Soon Eun Park

Tristetraprolin regulates expression of VEGF and tumorigenesis in human colon cancer

Tristetraprolin (TTP) is an AU‐rich element‐binding protein that regulates mRNA stability. Here, we report that TTP suppress the growth of human colon cancer cells both in vivo and in vitro by regulating of the expression of vascular endothelial growth factor (VEGF). TTP protein expression in human colonic tissues was markedly decreased in colonic adenocarcinoma compared with in normal mucosa and adenoma. VEGF expression was higher in colonic adenocarcinoma than in normal mucosa and adenoma. Specific inhibition of TTP expression by RNA‐interference increased the expression of VEGF in cultured human colon cancer cells, and TTP overexpression markedly decreased it. In addition, elevated expression of TTP decreased the expression level of luciferase linked to a 3′ terminal AU‐rich element (ARE) of VEGF mRNA. Colo320/TTP cells overexpressing TTP grew slowly in vitro and became tumors small in size when xenografted s.c into nude mice. These findings demonstrate that TTP acts as a negative regulator of VEGF gene expression in colon cancer cells, suggesting that it can be used as novel therapeutic agent to treat colon cancer.

Reactive oxygen species-dependent EndoG release mediates cisplatin-induced caspase-independent apoptosis in human head and neck squamous carcinoma cells

Cisplatin is a chemotherapeutic agent that is widely used to treat cancers such as head and neck squamous cell carcinoma (HNSCC). Previously, we have reported that cisplatin induced an early caspase‐dependent apoptosis (8 hr) in a HNSCC cell, HN4. In this study, we examined a late caspase‐independent apoptosis as well as an early caspase‐dependent apoptosis in cisplatin‐treated HN4 cells. While z‐VAD‐fmk, a pan‐caspase inhibitor, blocked the caspase activities and protected cells from the early apoptosis, it did not provide protection against delayed apoptosis occurring after extended exposure (16 hr) to cisplatin, suggesting that the delayed apoptotic response in the presence of z‐VAD‐fmk was caspase‐independent. Cisplatin treatment induced reactive oxygen species (ROS) generation, loss of the mitochondrial membrane potential (MMP) and nuclear translocation of endonuclease G (EndoG). Small interfering RNA mediated‐knockdown of EndoG significantly protected cells from the delayed apoptosis induced by cisplatin in the presence of z‐VAD‐fmk. Overexpression of Bcl‐2 in HN4 cells prevented loss of MMP, nuclear translocation of EndoG and protected cells from the delayed apoptosis induced by cisplatin in the presence of z‐VAD‐fmk. Pretreatment with N‐acetyl‐L‐cysteine (NAC), a ROS scavenger, prevented both ROS generation, loss of the MMP and nuclear translocation of EndoG. Together, our data indicate that cisplatin treatment induced ROS‐mediated loss of the MMP, and, then, the nuclear translocation of EndoG, which played a crucial role in caspase‐independent apoptosis of HN4 cells in the presence of z‐VAD‐fmk. This is the first report about the involvement of EndoG in cisplatin‐induced caspase‐independent apoptosis of cells.

Inhaled nitric oxide for the brain dead donor with neurogenic pulmonary edema during anesthesia for organ donation: a case report

Neurogenic pulmonary edema (NPE) in brain dead organ donors occurring after an acute central nervous system insult threatens organ preservation of potential organ donors and the outcome of organ donation. Hence the active and immediate management of NPE is critical. In this case, a 50-year-old male was admitted to the intensive care unit (ICU) for organ donation. He was hypoxic due to NPE induced by spontaneous intracerebral hemorrhage and intraventricular hemorrhage. Protective ventilatory management, intermittent recruitment maneuvers, and supportive treatment were maintained in the ICU and the operating room (OR). Despite this management, the hypoxemia worsened after the OR admission. So inhaled nitric oxide (NO) therapy was performed during the operation, and the hypoxic phenomena showed remarkable improvement. The organ retrieval was successfully completed. Therefore, NO inhalation can be helpful in the improvement of hypoxemia caused by NPE in brain dead organ donors during anesthesia for the organ donation.

Postoperative negative pressure pulmonary edema following repetitive laryngospasm even after reversal of neuromuscular blockade by sugammadex: a case report

Laryngospasm, an occlusion of the glottis, can occur at any time during anesthesia, and is associated with serious perioperative complications such as hypoxia, hypercabia, aspiration, bronchospasm, arrhythmia, prolonged recovery, cardiac collapse, and eventually catastrophic death. Importantly, postoperative negative pressure pulmonary edema (NPPE) is a rare, but well described life-threatening complication related to acute and chronic upper airway obstruction. Sugammadex well known for affirmatively reducing the postoperative pulmonary complications associated with residual neuromuscular blockade may have an indirect role in triggering the negative intrathoracic pressure by raising a rapid and efficacious respiratory muscle strength in acute upper airway obstruction. Herein, we report a case of postoperative NPPE following repetitive laryngospasm even after reversal of rocuronium-induced neuromuscular blockade using sugammadex.

Change of QT variability index during general anesthesia

Background The QT variability index (QTVI)–a non-invasive measure of beat-to-beat QT interval (QTI) fluctuations–is related to myocardial repolarization lability. The QTVI represents the relationship between QTI and the RR interval. Elevated QTVI is associated with an increased risk of malignant ventricular arrhythmias and sudden death. We investigated the influence of general anesthesia and tourniquets on the QTVI. Methods We studied fifty patients who received total knee replacement arthroplasty under sevoflurane anesthesia. We measured QTI, corrected QTI (QTc), T-wave peak-to-end interval (TPE), QTVI, and heart rate variability. All variables were calculated at baseline (B), 30 min after general anesthesia (A), 30 min (TQ1) and 60 min (TQ2) after tourniquet inflation, and at tourniquet deflation (TQR). Results Prolongation of QTI was detected at all times, and QTc was significantly prolonged TQR. TPE was unchanged during general anesthesia. The QTVI was significantly decreased and more negative during anesthesia and tourniquet inflation. After deflation of the tourniquet, the QTVI was restored to preanesthetic values. Low frequency (LF) was significantly decreased during general anesthesia, but high frequency (HF) was somewhat maintained, except at TQ2. The LF/HF ratio was significantly decreased at A and TQ2. Conclusions Sevoflurane based general anesthesia induced repolarization stability and, more negativity of the QTVI, in patients undergoing total knee replacement arthroplasty.

Involvement of Protein Kinase C-δ in Vascular Permeability in Acute Lung Injury

Pulmonary edema is a major cause of mortality due to acute lung injury (ALI). The involvement of protein kinase C-δ (PKC-δ) in ALI has been a controversial topic. Here we investigated PKC-δ function in ALI using PKC-δ knockout (KO) mice and PKC inhibitors. Our results indicated that although the ability to produce proinflammatory mediators in response to LPS injury in PKC-δ KO mice was similar to that of control mice, they showed enhanced recruitment of neutrophils to the lung and more severe pulmonary edema. PKC-δ inhibition promoted barrier dysfunction in an endothelial cell layer in vitro, and administration of a PKC-δ-specific inhibitor significantly increased steady state vascular permeability. A neutrophil transmigration assay indicated that the PKC-δ inhibition increased neutrophil transmigration through an endothelial monolayer. This suggests that PKC-δ inhibition induces structural changes in endothelial cells, allowing extravasation of proteins and neutrophils.

Numerical modeling of diamond growth environment in hfcvd reactors

A numerical model of the diamond growth environment in a hot-filament chemical vapor deposition (HFCVD) system has been developed The model combines equations of the conservation of mass, momentum, energy and chemical species with appropriate boundary conditions The combined partial differential equations were solved numerically using the finite-volume method Then the model was used to investigate the effects of gas-phase diffusion, CH4 concentration and the filament temperature on the production of CH3 that is known as the diamond precursor in the HFCVD system From the result, the predicted chemical species concentrations agreed well with previously measured experimental values and the concentration of CH is shown to increase as the CH4 concentration and the filament temperature increase It is also known that, although acetylene (C H3) is a dominant chemical species in the equilibrium state of the C-H system at filament temperature, methyl (CH3), which is a precursor of the diamond, is more plentiful than H3 in a real HFCVD reactor because of the gas-phase diffusion

Severe hypotension following urethral catheterization during general anesthesia in a patient with bladder cancer -A case report-

The process of micturition is related to activation of the cardiovascular autonomic nervous system. Hypotension with bradycardia often occurs during or immediately after micturition. We experienced a case of sudden severe hypotension and bradycardia following urethral catheterization in a patient who underwent an urethral dilatation and transurethral resection of bladder tumor while under general anesthesia. The patient was treated with inotropics and intravenous fluids, and he recovered without any complications. The characteristics of this case are similar to the physiologic changes that occur in micturition syncope. Therefore, it is presumed that the autonomic reflex that was triggered by the urethral catheterization caused the hypotension and bradycardia.