Abstract: Chronic rejection is the single most important cause of death in lung transplant recipients after the first postoperative year, resulting in a 5-year survival rate of about 50%, which is far behind that of other solid organ transplantations. Chronic rejection histologically presents as obliterative bronchiolitis, a scarring of the terminal bronchioles. Because obliterative bronchiolitis is not consistently detectable by biopsies, spirometry is routinely used as a clinical surrogate marker to diagnose chronic rejection and to evaluate its evolution after onset. As such, a progressive, obstructive spirometry in absence of all other causes, defined as bronchiolitis obliterans syndrome (BOS), is considered to reflect chronic rejection after lung transplantation. BOS has a 5-years prevalence of about 45% and is thought to be the final common end-point of various allo-immunologic and non-allo-immunologic injuries to the pulmonary allograft, many of which are still unclear. Most preventive and therapeutic strategies for this complex process have been largely unsuccessful. However, the introduction of the neo-macrolide antibiotic azithromycin in the field of lung transplantation as of 2003 made it clear that some 40% of patients with established BOS might in fact benefit from such therapy. Particularly in patients with an increased broncho-alveolar lavage neutrophilia (i.e. 15 to 20% or more), azithromycin treatment could result in an increase of forced expiratory volume in one second (FEV1) of 10% or more. Considering the substantial morbidity and mortality associated with BOS, together with the enormous health-care costs (attributable to frequent hospitalizations and diagnostic procedures in patients with chronic rejection), this doctoral research project investigates the role of probable non-allo-immunologic risk factors for post-transplant airway neutrophilia and their importance for allograft outcome (BOS, survival). Furthermore, we investigated the potential of azithromycin for improving allograft function (FEV1) and patient outcome (survival) in established BOS and, perhaps most importantly, whether prophylactic therapy with azithromycin actually may prevent BOS and how this would influence established risk factors for BOS after lung transplantation.

Abstract: Prior studies have demonstrated that the firing rate of cortical neurons can be volitionally modulated by a subject to generate a controllable output signal; this neural output signal can then be manipulated to direct a robotic arm, a cursor on a computer screen, or other interface device. The burgeoning field of neural control has led to a number of innovative applications, known more commonly as neuroprosthetic devices. Neuroprosthetic devices have the potential to return some degree of functionality to the over 250,000 Americans with incapacitating spinal cord injuries, or allow healthy subjects to control electronic devices in their everyday lives. The research presented here consists of three studies focused on improving the current generation of neuroprosthetic devices.
In the first study, we introduced and evaluated a Bayesian maximum-likelihood estimation (bMLE) strategy to identify optimized training data for neuroprosthetic devices. By limiting initial decoding assumptions and training only on relevant neural data, accurate neural-control was possible with as few as two neurons, using minimal training data and no a-priori¬ movement measurements for calibration. Moreover, implanted subjects obtained useful prosthetic control using local field potentials and neurons from cingulate cortex as input.

In the second study, we refined a method to electrochemically deposit surfactant-templated ordered poly(3,4-ethylenedioxythiophene) (PEDOT) films on the recording sites of standard “Michigan” probes, and evaluated the in vivo efficacy of these modified sites in recording chronic neural activity. PEDOT sites were found to outperform control sites in terms of signal-to-noise ratio and number of viable unit potentials - thereby improving the quality of neural input sources to the neuroprosthetic device.

In the third study, we evaluated a technique known as common average referencing (CAR) to generate a more ideal reference electrode for microelectrode recordings. CAR was found to drastically outperform standard types of electrical referencing, reducing noise by more than 30 percent. As a result of the reduced noise floor, arrays referenced to a CAR yielded almost 60 percent more discernible neural units than traditional methods of electrical referencing – again improving the quality of neural input sources to a neuroprosthetic device.

Abstract: In this study, the technical feasibility of coconut shell charcoal (CSC), commercial activated carbon (CAC), and zeolite for Cr(VI) removal from contaminated wastewater was investigated using batch studies (Cr concentration from 5 to 25 mg/l) and column operation.

Surface modifications of CSC and CAC with chitosan and oxidizing agents (sulfuric acid and/or nitric acid), respectively, were also conducted to improve their removal performance, while treatment of zeolite with NaCl was performed. Using synthetic and real wastewater, their removal performances on Cr are evaluated and statistically compared. Both Langmuir and Freundlich isotherms were used to understand the adsorption mechanism and kinetics of Cr removal by all adsorbents.

It is conclusively evident that the chemical modification of adsorbents significantly improved their removal capabilities. Both CSC and CAC, which have been oxidized with nitric acid, have higher Cr adsorption capacities (CSC: 10.88, CAC: 15.47 mg/g) than those oxidized with sulfuric acid (CSC: 4.05, CAC: 8.94 mg/g) and non-treated coconut shell charcoal coated with chitosan (CSCCC: 3.65 mg/g), respectively. It is important to note that the Cr adsorption capacities of all types of adsorbents vary, depending on the characteristics of individual adsorbent, the extent of surface modifications, and the initial concentration of chromium.