Morbidity and mortality after neoadjuvant therapy for lung cancer: the risks of right pneumonectomy.

BACKGROUND: The risks of complications in patients undergoing thoracotomy after neoadjuvant therapy for nonsmall cell lung cancer remain controversial. We reviewed our experience to define it further. METHODS: All patients undergoing thoracotomy after induction chemotherapy from 1993 through 1999 were reviewed. Univariate and multivariate methods for logistic regression model were used to identify predictors of adverse events. RESULTS: Induction chemotherapy included mitomycin, vinblastine, and cisplatin (179 patients), carboplatin and paclitaxel (152 patients), and other combinations (139 patients). Eighty-five patients (18%) received preoperative radiation. Operations were pneumonectomy (97 patients), lobectomy (297 patients), lesser resection (18 patients), and exploration only (58 patients). Total mortality was 7 of 297 (2.4%) and 11 of 97 (11.3%) for all lobectomies and pneumonectomies, respectively, but mortality was 11 of 46 (23.9%) for right pneumonectomy. Complications developed in 179 patients (38%). By multiple regression analysis, right pneumonectomy (p = 0.02), blood loss (p = 0.01), and forced expiratory volume in one second (percent predicted) (p = 0.01) predicted complications. No factor emerged to explain this high right pneumonectomy mortality rate. CONCLUSIONS: Pulmonary resection after neoadjuvant therapy is associated with acceptable overall morbidity and mortality. However, right pneumonectomy is associated with a significantly increased risk and should be performed only in selected patients.

Toxicity and pharmacokinetics of isolated lung perfusion with cisplatin in rat.

OBJECTIVE: This study was designed to evaluate the toxicity and the pharmacokinetics of cisplatin administered via isolated lung perfusion in Fischer 344 rat. METHODS: Toxicity study; Cisplatin dosages of 3.3, 5.0, 6.7, and 10.0 mg/kg were injected intravenously in four groups, respectively. Cisplatin dosages of 3.3, 5.0, and 6.7 mg/kg were perfused via isolated lung perfusion in a further three groups, respectively. The maximum tolerated dosage of cisplatin was determined by assessing the survival rate on day 21. Pharmacokinetics study; Animals received 6.7 mg/kg of cisplatin intravenously or 3.3 mg/kg of cisplatin via isolated lung perfusion. The cisplatin levels of the lung were measured by flameless atomic spectrometry. RESULTS: Toxicity study; The maximum tolerated dosage of cisplatin via intravenous injection was 6.7 mg/kg, and via isolated lung perfusion was 3.3 mg/kg. Pharmacokinetics study; The cisplatin level in the perfused lung was significantly higher than that in the lung of the animal treated intravenously (16.6 +/- 6.2 micrograms/g of tissue and 7.5 +/- 3.2 micrograms/g of tissue, respectively) (p = 0.0096). CONCLUSION: Isolated lung perfusion with 3.3 mg/kg of cisplatin was pharmacokinetically superior to the maximum tolerated intravenous injection of cisplatin.

Isolated lung perfusion for patients with unresectable metastases from sarcoma: a phase I trial.

BACKGROUND: In patients with unresectable pulmonary metastases from sarcoma, systemic chemotherapy has had limited efficacy possibly because of dose-limiting toxicities. Isolated lung perfusion is an alternative method of delivering high-dose chemotherapy to the lungs while minimizing systemic toxicities. We present the results of our Phase I trial of isolated lung perfusion with doxorubicin hydrochloride in such a group of patients. METHODS: From May 1995 to June 1997, 8 patients with unresectable metastases from sarcoma limited to the lungs underwent isolated lung perfusion with doxorubicin. A dose-escalation schedule starting at 40 mg/m2 was used. Seven patients were treated with a dose of 40 mg/m2 or less, and 1 patient received 80 mg/m2. Blood, tumor, and normal lung samples were obtained at various time points during the operation. Patients were evaluated for cardiac, pulmonary, and other toxicities. RESULTS: The doxorubicin concentrations in both normal lung and tumor correlated directly with the amount of doxorubicin in the perfusate. The tumors took up less doxorubicin than the lung. All patients had minimal or undetectable systemic levels of doxorubicin at the conclusion of the perfusion. There were no cardiac or other systemic toxicities. In the 7 patients perfused with 40 mg/m2 or less of doxorubicin, there was a significant decrease in the forced expiratory volume in 1 second and a trend toward a significant decrease in diffusing capacity. The patient who received 80 mg/m2 underwent lung scanning postoperatively, and scans showed no ventilation or perfusion in the perfused lung. There were no perioperative deaths. Two patients are alive with disease, and 6 patients died of disease. The median follow-up is 11 months and the longest, 31 months. There were no partial or complete responses. One patient had stabilization of disease in the perfused lung, whereas the lesions in the untreated lung progressed markedly. CONCLUSION: Isolated lung perfusion is well tolerated by patients and effectively delivers high doses of doxorubicin to the lung and tumor tissues while minimizing systemic toxicities. A single dose of 80 mg/m2 resulted in substantial injury to the lung. There were no partial or complete responses in patients perfused with doxorubicin at the maximum tolerated dose of 40 mg/m2. Isolated lung perfusion remains a model for testing new and innovative therapies for metastatic sarcoma.

Rapid activation of MDR1 gene expression in human metastatic sarcoma after in vivo exposure to doxorubicin.

Overexpression of P-glycoprotein (Pgp), a multidrug transporter encoded by the MDR1 gene, is associated with chemoresistance in some human solid tumor malignancies. To date, analyses of MDR1 levels in solid tumors have examined constitutive increases in expression at relapse. In the present study, we have evaluated the acute induction of MDR1 gene expression in a solid human tumor as a function of time in response to in vivo exposure to chemotherapy. Five patients with unresectable sarcoma pulmonary metastases underwent isolated single lung perfusion with doxorubicin. Relative MDR1 gene expression was measured in metastatic tumor nodules and normal lung specimens after initiation of chemoperfusion. In four of five patients, a 3-15-fold (median, 6.8) increase in MDR1 RNA levels was detected in tumors at 50 min after administration of doxorubicin. In contrast, normal lung samples had very low levels of MDR1 RNA prior to perfusion, and no acute increases were observed after therapy. These findings demonstrate, for the first time, that MDR1 gene expression can be rapidly activated in human tumors after transient in vivo exposure to cytotoxic chemotherapy.

Thoracic surgical spectrum of HIV infection.

The thoracic surgeon is often called on to diagnose or treat a variety of disorders associated with human immunodeficiency virus (HIV) infection. Surgical mediastinal exploration through cervical and anterior approaches is a safe and valuable modality in appropriately selected patients with unexplained mediastinal lymphadenopathy. Open lung biopsy is used in a small subset of HIV-infected patients with undiagnosed diffuse or multifocal pulmonary disease, with an anticipated diagnostic yield of more than 70%. The biopsy can be performed either thoracoscopically or via thoracotomy, based on the expertise and discretion of the surgeon. Open lung biopsy should be used very selectively and in patients with bronchoscopically confirmed diagnoses who are failing optimal medical therapy, because the impact on outcome is minuscule and because open lung biopsy is best avoided altogether in patients with established respiratory failure. Patients with acquired immune deficiency syndrome (AIDS) have an increased incidence of pneumothorax, often associated with Pneumocystis carinii pneumonia. Depending on the clinical scenario, tube thoracostomy, pleurodesis, or pleurectomy may be used. Thoracic empyema in AIDS patients requires urgent intercostal drainage and close clinical surveillance to discern the need for decortication or rib resection and open drainage. A surgical approach to pyogenic lung abscess or invasive aspergillosis is occasionally useful. Although it is controversial whether the incidence of lung cancer is increased in patients with HIV infection, HIV-positive patients with early stage nonsmall-cell lung cancer who are otherwise surgical candidates should undergo resection, especially in the era of highly active antiretroviral therapy.

Prolonged air leak following radical upper lobectomy: an analysis of incidence and possible risk factors.

STUDY OBJECTIVES: To examine the incidence and clinical significance of prolonged air leak (PAL) in patients undergoing radical upper lobectomy and to determine potential risk factors for PAL in this group of patients. DESIGN: Retrospective review of a prospective database. SETTING: Experience of one thoracic surgeon at a tertiary care cancer center. PATIENTS: One hundred consecutive patients undergoing right upper lobectomy and mediastinal lymph node dissection for non-small cell lung cancer over an 11-year period. MEASUREMENTS: PAL was defined as an air leak lasting >7 days. Preoperative, intraoperative, and postoperative clinical data were collected and analyzed to determine the factors associated with PAL. RESULTS: PAL was the most prevalent postoperative complication, comprising 25.5% of all complications seen, and lasting an average of 12.1+/-5.3 days. In 21 of the 26 patients with PAL, this complication was the only morbidity identified. There was no statistically significant difference in patient age, gender, preoperative FEV1 and diffusion of carbon monoxide, exposure to neoadjuvant chemotherapy, status of pulmonary fissures, or pathologic stage between the PAL group vs the remaining 74 patients without this complication. A significantly greater proportion of patients with PAL had FEV1/FVC ratio < or =50% (6/26 vs 5/74; p=0.02). Patients with PAL had significantly longer median length of hospital stay (11 vs 7 days; p=0.0001). Moreover, PAL was the single most common reason for an extended length of hospitalization (21/58, 36% of all causes). CONCLUSION: PAL is an alarmingly common postoperative complication and is the most frequent cause of an extended length of hospital stay in patients undergoing radical upper lobectomy. Severe obstructive pulmonary disease predisposes patients to the development of this complication.

Characterization of local inflammatory response in an isolated lung perfusion model.

BACKGROUND: Current phase I trials of isolated lung perfusion for treatment of pulmonary metastases have an arbitrarily determined length of perfusion. Our objective was to examine the temporal course of the local and distant inflammatory response as a function of the length of perfusion (ischemia) and subsequent reperfusion in an equivalent animal model. METHODS: Sixty male Fischer 344 rats were randomized into four groups (n = 15). Each group underwent left isolated lung perfusion with buffered Hespan for 10, 30, 60, or 90 minutes. Subsequently, two subgroups of five animals within each group were allowed to reperfuse for 1 or 3 hours, respectively. Non-perfused right lung was used as control. At each time point, lung specimens were assayed for TNF-alpha by ELISA and histologic sections were examined. RESULTS: There was no significant difference between the left and right lung tissue levels of TNF-alpha at the termination of the ischemic period. However, on reperfusion, the left lung TNF-alpha levels increased significantly above the ischemia baseline in all groups, with a greater magnitude of rise in the groups with 60 and 90 minutes of preceding ischemia (12,757 +/- 1985 vs. 3524 +/- 494 pg/g, and 16,914 +/- 1657 vs. 6530 +/- 1104 pg/g, respectively; p < 0.05). There was no significant elevation in tissue levels of TNF-alpha in the right lung. Histologic changes consistent with early pulmonary edema were first detected at 12 hours following onset of reperfusion. CONCLUSIONS: Reperfusion following prolonged pulmonary ischemia during isolated lung perfusion results in a significant elevation of local tissue levels of TNF-alpha and may render the perfused lung vulnerable to the adverse effects of the inflammatory cascade.

Pulmonary metastasectomy for testicular germ cell tumors: a 28-year experience.

BACKGROUND: The role of surgery in patients with pulmonary metastatic germ cell tumors has been evolving since the 1970s. To evaluate the results of pulmonary resection, we reviewed our 28-year experience. METHODS: Between July 1967 and May 1995, 157 patients with testicular germ cell tumors underwent pulmonary resections for suspected metastases. Their clinical and pathological data were reviewed. Kaplan-Meier and Cox regression models were used to analyze prognostic factors for survival after resection of metastatic disease. RESULTS: All patients were male with median age of 27 years (range 15-65). Complete resection was accomplished in 155 (99%) patients. Viable carcinoma was present in 44% (70) of the patients. Forty-one (26%) patients had metastases to other sites after pulmonary metastasectomy. The overall actuarial survival 5 years after pulmonary resection was 68% for the entire group and 82% for patients diagnosed after 1985. On multivariate analysis, the adverse prognostic factors were metastases to nonpulmonary visceral sites (p = 0.0069) and the presence of viable carcinoma in the resected specimen (p < 0.0001). CONCLUSIONS: With current chemotherapy regimens, almost 85% of the patients with testicular germ cell tumors undergoing complete resection of their pulmonary metastases can be expected to achieve long-term survival.

Diagnostic and therapeutic video assisted thoracic surgery (VATS) following chest trauma.

OBJECTIVE: Thoracic injury remains a major source of morbidity and mortality in urban trauma centers. With the advent and increasing expertise in video assisted thoracic surgery, this modality has become an attractive alternative in the management of patients with thoracic injury. This report will review our experience with video assisted thoracic surgery at a level I trauma center and attempt to further delineate the indications for and timing of thoracoscopy in thoracic trauma. METHODS: We identified 16 patients who had undergone video assisted thoracic surgery following chest trauma between July 1991 and June 1994. There were 15 penetrating and one blunt trauma. All 16 patients were initially treated with tube thoracostomy. From 0-20 days post-injury, video assisted thoracic surgery was attempted with either diagnostic or therapeutic intentions. RESULTS: Twelve of the 16 patients (75%) had successful thoracoscopy. Three patients had diaphragmatic injury excluded and nine patients had successful evacuation of clotted hemothoraces. Evacuation of clotted hemothorax up to 7 days post-injury was safe and easily accomplished. Four patients (25%) had unsuccessful thoracoscopy and were converted to standard thoracotomy; failure was attributed to either suboptimal single lung ventilation or severe pleural inflammatory reaction. The only death in the entire group occurred 10 days after a thoracotomy for retained hemothorax. The median post-operative hospital stay following successful video assisted thoracic surgery was 3.5 days. CONCLUSIONS: Video assisted thoracic surgery can be utilized as an effective and safe method for the initial diagnostic evaluation and surgical management of stable patients with penetrating thoracic trauma.

Isolated lung perfusion with doxorubicin prolongs survival in a rodent model of pulmonary metastases.

BACKGROUND: We developed a rodent model of unilateral pulmonary metastases to evaluate long-term survival after isolated lung perfusion with doxorubicin. METHODS: In the model development study, on day 0, two groups of F344 rats (n = 15) underwent transient right pulmonary artery occlusion for either 5 or 10 minutes at the time of intravenous injection of methylcholantrene-induced sarcoma cells. On day 14, all animals were sacrificed and lung nodules counted. In the survival study, on day 0, 21 rats received intravenous injection of sarcoma cells with concomitant 10-minute right pulmonary artery occlusion. On day 7, eight rats underwent left isolated lung perfusion with doxorubicin (6.4 mg/kg); five rats underwent perfusion with buffered Hespan; six untreated rats were studied as controls. RESULTS: Ten of fifteen animals (67%) in the model study with 5-minute pulmonary artery occlusion had right-sided tumor nodules. Ten-minute occlusion resulted in a tumor-free right lung in all animals. In the survival study, all animals in the Hespan and control groups died of massive tumor replacement of the left lung, with median survival times of 20 and 18 days, respectively. The median survival time of 36 days for the animals undergoing isolated lung perfusion with doxorubicin was significantly longer (p < 0.00001). The left lung of two of the doxorubicin perfused rats was tumor-free at 6 weeks. CONCLUSIONS: Isolated lung perfusion with doxorubicin results in a durable response and prolongs survival in the treatment of experimental sarcoma pulmonary metastases.

Pancreatoduodenectomy for giant benign villous adenoma of the ampulla of Vater.

The case of a 36-year-old man with a villous adenoma of the duodenum is presented. His history included jaundice, pruritus, and weight loss. Physical examination was otherwise unremarkable. Laboratory data included anemia, guaiac-positive stool, hyperamylasemia, and abnormal liver function tests. Biliary ductile dilation was seen on ultrasonography; a filling defect in the duodenum was seen on CT scan, and endoscopic biopsy revealed villous adenoma with dysplasia. Pancreatoduodenectomy was performed and recovery was uneventful. Histopathology confirmed moderate dysplasia. Review of the literature reveals this to be a rare lesion (less than 1% of duodenal neoplasms). Local excision has been advocated for small, histologically proven benign, lesions. Where doubt of benignity exists, however, and in the case of "giant" tumors (>3.0 cm greatest dimension), pancreatoduodenectomy is indicated.

Sequential bilateral isolated lung perfusion in the rat: an experimental model.

BACKGROUND: A model of isolated single-lung perfusion in the rat has been established in our laboratory to study the chemotherapeutic treatment of pulmonary metastases. A sequential bilateral isolated lung perfusion model was designed to investigate the feasibility of staged perfusions in the rat. METHODS: Twenty-four Fischer rats were randomized into three experimental groups of 8 rats each. All rats underwent left isolated lung perfusion. One, 2, or 3 weeks later, the rats in groups I, II, and III, respectively, underwent contralateral (right) perfusion. Five control animals (group IV) underwent sequential bilateral sham thoracotomies 1 week apart. Arterial blood gas analysis was performed 1 week after the second operation in the rats in groups I and IV. RESULTS: All animals survived the first operation, with 100% (8/8), 75% (6/8), and 100% (8/8) of the animals in perfusion groups I, II, and III, respectively, surviving the second operation. All control animals (group IV) survived the second sham thoracotomy. Arterial blood gas analysis did not show a significant difference in the oxygen or carbon dioxide partial pressure or the pH between group I and IV (p = 0.32, 0.96, and 0.76, respectively). CONCLUSIONS: Our experiments demonstrate that sequential bilateral isolated lung perfusion is safe in and well tolerated by the rat. This model can be used to investigate the safety and efficacy of staged perfusions with chemotherapeutic agents in the treatment of bilateral pulmonary metastases in the rat.

Glutathione metabolism in patients with non-small cell lung cancers.

Non-small cell lung cancer (NSCLC) is the leading cause of cancer death in the United States. Because NSCLC is highly chemoresistant, it is, usually not treatable. Altered glutathione (GSH) metabolism is thought to be one major mechanism of chemoresistance, and GSH levels are reported to be elevated in NSCLC. The main objective of this study is to delineate the potential mechanisms involved in elevation of tissue GSH, including extraction from the circulation by NSCLC. Twenty consecutive patients with NSCLC were enrolled. At the time of lobectomy, pulmonary artery and vein were identified, and blood flow was measured by an electromagnetic probe. Subsequently, blood samples were drawn from pulmonary artery, the vein draining the tumor-bearing lobe, and a normal lobe. Immediately after lobectomy, tumor and lung specimens were snap frozen. NSCLC tumor specimens had higher levels of GSH compared with lung tissue (20.8 +/- 9.4 versus 11.6 +/- 3.0 nmol/mg protein, respectively; P < 0.05). The tumor demonstrated higher activity of the enzyme gamma-glutamyl transpeptidase, a membrane-bound enzyme involved in transmembrane uptake of GSH, than lung tissue (41.9 +/- 26.4 versus 22.4 +/- 12.3 units/mg protein, respectively; P < 0.05). Also, the tumor-bearing lobe showed elevated extraction of GSH and two of its component amino acids compared with lung tissue (GSH uptake: 0.60 +/- 0.67 versus 0.20 +/- 0.40 microM/min, respectively; P < 0.05). NSCLC tumors are able to extract circulating GSH and its constituent amino acids to synthesize intracellular GSH. Increased activity of gamma-glutamyl transpeptidase may be one mechanism underlying increased GSH uptake by NSCLC.

Isolated lung perfusion with melphalan for the treatment of metastatic pulmonary sarcoma.

OBJECTIVE: Isolated lung perfusion allows the delivery of high-dose chemotherapy to the perfused lung and is an efficacious modality in the treatment of pulmonary metastases in the rat. Melphalan activity in this model was investigated. METHODS: TOXICITY STUDY: Maximum tolerated dose of melphalan delivered by means of isolated lung perfusion was determined by survival after contralateral pneumonectomy. PHARMACOKINETICS STUDY: Nineteen rats were treated with melphalan administered either by isolated lung perfusion (2 mg) or intravenously (2 mg or 1 mg). Lung, pulmonary effluent, and serum melphalan were analyzed by high-pressure liquid chromatography. EFFICACY STUDY: On day 0, 41 rats received an intravenous injection of 5 x 10(6) methylcholanthrene induced sarcoma cells. On day 7, rats either received intravenous melphalan (2 mg [n = 10]; 1 mg [n = 8]) or underwent left isolated lung perfusion with 2 mg of melphalan (n = 12). Isolated lung perfusion with buffered hetastarch in sodium chloride (Hespan, n = 11) was used as control. On day 14, pulmonary nodules were counted. TOXICITY: Maximum tolerated dose of melphalan delivered buy means of isolated lung perfusion was 2 mg. PHARMACOKINETICS: Left lung melphalan level was significantly higher in the isolated lung perfusion group (62.2 +/- 34.3 microg/gm lung) than in the intravenous treatment groups (6.9 +/- 1.9 microg/gm lung and 3.3 +/- 0.9 microg/gm lung, respectively) (p = 0.0002). EFFICACY: Significantly fewer left lung nodules were found in animals receiving melphalan by means of isolated lung perfusion (7 +/- 10) than in the groups receiving intravenous melphalan (60 +/- 21) or buffered hetastarch by isolated lung perfusion (84 +/- 52) (p = 0.01 and p = 0.0001, respectively). CONCLUSION: Isolated lung perfusion with melphalan is safe and effective in the treatment of pulmonary sarcoma metastases in the rat.

No-react detoxification process: a superior anticalcification method for bioprostheses.

BACKGROUND: Glutaraldehyde pretreatment of bioprosthetic heart valves is the major pathogenic factor in their calcific degeneration. This comparative study investigates the merit of the No-React aldehyde detoxification process as an alternative modifier of xenograft tissues. METHODS: Glutaraldehyde- and No-React-pretreated porcine aortic valve cusps were implanted subcutaneously in 6-week-old rats (n = 20). At 3, 6, and 14 weeks, randomly selected animals were sacrificed and the explants underwent mineral and morphologic analyses. Glutaraldehyde- and No-React-treated bovine pericardium and porcine aortic valve cusp were incubated in fibroblast cell culture plates. Cell viability was observed under reversed microscope at 6, 24, 48, and 96 hours. Erythrosin B dye exclusion test was used to validate percent cell death. RESULTS: Pretreatment with No-React significantly inhibited calcification of aortic cusp subcutaneous implants throughout the 14-week period (mean tissue Ca2+ content = 1.3 +/- 0.7 micrograms/mg at 14 weeks.) Glutaraldehyde-treated cusps underwent protracted calcification (Ca2+ content = 190.6 +/- 89.5 micrograms/mg; p < 0.01). Morphologic findings correlated with mineral analyses. One-hundred percent of fibroblast cells survived in the presence of No-React-treated tissue, with a growth pattern indistinguishable from control cell culture (ie, in the presence of no tissue). The cells incubated with glutaraldehyde-treated tissue showed signs of nonviability by 6 hours, with 100% cell death by 48 hours. Dye exclusion tests validated these findings. CONCLUSIONS: The No-React detoxification process completely abolishes the cytotoxicity of the xenograft tissue and inhibits calcific degeneration.

Complete cartilaginous duplication of the rib cage found in a cadaver: a first reported case.

We discovered a unique case of complete cartilaginous duplication of the rib cage in a cadaver, never previously described in the literature. A retrospective review of the patient's medical records revealed an antecedent history of progressive tobacco-related emphysema leading to death from end stage respiratory failure. Prior imaging studies consisting of plain radiographs and computed tomograms of the chest had failed to show several underlying cartilaginous duplications of the rib cage. The clinical significance and the potential contribution of this entity to this patient's clinical course remains unanswered.

Calcification of bovine pericardium: glutaraldehyde versus No-React biomodification.

BACKGROUND: Calcific degeneration is the most frequent cause of clinical dysfunction of glutaraldehyde (GA)-pretreated bioprosthetic heart valves. The No-React (NR) process has been shown to be a promising anticalcification treatment. In this comparative study, our objective was to delineate the advantages of the NR treatment over GA. METHODS: Bovine pericardial strips pretreated with GA and NR were individually incubated in calcium phosphate solution for 21 days at 37 degrees C. The pretreated bovine pericardium then was implanted subcutaneously in rats and retrieved at 14, 21, and 35 days after-implantation. Mineral and morphologic analyses were performed on each specimen. RESULTS: The NR-treated pericardium revealed significantly reduced in vitro calcification compared with the GA-treated tissue (mean tissue calcium content 1.3 +/- 0.2 versus 5.9 +/- 0.7 micrograms/mg; p < 0.001). Mineral analysis showed progressive calcification of the GA-pretreated pericardium over the period of implantation (calcium content increasing from 49.6 +/- 9.6 micrograms/mg after 2 weeks to 134.3 +/- 9.1 micrograms/mg at 5 weeks after-implantation). The NR-treated implants had calcified significantly less (p < 0.05) at each corresponding interval. Moreover, morphologic examinations demonstrated a protracted inflammatory response in the form of giant cell and mononuclear cell infiltration associated with intrinsic collagen disruption in the GA-treated tissue; the NR-treated pericardium maintained morphologic integrity with a mild inflammatory response. CONCLUSIONS: The NR biochemical process appears not only to attenuate pericardial calcification, but also to abort the host's destructive inflammatory response to the xenograft.