Milton M. Sholley

Pretreatment with inhaled nitric oxide inhibits neutrophil migration and oxidative activity resulting in attenuated sepsis-induced acute lung injury

OBJECTIVE To determine if, and by what mechanisms, inhaled nitric oxide attenuates acute lung injury in a porcine model of adult respiratory distress syndrome induced by Gram-negative sepsis. DESIGN Nonrandomized, controlled study. SETTING Laboratory at a university medical center. SUBJECTS Thirty pathogen-free Yorkshire swine (15 to 20 kg). INTERVENTIONS Four groups of swine were anesthetized, mechanically ventilated, and studied for 5 hrs. Both control-nitric oxide and septic-nitric oxide animals received inhaled nitric oxide at 20 parts per million throughout the study. Control (n = 10) and control-nitric oxide (n = 5) animals received a 1-hr infusion of sterile saline. Sepsis was induced in septic (n = 10) and septic-nitric oxide (n = 5) animals with a 1-hr intravenous infusion of live Pseudomonas aeruginosa. MEASUREMENTS AND MAIN RESULTS Untreated septic animals developed a progressive decrease in Pao2 that was prevented in septic-nitric oxide animals (73 +/- 4 vs. 214 +/- 23 torr [9.7 +/- 0.5 vs. 28.5 +/- 3.1 kPa], respectively, at 5 hrs, p < .05). Untreated septic animals showed a significant increase in bronchoalveolar lavage protein and neutrophil count at 5 hrs, compared with the baseline value, indicating acute lung injury. Septic-nitric oxide animals showed no significant increase in these parameters. Peripheral blood neutrophils from untreated septic animals and septic-nitric oxide animals exhibited significant (p < .05) up-regulation of CD18 receptor expression and oxidant activity (10.5 +/- 0.9 and 5.0 +/- 0.9 nmol of superoxide anion/10(6) neutrophils/10 mins, respectively) compared with both control and control-nitric oxide animals (3.0 +/- 0.6 and 2.6 +/- 0.2 nmol of superoxide anion/10(6) neutrophils/10 mins, respectively). Also, priming for the oxidant burst at 5 hrs was decreased by 50% in septic-nitric oxide animals compared with untreated septic animals. Both untreated septic and septic-nitric oxide animals showed a significant increase in pulmonary arterial pressure at 30 mins (47.5 +/- 2.4 and 51.0 +/- 3.0 mm Hg, respectively), followed by a progressive decrease (32.8 +/- 2.6 and 31.3 +/- 5.4 mm Hg, respectively, at 5 hrs). Both of these changes were significant (p < .05) compared with baseline values and compared with the control groups. There was no significant difference in pulmonary arterial pressure or systemic arterial pressure at any time between untreated septic and septic-nitric oxide animals. CONCLUSIONS These results demonstrate that inhaled nitric oxide attenuates alveolar-capillary membrane injury in this porcine model of Gram-negative sepsis but does not adversely affect systemic hemodynamics. The data suggest that inhaled nitric oxide preserves alveolar-capillary membrane integrity by the following means: a) inhibiting transendothelial migration of activated, tightly adherent neutrophils; and b) possibly by attenuating the neutrophil oxidant burst.

Ultrastructural Radiation Injury of Rat Parotid Gland: A Histopathologic Dose-Response Study

Radiation damage to rat parotid acinar cells was evaluated by electron microscopy using exposures of 400, 800, 1600, and 6400 R. Evidence of intracellular damage was observed at all exposures by the presence of focal cytoplasmic lesions involving all of the organelles. The extent of the damage varied with dose, 400 R resulted in very mild injury while 6400 R caused extensive necrosis (1-4 days after irradiation) with signs of recovery in evidence by Day 6. In addition, at the lower doses, 400 and 800 R, the Golgi complex was found to be hypertrophied although at the higher doses, 1600 and 6400 R, this did not occur. Therefore, it was determined that x-irradiation results in histopathologic changes to the parotid gland at a relatively low dose and the extent of the damage varies directly with dose.

Cold-water treatment of scald injury and inhibition of histamine-mediated burn edema

Using the hairless mouse ear burn model we have studied the effects of immediate short-term cold-water treatment (CWT) of a moderate scald injury (54°C water for 20 sec) to intact skin using 8–10°C water for 5 min. CWT following scald injury caused brief periods of arteriolar vasomotion and shortened the duration of postburn venular dilation by about 50% as compared to untreated burns. CWT significantly (P < 0.05) reduced edema formation of the burned ear for only the first 2 hr after injury as compared to untreated burns. Significant delayed remote edema formation normally observed in abdominal and unburned (contralateral) ear skin after untreated ear scald injury was abolished after CWT to the burned ear. Chemical inhibition of remote burn edema, comparable to that achieved with CWT, was produced by cimetidine pretreatment or histamine depletion prior to injury. CWT also significantly decreased tissue histamine loss of the burned ear after scald injury Ultrastructural demonstration of increased vacuole formations in capillary and venular endothelial cells in edematous, unburned ear skin 2 hr after untreated scald injury suggested the presence of histamine-mediated remote burn edema formation. Predominant pathophysiologic mechanisms of CWT in local and remote burn edema inhibition and perhaps burn shock protection were suggested as: (1) decreased vascular response with a shortened duration of postburn venular dilation, and, most importantly, (2) the inhibition of local and systemic histamine release from thermally injured tissues.

Macrophage heterogeneity in tumor resistance: Cytostatic and cytotoxic activity of corynebacterium parvum-activated and proteose peptone-elicited rat macrophages against Moloney sarcoma tumor cells☆

Peritoneal macrophages from proteose peptone and Corynebacterium parvum (CP)-treated Lewis and Brown Norway rats were separated into subpopulations by centrifugation on discontinuous gradients of Ficoll. Four macrophage subpopulations were prepared and tested for cytostatic and cytotoxic activity against syngeneic and allogeneic Moloney sarcoma tumor cells. Macrophages were cocultured with tumor cells for 48 hr, whereupon either the inhibition of [125I]iododeoxyuridine uptake was measured (cytostasis) or the tumor monolayers were observed for cytotoxic effects. CP-Activated macrophages from heavy-density portions of the gradient (8–10% and 10%-pellet) were highly cytostatic and cytotoxic to both the syngeneic and allogeneic tumor cells while macrophages from the light-density portions (4–6 and 6–8% Ficoll bands) were not. Proteose peptone-stimulated macrophages from the heavy-density portions of the gradient were cytostatic but not cytotoxic to the tumor cells. The effector macrophages from the CP-activated pool were large, well-differentiated cells as determined by electron microscopic examinations and had enhanced phagocytic activity when contrasted with the noncytotoxic, less dense macrophages.

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.