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The effects of pre-transplant blood transfusion vary from induction of antibodies and accelerated graft rejection, to prolonged survival and even tolerance. The beneficial 'transfusion effect' in allotransplantation is believed to be merely T-cell mediated. In xenotransplantation, T-cell independent mechanisms form a major hurdle. In this study we investigated the effects of pre-transplant hamster blood transfusion on the survival of hamster cardiac xenografts in T-cell deficient athymic nude rats. Nude rats rejected xenografts after 3.8 +/- 0.5 d (n = 8), and immunocompetent Lewis rats after 4.0 +/- 0.5 d (n = 8), following a similar IgM response (P = NS). Hamster blood transfusion 3 d before transplantation in nude rats led to an IgM response and long-term xenograft survival in 17/20. Timing was of importance: blood transfusion 7 d before transplantation resulted in 45% long-term xenograft survival (n = 20). Injection of purified hamster erythrocytes, leukocytes or minced heart also led to survival of xenografts for100 d in nude rats, but not in all cases. Second xenografts transplanted to long-term survivors did not provoke an IigM response, and were accepted for100 d (n = 4). Transfer of serum from long-term survivors to untreated nude rats resulted in survival of xenografts for100 d (n = 4). In Lewis rats pre-transplant blood transfusion induced hyperacute rejection of xenografts after 158 +/- 128 min (n = 8, P0.01). We conclude that pre-transplant hamster blood transfusion can induce long-term survival of hamster cardiac xenografts in T-cell deficient athymic nude rats. This blood transfusion effect is mediated by humoral factors and can be transferred by serum. Elucidation of underlying mechanisms might provide some insight into xenotransplantation nonresponsiveness of T-cell independent immunefactors.

Antibodies play a crucial role in the rejection of xenografts. We tested the hypothesis that xenografts are protected against antibody-mediated attack early after transplantation in a concordant model. We investigated the role of xenoreactive antibodies as a stimulus for protection and the effects of a total blockade of the antibody response by the leflunomide analog malononitrilamide 279. Hamster cardiac xenografts were transplanted to Lewis rat recipients. Second transplants and retransplants of xenografts were performed to untreated rats that had a xenograft in place for 3 d. Untreated rats rejected hamster cardiac xenografts after 4.0 +/- 0.0 d. Significant levels of anti-donor IgM, as measured by flowcytometry, were present on day 3 after transplantation (11.2% +/- 2.8 vs. 1.2% +/- 0.0 on day 0, P0.001). 'Fresh' second xenografts transplanted to rats that had a first xenograft in place for 3 d and had anti-hamster antibodies, underwent hyperacute rejection. The first xenografts remained functioning. Xenografts that were removed on day 3 from untreated rats and then retransplanted remained functioning. Xenografts that were removed on d 3 from rats that had been treated with malononitrilamide 279, 15 mg/kg/d and were retransplanted underwent hyperacute rejection. IgM levels at the time of removal were 1.1% +/- 0.5 in these rats and not different from baseline (P = 0.96). We conclude that xenografts are protected against antibody-mediated damage early after transplantation. The presence of anti-donor antibodies might be an essential stimulus for the induction of protection. There seems to be a delicate balance between the injurious and protective effects of antibodies. Treatment strategies that are designed to block antibody formation completely might prevent the induction of protection.

Nitric oxide (NO) limits the development of graft coronary artery disease (GCAD) in transplanted hearts. We hypothesized that l-arginine polymers administered to cardiac allografts ex vivo would translocate across vascular cellular membranes, up-regulate inducible nitric oxide synthase (iNOS) production of NO, and inhibit the development of GCAD.Three groups of PVG rat donor hearts were incubated with either 0.8 ml phosphate-buffered saline, (PBS, n=12) or 50 microM L-arginine polymer solutions of length five (R5, n=12) or nine (R9, n=12) prior to heterotopic transplantation into ACI recipients. Graft vessels were scored at POD 60 and 90 for percentage luminal narrowing (%LN), intima to media ratio (I/M), and percentage affected vessels (%AV). Translocation efficiency was determined by treatment with biotinylated polymers. NO production of treated aortic segments was determined in vitro by Griess reaction.Translocation efficiencies were 89+/-19% (R9), 7+/-10% (R5), and 0+/-0% PBS (ANOVA, P0.001) which corresponded to NO production in treated aortic segments of 0.175+/-0.17 (R9), 0.120+/-0.006 (R5), and 0.135+/-0.035 microM/mg (PBS), (ANOVA, P=0.002). GCAD scores at POD 60 were: %LN: 3.2+/-3.8% (R9), 12.6+/-6.7% (R5), 11.3+/-4.2% (PBS) (ANOVA, P=0.025); I/M: 0.03+/-0.04 (R9), 0.13+/-0.07 (R5), 0.12+/-0.05 (PBS) (ANOVA, P=0.037); %AV: 7+/-7% (R9), 19+/-7%(R5), 22+/-9%(PBS) (ANOVA, P=0.021). Reduction of GCAD parameters was maintained at POD 90.R9 efficiently translocated across cytoplasmic membranes, enhanced vascular NO production, and decreased neointimal hyperplasia. This ex vivo treatment may have a therapeutic role in preventing GCAD.

Heart and lung allograft dysfunction continues to be a problem in thoracic transplantation. Although medical therapy is often sufficient to restore allograft function, occasionally more invasive means are required. Mechanical assist devices, inhaled nitric oxide (iNO), and extracorporeal membrane oxygenation (ECMO) have been used with a modest degree of success in cases of refractory heart, lung, and heart-lung allograft failure. Allograft failure secondary to pulmonary hypertension often responds to iNO concentrations between 5 and 70 ppm without major toxicity. More severe cases may require mechanical assist devices or ECMO and carry higher risks of complications such as bleeding, neurological injury, and death. Utilization of and weaning from these interventions require intensive monitoring. Randomized, prospective studies are not ethically feasible, but case reports and patient series indicate the usefulness of mechanical circulatory support, iNO, and ECMO. This review focuses on the indications, complications, and patient survival rates associated with these modalities.

Nuclear factor-kappaB (NF-kappaB) is a transcription factor that upregulates adhesion molecules ICAM-1, VCAM-1, and ELAM-1. We hypothesized the use of ex vivo pressure-mediated delivery of transcription factor decoys (TFD) to NF-kappaB binding sites would decrease expression of adhesion molecules, and decrease reperfusion injury, acute rejection, and graft coronary artery disease (GCAD) in rat cardiac allografts.Heterotopic heart transplants were performed on donor hearts treated with saline, 10 mg/kg LPS, 160 micromol/L NF-kappaB TFD, or 160 micromol/L scrambled sequence (NF-SC) TFD for 45 min at 78 psi (6 atm). Transfection efficiency was determined with FITC-labeled TFD. Reverse transcription-PCR and immunohistochemistry was used to analyze adhesion molecule mRNA and protein expression, respectively. Apoptosis was measured with DNA fragmentation analysis. Reperfusion injury was assessed with cardiac edema, neutrophil infiltration, and histology. Acute rejection was determined by daily palpation. Allografts were assessed at POD 90 for the development of GCAD by computer-assisted image analysis to determine intimal:medial ratio and myointimal proliferation.Hyperbaric pressure was an effective method of NF-kappaB TFD delivery (P0.001 vs. controls). NF-kappaB TFD treatment led to decreased mRNA and protein expression of adhesion molecules. Treatment with NF-kappaB TFD led to a significant decrease in all reperfusion injury parameters compared to saline and NF-SC controls (P0.01 vs. controls). Higher levels of apoptosis were seen in allografts treated with NF-kappaB TFD compared to control allografts. NF-kappaB TFD treatment prolonged allograft survival over saline and NF-SC controls (P0.05). Myointimal proliferation and intimal:medial ratios in NF-kappaB TFD-treated allografts were significantly decreased compared to saline and NF-SC treatment (P0.00001).Ex vivo pressure-mediated delivery of NF-kappaB TFD is an effective method to block adhesion molcule expression and reperfusion injury in the immediate posttransplant period. Further, NF-kappaB TFD treatment prolongs allograft survival and decreases GCAD.

Graft vascular disease (GVD) is an incompletely understood process and the primary cause of late allograft failure. A nonhuman primate model was established to study the progression of GVD by using serial intravascular ultrasound (IVUS).Aortic allografts were transplanted below the inferior mesenteric arteries (IMA) into 6 rhesus monkeys. Removed and re-implanted aortic segments between renal arteries, and the inferior mesenteric arteries served as autografts. IVUS was performed at days 0, 24, 52, 80, and 98 after transplantation. Vessel area (VA) and lumen area (LA) were measured from each cross-section at 0.5 mm intervals. Intimal index (II=100x (VA-LA/VA)) and corresponding vessel volumes were calculated for the whole grafts. Histologic features were assessed from autopsy samples using computerized morphometric method and a score from 0 to 3 for GVD (0=none, 3=severe).In allografts, vessel volume and luminal volume decreased significantly (P0.05 for both) and the intimal index increased from 12% to 59% by day 98. These parameters remained unchanged in autografts. Histologic analysis of allografts showed concentric intimal hyperplasia and scattered mononuclear cell accumulations, whereas the autografts had only occasional eccentric intimal changes. The GVD-scores were significantly higher in allografts than in autografts (median 3 vs. 1, P=0.042).We introduce a nonhuman primate model of GVD that enables serial IVUS assessments of multiple parameters of GVD. Concentric intimal proliferation and decrease of vessel dimensions was observed in allografts as a consequence of alloimmunity. This is a potential new model for studying new therapies to prevent GVD or halt its progression.

Leukocyte function-associated antigen-1 (LFA-1, CD11a) monoclonal antibody (mAb) affects many leukocyte functions without cell depletion. We hypothesized that the use of a humanized, anti-rhesus modified LFA-1 mAb (H2C12) in rhesus monkeys would cause: (1) prolonged heart allograft survival, (2) inhibition of primary but not secondary antibody responses, and (3) minimal drug toxicity.Control (n=5) and H2C12-treated (n=7) (8-20 mg/kg i.v. on day -1 followed by 10 mg/kg/day) adult male rhesus recipients were inoculated with GP120 protein antigen on day -28 and -1 and grafted with heterotopic abdominal hearts (day 0). Donor-recipient pairs were equally MLR mismatched (4329.8+/-1124.1 CPM controls vs. 7289.0+/-1926.5 treated, P=NS). Mean heart allograft survival as evaluated by daily abdominal palpation was significantly prolonged in high dose recipients (23.0+/-2.6, n=4) vesus controls (8.2+/-1.3, n=5, P0.02, Mann-Whitney U test). H2C12 treatment did not produce signs of cytokine release or toxicity, was nondepleting, but down-modulated PBL CD11a expression to 43.4+/-3.6% (n=4) of control levels (n=5) at day 7 as demonstrated by flow cytometry. It had no effect on postoperative Con A or MLR and did not prevent mAb clearance due to the rhesus-antihuman antibody response. The addition of mycophenolate mofitil prevented rhesus-antihuman antibody response with therapeutic H2C12 levels seen for35 days.The use of this mAb to block CD11a had the benefit of being a well tolerated, highly targeted therapy. These are the first results showing that monotherapy with anti-leukocyte function-associated antigen-1 mAb prolonged survival of MLR mismatched allogenic cardiac grafts in primates.

Our purpose was to optimize hyperbaric pressure as a vector for ex vivo transfection of antisense oligodeoxynucleotides (AS-ODN) to intercellular adhesion molecule-1 to limit reperfusion injury (RI) in cardiac allografts. We investigated the effects of increased pressure, incubation time, and AS-ODN concentrations on transfection efficiency and toxicity.PVG (RT1c) donor hearts were heterotopically transplanted to ACI (RT1a) recipients. Donor hearts were harvested and the various groups were treated at: (1) different pressure (1-9 atm) for 45 min with 80 micromol/liter AS-ODN; (2) different incubation times (15 min to 6 hr) at 5 atm with 80 micromol/liter AS-ODN; 3) different AS-ODN concentrations (80-240 micromol/liter) at 5 atm for 45 min. Hearts were procured 24 or 72 hr after transplantation. Transfection efficiency was determined with fluorescein-labeled AS-ODN. The degree of RI was determined with biochemical and histological analysis. Increasing pressure from ambient (1 atm) pressure to pressures as high as 9 atm leads to a increase in transfection efficiency from 1.7+/-.5 to 62+/-3.9% and a reduction in RI. Increased incubation time up to 45 min increased transfection efficiency and reduced RI, but longer incubation times induced significant toxicity to the allograft. Increased AS-ODN concentrations improved transfection and reduced RI.Hyperbaric pressure is a safe and effective vector for the ex vivo delivery of AS-ICAM-1-ODN to rodent cardiac allografts and results in a reduction in reperfusion injury.

We studied the efficacy and tolerability of combined immunosuppressive therapy with cyclosporine A microemulsion (Neoral) plus the macrolide SDZ RAD 40-0 (2-hydroxyethyl) rapamycin (RAD) in a stringent cynomolgus monkey lung graft model in comparison with cyclosporine or SDZ RAD monotherapy.Thirty-nine cynomolgus monkeys received mixed lymphocyte reaction (MLR) mismatched unilateral lung transplants. Immunosuppressants were administered orally as single daily doses. The observation period was 28 days and follow-up included serial trough blood drug concentrations measured by high performance liquid chromatography/mass spectrometry, blood analyses, chest radiographs, open lung biopsies, as well as tissue drug concentrations and graft histology at necropsy.Graft biopsies in monkeys treated with vehicle (n=4), Neoral (day 1-7: 150 mg/kg/day; day 8-28: 100 mg/kg/day; n=6; mean +/- SE trough level (MTL): 292+/-17 ng/ml) or SDZ RAD monotherapy (1.5 mg/kg/day; n=6; MTL: 15+/-1 ng/ml) showed severe rejection. Coadministration in two transplant monkeys of Neoral (150/100 mg/kg/day) and SDZ RAD (1.5 mg/kg/day) caused their early death. In both animals, SDZ RAD blood levels were more than 5-fold higher than under monotherapy (MTL: 82+/-18 ng/ml). Simultaneous administration (n=6) of Neoral (150/100 mg/kg/day; MTL: 217+/-16 ng/ml) and SDZ RAD (0.3 mg/kg/day; MTL: 24+/-2 ng/ml) improved graft outcome (mild rejection). Side effects included renal failure (n=2) and seizures (n=1). Three monkeys survived to day 28. In this group the MTL for cyclosporin was 143+/-13 and for RAD 38+/-3. Staggered treatment completely prevented rejection in four of six grafts. However, five of six monkeys had moderate to severe diarrhea. In a concentration-controlled trial of simultaneously administered Neoral and SDZ RAD in transplant monkeys (target SDZ RAD MTL: 20-40 ng/ml; cyclosporine MTL: 100-200 ng/ml) all six monkeys survived with improved drug tolerability and an average biopsy score of mild rejection.Combination of orally administered SDZ RAD and Neoral showed excellent immunosuppressive efficacy in a stringent lung transplant model. The drug interaction and the narrow therapeutic index of this drug combination required careful dose adjustments to optimize tolerability and efficacy.

We hypothesized that ex vivo donor allograft transfection with antisense oligodeoxynucleotide (AS ODN) would inhibit the expression of intercellular adhesion molecule (ICAM)-1, an important mediator of T-cell adhesion and costimulation, and therefore suppress acute cardiac rejection.Hearts were transfected ex vivo with AS, reverse AS ODN, or saline by applying 3 atm pressure for 45 min at 4 degrees C. Grafts were then transplanted into allogenic recipients +/- treatment with leukocyte function-associated antigen (LFA)-1 monoclonal antibody (mAb) (1.5 mg/kg intravenously), cyclosporine (2.5 mg/ kg/day p.o.), or rapamycin (0.025 mg/kg/day intraperitoneally). Reperfusion injury was assessed in grafts harvested at early time points using the myeloperoxidase, %wet weight, and %contraction band necrosis assays; transfection efficiency was assessed using fluorescent microscopy; and efficacy of ICAM-1 blockade was assessed using immunohistochemistry. Other grafts were followed until rejection with donor/third-party skin grafting, adoptive transfer, and interleukin 2 infusion studies in selected recipients.Transfection was highly efficient (fluorescein isothiocyanate-ODN in 48+/-5% of total myocardial nuclei), nontoxic, and reduced the ICAM-1-positive area to 53+/-14% versus having no effect on MHC class I expression (n=4). The incidence of survival60 days after AS ODN + LFA-1 monoclonal antibody was 75%, significantly higher than other regimens.AS ODN hyperbaric transfection proved highly efficient, effective at ICAM-1 blockade, and induced cardiac allograft tolerance when combined with LFA-1 monoclonal antibody. This highly targeted alteration of allograft immunogenicity may have an important role in future immunosuppressive strategies.

Cystic fibrosis (CF) is associated with varying degrees of pleural inflammatory reaction that occurs as a result of chronic pulmonary infections and intervention to pleural space. The amount of pleural reaction is associated with the difficulty involved when performing the pneumonectomy at the time of lung replacement. The aim of this study is to identify possible pre-transplantation parameters that may predict the extent of pleural adhesion density. The charts of the 32 CF patients who underwent lung transplantation were reviewed. The degree of pleural adhesions was graded as none, minimal, moderate or severe, by extensive retrospective chart review of the operative and pathology reports. Available Brasfield radiographic scores, chest computerized tomographic (CT) scan scores, and pulmonary function test results were correlated to the pleural density grades. CT scans were scored by one radiologist as none, mild focal, moderate focal, diffuse mild or severe pleural disease. The presence of severe adhesions was associated with lower diffusion capacity corrected for volume (DL(CO)/VA) (p=0.0022) and older age (p0.05) at the time of transplant. The typical radiographic and pulmonary function findings of airway obstruction, parenchymal nodularity and air trapping did not correlate with pleural adhesion density. The eleven patients with severe pleural adhesions had a longer ICU course and remained intubated longer than the thirteen patients with none or minimal adhesions. The extent of severe adhesions associated with CF cannot be predicted by preoperative Brasfield radiographic scores of parenchymal disease or spirometry data. However, chest CT imaging and DL(CO)/VA measurements may be useful in predicting the extent of pleural adhesions and the degree of dissection difficulty associated with the pneumonectomies for lung transplantation in the CF recipients.

Chronic graft vascular disease in cardiac allografts results from coronary artery neointimal formation. Vascular ischemia has been shown to provoke the development of neointimal hyperplasia through endothelial damage. We used a rodent model of neointimal formation to test the in vivo effects of antisense oligodeoxynucleotides (AS ODN) specifically designed to block this process.Aortas from ACI rats were mock transfected or transfected with 18 base pair AS ODNs against the 5' start codon region of both CDC2 kinase, and proliferating cell nuclear antigen (PCNA) mRNA. Transfection was accomplished by placing the aorta in ODN solution (transfected group, 40 micromol/L of each sequence) or saline solution alone (mock-transfected group) and exposing to hydrostatic pressure (2 atm) for 24 hours at 4 degrees C. Vessels were then interposition-grafted into the abdominal aorta of untreated isogenic recipients and procured on postoperative days (POD) 1, 6, and 14.Nuclear localization of fluorescein isothiocyanate ODN was observed in 81%+/-3% of medial smooth muscle cells at 24 hours after interposition grafting and reperfusion. Efficacy of AS ODNs at blocking CDC2 kinase and PCNA was verified on POD 6 by enzyme-linked immunosorbent assay. This blockade significantly reduced ischemically induced vascular narrowing on POD 14 as assessed by use of computerized image analysis (3.85%+/-2.45% luminal narrowing for transfected vs 7.11%+/-2.03% for control subjects, p0.03).Our data show the efficacy of AS ODN at blocking rat PCNA and CDC2 kinase up-regulation provoked by ischemia. This ex vivo approach had beneficial effects against vascular narrowing in a rodent model of ischemically induced neointimal hyperplasia, an antigen-independent factor important in the development of subsequent chronic graft vascular disease.

The objective of this study was to determine if air trapping, as detected on expiratory high-resolution CT (HRCT), is useful as an indicator of bronchiolitis obliterans (BO) in lung transplant recipients.Corresponding inspiratory and expiratory HRCT images at five different levels and spirometry were obtained in 21 lung transplant recipients. Eleven patients had BO proved by transbronchial biopsy specimens; the remaining 10 patients had no pathologic or functional evidence of airways disease. Two "blinded" observers assessed the inspiratory images for the presence of bronchiectasis and mosaic pattern of lung attenuation, and the expiratory images for presence and extent of air trapping. Statistical comparison of the frequency of HRCT findings between patients with and without BO was performed using Fisher's Exact Test.On inspiratory images, bronchiectasis and mosaic pattern of lung attenuation were present in 4 (36%) and 7 (64%) of 11 patients with BO, and 2 (20%) and 1 (10%) of 10 patients without BO (p0.05 and p0.05), respectively. The sensitivity, specificity, and accuracy of bronchiectasis and mosaic pattern for BO were 36%, 80%, and 57%, and 64%, 90%, and 70%, respectively. On expiratory images, air trapping was found in 10 of 11 (91%) patients with BO compared to 2 of 10 (20%) patients without BO (p0.002). Air trapping was found to have a sensitivity of 91%, specificity of 80%, and accuracy of 86% for BO. Air trapping was identified in one patient with BO who had normal results of baseline spirometric function tests.Air trapping, as detected on expiratory HRCT, was the most sensitive and accurate radiologic indicator of BO in the lung transplant population.

To ascertain if operative technique has any bearing on outcome, the surgical results after aortic root replacement using either a composite valve graft (CVG) or a separate graft and valve (GV) were analyzed.Three hundred and ninety consecutive, nonrandomized patients treated for aortic valve disease and ascending aortic aneurysm (n=278) or type A dissection (n=112 [45 acute]) between 1965 and 1995 were analyzed retrospectively. One hundred and thirty-five patients received a CVG, and 255 had separate GV replacement. Mean age was 52+/-16 years (+/-1 SD). Eighty-two patients (44% of the CVG group) had the Marfan syndrome (MFS). Follow-up (96% complete) totaled 2247 patient-years and extended to 27 years. The operative mortality rate was 10+/-3% (+/-70% confidence limits) for patients receiving a CVG and 15+/-2% for GV replacement (P=NS). The 15-year actuarial survival estimate was higher for the CVG group (53+/-14% [+/-SEM] versus 36+/-4%, P=.037). Seven patients in the CVG group required reoperation on the aortic valve or ascending aorta, as did 49 in the GV group. The probabilities of freedom from reoperation on the aortic rootwere 82+/-9% and 75+/-4% at 10 years for the CVG and GV group (P=NS). Thirty variables were analyzed in a multivariate model: pulmonary disease, higher New York Heart Association functional class, and longer cardiopulmonary bypass time were linked with higher operative mortality risk; older age, emergency operation, coronary artery disease, and liver dysfunction were independent determinants of late death. Younger age and use of a bioprosthesis were predictors of late reoperation. Type of procedure (GV versus CVG) was not a significant predictor of any outcome variable.The long-term results after CVG or GV were similar, which reflects proper patient selection. Use of a composite valve graft theoretically confers more protection against recurrent aortic root aneurysm, and, unless one opts for a valve-sparing aortic root replacement procedure, is most appropriate for younger patients, those with the MFS (including acute dissections), and others with marked pathological involvement of the sinuses. On the other hand, use of a separate GV should not be abandoned; in carefully selected patients (and if properly performed, eg, excision of the sinuses), GV also provides satisfactory results.

In utero tolerance induction has potential application in pediatric heart transplantation. Immunotolerance appears to be more easily induced in the fetus before full immunocompetence is established; however, the mechanisms behind this phenomenon are still undefined.One hundred thirty Lewis (RT1l) rat fetuses from 10 litters were inoculated intraperitoneally at 18 days gestation with 1 x 10(7) ACI (RT1a) rat fetal liver cells. Fifty of the 100 viable neonates successfully brought to term were grafted with neonatal ACI skin within 24 hours of birth and heterotopic ACI hearts at 8 to 10 weeks of age (group 1A); the remaining 50 neonates only received heterotopic ACI heart grafts at 8 to 10 weeks (group 1B). Control groups consisted of 50 Lewis fetuses (five litters) inoculated in utero with phosphate-buffered saline solution (group 2) and 50 Lewis fetuses (five litters) that received no inoculum (group 3); all of these surviving progeny received both neonatal ACI skin and adult ACI cardiac allografts. Skin and cardiac grafts were monitored by daily visual inspection and palpation, respectively. Limiting dilution analysis was performed among all groups to assess precursor cytotoxic lymphocyte frequencies. Likewise, peripheral blood lymphocyte and splenocyte populations were analyzed with flow cytometry to detect allogeneic chimerism.Abortion rates among groups 1, 2, and 3 were 23% (30/130 abortions), 10% (5/50 abortions), and 6% (3/50 abortions), respectively. Tolerance to both ACI skin and cardiac allografts was induced in 14 of the 50 group 1A Lewis recipients (28%). Tolerance was not achieved in any of the recipients in groups 1B, 2, or 3. Limiting dilution analysis among all groups revealed a marked reduction of precursor cytotoxic T-lymphocytes in tolerant allograft recipients compared with recipients in the other groups. Flow cytometry detected significant splenocyte chimerism among tolerant rats; significant peripheral blood chimerism was not noted.We describe allogeneic tolerance induction in utero to both rat skin and heart tissue by use of donor-strain fetal liver cells. Compared with previous studies with adult splenocytes as the tolerogen, we achieved a higher frequency of tolerance with a markedly lower cell inoculum and lower abortion rate. Allogeneic chimerism was noted in the tolerant recipients, suggesting hematopoietic stem cell engraftment. Cytotoxic T-lymphocyte precursor frequencies were markedly depressed in tolerant animals. Interestingly, both donor-strain fetal liver cells and neonatal skin grafts were required to induce tolerance. These data suggest a period of hematopoietic "education" during and shortly after hematopoietic stem cell engraftment.

Acute rejection has emerged as an important risk factor for obliterative bronchiolitis after lung transplantation. We performed a multivariate analysis to assess the impact of additional variables.Seventy-four recipients (48 heart-lung, 18 single-lung, and 8 bilateral-lung recipients) who survived longer than 90 days and underwent transplantation more than 15 months before data analysis were included in this study. Several variables were entered into a Cox regression analysis to determine their association with the development of bronchiolitis obliterans syndrome.Bronchiolitis obliterans syndrome developed in 48 (65%) of 74 patients. Significant correlations were detected for acute rejection score, defined as the sum of pathologic grades of each separate acute rejection episode (p = 0.0004, likelihood ratio test value = 12.4) and for lymphocytic bronchiolitis (p = 0.03). In a bivariate model, episodes of organizing pneumonia and bacterial or fungal pneumonia significantly increased the likelihood ratio test value of the acute rejection score. The addition of the cytomegalovirus infection score, reflecting the frequency and severity of infection, to the combination of the acute rejection score and episodes of bacterial or fungal pneumonia resulted in a further significant increase in the likelihood ratio test value. Significant risk factors for moderate to severe stages of airflow limitation were at least one episode of acute rejection of gradeor = 2, younger recipient age, and any acute rejection episode 180 days or longer after transplantation.Increasing frequency and severity of acute rejection episodes are strongly associated with the development of bronchiolitis obliterans syndrome. Lymphocytic bronchiolitis appeared to be significant by univariate analysis, but in a two-risk factor model, it did not augment the influence of acute rejection. Organizing pneumonia, bacterial or fungal pneumonia, and increasing severity and frequency of cytomegalovirus infections potentiate the effect of acute rejection. Late episodes of acute rejection and younger recipient age increase the risk for development of advanced disease.

Induction of immunological tolerance in utero has potential application in pediatric cardiac transplantation. We describe an inexpensive, reproducible, and well-characterized model of allogeneic tolerance induction in utero using donorstrain fetal liver cells.Each of 9 Lewis (LEW, RTl1) rat fetuses in one litter (group 1) and 10 LEW fetuses in another litter (group 2) were inoculated intraperitoneally at 17 to 18 days of gestation with 1 x 10(6) ACI (RTla) rat fetal liver cells. Ten LEW fetuses in a third litter inoculated with PBS (group 3) and 10 LEW noninoculated fetuses in a fourth litter (group 4) served as controls. The LEW rats were brought to term, and groups 1, 3, and 4 were grafted with neonatal ACI skin within 24 hours of birth and with heterotopic ACI hearts at 8 to 10 weeks of age; group 2 rats received only an ACI heart graft at 8 to 10 weeks. Skin and cardiac grafts were monitored by daily visual inspection and palpation, respectively. Peripheral blood lymphocyte (PBL) populations in all LEW recipients were analyzed with flow cytometry. All LEW fetuses survived to term and developed normally. The ACI skin and cardiac allografts on 3 of the 9 LEW rats in group 1 are viable to date (skin,170 days; cardiac,100 days). The remaining 6 recipients of this group and all animals in groups 2, 3, and 4 rejected their skin and cardiac grafts by postgrafting day 7. Significant PBL chimerism (1.57%) was observed in only 1 tolerant rat.We describe allogeneic tolerance induction in utero to both rat skin and cardiac tissue with donor-strain fetal liver cells. Compared with previous studies using adult splenocytes as the tolerogen, we achieved a higher frequency of tolerance with a markedly lower cell inoculum and no abortions. Interestingly, both donor-strain fetal liver cells and neonatal skin grafts were required to maintain tolerance into adulthood. Immunocompetence sufficient to reject allografts was noted in neonates, and PBL chimerism was not prominent in tolerant recipients.

Cytomegalovirus infection threatens pulmonary allograft survival and function. This retrospective study details the experience of ganciclovir prophylaxis against cytomegalovirus infection and its sequelae.Eight-nine lung and heart-lung transplant recipients with positive cytomegalovirus serology were analyzed. The 37 recipients who underwent transplantation before September 1989 received no prophylaxis. The 52 subsequent recipients received ganciclovir prophylaxis.Thirty-six non-prophylaxed versus 42 prophylaxed patients had cytomegalovirus events with cumulative incidences of 100% and 86% (p0.01), and median onsets of 37 +/- 21 versus 85 +/- 35 days, respectively (p0.01); 22 non-prophylaxed versus 27 prophylaxed patients had cytomegalovirus pneumonitis with cumulative incidences of 60% and 55% (p0.01), and median onsets of 34 +/- 14 and 84 +/- 26 days, respectively (p0.01). Respiratory failure caused by cytomegalovirus pneumonitis developed in nine of the non-prophylaxed versus two of the prophylaxed patients (p0.01). The significant estimated survival benefit in patients who received prophylaxis (p = 0.04) was not apparent when reanalysis was performed after exclusion of patients with respiratory failure (p = 0.36). Ganciclovir prophylaxis produced a significant delay in the development of obliterative bronchiolitis with a median time to onset of 1072 +/- 280 days versus 432 +/- 189 days for the non-prophylaxis cohort (p0.01).Ganciclovir prophylaxis (1) improves recipient survival by reducing the severity of disease and essentially eliminating respiratory failure caused by cytomegalovirus pneumonitis, (2) reduces the incidence and delays the onset of cytomegalovirus events and pneumonitis, and (3) delays the onset of obliterative bronchiolitis.

Adult heart-lung transplantation was initiated at Stanford in 1981 and the first pediatric heart-lung transplantation was done in 1986. Intermediate-term results of pediatric heart-lung transplantation at Stanford University are presented.A retrospective review of the records of all pediatric heart-lung transplantations done since 1986 was conducted.Nineteen heart-lung transplantations were done in 17 patients. Ages ranged from 2 months to 18 years with a median age of 10 years. At the time of transplantation 5 patients were infants, 7 children, and 7 adolescents. The mean follow-up was 29 +/- 6.2 months (range 1 to 77, median 16) and follow-up was 100% complete. Diagnoses were congenital heart disease in 13, primary pulmonary hypertension in 2, and cystic fibrosis, cystic lymphangiectasia, viral pneumonia, and obliterative bronchiolitis in 1 each. Median wait on the heart-lung transplantation list was 91 days (range 2 to 707). All patients had New York Heart Association class III to IV symptoms, two were receiving ventilator support, and six were receiving oxygen. Fifteen of 19 transplant recipients were discharged from the hospital. The 30-day operative mortality rate was 5.2% (1 of 19). The actuarial survival at 1, 3, and 5 years for all patients was 67%, 51%, and 41%, respectively, and for hospital survivors was 82%, 62%, and 51%. The cause of death was obliterative bronchiolitis in 4, multisystem organ failure in 3, and graft coronary artery disease and chronic airway disease in 1 each. Three patients required retransplantation, 2 because of obliterative bronchiolitis and 1 because of viral pneumonia. Two patients underwent repeat heart-lung transplantation and 1 patient underwent single lung transplantation. Rejection was diagnosed in 73% of recipients, and obliterative bronchiolitis has developed in 32% of recipients.Survival in pediatric heart-lung transplantation approximates that in the adult procedure at 1, 3, and 5 years. Long-term survival has been achieved but the primary factors limiting further improved survival remain infection and obliterative bronchiolitis.

Obliterative bronchiolitis is a progressive form of obstructive airway disease that threatens long-term survival in lung transplant recipients. Its incidence and the long-term survival of lung transplant recipients with obliterative bronchiolitis are unknown.The results of 89 heart-lung and 13 bilateral sequential lung transplant survivors beyond 90 days of their operation were analyzed. The date of diagnosis for obliterative bronchiolitis was established histologically (presence of submucosal fibrosis) or physiologically by a persistent reduction in the forced vital capacity to less than 0.7 for greater than 6 weeks. There were 43 patients without obliterative bronchiolitis and 59 patients with obliterative bronchiolitis.No differences were found in the mean age and gender ratios between the two groups. The actuarial 1-, 5-, and 10-year percentage freedom from obliterative bronchiolitis was 72 +/- 4.6, 30 +/- 5.6, and 15 +/- 7.4, respectively, with a median onset of 689 days (range 55 to 3404 days). About half the patients with biopsy-proven obliterative bronchiolitis had a fall in their forced expiratory flow at 50% of forced vital capacity/forced vital capacity nearly 4 months before fulfilling the forced expiratory volume in 1 second criteria established by the Working Group on chronic lung dysfunction. The actuarial 1-, 5-, and 10-year percentage survival of obliterative bronchiolitis negative patients was 90 +/- 4.5, 74 +/- 8.4, and 66 +/- 10.6, respectively, versus 90 +/- 3.9, 49 +/- 6.9, and 27 +/- 10.0, respectively, for obliterative bronchiolitis positive patients (p = 0.38). The actuarial 1-, 3-, 5-, 8-, and 10-year percentage survival of lung transplant recipients after the diagnosis of obliterative bronchiolitis was 74 +/- 5.8, 50 +/- 7.5, 43 +/- 7.8, 23 +/- 8.7, and 11 +/- 9.1, respectively, with a median survival of 1084 days (range 0 to 3442 days).The forced expiratory flow at 50% of forced vital capacity/forced vital capacity is a more sensitive indicator for the early detection of obliterative bronchiolitis than the forced expiratory volume in 1 second after heart-lung or bilateral sequential lung transplantation. The obliterative bronchiolitis negative group survival tends to be better than the obliterative bronchiolitis positive group. The obliterative bronchiolitis positive lung transplant recipients have reasonable outcomes with a median survival time of nearly 3 years after the diagnosis of obliterative bronchiolitis. Earlier detection of obliterative bronchiolitis and refinements in management may further improve these results.

Bronchoscopy with transbronchial biopsy (TBBx) and bronchoalveolar lavage (BAL) has an appreciable yield in detecting asymptomatic abnormalities in heart-lung transplant recipients (HLTR) during the early postoperative period. The utility of annual surveillance procedures has not been critically evaluated. We reviewed all annual bronchoscopies performed on 29 HLTR to determine the frequency of asymptomatic abnormalities. Surveillance bronchoscopies (SB) were performed on asymptomatic subjects with unchanged lung function compared with baseline. Surveillance/clinical bronchoscopies (SCB) were those performed in patients with stable decrements in lung function. Nineteen patients underwent 48 SB and 8 had 18 SCB. Five of 15 (33%) SB performed at one year yielded an abnormal TBBx (1 grade 2 acute rejection [AR], 1 grade 1 AR, 1 grade 1 AR with obliterative bronchiolitis [OB] and 2 Pneumocystis carinii pneumonia). At 2 or more years, TBBx was abnormal in 2 of 33 (6%, p = 0.024 compared with first year TBBx) (1 grade 1 AR, 1 lymphocytic bronchiolitis). Pathogens were identified in BAL in 19 (40%) SB. Fourteen (78%) SCB were abnormal. Nine (50%) revealed an abnormal TBBx (all OB), but only 2 (11%) of these altered patient management. Seven (39%) demonstrated pathogens in BAL. We conclude that in HLTR (1) surveillance TBBx rarely yields positive findings 2 or more years posttransplant, (2) surveillance TBBx seldom alters management in patients with stable decrements in lung function, and (3) BAL is useful to screen for potential pathogens.

Leflunomide, an isoxazole derivative, has been shown to effectively prolong rodent allograft and cardiac xenograft survival. In vitro studies suggest that leflunomide inhibits the production of donor-specific antibodies and is capable of blocking both T- and B-cell proliferation. In light of the significant role that humoral immunity is believed to play in chronic pulmonary allograft rejection as well as hyperacute and accelerated acute xenograft rejection, we examined the efficacy of leflunomide in prolonging pulmonary allografts and xenografts and its effect on donor-specific antibody production.Lungs from Brown Norway rats or Golden Syrian hamsters were orthotopically transplanted into Lewis rat recipients. Allograft recipients were treated daily for 14 days with vehicle, leflunomide (15 mg/kg/day orally), or cyclosporine (7.5 mg/kg/day orally) starting on the day of grafting (day 0). In xenograft recipients, leflunomide (20 mg/kg/day orally) or cyclosporine (7.5 mg/kg/day orally) treatment initiated on day 0 was continued until complete graft rejection; the leflunomide dosage was reduced to 10 mg/kg/day after day 14 because of weight loss and leukopenia. Graft viability was assessed with chest radiography in conjunction with open lung biopsies. Toxicity was monitored with body weight measurements, complete blood counts, and serum chemistries. Flow cytometric analysis of serum samples taken from graft recipients on day 7 was used to measure donor-specific immunoglobulin M and immunoglobulin G antibody titers.Allograft and xenograft control animals receiving vehicle yielded graft survival times of 6.0 +/- 0.0 and 5.4 +/- 0.6 days, respectively. Although xenograft recipients treated with cyclosporine (7.5 mg/kg/day orally) showed no significant graft prolongation, pulmonary allograft survival in recipients receiving cyclosporine alone was significantly prolonged to 28.2 +/- 0.7 days. Leflunomide-treated allograft (15 mg/kg/day orally) and xenograft (20 mg/kg/day orally) recipients displayed significant graft prolongation to 28.2 +/- 0.7 days and 15.8 +/- 3.3 days, respectively. Cyclosporine (7.5 mg/kg/day orally) enhanced the effect of leflunomide (20 mg/kg/day orally) in xenograft recipients with a mean graft survival time of 36.0 +/- 3.0 days achieved when both drugs were administered concomitantly. Cyclosporine significantly suppressed donor-specific immunoglobulin G antibody titers in both pulmonary allograft and xenograft recipients while not affecting immunoglobulin M levels. Leflunomide markedly suppressed both immunoglobulin G and immunoglobulin M donor-specific antibody titers in allograft and xenograft recipients. Except for mild leukopenia and anemia, both cyclosporine- and leflunomide-treated allograft recipients showed no evidence of toxic side effects after 14 days of therapy. However, leflunomide-treated xenograft recipients displayed significant weight loss, anemia, and leukopenia after 14 days of treatment with one death in each treatment group.

The current critical shortage of cardiac allograft donors means that the decision to offer a patient repeat heart transplantation must be carefully considered. Since 1968, a total of 66 heart retransplantation procedures (63 first-time and three second-time) have been performed in 63 patients at Stanford.There were 52 male and 11 female patients, ranging in age from 3 to 62 years with a mean age of 41 years. Indications for retransplantation were primary allograft failure in nine patients, acute rejection in 17, graft atherosclerosis in 37, and constrictive disease in three. Six of the seventeen patients (35%) who underwent retransplantation before 1981 died in the hospital, and none are currently alive. Of the 46 patients who underwent retransplantation since 1981 treated with cyclosporine-based immunosuppression, 11 (24%) died in the hospital. Actuarial survival estimates for the whole retransplantation group at 1, 5, and 10 years were 55% +/- 8%, 33% +/- 8%, and 22% +/- 7%, respectively.This survival was significantly worse (p0.05) than that in patients undergoing primary heart transplantation (81% +/- 2%, 62% +/- 2%, 44% +/- 13% at 1, 5, and 10 years). Those patients who underwent retransplantation for graft atherosclerosis since 1981 had a significantly better 1-year survival (p0.05) than those who underwent retransplantation for allograft rejection (69% +/- 10% versus 33% +/- 16%), but the 5-year survival was similar in both groups (34% +/- 11% versus 33% +/- 16%). Since 1981, actuarial freedoms from infection and rejection were 22% +/- 8% and 41% +/- 9%, respectively, at 1 year, and 7% +/- 7% and 36% +/- 9% at 5 years. Patients with cyclosporine-induced renal dysfunction (serum creatinine level of greater than 2.0 mg/dl) had a high probability of requiring postoperative dialysis and also of death after retransplantation. Three patients with significant cyclosporine-induced renal dysfunction underwent simultaneous kidney transplantation and heart retransplantation, and all were alive and well at the time this article was written. Sixteen patients were also currently alive at a mean follow-up of 44 months, and 15 were in New York Heart Association functional class I.We continue to list carefully selected candidates with good rehabilitation potential for heart retransplantation.

We assessed the long-term results of our experience with 109 patients with end-stage cardiopulmonary disease who underwent primary combined heart-lung transplantation at Stanford University Medical Center between March 1981 and January 1994. Average recipient age was 31 +/- 10 years (mean +/- standard deviation) median, 31 years; range, 1 month to 52 years. Recipient diagnoses included primary pulmonary hypertension (31%), Eisenmenger's syndrome (39%), complex congenital heart disease (8%), cystic fibrosis (14%), bronchiectasis (2%), and emphysema (3%). Immunosuppression was with cyclosporine and a tapering regimen of corticosteroids. In 1986 azathioprine was added, and since 1987 induction therapy with OKT3 has been employed. Actuarial survival rates at 1, 5, and 10 years were 68% +/- 4.6%, 43% +/- 5.4%, and 23% +/- 8.1%, respectively (mean +/- 1 standard error of the mean). Fourteen deaths occurred in the hospital for an operative mortality rate of 12.8% +/- 3.3%, and 61 deaths occurred overall. Causes of death included hemorrhage (five patients), infection (21), rejection (one), nonspecific pulmonary failure (four), graft coronary artery disease (six), and obliterative bronchiolitis (eight). Infection, rejection, and obliterative bronchiolitis were the major complications. Only 20% +/- 3.9% of patients were free from any infection 3 months after transplantation. Heart and lung rejection commonly occurred asynchronously; actuarial estimates of freedom from isolated lung rejection at 1 and 5 years were 47% +/- 5.2% and 40% +/- 5.6%, respectively. For simultaneous heart and lung rejection these estimates were 87% +/- 3.5% and 86% +/- 3.8%, and for isolated heart rejection 63% +/- 5.1% and 51% +/- 6.4%, respectively. Although graft coronary artery disease developed less frequently than in patients after isolated heart transplantation (90% +/- 4.6% of patients were free of graft coronary artery disease at 5 years), obliterative bronchiolitis remains a major long-term complication and cause of morbidity and mortality. Actuarial estimates of freedom from obliterative bronchiolitis at 1, 5, and 10 years were 71% +/- 5.1%, 51% +/- 6.1%, and 42% +/- 7.8%, respectively. These results show satisfactory early and medium-term outcome after combined heart-lung transplantation but also underscore that much progress is needed in controlling infection, rejection, and obliterative bronchiolitis, all of which remain as major impediments to long-term survival.

The use of hearts from large domestic animals represents a potential solution to the current human donor shortage. However, xenogeneic hyperacute graft rejection remains a major barrier to xenotransplantation. The purpose of this study was to use an ex vivo preparation to study variables that may correlate with hyperacute rejection in cardiac xenografts. Freshly excised hearts from 37 anesthetized pigs (10 to 37 kg) were perfused at 37 degrees C through the aorta with retrograde flow. The hearts functioned in a nonworking mode for 4 hours or until irreversible cardiac dysfunction occurred. Various perfusates were used: fresh whole autologous pig blood (n = 4), dog blood (n = 3), baboon blood (n = 5), human packed red blood cells (n = 2), human whole blood (n = 10), human whole blood and plasma (n = 3), and human plasma (n = 9), to which a modified Krebs-Henseleit bicarbonate buffer solution was added. Rapid loss of function was uniform and occurred most quickly (13 to 18 minutes) for hearts perfused with dog blood and human plasma. Isolated cardiac perfusion provided a means for the analysis of the cellular and plasma components of human blood to define which were required for rapid loss of function. The results indicated that the reaction was mediated by components present only in plasma.

Intramural hematoma of the thoracic aorta (IMH) is a diagnosis of exclusion and represents spontaneous, localized hemorrhage into the wall of the thoracic aorta in the absence of bona fide aortic dissection, intimal tear, or penetrating atherosclerotic ulcer. This process may arise from primary vasa vasorum hemorrhage within the aortic media or rupture of an atherosclerotic plaque. The clinical presentation of patients with IMH mimics that of acute aortic dissection; moreover, considerable diagnostic confusion exists despite the use of many different imaging modalities. The optimal mode of management of patients with IMH (medical versus medical plus surgical) remains problematic because of the paucity of information available.Thirteen patients with IMH were managed at two medical centers between 1983 and 1992. Patients with IMH caused by giant penetrating atherosclerotic ulcers were specifically excluded. There were 8 women and 5 men (mean age, 70 years [range, 54 to 82 years]). The admitting clinical diagnosis was acute aortic dissection, and all patients had a history of hypertension. There was no evidence of aortic dissection or intimal disruption as assessed by computed tomographic (CT) scan (n = 11), aortography (n = 10), magnetic resonance imaging (MRI) scan (n = 9), transesophageal echocardiography (TEE) (n = 6), or intravascular ultrasound (n = 1). The diagnosis of IMH was established by exclusion. The descending thoracic aorta was involved in 10 cases and the ascending/arch in 3. Conservative medical management was attempted initially. All 3 patients with IMH involving the ascending aorta ultimately required operative intervention, and 2 individuals died; 2 of 10 patients with descending aortic involvement eventually underwent surgery. Average hospital stay was 11 days; the mean follow-up interval for discharged patients was 29 months.IMH is a distinct pathological entity, should not be confused with aortic dissection, and probably will be identified more frequently in the future. All patients with IMH should be monitored carefully and treated with aggressive antihypertensive therapy. Frequent serial assessment is necessary using TEE or MRI/CT scans. Based on this small experience, patients with ascending/arch IMH, ongoing pain, or IMH expansion should probably undergo early graft replacement. Patients with IMH involving the descending thoracic aorta who have no evidence of progression and become pain free can probably be treated conservatively but require antihypertensive therapy and serial aortic imaging surveillance indefinitely.

Although the major limitation of porcine valves is their finite durability, no controlled clinical data exist regarding the relative durability of the two porcine bioprostheses implanted most commonly today, the Carpentier-Edwards (C-E) and Medtronic Hancock I (H) valves.To assess this question, 174 patients undergoing aortic (AVR) or mitral (MVR) valve replacement with a bioprosthesis between March 1980 and March 1982 were randomized to receive either a C-E or a H valve. There were 102 AVRs (54 C-E and 48 H) and 74 MVRs (39 C-E and 35 H). For both the AVR and MVR cohorts, the average patient age was 58 +/- 14 years (+/- SD). The male/female ratio was 2.2:1 for AVR and 0.57:1 for MVR. Clinical follow-up was undertaken periodically; the most recent follow-up closing interval was July through October 1992, and current follow-up was 96% complete. Cumulative follow-up totaled 1369 patient-years (mean, 7.7 +/- 3.6 years; median, 9.1 years; maximum, 12.0 years). The main focus of this analysis was bioprosthetic durability, using the AATS/STS guidelines defining "Structural Valve Deterioration" (SVD). Multivariate analysis revealed that (younger) age was the only significant (P = .024) independent predictor of SVD. Valve manufacturer (C-E versus H) and valve site (aortic versus mitral) did not emerge as significant independent risk factors for SVD. Actuarial rates (Cutler-Ederer) expressed as percent free of SVD (+/- SEM) at 10 years (n = number of patients remaining at risk) were 71 +/- 7% and 59 +/- 9% for the C-E (n = 26) and H (n = 17) groups, respectively, for the AVR cohort; for the MVR cohort, these estimates were 60 +/- 10% (n = 12) and 72 +/- 10% (n = 11), respectively, but these differences were not statistically significant (P = NS, Lee-Desu).After 10 years, there was no statistically significant difference in durability or other valve-related complications between the H and C-E aortic or mitral valves. Based on current information, the choice of a porcine bioprosthesis should be based on factors other than durability, including ease of implantation, hemodynamic performance, and cost.

A system has been developed for the nuclear magnetic resonance spectroscopic evaluation of cerebral high-energy phosphate levels during hypothermic total circulatory arrest and reperfusion by means of cardiopulmonary bypass in large animals. The use of intermittent hypothermic asanguineous cerebral perfusion, termed cerebroplegia, for the preservation of cerebral high-energy phosphates during a 2-hour period of hypothermic total circulatory arrest and reperfusion has been evaluated. Cardiopulmonary bypass was used to achieve deep hypothermia (12 degrees to 15 degrees C) during 2 hours of circulatory arrest and reperfusion. Juvenile sheep were divided into two groups. Group 1 animals (n = 8) (no cerebroplegia) served as the control group. In group 2 animals (n = 7), cerebroplegia was established by intermittent bilateral carotid artery infusion of a hypothermic oxygenated asanguineous cardioplegic solution. Nuclear magnetic resonance spectroscopy recorded changes in cerebral adenosine triphosphate, creatine phosphate, and intracellular pH. Adenosine triphosphate, creatine phosphate, and pH were higher in the group 2 animals for all points during the arrest period and until 60 minutes after reperfusion (p less than 0.05). Electroencephalographic activity returned after 36 minutes of reperfusion in group 2, but it did not return until 117 minutes in group 1 (p less than 0.05). In summary, cerebral high-energy phosphates and pH were maintained and the electroencephalographic signal returned more rapidly during circulatory arrest with the institution of cerebroplegia. These studies suggest that cerebroplegia is protective of the brain during circulatory arrest.

Background: Thermodilution coronary flow reserve (CFRthermo) IS a new technique for measuring coronary flow reserve (CFR) using a coronary pressure wire and based on the ability of the pressure transducer to also measure temperature changes. CFRthermois defined as the mean transit time of room temperature saline injected down the LAD at rest divided by the mean transit time at maximal hyperemla. Methods: In an open-chest pig model, CFRthermoin the left anterior descending (LAD) artery was measured and compared to flow reserve from a Doppler wire (CFR doppler), and an external flow probe placed around the LAD (CFRfkxv). In 6 pigs, CFR was measured by all 3 means in the normal LAD and after creation of an epicardial LAD stenosis. In order to determine the added effect of microvascular disease, measurements of flow reserve were also performed after disruption of the coronary microcirculation using embolized microspheres. lntracoronary papaverine (20 mg) was used to induce hyperemia. Methodr and Results: Twenty-three patients (age 52 * 8 years) were studied. A total of 129 PVs were assessed with AcuNav (Acuson) and 80 PVs with 9MHz (Boston Sci) ICE. After RF ablation, peak Doppler velocity at PV ostium increased from 52 * 17 to 74 t 24 cm/s and gradient increased from 1.2 * 0.7 to 2.4 c 1.4’ mmHg, *p < 0.01. Ablation also resulted I” an acute decrease in PV cross-sectional area (CSA) from 3.1 f 1.8 to 1.9 * 1 .I’ err?, increase in wall thickness from 0.7 f 0.2 to 1.6 f 0.7’ mm and loss of its normal motility throughout the cardiac cycle: %change decreased from 27 * 14% to 20 * 8%’ (Fig), ‘p < 0.01. Unablated PVs remained unchanged. Conclusion: RF ablation resulted in acute increases in PV flow velocity and wall thickness and decreases in CSA and motility, although no significant pulmonary stenosis was ’ observed. ICE provides.useful information about PV status in RF catheter ablation.

Background. We studied the efficacy and tolerability of combined immunosuppressive therapy with cyclosporine A microemulsion (Neoral) plus the macrolide SDZ RAD 40 ‐ 0 (2-hydroxyethyl) rapamycin (RAD) in a stringent cynomolgus monkey lung graft model in comparison with cyclosporine or SDZ RAD monotherapy. Methods. Thirty-nine cynomolgus monkeys received mixed lymphocyte reaction (MLR) mismatched unilateral lung transplants. Immunosuppressants were administered orally as single daily doses. The observation period was 28 days and follow-up included serial trough blood drug concentrations measured by high performance liquid chromatography/mass spectrometry, blood analyses, chest radiographs, open lung biopsies, as well as tissue drug concentrations and graft histology at necropsy. Results. Graft biopsies in monkeys treated with vehicle (n54), Neoral (day 1‐7: 150 mg/kg/day; day 8 ‐28: 100 mg/kg/day; n56; mean6SE trough level (MTL): 292617 ng/ml) or SDZ RAD monotherapy (1.5 mg/kg/ day; n56; MTL: 1561 ng/ml) showed severe rejection. Coadministration in two transplant monkeys of Neoral (150/100 mg/kg/day) and SDZ RAD (1.5 mg/kg/day) caused their early death. In both animals, SDZ RAD blood levels were more than 5-fold higher than under monotherapy (MTL: 82618 ng/ml). Simultaneous administration (n56) of Neoral (150/100 mg/kg/day; MTL: 217616 ng/ml) and SDZ RAD (0.3 mg/kg/day; MTL: 2462 ng/ml) improved graft outcome (mild rejection). Side effects included renal failure (n52) and seizures (n51). Three monkeys survived to day 28. In this group the MTL for cyclosporin was 143613 and for RAD 3863.Staggered treatment completely prevented rejection in four of six grafts. However, five of six monkeys had moderate to severe diarrhea. In a concentration-controlled trial of simultaneously administered Neoral and SDZ RAD in transplant monkeys (target SDZ RAD MTL: 20 ‐ 40 ng/ml; cyclosporine MTL: 100 ‐ 200 ng/ml) all six monkeys survived with improved drug tolerability and an average biopsy score of mild rejection. Conclusion. Combination of orally administered SDZ RAD and Neoral showed excellent immunosuppressive efficacy in a stringent lung transplant model. The drug interaction and the narrow therapeutic index of this drug combination required careful dose adjustments to optimize tolerability and efficacy.

Surveys were made of condensation nuclei, freezing nuclei, and water vapor concentrations in the exhaust wake of an F80 jet aircraft. Condensation nuclei concentrations were found to be maximum in a region of 50 to 75 ft aft of the tailpipe, with secondary maxima appearing at approximately 150 ft. No freezing nuclei were found, although observations indicated the possibility that they were present but inhibited by exhaust constituents.

Insulin inhibition of histamine-stimulated gastric secretion of H+, Cl−, K+, and water in unanesthetized dogs could not be reversed by the subsequent correction of hypoglycemia or prevented by the prevention of hypoglycemia. These findings suggested that inhibition by insulin was not related directly to hypoglycemia or to any of its homeostatic consequences. Further evidence for the direct action of insulin on the stomach was derived from inhibition of H+ and Cl− secretion in guinea-pig gastric mucosa in vitro in the presence of adequate glucose.

SummaryA high vitamin D intake 1, 500,000 units/kg of diet) severely decreased weight gain, caused necrosis and calcification of blood vessels and kidneys, and decreased the suspension stability of the blood of rats. Chondroitin sulfate A and the flavonoids (rutin and hesperidin) showed no effect on weight loss, serum cholesterol, tissue calcifications, or hematocrits, but returned the suspension stability of the blood towards normal.