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Biomedical subjects

M L Barr

Publications and source records attributed to M L Barr.

At least 37 records · Page 2Linked to original sources
PubMed1999

Sirolimus (rapamycin) potentiates cyclosporine in prevention of acute lung rejection.

BACKGROUND: Cyclosporine-based immunosuppressive regimens (INN: ciclosporin) in human lung transplantation continue to result in a high incidence of acute cellular rejection. We investigated the use of sirolimus, a macrolide with structural similarity to tacrolimus, as monotherapy and in combination with cyclosporine in a rodent lung transplant model. METHODS: Orthotopic left lung transplantation was performed in Lewis recipients from Brown-Norway donor rats with syngeneic Lewis-to-Lewis controls. Open biopsies were performed on postoperative day 7, and the severity of acute lung rejection was graded by a pathologist blinded to the protocol. RESULTS: All recipients survived despite the amount of acute rejection seen on examination of the biopsy tissue. Lewis-to-Lewis isografts demonstrated near normal pulmonary architecture. Allogeneic recipients receiving high-dose cyclosporine (25 mg/kg) monotherapy showed mild to moderate acute rejection with some perivascular focal interstitial infiltrates. Recipients receiving low-dose cyclosporine (5 mg/kg) monotherapy or low- or high-dose sirolimus (0.5 or 2.0 mg/kg, respectively) monotherapy demonstrated massive cellular infiltration leading to necrosis and infarction and could not be graded. However, the addition of low-dose sirolimus (0.5 mg/kg) to low-dose cyclosporine (5 mg/kg) demonstrated a significant potentiating immunosuppressive effect, and the addition of high-dose sirolimus (2.0 mg/kg) to low-dose cyclosporine (5.0 mg/kg) demonstrated an even greater effect, with rejection scores better than those obtained with high-dose cyclosporine monotherapy and similar to those obtained with isografts. CONCLUSIONS: This study demonstrates that low-dose sirolimus has a cyclosporine-sparing effect and that a higher dose of sirolimus in combination with cyclosporine strongly protects lung allografts from acute cellular rejection. These results suggest that sirolimus may be indicated as an adjunct to current cyclosporine-based immunosuppressive regimens in clinical lung transplantation.

Acute Disease↗
PubMed1999

A randomized, multicenter comparison of tacrolimus and cyclosporine immunosuppressive regimens in cardiac transplantation: decreased hyperlipidemia and hypertension with tacrolimus.

BACKGROUND: Tacrolimus-based immunosuppression seems safe and effective in liver and kidney transplantation. To assess the safety and efficacy of tacrolimus (TAC)-based immunosuppression after cardiac transplantation as well as the relative impact of tacrolimus on immunosuppression-related side effects such as hypertension and hyperlipidemia, we conducted a prospective, randomized, open-label, multicenter study of otherwise identical tacrolimus- and cyclosporine-based immunosuppressive regimens in adult patients undergoing cardiac transplantation. METHODS: Eighty-five adult patients (pts) at six United States cardiac transplant centers, undergoing their first cardiac transplant procedure, were prospectively randomized to receive either TAC-based (n = 39) or cyclosporine (CYA)-based (n = 46) immunosuppression. All pts received a triple-drug protocol with 15 pts (18%) receiving peri-operative OKT3 to delay TAC/CYA due to pre-transplant renal dysfunction. Endomyocardial biopsies were performed at Weeks 1, 2, 3, 4, 6, 8, 10, 12, 24, and 52. The study duration was 12 months. RESULTS: Patients were mostly male (87%) Caucasian (90%) with a mean age of 54 years and primary diagnoses of coronary artery disease (55%) and idiopathic dilated cardiomyopathy (41%). There were no significant demographic differences between groups. Patient and allograft survival were not different in the two groups. The probability and overall incidence of each grade of rejection, whether treated or not, and the types of treatment required did not differ between the groups. At baseline and through 12 months of follow-up, chemistry and hematology values were similar between the groups except serum cholesterol was higher in the CYA group at 3, 6, and 12 months (239 vs 205 mg/dL, 246 vs 191 mg/dL, 212 vs 186 mg/dL, respectively, p < 0.001). Likewise, LDL-cholesterol, HDL-cholesterol and triglycerides were significantly higher in the CYA group. More CYA patients received therapy for hypercholesterolemia (71% vs 41% at 12 months, p = 0.01). There were no significant differences in renal function, hyperglycemia, hypomagnesemia, or hyperkalemia during the first 12 months. More CYA patients developed new-onset hypertension requiring pharmacologic treatment (71% vs 48%, p = 0.05). The incidence of infection was the same for the two groups (2.6 episodes/pt/12 month follow-up). CONCLUSION: Tacrolimus-based immunosuppression seems effective for rejection prophylaxis during the first year after cardiac transplantation and is associated with less hypertension and hyperlipidemia and no difference in renal function, hyperglycemia or infection incidence when compared to cyclosporine-based immunosuppression.

Adult↗
PubMed1998

Photopheresis for the prevention of rejection in cardiac transplantation. Photopheresis Transplantation Study Group.

BACKGROUND: Photopheresis is an immunoregulatory technique in which lymphocytes are reinfused after exposure to a photoactive compound (methoxsalen) and ultraviolet A light. We performed a preliminary study to assess the safety and efficacy of photopheresis in the prevention of acute rejection of cardiac allografts. METHODS: A total of 60 consecutive eligible recipients of primary cardiac transplants were randomly assigned to standard triple-drug immunosuppressive therapy (cyclosporine, azathioprine, and prednisone) alone or in conjunction with photopheresis. The photopheresis group received a total of 24 photopheresis treatments, each pair of treatments given on two consecutive days, during the first six months after transplantation. The regimen for maintenance immunosuppression, the definition and treatment of rejection episodes, the use of prophylactic antibiotics, and the schedule for cardiac biopsies were standardized among all 12 study centers. All the cardiac-biopsy samples were graded in a blinded manner at a central pathology laboratory. Plasma from the subgroup of 34 patients (57 percent) who were enrolled at the nine U.S. centers was analyzed by polymerase-chain-reaction amplification for cytomegalovirus DNA. RESULTS: After six months of follow-up, the mean (+/-SD) number of episodes of acute rejection per patient was 1.44+/-1.0 in the standard-therapy group, as compared with 0.91+/-1.0 in the photopheresis group (P=0.04). Significantly more patients in the photopheresis group had one rejection episode or none (27 of 33) than in the standard-therapy group (14 of 27), and significantly fewer patients in the photopheresis group had two or more rejection episodes (6 of 33) than in the standard-therapy group (13 of 27, P=0.02). There was no significant difference in the time to a first episode of rejection, the incidence of rejection associated with hemodynamic compromise, or survival at 6 and 12 months. Although there were no significant differences in the rates or types of infection, cytomegalovirus DNA was detected significantly less frequently in the photopheresis group than in the standard-therapy group (P=0.04). CONCLUSIONS: In this pilot study, the addition of photopheresis to triple-drug immunosuppressive therapy significantly decreased the risk of cardiac rejection without increasing the incidence of infection.

Combined Modality Therapy↗
PubMed1998

Addition of aprotinin to organ preservation solutions decreases lung reperfusion injury.

BACKGROUND: Organ preservation injury is associated with endothelial cell damage, destabilization of mitochondrial and cell membranes, and the release of proteolytic enzymes. In addition to its well-known clinical effect of reducing perioperative blood loss, aprotinin has antiproteolytic and membrane-stabilizing properties. We hypothesized that adding aprotinin to Euro-Collins (EC) and University of Wisconsin (UW) solutions would decrease preservation injury in cultured endothelial cells and a whole organ rat lung model. METHODS: Bovine aortic endothelial cells were cultured and stored in the respective solution at 4 degrees C for 12 or 48 hours. Endothelial cell viability after storage was assessed by dimethylthiazole tetrazolium cytotoxicity assay. In the whole organ model, rat lungs were isolated, flushed with the respective solution, and stored at 4 degrees C for 6 or 12 hours. The lungs were ventilated with 100% O2 and reperfused with fresh blood. Alveolar-arterial O2 difference, O2 tension, capillary filtration coefficient, and compliance were determined. RESULTS: Endothelial cell viability was optimized with the addition of aprotinin to EC and UW at a dose of 150 KIU/mL (0.02 mg/mL). In the isolated perfused lung model, after 6 hours of ischemic storage, aprotinin-enhanced (100 KIU/mL [0.014 mg/mL]) EC and UW decreased alveolar-arterial O2 difference, increased O2 tension, and decreased capillary filtration coefficient compared with EC and UW alone. After 12 hours of ischemic storage, aprotinin-enhanced EC and UW decreased alveolar-arterial O2 difference, increased O2 tension, decreased capillary filtration coefficient, and increased compliance compared with EC and UW alone. CONCLUSIONS: The addition of aprotinin to EC and UW solutions increases endothelial cell viability in hypoxic cold storage conditions. In terms of whole organ function, aprotinin improves lung preservation as demonstrated by increased oxygenation and compliance, and decreased capillary permeability. This study is clinically applicable as there is already extensive experience with the use of aprotinin in heart and lung transplant recipients, in addition to its routine use in conventional cardiac operations.

Adenosine↗
PubMed1998

Addition of a mast cell stabilizing compound to organ preservation solutions decreases lung reperfusion injury.

OBJECTIVE: Research in lung transplant preservation has generally focused on free radicals and enzyme release from neutrophils, parenchymal cells, macrophages, and endothelium. The lung has a large resident population of mast cells that, when activated, release potent inflammatory mediators. We hypothesized that adding an inhibitor of mast cell degranulation, lodoxamide tromethamine (10 micromol/L), to Euro-Collins and University of Wisconsin preservation solutions, would decrease lung preservation injury. METHODS: Rat lungs were isolated, flushed with the respective solution, and stored at 4 degrees C for 6 or 12 hours. The lungs were reperfused with fresh blood and ventilated with 100% oxygen. Alveolar-arterial oxygen difference, oxygen tension, capillary filtration coefficient, and compliance were determined. RESULTS: After 6 hours of ischemic storage: lodoxamide tromethamine-enhanced Euro-Collins solution decreased alveolar-arterial oxygen difference from 539 to 457 (p = 0.004), increased oxygen tension from 119 to 205 mm Hg (p = 0.006), and decreased capillary filtration coefficient from 3.9 to 2.0 (p < 0.001); lodoxamide tromethamine-enhanced University of Wisconsin solution decreased alveolar-arterial oxygen difference from 546 to 317 (p < 0.001), increased oxygen tension from 166 to 335 mm Hg (p < 0.001), and decreased capillary filtration coefficient from 3.0 to 1.7 (p < 0.001). After 12 hours of ischemic storage, lodoxamide tromethamine-enhanced Euro-Collins solution decreased alveolar-arterial oxygen difference from 588 to 485 (p < 0.001), increased oxygen tension from 100 to 161 mm Hg (p = 0.012), decreased capillary filtration coefficient from 6.2 to 2.6 (p < 0.001), and increased compliance from 0.12 to 0.21 (p < 0.001); lodoxamide tromethamine-enhanced University of Wisconsin solution decreased alveolar-arterial oxygen difference from 478 to 322 (p < 0.001), increased oxygen tension from 214 to 335 mm Hg (p < 0.001), decreased capillary filtration constant from 4.2 to 2.0 (p < 0.001), and increased compliance from 0.20 to 0.25 (p < 0.001). CONCLUSIONS: Addition of lodoxamide tromethamine to Euro-Collins or University of Wisconsin solution results in a marked decrease in lung reperfusion injury as demonstrated by increased oxygenation, decreased microvascular permeability, and increased compliance. These results are relevant as Euro-Collins and University of Wisconsin solutions are the most common clinically used lung preservation solutions. This study also highlights the deleterious role of resident mast cells in preservation injury.

Animals↗
PubMed1998

Living donor lobar lung transplantation: the pediatric experience.

Living donor (LD) lobar lung transplantation is now an accepted alternative to cadaveric lung transplantation in selected patients with end-stage lung disease. This study reviews the Childrens Hospital Los Angeles LD experience of 17 patients (mean 13.2 +/- 2.7 yrs; range 9.3-18.5 yrs). 12 LD patients had end-stage cystic fibrosis, 4 had primary pulmonary hypertension, and 1 child had bronchiolitis obliterans. LD candidates must meet the same criteria as for cadaveric lung transplant candidates. Donor candidates are rigorously screened (physically and psychologically) prior to acceptance for lobectomy. LD patients receive the same triple immunosuppression regimen as our cadaveric recipients (prednisone, cyclosporine/FK506, and azathioprine/mycophenolate). Comparison of rejection episodes, incidence of bronchiolitis obliterans, pulmonary function tests, exercise stress tests, and cardiac catheterization data was made between LD and cadaveric lung transplantation (CL) pediatric recipients. Donor outcomes were also reviewed. In our pediatric program, the 1-year survival rate for LD recipients is currently 81%, which compares favorably with the ISHLT average of 70% for pediatric transplant patients. The incidence of rejection is about the same for LD and CL recipients, but the episodes are less severe for pediatric LD patients. There have been no histological cases of bronchiolitis obliterans syndrome in our LD recipients. Although there have been questions as to whether transplanted lobes can supply comparable pulmonary reserve to whole cadaveric lungs, the lung volumes (TLC and VC), expiratory flow rates, maximal exercise stress tests, and pulmonary artery pressures (no evidence of pulmonary hypertension) in LD patients are not significantly different to CL recipients in our institution. Besides pain from the thoracotomy, the donors have a decrease of 16% (right lower lobe donor) and 18% (left lower lobe donor) in their vital capacity. Otherwise, there have been no major complications to the donors and most have resumed their usual activities. Based on outcomes, pulmonary function tests, exercise stress tests, and hemodynamic studies as well as low donor morbidity, living donor double lobar lung transplantation is a viable alternative to cadaveric lung transplantation in selected pediatric patients with end-stage lung disease.

Adolescent↗
PubMed1997

Experience with living-donor lobar transplantation for indications other than cystic fibrosis.

OBJECTIVE: Since development of a living donor bilateral lobar transplantation protocol for patients with cystic fibrosis, our indications have expanded to include recipients with other diagnoses. METHODS: We report on our experience in eight patients with primary pulmonary hypertension, postchemotherapy pulmonary fibrosis, bronchopulmonary dysplasia, idiopathic pulmonary fibrosis, and obliterative bronchiolitis. The average age of the eight patients was 19.1 years (range 9 to 40). The mean preoperative carbon dioxide tension for the four patients who did not have primary pulmonary hypertension was 92 mm Hg (range 64 to 120 mm Hg), and the two patients with pulmonary fibrosis were intubated (one on high-frequency jet ventilation). Each recipient received a right lower lobe (n = 7) or middle lobe (n = 1) and a left lower lobe (n = 8) from a total of 16 donors representing various combinations of the recipient's family (n = 15) and an unrelated friend (n = 1). RESULTS: With an average follow-up of 1 year the overall survival is 75%. For the five patients followed up for at least 1 year, mean forced vital capacity was 80.6%, forced expiratory volume in 1 second was 75.6%, mid-forced expiratory flow was 64%, and diffusing lung capacity corrected for alveolar volume was 73% of predicted. For those patients with primary pulmonary hypertension, preoperative hemodynamics revealed mean pressures as follows: blood pressure 84.8 mm Hg, right atrial pressure 7.8 mm Hg, pulmonary artery pressure 71.3 mm Hg, pulmonary capillary wedge pressure 9.5 mm Hg, cardiac index 2.9 L/min per square meter, and pulmonary vascular resistance index 22.8 Wood units. Postoperative hemodynamics revealed a mean blood pressure of 84.3 mm Hg, right atrial pressure of 2.7 mm Hg, pulmonary artery pressure of 16 mm Hg, pulmonary capillary wedge pressure of 7.3 mm Hg, cardiac index of 4.2 L/min per square meter, and pulmonary vascular resistance index of 1.9 Wood units. CONCLUSIONS: Early results of living-donor bilateral lobar transplantation for diseases other than cystic fibrosis have resulted in satisfactory survival and pulmonary function. Additionally, patients with severe primary pulmonary hypertension have had dramatic normalization of their hemodynamics despite the limited amount of lung tissue transplanted. We believe that the data from this small cohort experience compares favorably with our larger series with cystic fibrosis and supports an expanded role for living-donor lobar transplantation in patients with alternate indications.

Adult↗
PubMed1996

Safe application of diagnostic laparoscopy during biventricular assistance.

We performed diagnostic laparoscopy in a patient who was critically unstable while on an ABIOMED BVS 5000 biventricular assist system. A relatively unique feature of the ABIOMED is the venous return being dependent only on gravity and the drawing force of venous return being the height of the inflow cannula compared with the level of the ABIOMED blood pump assembly; this did not preclude the use of pneumoperitoneum necessary for laparoscopy. The safe application of diagnostic laparoscopy in patients on a ventricular assist device is of importance in an era of increasing use of these devices and the increased potential for intraabdominal complications in this population.

Abdomen, Acute↗
PubMed1996

Living-donor lobar lung transplantation experience: intermediate results.

OBJECTIVE: Living-donor lobar lung transplantation offers an alternative for patients with a life expectancy of less than a few months. We report on our intermediate results with respect to recipient survival, complications, pulmonary function, and hemodynamic reserve. METHODS: Thirty-eight living-donor lobar lung transplants were performed in 27 adult and 10 pediatric patients for cystic fibrosis (32), pulmonary hypertension (two), pulmonary fibrosis (one), viral bronchiolitis (one), bronchopulmonary dysplasia (one), and posttransplantation obliterative bronchiolitis (one). Seventy-six donors underwent donor lobectomies. RESULTS: There were 14 deaths among the 37 patients, with an average follow-up of 14 months. Predominant cause of death was infection, consistent with the large percentage of patients with cystic fibrosis in our population. The overall incidence of rejection was 0.07 episodes/patient-month, representing 0.8 episodes/patient. Postoperative pulmonary function testing generally showed a steady improvement that plateaued by postoperative months 9 to 12. Fourteen patients who were followed up for at least 1 year underwent right heart catheterization; pressures and pulmonary vascular resistances were within normal ranges. Bronchiolitis obliterans was definitively diagnosed in three patients. Among the 76 donors, complications in the postoperative period included postpericardiotomy syndrome (three), atrial fibrillation (one), and surgical reexploration (three). CONCLUSIONS: We believe that these data support an expanded role for living-donor lobar lung transplantation. Our intermediate data are encouraging with respect to the functional outcome and survival of these critically ill patients, who would have died without this option.

Adolescent↗
PubMed1996

Orbital myositis, vitiligo, and giant cell myocarditis.

Giant cell myocarditis is a rare idiopathic inflammatory heart disease characterized histologically by multinucleated giant cells, and clinically by rapid progressive heart failure, arrhythmias, or sudden death, often within hours to days of initial symptoms. There are two previously reported cases of giant cell myocarditis with idiopathic orbital myositis. We report a similar case in a patient who also had vitiligo, a diagnostic endomyocardial biopsy, and survival because of a cardiac transplant. Giant cell myocarditis should be monitored for in the course of inflammatory orbital myopathy because of its life-threatening fulminant course.

Adult↗
PubMed1996

Bilateral lobar transplantation utilizing living related donors.

As the recipient list for patients requiring lung transplantation continues to increase, cadaveric donor lung availability has remained static. Our experience with utilizing lobes from living related donors for bilateral pulmonary transplantation in 20 patients has yielded a 75% survival at 1 year follow-up. Morbidity and mortality have been predominately due to infection. Rejection episodes have been mild and unilateral and have responded to augmented corticosteroids. Pulmonary function tests in the recipients tend to improve steadily during the first year postoperatively, and the patients have excellent functional capacity. There have been no significant complications in the donors. On the basis of our clinical experience, we have found that bilateral lobar transplantation utilizing living related donors has resulted in organ availability that can be lifesaving in critically ill patients and can provide a good alternative in certain noncritical, deteriorating patients.

Adolescent↗
PubMed1996

Immunomodulation in transplantation with photopheresis.

Photopheresis is a technique in which peripheral blood mononuclear cells, in the presence of a photoactivatable compound, are exposed extracorporeally to ultraviolet A light and reinfused, inducing a host autoregulatory immune response. Experimental work and ongoing clinical studies are helping to define the role of this novel, safe, and non-toxic immunomodulating technology in the field of transplantation.

Animals↗
PubMed1995

Increased early mortality in women undergoing cardiac transplantation.

BACKGROUND: To evaluate factors that explain sex differences affecting mortality after cardiac transplantation, a retrospective analysis of adult patients undergoing orthotopic cardiac transplantation was undertaken at the Columbia-Presbyterian Medical Center. METHODS AND RESULTS: The study population consisted of 379 patients (75 women, 304 men) > or = 18 years of age who survived for > or = 48 hours after undergoing orthotopic cardiac transplantation between March 1985 and March 1992. The following were analyzed: incidence of death and treated rejection episodes, donor and recipient cytomegalovirus (CMV) matches, use of OKT3 induction therapy, and donor and recipient HLA mismatches. Women 49 +/- 12 years old and men 47 +/- 12 years old were characterized by differences in race and diagnosis. Women were more likely to be nonwhite (P < .01) and have idiopathic cardiomyopathy than were men (P < .01). A trend toward an increase in first-year rejection frequency was seen in women compared with men (P = .08). Overall actuarial survival was significantly reduced in women after transplantation (P < .05). At 36 months, female actuarial survival was 64 +/- 7% versus 76 +/- 3% for men (P < .05). The majority of patients in this study did not receive CMV prophylaxis. Univariate analysis revealed that only CMV(+) donor status and the use of OKT3 induction therapy affected survival in women. Multivariate analysis revealed a marked reduction in survival in female recipients of CMV(+) donors given OKT3 induction therapy. At 36 months, only 25% of women were still alive compared with 86% of women with neither risk factor (P < .001). Even without OKT3 induction there was markedly reduced survival in women with mismatched CMV status, ie, CMV(-) recipients of CMV(+) donors; 17% survival after 36 months versus 86% in women who were CMV(+) recipients (P < .05). Although at this institution during the study time period, CMV prophylaxis was not routinely employed and OKT3 induction was selectively used in higher-risk patients, conclusions regarding differences in outcome that are sex dependent are valid. CONCLUSIONS: (1) Women are at risk for reduced actuarial survival up to 3 years after cardiac transplantation. (2) Univariate analysis shows that women are selectively at risk for death when receiving hearts from CMV(+) donors and after receiving OKT3 induction therapy. (3) Multivariate analysis reveals that women are at even greater risk for death when receiving hearts from CMV(+) donors in conjunction with OKT3 induction therapy. (4) In the absence of OKT3 use, the greatest risk of death occurs in CMV(-) women transplanted with CMV(+) donor hearts. (5) When female to male survival curves are compared, factors that influenced survival in women did not appear to be problematic in men.

Actuarial Analysis↗
PubMed1995

Surgical management of cardiac pheochromocytoma. Resection versus transplantation.

OBJECTIVE: The authors review their experience and that of others who have reported cases in the literature on the surgical management of cardiac pheochromocytomas. SUMMARY BACKGROUND DATA: Cardiac pheochromocytomas are rare cathecolamine-producing tumors that can be densely adherent to myocardium. Because resection can be associated with significant morbidity, we sought to determine the best mode of treatment for these difficult tumors. METHOD: The authors reviewed the experience for management of cardiac pheochromocytomas in their two institutions and those reported in the literature. Follow-up was available for 21 of 26 patients up to 9 years after resection. RESULTS: Twenty-five patients had reconstruction of the native heart; five (20%) died intraoperatively from hemorrhage, one (4%) died postoperatively from sepsis, three (12%) sustained myocardial infarction, one (4%) required a mitral valve replacement, and three (12%) had incomplete resections, two of whom subsequently developed metastatic disease and died. One patient, thought to be a high risk for resection, received an orthotopic heart transplantation. CONCLUSIONS: Surgical resection of cardiac pheochromocytomas can be performed successfully. However, resection of lesions that aggressively invade adjacent myocardium is associated with significant mortality and inadequate control of the neoplasm. Cardiac transplantation should be available as an option before embarking on resection, and it should be performed if mandated by intraoperative findings.

Adult↗