Adaptively Weighted Top-N Recommendation for Organ Matching

Reducing the shortage of organ donations to meet the demands of patients on the waiting list has being a major challenge in organ transplantation. Because of the shortage, organ matching decision is the most critical decision to assign the limited viable organs to the most “suitable” patients. Currently, organ matching decisions are only made by matching scores calculated via scoring models, which are built by the first principles. However, these models may disagree with the actual post-transplantation matching performance (e.g., patient's post-transplant quality of life (QoL) or graft failure measurements). In this paper, we formulate the organ matching decision-making as a top-N recommendation problem and propose an Adaptively Weighted Top-N Recommendation (AWTR) method. AWTR improves performance of the current scoring models by using limited actual matching performance in historical datasets as well as the collected covariates from organ donors and patients. AWTR sacrifices the overall recommendation accuracy by emphasizing the recommendation and ranking accuracy for top-N matched patients. The proposed method is validated in a simulation study, where KAS [ 60 ] is used to simulate the organ-patient recommendation response. The results show that our proposed method outperforms seven state-of-the-art top-N recommendation benchmark methods.

Women and Minorities as Living Organ Donors

In this chapter, two demographic traits of living donors are observed: the over-representation of women and the under-representation of Blacks. This raises the question of whether these differences should be considered a disparity or a preference. A traditional bioethics approach would state that as long as living donors believe that the benefits of participation outweigh the risks and harms (beneficence) and the donors give a voluntary and informed consent (autonomy or, more accurately, respect for persons), then the demographics reflect a mere difference in preferences. Such an analysis, however, ignores the social, economic, and cultural determinants as well as various forms of structural discrimination (such as racism and sexism) that may imply that the distribution is less voluntary than may appear initially. The distribution also raises justice concerns regarding the fair recruitment and selection of living donors and their recipients. A vulnerabilities analysis can help explain the demographics of living donation.

The Living Organ Donor as Patient

This is a book about living solid organ donors as patients in their own right. This book is premised on the supposition that the field of living donor organ transplantation is ethical, even if some specific applications are not, eg, pre-mortem organ procurement of an imminently dying patient. When Joseph Murray performed the first successful living kidney donor transplant in 1954, he thought this would be a temporary stopgap. Today, however, the goal of adequate organ supply without living donors remains elusive. If anything, the supply:demand ratio is worse. In this book, a five-principle living donor ethics framework is developed and used to examine the ethical issues raised by living donor selection demographics, innovative attempts to increase living organ donation, and living donor decision-making and risk thresholds. This ethics framework uses the three principles of the Belmont Report modified to organ transplantation (respect for persons, beneficence, and justice) supplemented by the principles of vulnerability and of special relationships creating special obligations. The approach requires that the transplant community fully embraces living organ donors (and prospective living organ donors) as patients to whom special obligations are owed. Only when living organ donors are regarded as patients in their own right and have a living donor advocate team dedicated to their well-being can the moral boundaries of living solid organ donation be determined and realized. This book provides theoretical arguments and practice guidelines, complemented by case studies, to ensure that living donors are given the full respect and care they deserve.

Introduction

This is a book about living solid organ donors as patients in their own right. It is premised on the supposition that the field of living donor organ transplantation is ethical, even if some instantiations are not, eg, pre-mortem organ procurement of an imminently dying patient. In this chapter, the objection to living solid organ donation based on the obligation to do no harm is rejected because it ignores the fact that for many living donors, the benefits outweigh the harms. It is argued that the principle of respect for persons permits some living solid organ donation provided that both the donor and the recipient are treated as patients in their own right. This chapter then provides an outline for the rest of the book in which a five-principle living donor ethics framework is developed and applied to various living donor transplant proposals.

Minors as Living Organ Donors

In 1957, three years after the first successful kidney transplant between identical twin brothers, the Supreme Judicial Court in Massachusetts authorized kidney transplantation between three sets of identical twin minors and approved another two dozen living donor transplants involving minor donors over the next twenty years. Today, minors rarely serve as living solid organ donors, and donation by minors is prohibited in much of the world. In this chapter arguments are made to restrict children from serving as living donors except as a last resort. It is also argued that if one embraces the concept of the living donor as patient, then one would not make an exception for living donation by a minor to his or her identical twin sibling.

3D bioprinting in microgravity: An end to organ donor shortages?

Countless lives have been saved with the advent of modern organ transplantation. However, the current shortage of compatible organ donors is limiting the life-saving potential of transplantation. According to the United Network for Organ Sharing, approximately 20 patients die each day in the United States while waiting for a transplant [1]. The discrepancy between supply and demand of organ donors is accentuated by a fundamental ethical dilemma associated with deceased organ donation: one person must die so that another may live [2]. The current viewpoint considers the viability of 3D bioprinting in microgravity as a solution to organ donor shortages. Current alternatives to deceased organ donation, including xenotransplantation and other state-of-the-art bioprinting techniques, are reviewed and compared to bioprinting in microgravity. The limitations of bioprinting within Earth’s gravitational field are also discussed, revealing the need for further research.

Matrix metalloproteinase 2 and 9 enzymatic activities are selectively increased in the myocardium of Chronic Chagas Disease cardiomyopathy patients: role of TIMPs

Chronic Chagas disease (CCC) is an inflammatory dilated cardiomyopathy with a worse prognosis compared to other cardiomyopathies. We show the expression and activity of Matrix Metalloproteinases (MMP) and of their inhibitors TIMP (tissue inhibitor of metalloproteinases) in myocardial samples of end stage CCC, idiopathic dilated cardiomyopathy (DCM) patients, and from organ donors. Our results showed significantly increased mRNA expression of several MMPs, several TIMPs and EMMPRIN in CCC and DCM samples. MMP-2 and TIMP-2 protein levels were significantly elevated in both sample groups, while MMP-9 protein level was exclusively increased in CCC. MMPs 2 and 9 activities were also exclusively increased in CCC. Results suggest that the balance between proteins that inhibit the MMP-2 and 9 is shifted toward their activation. Inflammation-induced increases in MMP-2 and 9 activity and expression associated with imbalanced TIMP regulation could be related to a more extensive heart remodeling and poorer prognosis in CCC patients.