Expression of endothelin-1 in the lungs of patients with pulmonary hypertension

BACKGROUND

Pulmonary hypertension is characterized by an increase in vascular tone or an abnormal proliferation of muscle cells in the walls of small pulmonary arteries. Endothelin-1 is a potent endothelium-derived vasoconstrictor peptide with important mitogenic properties. It has therefore been suggested that endothelin-1 may contribute to increases in pulmonary arterial tone or smooth-muscle proliferation in patients with pulmonary hypertension. We studied the sites and magnitude of endothelin-1 production in the lungs of patients with various causes of pulmonary hypertension.

METHODS

We studied the distribution of endothelin-1-like immunoreactivity (by immunocytochemical analysis) and endothelin-1 messenger RNA (by in situ hybridization) in lung specimens from 15 control subjects, 11 patients with plexogenic pulmonary arteriopathy (grades 4 through 6), and 17 patients with secondary pulmonary hypertension and pulmonary arteriopathy of grades 1 through 3.

RESULTS

In the controls, endothelin-1-like immunoreactivity was rarely seen in vascular endothelial cells. In the patients with pulmonary hypertension, endothelin-1-like immunoreactivity was abundant, predominantly in endothelial cells of pulmonary arteries with medial thickening and intimal fibrosis. Likewise, endothelin-1 messenger RNA was increased in the patients with pulmonary hypertension and was expressed primarily at sites of endothelin-1-like immunoreactivity. There was a strong correlation between the intensity of endothelin-1-like immunoreactivity and pulmonary vascular resistance in the patients with plexogenic pulmonary arteriopathy, but not in those with secondary pulmonary hypertension.

CONCLUSIONS

Pulmonary hypertension is associated with the increased expression of endothelin-1 in vascular endothelial cells, suggesting that the local production of endothelin-1 may contribute to the vascular abnormalities associated with this disorder.

Video-assisted minithoracotomy versus muscle-sparing thoracotomy for performing lobectomy

We prospectively analyzed the outcome of lobectomy in a cohort of 67 patients. Operative time, postoperative pain, pulmonary function, and early outcome were compared between the patients undergoing video-assisted techniques (n = 44) and those undergoing standard muscle-sparing procedures (n = 23). Pain was quantified daily throughout the first week using the visual analog scale. The forced expiratory volume in 1 second and the forced vital capacity were measured at days 2, 4, and 8 postoperatively. The operative time was significantly longer (p < 0.02) and the postoperative pain was significantly less (p < 0.006) in the group undergoing video-assisted procedures. Pain-related morbidity, the mean duration of air leaks, the duration of chest tube placement, and the hospital stay were all less in the video-assisted group, but the differences did not reach statistical significance. However, the impairment in pulmonary function and the overall morbidity were identical for the two groups. Based on our findings, we conclude that video-assisted minithoracotomy is a safe and reliable approach for performing lobectomies, and that the decreased postoperative pain associated with this minimally invasive approach does not result in preserved pulmonary function and significantly reduced morbidity when compared with a muscle-sparing thoracotomy.

Airway complications in lung transplantation

This article reviews the literature on airway healing after lung transplantation. From a historical point of view, this has been the Achilles' heel of lung transplantation through two decades, from the first attempt at single-lung transplantation in 1963 to the clinical successes in the early 1980s. The overall incidence of lethal airway complications is estimated to be 2% to 3%, whereas that of late stricture is 7% to 14%. Comparison of experiences has been difficult without a universal classification; a new classification for airway and anastomotic complications and healing is proposed. Ischemia appears to be the most important factor influencing airway healing. Low-pressure collateral bronchial blood flow from the pulmonary artery may be affected by low cardiac output, reperfusion edema, or rejection; mucosal injury may be further increased by prolonged positive-pressure ventilation. Good bronchial healing appears to be possible without a protective wrap and with early use of steroids. The management of bronchial complications is challenging and requires endoscopic skills including knowledge of endobronchial laser photocoagulation and stent insertion techniques.

Expression of nitric oxide synthase in the human nasal mucosa

The nasal mucosa plays an important role in defense of the lung against harmful agents. It has been suggested that this is partly mediated by the production of nitric oxide (NO). We have investigated the localization of the messenger ribonucleic acids (MRNAs) for human endothelial NO synthase (Type III NOS) and inducible NO synthase (Type II NOS) and the immunoreactivities of these enzymes in human nasal mucosa by immunohistochemistry, in situ hybridization, and reduced nicotinamide adenine diphosphate (NADPH) diaphorase histochemistry. Inferior nasal turbinates were obtained from 27 patients at the time of surgery for local disease. Strong immunostaining for Type III NOS was localized to vascular endothelium, surface epithelium, and submucosal glands in all subjects. Moderate immunostaining for Type II NOS was seen in surface epithelium; glandular, inflammatory, and vascular endothelial cells; and smooth-muscle cells in the specimens from patients with chronic rhinitis only. In situ hybridization showed expression of the mRNA for Type III NOS in similar sites to those shown by immunohistochemistry, whereas the mRNA for Type II NOS was predominantly localized to inflammatory cells. The sites of NOS expression were further confirmed by NADPH histochemical staining. These findings demonstrate the cellular expression of NOS in the human nasal mucosa and suggest a possible role for Types II and III NO synthase in the regulation of blood flow, nasal secretion, and ciliary movement in health and disease.

Arterial graft patency in coronary artery bypass grafting: what do we really know?

BACKGROUND

With increasing use of beating heart techniques for bypass of the left anterior descending coronary artery with the left internal mammary artery (LIMA), appropriate concerns have been raised of whether graft patency by these techniques compares favorably with conventional, arrested heart techniques.

METHODS

All published articles that examine outcome efficacy of the LIMA graft to the left anterior descending coronary artery were reviewed. Because angiography has been considered the "gold standard," only those studies that included angiographic follow-up were analyzed.

RESULTS

From 1972 through 1998, there have been 37 peer-reviewed publications that examined outcomes of LIMA grafting in conventional coronary bypass grafting, of which 27 contained angiographic follow-up data. The completeness of angiographic follow-up was variable, but early graft patency (< or =1 month) in studied patients ranged between 94% and 99%. Late graft patency (up to 15 years) ranged from 51% to 98%. Five recent series of minimally invasive direct coronary artery bypass grafting that contained LIMA graft patency data show early graft patency rates between 91% and 99%.

CONCLUSIONS

Meaningful comparison of LIMA graft patency between arrested heart, conventional coronary artery bypass grafting, and minimally invasive direct coronary artery bypass grafting is difficult; however, early graft patency by both techniques can confidently be stated as being 90% or greater.

Maximal exercise capacity and peripheral skeletal muscle function following lung transplantation

BACKGROUND

There have been many suggestions that diminished exercise capacity in patients that have undergone lung transplantation is due, in part, to peripheral muscle dysfunction, brought on by either detraining or immunosuppressive therapy. There is limited data quantifying skeletal muscle function in this population, especially in those more than 18 months post-procedure. The present study sought to quantitate skeletal muscle function and cardiopulmonary responses to graded exercise in 19 lung transplant recipients, 15 of which were mostly more than 18 months post-procedure.

METHODS

Ten single- (SLT) and 9 double-lung transplantation (DLT) underwent anthropometric measures and performed expiratory spirometry, whole body plethysmography to assess lung volumes, static maximal mouth pressures to assess respiratory muscle strength, progressive exercise testing on a cycle ergometer (with cardiac output measurements being performed every second workload) and isokinetic cycling to assess peripheral muscle power and work capacity.

RESULTS

The DLT group was younger than the SLT group (23.0 [21.0-32.0] vs 47.5 [43.0-55.0] median [interquartile range], p < .05) with no differences in height, weight, or BMI. Despite the DLT group having significantly better spirometric values (FEV1: 86% vs 56.5% median) and less airtrapping (RV/TLC: 30% vs 53.5%), both groups were equally limited in exercise capacity (Wmax)(38.0 percent predicted [30.0-65.0] vs 37.5 percent predicted [30.0-44.0], SLT vs DLT), leg power (76.1 percent predicted [53.8-81.4] vs 69.0 percent predicted [58.3-76.0]) and leg work capacity (63.3 percent predicted [34.7-66.8] vs 38.4 percent predicted [27.5-57.3]). This lack of difference in performance persisted when the analysis was limited to those more than 18 months post-procedure. Respiratory muscle strength was also not different for the two groups, and was within normal limits. Wmax was best correlated with leg work capacity (r = .84), but also with leg power, RV/TLC, FEV1 (r = .49, -.52, .58). When normalized for age, height, and sex, percent predicted Wmax only correlated with percent predicted leg work capacity (r = .58). Cardiac output was appropriate for the work performed.

CONCLUSIONS

We conclude that peripheral skeletal muscle work capacity is reduced following lung transplantation and mostly responsible for the limitation of exercise performance. While the causes of muscular dysfunction have yet to be clarified, the preservation of respiratory muscle strength with the concomitant reduction in leg power and work capacity suggests that most of the muscular dysfunction post-transplantation is attributable to detraining.

Video-assisted thoracic surgery: has technology found its place?

BACKGROUND

Since the introduction of minimally invasive surgical techniques in thoracic surgery in 1990, video-assisted thoracic surgery (VATS) has become the approach for many thoracic operations. The role of VATS has slowly evolved but has not been clearly defined. To better understand the role of VATS, we undertook a survey of practicing thoracic surgeons.

METHODS

A questionnaire was sent to members of the General Thoracic Surgery Club asking the role of VATS in their practice and their opinions regarding appropriate applications, advantages, and limitations of the approach.

RESULTS

Two hundred of the 229 members (87.3%) responded to the questionnaire. In this largely academic (66.3%) group of thoracic surgeons, 72% of whom had more than 10 years experience in general thoracic surgery, VATS was the preferred approach (> 50% response) for the management of pleural disease, lung biopsy, recurrent pneumothorax, and sympathectomy. A majority of respondents thought that VATS was an acceptable approach for the diagnosis of the indeterminate pulmonary nodule and of anterior and posterior mediastinal masses, and for the management of early empyema, clotted hemothoraces, secondary pneumothorax, limited lung cancer treatment, and benign esophageal disease. Video-assisted thoracic surgery was thought to be unacceptable or investigational by a majority for thymectomy, lobectomy, and lung volume reduction operations. Video-assisted thoracic surgery still represents only a small portion of the thoracic procedures performed, but there is a gradual increase in its rate of use, although 38.1% expressed concern regarding overuse. The main limitation was thought to be in the management of oncologic disease.

CONCLUSIONS

It appears that VATS is a valuable addition to the practice of thoracic surgery, but significant limitations exist. Although there appear to be many specific indications defined, there is still a significant evolutionary component.

Computer-assisted telemanipulation: an enabling technology for endoscopic coronary artery bypass

BACKGROUND

The ultimate objective of minimally invasive coronary artery bypass grafting is to perform the anastomosis totally endoscopically. In this feasibility study, we examined the potential of performing coronary artery bypass grafting with the use of computer-assisted telemanipulation technology.

METHODS

Intuitive Telemanipulation Technology (Intuitive Surgical, Mountain View, CA) was used to perform an arterial graft to left anterior descending coronary artery anastomosis in an ex vivo on-bench swine heart model. The degree of difficulty in performing the anastomosis, intraoperative events, duration of the anastomosis, and its quality were determined.

RESULTS

Anastomosis was performed with relative facility, in a range of 10.7 to 17.4 minutes (mean +/- standard deviation, 14.6 +/- 2.6 minutes). All anastomoses were patent and of good quality except one, which had 30% narrowing of its heel.

CONCLUSIONS

We conclude that Intuitive Telemanipulation Technology may in the future permit the performance of quality totally endoscopic coronary artery anastomosis with facility and acceptable time.

Double-lung transplantation in mechanically ventilated patients with cystic fibrosis

Many lung transplant programs consider ventilator dependence as a contraindication for transplantation. Among 54 patients in whom bilateral lung transplantations for cystic fibrosis were performed by the Joint Marseille-Montreal Lung Transplant Program, 10 were ventilator dependent. Three of them died in the early postoperative period (30%): 2 as a result of cerebral anoxia and sepsis, 1 of Pseudomonas cepacia pneumonia. Two patients died at 15 and 19 months after transplantation of obliterative bronchiolitis and secondary bacterial pneumonitis. Another 2 patients in whom obliterative bronchiolitis developed underwent retransplantation with a heart-lung block; 1 of those was operated on at 12 months and is well at 29 months after his initial transplantation; the second was operated on at 34 months and died of primary graft failure. Three other patients are alive and well at 3, 11, and 14 months after transplantation. Actuarial survival at 1 year was 70%. The postoperative course and the infectious and rejection complications were no different from those in patients who underwent transplantation while spontaneously breathing. Obliterative bronchiolitis developed in 66% of patients at risk (2 of 6 patients surviving more than 6 months). We conclude that transplantation in mechanically ventilated patients with cystic fibrosis is not associated with an increase in morbidity or mortality after bilateral lung transplantation. Long-term survival, as in patients who undergo transplantation while spontaneously breathing, is limited by the development of obliterative bronchiolitis.

Double-lung transplantation for cystic fibrosis. The Cystic Fibrosis Transplant Study Group

One hundred twenty cystic fibrosis patients were accepted for transplantation. Twenty-five patients underwent double-lung transplantation. Twenty-five patients died awaiting transplantation (20.6%). There were 13 female and 12 male patients. Their mean age was 28 years (range, 7 to 34 years), and mean percentage ideal body weight was 76% (range, 58.5% to 91.9%). Most patients were hypoxic and hypercarbic. Two patients underwent tracheal anastomosis, 15 had en bloc bronchial anastomoses, and 8 had sequential single-lung transplants. Operative mortality was 16%; all deaths were related to bleeding from extensive adhesions. Actuarial survival at 1 year was 64%. Rejection and infection were frequent during the first month and decreased thereafter. Airway complications occurred in 5 patients but were amenable to laser therapy and stenting. We conclude that double-lung transplantation is an acceptable modality for the treatment of cystic fibrosis patients with end-stage lung disease. It may be a better alternative to heart-lung transplantation considering the paucity of thoracic organ donors.

Robotic computer-assisted telemanipulation enhances coronary artery bypass

OBJECTIVES

Totally endoscopic coronary artery bypass grafting depends greatly on perfecting the anastomosis. We tested a new computer-assisted telemanipulation robot (Intuitive Surgical Inc, Mountain View, Calif) in performing endoscopic coronary bypass.

METHODS

On-bench anastomoses of the porcine arterial graft to the left anterior descending coronary artery were performed with both direct visualization and conventional surgical instruments (group I), endoscopic 3-dimensional visualization and current endoscopic surgical instruments (group II), direct visualization and endoscopic instruments (group III), 3-dimensional endoscopic visualization and conventional surgical instruments (group IV), and telemanipulation robotic with 3-dimensional endoscopic visualization (group V). Anastomoses (n = 6 in each group) were assessed for time (minutes), quality (good = 3, fair = 2, poor = 1), technical difficulty (easy-difficult: 1-4), and patency (100% = 1, >50% = 2, <50% = 3).

RESULTS

Anastomotic time was significantly longer in groups II and III than in groups IV and V (P </=.02). Patency was comparable in all groups.

CONCLUSION

Telemanipulation technology may enhance the performance of totally endoscopic coronary artery anastomosis. The facility and time of an Intuitive telemanipulation anastomosis is comparable with that of a conventional anastomosis created under direct vision.

Intraoperative transthoracic ultrasonographic localization of occult lung lesions

During video-assisted thoracoscopic operations, identification of small peripheral lung nodules can be challenging. We report the use of intraoperative intrathoracic ultrasonography for localization of lung tumors before resection in 2 patients.

Prolonged ischemia is associated with more pronounced rejection in the lung allograft

BACKGROUND

Previously it was found that ischemia-reperfusion injury in a left lung autotransplantation model could be a minor inducer of major histocompatibility complex (MHC) class II antigen expression. Thus, we hypothesized that prolonged ischemic times may result in increased expression of MHC class II antigens and predispose the lungs to the development of acute rejection early after transplantation.

METHODS

Twenty conditioned dogs underwent single left lung allotransplantation. Donor lungs were subjected to 4 or 24 hours (n = 10 each) of cold ischemia. Open lung biopsies, bronchoalveolar lavage fluid, and blood samples were taken preoperatively and at various intervals up to 1 week after transplantation. Lung biopsy specimens were examined histologically for MHC class II expression and graded for acute rejection. Bronchoalveolar lavage fluid and plasma were analyzed for cytokines interleukin-2 and interferon-gamma.

RESULTS

In the 4-hour ischemia group, there was mild diffuse staining of the bronchial epithelium and cellular infiltrate for MHC class II antigens after 1 week with subsequent grade 1-2 rejection. In the 24-hour ischemia group, MHC expression after 1 week revealed strong diffuse staining of bronchial epithelium, vascular endothelium, and cellular infiltrates with a significantly higher grade of rejection. Interleukin-2 and interferon-gamma significantly increased in BAL fluid early after transplantation in both groups.

CONCLUSIONS

Ischemic injury may predispose the lung allograft to the development of acute rejection, in part, through the upregulation of MHC class II antigen expression and the local release of cytokines.

Inhibition of cyclooxygenase-2 improves cardiac function in myocardial infarction

Induction of cyclooxygenase-2 (COX-2) in ischemic myocardium is thought to increase the production of proinflammatory prostanoids and contribute significantly to the ischemic inflammation. Left ventricular myocardial infarction (MI) was created by ligating the left coronary artery in Lewis rats. Hemodynamic measurements at 4 weeks showed better cardiac function in the group treated with a selective COX-2 inhibitor (DFU; 5 mg/kg/day) for 2 weeks after induction of MI compared to the vehicle treated group. These results suggest that induction of COX-2 contributes to myocardial dysfunction, and that selective inhibition of COX-2 could constitute an important therapeutic target for the treatment of MI.

Safe and effective method of stabilization for coronary artery bypass grafting on the beating heart

BACKGROUND

There is an emerging interest in performing coronary artery bypass grafting on the beating heart. This study examines the efficacy and safety of two types of coronary artery stabilizers developed to perform coronary artery bypass grafting on the beating heart.

METHODS

Four dogs underwent left internal mammary artery to left anterior descending artery anastomosis using a retractor-fixed stabilizer. Measurements of hemodynamic indices and range of motion of the targeted arteriotomy were done before and after application of the stabilizers. Patency of the anastomosis was evaluated by angiography. To clinically validate the safety of this stabilizer, we collected data on 150 patients from centers that had access to the retractor-fixed stabilizer.

RESULTS

All animals survived the procedure with no ischemic changes or hemodynamic alterations. A significant reduction in range of motion (mm) of the left anterior descending coronary artery was achieved after application of the stabilizers. Angiographic studies showed good anastomotic patency. Histologic examination showed no myocardial injury. Patient data revealed successful completion of the anastomosis, with conversion to sternotomy or cardiopulmonary bypass in 1 patient each. Intraoperative and postoperative myocardial infarctions occurred in 1 patient each, with one in-hospital death.

CONCLUSIONS

Significant stabilization of targeted coronary arteries allowing the performance of safe and reliable anastomosis on a beating heart can be achieved using the stabilizer.

Postthoracotomy pulmonary function: a comparison of epidural versus intravenous meperidine infusions

It has remained unclear whether epidural opioid analgesia permits better recovery of postthoracotomy pulmonary function than an optimal method of systemic opioid administration. Lumbar epidural meperidine infusions were compared with intravenous patient-controlled analgesic (PCA) meperidine infusions in a prospective randomized unblinded study for 72 hours postthoracotomy. Before induction of general anesthesia, patients received a bolus of meperidine, 1 mg/kg, and an infusion of meperidine, 0.33 mg/kg/hr, was started via either a lumbar epidural or intravenous catheter. Postoperatively, the meperidine infusion rates were titrated as needed for analgesia. In addition, the intravenous group received meperidine, 10 mg per dose, as required, from a patient-controlled analgesia pump. No other opioid was administered during the study period. Patients were studied for recovery of spirometric tests of pulmonary function, visual analog pain scores, sedation, arterial blood gases, meperidine dose requirements, radiographic pulmonary complications, and neurologic signs and symptoms. A subgroup of 10 patients (5 from each group) had venous blood samples drawn every 24 hours for 96 hours and assayed for serum meperidine and normeperidine concentrations. Epidural meperidine analgesia was associated with improved postthoracotomy pulmonary function, better analgesia scores, and lower meperidine dose requirements than intravenous PCA meperidine. There were no differences between the epidural versus intravenous PCA subgroups with respect to serum meperidine or normeperidine levels. Normeperidine levels greater than 300 ng/mL were associated with an increased incidence of shakiness and/or tremors. Meperidine provides satisfactory postthoracotomy analgesia via a lumbar epidural infusion. This analgesia is associated with improved recovery of postoperative pulmonary function when compared with an intravenous PCA meperidine infusion.

Immunohistochemical localization of nitric oxide synthase and the oxidant peroxynitrite in lung transplant recipients with obliterative bronchiolitis

BACKGROUND

Obliterative bronchiolitis (OB) is a disease affecting a large percentage of lung and heart-lung transplant recipients. Histologically, the disease is characterized by inflammation, cellular proliferation, and obliteration of terminal airways.

METHODS

We investigated the production of inducible and constitutive nitric oxide synthases and peroxynitrite by immunohistochemistry in the lungs of control subjects (n=14) compared with those of transplant recipients with OB (n=8).

RESULTS

Strong immunoreactivity for inducible nitric oxide synthase and nitrotyrosine, a marker of protein nitration by peroxynitrite, was seen in inflammatory cells, airway epithelium, and vascular endothelium of patients with OB, compared with little immunoreactivity in control lungs. Immunoreactivity for constitutive nitric oxide synthase was abundant in the airway epithelium and vascular endothelium of control lungs, however, it was decreased in airway epithelial cells and arterial endothelial cells of patients with OB.

CONCLUSIONS

We conclude that increased formation of the potent oxidant peroxynitrite and decreased production of endothelial nitric oxide may contribute to the functional and morphological abnormalities of OB.

A survey on minimally invasive coronary artery bypass grafting

BACKGROUND

There is increasing interest in performing minimally invasive coronary artery bypass grafting. To evaluate the current level of acceptance and utility of this procedure a survey of 162 cardiothoracic surgeons was conducted.

RESULTS

Currently only 16% of surveyed surgeons performed more than 10 minimally invasive coronary artery bypass grafting procedures. Most were less than 55 years old and in private practice. The majority predicted that it will be indicated in less than 25% of coronary artery bypass grafting cases and considered minimally invasive coronary artery bypass grafting a modification of existing techniques rather than investigational. Most believed exposure and stabilization of the coronary arteries on the beating heart to be the most challenging part and expressed concern with quality of the anastomosis.

CONCLUSIONS

We conclude that minimally invasive coronary artery bypass grafting is rapidly gaining acceptance in younger surgeons as techniques are improved. Despite concerns with adequacy of anastomosis the procedure is not considered investigational and follow-up is not rigorous.

Early cellular events in the lung allograft

We hypothesized that ischemic insult to the lung allograft may render it more susceptible to rejection. Left canine single-lung allografts were subjected to usual periods of cold and warm ischemia (4 hours and 1 hour, respectively). Bronchoalveolar lavage and open lung biopsies were performed at 0, 1, 4, and 24 hours and 1 week after transplantation. Bronchoalveolar lavage fluid was examined for cellular phenotypes, lymphocyte lectin-mediated cytotoxicity, and natural killer cell cytotoxicity. Open lung biopsy specimens were examined for severity of injury/rejection and MHC class II expression. Within 1 to 4 hours of reimplantation, we observed marked influx of polymorphonuclear leukocytes and lymphocytes and an increase in lectin-mediated cytotoxicity (25.6% +/- 14.8% and 50.6% +/- 20.1% versus 5.4% +/- 7.5% preoperatively; p < 0.05). In addition, natural killer cell cytotoxicity increased from 10.2% +/- 13.5% before transplantation to 20.5% +/- 8.6% 4 hours after transplantation (p < 0.03). By 24 hours MHC class II expression became evident and continued to increase while subtle histologic evidence of rejection appeared by 1 week. We conclude that ischemia-reperfusion injury can alter the local bronchopulmonary milieu, thus rendering it more susceptible to the development of rejection.

Efficacy of administering an endothelin-receptor antagonist (SB209670) in ameliorating ischemia-reperfusion injury in lung allografts

The purpose of this study was to determine whether treatment with an endothelin-1 (ET-1)-receptor antagonist could prevent ET-1-mediated ischemia-reperfusion injury and early allograft dysfunction. Eleven dogs were subjected to left lung allotransplantation. Donor lungs were preserved with modified Eurocollins solution and stored at 4 degrees C for 18 to 20 h. Animals received an intravenous infusion of either the ET-receptor antagonist SB209670 (n = 6) (15 microg/kg/min) or saline (control, n = 5), in a blinded fashion. The infusion started 30 min before transplantation and continued for up to 6 h after transplantation. Hemodynamic measurements, blood gas tensions, and plasma samples were obtained with animals functioning solely on the transplanted lung. Open-lung biopsies were obtained for wet-to-dry-weight ratios and histologic and immunohistochemical analyses. Survival at 6 h after transplantation was 40% in the control group and 100% in the treatment group. Pulmonary vascular resistance and lung tissue wet-to-dry-weight ratio were significantly lower in treated animals at 3 and 6 h after transplantation. Histology of the transplanted lungs revealed more intense airway and interstitial inflammatory infiltration and edema in the control group. Arterial and venous plasma ET-1 concentrations increased after transplantation; however, they were significantly higher in the treatment group. Immunohistochemical analysis revealed more intense ET-1 immunostaining in the airways and parenchyma of the treatment group. We conclude that treatment of lung allografts with the mixed endothelin A/endothelin B (ETA/ETB) receptor antagonist SB209670 can ameliorate ischemia-reperfusion injury, resulting in improved graft function and survival after lung transplantation.

Intraoperative localization techniques for pulmonary nodules

Video-assisted thoracoscopic resection has emerged as a safe procedure for diagnosis and treatment of peripheral pulmonary nodules. Its role alone or with adjuvant radiotherapy in the management of high-risk patients with T1 peripheral lung cancer is currently under evaluation. Most often, inspection of the lung with imaging will reveal surface changes indicative of tumor location (erythema, puckering, scarring), and gentle instrumental probing will allow both visual and tactile discrimination of normal and tumor boundaries. With experience, most lesions can be identified this way. However, when experience is limited, in particular circumstances where lesions are very small, located posteromedially or basomedially, or when there is underlying lung disease (eg, lung fibrosis, radiation changes, adhesions), intraoperative identification of peripheral nodules can be difficult. Computed tomography of the chest helps in planning the operative procedure, the position of the patient, and the ideal ports. Methylene blue injection and insertion of a guidewire into the lung nodule facilitates its identification intraoperatively. We found ultrasound probes to be helpful in defining the tumor's margins and its relation to bronchovascular structures, and thus in planning the strategy of resection whether by stapling devices, cautery, or laser dissection.

Cytokine interleukin-2, tumor necrosis factor-alpha, and interferon-gamma release after ischemia/reperfusion injury in a novel lung autograft animal model

Previously, we have reported an increase in the cytokines interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) early after left lung allotransplantation in dogs. The purpose of this study was to develop a novel model of canine lung autotransplantation and to observe whether ischemia/reperfusion injury alone (in the absence of an allogenic stimulus) would result in this cytokine release as seen in the allograft. Thus, using this model, early changes in cellular and cytokine composition in the lung autograft were monitored through the use of bronchoalveolar lavage (BAL) and plasma. The effects of ischemia/reperfusion injury on lung histology and major histocompatibility class II (MHC II) antigen expression were also observed. Ten mongrel dogs were subjected to left lung autotransplantation. Lungs were stored cold for 4 h, with a warm ischemic time of 1 h. BAL, blood, and biopsy specimens were taken preoperatively and 1 h, 4 h, 24 h, and 1 wk postoperatively. The mean BAL IL-2 levels significantly rose from a preoperative value of 150 +/- 19 pg/ml to 246 +/- 67 pg/ml 4 h after transplantation (p < 0.05), decreasing to preoperative levels after 24 h (128 +/- 54 pg/ml). Plasma levels of IL-2 did not change from preoperative values. In contrast to IL-2, TNF-alpha and IFN-gamma did not change in either BAL or plasma of the autograft.(ABSTRACT TRUNCATED AT 250 WORDS)

A novel charcoal-induced model of obliterative bronchiolitis-like lesions: implications of chronic nonspecific airway inflammation in the development of posttransplantation obliterative bronchiolitis

OBJECTIVES

In this study, we describe the development of a nonallogeneic animal model of obliterative bronchiolitis-like lesions. Furthermore, we examined whether chronic rejection alone can lead to the development of obliterative bronchiolitis or whether additional nonspecific airway inflammation is required.

METHODS

Part I: Rats were intratracheally injected with 0.2 ml of activated charcoal or sorbitol solution (carrier for charcoal control). Animals were put to death beginning at 2 weeks up to 20 weeks. Part II: Animals were divided into three groups: group I, underimmunosuppressed Brown Norway to Lewis lung allografts; group II, charcoal-treated underimmunosuppressed allografts; and group III, charcoal-treated rats. Animals were put to death at 3 months after transplantation.

RESULTS

Part I: In charcoal-laden bronchioles, subacute nonspecific airway inflammation was detected at 2 weeks. Slow, subclinical fibroproliferation ensued during the following weeks. Obliterative bronchiolitis-like lesions were observed in 80% of charcoal-treated animals at 12 weeks. Part II: Allografts developed extensive vascular lesions consistent with acute and chronic vascular rejection. Obliterative bronchiolitis-like lesions were scarcely detected. Charcoal-treated allografts demonstrated evidence of diffuse and severe obliterative bronchiolitis-like lesions.

CONCLUSIONS

Transtracheal injection of activated charcoal into native lungs results in slowly progressive airway injury and inflammation leading to obliterative airway lesions. Inadequate immunosuppression primarily results in chronic vascular rejection but not obliterative bronchiolitis. Underimmunosuppressed allografts subjected to nonspecific airway inflammation develop obliterative airway lesions that are more prominent than in native lungs. This suggests that a cofactor to chronic rejection is likely necessary for the development of lung transplant obliterative bronchiolitis.

Alterations in bronchoalveolar lavage and plasma endothelin-1 levels early after lung transplantation

A temporary increase in pulmonary vascular resistance is observed during the first 24 hr following lung allotransplantation. We hypothesized that such early vascular changes are secondary to endothelial injury by ischemia-reperfusion, and that this may be mediated by an increased pulmonary endothelin-1 production/release. To test this hypothesis, radioimmunoassay was used to analyze endothelin-1 levels in bronchoalveolar lavage and plasma taken before surgery and at 1 hr, 4 hr, 24 hr, and 1 week after transplantation. The study was carried out on 2 groups of mongrel dogs. One group was subjected to left single-lung allotransplantation and the other to autotransplantation. Endothelin-1 levels in the bronchoalveolar lavage samples from the lung allografts were significantly increased at 1 (0.70 +/- 0.18 pg/ml) and 4 (1.84 +/- 0.65 pg/ml) hr after transplantation compared with the preoperative value (0.14 +/- 0.05 pg/ml), and declined at 24 (0.85 +/- 0.84 pg/ml) hr after transplantation. Similarly, plasma endothelin-1 levels in the allografts were significantly increased at 1 (2.0 +/- 0.80 pg/ml) and 4 (2.0 +/- 0.71 pg/ml) hr after transplant when compared with preoperative levels (0.54 +/- 0.09 pg/ml). Plasma endothelin-1 levels, however, remained significantly high after 24 hr (1.4 +/- 0.4 pg/ml; P < 0.007) and decreased after 1 week after transplant (0.89 +/- 0.32 pg/ml). On the other hand, endothelin-1 levels in bronchoalveolar lavage from the autograft group remained relatively unchanged; however, plasma levels showed a significant increase at 4 hr (6.6 +/- 1.8 pg/ml) after transplantation compared with preoperative levels (2.8 +/- 0.38 pg/ml). Elevation of endothelin-1 levels early after lung transplantation may play an important role in early high pulmonary vascular resistance and temporary graft dysfunction.