Glial Tumor Necrosis Factor Alpha (TNFα) Generates Metaplastic Inhibition of Spinal Learning

Injury-induced overexpression of tumor necrosis factor alpha (TNFα) in the spinal cord can induce chronic neuroinflammation and excitotoxicity that ultimately undermines functional recovery. Here we investigate how TNFα might also act to upset spinal function by modulating spinal plasticity. Using a model of instrumental learning in the injured spinal cord, we have previously shown that peripheral intermittent stimulation can produce a plastic change in spinal plasticity (metaplasticity), resulting in the prolonged inhibition of spinal learning. We hypothesized that spinal metaplasticity may be mediated by TNFα. We found that intermittent stimulation increased protein levels in the spinal cord. Using intrathecal pharmacological manipulations, we showed TNFα to be both necessary and sufficient for the long-term inhibition of a spinal instrumental learning task. These effects were found to be dependent on glial production of TNFα and involved downstream alterations in calcium-permeable AMPA receptors. These findings suggest a crucial role for glial TNFα in undermining spinal learning, and demonstrate the therapeutic potential of inhibiting TNFα activity to rescue and restore adaptive spinal plasticity to the injured spinal cord. TNFα modulation represents a novel therapeutic target for improving rehabilitation after spinal cord injury

The cervical lymph node preparation: A novel approach to study lymphocyte homing by intravital microscopy

Objective: Lymphocyte recirculation constitutes an integral part of the adaptive immune system. Blood-borne lymphocytes migrate into secondary lymphoid organs, crossing the vascular wall of site-specific high endothelial venules (HEVs). We created a preparation of the cervical lymph node in mice to study lymphocyte homing in vivo. Methods and Results: Our novel approach allowed the detailed analysis of hemodynamics and lymphocyte-HEV endothelium interactions by means of intravital fluorescence microscopy. We confirm the key roles of L-selectin and LFA-1 for lymphocyte homing. Blockade of L-selectin function inhibited lymphocyte rolling and firm adhesion by 92 % and 66%. In LFA-1-deficient mice, lymphocyte firm adhesion was reduced by 70%. In addition to the microcirculation studies, the cervical lymph node preparation allowed for visualization of afferent lymphatic transport, which is mainly derived from the oral mucosa. Conclusion: This study reports a novel technical tool for the detailed in vivo analysis of adaptive immune responses

Concepts of Aortic Valve Repair

Aortic valve (AV) sparing and repair procedures are advantageous alternatives to valve replacement in patients with aortic aneurysm and/or aortic regurgitation. A successful sparing or repair strategy proceeds first from a clear understanding of the peculiar anatomy and function of the AV and of the possible mechanisms of valve dysfunction. The AV is a functional unit composed of the valve cusps and the functional aortic annulus (FAA). Lesion on any or more of these components can induce aortic insufficiency. A functional classification of aortic regurgitation identifies three main mechanisms of AV regurgitation although more than one type of lesion can coexist in a patient. The goal of AV repair is to restore a normal surface of coaptation by restoring normal geometry between the leaflets and the FAA, while preserving normal mobility of the AV cusps. We present in detail our preferred surgical techniques for valve-sparing root replacement (VSRR) and repair of the AV cusps in the context of tricuspid AV. Further, we discuss the peculiarities of the VSRR and repair techniques in the context of bicuspid AV including our preferred approach to the bicuspid aortic dilatation

Pulmonary retransplantation:Predictors of graft function and survival in 230 patients

Background. Despite improving results in lung transplantation, a significant number of grafts fail early or late postoperatively. The pulmonary retransplant registry was founded in 1991 to determine the predictors of outcome after retransplantation. We hypothesized that ambulatory status of the recipient and center retransplant volume, which had been previously shown to predict survival after retransplantation, would also be associated with improved graft function postoperatively. Methods. Two hundred thirty patients underwent retransplantation in 47 centers from 1985 to 1996. Logistic regression methods were used to determine variables associated with, and predictive of, survival and lung function after retransplantation. Results. Kaplan-Meier survival was 47% +/- 3%, 40% +/- 3%, and 33% +/- 4% at 1, 2, and 3 years, respectively. On multivariable analysis, the predictors of survival included ambulatory status or lack of ventilator support preoperatively (p = 0.005; odds ratio, 1.62; 95% confidence interval, 1.15 to 2.27), followed by retransplantation after 1991 (p = 0.048; odds ratio, 1.41; 95% confidence interval, 1.003 to 1.99). Ambulatory, nonventilated patients undergoing retransplantation after 1991 had a 1-year survival of 64% +/- 5% versus 33% +/- 4% for nonambulatory, ventilated recipients. Eighty-one percent, 70%, 62%, and 56% of survivors were free of bronchiolitis obliterans syndrome at 1, 2, 3, and 4 years after retransplantation, respectively. Factors associated with freedom from stage 3 (severe) bronchiolitis obliterans syndrome at 2 years after retransplantation included an interval between transplants greater than 2 years (p = 0.01), the lack of ventilatory support before retransplantation (p = 0.03), increasing retransplant experience within each center (fifth and higher retransplant patient, p = 0.04), and total center volume of five or more retransplant operations (P = 0.05). Conclusions. Nonambulatory, ventilated patients should not be considered for retransplantation with the same priority as other candidates. The best intermediate-term functional results occurred in more experienced centers, in nonventilated patients, and in patients undergoing retransplantation more than 2 years after their first transplant. In view of the scarcity of lung donors, patient selection for retransplantation should remain strict and should be guided by the outcome data reviewed in this article. (C) 1998 by The Society of Thoracic Surgeons