High-dose nitric oxide inhalation increases lung injury after gastric aspiration

BACKGROUND

Inhaled nitric oxide is often used in patients with adult respiratory distress syndrome. However, nitric oxide also may be significantly toxic, especially if administered concurrently with hyperoxia. The authors evaluated the isolated effect of nitric oxide and the combined effects of nitric oxide and hyperoxia on lung injury in rats after acid aspiration.

METHODS

Animals were injured by instillation of 1.2 ml/kg hydrogen chloride in low-pH saline (the acid group) or acidified gastric particles (the casp group) into the lungs under halothane anesthesia via a tracheal catheter. Controls received no injury vehicle but rather underwent the surgical process. After recovery from anesthesia, the animals were exposed to 20% or 90% oxygen with or without 20, 40, or 80 ppm nitric oxide for 5 h. The permeability index, alveolar-arterial oxygen difference, the ratio of oxygen pressure to the inspired fraction of oxygen, and the ratio of wet to dry weight were assessed 5 h after injury as indices of lung injury. Data were assessed using analysis of variance.

RESULTS

Each group included 6-10 rats. Exposure to nitric oxide (80 ppm) in air increased protein permeability in the lungs to a permeability index of 1.42+/-0.12 after acid aspiration. The combination of nitric oxide (80 ppm) and hyperoxia further increased protein leakage to a permeability index of 2.1+/-0.25. Exposure to lower concentrations of nitric oxide (e.g., 20 and 40 ppm) increased the permeability index of the lungs (1.44+/-0.21, 1.75+/-0.29, respectively) in the presence of hyperoxia, although it did not affect the permeability index of the lungs during exposure to air. Pretreatment of animals with deferoxamine and methylene blue partially inhibited the adverse effect of hyperoxia and nitric oxide, which suggested a complex underlying mechanism involving both reactive-species generation and pulmonary vasomotor changes.

CONCLUSIONS

These results show that inhaled nitric oxide at 80 ppm for a short duration (5 h) increases the severity of the inflammatory microvascular lung injury after acid aspiration. The pulmonary damage is exacerbated further in the presence of high oxygen concentrations. Although lower concentrations of nitric oxide did not increase the extent of lung injury, longer exposure times need to be assessed.

The role of tumor necrosis factor-alpha in the pathogenesis of aspiration pneumonitis in rats

BACKGROUND

Aspiration pneumonitis is characterized by proteinaceous pulmonary edema and acute infiltration of neutrophils into the alveolar space. This study examined the role of the proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), on the pathogenesis of the injury produced by the different components that may be present in the aspirate, acid, or gastric particles.

METHODS

Rats were injured by intratracheal instillation of a vehicle containing acid or gastric particles. TNF-alpha concentration of bronchoalveolar lavage fluid was determined using a bioassay. upregulation of lung TNF-alpha mRNA was also measured. The effect of intratracheal anti-rat TNF-alpha treatment was assessed by lung protein permeability, blood gases, and lung myeloperoxidase activity.

RESULTS

Injury vehicle alone and acid injury resulted in a small TNF-alpha peak 1-2 h after injury in the lavage fluid. Both particulate and acidic particulate groups produced a much more robust TNF-alpha signal that reached a plateau at 2-4 h after injury and declined at 8 h. Upregulation of TNF-alpha mRNA was only detected in the particulate-containing groups. Acidic particulate exposure yielded a synergistic increase in protein permeability and decrease in blood oxygenation. Anti-TNF-alpha treatment reduced protein permeability and myeloperoxidase activity and increased blood oxygenation in the groups exposed to only acid. Such treatment had no effect on either of the particulate containing injuries.

CONCLUSIONS

TNF-alpha is differentially manifested according to the components that make up the aspirate but the levels of TNF-alpha expression do not correlate with the severity of the resultant injury. However, the reduction in acid-induced lung injury by anti-TNF-alpha treatment indicates that TNF-alpha plays a role in the pathogenesis of aspiration pneumonitis.

Characteristics of nonmalignant and malignant human prostate in organ culture

Prostate tissue was obtained from 52 radical prostatectomies immediately upon surgery. From each specimen, a small piece of tissue was fixed in 10% buffered formalin and used for histology, cytokeratin staining, staining with the antibodies to the proliferation-associated antigen (Ki-67), and histochemical evaluation of the epithelial-stromal basement membrane. A second piece was used for the isolation of epithelial cells and stromal cells in monolayer culture. The remainder of each specimen was cut into cubes (approximately 1 mm on a side) and incubated in organ culture for up to 20 days. At the end of the incubation period, tissue was fixed in 10% buffered formalin and examined as described above with zero-time tissue. These studies showed that normal epithelial and stromal elements survived in organ culture in the presence of a serum-free medium containing a mixture of growth factors (epidermal growth factor, insulin, pituitary extract, and dihydrotestosterone). In many of the tissues examined at 4 days, individual glands resembled those seen immediately after surgery, with a single layer of basal epithelial cells and a layer of secretory cells above. By Day 8, the secretory epithelium was lost in many places and basal cells proliferated to fill in the lumens of the glands. All of the nonmalignant glands were reactive with the anti-cytokeratin antibody (K903), and there was a large increase in the number of cells staining for Ki-67 as compared with zero-time tissue. Staining with the Periodic Acid Schiff (PAS) and PAS-methenamine silver (PASME) reagents revealed an intact basement membrane around virtually all of the epithelial structures. The basement membrane appeared to be thickened in some areas. In places where a gland was cut during the processing of the tissue, epithelial cells migrated out of the gland and covered the cut surface of the tissue piece. There was no detectable basement membrane separating the epithelium from the stroma at these sites. Whereas nonmalignant epithelial cells were preserved in the growth factor- and dihydrotestosterone-supplemented culture medium, most of the malignant cells rapidly lysed under the same conditions. However, when phorbol myristate acetate was included in the culture medium, many of the tumor cells remained viable. This was seen with the more well-differentiated tumors as well as with tumors that were highly anaplastic. All of the tumor cells were nonreactive with anti-cytokeratin antibody, and only a few cells stained for Ki-67. The basement membrane surrounding malignant cells was thin and, in places, appeared to be discontinuous. Where malignant glands were cut in the processing of the tissue, cells did not migrate out over the cut surface. In summary, this study identifies culture conditions for the successful maintenance of human prostate tissue for several days in organ culture. Histological/histochemical features that distinguish nonmalignant and malignant tissue are present in this model.

Role of matrix metalloproteinases in models of macrophage-dependent acute lung injury. Evidence for alveolar macrophage as source of proteinases

Matrix metalloproteinases (MMPs) have been implicated in the tissue injury seen in neutrophil-dependent models of acute lung injury. However, the role of MMPs in macrophage-dependent models of lung injury is unknown. To address this issue, the macrophage-dependent immunoglobulin A immune complex-induced lung injury model and the macrophage-dependent portion of the lipopolysaccharide-induced acute lung injury model in the rat were assessed for MMP involvement and for the source of these activities. In both models, injury was inhibited by the recombinant human tissue inhibitor of metalloproteinases-2. Bronchoalveolar lavage fluids (BALFs) from injured animals in both models showed increased levels of MMPs. Characterization of MMP production by isolated lung fibroblasts, endothelial cells, type II epithelial cells, and alveolar macrophages revealed that only the macrophage had the same spectrum of MMP activity as seen in the BALF. Further, isolated alveolar macrophages from injured lungs showed evidence of in vivo activation with the release of the same spectrum of MMP activities. Together these studies show that MMPs are produced during macrophage-dependent lung injury, that these MMPs play a role in the development of the lung injury, and that the alveolar macrophage is the likely source of these MMPs.

Characterization of matrix metalloproteinases produced by rat alveolar macrophages

Evidence presented in the accompanying article (Gibbs, D. F., T. P. Shanley, R. L. Warner, H. S. Murphy, J. Varani, and K. J. Johnson. 1999. Role of matrix metalloproteinases in models of macrophage-dependent acute lung injury: evidence for alveolar macrophage as source of proteinases. Am. J. Respir. Cell Mol. Biol. 20:1145-1154) implicates alveolar macrophage matrix metalloproteinases (MMPs) in two models of acute lung inflammation in the rat. As a prerequisite to understanding which specific MMPs might be involved in the injury and how they might function, it was necessary to know the spectrum of enzymes present. To this end, alveolar macrophages were obtained from normal rat lungs by bronchoalveolar lavage, placed in culture with and without various agonists, and assessed by a variety of techniques for MMPs. The identification process involved characterization by gelatin, beta-casein, and kappa-elastin zymography, with confirmation of identity by Western blot/immunoprecipitation. Message levels of detected MMPs were assessed by Northern blot. Rat alveolar macrophages were found to produce a low constitutive level of MMP-2 (72-kD gelatinase A) that was only modestly upregulated following stimulation with phorbol myristate acetate, bacterial lipopolysaccharide, or immunoglobulin A-containing immune complexes. Although control cells were found to produce little or no MMP-9 (92-kD gelatinase B) or MMP-12 (metalloelastase), both enzymes were markedly upregulated upon stimulation. In the same stimulated macrophages there was little activity against type I collagen (associated with MMP-13 [collagenase-3] on the basis of Western blotting), no activity suggestive of stromelysin or matrilysin, and no measurable secretion of the serine proteinases, elastase and cathepsin G. These data demonstrate the ability of rat alveolar macrophages to elaborate certain MMPs under proinflammatory conditions, consistent with their possible involvement in the progression of acute inflammation.

The compact conformation of fibronectin is determined by intramolecular ionic interactions

Fibronectin exists in a compact or extended conformation, depending upon environmental pH and salt concentration. Using recombinant fragments expressed in bacteria and baculovirus, we determined the domains responsible for producing fibronectin's compact conformation. Our velocity and equilibrium sedimentation data show that FN2-14 (a protein containing FN-III domains 2 through 14) forms dimers in low salt. Experiments with smaller fragments indicates that the compact conformation is produced by binding of FN12-14 of one subunit to FN2-3 of the other subunit in the dimer. The binding is weakened at higher salt concentrations, implying an electrostatic interaction. Furthermore, segment FN7-14+A, which contains the alternatively spliced A domain between FN11 and 12, forms dimers, whereas FN7-14 without A does not. Segment FN12-14+A also forms dimers, but the isolated A domain does not. These data imply an association of domain A with FN12-14, and the presence of A may favor an open conformation by competing with FN2-3 for binding to FN12-14.

Cloning and chromosomal localization of human Cdc42-binding protein kinase beta

The p21 GTPases, Rho and Cdc42, regulate numerous cellular functions by binding to members of a serine/threonine protein kinase subfamily. These functions include the remodeling of the cell cytoskeleton that is a feature of cell growth and differentiation. Two of these p21 GTPase-regulated kinases, the myotonic dystrophy protein kinase-related Cdc42-binding kinases (MRCKalpha and beta), have been recently characterized in rat. Both of these proteins phosphorylate nonmuscle myosin light chain, a prerequisite for the activation of actin-myosin contractility. Here we report the cDNA cloning of the human homologue of MRCKbeta, CDC42BPB, which was found by Northern blot analysis to be expressed in a wide range of tissues. The human CDC42BPB gene maps to cytogenetic band 14q32.3 by FISH analysis.

Regulatory effects of endogenous protease inhibitors in acute lung inflammatory injury

Inflammatory lung injury is probably regulated by the balance between proteases and protease inhibitors together with oxidants and antioxidants, and proinflammatory and anti-inflammatory cytokines. Rat tissue inhibitor of metalloprotease-2 (TIMP-2) and secreted leukoprotease inhibitor (SLPI) were cloned, expressed, and shown to be up-regulated at the levels of mRNA and protein during lung inflammation in rats induced by deposition of IgG immune complexes. Using immunoaffinity techniques, endogenous TIMP-2 in the inflamed lung was shown to exist as a complex with 72- and 92-kDa metalloproteinases (MMP-2 and MMP-9). In inflamed lung both TIMP-2 and SLPI appeared to exist as enzyme inhibitor complexes. Lung expression of both TIMP-2 and SLPI appeared to involve endothelial and epithelial cells as well as macrophages. To assess how these endogenous inhibitors might affect the lung inflammatory response, animals were treated with polyclonal rabbit Abs to rat TIMP-2 or SLPI. This intervention resulted in significant intensification of lung injury (as revealed by extravascular leak of albumin) and substantially increased neutrophil accumulation, as determined by cell content in bronchoalveolar lavage (BAL) fluids. These events were correlated with increased levels of C5a-related chemotactic activity in BAL fluids, while BAL levels of TNF-alpha and chemokines were not affected by treatment with anti-TIMP-2 or anti-SLPI. The data suggest that endogenous TIMP-2 and SLPI dynamically regulate the intensity of lung inflammatory injury, doing so at least in part by affecting the generation of the inflammatory mediator, C5a.

Characterization of the expression of DMPK and SIX5 in the human eye and implications for pathogenesis in myotonic dystrophy

The pathogenic mechanisms underlying myotonic dystrophy (DM), which results from a (CTG) n repeat expansion mutation in the 3'-untranslated region (3'-UTR) of the myotonic dystrophy protein kinase gene ( DMPK ), remain obscure. The multisystemic nature and variable expressivity of the symptoms are unlikely to be explained by a defect in this gene alone. However, the location of the DM-associated (CTG) n repeat in the promoter region of SIX5, immediately downstream of DMPK, implicates it as a second candidate with a pathological role in DM. We hypothesize that dysfunction of SIX5, which is homologous to the Drosophila eye development gene sine oculis ( so ), is primarily responsible for the ophthalmic features of DM. We report an expression pattern for SIX5 in the normal adult eye that matches the sites of the ocular pathology in DM. SIX5 transcripts were detected in the adult corneal epithelium and endothelium, lens epithelium, ciliary body epithelia, cellular layers of the retina and the sclera. SIX5 expression was not detected in fetal eyes. We also report a restricted but partially overlapping expression pattern for DMPK transcripts and DMPK protein in normal fetal and adult eyes. DMPK transcripts were detected in fetal eyes and in adult conjunctival and corneal epithelia, uvea, cellular layers of the retina, optic nerve and in the sclera. DMPK protein was detected in the adult retina, conjunctival and ciliary body epithelia and in the smooth muscle of the ciliary body, pupillary sphincter and uveal blood vessels. We propose that the expression patterns of these two genes indicate their relative contribution to the ophthalmological dysfunction seen in DM. Furthermore, the expression of SIX5 and not DMPK in the adult lens implicates a role for SIX5 dysfunction in the development of adult onset cataracts, the most frequently occurring eye phenotype in DM.

The presence and significance of lymphadenopathy detected by CT in primary sclerosing cholangitis

Patients with primary sclerosing cholangitis (PSC) are at increased risk of developing cholangiocarcinoma, which adversely affects their survival especially after orthotopic liver transplantation. All CT scans of patients with PSC referred to the Liver Unit at the Queen Elizabeth Hospital since 1992 were reviewed. The location of any lymph node with a short axis diameter greater than normal was documented. The incidence of lymphadenopathy and cholangiocarcinoma was also documented. 36 scans are reviewed, including eight with cholangiocarcinoma as well as PSC. Abdominal lymphadenopathy was present in 26 cases (66%) and 45 separate lymph node groups were involved in these patients. There were eight cases of cholangiocarcinoma; five were detectable on CT, but only four had significant lymphadenopathy. The remaining three cases of cholangiocarcinoma were not detectable on CT and only one of these had lymphadenopathy. Follow-up of the remaining patients has not demonstrated the development of cholangiocarcinoma. Lymphadenopathy is commonly demonstrated by CT in PSC patients, but does not imply malignancy and should not exclude a patient from undergoing liver transplantation. Conversely cholangiocarcinoma may develop without significant lymphadenopathy.

Interactions of p62(dok) with p210(bcr-abl) and Bcr-Abl-associated proteins

A 62-kDa Ras GTPase-activating protein (RasGAP)-associated protein is tyrosine-phosphorylated under a variety of circumstances including growth factor stimulation and in cells transformed by activated tyrosine kinases. A cDNA for p62(dok), reported to be the RasGAP-associated 62-kDa protein, was recently cloned from Abl-transformed cells. In this study, the interactions of p62(dok) with Bcr-Abl and associated proteins were examined. In 32D myeloid cells and Rat-1 fibroblasts transformed by p210(bcr-abl), p62(dok) is tyrosine-phosphorylated and co-immunoprecipitates with Bcr-Abl, RasGAP, and CrkL, a Src homology 2 (SH2) and SH3 domain-containing adaptor protein. Tyrosine-phosphorylated p62(dok) from cells expressing p210(bcr-abl) bound directly to the SH2 domains of Abl and CrkL in a gel overlay assay. Previous work has shown that an SH2 domain deletion mutant of Bcr-Abl is defective in transforming fibroblasts but remains capable of inducing myeloid growth factor independence. In both fibroblasts and myeloid cells expressing this mutant, p62(dok) is underphosphorylated as compared with cells expressing full-length p210(bcr-abl) but remains capable of associating with Bcr-Abl. However, in a gel overlay assay, p62(dok) from cells expressing the SH2 domain deletion was incapable of associating directly with SH2 domains of Abl and CrkL. Interestingly, no direct binding between Bcr-Abl and p62(dok) could be demonstrated in a yeast two-hybrid assay. These data suggest that indirect interactions mediate the interaction between Bcr-Abl and p62(dok) and that the SH2 domain of Bcr-Abl is required for hyperphosphorylation of p62(dok). Further, hyperphosphorylation of p62(dok) correlates with the ability of Bcr-Abl to transform fibroblasts but not with the induction of growth factor independence in myeloid cells.

Quantitative morphometry of renal biopsies prior to cyclosporine in nephrotic syndrome

Use of cyclosporine (CsA) in the management of children with steroid-resistant (SRNS) and steroid-dependent (SDNS) nephrotic syndrome has become increasingly popular in recent years. Although most children receive a renal biopsy prior to initiation of CsA, the relationship between initial renal histology and the subsequent clinical response to CsA is not known. We analyzed the correlation between pre-CsA segmental and global glomerular scarring and interstitial fibrosis and the subsequent response to CsA in 23 children (5.6+/-1.0 years, Mean+/-SEM) with SDNS (n=8) and SRNS (n=15) treated with CsA for 24.2+/-3.8 months and followed for 28.0+/-4.1 months. Complete remission was obtained in 78% of patients within 67.6+/-16 days, while 18% had a partial response and 4% no response. Quantitative histological analysis revealed a trend toward partial rather than complete response with increasing segmental glomerular (P=0.13), global glomerular (P=0.05), and interstitial (P=0.08) scarring, and among patients with minimal change nephrotic syndrome versus IgM nephropathy versus focal segmental glomerulosclerosis. Among complete responders, linear regression analyses revealed no correlation between time to response and pre-CsA glomerular or interstitial scarring. We conclude that increased glomerular or interstitial scarring on a pre-CsA renal biopsy tends to correlate with a partial, rather than complete, response to CsA in childhood nephrotic syndrome.

Urinary bombesin-like peptide levels in infants and children with bronchopulmonary dysplasia and cystic fibrosis

Compared to normal infants and children, there are increased numbers of neuroendocrine cells with bombesin-like peptide (BLP) immunostaining in the lungs of infants and children with bronchopulmonary dysplasia (BPD) and cystic fibrosis (CF). However, there are no data documenting levels of urinary BLP in normal infants and children, or in children with lung disease. We therefore determined the normal developmental pattern for urinary BLP excretion in healthy infants and children, and in infants and children with BPD and CF, and correlated these findings with the subjects' clinical course. We measured urinary BLP levels in 110 subjects: 54 controls, 33 with BPD, and 23 with CF. An age-dependent decline in urinary bombesin levels was evident in the control and BPD subjects, but not in those with CF. There were no statistically significant differences in BLP levels between normal infants and those with BPD. Mean BLP levels were higher in the more immature preterm infants with BPD who required increased ventilatory support. The highest mean BLP levels were documented in BPD infants under age 3 months (882 fmol/mg creatinine), in controls between 3 and 12 months of age (625 fmol/mg creatinine), and in 12-60-month-old CF subjects (486 fmol/mg creatinine). Thus there is an age-dependent decline in BLP levels in controls and BPD, but not in CF. We speculate that the elevated urinary BLP levels in infants and children with BPD and CF may reflect increased pulmonary neuroendocrine cell activity in these conditions, due to the epithelial regenerative response to airway damage and repair.

Neutrophil accumulation is reduced during partial liquid ventilation

OBJECTIVE

This study evaluates the ability of perflubron to inhibit pulmonary neutrophil accumulation during partial liquid ventilation (PLV) in the setting of acute lung injury.

DESIGN

Randomized, controlled, nonblinded study.

SETTING

Research laboratory at a university.

SUBJECTS

Male, Sprague-Dawley rats (n = 120, 506 +/- 42 g).

INTERVENTIONS

Animals were divided into eight groups (n = 15 in each group, of which n = 12 for myeloperoxidase content and n = 3 for histologic neutrophil counting): a) GV-CVF group, animals received gas ventilation (GV) with the induction of lung injury using cobra venom factor (CVF); b) PLV-CVF group, animals received partial liquid ventilation before the induction of lung injury; c) PEEP-CVF group, animals received positive end-expiratory pressure (PEEP) before the administration of cobra venom factor; d) CVF-PLV group, animals received partial liquid ventilation after cobra venom factor; e) CVF-PEEP group, animals received PEEP after cobra venom factor; f) PLV only group, animals received partial liquid ventilation only; g) GV only group, animals received gas ventilation only; and h) NVSBA group, nonventilated spontaneous breathing animals.

MEASUREMENTS AND MAIN RESULTS

After the experimental period, total lung myeloperoxidase content was significantly decreased in the PLV-CVF (0.29 +/- 0.08, p = .02) and PEEP-CVF (0.34 +/- 0.04, p = .01) groups when compared with the GV-CVF group (0.62 +/- 0.07). When compared with the GV-CVF group, a trend toward a reduction in myeloperoxidase was observed in the CVF-PLV (0.42 +/- 0.05, p = .07) and the CVF-PEEP (0.39 +/- 0.06, p = .07) groups. When compared with the cobra venom factor only group (GV-CVF 47 +/- 2 neutrophils/high-power field), reductions in neutrophil count were observed in all groups (neutrophils/high-power field): PLV-CVF (20 +/- 2, p = .009); PEEP-CVF (24 +/- 1, p = .01); CVF-PLV (30 +/- 2, p = .03); and CVF-PEEP (37 +/- 1, p = .04).

CONCLUSION

These data suggest that both partial liquid ventilation and PEEP result in a reduction in neutrophil accumulation in the setting of acute lung injury.

Partial liquid ventilation decreases albumin leak in the setting of acute lung injury

PURPOSE

This study evaluated the ability of partial liquid ventilation (PLV, gas ventilation of the perfluorocarbon-filled lungs) to reduce the amount of lung albumin leak present in the setting of acute lung injury.

MATERIALS AND METHODS

An experimental controlled, randomized design was used. All studies were performed in the liquid ventilation laboratories at the University of Michigan Medical Center. Twenty-five Sprague-Dawley male rats 500+/-50 g were divided into five experimental groups: (1) CVF only (n=5), animals were cobra venom factor (CVF) lung injured; (2) PLV-CVF (n=5) animals received perflubron and PLV before CVF lung injury; (3) CVF-PLV (n=5) animals received PLV after CVF lung injury; (4) PLV only (n=5) animals underwent partial liquid ventilation without lung injury; and (5) Gas only (n=5) animals underwent gas ventilation without lung injury. In all groups iodinated bovine serum albumin (125I-BSA) was delivered by intravenous injection along with CVF or a saline placebo.

RESULTS

When the CVF animals were compared with all other groups, a decrease in albumin leak was observed for all groups when compared with the CVF only controls (P < .001 by ANOVA; CVF only=1.22+/-0.12 versus PLV-CVF=0.46+/-0.08, P < .001; CVF-PLV=0.70+/-0.25, P < .001; PLV only=0.22+/-0.01, P < .001; Gas only=0.17+/-0.02, P < .001).

CONCLUSIONS

These data suggest that intratracheal instillation of perfluorocarbon before or after induction of lung injury results in a reduction in pulmonary albumin leak.

Cytokine and adhesion molecule requirements for lung injury induced by anti-glomerular basement membrane antibody

Acute hemorrhagic lung injury occurs in humans with anti-GBM antibody (Goodpasture's syndrome), however, the mechanism of this injury is still largely unknown. To date, treatment has been confined to steroids and plasmaphoresis. Infusion of anti-GBM antibody into rats caused lung injury with intra-alveolar hemorrhage and intrapulmonary accumulation of neutrophils. Lung injury was dependent on the presence of neutrophils and complement and required both TNF alpha and IL-1. Experiments employing blocking antibodies to adhesion molecules demonstrated requirements for the beta 1 integrin VLA-4, beta 2 integrins LFA-1 and Mac-1, and L-selection. The endothelial cell adhesion molecules, E-selectin and ICAM-1, were also required for the full development of lung injury. Inhibition of TNF alpha or IL-1 or adhesion molecules reduced both lung injury and tissue neutrophil accumulation. Thus, this study underscores cytokine and adhesion molecule requirements for neutrophil mediated injury in lung and kidney caused by anti-GBM, suggesting potential targets for the treatment of Goodpasture's syndrome in humans.

The pattern of early lung parenchymal and air space injury following acute blood loss

Acute lung injury is a frequent clinical occurrence following blood loss and trauma. The nature of this injury remains poorly understood.

OBJECTIVE

To examine the relative parenchymal and intra-alveolar distribution of inflammation in a rat model of hemorrhage and resuscitation.

METHODS

Rats were anesthetized and subjected to hemorrhage followed by resuscitation with shed blood and saline. Myeloperoxidase activity of lung homogenates and cytology of bronchoalveolar lavage fluid were used to measure total lung and intra-alveolar neutrophil invasion. Extravasation of i.v.-administered [125I]-albumin was used to determine total lung and alveolar permeability. Permeability results were analyzed using their base-10 logarithmic transformations.

RESULTS

86 animals were studied. Whole-lung myeloperoxidase activity was increased (control = 0.34 +/- 0.16 units, injured = 0.84 +/- 0.43 units, p < 0.01), while there was no difference in intra-alveolar leukocyte counts (injured = 1.85 +/- 1.30 x 10(5)/mL, control = 2.44 +/- 1.75 x 10(5)/mL, p = 0.40), suggesting that the cellular component of the injury was more severe in the intravascular and interstitial spaces. There was a strong trend toward increased permeability in the interstitial compartment, and a significant increase in permeability in the intra-alveolar compartment (whole-lung permeability: control = -0.27 +/- 0.19 units, injured = 0.10 +/- 0.55 units, p = 0.06; alveolar permeability: control = -2.00 +/- 0.47 units, injured = -1.32 +/- 0.49 units, p < 0.01), suggesting that the loss of integrity to macromolecules was not limited to the interstitium.

CONCLUSION

Hemorrhage and resuscitation resulted in an acute lung injury characterized by extravasation of intravascular protein into both the interstitium and the intra-alveolar space. Neutrophil invasion of the lung was demonstrable only in the interstitial compartment.

Reactive oxygen species contribute to oxygen-related lung injury after acid aspiration

Hyperoxia increases pulmonary damage after acid aspiration. We hypothesize that free radicals play a role in acute lung injury. To examine this hypothesis, we injured rats by intratracheal instillation of acidic isotonic sodium chloride solution (NS) (pH 1.25); NS + gastric particles (particle pH 5.3); or acid + particles (pH 1.25). Animals were exposed to 98% oxygen or air for 5 h. Superoxide (HO2) generation was measured in either an aliquot of white blood cells (WBCs) recovered from bronchoalveolar lavage (BAL) or from blood. Lungs were analyzed for thiobarbituric acid-reactive substances (TBARS) and carbonylated proteins. The antioxidant capacity was measured using a 2-2'-azo-bis-amidinopropane hydrochloride neutralizing assay. Generation of HO2 by WBCs in peripheral blood was greater in animals exposed to 98% O2 (89.8 +/- 12.5 U. min-1.10(5) neutrophils) compared with air exposure (37.5 +/- 9.2 U.min-1.10(5) neutrophils) after combined injury (P < 0.05). Similarly, HO2 generation by WBCs retrieved from BAL was higher in oxygen-exposed rats (987.74 +/- 128 U.min-1.10(5) WBC) compared with air-exposed animals after an identical injury (348 +/- 9.2 U. min-1.10(5) WBC) (P < 0.05). TBARS and carbonylated protein levels in the lungs of oxygen-exposed animals (587.9 +/- 58.6 and 55.8 +/- 3.1 pmol/mg of protein, respectively) were higher than those in air-exposed rats after combined injury (342.8 +/- 15.1 and 28.6 +/- 4.6 pmol/mg of protein, respectively) and compared with air-exposed uninjured rats (340.6 +/- 9.8 and 18.3 +/- 2.8 pmol/mg of protein, respectively; P < 0.01). Antioxidant capacity decreased in acid and combined injury groups (2.41 +/- 0.13 min and 1.94 +/- 0.15 min, respectively) compared with the uninjured group after 5 h of exposure to 98% oxygen (4.85 +/- 0.19 min; P < 0.01). We demonstrated evidence of increased oxidant activity on lipids and proteins in injured lungs after oxygen exposure. The decrease in antioxidant capacity after low pH aspiration with exposure to hyperoxia may contribute to this increase.

IMPLICATIONS

Oxygen administration results in a lung pathology known as oxygen toxicity. This effect is usually not significant if the duration of exposure is limited to < 24 h. In the presence of acute inflammatory lung injury, exposure to hyperoxia results in lung damage in a shorter time. We demonstrate that sufficiently decreased lung antioxidant reserve capacity may be accountable for this early toxicity.

Over expression of the murine myotonic dystrophy protein kinase in the mouse myogenic C2C12 cell line leads to inhibition of terminal differentiation

Myotonic dystrophy (DM) is an autosomal dominant human disorder, caused by the abnormal expansion of a CTG trinucleotide repeat in the 3' untranslated region of a protein kinase gene (DMPK). Muscle symptoms are a common feature of the disorder and in the adult onset cases there are increased patterns of muscle fibre degeneration and regeneration. In the congenitally affected infants there is a failure of muscle maturation, with the histological presence of numerous immature fibres. However, the pathological mechanism in both forms of the disease is unclear. We report that over-expression of the murine dmpk gene, in a murine myogenic cell line, leads to markedly reduced levels of fusion to the terminally differentiated state. These findings complement recently published data using a heterologous expression/cell system and may have implications for the understanding of the disease process in this disorder.

The effect of inhaled nitric oxide therapy on bleeding time and platelet aggregation in neonates

The effect of inhaled nitric oxide (iNO) on bleeding time and platelet aggregation was studied in nine newborn infants with resolving pulmonary hypertension. Infants treated with iNO at 40 ppm for 30 minutes had bleeding times that were nearly twofold longer than those obtained 24 hours after iNO was discontinued. iNO had no effect on in vitro platelet aggregation studies.

SP1/SP3-binding sites and adjacent elements contribute to basal and cyclic adenosine 3',5'-monophosphate-stimulated transcriptional activation of the rhesus growth hormone-variant gene in trophoblasts

Transcriptional activation of the rhesus monkey GH-variant gene in syncytiotrophoblasts is developmentally regulated by trophoblast-specific and cAMP-responsive mechanisms. Progressive deletions of 5'-flanking DNA defined the most proximal 140 bp as the minimal region retaining full cAMP-stimulated mGH-V transcription. To identify the regions of this promoter critical for transcription, transient transfections of reporter plasmids containing systematic 10 base mutations throughout this proximal region were performed. Mutation of the region from -140/-131 decreased transcription in syncytiotrophoblasts by 50%, and gel mobility-shift analyses demonstrated that Sp1 and Sp3 bound to a region containing a GGGAGG motif at -136/-131. Mutation of the -62/-53 region decreased transcriptional activation by 66-99%, and Sp1 and Sp3 bound to a GGTGGG motif overlapping this region (at -65/-60). Selective mutation of this Sp1/Sp3 site decreased basal transcription by approximately 80%, and cAMP-stimulated transcription by up to 75% (with the greatest effect in primary syncytiotrophoblast cultures), indicating that the Sp1/Sp3 site is critical for transcriptional activation. Mutations in the regions adjacent to the Sp1/Sp3 sites (-130/-111 and -52/-43) also dramatically reduced (by 75%) transcriptional activation in trophoblasts. We conclude that two Sp1/Sp3 sites as well as additional elements directly adjacent to these sites contribute to trophoblast-specific cAMP-responsiveness of the mGH-V proximal promoter.

Progression of somatic CTG repeat length heterogeneity in the blood cells of myotonic dystrophy patients

The genetic basis of myotonic dystrophy (DM) is the expansion of an unstable CTG repeat in the 34 UTR of the DM protein kinase gene on chromosome 19. One of the principal features of the DM mutation is an extraordinarily high level of somatic mosaicism, due to an extremely high degree of somatic instability both within and between different tissues. This instability appears to be biased towards further expansion and continuous throughout the life of an individual, features that could be associated with the progressive nature of the disease. Although increasing measured allele size between patients clearly correlates with an increased severity of symptoms and an earlier age of onset, this correlation is not precise and measured allele length cannot be used as an accurate predictor of age of onset. In order to further characterize the dynamics of DM CTG repeat somatic instability, we have studied repeat length changes over time in 111 myotonic dystrophy patients with varying clinical severity and CTG repeat size over time intervals of 1-7 years. We have found a direct progression of the size heterogeneity over time related to initial CTG repeat size and the time interval and always biased towards further expansion. Attempts to mathematically model the dynamics have proved only partially successful suggesting that individual specific genetic and/or environmental factors also play a role in somatic mosaicism.

Alterations in the course of acid-induced lung injury in rats after general anesthesia: volatile anesthetics versus ketamine

Pulmonary aspiration of gastric acid is a complication that occurs during anesthesia. The effects of the often used anesthetics on the inflammatory response after aspiration of acid are not known. We examined the effects of three different inhaled anesthetics--halothane, enflurane, and isoflurane--as well as parenteral ketamine, on the associated immediate mortality, alveolar protein leakage, and morphometric changes after intrapulmonary instillation of acidic solution in rats. Animals in deep state of anesthesia had a higher mortality after the instillation of acidic solutions than those in lighter stages (82.5% vs 31.6%). Protein leakage over 5 h was greater in the animals receiving volatile anesthetics (range 0.9-1.2) compared with those receiving ketamine (0.6 +/- 0.05). Desferoxamine did not decrease protein leakage in acid-injured animals (1.1 +/- 0.06 vs 1.02 +/- 0.08). Furthermore, volatile anesthetics resulted in an increase in the acute inflammatory response and leukocytic infiltration compared with ketamine in acid-injured lungs. We conclude that the administration of inhaled anesthetics was associated with exacerbation of an acute inflammatory response after aspiration of acidic solution. Lung injury was not increased with ketamine anesthesia. This difference was the result of the hypotensive effects of inhaled anesthetics.

IMPLICATIONS

This study reveals that the use of inhaled anesthetics aggravates inflammation secondary to gastric aspiration and should be avoided on diagnosis of the situation.

Regional workload induced changes in electrophysiology and immediate early gene expression in intact in situ porcine heart

Cardiac remodelling and hypertrophy induced by chronic haemodynamic overload (stretch) eventually leads to a decrease in cardiac function, an increased incidence of ventricular arrhythmia and mortality. The mechanisms by which myocytes sense haemodynamic stress and activate growth signals are largely unknown. Nuclear immediate early genes may act as third messengers, converting the stretch stimulus into long-term changes of gene expression via cytoplasmic signal transduction. However, previous studies have used cell cultures and isolated hearts, neither of which are ideal models. We have developed a new in situ porcine heart model where local strain (stretch) can be applied, for several hours if required, thus allowing the comparison of changes in electrophysiology and gene expression with unstrained myocardium in the same preparation. A pneumatically controlled stretch-device was attached to a portion of the right ventricle of an anaesthetized animal using suction. Chronic stretch was applied for 30 min or 1 h. Regional loading produced (i) a transient decrease in monophasic action potential duration (3.5+/-0.8%; P<0.05), followed by (ii) an elongation by 15 min, despite maintained stretch (3.4+/-1.5%; P<0.05 compared to the pre-stretch situation). A control segment of the right ventricle did not show these changes. Northern blot analysis showed that both c-fos and c-myc were induced in the areas sampled, but they were 12-fold and three-fold higher, respectively, in stretched compared with control tissue after 30 min. Thus, prolonged regional stretch can produce complex changes in cardiac electrophysiology and increase expression of some immediate early genes. Our model may be useful for studying the cascade of events that lead to remodelling, hypertrophy, and arrhythmia.