Tracking sentence comprehension: Test-retest reliability in people with aphasia and unimpaired adults.

PURPOSE: Visual-world eyetracking is increasingly used to investigate online language processing in normal and language impaired listeners. Tracking changes in eye movements over time also may be useful for indexing language recovery in those with language impairments. Therefore, it is critical to determine the test-retest reliability of results obtained using this method. METHODS: Unimpaired young adults and people with aphasia took part in two eyetracking sessions spaced about one week apart. In each session, participants completed a sentence-picture matching task in which they listened to active and passive sentences (e.g., The [N1+Auxwoman was] [Vvisiting/visited] [NP/PP2(by) the man]) and selected between two pictures with reversed thematic roles. We used intraclass correlations (ICCs) to examine the test-retest reliability of response measures (accuracy, reaction time (RT)) and online eye movements (i.e., the likelihood of fixating the target picture in each region of the sentence) in each participant group. RESULTS: In the unimpaired adults, accuracy was at ceiling (thus ICCs were not computed), with moderate ICCs for RT (i.e., 0.4 - 0.58) for passive sentences and low (<0.4) for actives. In individuals with aphasia, test-retest reliability was strong (0.590.75) for RT for both sentence types. Similarly, for the unimpaired listeners, reliability of eye movements was moderate for passive sentences (NP/PP2 region) and low in all regions for active sentences. But, for the aphasic participant group, eye movement reliability was excellent for passive sentences (in the first second after sentence end) and strong for active sentences (V and NP/PP2 regions). CONCLUSION: Results indicated moderate-to-low reliability for unimpaired listeners; however, reliable eye movement patterns were detected for processes specific to passive sentences (e.g., thematic reanalysis). In contrast, individuals with aphasia exhibited strong and stable performance across sentence types in response measures and online eye movements. These findings indicate that visual-world eyetracking provides a reliable measure of online sentence comprehension, and thus may be useful for investigating sentence processing changes over time.

Personalized Peptide Arrays for Detection of HLA Alloantibodies in Organ Transplantation.

In organ transplantation, the function and longevity of the graft critically rely on the success of controlling immunological rejection reactivity against human leukocyte antigens (HLA). Histocompatibility guidelines are based on laboratory tests of anti-HLA immunity, which presents either as pre-existing or de novo generated HLA antibodies that constitute a major transplantation barrier. Current tests are built on a single-antigen beads (SAB) platform using a fixed set of ~100 preselected recombinant HLA antigens to probe transplant sera. However, in humans there exist a far greater variety of HLA types, with no two individuals other than identical twins who can share the same combination of HLA sequences. While advanced technologies for HLA typing and direct sequencing can precisely capture any mismatches in DNA sequence between a donor's and recipient's HLA, the SAB assay, due to its limited variety in sequence representation, is unable to precisely detect alloantibodies specifically against the donor HLA mismatches. We sought to develop a complementary method using a different technology to detect and characterize anti-donor HLA antibodies on a personalized basis. The screening tool is a custom peptide array of donor HLA-derived sequences for probing post-transplant sera of the organ recipient to assess the risk for antibody-mediated rejection. On a single array for one donor-recipient pair, up to 600 unique peptides are made based on the donor's HLA protein sequences, each peptide carrying at least one mismatched residue in a 15-amino acid sequence. In our pilot experiments to compare antigen patterns for pre- and post-transplant sera on these arrays, we were able to detect anti-HLA signals with the resolution that also allowed us to pinpoint the immune epitopes involved. These personalized antigen arrays allow high-resolution detection of donor-specific HLA epitopes in organ transplantation.

Nrf2 inactivation enhances placental angiogenesis in a preeclampsia mouse model and improves maternal and fetal outcomes.

Placental activation of the renin-angiotensin system (RAS) plays a key role in the pathogenesis of preeclampsia. Reactive oxygen species (ROS) are thought to affect placental angiogenesis, which is critical for preventing preeclampsia pathology. We examined the role of ROS in preeclampsia by genetically modifying the Keap1-Nrf2 pathway, a cellular antioxidant defense system, in a mouse model of RAS-induced preeclampsia. Nrf2 deficiency would be expected to impair cellular antioxidant responses; however, Nrf2 deficiency in preeclamptic mice improved maternal and fetal survival, ameliorated intra-uterine growth retardation, and augmented oxidative DNA damage. Furthermore, the placentas of Nrf2-deficient mice had increased endothelial cell proliferation with dense vascular networks. In contrast, the placentas of preeclamptic mice with overactive Nrf2 showed repressed angiogenesis, which was associated with decreased expression of genes encoding angiogenic chemokines and cytokines. Our findings support the notion that ROS-mediated signaling is essential for maintaining placental angiogenesis in preeclampsia and may provide mechanistic insight into the negative results of clinical trials for antioxidants in preeclampsia.

A Novel Method for Anti-HLA Antibody Detection Using Personalized Peptide Arrays.

BACKGROUND: HLA mismatches are the primary cause of alloantibody-mediated rejection (AMR) in organ transplantation. To delineate antigenic and immunogenic potentials among individual HLA mismatches, information regarding antibody specificity at the epitope level, instead of the allelic level, is needed. METHODS: This study explores a direct screening method for HLA linear epitopes in kidney transplant patients. We custom synthesized a large panel of 15-residue HLA peptides in an array format and measured alloantibody reactivity to these peptides from the sera of post and/or pretransplant patients. Two design concepts for the arrays were followed: a standard array of a fixed panel of peptides or personalized arrays. The standard array contains 420 peptides derived from a predetermined set of HLA-DQ allelic antigens based on templates also used in the single-antigen beads assay. RESULTS: The array detected distinct antiserum patterns among transplant subjects and revealed epitope levels of specificity largely in accordance with the single-antigen results. Two personalized arrays that each included donor-derived peptides of HLA-A, -B, -C, -DQ, and -DR sequences were separately designed for 2 transplant subjects. The personalized arrays detected de novo antibodies following transplantation. The new method also showed superior sensitivity to a single-antigen assay in one of the cases whose pathological diagnosis of AMR occurred before single-antigen assay could detect antibodies. CONCLUSIONS: This pilot study proved the feasibility of using personalized peptide arrays to achieve detection of alloantibodies for linear HLA epitopes associated with distinct donor-recipient mismatches. Single or multiple reactive epitopes may occur on an individual HLA molecule, and donor-specific HLA-DQ-reactivity among 5 kidney transplant subjects revealed patterns of shared epitopes.