McGregor, Christopher G.A.

Cytolytic immunosuppression with OKT3 antibody has been shown to be highly effective in reducing the frequency of early allograft rejection in cardiac transplantation. Failure of OKT3 immunosuppression in the absence of anti‐OKT3 antibodies is a rare event, having been reported in only 3 patients who manifested predominantly vascular (humoral) rejection during OKT3 therapy. We report the first case of hemodynamically serious cellular rejection, without a demonstrable vascular rejection component, in a cardiac allograft recipient during OKT3 treatment. This case underscores the need to remain vigilant for signs of rejection in cardiac recipients during OKT3 immunosuppression.

Background —The role of surgical closure of patent foramen ovale (PFO) for cerebral infarction (CI) or transient ischemic attack (TIA) resulting from paradoxical embolism is unclear, and its effect on recurrence is unknown. Our objective was to determine the outcome of surgical closure of PFO in patients with a prior ischemic neurological event, define the rate of CI or TIA recurrence after PFO closure, and identify risk factors for these recurrences. Methods and Results —We retrospectively analyzed 91 patients (58 men, 33 women) with ≥1 previous cerebrovascular ischemic events who underwent surgical PFO closure between April 1982 and March 1998. The presence of a PFO with a right-to-left shunt was confirmed with transesophageal echocardiography. Mean age was 44.2±12.2 years. The index event was a CI in 59 and a TIA in 32; a Valsalva-like episode preceded the event in 15 patients. Deep venous thrombosis was documented in 9 patients, and a hypercoagulable state was identified in 10. Surgical closure was performed with extracorporeal circulation by either direct suture (n=82) or patch closure (n=9). Limited incisions were used in 18.7% of patients. There was no operative mortality. Morbidity included transient atrial fibrillation (n=11), pericardial drainage for effusion (n=4), exploration for bleeding (n=3), and superficial wound infection (n=1). Follow-up totaled 176.3 patient-years, and mean follow-up was 2.0 years. No one had a CI, and 8 had a TIA during follow-up, with 1 caused by temporal arteritis. Transesophageal echocardiography demonstrated all closures to be intact in these patients. The overall freedom from TIA recurrence during follow-up was 92.5±3.2% at 1 year and 83.4±6.0% at 4 years. Having multiple neurological events before PFO closure was the only significant risk factor for TIA or CI recurrence after closure by univariate analysis ( P =0.05); the small number of post-PFO closure cerebral ischemic events precluded multivariate analysis. Conclusions —Surgical closure of PFO can be performed with minimal morbidity and mortality. PFO closure may decrease the risk of recurrent stroke or TIA and may avoid lifelong anticoagulation in the young adult if there is no other indication. Recurrent cerebrovascular ischemic events after surgery should prompt further evaluation to identify causes other than paradoxical embolism.

There are limited data regarding the surgical management of primary pulmonary artery sarcomas (PPAS) because of their rarity and complicated diagnostic history. The objective of this study was to analyze our institution’s long-term surgical management outcomes for PPAS in the absence of a care pathway. From May 1997 to June 2013, 8 patients (mean age 60.6 ± 11.8 years; range, 40-73 years; 5 women and 3 men) underwent surgical intervention for PPAS at our institution. The most common computed tomography finding was a luminal filling defect obstructing the pulmonary artery (PA), without evidence of extraluminal extension. Three patients underwent debulking/pulmonary endarterectomy alone and 5 patients underwent a more radical resection with PA patch angioplasty, PA resection and reconstruction, pulmonary valve replacement, and unilateral pneumonectomy. The mean postoperative survival in this series was 3.8 ± 3.6 years (range, 1-11.9 years), with 2 radical surgical resection patients alive at 4.9 and 11.9 years, respectively. For those patients with incomplete resection, 3-dimensional (3D) models were created to demonstrate the advantage of a preoperative guide for a more complete resection and what it would entail. Six patients had local recurrences with mean disease-free interval of 14 ± 10.9 months (range, 2 months-2.5 years), and 2 patients with re-resections had an overall postoperative survival of 2.8 and 11.9 years, respectively. In our small cohort of PPAS, patients treated with radical surgical resection had better survival. The small number of PPAS cases in this series makes proving this association unlikely but warrants consideration.

Abstract Background: Patients with AL and congestive heart failure have a median survival of less than one year. Methods: Between 1994 and 2005, 11 patients underwent sequential heart transplant followed by autologous peripheral blood stem cell transplant (SCT) for treatment of AL. Patients had heart dominant AL with minimal/no other organ impairment and no evidence of multiple myeloma. Results: Patients ranged in age from 35 to 63 years (median 54). All had biopsy proven amyloidosis and monoclonal protein detectable in serum (73%) or urine (100%). Free light chain assay was available prior to SCT in 6 and was abnormal in all. All patients presented with NYHA Class III or IV heart failure. All but two patients had no other organ involved at the time of heart transplant. One patient had his heart transplant at another facility and had renal involvement at the time of heart transplant. One patient had peripheral nerve involvement documented prior to heart transplant. Five patients had progression of amyloid to involve other organs by the time of SCT. These included: renal (6), peripheral nerve (2), macroglossia (3), gastrointestinal (2). The median time from diagnosis to heart transplant was 3 months (range 1 to 5). The median time from heart transplant to SCT was 8 months, (range 3 to 24). Conditioning chemotherapy consisted of melphalan 200 mg /m2 (6 patients) or melphalan 140 mg/m2 (5 patients). Two patients died of complications before day +100, (TRM of 18%). Hematologic remissions were seen in 8 and organ responses in 3. Five were unable to be evaluated for organ response due to the heart transplant. Three died from progressive amyloidosis at 66, 56.7, and 55 months following SCT. The median survival is 56.7 months from SCT. Six are alive with a median follow-up of 24 months, range 9 to 90 months. Among the 6 surviving patients, one patient relapsed and one patient has failed to improve, but 4 patients are in continued remission. One patient developed secondary myelodysplastic syndrome. Conclusions: Heart transplant followed by SCT is feasible and offers durable remissions for carefully selected patients with cardiac AL. Figure Figure

Abstract Analysis of non‐Gal antibody induced after pig‐to‐baboon cardiac xenotransplantation identified the glycan produced by porcine beta‐1,4‐N‐acetyl‐galactosaminyltransferase 2 (B4GALNT2) as an immunogenic xenotransplantation antigen. The porcine B4GALNT2 enzyme is homologous to the human enzyme, which synthesizes the human SDa blood group antigen. Most humans produce low levels of anti‐SDa IgM which polyagglutinates red blood cells from rare individuals with high levels of SDa expression. The SDa glycan is also present on GM2 gangliosides. Clinical GM2 vaccination studies for melanoma patients suggest that a human antibody response to SDa can be induced. Expression of porcine B4GALNT2 in human HEK293 cells results in increased binding of anti‐SDa antibody and increased binding of Dolichos biflorus agglutinin (DBA), a lectin commonly used to detect SDa. In pigs, B4GALNT2 is expressed by vascular endothelial cells and endothelial cells from a wide variety of pig backgrounds stain with DBA, suggesting that porcine vascular expression of B4GALNT2 is not polymorphic. Mutations in B4GALNT2 have been engineered in mice and pigs. In both species, the B4GALNT2‐KO animals are apparently normal and no longer show evidence of SDa antigen expression. Pig tissues with a mutation in B4GALNT2, added to a background of alpha‐1,3‐galactosyltransferase deficient (GGTA1‐KO) and cytidine monophosphate‐N‐acetylneuraminic acid hydroxylase deficient (CMAH‐KO), show reduced antibody binding, confirming the presence of B4GALNT2‐dependent antibodies in both humans and non‐human primates. Preclinical xenotransplantation using B4GALNT2‐deficient donors has recently been reported. Elimination of this source of immunogenic pig antigen should minimize acute injury by preformed anti‐pig antibody and eliminate an induced clinical immune response to this newly appreciated xenotransplantation antigen.

Experiments were designed to determine how changes in the ratio of specific vascular endothelium-derived factors might affect reactivity of bronchial smooth muscle. The epithelium was mechanically removed from rings of third-order canine bronchi, and the rings were suspended in organ chambers for measurement of isometric force. Rings of pulmonary artery were cut; in some the endothelium was mechanically removed. The arterial rings were everted and pairs, with and without endothelium, were incubated with control solution, NG-monomethyl-L-arginine (L-NMMA), indomethacin, or both L-NMMA and indomethacin for 90 min. They were then inserted into the lumen of the bronchial rings. Cumulative concentration-response curves to acetylcholine and 5-hydroxytryptamine were obtained. There was no significant difference in response between bronchi containing arteries with or without endothelium incubated with control solution. Contractions of bronchi containing arteries without endothelium, incubated in either L-NMMA or indomethacin, increased from control. However, in rings containing arteries with endothelium, incubation with either inhibitor decreased bronchial contractions. Incubation with both inhibitors eliminated the difference. These results suggest that the vascular endothelium produces factors that can both contract and relax bronchial smooth muscle. With inhibition of production of either nitric oxide with L-NMMA or prostanoids with indomethacin, release of other endothelium-derived factors occurs that attenuates contractions of bronchial smooth muscle. Therefore, an imbalance in the ratio of production of endothelium-derived factors may contribute to bronchospastic disorders.

Circulating leukocytes activated during rejection of organ allografts could potentially have generalized effects on systemic blood vessels of the transplant recipient. Experiments were designed, therefore, to determine the function of the endothelium and smooth muscle of arteries from nontransplanted organs in dogs who received single lung transplants. Dogs underwent single lung allotransplantation and were immunosuppressed for 5 days. Immunosuppression was then withheld for 3 days, allowing rejection to occur. Dogs were studied at this time (rejecting) or following treatment for rejection for an additional 6-8 days (treated). Arteries from unoperated, untreated dogs also were studied to provide baseline responses of healthy tissue. Rings cut from left circumflex coronary, nonoperated native pulmonary, and renal arteries were suspended in organ chambers for measurement of isometric force. Endothelium-dependent relaxations to the calcium ionophore A23187 were not affected by rejection in any of the arteries. Contractions to angiotensin I were reduced significantly only in native pulmonary arteries. Contractions to KCI and endothelin-1 increased in renal arteries with endothelium during rejection. These contractions in renal arteries were reduced following treatment of rejection. None of the responses of the coronary arteries were affected significantly by rejection of the lung allograft. These results demonstrate that contractions of arteries in the transplant recipient's native organs are altered during rejection of lung allografts. The effects are organ specific, may include production of endothelium-derived contractile factors in renal arteries, and can be partially reversed by treatment of rejection.

Experiments were designed to evaluate endothelium-dependent responses of pulmonary arteries following prolonged exposure to oxygen-derived free radicals. Rings of canine pulmonary arteries with and without endothelium were suspended for measurement of isometric force in organ chambers and incubated with xanthine (10(-4)M) plus xanthine oxidase (0.015 U/ml) for 1 h in the absence and presence of either superoxide dismutase (SOD, 150 U/ml), catalase (1,200 U/ml), deferoxamine (10(-3)M), or a combination of all three scavengers. Xanthine plus xanthine oxidase caused significantly greater contractions of rings without compared with those with endothelium. In rings with endothelium, contractions were reduced by SOD or catalase but not by deferoxamine. Following 1 h of exposure to xanthine plus xanthine oxidase, endothelium-dependent relaxations to ADP were reduced but not those to bradykinin or the calcium ionophore A-23187 (calcimycin). Relaxations to ADP were not corrected by incubation with the antioxidants used singly or in combination during the exposure to xanthine plus xanthine oxidase. These results suggest that oxygen-derived free radicals generated from exogenously applied xanthine plus xanthine oxidase cause contractions of canine pulmonary arteries. In addition, even when contractions of rings with endothelium were prevented by SOD and catalase, subsequent expression of some but not all endothelium-dependent relaxations were reduced. Therefore, scavenging of oxygen-derived free radicals may prevent some but not all of the vascular injury caused by oxygen-derived free radicals.

An inducible isoform of nitric oxide synthase (type II, iNOS) is expressed in cardiac and vascular smooth muscle in response to inflammatory cytokines. The dog is an important large animal used for cardiovascular research including effects of exercise, heart failure, and allograft rejection. However, molecular probes for iNOS developed in other mammals have not been reliable for the study of iNOS induction in canine vascular smooth muscle. Experiments were designed to develop a molecular probe for canine iNOS. Smooth muscle cells were isolated from canine aortas. The cells ( passages 3–10) were incubated for 1, 3, 6, 12, 24, 48, or 72 h in the absence and presence of Escherichia coli lipopolysaccharide (LPS) to induce iNOS. Total RNA was isolated from the cells using standard techniques. RT-PCR with primers against conserved regions of all known iNOS enzyme was used to clone the iNOS cDNA. RT-PCR showed a single band only from cells treated with LPS. Cloned cDNA from cultured canine aortic smooth muscle cells has 84% homology to human, 81% to rat, and 81% to mouse iNOS gene. Identification of the cDNA for canine iNOS will be useful in the study of differential, transcriptional regulation of inducible (type II) compared with constitutive endothelial (type III) NOS in canine studies of allograft rejection and cardiovascular disease.