Paramediastinal air cyst with traumatic bronchial injury: a rare complication of neonatal resuscitation.

Paramediastinal air cysts and pneumatoceles are known complications of chest trauma and mechanical ventilation. After an initial period of enlargement, these lesions tend to resolve completely with conservative management. We present a case of a premature newborn who developed an enlarging paramediastinal air cyst as a result of resuscitation around the time of delivery that ultimately required surgical excision via a right thoracotomy. To our knowledge, this is the first reported case in a neonate.

Intramural hematoma of the aorta: delayed pericardial tamponade.

Intramural hematoma of the aorta is a fatal disorder that remains poorly characterized. Recently, it has been accepted as a variant form of aortic dissection, where blood accumulates within the aortic media without the presence of an intimal tear. Clinically, it may present somewhat similar to dissection, and although optimal therapy remains controversial, current opinion supports surgery as the preferred method of treatment for intramural hematomas that involve the ascending aorta and aortic arch.

Idiopathic pulmonary artery aneurysm.

Pulmonary artery aneurysm is a rare clinical condition. It is known to be associated with certain congenital or acquired conditions, yet its etiology is not well understood. Its diagnosis is often not challenging. However, controversy still remains regarding its treatment. We report a case of idiopathic pulmonary artery aneurysm treated by surgical correction.

Involvement of p38 mitogen-activated protein kinase in the induction of tolerance to hemorrhagic and endotoxic shock.

BACKGROUND: Exposure to sublethal hemorrhage (SLH) makes rats tolerant to subsequent hemorrhagic or septic shock and is associated with altered NF-kappaB activity. The purpose of this study was to explore whether changes in p38 mitogen-activated protein (MAP) kinase activity also occur in the induction of tolerance by SLH. METHODS: Rats were made tolerant by SLH or sham operation. Twenty-four hours later rats were exposed to lipopolysaccharide (LPS) or had peritoneal macrophages (Mphi) isolated. CNI-1493, a p38 MAP kinase inhibitor, or saline was given prior to SLH. Lungs were harvested 1 h after SLH or LPS and total protein was extracted. Peritoneal Mphi were stimulated with LPS (10 microg/ml) and total protein was isolated 1 h later. Active, dually phosphorylated p38 MAP kinase was determined by Western blot. Tumor necrosis factor (TNF) was measured in Mphi supernatants by enzyme-linked immunosorbent assay (ELISA) 18 h after LPS. RESULTS: SLH activated p38 MAP kinase in the lung and this was inhibited by CNI-1493. Twenty-four hours later, lung p38 MAP kinase activity increased to the same degree in tolerant and sham rats following LPS, but much more prominently in the CNI-1493 treated rats. There was no p38 activity in peritoneal Mphi at baseline, and similar to lung p38, LPS led to increased p38 activity which was most significant in Mphi from rats that received CNI-1493 prior to SLH. TNF production by tolerant Mphi in response to LPS was significantly (P < 0.05, t test) decreased and p38 inhibition with CNI-1493 at the time of SLH reversed the inhibitory effects of tolerance on TNF production. CONCLUSIONS: TNF production by tolerant Mphi following a second insult (LPS) is attenuated despite preservation of normal p38 MAP kinase activity. However, activation of this intracellular second messenger is a necessary step in the "cellular reprogramming" that occurs during the induction of tolerance by SLH.

Differential expression of transforming growth factor beta receptors in human pancreatic adenocarcinoma.

BACKGROUND: Many cancer cells show resistance to transforming growth factor beta (TGF-beta)-mediated growth inhibition. This resistance to TGF-beta is associated with an increased tumorigenic phenotype. OBJECTIVE: In this study, we determined whether a loss in expression of TGF-beta receptors or DPC4, an important down stream target of TGF-beta signaling, might account for this lack of TGF-beta sensitivity in pancreatic adenocarcinoma. MATERIALS AND METHODS: To accomplish this, six established pancreatic cancer cell lines, twenty-six surgically resected tumor specimens of pancreatic adenocarcinoma and ten non-tumor pancreas tissues were analyzed for the mRNA expression of the three TGF-beta receptors (RI, RII, and RIII) and DPC4. RESULTS: We report here that five of six pancreatic cancer cell lines were not sensitive to TGF-beta. All the ten non-tumor specimens of pancreas showed expression of RI, and DPC4; while nine of ten showed expression of RIII and eight of ten showed expression of RII. Five of six pancreatic cancer cell lines and 23 of 26 tumor specimens showed expression of RI. Two cell lines and about half (46%) of the tumor specimens did not express RII. Only two cell lines showed appreciable levels of RIII expression; while ten of 26 (38%) tumor specimens did not show expression of RIII. DPC4 expression was observed in three of the six (50%) cell lines and 19 of 24 (79%) tumor specimens. CONCLUSION: This study indicates that apart from the functional loss of DPC4 due to mutations or homozygous deletion, a lack of the TGF-beta receptors, particularly RII and RIII, may contribute to a loss of TGF-beta signaling in a population of pancreatic cancers.

Regulation of atrial natriuretic peptide gene expression in gastric antrum by fasting.

Atrial natriuretic peptide (ANP) gene expression was localized in the rat gastric antrum using immunohistochemistry and in situ hybridization to mucosal cells in the lower portion of the antropyloric glands. Colocalization of immunoreactive ANP, long-acting natriuretic peptide, i.e., proANP-(1-30), and serotonin in these cells identified them to be enterochromaffin cells. Fasting for 72 h in 8-mo-old (adult) rats produced a significant (P < 0.05) decrease in the levels of ANP prohormone mRNA, immunoreactive proANP-(1-30) and ANP to approximately 33% of that of fed rats. Fasting in 1-mo-old rats had no effect on these parameters. Transcripts for natriuretic peptide receptor subtypes NPR-A, NPR-B, and NPR-C were found in both mucosa and muscle tissues of the antrum. ANP, brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) stimulated the production of cGMP in antral mucosa in vitro with a potency of ANP > BNP >> CNP, suggesting that these receptors were functional. We conclude that fasting decreases ANP prohormone mRNA and its gene products, long-acting natriuretic peptide, and ANP in the antrum of adult rats.

Matrix metalloproteinase inhibition improves survival in an orthotopic model of human pancreatic cancer.

Matrix metalloproteinases (MMPs) have been implicated in the growth and invasiveness of primary and metastatic tumors. Hypothesizing that MMP inhibition would slow cancer growth, the MMP inhibitor BB-94 (batimistat) was evaluated in an orthotopic animal model of human pancreatic carcinoma. Ten million human pancreatic cancer cells were surgically implanted into the pancreata of 30 athymic nu/nu mice. Intraperitoneal administration of 30 mg/kg BB-94 or vehicle control began 7 days after tumor implantation (13 mice with confirmed implantations in each group) and continued daily for 21 days, and then three times weekly until death or sacrifice at day 70. Representative tumors harvested from mice in each group were analyzed for presence and activity of MMP-2 and MMP-9. Animal weights were significantly higher in the BB-94-treated group at sacrifice (mean 58.4 +/- 7.9 g vs. 39.8 +/- 6.2 g; P < 0.05, Student's t test). The likelihood of survival to 70 days was significantly higher in the treated group (4 of 13 vs. 0 of 13, P < 0.05, Z-test for end points) than in the control group as was overall survival (P = 0.03, Wilcoxon test). Nine mice in the control group developed metastases to the liver, peritoneum, abdominal wall, or local lymph nodes, whereas only two mice in the BB-94 group had evidence of metastatic disease (P < 0.02, Fisher's exact test), in both instances confined to the abdominal wall. Tumors from treated mice manifested lower MMP activity than those from control animals. These reports support the use of MMP inhibitors alone or as an adjunct in the treatment of pancreatic cancer.

Renal ischemia/reperfusion leads to macrophage-mediated increase in pulmonary vascular permeability.

BACKGROUND: Despite the advent of dialysis, survival with acute renal failure when associated with multiorgan failure is poor. The development of lung injury after shock or visceral ischemia has been shown; however, the effects of isolated renal ischemia/reperfusion injury (IRI) on the lungs are unclear. We hypothesized that isolated renal IRI could alter pulmonary vascular permeability (PVP) and that macrophages could be important mediators in this response. METHODS: Rats (N = 5 per group) underwent renal ischemia for 30 minutes, followed by reperfusion. Lung vascular permeability was evaluated by quantitation of Evans blue dye extravasation from vascular space to lung parenchyma at 1, 24, 48, or 96 hours after reperfusion. Serum was collected for blood urea nitrogen and creatinine at each time point. To examine the role of the macrophage, the macrophage pacifant CNI-1493, which inhibits the release of macrophage-derived inflammatory products, was administered in a blinded fashion during renal IRI. RESULTS: PVP was significantly (P < 0.05) increased at 24 hours and peaked at 48 hours after IRI compared with shams as well as baseline levels. PVP after IRI became similar to shams after 96 hours. This correlated with increases in blood urea nitrogen and creatinine at similar time points. At 48 hours, CNI-1493 significantly abrogated the increase in PVP compared with IRI alone. However, CNI-1493 did not alter the course of the acute renal failure. Pulmonary histology demonstrated interstitial edema, alveolar hemorrhage, and red blood cell sludging after renal IRI, which was partially attenuated by CNI-1493. CONCLUSIONS: Increased PVP develops after isolated renal IRI, and macrophage-derived products are mediators in this response. These findings have implications for understanding the mechanisms underlying respiratory dysfunction associated with acute renal failure.

Tolerance to shock: an exploration of mechanism.

OBJECTIVE: To determine if cross-tolerance to septic shock could be induced by a previous insult with sublethal hemorrhage (SLH) and to characterize the mechanisms involved in this induced protective response. BACKGROUND DATA: It is possible to condition animals by prior SLH such that they tolerate an otherwise lethal hemorrhage. It is also possible to condition animals with low doses of lipopolysaccharide (LPS) so that they survive a "lethal" septic insult. However, a paucity of information exists on cross-tolerance between hemorrhage and sepsis. METHODS: Rats were made tolerant by conditioning SLH or sham operation. Twenty-four hours later, tolerant and sham rats were exposed to a lethal dose of LPS. To explore the mechanism of tolerance induction, rats were given the macrophage (Mphi) inhibitor CNI-1493 or saline carrier before SLH. Survival and pulmonary vascular injury were determined after LPS. Serum tumor necrosis factor (TNF) levels and splenic Mphi TNF gene expression were measured at several time points. RESULTS: Prior SLH indeed made rats tolerant and imparted a significant survival benefit and reduction in pulmonary vascular injury after LPS. The tolerance induced by SLH was reversed by Mphi inhibition. Tolerant animals had low serum TNF levels immediately after SLH and reduced circulating TNF levels after LPS. SLH, however, did not inhibit the augmentation of TNF gene expression after LPS. CONCLUSIONS: Sublethal hemorrhage bestows protection against a lethal LPS challenge. Inhibition of the Mphi attenuated the benefit of the tolerance induced by SLH. Circulating TNF but not TNF gene after LPS is lessened by SLH. This implicates changes in Mphi intracellular signaling in induction of the tolerant state.

Induction of tolerance to hemorrhagic or endotoxic shock involves activation of NF-kappaB.

BACKGROUND: Tolerance to hemorrhagic or endotoxic shock can be induced by prior sublethal hemorrhage (SLH). The purpose of this study was to explore whether alterations in signal transduction pathways involving NF-kappaB occur in macrophages (Mphi) following induction of tolerance by SLH. METHODS: Using a model of SLH previously shown in our lab to impart a survival benefit to subsequent hemorrhagic or endotoxic shock, rats (n = 30) were conditioned by SLH. Peritoneal Mphi were harvested 24 h after conditioning and stimulated with lipopolysaccharide (LPS) (10 microg/mL). Nuclear and cytosolic proteins were isolated 1 h later for determination of NF-kappaB activation by gel-shift assay and IkappaB-alpha by Western blot. TNF mRNA gene expression was measured 4 h after LPS stimulation by reverse transcription/polymerase chain reaction (RT/PCR). TNF protein levels were measured in cellular supernatants by enzyme-linked immunosorbent assay (ELISA) 18 h after LPS. RESULTS. LPS stimulation of sham Mphi increased NF-kappaB activation with corresponding loss of its inhibitor IkappaB-alpha. In contrast, IkappaB-alpha was not detectable following conditioning, and conditioned Mphi had NF-kappaB activation at baseline which increased minimally with LPS stimulation. LPS increased TNF gene expression and significantly increased protein production by both sham and conditioned Mphi, but this increase was greater in the sham-conditioned group. CONCLUSIONS: The ability of Mphi from animals made tolerant by SLH to produce TNF in vitro is conserved. Nevertheless, these same Mphi exhibit alterations in TNF gene induction and expression as well as signal transduction, specifically, changes in IkappaB-alpha and NF-kappaB activation. This suggests a role for activation of NF-kappaB in the induction of tolerance.

Sublethal hemorrhage blunts the inflammatory cytokine response to endotoxin in a rat model.

BACKGROUND: Tolerance to lipopolysaccharide (LPS) induced by previous hemorrhage in mice is associated with a blunted interleukin 1 (IL-1) response, suggesting down-regulation of the cytokine cascade as a possible protective mechanism. This study was undertaken to determine whether prehemorrhage induces attenuation of the cytokine response to sepsis beyond IL-1 in a rat model and whether this response occurs at the level of gene transcription. METHODS: Sprague-Dawley rats underwent sublethal hemorrhage, lethal intraperitoneal endotoxin, or sublethal hemorrhage with delayed lethal endotoxin. Animals were killed 12 hours after LPS injection or 24 hours after hemorrhage. IL-1 and tumor necrosis factor (TNF) mRNA levels were determined on total splenic RNA using reverse-transcriptase polymerase chain reaction, and serum cytokine levels were determined using enzyme-linked immunosorbent assay. RESULTS: Animals that received LPS alone mounted an IL-1 and TNF response (RNA and protein) much higher than animals subjected to hemorrhage alone. TNF and IL-1 gene expression and protein levels in prehemorrhaged animals that received LPS, however, were significantly lower than those of animals that received LPS alone. CONCLUSION: Hemorrhage induces early IL-1 and TNF gene expression, which blunts their subsequent expected increase after endotoxic challenge. These findings validate previously documented immune-modulated protective effects of the first insult in a two-hit model.

The physiologic consequences of macrophage pacification during severe acute pancreatitis.

Macrophage overproduction of inflammatory mediators is detrimental in the progression of acute pancreatitis. Although inhibition of inflammatory mediators has been shown to decrease the severity of experimental pancreatitis and improve overall survival, less is known about the mechanism by which blockade produces these benefits. Prior to the induction of lethal acute pancreatitis, rats were randomized to receive a single dose (.01, .1, 1.0, or 10 mg/kg) of a macrophage-pacifying compound (CNI-1493) or vehicle. Escalating doses provided incremental increases in survival from 10% (vehicle) to a maximum of 70% (CNI-1493, 1.0 mg/kg). To evaluate the physiologic mechanism responsible for the improved survival, continuous arterial blood pressure, serial hematocrit, ascites volume, pancreatic edema, bronchoalveolar leukocytes and protein, and pancreatic histology were determined in additional rats receiving CNI-1493 (1.0 mg/kg). Serum tumor necrosis factor-alpha and nitrites were also determined to assess the mechanism of action of CNI-1493. Macrophage pacification decreased pancreatitis severity as determined by enzyme release and pancreatic histology score. Ascites volume and bronchoalveolar protein levels were also decreased, indicating that CNI-1493 prevents the loss of circulating blood volume and maintains hematocrit and mean arterial pressure, thus improving survival. CNI-1493 prevented the increase of serum tumor necrosis factor-alpha but not serum nitrites, implicating macrophage-derived cytokines and not nitric oxide in the pathogenesis of physiologic decompensation and death in this model of pancreatitis.