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Integrin-mediated cell attachment rapidly induces tyrosine kinase signaling. Despite years of research, the role of this signaling in integrin activation and focal adhesion assembly is unclear. We provide evidence that the Src-family kinase (SFK) substrate Cas (Crk-associated substrate, p130Cas, BCAR1) is phosphorylated and associated with its Crk/CrkL effectors in clusters that are precursors of focal adhesions. The initial phospho-Cas clusters contain integrin β1 in its inactive, bent closed, conformation. Later, phospho-Cas and total Cas levels decrease as integrin β1 is activated and core focal adhesion proteins including vinculin, talin, kindlin, and paxillin are recruited. Cas is required for cell spreading and focal adhesion assembly in epithelial and fibroblast cells on collagen and fibronectin. Cas cluster formation requires Cas, Crk/CrkL, SFKs, and Rac1 but not vinculin. Rac1 provides positive feedback onto Cas through reactive oxygen, opposed by negative feedback from the ubiquitin proteasome system. The results suggest a two-step model for focal adhesion assembly in which clusters of phospho-Cas, effectors and inactive integrin β1 grow through positive feedback prior to integrin activation and recruitment of core focal adhesion proteins. [ABSTRACT FROM AUTHOR]

Background: A low prevalence of high-level clinical studies in the surgical literature has been reported previously. We reviewed a recent sample of surgical publications to assess the current status of clinical research. Study design: A 3-month sample of journal articles in Archives of Surgery, Surgery, and Annals of Surgery in 2005 was evaluated by two independent reviewers to determine the distribution of articles in established evidence classes. Results: A total of 133 publications were identified in the three journals during the time periods reviewed, including 101 clinical articles and 30 basic science articles. Among the clinical papers, there were 8 class I studies (7.9%), 34 class II studies (33.7%), and more than half were class III studies (59 of 101, or 58.4%). Conclusions: The low prevalence of high-level evidence to guide surgical management of patients persists in major general surgery journals. We believe that education about proper research methodology is not only important for researchers, but is also important for practicing surgeons, and can have important health policy implications as well. [Copyright &y& Elsevier]

Integrin adhesion complexes regulate cytoskeletal dynamics during cell migration. Adhesion activates phosphorylation of integrin-associated signaling proteins, including Cas (p130Cas, BCAR1), by Src-family kinases. Cas regulates leading-edge protrusion and migration in cooperation with its binding partner, BCAR3. However, it has been unclear how Cas and BCAR3 cooperate. Here, using normal epithelial cells, we find that BCAR3 localization to integrin adhesions requires Cas. In return, Cas phosphorylation, as well as lamellipodia dynamics and cell migration, requires BCAR3. These functions require the BCAR3 SH2 domain and a specific phosphorylation site, Tyr 117, that is also required for BCAR3 downregulation by the ubiquitin-proteasome system. These findings place BCAR3 in a co-regulatory positive-feedback circuit with Cas, with BCAR3 requiring Cas for localization and Cas requiring BCAR3 for activation and downstream signaling. The use of a single phosphorylation site in BCAR3 for activation and degradation ensures reliable negative feedback by the ubiquitin-proteasome system. [ABSTRACT FROM AUTHOR]

The broadly neutralizing antibody (bnAb) VRC01 is being evaluated for its efficacy to prevent HIV-1 infection in the Antibody Mediated Prevention (AMP) trials. A secondary objective of AMP utilizes sieve analysis to investigate how VRC01 prevention efficacy (PE) varies with HIV-1 envelope (Env) amino acid (AA) sequence features. An exhaustive analysis that tests how PE depends on every AA feature with sufficient variation would have low statistical power. To design an adequately powered primary sieve analysis for AMP, we modeled VRC01 neutralization as a function of Env AA sequence features of 611 HIV-1 gp160 pseudoviruses from the CATNAP database, with objectives: (1) to develop models that best predict the neutralization readouts; and (2) to rank AA features by their predictive importance with classification and regression methods. The dataset was split in half, and machine learning algorithms were applied to each half, each analyzed separately using cross-validation and hold-out validation. We selected Super Learner, a nonparametric ensemble-based cross-validated learning method, for advancement to the primary sieve analysis. This method predicted the dichotomous resistance outcome of whether the IC50 neutralization titer of VRC01 for a given Env pseudovirus is right-censored (indicating resistance) with an average validated AUC of 0.868 across the two hold-out datasets. Quantitative log IC50 was predicted with an average validated R2 of 0.355. Features predicting neutralization sensitivity or resistance included 26 surface-accessible residues in the VRC01 and CD4 binding footprints, the length of gp120, the length of Env, the number of cysteines in gp120, the number of cysteines in Env, and 4 potential N-linked glycosylation sites; the top features will be advanced to the primary sieve analysis. This modeling framework may also inform the study of VRC01 in the treatment of HIV-infected persons. [ABSTRACT FROM AUTHOR]

Background: More than 20,000 candidates for kidney transplantation in the United States are sensitized to HLA and may have a prolonged wait for a transplant, with a reduced transplantation rate and an increased rate of death. One solution is to perform live-donor renal transplantation after the depletion of donor-specific anti-HLA antibodies. Whether such antibody depletion results in a survival benefit as compared with waiting for an HLA-compatible kidney is unknown. Methods: We used a protocol that included plasmapheresis and the administration of low-dose intravenous immune globulin to desensitize 211 HLA-sensitized patients who subsequently underwent renal transplantation (treatment group). We compared rates of death between the group undergoing desensitization treatment and two carefully matched control groups of patients on a waiting list for kidney transplantation who continued to undergo dialysis (dialysis-only group) or who underwent either dialysis or HLA-compatible transplantation (dialysis-or-transplantation group). Results: In the treatment group, Kaplan–Meier estimates of patient survival were 90.6% at 1 year, 85.7% at 3 years, 80.6% at 5 years, and 80.6% at 8 years, as compared with rates of 91.1%, 67.2%, 51.5%, and 30.5%, respectively, for patients in the dialysis-only group and rates of 93.1%, 77.0%, 65.6%, and 49.1%, respectively, for patients in the dialysis-or-transplantation group (P<0.001 for both comparisons). Conclusions: Live-donor transplantation after desensitization provided a significant survival benefit for patients with HLA sensitization, as compared with waiting for a compatible organ. By 8 years, this survival advantage more than doubled. These data provide evidence that desensitization protocols may help overcome incompatibility barriers in live-donor renal transplantation. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the Charles T. Bauer Foundation.) [ABSTRACT FROM PUBLISHER]

Context First proposed 2 decades ago, live kidney paired donation (KPD) was considered a promising new approach to addressing the shortage of organs for transplantation. Ethical, administrative, and logistical barriers initially proved formidable and prevented the implementation of KPD programs in the United States. Objective To determine the feasibility and effectiveness of KPD for the management of patients with incompatible donors. Design, Setting, and Patients Prospective series of paired donations matched and transplanted from a pool of blood type or crossmatch incompatible donors and recipients with end-stage renal disease (6 conventional and 4 unconventional KPD transplants) at a US tertiary referral center (between June 2001 and November 2004) with expertise in performing transplants in patients with high immunologic risk. Intervention Kidney paired donation and live donor renal transplantation. Main Outcome Measures Patient survival, graft survival, serum creatinine levels, rejection episodes. Results A total of 22 patients received transplants through 10 paired donations including 2 triple exchanges at Johns Hopkins Hospital. At a median follow-up of 13 months (range, 1-42 months), the patient survival rate was 100% and the graft survival rate was 95.5%. Twenty-one of the 22 patients have functioning grafts with a median 6-month serum creatinine level of 1.2 mg/dL (range, 0.8-1.8 mg/dL) (106.1 μmol/L [range, 70.7-159.1 μmol/L]). There were no instances of antibody-mediated rejection despite the inclusion of 5 patients who were highly sensitized to HLA antigens due to previous exposure to foreign tissue. Four patients developed acute cellular rejection (18%). Conclusions This series of patients who received transplants from a single-center KPD pool provides evidence that recipients with incompatible live donors, even those with rare blood type combinations or high degrees of HLA antigen sensitization, can receive transplants through KPD with graft survival rates that appear to be equivalent to directed, compatible live donor transplants. If these results can be generalized, broader availability of KPD to the estimated 6000 patients with incompatible donors could result in a large expansion of the donor pool. [ABSTRACT FROM AUTHOR]

The article discusses the domino approach to matching living non-directed kidney donations with recipients. Other donation schemes include donor-centric, receiver-centric and sociocentric donation. Domino donation involves a living non-directed donor giving a kidney to a recipient who has a willing but incompatible donor. The incompatible donor then gives their kidney to another recipient with whom they are compatible. Domino donations provides the greatest utility for all concerned, but does limit the autonomy of donation centers.