Pretransplant injection of allograft recipients with donor blood or lymphocytes permits allograft tolerance without the presence of persistent donor microchimerism

Donor-recipient microchimerism has recently been suggested to play a critical role in the induction and maintenance of allograft tolerance. In this study we sought evidence for this hypothesis using the LEW-to-ACI cardiac allograft as a model system. Donor-specific tolerance to cardiac allografts was induced by intravenous or intraportal injection of graft recipients with donor peripheral blood, T cells, or B cells 7 days before transplantation. All the graft recipients injected with donor antigens accepted donor heart grafts indefinitely when compared with control recipients that rejected donor allografts in 12 days. Long-term graft survivors rejected third-party BN heart allografts in 14 days without an adverse effect on the survival of the first LEW heart allografts, demonstrating the specificity of the tolerance. Tissue lysates prepared from heart, kidney, liver, bone marrow, thymus, lymph nodes, and spleen of tolerant (>120 days) graft recipients were analyzed for the presence of donor DNA using LEW T cell receptor C beta gene-specific primers for polymerase chain reaction that detects donor DNA at > or = 1:10,000 dilution. Donor DNA was detected in 77% of tolerant graft recipients. Chimeric recipients showed variations in the levels and presence of donor DNA in different tissues. The status of donor microchimerism, with respect to its presence and tissue distribution, was dependent upon the donor cell type and route of injection used for the induction of tolerance. Intraportal injection of the graft recipients with donor peripheral blood resulted in the highest degree of chimerism, whereas intravenous injection with donor B cells did not induce detectable microchimerism in this group of recipients. These data clearly demonstrate that the presence of microchimerism is common following administration of donor cells, but that its presence is not an absolute requirement for the long-term survival of allografts.     

Hindering phenomena in group supervision: Implications for practice.

Although group supervision is practiced extensively, research on the subject remains scant. This study identified group supervision phenomena that hinder learning. Counseling and counseling psychology graduate students identified 61 group supervision experiences that they felt interfered with their learning. Then, 14 of the 49 original participants sorted the 61 phenomena on the basis of similarity. Hierarchical cluster analysis was used to identify 5 types of hindering phenomena: between-member problems, problems with supervisors, supervisee anxiety and other perceived negative affects, logistical constraints, and poor group time management. Implications for supervisors, supervisees, and training programs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and Characterization of A New Blue-Light-Emitting Polyimide

5,5'-Bis(4-aminophenyl)-2,2'-bifuryl (PFDA) with a well-defined conjugation length was synthesized, and its soluble poly(amic acid) was prepared by polycondensation with pyromellitic dianhydride (PMDA). The PMDA-PFDA polyimide films were obtained from the poly(amic acid) solution through a conventional spin-casting, baking, and thermal imidization process. The PFDA monomer exhibits intense blue photoluminescence with a maximum at 442 nm in a high quantum yield of 0.92, whereas its polyimide film also emits intense blue photoluminescence with double peak maxima at 419 and 436 nm. The polyimide is insoluble in common organic solvents and thermally stable up to 370 degreesC. Overall, the PMDA-PFDA polyimide can be considered to be a potential candidate material for fabricating optoelectronic devices that emit blue light.     

General Strength Criterion for Geomaterials

This note presents the results of a study on the variation of the strength of geomaterials. A general isotropic strength criterion is proposed which unifies the peak strength and critical state (or steady state) strength into one strength criterion. The proposed criterion describes the strength of a geomaterial in terms of its current stress state, its current voids ratio, and the bonding of its constituents. The proposed criterion has been applied to sand, clay, cemented sand and rocks. Based on comparisons presented between theoretical simulations and experimental data, it is seen that the proposed criterion describes successfully the isotropic strength of all these materials for general stress conditions.