B-cell depletion extends the survival of GTKO.hCD46Tg pig heart xenografts in baboons for up to 8 months.

Xenotransplantation of genetically modified pig organs offers great potential to address the shortage of human organs for allotransplantation. Rejection in Gal knockout (GTKO) pigs due to elicited non-Gal antibody response required further genetic modifications of donor pigs and better control of the B-cell response to xenoantigens. We report significant prolongation of heterotopic alpha Galactosyl transferase "knock-out" and human CD46 transgenic (GTKO.hCD46Tg) pig cardiac xenografts survival in specific pathogen free baboons. Peritransplant B-cell depletion using 4 weekly doses of anti-CD20 antibody in the context of an established ATG, anti-CD154 and MMF-based immunosuppressive regimen prolonged GTKO.hCD46Tg graft survival for up to 236 days (n = 9, median survival 71 days and mean survival 94 days). B-cell depletion persisted for over 2 months, and elicited anti-non-Gal antibody production remained suppressed for the duration of graft follow-up. This result identifies a critical role for B cells in the mechanisms of elicited anti-non-Gal antibody and delayed xenograft rejection. Model-related morbidity due to variety of causes was seen in these experiments, suggesting that further therapeutic interventions, including candidate genetic modifications of donor pigs, may be necessary to reduce late morbidity in this model to a clinically manageable level.

Left ventricular pressure measurement by telemetry is an effective means to evaluate transplanted heart function in experimental heterotopic cardiac xenotransplantation.

Evaluation of the function of heterotopic cardiac transplants has traditionally been accomplished by either manual palpation or serial biopsies. Both methods have drawbacks. Palpation can be difficult to differentiate a pulse from the graft versus a transmitted pulse from the native aorta. Serial biopsies, though accurate, require multiple laparotomies, leading to increased morbidity and possibly mortality rates. In this study we used an advanced telemetry system, consisting of an intra-abdominal implant, that was capable of continuously monitoring simultaneously several parameters of the transplanted heart and the status of the recipient. In a large animal model of heterotopic cardiac xenotransplantation (pig donor to baboon recipient), we implanted the device in 12 animals: 8 with and 4 without immunosuppression. We monitored and continuously recorded the left ventricular pressure (both peak-systolic and end-diastolic [LVEDP]), heart rate, and the electrocardiogram pattern of the transplanted heart as well as the temperature of the recipient. The left ventricular pressure proved to be the most valuable parameter to assess graft heart function. In the 4 nonimmunosuppressed cases, grafts were rejected acutely. In these cases, the end-diastolic pressure increased sharply and the heart stopped contracting when the difference between the systolic and the diastolic pressure decreased to <10 mm Hg. The earliest reproducible sign of rejection was an increased LVEDP. Among long-term survivors, the increase in diastolic pressure was gradual, indicating progressive thickening of the myocardium and decreased compliance of the ventricle. Six of 8 immunosuppressed animals died of other complications before rejecting the transplanted heart. The telemetry was also helpful to indicate early onset of fever in the recipients, thus allowing us to intervene early and prevent potentially lethal septic complications. Continuous monitoring of several parameters via telemetry allowed detection of changes associated with rejection as well as other complications at an early stage, allowing prompt intervention, treatment, and possibly reversal of rejection.

Surgical and nonsurgical complications of a pig to baboon heterotopic heart transplantation model.

A modified immunosuppressive regimen, developed at the National Institutes of Health, has been employed in a large animal model of heterotopic cardiac xenotransplantation. Graft survival has been prolonged, but despite this, our recipients have succumbed to various surgical or nonsurgical complications. Herein, we have described different complications and management strategies. The most common complication was hypercoagulability (HC) after transplantation, causing thrombosis of both small and large vasculature, ultimately leading to graft loss. While managing this complication we discovered that there was a delicate balance between HC and consumptive coagulopathy (CC). CC encountered in some recipient baboons was not able to be reversed by stopping anticoagulation and administering multiple blood transfusions. Some complications had iatrogenic components. To monitor the animals, a solid state left ventricular telemetry probe was placed directly into the transplanted heart via the apex. Induction of hypocoagulable states by continuous heparin infusion led to uncontrollable intra-abdominal bleeding in 1 baboon from this apical site. This occurrence necessitated securing the probe more tightly with multiple purse strings and 4-quadrant pledgeted stay sutures. One instance of cardiac rupture originated from a lateral wall infarction site. Earlier studies have shown infections to be uniformly fatal in this transplant model. However, owing to the telemetry placement, infections were identified early by temperature spikes that were treated promptly with antibiotics. We had several cases of wound dehiscence due to recipients disrupting the suture line. These complications were promptly resolved by either re-approximating the wound or finding distractions for the baboon. A few of the most common problems we faced in our earlier experiments were related to the jacket, tether, and infusion pumps. It was difficult to keep the jackets on some baboons and the tether had to be modified several times before we assured long-term success. Infusion catheter replacement resulted in transplant heart venous obstruction and thrombosis from a right common femoral venous line. Homeostatic perturbations such as HC and CC and baboon-induced wound complications comprised most complications. Major bleeding and death due to telemetry implantation and infarct rupture occurred in 2 baboons. Despite the variety of complications, we achieved significant graft prolongation in this model.

Spirometry in surgery for anterior mediastinal masses.

STUDY OBJECTIVES: To identify the impact of upright and supine spirometry (USS) on the choice of anesthesia and outcomes in patients undergoing surgery for anterior mediastinal masses (AMMs). DESIGN: Retrospective cohort study. SETTING: A referral, tertiary-care, military medical center. PATIENTS: We reviewed the records of all patients who underwent surgery for AMMs between June 1994 and December 2000 at Walter Reed Army Medical Center. Patients aged > or = 18 years who had "anterior mediastinal mass" listed as the preoperative diagnosis, which had been confirmed by a preoperative CT scan, and who had available preoperative spirometry data were included in our analysis. In cases in which surgery was performed more than once on the same individual, only data from the first operation were evaluated. MEASUREMENTS: Patient demographics, the results of pulmonary function testing, perioperative complications, type of anesthesia, type of surgery, and pathology were used in the evaluation. RESULTS: Thirty-seven patients (median age, 31 years; age range, 19 to 86 years) were included in the final analysis. There were 24 men and 13 women in this group. The mean (+/- SD) seated FVC and FEV(1) values for the group were 4.02 +/- 0.75 L (90.7 +/- 13.3% predicted) and 3.22 +/- 0.56 L 89.6 +/- 14.2% predicted. Twelve patients (32.4%) had USS ordered, and 10 patients (27.0%) had USS performed. USS was ordered significantly more frequently in younger and symptomatic patients (p = 0.022 and p = 0.005, respectively). Spirometry suggestive of possible upper airway obstruction was found in four patients. However, general anesthesia was used in all four patients without complications. Only two patients suffered perioperative complications. One of these patients had normal USS values but underwent surgery under local anesthesia nonetheless. CONCLUSIONS: The recommendation to perform USS prior to surgery on AMMs is based on anecdotal data. Our study found that the incidence of perioperative complications in surgery for AMMs is low. We also found that USS is not ordered in all patients preoperatively and that the results do not always alter the anesthetic technique when abnormal. One patient who experienced a perioperative complication had normal USS values. Larger studies are necessary to further evaluate the utility of USS in surgery for AMMs.

Impact of revised stage classification of lung cancer on survival: a military experience.

STUDY OBJECTIVES: This report reviews results of surgical management of lung cancer at a military medical center using the revised 1997 stage classification and determines the impact of the revised system on survival rates. It also compares our results with the recent reports from Japan and from a large, multinational study involving several institutions. DESIGN: Retrospective review. SETTING: Department of Cardiothoracic Surgery, Walter Reed Army Medical Center (WRAMC), Washington, DC. PATIENTS OR PARTICIPANTS: Active military members, their dependents, and eligible retired military members who were admitted to WRAMC for surgical treatment of lung cancer between January 1984 and December 1996. METHODS: Records of all patients who had surgical resection with intent to cure were reviewed. Data extracted included clinical and pathologic stages according to the 1997 revised stage classification. Survival probabilities for the stages were calculated by the Kaplan-Meier actuarial method. The log rank test was used to compare survival rates between stages and stage subsets. A p value < 0.05 was considered statistically significant. MEASUREMENTS AND RESULTS: Five hundred fifty-two of the 1,398 patients with primary lung cancers underwent curative surgical resection (39.5%). The operative mortality was 2%. Using the revised 1997 stage classification, the survival rate for stage IA was 77%; IB, 62%; IIA, 57%; IIB, 47%; IIIA, 28%; IIIB, 20%; and IV, 0%. The overall actuarial 5-year and 10-year survival rates were 58% and 45%, respectively (median survival, 3.3 years; mean survival 3.9+/-0.1 years). CONCLUSIONS: Our results confirm the justification for the recent revisions in the staging system of lung cancer; however, there are still discrepancies that cannot be explained.

Reduction of conjugated dienes in lung transplantation: effect of BN 52021.

Oxygen-derived free radicals have been identified as the mediators of tissue injury during reperfusion in organ transplantation. Lipid peroxidation of cell membrane polyunsaturated fatty acids, generating conjugated dienes (CD), is a toxicity of oxygen-derived free radicals. The CD structure in fatty acyl moieties was measured by high-pressure liquid chromatography in samples of inferior pulmonary venous blood and pulmonary tissue to assess reperfusion injury and oxygen-derived free radical-mediated damage in a canine model of left lung allotransplantation. The cold ischemic preservation interval was 6 hours and the posttransplantation monitoring period was 6 hours. Twenty-eight size- and weight-matched adult male dogs underwent left lung allotransplantation and were randomized to receive pulmonary artery flush of modified Euro-Collins (EC) (40 mL/kg) or University of Wisconsin (UW) (40 mL/kg) solutions alone or with the addition of the platelet-activating factor antagonist BN 52021 (10 mg/kg). When employed, BN 52021 was administered to donors 30 minutes before harvest and recipients 30 minutes before reperfusion. Left and right inferior pulmonary venous blood samples were obtained at baseline before transplantation and at 1, 2, 4, and 6 hours after transplantation; tissue samples were obtained after euthanasia. Serum and tissue CD levels are expressed as mean fraction of the total hydroperoxide sample +/- standard error of the mean. At 6 hours after transplantation, the EC group's (n = 7) CD fraction was 0.28 +/- 0.03, whereas that of the EC + BN 52021 group (n = 7) was 0.12 +/- 0.03 (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Resection for esophageal carcinoma at a Virginia hospital 1981-1989.

Between January 1, 1981 and December 31, 1989, 222 patients with carcinoma of the esophagus were seen at Fairfax Hospital. Fifty-eight (26.1%) underwent esophagogastrectomy. Operative (30-day) mortality was 8.6%. Follow-up was 98.3% complete. Of hospital survivors, 38 (76%) were resected for potential cure versus 12 (24%) for palliation. Consistent with the experience of others, a minority of patients (26%) presented with early (Stage I & II) disease; forty patients (69%) were noted to be Stage III or IV at time of resection and three patients (5%) were stage indeterminant. The five year Kaplan-Meier product limit survival estimate for Stage II patients was 52%, versus 22% for stage III, and 0% for Stage IV.

Platelet activating factor antagonist enhances lung preservation in a canine model of single lung allotransplantation.

Optimal techniques for lung preservation are yet to be defined. Platelet activating factor is a phospholipid released by a variety of cells and produces pulmonary abnormalities similar to posttransplantation pulmonary dysfunction. We investigated the strength of the effect of the platelet activating factor antagonist BN 52021 as compared with that of deferoxamine, an iron chelator previously shown to improve lung preservation. Differential lung function and pulmonary hemodynamics were used to assess preservation after a 6-hour period of cold ischemic storage in a modified canine model of left lung allotransplantation. Thirty size- and weight-matched mongrel male dogs were used for 15 transplant procedures randomized to one of three preservation techniques. The University of Wisconsin solution was used as the basic flush solution for all experimental animals. BN 52021 was added to the flush solution in one group (10 mg/kg, n = 5) and deferoxime in another group (10 mg/kg, n = 5). No additives were used for the control animals (n = 5). BN 52021 and deferoxime were administered to respective donor animals 30 minutes before organ harvesting (10 mg/kg) and to recipient animals 30 minutes before reperfusion (10 mg/kg). The pulmonary artery flush solution was administered (40 ml/kg) over 4 minutes. Recipient animals received double-lumen endotracheal tubes and were monitored with balloon-tipped, flow-directed catheters in both pulmonary arteries and dual-angle ultrasonic flow probes around each pulmonary artery. Solid-state high-fidelity micromanometers were used to measure pressures in the pulmonary artery, the left atrium, and the left ventricle. Systemic arterial, right and left pulmonary venous, and mixed venous blood samples were analyzed at 1, 2, 4, and 6 hours after transplantation. Pulmonary venous oxygen tension of the transplanted lung for the control group was 202 +/- 81 mm Hg versus 282 +/- 53 mm Hg for the BN 52021 group 6 hours after transplantation (p less than 0.05). Pulmonary vascular resistance of the transplanted lung for the control group was 319 +/- 54 dynes.sec.cm-5 versus 149 +/- 71 dynes.sec.cm-5 for the BN 52021 group (p less than 0.05). Proton magnetic resonance spectroscopy was performed on segments of upper and lower lobes of the native and transplanted lung from recipient animals to determine total lung water content. The BN 52021 group had a total lung water content of 57.3% as compared with 51.9% for the deferoxime group (p = not significant) and 88.6% for the control group (p less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Platelet activating factor antagonist enhances lung preservation.

Platelet activating factor (PAF) is a potent phospholipid mediator of the immune and inflammatory responses, which causes physiologic effects similar to post-transplant pulmonary dysfunction. This study investigates the hypothesis that the use of a specific PAF antagonist (PAFA), BN 52021, in canine lung transplantation improves lung preservation. Twelve pairs of canines underwent left lung allotransplantation after pulmonary artery flushing with modified Euro-Collins (EC) solution (40 ml/kg). The experimental group (N = 6) received EC with BN 52021 (10 mg/kg). BN 52021 was administered to donors prior to harvest and to recipients prior to reperfusion. The preservation interval was 20 hr and the study period was 12 hr post-transplant. Differential pulmonary function and hemodynamics were monitored, comparing the transplanted left lung and the native right lung. Recipients were ventilated on 100% O2. Administration of the platelet activating factor antagonist, BN 52021, was associated with improvement in transplant lung oxygenation, pulmonary vascular resistance, and compliance. At 12 hr, transplant lung pulmonary venous oxygen tension in the treatment group (EC + BN 52021) was 154 +/- 21 mm Hg versus 87 +/- 10 mm Hg in the control group (EC) (P less than 0.05). Pulmonary vascular resistance of the transplant lung at 12 hr was 146 +/- 24 Dynes.sec.cm-5 in the EC + BN 52021 group as compared to 320 +/- 51 Dynes.sec.cm-5 in the EC group (P less than 0.05). Dynamic pulmonary compliance of the transplant lung at 12 hr was 32 +/- 2.9 ml/cm H2O in the EC + BN 52021 group versus 13 +/- 2.0 ml/cm H2O in the EC group (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Donor heart valves: electron microscopic and morphometric assessment of cellular injury induced by warm ischemia.

Cryopreserved allograft valves are increasingly being used as valvular replacements. Leaflet fibroblast viability has been suggested to influence clinical durability. The warm ischemic time is thought to be a critical determinant of this cell viability. The purpose of this study was to apply quantitative morphometric methods to characterize, by transmission electron microscopy, valvular cellular injury resulting from progressive warm ischemic time. Porcine aortic valves were harvested with a spectrum of warm ischemic times (40 minutes and 2, 6, 12, 24, and 36 hours; five valves per warm ischemic time; n = 30) and processed by standard electron microscopic methods. To ensure randomized tissue selection within each warm ischemic time interval, we randomly selected one thin section from each leaflet. The first ten cells in each thin section were photographed and cellular injury was assessed (cell disruption, dilation of endoplasmic reticulum, cytoplasmic edema, nuclear and mitochondrial changes). Nine hundred micrographs have been analyzed by Cochran-Mantel-Haenszel statistics to determine if a significant association between warm ischemic time and cellular injury exists. Our findings indicate a significant association between reversible cell injury through 24 hours of warm ischemic injury (p less than 0.0001). Furthermore, a significant association between irreversible cell injury and progressive warm ischemia through 36 hours was also found. These findings indicate that the ischemic interval after donor death is associated with progressive leaflet cell injury. Cellular damage begins shortly after donor death and continues incrementally throughout 36 hours. After 2 hours of warm ischemic injury 37% of the cells had morphologic evidence of injury. After 6 hours of warm ischemic injury the number of injured cells increased to 73%. By 36 hours 22% of the cells appeared normal. Irreversible cell injury increases with prolonged ischemia and becomes quantitatively impressive at 24 hours, by which time 26% of cells are so affected. Conversely, some cells are resistant to irreversible injury for a prolonged ischemic interval.

Ross' first homograft replacement of the aortic valve.

Ross' first homograft replacement of the aortic valve was reported in 1962. The homograft has been in continuous use around the world ever since. Much has been learned about how to handle homografts, both before and during their implantation. Homografts have special advantages, which make them an appropriate choice in a number of settings. This first successful case by Donald Ross set the stage for the growth in homograft valve use and the subsequent development of many ways of using allograft cardiovascular tissue for optimal cardiac reconstructions.