Daniel E. Bechard

Assessment of exercise oxygen consumption as preoperative criterion for lung resection

Determination of preoperative pulmonary function is crucial in avoiding complications from pulmonary resection. Many have employed static pulmonary function testing in an attempt to decrease morbidity and mortality from lung resections. The purpose of the present study was to correlate preoperative static pulmonary function, one-second forced expiratory volume (FEV1), and exercise O2 consumption (MVO2) with postoperative morbidity and mortality. Fifty consecutive patients underwent preoperative FEV1 and MVO2 determinations. A criterion for surgical resection included an FEV1 greater than 1.7 liters for pneumonectomy, greater than 1.2 liters for lobectomy, and greater than 0.9 liters for wedge resection. The surgeon was blinded as to the results of MVO2 studies. Mean age was 63.8 years (range, 47 to 76 years). There were 10 pneumonectomies, 28 lobectomies, and 12 wedge resections. Among the 50 surgical candidates selected solely on the standard FEV1 values, mortality was 4% (2/50) and morbidity, 12% (6/50). Stratification on the basis of exercise performance showed a 29% mortality (2/7) and a 43% morbidity (3/7) in patients with an MVO2 less than 10 ml/kg/min. Patients with an MVO2 less than 20 but greater than 10 ml/kg/min had a 10.7% morbidity (3/28), and there were no deaths. No patients with an MVO2 greater than 20 ml/kg/min sustained any morbidity or died (p less than 0.001). We conclude that exercise is an important criterion in the preoperative evaluation of patients for pulmonary surgery. An MVO2 less than 10 ml/kg/min is associated with significant morbidity and mortality.

CD18 adhesion receptors, tumor necrosis factor, and neutropenia during septic lung injury☆

Sequestration of neutrophils (PMNs) in the pulmonary microvasculature and associated neutropenia are characteristic features of experimental models of septic lung injury. The etiology of altered PMN kinetics during septic lung injury is uncertain, but may be partially due to increased adhesiveness of activated PMNs to pulmonary endothelium. This study examines the relationship between the expression of PMN CD18 adhesion receptors, the evolving neutropenia, and plasma tumor necrosis factor (TNF) activity in a porcine model of septic lung injury. Acute lung injury was induced by infusion of live Pseudomonas aeruginosa (5 x 10(8) CFU/ml at 0.3 ml/20 kg/min) for 60 min (Group Ps, n = 6). Control animals (Group C, n = 3) received a 60-min infusion of sterile 0.9% saline. CD18 expression of circulating PMNs was measured by quantitative immunofluorescent flow cytometry. Plasma TNF activity was measured by L929 fibroblast cytolytic assay. Group Ps developed a significant neutropenia by 30 min (14.9 +/- 2.5 vs 23.4 +/- 3.3 x 10(3) cells/microliter at baseline, P less than 0.05, ANOVA) with circulating neutrophils exhibiting significantly increased CD18 expression by 60 min (6.34 +/- 0.72 vs 5.01 +/- 0.52 equivalent soluble fluorescence molecules (ESFM) x 10(3) at baseline, P less than 0.05, ANOVA). Group Ps demonstrated a significant increase in plasma TNF activity by 30 min (2.5 +/- 0.9 vs 0.7 +/- 0.3 U/ml at baseline). There was no significant change in PMN count, PMN CD18 expression, or plasma TNF activity in Group C. In complimentary in vitro studies, porcine PMNs stimulated with recombinant human TNF-alpha (n = 5) demonstrated a time- and dose-dependent increase in CD18 expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonspecific Cytotoxicity of Recombinant Interleukin-2 Activated Lymphocytes

The administration of interleukin-2 (IL-2) and lymphokine activated killer (LAK) cells to patients with advanced metastatic cancer has yielded encouraging results. The purported ability of LAK cells to be discriminatively tumoricidal, thus sparing normal host tissue, represents a major advance over conventional chemotherapy. However, IL-2 adoptive immunotherapy results in dose-limiting toxicity characterized by weight gain, dyspnea, ascites, and peripheral-pulmonary edema suggestive of a vascular leak syndrome. It is unclear whether the observed toxicity is directly related to IL-2 and/or LAK cells. The authors examined the cytolytic nature of human LAK cells against human endothelial, epithelial, and fibroblast cell lines. Bovine endothelial cells also were studied. Using a 51Cr release assay, the cytolytic potential, time course, and effect of reactive oxygen intermediate inhibitors were studied. LAK cells were uniformly toxic against all cell lines, in contrast to high dose rIL-2 and excipient. Significant cytolysis was observed within 30 minutes and increased over the first 2 hours of LAK cells coming in contact with target cells. Reactive oxygen intermediate inhibitors did not reduce cytolytic activity. The authors thus found human LAK cells to be rapidly cytolytic against a variety of human and bovine cell lines. This cytolysis was independent of reactive oxygen intermediates.

In situ pulmonary vascular perfusion for improved recovery of pulmonary intravascular macrophages

The microcirculation contains mononuclear phagocytes, with features characteristic of macrophages, adhered to luminal capillary surfaces by intercellular adhesion plaques. These pulmonary intravascular macrophages may play an important role in regulating lung vascular tone and capillary permeability, and may modulate capillary endothelial cell growth and replication by the secretion of soluble mediators (i.e., arachidonate metabolites, cytokines). This study describes a technique which utilizes in situ lung perfusion to remove intravascular macrophages in large numbers from the microcirculation of porcine lung (n = 26). This technique yielded 3.8 +/- 0.5 x 10(8) (mean +/- SEM) mononuclear cells which were highly phagocytic toward particulate carbon (phagocytic index, 80 +/- 6%). Harvested mononuclear phagocytes reestablished intercellular adhesion plaques when placed on small vessel porcine pulmonary artery endothelial cell monolayers and exhibited histochemical characteristics typical of monocyte/macrophage lineage cells. Mononuclear cells obtained from lung microcirculation displayed size heterogeneity varying from 10.4 to 16.5 microns in diameter. Both large and small cell populations phagocytosed particulate carbon. Morphometric studies performed on collagenase-treated lung demonstrated that in situ perfusion removed significant numbers of intravascular macrophages in lung capillaries. The technique described permits the rapid removal of anchored mononuclear phagocytes from lung capillaries with minimal postmortem delay.

In vivo interleukin-2 activated sheep lung lymph lymphocytes increase ovine vascular endothelial permeability by non-lytic mechanisms

Therapeutic doses of recombinant interleukin-2 (rIL-2) often result in systemic toxicity consistent with increased vascular permeability. rIL-2 activated lymphocytes (IALs) may produce endothelial dysfunction and have cytolytic potential. However, much of the data on IAL cytotoxicity comes from the use of in vitro activated IALs. Alternatively, rIL-2 may enhance permeability directly or via release of various cytokines by host effector cells. The cytotoxicity of in vivo activated lung lymph lymphocytes has been studied in an ovine model of rIL-2 toxicity. The in vivo IALs had no significant endothelial cytolysis at effector to target ratios of 100:1. However, the in vivo IALs increased endothelial monolayer permeability to albumin, dependent on the concentration of IALs. rIL-2 induced no endothelial cytolysis or permeability alterations at doses of 10(5) and 2 x 10(5) U/ml, respectively. These findings suggest that the acute endothelial dysfunction characteristic of the vascular leak syndrome is not due to rIL-2 directly, but is mediated by in vivo IALs via non-cytolytic mechanisms and/or the release of secondary cytokines in response to rIL-2.

Responsiveness of guinea pig alveolar cells

Guinea pig alveolar cells were obtainedin situ via bronchoalveolar lavage. The cells were 86% macrophages (GPAM), (>97% viability) with the remainder of the population comprised of lymphocytes and eosinophils. The following battery of functional assays were studied in GPAM: chemotaxis was stimulated by N-formyl-methionyl-leucine-phenylalanine (FMLP) and by phorbol-12-myristate-13-acetate (PMA) in a concentration-related manner; cytotoxicity as measured by51Cr release from target cells ± PMA was induced in P815 mastocytoma cells and less strongly in 3T3 normal mouse fibroblasts; release of N-acetyl-β-D-glucosaminidase (NAGA) was stimulated by the calcium ionophore A23187, but not by PMA or the combination of PMA + A23187; superoxide anion production as measured by the reduction of ferricytochrome C was stimulated 25-fold by PMA; phagocytosis of opsonized51Cr sheep red blood cells occurred in a time-related manner and reached its maximum after 120 min; and cell spreading, which exhibited a high rate of spontaneous spreading (76%), was only minimally stimulatable by PMA. The responsiveness of the GPAM, the ease of retrieval, and the large numbers of cells available make the guinea pig an ideal system for future study.