Varvara A. Kirchner

Opioid Drug Abuse and Modulation of Immune Function: Consequences in the Susceptibility to Opportunistic Infections

Infection rate among intravenous drug users (IDU) is higher than the general public, and is the major cause of morbidity and hospitalization in the IDU population. Epidemiologic studies provide data on increased prevalence of opportunistic bacterial infections such as TB and pneumonia, and viral infections such as HIV-1 and hepatitis in the IDU population. An important component in the intravenous drug abuse population and in patients receiving medically indicated chronic opioid treatment is opioid withdrawal. Data on bacterial virulence in the context of opioid withdrawal suggest that mice undergoing withdrawal had shortened survival and increased bacterial load in response to Salmonella infection. As the body of evidence in support of opioid dependency and its immunosuppressive effects is growing, it is imperative to understand the mechanisms by which opioids exert these effects and identify the populations at risk that would benefit the most from the interventions to counteract opioid immunosuppressive effects. Thus, it is important to refine the existing animal model to closely match human conditions and to cross-validate these findings through carefully controlled human studies. Better understanding of the mechanisms will facilitate the search for new therapeutic modalities to counteract adverse effects including increased infection rates. This review will summarize the effects of morphine on innate and adaptive immunity, identify the role of the mu opioid receptor in these functions and the signal transduction activated in the process. The role of opioid withdrawal in immunosuppression and the clinical relevance of these findings will also be discussed.

Pancreas Oxygen Persufflation Increases ATP Levels as Shown by Nuclear Magnetic Resonance

BACKGROUND Islet transplantation is a promising treatment for type 1 diabetes. Due to a shortage of suitable human pancreata, high cost, and the large dose of islets presently required for long-term diabetes reversal; it is important to maximize viable islet yield. Traditional methods of pancreas preservation have been identified as suboptimal due to insufficient oxygenation. Enhanced oxygen delivery is a key area of improvement. In this paper, we explored improved oxygen delivery by persufflation (PSF), ie, vascular gas perfusion. METHODS Human pancreata were obtained from brain-dead donors. Porcine pancreata were procured by en bloc viscerectomy from heparinized donation after cardiac death donors and were either preserved by either two-layer method (TLM) or PSF. Following procurement, organs were transported to a 1.5-T magnetic resonance (MR) system for (31)P nuclear magnetic resonance spectroscopy to investigate their bioenergetic status by measuring the ratio of adenosine triphosphate to inorganic phosphate (ATP:P(i)) and for assessing PSF homogeneity by MRI. RESULTS Human and porcine pancreata can be effectively preserved by PSF. MRI showed that pancreatic tissue was homogeneously filled with gas. TLM can effectively raise ATP:P(i) levels in rat pancreata but not in larger porcine pancreata. ATP:P(i) levels were almost undetectable in porcine organs preserved with TLM. When human or porcine organs were preserved by PSF, ATP:P(i) was elevated to levels similar to those observed in rat pancreata. CONCLUSION The methods developed for human and porcine pancreas PSF homogeneously deliver oxygen throughout the organ. This elevates ATP levels during preservation and may improve islet isolation outcomes while enabling the use of marginal donors, thus expanding the usable donor pool.

Persufflation Improves Pancreas Preservation When Compared With the Two-Layer Method

Islet transplantation is emerging as a promising treatment for patients with type 1 diabetes. It is important to maximize viable islet yield for each organ due to scarcity of suitable human donor pancreata, high cost, and the large dose of islets required for insulin independence. However, organ transport for 8 hours using the two-layer method (TLM) frequently results in low islet yields. Since efficient oxygenation of the core of larger organs (eg, pig, human) in TLM has recently come under question, we investigated oxygen persufflation as an alternative way to supply the pancreas with oxygen during preservation. Porcine pancreata were procured from donors after cardiac death and preserved by either TLM or persufflation for 24 hours and subsequently fixed. Biopsies collected from several regions of the pancreas were sectioned, stained with hematoxylin and eosin, and evaluated by a histologist. Persufflated tissues exhibited distended capillaries and significantly less autolysis/cell death relative to regions not exposed to persufflation or to tissues preserved with TLM. The histology presented here suggests that after 24 hours of preservation, persufflation dramatically improves tissue health when compared with TLM. These results indicate the potential for persufflation to improve viable islet yields and extend the duration of preservation, allowing more donor organs to be utilized.

Continuous Real-time Viability Assessment of Kidneys Based on Oxygen Consumption

BACKGROUND Current ex vivo quality assessment of donor kidneys is limited to vascular resistance measurements and histological analysis. New techniques for the assessment of organ quality before transplantation may further improve clinical outcomes while expanding the depleted deceased-donor pool. We propose the measurement of whole organ oxygen consumption rate (WOOCR) as a method to assess the quality of kidneys in real time before transplantation. METHODS Five porcine kidneys were procured using a donation after cardiac death (DCD) model. The renal artery and renal vein were cannulated and the kidney connected to a custom-made hypothermic machine perfusion (HMP) system equipped with an inline oxygenator and fiber-optic oxygen sensors. Kidneys were perfused at 8 degrees C, and the perfusion parameters and partial oxygen pressures (pO(2)) were measured to calculate WOOCR. RESULTS Without an inline oxygenator, the pO(2) of the perfusion solution at the arterial inlet and venous outlet diminished to near 0 within minutes. However, once adequate oxygenation was provided, a significant pO(2) difference was observed and used to calculate the WOOCR. The WOOCR was consistently measured from presumably healthy kidneys, and results suggest that it can be used to differentiate between healthy and purposely damaged organs. CONCLUSIONS Custom-made HMP systems equipped with an oxygenator and inline oxygen sensors can be applied for WOOCR measurements. We suggest that WOOCR is a promising approach for the real-time quality assessment of kidneys and other organs during preservation before transplantation.

Who's covering our loved ones: surprising barriers in the sign-out process

BACKGROUND The aims of this study were to characterize obstacles affecting current sign-out practices and to evaluate the potential impact of standardized sign-out guidelines. METHODS In June 2011, detailed guidelines for transitions of care were implemented, and a 29-item multiple-choice survey was developed to assess sign-out practices, attitudes, and barriers to effective communication. Surveys were administered to residents and nurses at 3 time points. Comparisons between time points were assessed using t tests and χ(2) tests (α = .05). RESULTS Guideline implementation achieved nonsignificant improvements in satisfaction with sign-outs, perceptions of patient safety, adequacy of information provided in sign-out, and patient knowledge by on-call residents. On follow-up, concerns surfaced regarding less complete sign-out processes due to new duty-hour restrictions. CONCLUSIONS Guideline implementation mildly improved perceptions of safety and adequacy of sign-out; however, persistent barriers to continuity of care remain. Sign-out standardization may not adequately ensure patient safety, and further efforts to improve handoff processes are in need.

Long-term Outcomes for Living Pancreas Donors in the Modern Era.

Background Living donor segmental pancreas transplants (LDSPTx) have been performed selectively to offer a preemptive transplant option for simultaneous pancreas-kidney recipients and to perform a single operation decreasing the cost of pancreas after kidney transplant. For solitary pancreas transplants, this option historically provided a better immunologic match. Although short-term donor outcomes have been documented, there are no long-term studies. Methods We studied postdonation outcomes in 46 segmental pancreas living donors. Surgical complications, risk factors (RF) for development of diabetes mellitus (DM) and quality of life were studied. A risk stratification model (RSM) for DM was created using predonation and postdonation RFs. Recipient outcomes were analyzed. Results Between January 1, 1994 and May 1, 2013, 46 LDSPTx were performed. Intraoperatively, 5 (11%) donors received transfusion. Overall, 9 (20%) donors underwent splenectomy. Postoperative complications included: 6 (13%) peripancreatic fluid collections and 2 (4%) pancreatitis episodes. Postdonation, DM requiring oral hypoglycemics was diagnosed in 7 (15%) donors and insulin-dependent DM in 5 (11%) donors. RSM with three predonation RFs (oral glucose tolerance test, basal insulin, fasting plasma glucose) and 1 postdonation RF, greater than 15% increase in body mass index from preoperative (&Dgr; body mass index >15), predicted 12 (100%) donors that developed postdonation DM. Quality of life was not significantly affected by donation. Mean graft survival was 9.5 (±4.4) years from donors without and 9.6 (±5.4) years from donors with postdonation DM. Conclusions LDSPTx can be performed with good recipient outcomes. The donation is associated with donor morbidity including impaired glucose control. Donor morbidity can be minimized by using RSM and predonation counseling on life style modifications postdonation.

Beta-cell replacement therapy: current outcomes and future landscape.

Purpose of reviewThis article provides a summary of the current outcomes of &bgr;-cell replacement strategies, an algorithm for choosing a specific modality while highlighting associated advantages and disadvantages, and outlines remaining challenges and areas of active investigation in &bgr;-cell replacement therapy. Recent findingsThe most recent reports of islet cell allotransplantation have shown improvements over previous eras and now rival some outcomes of pancreas alone transplantation. Active areas of investigation are focused on improving techniques for islet isolation, graft monitoring, and managing challenges posed by the innate and alloimmune systems. SummaryPatients with insulin-dependent diabetes who continue to experience life threatening hypoglycemia despite maximal medical management can benefit from &bgr;-cell replacement. Emerging nontransplant technologies have not provided a physiologic euglycemic state to the extent offered by transplantation. Islet transplantation eliminates hypoglycemic episodes/unawareness, facilitates normalization of hemoglobin A1c (HbA1c), decreases microvascular disease progression, and improves quality of life for patients with problematic diabetes. Mid- and long-term outcomes of islet transplantation performed at expert centers approximate those of registry reports of solitary pancreas transplant, whereas the complication profile is quite favorable.

Protective role of hypoxia-inducible factor-1α-dependent CD39 and CD73 in fulminant acute liver failure

Abstract Acute liver failure (ALF) is a severe life‐threatening disease which usually arises in patients with‐irreversible liver illnesses. Although human ectonucleotide triphosphate diphosphohydrolase‐1, E‐NTPDase1 (CD39) and ecto‐5′‐nucleotidase, Ecto5′NTase (CD73) are known to protect tissues from ALF, the expression and function of CD39 and CD73 during ALF are currently not fully investigated. We tested whether CD39 and CD73 are upregulated by hypoxia inducible factor (HIF)‐1&agr;, and improve ischemic tolerance to ALF. To test our hypothesis, liver biopsies were obtained and we found that CD39 and CD73 mRNA and proteins from human specimens were dramatically elevated in ALF. We investigated that induction of CD39 and CD73 in ALF‐related with wild type mice. In contrast, deletion of cd39 and cd73 mice has severe ALF. In this study, we concluded that CD39 and CD73 are molecular targets for the development of drugs for ALF patients care. Graphical abstract Figure. No Caption available. HighlightsHIF‐1a is stabilized during acute liver failureUpregulation of CD39 and CD73 following acute liver failureCD39 and CD73 are transcriptionally induced by HIF‐1aDeletion of Cd39 and CD73 aggravates murine acute liver failureDMOG treatment induces HIF‐1a stabilization, CD39 and CD73 during acute liver failure in WT mice

Surgical protocol involving the infusion of paramagnetic microparticles for preferential incorporation within porcine islets.

INTRODUCTION Despite significant advances, widespread applicability of islet cell transplantation remains elusive. Refinement of current islet isolation protocols may improve transplant outcomes. Islet purification by magnetic separation has shown early promise. However, surgical protocols must be optimized to maximize the incorporation of paramagnetic microparticles (MP) within a greater number of islets. This study explores the impact of MP concentration and infusion method on optimizing MP incorporation within islets. METHODS Five porcine pancreata were procured from donors after cardiac death. Splenic lobes were isolated and infused with varying concentrations of MP (8, 16, and 32 × 10(8) MP/L of cold preservation solution) and using one of two delivery techniques (hanging bag versus hand-syringe). After procurement and infusion, pancreata were stored at 0°C to 4°C during transportation (less than 1 hour), fixed in 10% buffered formalin, and examined by standard magnetic resonance imaging (MRI) and histopathology. RESULTS T2*-weighted MRI showed homogeneous distribution of MP in all experimental splenic lobes. In addition, histologic analysis confirmed that MP were primarily located within the microvasculature of islets (82% to 85%), with few MP present in acinar tissue (15% to 18%), with an average of five to seven MP per islet (within a 5-μm thick section). The highest MP incorporation was achieved at a concentration of 16 × 10(8) MP/L using the hand-syringe technique. CONCLUSION This preliminary study suggests that optimization of a surgical protocol, MP concentrations, and applied infusion pressures may enable more uniform distribution of MP in the porcine pancreas and better control of MP incorporation within islets. These results may have implications in maximizing the efficacy of islet purification by magnetic separation.

Resolution of Hepatic Venous Congestion Following Gradual Occlusion of Middle Hepatic Vein Interposition Graft in Living Donor Liver Transplantation.

BACKGROUND The middle hepatic vein (MHV) interposition vessel graft (IVG) is often occluded within a few months after living-donor liver transplantation (LDLT). We aimed to assess the mechanisms of resolving the hepatic venous congestion (HVC) that develops after gradual occlusion of the MHV-IVG. MATERIAL AND METHODS This study comprised two parts. Part I involved an assessment of the process of HVC resolution in the remnant right liver after donation of an extended left liver graft (n=100). Part II involved an evaluation of the timing and patterns of gradual MHV-IVG occlusion and HVC resolution in LDLT recipients (n=100). RESULTS In Part I, the analysis of 1-week dynamic computed tomography (CT) showed pre-existing collaterals in 8, appropriate compensation in 44, and HVC in 48 patients. In Part II, reconstruction of a segment V vein (V5) and a segment VIII vein (V8) was the most common reconstruction type (n=65). The patency rates of MHV-IVG were 90% at 3 months, 65% at 6 months, 37% at 12 months, and 18% at 24 months. The patency rate of V5 was inferior to that of V8. CT imaging analysis indicated that extrinsic compression of IVG, development of intrahepatic collaterals, and IVG shrinkage were the main mechanisms underlying late MHV-IVG occlusion. Moreover, the timing of MHV-IVG occlusion was well correlated with that of neo-collateralization. CONCLUSIONS MHV-IVG reconstruction effectively prevents HVC in LDLT. Although gradual MHV-IVG occlusion is well compensated by neo-collateralization, we believe that the patency of the IVG should be maintained for at least 6 months after LDLT.