencies of alloreactive T cells against 2 of 11 HLA-typed controls (0.604% and 0.791% alloreactive CD4 T cells and 0.792% and 0.978% alloreactive CD8 T cells) who shared HLA alleles (HLA-A*24, -B*44, -C*02, -DQB1*5) with the kidney donor. These HLA alleles were subsequently excluded for allocation of a second graft. No alloreactive T cells were observed toward the second kidney donor, and this transplantation was performed successfully. Thus, shared HLA alleles between the donor and third-party controls may suggest that alloreactive T cells had contributed to rejection of the first graft. The rejecting patient highlights that determination of cellular alloreactivity before transplantation may be applied to identify unacceptable mismatches and to reduce the risk for acute cellular rejection episodes.

The development, validation and application of a finite element upper extremity model subjected to air bag loading.

Both frontal and side air bags can inflict injuries to the upper extremities in cases where the limb is close to the air bag module at the time of impact. Current dummy limbs show qualitatively correct kinematics under air bag loading, but they lack biofidelity in long bone bending and fracture. Thus, an effective research tool is needed to investigate the injury mechanisms involved in air bag loading and to judge the improvements of new air bag designs. The objective of this study is to create an efficient numerical model that exhibits both correct global kinematics as well as localized tissue deformation and initiation of fracture under various impact conditions. The development of the model includes the creation of a sufficiently accurate finite element mesh, the adaptation of material properties from literature into constitutive models and the definition of kinematic constraints at articular joint locations. In order to make the model applicable for full-scale simulations, it was coupled with a computationally efficient human model. The model was validated against available cadaver experiments, including static and dynamic three-point-bending tests to the arm and forearm, as well as frontal air bag to forearm impact tests. The sensitivity of the model to changes in air bag properties and upper limb orientation are demonstrated by performing parametric studies. It is shown that the risk of forearm fracture increases substantially with proximity to the deploying frontal air bag and air bag aggressiveness, which corresponds to experimental findings. However, it is shown that increasing the forearm supination angle is protective for the occurrence of forearm fracture. In conclusion, the developed model proves to be a useful research tool to investigate trends in injury severity as a result of a changing frontal air bag to upper extremity loading environment.

The U.S. decennial census: an agenda for change.

"The results and experiences of the 1990 [U.S.] census demonstrate that the American population has grown too diverse and dynamic to be accurately counted solely by the traditional 'headcount' approach, and that fundamental changes must be implemented for a successful census in 2000. In the past, each census was more accurate than the preceding one, in part because of increased spending. However, the accuracy of the 1990 census fell below that of the 1980 census, as census costs escalated significantly. The $2.6 billion the nation spent on the 1990 census represented a 65 percent increase in constant dollars over the cost of the 1980 census. Additional cost escalation with the 2000 census is probable unless needed reforms are implemented. Although it is too early to identify the precise design needed for a more cost-effective census in 2000, the General Accounting Office believes that a number of opportunities for reform are worthy of aggressive attention."