Nitric oxide mediates acute lung injury caused by fat embolism in isolated rat’s lungs. ACTA ACUST UNITED AC. 2008;64:462-469. [PMID: 18301216 DOI: 10.1097/ta.0b013e318058aa2e]

Clinical Characteristics of Transarterial Chemoembolization in Treatment of Primary Hepatocellular Carcinoma Complicated With Respiratory Distress Syndrome

Objective:

The present study aims to analyze the clinical characteristics and etiology of transarterial chemoembolization (TACE) in the treatment of hepatocellular carcinoma (HCC) complicated with acute respiratory distress syndrome (ARDS), in order to improve the early diagnosis rate and cure rate.

Methods:

A total of 816 patients with primary HCC received 2,200 TACE treatments from January 2014 to May 2018. Among these patients, 6 patients developed ARDS after TACE. The clinical data, lesion characteristics, laboratory tests, treatment process and prognosis of 6 patients were retrospectively analyzed.

Results:

The longest lesion diameter ranged within 5.0-10.2 cm (mean: 6.6 cm) in the 6 patients with primary HCC. Among these patients, 4 patients had lesions mainly located in the left lateral lobe of the liver, while 5 patients had no hepatic arteriovenous fistula detected before TACE. Nedaplatin, epirubicin and iodinated oil suspension chemoembolization were used in all 6 patients during TACE, and all of them experienced ARDS symptoms within 24-48 hours after TACE. However, no clear pathogenic bacteria were incubated in the sputum culture after the onset of the disease. Diffused exudative changes of both lungs were found in the chest X-ray, and the oxygenation index (PaO₂/FiO₂) was within 100-300 mmHg. The symptoms of 6 patients improved after 3-6 days of hormone therapy.

Conclusion:

In this study, we found that although the incidence of ARDS after TACE was low in the treatment for HCC, the symptoms after onset were serious, and the early hormone therapy may be beneficial to improve the prognosis and reduce mortality. Further research with larger samples is still needed to confirm the pathogenesis of ARDS after TACE in the treatment for HCC.

VEGF mediates fat embolism-induced acute lung injury via VEGF receptor 2 and the MAPK cascade

Fat embolism (FE) is a lethal medical emergency often caused by fracture of long bones and amputation of limbs. Vascular endothelial growth factor (VEGF) promotes angiogenesis and increases vascular permeability. We tested the hypothesis that VEGF plays a critical role in FE-induced acute respiratory distress syndrome (ARDS) and acute lung injury (ALI). Fat tissues were collected from male Sprague-Dawley rats, and animal oil was extracted and mixed with water to form fatty micelles. The micelles were then injected into the tail vein to produce FE and ALI in rats. Lung weight gain was measured as the index of pulmonary edema. The expression of pulmonary VEGF was evaluated by real-time PCR and western blot analysis. Inducible nitric oxide synthase (iNOS) and phosphorylation of mitogen-activated protein kinase (MAPK) were determined by western blot analyses. Interleukin-1β (IL-1β) was quantified by ELISAs. Hematoxylin and eosin staining was used to evaluate the pathological damage of ALI. In this study, we found that animal oil-induced FE significantly increased pulmonary VEGF expression and MAPK phosphorylation. We also evaluated the inflammatory response after FE and found that iNOS and IL-1β significantly increased after FE. Systemic administration of SU-1498, an antagonist of VEGF receptor 2 (VEGFR-2), significantly attenuated the FE-induced inflammatory response and histological damage. This study suggested that VEGF is involved in FE-induced ARDS via the VEGFR-2 and MAPK cascades, which induce IL-1β release and iNOS upregulation. Blockade of could be used to treat FE-induced pulmonary damage.

Pulmonary embolism after arterial chemoembolization for hepatocellular carcinoma: An autopsy case report

We report an extremely rare case of pulmonary lipiodol embolism with acute respiratory distress syndrome (ARDS) after transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). A 77-year-old man who was diagnosed with a huge HCC was admitted for TACE. Immediately after the procedure, this patient experienced severe dyspnea. We suspected that his symptoms were associated with a pulmonary lipiodol embolism after TACE, and we began intensive treatment. However, his condition did not improve, and he died on the following day. A subsequent autopsy revealed that the cause of death was ARDS due to pulmonary lipiodol embolism. No cases have been previously reported for which an autopsy was performed to explain the most probable mechanism of pulmonary lipiodol embolism; thus, ours is the first report for such a rare case.

Pulmonary fat embolism and related effects during femoral intramedullary surgery: An experimental study in dogs

The aim of the present study was to develop an animal model of pulmonary fat embolism (PFE) caused by femoral intramedullary procedures, and to investigate the initial changes in the hemodynamics, cytokines and risk factors of PFE. Sixteen dogs were randomly divided into two groups: Group A (intramedullary reaming and bone cement injection, n=8) and Group B (surgical approach without opening the medullary cavity, n=8). The hemodynamics, arterial blood gases and relevant cytokines were evaluated, and the lungs were examined using Oil Red O staining. In the animals of Group A, the heart rate, central venous pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure and extravascular lung water (EVLW) were increased compared with the baseline levels, while the mean arterial pressure was decreased immediately following the reaming and bone cement infusion (P<0.05). Furthermore, there was a significant reduction in the pH and the arterial oxygen tension (PaO₂), and a significant increase in the arterial carbon dioxide tension (PaCO₂; P<0.05 for all) following the bilateral intramedullary surgery. The EVLW was correlated with the PaO₂ (P<0.001) and PaCO₂ (P=0.046). Following surgery, there was a significant increase in tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 levels in Group A (P<0.05). However, there were no significant changes in these parameters in Group B. The parameters tested, with the exception of pH, were significantly different in Group A compared with those in Group B (P<0.05) following the bilateral intramedullary surgery. Oil Red O staining was positive for all animals in Group A and negative for those in Group B. Femoral intramedullary surgery may induce PFE and subsequently affect hemodynamics and arterial blood gases. EVLW was correlated with the PaO₂ (P<0.001) and the PaCO₂ (P=0.046). These results demonstrated that EVLW and cytokines may serve as predictors of the development of fat embolism syndrome (FES).

Ursolic acid attenuates lipopolysaccharide-induced acute lung injury in a mouse model

AIM

To assess whether ursolic acid (UA) can attenuate lipopolysachharide (LPS)-induced acute lung injury and improve the survival time in a mouse model.

MATERIALS & METHODS

The mice were challenged with LPS and survival time was monitored from 0-96 h after LPS treatment. TNF-α, IL-6, IL-1β, HMGB1, nitric oxide (NO) and IL-10 concentration in serum were measured by ELISA. Myeloperoxidase activity, malondialdehyde, lung wet:dry weight ratio and lung permeability in lung tissues were detected. NF-κB, HMGB1 and inducible NO synthase in the lungs were detected by western blot.

RESULTS

UA markedly rescued lethality, improved survival time and lung pathological changes, inhibited TNF-α, IL-6, IL-1β, HMGB1 and NO, and increased IL-10 expression. In addition, UA can also decrease myeloperoxidase, malondialdehyde, lung wet:dry weight ratio and lung permeability. UA attenuated NF-κB, HMGB1 and inducible NO synthase protein expression in the lungs.

CONCLUSION

The results suggest that UA is capable of improving survival time and LPS-induced acute lung injury. UA has a potentially therapeutic role in septic shock.

Acute lung injury and acute respiratory distress syndrome: experimental and clinical investigations

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) can be associated with various disorders. Recent investigation has involved clinical studies in collaboration with clinical investigators and pathologists on the pathogenetic mechanisms of ALI or ARDS caused by various disorders. This literature review includes a brief historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the long-term experimental studies and clinical investigations from our laboratory, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

Acute respiratory distress syndrome and lung injury: Pathogenetic mechanism and therapeutic implication

To review possible mechanisms and therapeutics for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). ALI/ARDS causes high mortality. The risk factors include head injury, intracranial disorders, sepsis, infections and others. Investigations have indicated the detrimental role of nitric oxide (NO) through the inducible NO synthase (iNOS). The possible therapeutic regimen includes extracorporeal membrane oxygenation, prone position, fluid and hemodynamic management and permissive hypercapnic acidosis etc. Other pharmacological treatments are anti-inflammatory and/or antimicrobial agents, inhalation of NO, glucocorticoids, surfactant therapy and agents facilitating lung water resolution and ion transports. β-adrenergic agonists are able to accelerate lung fluid and ion removal and to stimulate surfactant secretion. In conscious rats, regular exercise training alleviates the endotoxin-induced ALI. Propofol and N-acetylcysteine exert protective effect on the ALI induced by endotoxin. Insulin possesses anti-inflammatory effect. Pentobarbital is capable of reducing the endotoxin-induced ALI. In addition, nicotinamide or niacinamide abrogates the ALI caused by ischemia/reperfusion or endotoxemia. This review includes historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

A comparative study of the mortality rate of rats receiving a half lethal dose of fat intravenously: under general anaesthesia versus under spinal anaesthesia

BACKGROUND

There is no data that demonstrates what anaesthesia is suitable for patients who have a high risk of fat embolism syndrome (FES). We investigated the mortality rates of rats that received a half lethal dose (LD(50)) of fat by intravenous injection after induction of general or spinal anaesthesia.

METHODS

An LD(50) of fat for rats was determined by using a toxicological method. Three hundred and seventy five rats were randomly assigned to receive general anaesthesia (group GA, n=125), or spinal block (group SA, n=125), or no anaesthesia (group C, n=125). The rats were injected with the LD(50) of fat at 20 min after anaesthesia induction. The mortality rates were recorded at 2, 8, 12, and 24h after fat injection.

RESULTS

The LD(50) of fat was 0.706 ml/kg and its 95% CI was 0.622 ml/kg-0.801 ml/kg. The mortality rate was lower in the group GA than in the group SA (p<0.01), whilst there was no statistical difference between the group SA and the group C (p=0.442).

CONCLUSION

It is feasible to assess the efficacy of various treatments for FES by comparing the mortality rates of animals after injection of an LD(50) of fat. The mortality rate of rats was lower when FES was induced under general anaesthesia than under spinal anaesthesia which implies that general anaesthesia is superior to spinal anaesthesia for patients who have a high risk of FES.

Niacinamide mitigated the acute lung injury induced by phorbol myristate acetate in isolated rat's lungs

BACKGROUND

Phorbol myristate acetate (PMA) is a strong neutrophil activator and has been used to induce acute lung injury (ALI). Niacinamide (NAC) is a compound of B complex. It exerts protective effects on the ALI caused by various challenges. The purpose was to evaluate the protective effects of niacinamide (NAC) on the PMA-induced ALI and associated changes.

METHODS

The rat's lungs were isolated in situ and perfused with constant flow. A total of 60 isolated lungs were randomized into 6 groups to received Vehicle (DMSO 100 μg/g), PMA 4 μg/g (lung weight), cotreated with NAC 0, 100, 200 and 400 mg/g (lung weight). There were 10 isolated lungs in each group. We measured the lung weight and parameters related to ALI. The pulmonary arterial pressure and capillary filtration coefficient (Kfc) were determined in isolated lungs. ATP (adenotriphosphate) and PARP [poly(adenosine diphophate-ribose) polymerase] contents in lung tissues were detected. Real-time PCR was employed to display the expression of inducible and endothelial NO synthases (iNOS and eNOS). The neutrophil-derived mediators in lung perfusate were determined.

RESULTS

PMA caused increases in lung weight parameters. This agent produced pulmonary hypertension and increased microvascular permeability. It resulted in decrease in ATP and increase in PARP. The expression of iNOS and eNOS was upregulated following PMA. PMA increased the neutrophil-derived mediators. Pathological examination revealed lung edema and hemorrhage with inflammatory cell infiltration. Immunohistochemical stain disclosed the presence of iNOS-positive cells in macrophages and endothelial cells. These pathophysiological and biochemical changes were diminished by NAC treatment. The NAC effects were dose-dependent.

CONCLUSIONS

Our results suggest that neutrophil activation and release of neutrophil-derived mediators by PMA cause ALI and associated changes. NO production through the iNOS-producing cells plays a detrimental role in the PMA-induced lung injury. ATP is beneficial, while PARP plays a deteriorative effect on the PMA-induced ALI. NAC exerts protective effects on the inflammatory cascade leading to pulmonary injury. This B complex compound may be applied for clinical usage and therapeutic regimen.

Effects of phorbol myristate acetate and sivelestat on the lung injury caused by fat embolism in isolated lungs

Background

Fat embolism syndrome (FES) associated with acute lung injury (ALI) is a clinical condition following long bone fracture. We have reported 14 victims due to ALI with FES. Our laboratory has developed an animal model that produced fat emboli (FE). The major purpose of this study was to test whether neutrophil activation with phorbol myristate acetate (PMA) and inhibition with sivelestat (SVT) exert protection on the lung.

Methods

The lungs of Sprague-Dawley rats were isolated and perfused. FE was produced by addition of corn oil micelles into the lung perfusate. PMA and SVT were given simultaneously with FE. Parameters such as lung weight/body weight ratio, LW gain, exhaled nitric oxide (NO), protein concentration in bronchoalveolar lavage relating to ALI were measured. The neutrophil elastase (NE), myeloperoxidase, malondialdehyde and phopholipase A₂ activity were determined. We also measured the nitrate/nitrite, methyl guanidine (MG), and cytokines. Pulmonary arterial pressure and microvascular permeability were assessed. Lung pathology was examined and scored. The inducible and endothelial NO synthase (iNOS and eNOS) were detected.

Results

FE caused ALI and increased biochemical factors. The challenge also resulted in pulmonary hypertension and increased microvascular permeability. The NE appeared to be the first to reach its peak at 1 hr, followed by other factors. Coadministration with PMA exacerbated the FE-induced changes, while SVT attenuated the effects of FE.

Conclusions

The FE-induced lung changes were enhanced by PMA, while SVT had the opposite effect. Sivelestat, a neutrophil inhibitor may be a therapeutic choice for patients with acute respiratory distress syndrome (ARDS) following fat embolism.

Protective effect of sesamol on the pulmonary inflammatory response and lung injury in endotoxemic rats

We investigated the effect of sesamol on systemic lipopolysaccharide (LPS)-induced lung inflammation in rats. Sesamol decreased lung edema and injury, significantly decreased LPS-induced cell counts, protein concentration, tumor necrosis factor (TNF)-alpha, and nitrite levels in bronchoalveolar lavage fluid, and decreased the TNF-alpha, nitrite, and inducible nitric oxide synthase protein expression in lung tissue. Further, sesamol significantly inhibited LPS-induced TNF-alpha, nitrite, inducible nitric oxide synthase expression, and nuclear factor-kappaB activation levels in primary alveolar macrophages. We hypothesize that sesamol attenuates systemic LPS-induced lung inflammation by inhibiting the alveolar macrophage inflammatory response in rats.

Beneficial microvascular and anti-inflammatory effects of pravastatin during sepsis involve nitric oxide synthase III

BACKGROUND

Sepsis induces microvascular inflammation and production of the vasodilator nitric oxide (NO) via endothelial and inducible nitric oxide synthase (eNOS or NOS III and iNOS or NOS II). Statins are cholesterol-lowering drugs; however, they also attenuate inflammation. This study aimed to determine whether pravastatin protected against sepsis-induced hypotension, loss of vascular tone, and microvascular inflammation via NOS pathways.

METHODS

Male Wistar rats (n=18) were anaesthetized and the mesentery prepared for fluorescent intravital microscopy. Animals received either lipopolysaccharide (LPS; n=6); LPS+pravastatin (18 and 3 h before LPS; n=6), or saline as a control, for 4 h.

RESULTS

Mean arterial pressure decreased in LPS-treated animals (P<0.05), but not in those also receiving pravastatin. Acetylcholine-induced relaxation of venules was abolished by LPS but improved by pravastatin. Pravastatin also reduced the increase in nitrite concentration and macromolecular leak from venules induced by LPS (P<0.05). The increased leucocyte adhesion seen in LPS-treated rats was also reduced in those also treated with pravastatin. Immunohistochemical analysis showed that pravastatin increased endothelial cell expression of NOS III during sepsis, but had no effect on LPS-induced up-regulation of NOS II.

CONCLUSIONS

Pravastatin improved NOS III-mediated vessel relaxation and exerted anti-inflammatory effects within the microcirculation after LPS administration in rats. Pravastatin therefore appears to have beneficial effects during sepsis, as a result of increased microvascular expression and function of NOS III.

Acute respiratory distress syndrome after transcatheter arterial chemoembolization of hepatocellular carcinomas

BACKGROUND

Acute respiratory distress syndrome (ARDS) associated with pulmonary lipiodol embolism is a rare complication of transcatheter arterial chemoembolization (TACE). We performed a survey of ARDS associated with pulmonary lipiodol embolism after TACE.

METHODS

A retrospective analysis of the cases of all patients with hepatic tumors who received transcatheter arterial embolization or TACE between January 2006 and December 2006 was performed. The diagnosis of pulmonary lipiodol embolism was confirmed by chest computed tomography (CT).

RESULTS

The diagnosis of ARDS associated with pulmonary lipiodol embolism was confirmed in 4 patients. All had large (> or =5 cm) and hypervascular tumors. There was no evidence of hepatocellular carcinoma arteriovenous shunting in any of our patients as determined by angiography and multidetector CT. The volumes of lipiodol infused in the 4 patients were 50, 20, 30, and 20 mL. Only 2 patients received injections of carcinostatic agents. The onset of respiratory symptoms occurred between 1 hour and 4 days after TACE. Respiratory symptoms consisted of dyspnea and tachypnea. Chest CT scans revealed linear high-density shadows, suggestive of lipiodol retention in both lungs of all patients.

CONCLUSION

Pulmonary lipiodol embolism after TACE can occur within a short time frame. Whether or not there is intrahepatic arteriovenous shunting detected by multidetector CT and angiography, clinicians should avoid high doses of iodized oil and carcinostatic agents. We suggest that CT should be used for the diagnosis of pulmonary lipiodol embolism.

Fat embolism

Fat embolism refers to the presence of fat droplets within the peripheral and lung microcirculation with or without clinical sequelae. The pathologic consequences of fat embolism are well recognized. Fat embolism is most often associated with trauma and orthopedic injuries. Fat embolism syndrome (FES) is a serious manifestation of fat embolism that involves a cascade of clinical signs such as petechial rash, deteriorating mental status, and progressive respiratory insufficiency, usually occurring within 24 hours of injury. This article reviews the definition, epidemiology, etiology, pathophysiology, clinical presentation, diagnosis, management, and prognosis of FES.

Interleukin-6 as an early marker for fat embolism

BACKGROUND

Fat Embolism is a complication of long bone fractures, intramedullary fixation and joint arthroplasty. It may progress to fat embolism syndrome, which is rare but involves significant morbidity and can occasionally be fatal. Fat Embolism can be detected at the time of embolization by transoesophageal echocardiography or atrial blood sampling. Later, a combination of clinical signs and symptoms will point towards fat embolism but there is no specific test to confirm the diagnosis. We investigated serum Interleukin-6 (IL-6) as a possible early marker for fat embolism.

METHODS

An animal study was conducted to simulate a hip replacement in 31 adult male Sprague Dawley rats. The procedure was performed under general anesthesia and the animals divided into 3 groups: control, uncemented and cemented. Following surgery and recovery from anaesthesia, the rats allowed to freely mobilize in their cages. Blood was taken before surgery and at 6 hours, 12 hours and 24 hours to measure serum IL-6 levels. The rats were euthanized at 24 hours and lungs removed and stained for fat. The amount of fat seen was then correlated with serum IL-6 levels.

RESULTS

No rats in the control group had fat emboli. Numerous fat emboli were seen in both the uncemented and cemented implant groups. The interleukin levels were raised in all groups reaching a peak at 12 hours after surgery reaching 100 pg/ml in the control group and around 250 pg/ml in the uncemented and cemented implant groups. The IL-6 levels in the control group were significantly lower than any of the implant groups at 12 and 24 hours. At these time points, the serum IL-6 correlated with the amount of fat seen on lung histology.

CONCLUSION

Serum IL-6 is a possible early marker of fat embolism.