The Association of Intra-Abdominal Adhesions with Peritoneal Dialysis Catheter-Related Complications

BACKGROUND

This study investigated the association of intra-abdominal adhesions with the risk of peritoneal dialysis (PD) catheter complications.

METHODS

Individuals undergoing laparoscopic PD catheter insertion were prospectively enrolled from eight centers in Canada and the United States. Patients were grouped based on the presence of adhesions observed during catheter insertion. The primary outcome was the composite of PD never starting, termination of PD, or the need for an invasive procedure caused by flow restriction or abdominal pain.

RESULTS

Seven hundred and fifty-eight individuals were enrolled, of whom 201 (27%) had adhesions during laparoscopic PD catheter insertion. The risk of the primary outcome occurred in 35 (17%) in the adhesion group compared with 58 (10%) in the no adhesion group (adjusted HR, 1.64; 95% confidence interval [CI], 1.05 to 2.55) within 6 months of insertion. Lower abdominal or pelvic adhesions had an adjusted HR of 1.80 (95% CI, 1.09 to 2.98) compared with the no adhesion group. Invasive procedures were required in 26 (13%) and 47 (8%) of the adhesion and no adhesion groups, respectively (unadjusted HR, 1.60: 95% CI, 1.04 to 2.47) within 6 months of insertion. The adjusted odds ratio for adhesions for women was 1.65 (95% CI, 1.12 to 2.41), for body mass index per 5 kg/m 2 was 1.16 (95% CI, 1.003 to 1.34), and for prior abdominal surgery was 8.34 (95% CI, 5.5 to 12.34). Common abnormalities found during invasive procedures included PD catheter tip migration, occlusion of the lumen with fibrin, omental wrapping, adherence to the bowel, and the development of new adhesions.

CONCLUSIONS

People with intra-abdominal adhesions undergoing PD catheter insertion were at higher risk for abdominal pain or flow restriction preventing PD from starting, PD termination, or requiring an invasive procedure. However, most patients, with or without adhesions, did not experience complications, and most complications did not lead to the termination of PD therapy.

Impact of Prior Abdominal Procedures on Peritoneal Dialysis Catheter Outcomes: Findings From the North American Peritoneal Dialysis Catheter Registry

RATIONALE & OBJECTIVE

A history of prior abdominal procedures may influence the likelihood of referral for peritoneal dialysis (PD) catheter insertion. To guide clinical decision making in this population, this study examined the association between prior abdominal procedures and outcomes in patients undergoing PD catheter insertion.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Adults undergoing their first PD catheter insertion between November 1, 2011 and November 1, 2020, at 11 institutions in Canada and the US participating in the International Society for Peritoneal Dialysis (ISPD) North American Catheter Registry.

EXPOSURE

Prior abdominal procedure(s), defined as any procedure that enters the peritoneal cavity.

OUTCOMES

Primary outcome: time to the first of abandonment of the PD catheter, or interruption/termination of PD.

SECONDARY OUTCOMES

rates of emergency room visits, hospitalizations, and procedures.

ANALYTICAL APPROACH

Cumulative incidence curves were used to describe the risk over time and an adjusted Cox proportional hazards model was used to estimate the association between the exposure and primary outcome. Models for count data were used to estimate the associations between the exposure and secondary outcomes.

RESULTS

A total of 855 patients met the inclusion criteria. Thirty-one percent had a history of a prior abdominal procedure and 20% experienced at least one PD catheter-related complication that led to the primary outcome. Prior abdominal procedures were not associated with an increased risk of the primary outcome [Adjusted HR 1.12 (95% CI 0.68-1.84)]. Upper abdominal procedures were associated with a higher adjusted hazard of the primary outcome, but there was no dose-response relationship concerning the number of procedures. There was no association between prior abdominal procedures and other secondary outcomes.

LIMITATIONS

Observational study and cohort limited to sample of patients felt to be potential candidates for PD catheter insertion.

CONCLUSION

A history of prior abdominal procedure(s) does not appear to influence catheter outcomes following PD catheter insertion. Such a history should not be a contraindication to peritoneal dialysis.

Risk of malignancy in patients with chronic kidney disease

Background

Fifteen percent of US adults have chronic kidney disease (CKD). The effect of CKD on the development of different malignancies is unknown. Understanding the effect of CKD on the risk of development of cancer could have important implications for screening and early detection of cancer in these patients.

Methods

Adult CKD patients [estimated GFR (eGFR) <60ml/min/1.73m²] between January 2001 and December 2020 were identified in this single institution study. Patients were divided into four stages of CKD by eGFR. The incidence of cancer and time to development of the first cancer were identified. Multivariable models were used to compare the overall cancer incidence while considering death as a competing risk event and adjusting for relevant covariates (sex, race, diabetes, hypertension, CAD, smoking or not, BMI, and CKD stages). Separate multivariable models of the incidence of cancers were conducted in each age group. Multivariable Cox models were used to fit the overall death adjusting for relevant covariates. Patients were censored at the conclusion of the study period (December 31, 2020). Statistical analysis was performed with SAS software (version 9.4).

Results

Of the 13,750 patients with a diagnosis of CKD in this cohort, 2,758 (20.1%) developed a malignancy. The median time to development of cancer following a diagnosis of CKD was 8.5 years. Factors associated with the risk of developing cancer in CKD patients included increasing age, male sex and worsening chronic kidney disease, while diabetes was associated with a lower risk of malignancy. On multivariate analysis, the factors associated with increased mortality in patients who developed cancer included increasing age, diabetes and lower eGFR.

Conclusion

CKD is an increased risk factor for the development of various malignancies. Age appropriate cancer screening should be aggressively pursued in those with progressive CKD.

The impact of multi-organ transplant allocation priority on waitlisted kidney transplant candidates

Kidney-alone transplant (KAT) candidates may be disadvantaged by the allocation priority given to multi-organ transplant (MOT) candidates. This study identified potential KAT candidates not receiving a given kidney offer due to its allocation for MOT. Using the Organ Procurement and Transplant Network (OPTN) database, we identified deceased donors from 2002 to 2017 who had one kidney allocated for MOT and the other kidney allocated for KAT or simultaneous pancreas-kidney transplant (SPK) (n = 7,378). Potential transplant recipient data were used to identify the "next-sequential KAT candidate" who would have received a given kidney offer had it not been allocated to a higher prioritized MOT candidate. In this analysis, next-sequential KAT candidates were younger (p < .001), more likely to be racial/ethnic minorities (p < .001), and more highly sensitized than MOT recipients (p < .001). A total of 2,113 (28.6%) next-sequential KAT candidates subsequently either died or were removed from the waiting list without receiving a transplant. In a multivariable model, despite adjacent position on the kidney match-run, mortality risk was significantly higher for next-sequential KAT candidates compared to KAT/SPK recipients (hazard ratio 1.55, 95% confidence interval 1.44, 1.66). These results highlight implications of MOT allocation prioritization, and potential consequences to KAT candidates prioritized below MOT candidates.

Advancing Nephrology: Division Leaders Advise ASN

New treatments, new understanding, and new approaches to translational research are transforming the outlook for patients with kidney diseases. A number of new initiatives dedicated to advancing the field of nephrology-from value-based care to prize competitions-will further improve outcomes of patients with kidney disease. Because of individual nephrologists and kidney organizations in the United States, such as the American Society of Nephrology, the National Kidney Foundation, and the Renal Physicians Association, and international nephrologists and organizations, such as the International Society of Nephrology and the European Renal Association-European Dialysis and Transplant Association, we are beginning to gain traction to invigorate nephrology to meet the pandemic of global kidney diseases. Recognizing the timeliness of this opportunity, the American Society of Nephrology convened a Division Chief Retreat in Dallas, Texas, in June 2019 to address five key issues: (1) asserting the value of nephrology to the health system; (2) productivity and compensation; (3) financial support of faculty's and divisions' educational efforts; (4) faculty recruitment, retention, diversity, and inclusion; and (5) ensuring that fellowship programs prepare trainees to provide high-value nephrology care and enhance attraction of trainees to nephrology. Herein, we highlight the outcomes of these discussions and recommendations to the American Society of Nephrology.

Self-care training using the Tablo hemodialysis system

INTRODUCTION

Recently published results of the investigational device exemption (IDE) trial using the Tablo hemodialysis system confirmed its safety and efficacy for home dialysis. This manuscript reports additional data from the Tablo IDE study on the training time required to be competent in self-care, the degree of dependence on health care workers and caregivers after training was complete, and participants' assessment of the ease-of-use of Tablo.

METHODS

We collected data on the time required to set up concentrates and the Tablo cartridge prior to treatment initiation. We asked participants to rate system setup, treatment, and takedown on a Likert scale from 1 (very difficult) to 5 (very simple) and if they had required any assistance with any aspect of treatment over the prior 7 days. In a subgroup of 15 participants, we recorded the number of training sessions required to be deemed competent to do self-care dialysis.

FINDINGS

Eighteen men and 10 women with a mean age of 52.6 years completed the study. Thirteen had previous self-care experience using a different dialysis system. Mean set up times for the concentrates and cartridge were 1.1 and 10.0 minutes, respectively. Participants with or without previous self-care experience had similar set-up times. The mean ease-of-use score was 4.5 or higher on a scale from 1 to 5 during the in-home phase. Sixty-five percent required no assistance at home and on average required fewer than four training sessions to be competent in managing their treatments. Results were similar for participants with or without previous self-care experience.

CONCLUSIONS

Participants in the Tablo IDE trial were able to quickly learn and manage hemodialysis treatments in the home, found Tablo easy to use, and were generally independent in performing hemodialysis.

Patient-reported outcomes from the investigational device exemption study of the Tablo hemodialysis system

INTRODUCTION

We recently completed an Investigational Device Exemption (IDE) study in which 30 patients were enrolled (13 patients previously on home hemodialysis (HHD) and 17 patients new to HHD) and treated with the Tablo Hemodialysis System (Outset Medical, Inc., San Jose, CA) for 8 weeks in-center and 8 weeks in-home with an interim 2-4 week transition period for home training.

METHODS

In addition to assessments of urea kinetics, events related to safety, and operational issues (e.g., alarm resolution), we obtained data on several parameters of health-related quality of life, including time to recovery (TTR), the EQ-5D-5L (a well-validated measure of general health status), and the quality of sleep and related symptoms, to further assess the safety of HHD with Tablo. We compared results obtained during the in-center and in-home phases of the trial.

RESULTS

Twenty-eight of 30 patients (93%) completed all trial periods. Adherence to the prescribed four treatments per week schedule was 96% in-center and 99% in-home. Median TTR was 1.5 hours (10th, 90th percentile range 0.17 to 12, mean TTR 3.68 ± 5.88 hours) during the in-center and 2 hours (10th, 90th percentile range 0 to 6.0, mean TTR 3.04 ± 5.14 hours) during the at-home phase (Wilcoxon signed rank p = 0.57). Median index values on the EQ-5D-5L were similar during the in-center (0.832, 10th, 90th percentile range 0.617 to 1, mean 0.817 ± 0.165) and in-home (0.826, 10th, 90th percentile range 0.603 to 1, mean 0.821 ± 0.163) trial phases (Wilcoxon signed rank p = 0.36). Patients reported feeling alert or well-rested with little difficulty falling or staying asleep or feeling tired and worn out when using Tablo in either environment.

CONCLUSION

When using Tablo in-home, patients reported similar TTR, general health status, and sleep quality and related symptoms compared to using Tablo in-center. (294 words).

Liposuction used to treat deep vascular accesses for hemodialysis

BACKGROUND

Oftentimes, obese dialysis patients develop a viable dialysis access but the access is too deep for cannulation and needs a superficialization procedure.

METHODS

We present our 14-patient cohort in whom we performed liposuction to superficialize viable but deep vascular accesses. Out of 14 patients, 12 had arteriovenous fistulas and 2 arteriovenous grafts. The primary end points were the ability to superficialize a completely unusable access and to remove the hemodialysis catheter (3patients), or to significantly extend the useful length of a deep access in which only a very short segment was used and to continue to use the access post-surgery without the need to place a dialysis catheter (11 patients).

RESULTS

The study goal was met in 13 out of 14 patients. In two of three patients, the catheters were removed and their access usable length was 14 and 13 cm, respectively. The accesses could be used immediately after liposuction in all patients in which this applied-11 patients. The usable access length increased from a mean of 5 to 12.7 cm. The access mean depth decreased from 10.8 mm pre-surgery to 7 mm post-surgery and 5.3 mm 4 weeks after surgery. The mean volume of fat removed was 43.8 cc. We had only one surgical complication: bleeding that was readily controlled with manual pressure. All patients were discharged to home the same day. Postoperative pain was mild.

CONCLUSION

Liposuction is effective, safe, and seems to be the least invasive technique of superficialization.

Safety and efficacy of the Tablo hemodialysis system for in-center and home hemodialysis

Introduction: Home hemodialysis remains underutilized despite observational data indicating more favorable outcomes with home compared with in‐center hemodialysis. The Tablo Hemodialysis system is designed to be easy to learn and use and to facilitate adoption of home hemodialysis. The objective of the current investigational device exemption (IDE) study was to evaluate the safety and efficacy of Tablo managed in‐center by health care professionals and in‐home by patients and/or caregivers.

Methods: A prospective, multicenter, open‐label, crossover trial comparing in‐center and in‐home hemodialysis using Tablo. There were 4 treatment periods during which hemodialysis was prescribed 4 times per week: 1‐week Run‐In, 8‐week In‐Center, 4‐week Transition, and 8‐week In‐Home. The primary efficacy endpoint was weekly standard Kt/V_urea ≥ 2.1. The secondary efficacy endpoint was delivery of ultrafiltration (UF) within 10% of prescribed UF. We collected safety and usability data.

Findings: Thirty participants enrolled and 28 completed all trial periods. Adherence to the protocol requirement of 4 treatments per week was 96% in‐center and 99% in‐home. The average prescribed and delivered session lengths were 3.4 hours for both the In‐Center and the In‐Home periods. The primary efficacy endpoint for the intention‐to‐treat cohort was achieved in 199/200 (99.5%) of measurements during the In‐Center period and 168/171 (98.3%) In‐Home. The average weekly standard Kt/V_urea was 2.8 in both periods. The secondary efficacy UF endpoint was achieved in the ITT cohort in 94% in both in‐center and in‐home. Two prespecified adverse events (AEs) occurred during the In‐Center period and 6 in the In‐Home period. None of the AEs were deemed by investigators as related to Tablo. The median resolution time of alarms was 8 seconds in‐center and 5 seconds in‐home.

Conclusion: Primary and secondary efficacy and safety endpoints were achieved during both In‐Center and In‐Home trial periods. This study confirms that Tablo is safe and effective for home hemodialysis use.

Zero balance ultrafiltration using dialysate during nationwide bicarbonate shortage: a retrospective analysis

Background

Zero balance ultrafiltration (Z-BUF) utilizing injectable 8.4% sodium bicarbonate is utilized to treat hyperkalemia and metabolic acidosis associated with cardiopulmonary bypass (CPB). The nationwide shortage of injectable 8.4% sodium bicarbonate in 2017 created a predicament for the care of cardiac surgery patients. Given the uncertainty of availability of sodium bicarbonate solutions, our center pro-actively sought a solution to the sodium bicarbonate shortage by performing Z-BUF with dialysate (Z-BUF-D) replacement fluid for patients undergoing cardiopulmonary bypass.

Methods

Single-center, retrospective observational evaluation of the first 46 patients at an academic medical center who underwent Z-BUF using dialysate over a period of 150 days with comparison of these findings to a historical group of 39 patients who underwent Z-BUF with sodium chloride (Z-BUF-S) over the preceding 150 days. The primary outcome was the change in whole blood potassium levels pre- and post-Z-BUF-D. Secondary outcomes included changes in pre- and post-Z-BUF-D serum bicarbonate levels and the amount of serum bicarbonate used in each Z-BUF cohort (Z-BUF-D and Z-BUF-S).

Results

Z-BUF-D and Z-BUF-S both significantly reduced potassium levels during CPB. However, Z-BUF-D resulted in a significantly decreased need for supplemental 8.4% sodium bicarbonate administration during CPB (52 mEq ± 48 vs. 159 mEq ± 85, P < 0.01). There were no complications directly attributed to the Z-BUF procedure.

Conclusion

Z-BUF with dialysate appears to be analternative to Z-BUF with sodium chloride with marked lower utilization of intravenous sodium bicarbonate.

Performance on the Nephrology In-Training Examination and ABIM Nephrology Certification Examination Outcomes

BACKGROUND AND OBJECTIVES

Medical specialty and subspecialty fellowship programs administer subject-specific in-training examinations to provide feedback about level of medical knowledge to fellows preparing for subsequent board certification. This study evaluated the association between the American Society of Nephrology In-Training Examination and the American Board of Internal Medicine Nephrology Certification Examination in terms of scores and passing status.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study included 1684 nephrology fellows who completed the American Society of Nephrology In-Training Examination in their second year of fellowship training between 2009 and 2014. Regression analysis examined the association between In-Training Examination and first-time Nephrology Certification Examination scores as well as passing status relative to other standardized assessments.

RESULTS

This cohort included primarily men (62%) and international medical school graduates (62%), and fellows had an average age of 32 years old at the time of first completing the Nephrology Certification Examination. An overwhelming majority (89%) passed the Nephrology Certification on their first attempt. In-Training Examination scores showed the strongest association with first-time Nephrology Certification Examination scores, accounting for approximately 50% of the total explained variance in the model. Each SD increase in In-Training Examination scores was associated with a difference of 30 U (95% confidence interval, 27 to 33) in certification performance. In-Training Examination scores also were significantly associated with passing status on the Nephrology Certification Examination on the first attempt (odds ratio, 3.46 per SD difference in the In-Training Examination; 95% confidence interval, 2.68 to 4.54). An In-Training Examination threshold of 375, approximately 1 SD below the mean, yielded a positive predictive value of 0.92 and a negative predictive value of 0.50.

CONCLUSIONS

American Society of Nephrology In-Training Examination performance is significantly associated with American Board of Internal Medicine Nephrology Certification Examination score and passing status.

IL6 plasma concentrations in patients with sepsis receiving SLED and antibiotics: a predictor for survival

BACKGROUND

The present study evaluated interleukin-6 (IL6) as a predictor of mortality in patients and sepsis with acute kidney injury (AKI) receiving sustained low-efficiency dialysis (SLED) and antibiotic therapy.

PATIENTS AND METHODS

Seven patients with sepsis receiving antibiotics and SLED for AKI were studied. Blood was obtained at baseline prior to SLED and antibiotics, during SLED, and then after stopping SLED. IL6 concentrations were measured using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Mean plasma IL6 concentrations ranged between 700 and 900 pg/ml for the first 8 h after starting SLED but was significantly lower after discontinuation of SLED (200-250 pg/ml) (p=0.0044). Three out of seven patients survived to be discharged from the hospital and all three had significantly lower concentrations of IL6 during the first 8 h compared to those who died in the hospital (p<0.0001).

CONCLUSION

The combination of SLED and antibiotic therapy was unable to lower the initial high plasma IL6 concentrations, and high initial IL6 concentrations predicted in-hospital mortality.

Calcium supplementation after parathyroidectomy in dialysis and renal transplant patients

Background

Data on the risk factors and clinical course of hungry bone syndrome are lacking in dialysis and renal transplant patients who undergo parathyroidectomy. In this study, we aimed to assess the risks and clinical course of hungry bone syndrome and calcium repletion after parathyroidectomy in dialysis and renal transplant patients.

Methods

We performed a retrospective review of parathyroidectomies performed at The Nebraska Medical Center.

Results

We identified 41 patients, ie, 30 (73%) dialysis and eleven (27%) renal transplant patients. Dialysis patients had a significantly higher pre-surgery intact parathyroid hormone (iPTH, P<0.001) and a larger iPTH drop after surgery (P<0.001) than transplant recipients. Post-surgery hypocalcemia in dialysis patients was severe and required aggressive and prolonged calcium replacement (11 g) versus a very mild hypocalcemia requiring only brief and minimal replacement (0.5 g) in transplant recipients (P<0.001). Hypophosphatemia was not detected in the dialysis group. Phosphorus did not increase immediately after surgery in transplant recipients. The hospital stay was significantly longer in dialysis patients (8.2 days) compared with transplant recipients (3.2 days, P<0.001).

Conclusion

The clinical course of hungry bone syndrome is more severe in dialysis patients than in renal transplant recipients. Young age, elevated alkaline phosphatase, elevated pre-surgery iPTH, and a large decrease in post-surgical iPTH are risk factors for severe hungry bone syndrome in dialysis patients.

How I do it: endovascular treatment of arteriovenous graft pseudoaneurysms-watch out for the mouth

We present a case of arteriovenous graft pseudoaneurysms treated endovascularly with stent grafts and make suggestions regarding the technique of evaluating the pseudoaneurysms and choosing the proper location to deploy the stent grafts to maximize the outcomes and minimize the length of the graft covered by the stent. We also comment on the selection of lesions that are suitable to be treated with this technique.

Nocturnal home hemodialysis for a patient with type 1 hyperoxaluria

Type 1 primary hyperoxaluria is a genetic disorder caused by deficiency of the liver-specific peroxisomal enzyme alanine-glyoxylate aminotransferase. This enzyme deficiency leads to excess oxalate production and deposition of calcium oxalate salts, resulting in kidney failure and systemic oxalosis. Aside from combined liver/kidney transplantation, no curative treatment exists. Various strategies for optimizing dialysis treatment have been evaluated, but neither conventional hemodialysis nor peritoneal dialysis can keep pace with oxalate production in this patient population. In this report, we describe a patient with end-stage renal disease from type 1 primary hyperoxaluria managed with nocturnal home hemodialysis. Performing hemodialysis 8-10 hours each night with blood flow of 350 mL/min and total dialysate volume of 60 L, she has maintained pre- and postdialysis serum oxalate levels at or below the level of supersaturation. We also review published literature regarding oxalate removal in various modalities of dialysis in patients with type 1 primary hyperoxaluria. In our patient, nocturnal hemodialysis has controlled serum oxalate levels better than conventional hemodialysis therapies. Home nocturnal hemodialysis should be considered an option for management of patients with end-stage renal disease from type 1 hyperoxaluria who are awaiting transplantation.

Development, implementation, and results of the ASN in-training examination for fellows

The American Society of Nephrology and the fellowship training program directors in conjunction with the National Board of Medical Examiners developed a comprehensive assessment of medical knowledge for nephrology fellows in-training. This in-training examination (ITE) consisted of 150 multiple-choice items covering 11 broad content areas in a blueprint similar to the American Board of Internal Medicine certifying examination for nephrology. Questions consisted of case vignettes to simulate real-life clinical experience. The first examination was given in April 2009 to 682 fellows and six training program directors. Examinees felt that the examination was well structured and relevant to their training experience Longitudinal performance on the examination will be helpful in allowing training programs to utilize results from content areas in identifying deficits in medical knowledge as well as assessing the results of any curriculum changes.

Obesity and Hemodialysis Vascular Access Failure

A variety of factors have been proposed to explain arteriovenous fistula primary failures in patients undergoing hemodialysis, including obesity, diabetes mellitus, female sex, and the absence of preoperative vein mapping. In this report, we describe 2 women for whom premature upper-extremity arteriovenous fistula failures occurred in the setting of venographic evidence of soft-tissue compression of the venous outflow with the patient's arm in the adducted position. In each instance, preoperative noninvasive duplex vein mapping showed veins of adequate diameter (0.28 to 0.54 cm), and further evaluation showed no evidence of a hypercoagulable state. Upper-extremity venography was used to assess central venous patency and fully assess the venous vasculature. Unlike the widely patent venous systems seen in the abducted position, venography performed with the upper extremities in adduction showed marked narrowing of the brachial and/or axillary veins. The hemodynamic effects of this narrowing were readily apparent in patient 2 with the appearance of collateral filling of the cephalic vein in the adducted position. Patient 1 had a body mass index of 39 kg/m(2), and patient 2 had a body mass index of 34 kg/m(2). Each patient had excess axillary soft tissue that appeared to compress the venous outflow in adduction. To our knowledge, this is the first report to radiographically document soft-tissue compression of the venous outflow of the upper extremity in the adducted position, suggesting a mechanism whereby obesity, or at least excess axillary fat, can lead to premature hemodialysis vascular access failures.

Requirements for T lymphocyte migration in explanted lymph nodes

Although the requirements for T lymphocyte homing to lymph nodes (LNs) are well studied, much less is known about the requirements for T lymphocyte locomotion within LNs. Imaging of murine T lymphocyte migration in explanted LNs using two-photon laser-scanning fluorescence microscopy provides an opportunity to systematically study these requirements. We have developed a closed system for imaging an intact LN with controlled temperature, oxygenation, and perfusion rate. Naive T lymphocyte locomotion in the deep paracortex of the LN required a perfusion rate of >13 microm/s and a partial pressure of O(2) (pO(2)) of >7.4%. Naive T lymphocyte locomotion in the subcapsular region was 38% slower and had higher turning angles and arrest coefficients than naive T lymphocytes in the deep paracortex. T lymphocyte activation decreased the requirement for pO(2), but also decreased the speed of locomotion in the deep paracortex. Although CCR7(-/-) naive T cells displayed a small reduction in locomotion, systemic treatment with pertussis toxin reduced naive T lymphocyte speed by 59%, indicating a contribution of Galpha(i)-mediated signaling, but involvement of other G protein-coupled receptors besides CCR7. Receptor knockouts or pharmacological inhibition in the adenosine, PG/lipoxygenase, lysophosphatidylcholine, and sphingosine-1-phosphate pathways did not individually alter naive T cell migration. These data implicate pO(2), tissue architecture, and G-protein coupled receptor signaling in regulation of naive T lymphocyte migration in explanted LNs.

Postinfectious glomerulonephritis in renal allograft recipients

Postinfectious glomerulonephritis (PIGN) is a rare etiology of de novo glomerulonephritis following kidney transplantation. To date, there have only been eight cases reported in the literature. We report an additional three patients transplanted at our institution between January 2000 and October 2004 who had clinical and pathologic findings consistent with posttransplant PIGN. All three patients were type 1 diabetics. One had received a cadaveric kidney transplant, one a simultaneous kidney-pancreas transplant, and the third a living related kidney transplant followed by a pancreas transplant. All patients were on triple immunosuppressive therapy with tacrolimus, mycophenolate mofetil, and prednisone. In each case, an acute decline in allograft function developed in association with a known or suspected infectious process, and renal biopsies revealed an immune complex glomerulonephritis with features of PIGN. All regained renal function with treatment of their known or suspected infections and without specific therapies for their glomerulonephritis, including corticosteroids.

Role of thromboxane A2 in the induction of apoptosis of immature thymocytes by lipopolysaccharide

Lipopolysaccharide (LPS) causes apoptotic deletion of CD4(+) CD8(+) thymocytes, a phenomenon that has been linked to immune dysfunction and poor survival during sepsis. Given the abundance of thromboxane-prostanoid (TP) receptors in CD4(+) CD8(+) thymocytes and in vitro evidence that thromboxane A(2) (TXA(2)) causes apoptosis of these cells, we tested whether enhanced generation of TXA(2) plays a role in LPS-induced thymocyte apoptosis. Mice injected with 50 micro LPS intraperitoneally displayed a marked increase in generation of TXA(2) and prostaglandin E(2) in the thymus as well as apoptotic deletion of CD4(+) CD8(+) thymocytes. Administration of indomethacin or rofecoxib inhibited prostanoid synthesis but did not affect thymocyte death. In contrast, thymocyte apoptosis in response to LPS was significantly attenuated in TP-deficient mice. These studies indicate that TXA(2) mediates a portion of apoptotic thymocyte death caused by LPS. The absence of an effect of global inhibition of prostanoid synthesis suggests a complex role for prostanoids in this model.

Risk factors for BK polyomavirus nephritis in renal allograft recipients1

Recurrent episodes of acute rejection (AR) and/or the intense immunosuppression used for their treatment have been proposed as risk factors for BK nephritis (BKN; BK refers to the initials of the first patient from whom this polyomavirus was isolated). To further examine the relationship between AR and BKN, we analyzed all kidney transplants performed at our center between January 1999 and August 2001 (n = 286). After a mean follow-up of 737 +/- 22 d, we identified nine cases of BKN (3.1%). The mean time to diagnosis of BKN was 326 +/- 56 d. No patient with BKN had a prior history of AR. During the same period, 62 patients were diagnosed with AR (22%). The mean time to diagnosis of AR was 197 +/- 40 d (p = 0.01 vs. time to diagnosis of BKN). Despite aggressive therapy with methylprednisolone and, in some cases, anti-lymphocyte antibody, none of these patients with AR developed BKN. We compared the baseline characteristics of patients in both groups and found that BKN patients were more likely to be white people (78 vs. 44%, p = 0.05) and male (89 vs. 53%, p = 0.04). Moreover, the mean tacrolimus (TAC) levels before diagnosis were higher in BKN than in AR patients (11.7 +/- 0.5 vs. 6.5 +/- 0.6 ng/mL, p < 0.001). In summary, our study shows that BKN often occurs in the absence of prior episodes of AR. In addition, our findings suggest that white males exposed to higher TAC levels are at greater risk of developing BKN.

Effector mechanisms in transplant rejection

Antigens, provided by the allograft, trigger the activation and proliferation of allospecific T cells. As a consequence of this response, effector elements are generated that mediate graft injury and are responsible for the clinical manifestations of allograft rejection. Donor-specific CD8+ cytotoxic T lymphocytes play a major role in this process. Likewise, CD4+ T cells mediate delayed-type hypersensitivity responses via the production of soluble mediators that function to further activate and guide immune cells to the site of injury. In addition, these mediators may directly alter graft function by modulating vascular tone and permeability or by promoting platelet aggregation. Allospecific CD4+ T cells also promote B-cell maturation and differentiation into antibody-secreting plasma cells via CD40-CD40 ligand interactions. Alloantibodies that are produced by these B cells exert most of their detrimental effects on the graft by activating the complement cascade. Alternatively, antibodies can bind Fc receptors on natural killer cells or macrophages and cause target cell lysis via antibody-dependent cell-mediated cytotoxicity. In this review, we discuss these major effector pathways, focusing on their role in the pathogenesis of allograft rejection.

Eicosanoids: lipid mediators of inflammation in transplantation

Eicosanoids are a family of lipid mediators derived from the metabolism of arachidonic acid. Eicosanoids, such as prostanoids and leukotrienes, have a wide range of biological actions including potent effects on inflammation and immunity. It has been almost 20 years since the first reports emerged suggesting a role for eicosanoids in transplantation. Since then, a number of functions have been ascribed to these mediators, ranging from immunomodulation to regulation of allograft hemodynamics. In this review, we will highlight the effects of eicosanoids in transplantation, focusing particularly on evidence provided by gene targeting studies. In the future, pharmacological manipulation of eicosanoids and their receptors may provide a novel approach for controlling inflammation and promoting allograft acceptance.

Hypoxanthine-guanine phosphoribosyltransferase (HPRT) expression in the central nervous system of HPRT-deficient mice following adenoviral-mediated gene transfer

In this study we show that recombinant adenovirus can augment hypoxanthine-guanine phosphoribosyltransferase (HPRT) levels in the central nervous system (CNS) of HPRT-deficient mice. Recombinant adenovirus containing the cDNA for rat HPRT (rHPRT) expressed from the Rous sarcoma virus LTR (RSV LTR) was constructed (AdRSVrHPRT). AdRSVrHPRT was injected into the right caudate nucleus of 7-week-old HPRT-deficient mice. Brains were analyzed for gene transfer, transgene expression and function by DNA PCR, in situ RNA hybridization, and enzyme bioactivity. The results show that rHPRT cDNA delivered by an adenoviral vector can augment HPRT levels in brain tissue and documents the utility of gene transfer to restore HPRT activity in an HPRT-deficient CNS.