Heparin reduces overcirculation-induced pulmonary artery remodeling through p38 MAPK in piglet.

BACKGROUND: Artery remodeling is the principal change of pulmonary artery hypertension. Heparin has been shown to inhibit vascular smooth muscle cell proliferation. We hypothesized that heparin may modulate vascular remodeling in pulmonary artery hypertension, and explored the mechanism. METHODS: A localized overcirculation-induced artery remodeling was created in piglets by anastomosing the left lower lobe pulmonary artery (LLLPA) to the thoracic aortic artery. Piglets were treated with heparin or saline for 4 weeks. Hemodynamic data were collected, and histology of the lung was assessed. We investigated the expressions of several candidate genes in lung and further observed the involvement of P38 mitogen-activated protein kinases (MAPK). The effects of heparin on the growth of cultured pulmonary arterial vascular smooth muscle cell and P38 MAPK expression were further determined under various conditions. RESULTS: Four weeks after the shunt setup, overcirculation caused significant LLLPA remodeling, pressure increase, and pulmonary vascular resistance increase, and LLLPA flow reduction compared with that immediately after the shunt setup. Heparin reduced the LLLPA remodeling, pressure, and pulmonary vascular resistance, and increased the LLLPA flow compared with that not heparin treated. Shunt and heparin treatment did not change the piglet's systemic hemodynamics. Shunt increased the expression of P38 MAPK and heparin decreased its expression in the shunted LLLPA. Both heparin and P38 MAPK inhibitor suppressed VSMC growth and P38 MAPK expression in the cultured VSMC, but they did not present additive effects when the two treatments were combined. CONCLUSIONS: Heparin reduces overcirculation-induced pulmonary artery remodeling through a P38 MAPK-dependent pathway.

Signal quality of single dose gadobenate dimeglumine pulmonary MRA examinations exceeds quality of MRA performed with double dose gadopentetate dimeglumine.

During a recent multi-center trial assessing gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) for diagnosis of acute pulmonary embolism (PE), the Food and Drug Administration announced a risk of nephrogenic sclerosing fibrosis in patients with renal insufficiency who had received intravenous Gd-based MR contrast agents. Although no patients in this trial had renal insufficiency, in cautious response to this announcement, the trial protocol was changed from an intravenous administration of 0.2 mmol/Kg of a conventional Gd-based MR contrast agent to 0.1 mmol/Kg of gadobenate dimeglumine. The study described herein compares the signal quality of pulmonary MRA performed with double dose conventional agent to single dose gadobenate dimeglumine. This study is a retrospective analysis of data from a prospective, multicenter study in men and women ≥18 years with documented presence or absence of PE. The study was approved by the Institutional Review Board at all participating centers, and all patients provided written indication of informed consent. We performed both objective and subjective analysis of pulmonary artery image quality. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the main pulmonary artery were assessed in single and double dose protocols and compared. SNR and CNR of the main PA were correlated with subjective quality assessment of main/lobar, segmental and subsegmental pulmonary arteries. Although there were individual outliers, both SNR (P = 0.01) and CNR (P = 0.008) were higher in all quartiles for examinations using gadobenate dimeglumine than with gadopentetate dimeglumine. Subjective quality of vascular signal intensity at each vessel order was significantly better for gadobenate dimeglumine (P < 0.0001), and correlated well with SNR and CNR at each order (<0.001). Because of agent high relaxivity, a single dose of gadobenate dimeglumine provides better pulmonary MRA signal quality than double dose of a conventional Gd-based MR contrast agent.

Comparison of 1.5 and 3.0 T for contrast-enhanced pulmonary magnetic resonance angiography.

OBJECTIVE: In a recent multi-center trial of gadolinium contrast-enhanced magnetic resonance angiography (Gd-MRA) for diagnosis of acute pulmonary embolism (PE), two centers utilized a common MRI platform though at different field strengths (1.5T and 3T) and realized a signal-to-noise gain with the 3T platform. This retrospective analysis investigates this gain in signal-to-noise of pulmonary vascular targets. METHODS: Thirty consecutive pulmonary MRA examinations acquired on a 1.5T system at one institution were compared to 30 consecutive pulmonary MRA examinations acquired on a 3T system at a different institution. Both systems were from the same MRI manufacturer and both used the same Gd-MRA pulse sequence, although there were some protocol adjustments made due to field strength differences. Region-of-interests were manually defined on the main pulmonary artery, 4 pulmonary veins, thoracic aorta, and background lung for objective measurement of signal-to-noise, contrast-to-noise, and bolus timing bias between centers. RESULTS: The 3T pulmonary MRA protocol achieved higher spatial resolution yet maintained significantly higher signal-to-noise ratio (≥13%, p = 0.03) in the main pulmonary vessels relative to 1.5T. There was no evidence of operator bias in bolus timing or patient hemodynamic differences between groups. CONCLUSION: Relative to 1.5T, higher spatial resolution Gd-MRA can be achieved at 3T with a sustained or greater signal-to-noise ratio of enhanced vasculature.

Factors in the technical quality of gadolinium enhanced magnetic resonance angiography for pulmonary embolism in PIOPED III.

In a multi-center trial, gadolinium enhanced magnetic resonance angiography (MRA) for diagnosis of acute pulmonary embolism (PE) had a high rate of technically inadequate images. Accordingly, we evaluated the reasons for poor quality MRA of the pulmonary arteries in these patients. We performed a retrospective analysis of the data collected in the PIOPED III study. We assessed the relationship to the proportion of examinations deemed "uninterpretable" by central readers to the clinical centers, MR equipment platform and vendors, degree of vascular opacification in different orders of pulmonary arteries; type, frequency and severity of image artifacts; patient co-morbidities, symptoms and signs; and reader characteristics. Centers, MR equipment vendor and platform, degree of vascular opacification, and motion artifacts influenced the likelihood of central reader determinations that images were "uninterpretable". Neither the reader nor patient characteristics (age, body mass index, respiratory rate, heart rate) correlated with the likelihood of determining examinations "uninterpretable". Vascular opacification and motion artifact are the principal factors influencing MRA interpretability. Some centers obtain better images more consistently, but the reasons for differences between centers are unclear.

Low molecular weight hyaluronan, via AP-1 and NF-κB signalling, induces IL-8 in transformed bronchial epithelial cells.

QUESTIONS UNDER STUDY: New evidence demonstrated that high tidal volume mechanical ventilation results in substantial bronchial airway mechanical strain. In addition, high tidal volume mechanical ventilation has been shown to increase IL-8 production in a mechanism mediated, at least in part, by low molecular weight hyaluronan (LWM-HA). In the present study, it was investigated whether LMW-HA synthesised in the lung, in response to cyclic stretch, increased IL-8 production in the bronchial epithelium. METHODS: This question was approached by stimulating a transformed human bronchial epithelial cell line with LMW-HA isolated from stretched human lung fibroblasts and probed for the activation of extracellular signal-regulated kinase pathways. RESULTS: LMW-HA increased IL-8 secretion in transformed bronchial epithelial cells. Additionally, LMW-HA augmented the levels of phospho c-Jun NH2-terminal kinase (JNK) and phospho extracellular signal-regulated kinase 1/2 (ERK1/2), and also mobilised nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) from the cytoplasm to the nucleus. The inhibition of JNK, ERK1/2 and NF-κB blocked IL-8 secretion in response to LMW-HA. CONCLUSION: The data suggest that LMW-HA produced by lung fibroblasts in response to cyclic stretch increases the secretion of IL-8 in transformed bronchial epithelial cells via AP-1 and NF-κB signalling pathways. These findings support the hypothesis that LMW-HA plays an active role in acute lung inflammation triggered by mechanical strain.

Long-term exposure to hypoxia inhibits tumor progression of lung cancer in rats and mice.

BACKGROUND: Hypoxia has been identified as a major negative factor for tumor progression in clinical observations and in animal studies. However, the precise role of hypoxia in tumor progression has not been fully explained. In this study, we extensively investigated the effect of long-term exposure to hypoxia on tumor progression in vivo. METHODS: Rats bearing transplanted tumors consisting of A549 human lung cancer cells (lung cancer tumor) were exposed to hypoxia for different durations and different levels of oxygen. The tumor growth and metastasis were evaluated. We also treated A549 lung cancer cells (A549 cells) with chronic hypoxia and then implanted the hypoxia-pretreated cancer cells into mice. The effect of exposure to hypoxia on metastasis of Lewis lung carcinoma in mice was also investigated. RESULTS: We found that long-term exposure to hypoxia a) significantly inhibited lung cancer tumor growth in xenograft and orthotopic models in rats, b) significantly reduced lymphatic metastasis of the lung cancer in rats and decreased lung metastasis of Lewis lung carcinoma in mice, c) reduced lung cancer cell proliferation and cell cycle progression in vitro, d) decreased growth of the tumors from hypoxia-pretreated A549 cells, e) decreased Na+-K+ ATPase α1 expression in hypoxic lung cancer tumors, and f) increased expression of hypoxia inducible factors (HIF1α and HIF2α) but decreased microvessel density in the lung cancer tumors. In contrast to lung cancer, the growth of tumor from HCT116 human colon cancer cells (colon cancer tumor) was a) significantly enhanced in the same hypoxia conditions, accompanied by b) no significant change in expression of Na+-K+ ATPase α1, c) increased HIF1α expression (no HIF2α was detected) and d) increased microvessel density in the tumor tissues. CONCLUSIONS: This study demonstrated that long-term exposure to hypoxia repressed tumor progression of the lung cancer from A549 cells and that decreased expression of Na+-K+ ATPase was involved in hypoxic inhibition of tumor progression. The results from this study provide new insights into the role of hypoxia in tumor progression and therapeutic strategies for cancer treatment.

Anti-proliferative effects of O-acyl-low-molecular-weight heparin derivatives on bovine pulmonary artery smooth muscle cells.

Heparin (HP) inhibits the growth of several cell types in vitro including bovine pulmonary artery (BPA) smooth muscle cells (SMCs). In initial studies we discovered that an O-hexanoylated low-molecular-weight (LMW) HP derivative having acyl groups with 6-carbon chain length was more potent inhibitor of BPA-SMCs than the starting HP. We prepared several O-acylated LMWHP derivatives having 4-, 6-, 8-, 10-, 12-, and 18- carbon acyl chain lengths to determine the optimal acyl chain length for maximum anti-proliferative properties of BPA-SMCs. The starting LMWHP was prepared from unfractionated HP by sodium periodate treatment followed by sodium borohydride reduction. The tri-n-butylammonium salt of this LMWHP was O-acylated with butanoic, hexanoic, octanoic, decanoic, dodecanoic, and stearyl anhydrides separately to give respective O-acylated LMWHP derivatives. Gradient polyacrylamide gel electrophoresis (PAGE) was used to examine the average molecular weights of those O-acylated LMWHP derivatives. NMR analysis indicated the presence of one O-acyl group per disaccharide residue. Measurement of the inhibition of BPA-SMCS as a function of O-acyl chain length shows two optima, at a carbon chain length of 6 (O-hexanoylated LMWHP) and at a carbon chain length 12-18 (O-dodecanoyl and O-stearyl LMWHPs). A solution competition SPR study was performed to test the ability of different O-acylated LMWHP derivatives to inhibit fibroblast growth factor (FGF) 1 and FGF2 binding to surface-immobilized heparin. All the LMWHP derivatives bound to FGF1 and FGF2 but each exhibited slightly different binding affinity.

Hypoxia does neither stimulate pulmonary artery endothelial cell proliferation in mice and rats with pulmonary hypertension and vascular remodeling nor in human pulmonary artery endothelial cells.

BACKGROUND: Hypoxia results in pulmonary hypertension and vascular remodeling due to induction of pulmonary artery cell proliferation. Besides pulmonary artery smooth muscle cells, pulmonary artery endothelial cells (PAECs) are also involved in the development of pulmonary hypertension, but the effect of hypoxia on PAEC proliferation has not been completely understood. METHODS: We investigated PAEC proliferation in mice and rats with hypoxia-induced pulmonary hypertension and vascular remodeling as well as in human PAECs under hypoxia. RESULTS AND CONCLUSION: We did not find significant PAEC proliferation in chronically hypoxic rats or mice. There was a slight decrease in proliferation in mice and rats with pulmonary hypertension and vascular remodeling. We also did not find significant human PAEC proliferation and cell cycle progression under different levels of oxygen (1, 2, 3, 5 and 10%) for one day, although the same conditions of hypoxia induced significant proliferation and cell cycle progression in pulmonary artery smooth muscle cells and pulmonary artery fibroblasts. Exposure to hypoxia for 7 days also did not increase PAEC proliferation. These results demonstrated that hypoxia alone is not a stimulus to PAEC proliferation in vivo and in vitro. The present study provides a novel role for PAECs in hypoxia-induced pulmonary hypertension and vascular remodeling.

Silencing of sodium-hydrogen exchanger 1 attenuates the proliferation, hypertrophy, and migration of pulmonary artery smooth muscle cells via E2F1.

We previously found that deficiency of the sodium-hydrogen exchanger 1 (NHE1) gene prevented hypoxia-induced pulmonary hypertension and vascular remodeling in mice, which were accompanied by a significantly reduced proliferation of pulmonary artery smooth muscle cells (PASMCs), and which decreased the medial-wall thickness of pulmonary arteries. That finding indicated the involvement of NHE1 in the proliferation and hypertrophy of PASMCs, but the underlying mechanism was not fully understood. To define the mechanism by which the inhibition of NHE1 decreases hypoxic pulmonary hypertension and vascular remodeling, we investigated the role of E2F1, a nuclear transcription factor, in silencing the NHE1 gene-induced inhibition of the proliferation, hypertrophy, and migration of human PASMCs. We found that: (1) silencing of NHE1 by short, interfering RNA (siRNA) significantly inhibited PASMC proliferation and cell cycle progression, decreased hypoxia-induced hypertrophy (in terms of cell size and protein/DNA ratio) and migration (in terms of the wound-healing and migration chamber assays); (2) hypoxia induced the expression of E2F1, which was reversed by NHE1 siRNA; and (3) the overexpression of E2F1 blocked the inhibitory effect of NHE1 siRNA on the proliferation, hypertrophy, and migration of PASMCs. The present study determined that silencing the NHE1 gene significantly inhibited the hypoxia-induced proliferation, hypertrophy, and migration of human PASMCs via repression of the nuclear transcription factor E2F1. This study revealed a novel mechanism underlying the regulation of hypoxic pulmonary hypertension and vascular remodeling via NHE1.

Thrombospondin-1, endothelium and systemic vascular tone.

Evaluation of: Bauer EM, Qin Y, Miller TW et al.: Thrombospondin-1 supports blood pressure by limiting eNOS activation and endothelial dependent vasorelaxation. Cardiovasc. Res. 88, 471-481 (2010). Several lines of evidence, both in vivo and ex vivo, suggest that thrombospondin-1 (TSP-1) is important in maintaining systemic vascular tone. Recently published papers demonstrate that TSP-1 can inhibit vascular smooth muscle relaxation by interfering with the interaction between nitric oxide (NO) and soluble guanylyl cyclase, providing a possible mechanism of action to explain this observation. While these in vitro experiments in vascular smooth muscle cells were provocative, it is not clear how such a large protein circulating in the plasma could cross the intact endothelial basal membrane and regulate NO/cGMP signaling in smooth muscle in vivo. This raised the question of whether TSP-1 could modulate NO/cGMP signaling through another mechanism. Herein, we evaluate a recently published paper by Bauer and colleagues that examined whether TSP-1 could exert vasoactive effects without directly accessing the vascular smooth muscle. In their studies they found that TSP-1 could inhibit the NO/cGMP signaling pathway through an alternate mechanism: inhibiting the activation of endothelial NO synthase (eNOS), and therefore NO production in endothelial cells. These findings, combined with previous results from these investigators, suggest that TSP-1 can blunt NO/cGMP signaling through two different mechanisms: inhibiting NO production in endothelial cells by preventing the agonist-induced influx of Ca(2+) required to activate endothelial NO synthase and blunting the ability of endothelial-derived NO to activate soluble guanylyl cyclase in vascular smooth muscle cells. The importance of these two pathways in supporting systemic and pulmonary vascular tone in health and disease is unclear.

Low molecular weight (LMW) heparin inhibits injury-induced femoral artery remodeling in mouse via upregulating CD44 expression.

OBJECTIVE: The mechanism of postangioplasty restenosis remains poorly understood. Low molecular weight (LMW) heparin has been shown to inhibit the proliferation of vascular smooth muscle cells (VSMCs), which is the principal characteristic of restenosis. Studies have shown that LMW heparin could bind to CD44. We hypothesized that LMW heparin might modulate CD44 expression thereby decreasing vascular remodeling. METHODS: Vascular remodeling was induced in CD44(+/+) and CD44(-/-) mice and treated with LMW heparin. The arteries were harvested for histologic assessment and determination of CD44 expression. Bone marrow transplantation was introduced to further explore the role and functional sites of CD44. Effects of LMW heparin on growth capacity, CD44 expression were further studied using the cultured mouse VSMCs. RESULTS: Transluminal injury induced remarkable remodeling in mouse femoral artery (sham wall thickness percentage [WT%]: 3.4 ± 1.2% vs injury WT%: 31.8 ± 4.7%; P < .001). LMW heparin reduced the remodeling significantly (WT%: 17.8 ± 3.5%, P < .005). CD44(-/-) mice demonstrated considerably thicker arterial wall remodeling (WT%: 46.2 ± 7.6%, P = .0035), and CD44-chimeric mice exhibited equal contributions of the local and circulating CD44 signal to the neointima formation. LMW heparin markedly upregulated CD44 expression in the injured femoral arteries. In vitro, LMW heparin decreased mouse VSMC growth capacity and upregulated its CD44 expression simultaneously in a dose-dependent and time-dependent manner, which could be partially blocked by CD44 inhibitor. CONCLUSIONS: LMW heparin inhibits injury-induced femoral artery remodeling, at least partially, by upregulating CD44 expression.

Effect of chemokine receptor CXCR4 on hypoxia-induced pulmonary hypertension and vascular remodeling in rats.

BACKGROUND: CXCR4 is the receptor for chemokine CXCL12 and reportedly plays an important role in systemic vascular repair and remodeling, but the role of CXCR4 in development of pulmonary hypertension and vascular remodeling has not been fully understood. METHODS: In this study we investigated the role of CXCR4 in the development of pulmonary hypertension and vascular remodeling by using a CXCR4 inhibitor AMD3100 and by electroporation of CXCR4 shRNA into bone marrow cells and then transplantation of the bone marrow cells into rats. RESULTS: We found that the CXCR4 inhibitor significantly decreased chronic hypoxia-induced pulmonary hypertension and vascular remodeling in rats and, most importantly, we found that the rats that were transplanted with the bone marrow cells electroporated with CXCR4 shRNA had significantly lower mean pulmonary pressure (mPAP), ratio of right ventricular weight to left ventricular plus septal weight (RV/(LV+S)) and wall thickness of pulmonary artery induced by chronic hypoxia as compared with control rats. CONCLUSIONS: The hypothesis that CXCR4 is critical in hypoxic pulmonary hypertension in rats has been demonstrated. The present study not only has shown an inhibitory effect caused by systemic inhibition of CXCR4 activity on pulmonary hypertension, but more importantly also has revealed that specific inhibition of the CXCR4 in bone marrow cells can reduce pulmonary hypertension and vascular remodeling via decreasing bone marrow derived cell recruitment to the lung in hypoxia. This study suggests a novel therapeutic approach for pulmonary hypertension by inhibiting bone marrow derived cell recruitment.

TLR4 through IFN-ß promotes low molecular mass hyaluronan-induced neutrophil apoptosis.

Intratracheal administration of low molecular mass (LMM) hyaluronan (200 kDa) results in greater neutrophil infiltration in the lungs of TLR4(-/-) mice compared with that in wild-type mice. In general, enhanced neutrophil infiltration in tissue is due to cell influx; however, neutrophil apoptosis also plays an important role. We have assessed the effects of TLR4 in the regulation of neutrophil apoptosis in response to administration of LMM hyaluronan. We found that apoptosis of inflammatory neutrophils is impaired in TLR4(-/-) mice, an effect that depends upon the IFN-ß-mediated TRAIL/TRAILR system. IFN-ß levels were decreased in LMM hyaluronan-treated TLR4-deficient neutrophils. The treatment of inflammatory neutrophils with IFN-ß enhanced the levels of TRAIL and TRAILR 2. LMM hyaluronan-induced inflammatory neutrophil apoptosis was substantially prevented by anti-TRAIL neutralizing mAb. We conclude that decreased IFN-ß levels decrease the activity of the TRAIL/TRAILR system in TLR4-deficient neutrophils, leading to impaired apoptosis of neutrophils and resulting in abnormal accumulation of neutrophils in the lungs of LMM hyaluronan-treated mice. Thus, TLR4 plays a novel homeostatic role in noninfectious lung inflammation by accelerating the elimination of inflammatory neutrophils.

Heparin inhibits pulmonary artery smooth muscle cell proliferation through guanine nucleotide exchange factor-H1/RhoA/Rho kinase/p27.

Ras homolog gene family member A (RhoA) through Rho kinase kinase (ROCK), one of its downstream effectors, regulates a wide range of cell physiological functions, including vascular smooth muscle cell (SMC) proliferation, by degrading cyclin-dependent kinase inhibitor, p27. Our previous studies found that heparin inhibition of pulmonary artery SMC (PASMC) proliferation and pulmonary hypertension was dependent on p27 up-regulation. To investigate whether ROCK, a regulator of p27, is involved in regulation of heparin inhibition of PASMC proliferation, we analyzed ROCK expression in the lungs from mice and from human PASMCs exposed to hypoxia, and investigated the effect of ROCK expression in vitro by RhoA cDNA transfection. We also investigated the effect of guanine nucleotide exchange factor (GEF)-H1, an upstream regulator of RhoA, on heparin inhibition of PASMC proliferation by GEF-H1 cDNA transfection. We found that: (1) hypoxia increased ROCK expression in mice and PASMCs; (2) overexpression of RhoA diminished the inhibitory effect of heparin on PASMC proliferation and down-regulated p27 expression; and (3) overexpression of GEF-H1 negated heparin inhibition of PASMC proliferation, which was accompanied by increased GTP-RhoA and decreased p27. This study demonstrates that the RhoA/ROCK pathway plays an important role in heparin inhibition on PASMC proliferation, and reveals that heparin inhibits PASMC proliferation through GEF-H1/RhoA/ROCK/p27 signaling pathway, by down-regulating GEF-H1, RhoA, and ROCK, and then up-regulating p27.

Estimated incidence of acute pulmonary embolism in a Korean hospital.

Patients with acute pulmonary embolism (PE) were identified retrospectively from patients hospitalized during a 2-year period from 2005 to 2007. Among adult patients (≥20 years), the incidence of established acute PE was 88 (0.17%) of 50 882 in Dongsan Hospital. The incidence of acute PE at Dongsan Hospital was 26% lower than that at Henry Ford Hospital (P < .01). Among patients more than 50 years of age, PE was more frequent in women (0.32%; 95% CI, 0.24-0.4) than in men (0.15%; 95% CI, 0.1-0.21; P < .01). Among all patients with PE older than 20 years of age, 68 (0.21%) of 31 869 (95% CI, 0.17-0.26) were from the medical service and 18 (0.08%) of 23 139 (95% CI, 0.04-0.11; P < .01) were from the surgical service. The estimated incidence of PE in a university teaching hospital in Korea was 0.17%, it was about two thirds of that in North America.

JNK activation is responsible for mucus overproduction in smoke inhalation injury.

BACKGROUND: Increased mucus secretion is one of the important characteristics of the response to smoke inhalation injuries. We hypothesized that gel-forming mucins may contribute to the increased mucus production in a smoke inhalation injury. We investigated the role of c-Jun N-terminal kinase (JNK) in modulating smoke-induced mucus secretion. METHODS: We intubated mice and exposed them to smoke from burning cotton for 15 min. Their lungs were then isolated 4 and 24 h after inhalation injury. Three groups of mice were subjected to the smoke inhalation injury: (1) wild-type (WT) mice, (2) mice lacking JNK1 (JNK1-/- mice), and (3) WT mice administered a JNK inhibitor. The JNK inhibitor (SP-600125) was injected into the mice 1 h after injury. RESULTS: Smoke exposure caused an increase in the production of mucus in the airway epithelium of the mice along with an increase in MUC5AC gene and protein expression, while the expression of MUC5B was not increased compared with control. We found increased MUC5AC protein expression in the airway epithelium of the WT mice groups both 4 and 24 h after smoke inhalation injury. However, overproduction of mucus and increased MUC5AC protein expression induced by smoke inhalation was suppressed in the JNK inhibitor-treated mice and the JNK1 knockout mice. Smoke exposure did not alter the expression of MUC1 and MUC4 proteins in all 3 groups compared with control. CONCLUSION: An increase in epithelial MUC5AC protein expression is associated with the overproduction of mucus in smoke inhalation injury, and that its expression is related on JNK1 signaling.

High MW hyaluronan inhibits smoke inhalation-induced lung injury and improves survival.

BACKGROUND AND OBJECTIVE: High MW hyaluronan (HMW HA) as opposed to low MW hyaluronan (LMW HA) has been shown to have anti-inflammatory and anti-apoptotic effects. We hypothesized that treatment with HMW HA would block smoke inhalation lung injury by inhibiting smoke-induced lung inflammation and airway epithelial cell apoptosis. METHODS: Anesthetized, intubated male rats were randomly allocated to either control or smoke inhalation injury groups. Rats were treated with 3-mL subcutaneous normal saline solution (sham) or LMW HA (35 kDa) or HMW HA (1600 kDa) 18 h before exposure to 15 min of cotton smoke (n = 5 each). Rats were also treated post smoke inhalation with 1600 kDa HA by intra-peritoneal injection (3 mL) or intra-tracheal nebulization (200 µL). Lung neutrophil infiltration, airway apoptosis, airway mucous plugging and lung injury were assessed 4 h after smoke inhalation injury. RESULTS: Rats pretreated with 1600 kDa HA had significantly less smoke-induced neutrophil infiltration, lung oedema, airway apoptosis and mucous plugging. Pretreatment with 35 kDa HA, in contrast, increased smoke-induced neutrophil infiltration and lung injury score. Intra-tracheal administration of a single dose 1600 kDa HA, but not intra-peritoneal injection, significantly improved survival post smoke inhalation. CONCLUSIONS: High MW hyaluronan (1600 kDa) may prove to be a beneficial therapy for smoke inhalation through inhibition of smoke-induced inflammation, lung oedema, airway epithelial cell apoptosis and airway mucous plugging.

Thrombospondin-1 null mice are resistant to hypoxia-induced pulmonary hypertension.

BACKGROUND AND OBJECTIVE: Chronic hypoxia induces pulmonary hypertension in mice. Smooth muscle cell hyperplasia and medial thickening characterize the vasculature of these animals. Thrombospondin-1 null (TSP-1(-/-)) mice spontaneously develop pulmonary smooth muscle cell hyperplasia and medial thickening. In addition, TSP-1 produced by the pulmonary endothelium inhibits pulmonary artery smooth muscle cell growth. Based on these observations we sought to describe the pulmonary vascular changes in TSP-1(-/-) mice exposed to chronic hypoxia. METHODS: We exposed TSP-1(-/-) and wild type (WT) mice to a fraction of inspired oxygen (FiO2) of 0.1 for up to six weeks. Pulmonary vascular remodeling was evaluated using tissue morphometrics. Additionally, right ventricle systolic pressures (RVSP) and right ventricular hypertrophy by right ventricle/left ventricle + septum ratios (RV/LV+S) were measured to evaluate pulmonary hypertensive changes. Finally, acute pulmonary vasoconstriction response in both TSP-1(-/-) and WT mice was evaluated by acute hypoxia and U-46619 (a prostaglandin F2 analog) response. RESULTS: In hypoxia, TSP-1(-/-) mice had significantly lower RVSP, RV/LV+S ratios and less pulmonary vascular remodeling when compared to WT mice. TSP-1(-/-) mice also had significantly lower RVSP in response to acute pulmonary vasoconstriction challenges than their WT counterparts. CONCLUSION: TSP-1(-/-) mice had diminished pulmonary vasoconstriction response and were less responsive to hypoxia-induced pulmonary hypertension than their wild type counterparts. This observation suggests that TSP-1 could play an active role in the pathogenesis of pulmonary hypertension associated with hypoxia.

Effect of carboxyl-reduced heparin on the growth inhibition of bovine pulmonary artery smooth muscle cells.

Heparin (HP) inhibits the proliferation of bovine pulmonary artery smooth muscle cells (BPASMC's), among other cell types in vitro. In order to develop a potential therapeutic agent to reverse vascular remodeling, we are involved in deciphering the relationship between the native HP structure and its antiproliferative potency. We have previously reported the influence of the molecular size and the effects of various O-sulfo and N-acetyl groups of HP on growth-inhibitory activity. In this study, to understand the influence of carboxyl groups in the HP structure required for endogenous activity, a chemically modified derivative of native HP was prepared by converting the carboxyl groups of hexuronic acid residues in HP to primary hydroxyl groups. This modification procedure involves the treatment of HP with N-(3-dimethylaminopropyl)-N-ethylcarbodiimide followed by reduction with NaBH(4) to yield carboxyl-reduced heparin (CR-HP). When compared to the antiproliferative potency of native HP on cultured BPASMC's at three dose levels (1, 10, and 100 microg/mL), the CR-HP showed significantly less potency at all the doses. These results suggest that hexuronic acid residues in both major and variable sequences in HP are essential for the antiproliferative properties of native HP.

Gadolinium-enhanced magnetic resonance angiography for pulmonary embolism: a multicenter prospective study (PIOPED III).

BACKGROUND: The accuracy of gadolinium-enhanced magnetic resonance pulmonary angiography and magnetic resonance venography for diagnosing pulmonary embolism has not been determined conclusively. OBJECTIVE: To investigate performance characteristics of magnetic resonance angiography, with or without magnetic resonance venography, for diagnosing pulmonary embolism. DESIGN: Prospective, multicenter study from 10 April 2006 to 30 September 2008. SETTING: 7 hospitals and their emergency services. PATIENTS: 371 adults with diagnosed or excluded pulmonary embolism. MEASUREMENTS: Sensitivity, specificity, and likelihood ratios were measured by comparing independently read magnetic resonance imaging with the reference standard for diagnosing pulmonary embolism. Reference standard diagnosis or exclusion was made by using various tests, including computed tomographic angiography and venography, ventilation-perfusion lung scan, venous ultrasonography, d-dimer assay, and clinical assessment. RESULTS: Magnetic resonance angiography, averaged across centers, was technically inadequate in 25% of patients (92 of 371). The proportion of technically inadequate images ranged from 11% to 52% at various centers. Including patients with technically inadequate images, magnetic resonance angiography identified 57% (59 of 104) with pulmonary embolism. Technically adequate magnetic resonance angiography had a sensitivity of 78% and a specificity of 99%. Technically adequate magnetic resonance angiography and venography had a sensitivity of 92% and a specificity of 96%, but 52% of patients (194 of 370) had technically inadequate results. LIMITATION: A high proportion of patients with suspected embolism was not eligible or declined to participate. CONCLUSION: Magnetic resonance pulmonary angiography should be considered only at centers that routinely perform it well and only for patients for whom standard tests are contraindicated. Magnetic resonance pulmonary angiography and magnetic resonance venography combined have a higher sensitivity than magnetic resonance pulmonary angiography alone in patients with technically adequate images, but it is more difficult to obtain technically adequate images with the 2 procedures.