Young Jun Oh

Pulmonary edema after da Vinci-assisted laparoscopic radical prostatectomy: a case report.

A 63 year-old man developed sudden pulmonary edema after uneventful robot-assisted laparoscopic radical prostatectomy (RALP) for prostate cancer despite normal preoperative laboratory findings and appropriate anesthetic management. The pulmonary edema was attributed to prolonged (4 hrs) pneumoperitoneum with concomitant high intraabdominal pressure (15-20 mmHg).

Two distinct mechanisms are involved in 6-hydroxydopamine- and MPP+- induced dopaminergic neuronal cell death: Role of caspases, ROS, and JNK

In this study, we examined the possibility that MPTP and 6‐hydroxydopamine (6‐OHDA) act on distinct cell death pathways in a murine dopaminergic neuronal cell line, MN9D. First, we found that cells treated with 6‐OHDA accompanied ultrastructural changes typical of apoptosis, whereas MPP+ treatment induced necrotic manifestations. Proteolytic cleavage of poly(ADP‐ribose)polymerase by caspase was induced by 6‐OHDA, whereas it remained uncleaved up to 32 h after MPP+ treatment and subsequently disappeared. Accordingly, 6‐OHDA‐ but not MPP+‐induced cell death was significantly attenuated in the presence of a broad‐spectrum caspase inhibitor, N‐benzyloxy‐carbonyl‐Val‐Ala‐Asp‐fluomethylketone (Z‐VAD‐fmk). As measured by fluorometric probes, the level of reactive oxygen species (ROS) significantly increased after 6‐OHDA treatment. In contrast, the level of dihydroethidium‐sensitive ROS following MPP+ treatment remained unchanged while a slight increase in dichlorofluorescin‐sentive ROS was temporarily observed. As demonstrated by immunoblot analysis, the level of superoxide dismutase was down‐regulated following 6‐OHDA treatment, whereas it remained unchanged after MPP+ treatment. Cotreatment of cells with antioxidants such as N‐acetylcysteine or Mn(III)tetrakis(4‐benzoic acid)porphyrin chloride (MnTBAP, cell‐permeable superoxide dismutase mimetic) rescued 6‐OHDA‐ but not MPP+‐induced cell death, whereas inclusion of catalase or NG‐nitro‐l‐arginine had no effect in both cases. In addition, 6‐OHDA induced ROS‐mediated c‐Jun N‐terminal kinase (JNK) activation that was attenuated in the presence of N‐acetylcysteine or MnTBAP but not catalase or Z‐VAD‐fmk. In contrast, MPP+ has little effect on JNK activity, indicating that ROS and/or ROS‐induced cell death signaling pathway seems to play an essential role in 6‐OHDA–mediated apoptosis but not in MPP+‐induced necrosis in a mesencephalon‐derived, dopaminergic neuronal cell line. J. Neurosci. Res. 57:86–94, 1999.

Minocycline Reduces Cell Death and Improves Functional Recovery after Traumatic Spinal Cord Injury in the Rat

We examined the effects of minocycline, an anti-inflammatory drug, on functional recovery following spinal cord injury (SCI). Rats received a mild, weight-drop contusion injury to the spinal cord and were treated with the vehicle or minocycline at a dose of 90 mg/kg immediately after SCI and then twice at a dose of 45 mg/kg every 12 h. Injecting minocycline after SCI improved hind limb motor function as determined by the Basso-Beattie-Bresnahan (BBB) locomotor open field behavioral rating test. Twenty four to 38 days after SCI, BBB scores were significantly higher in minocycline-treated rats as compared with those in vehicle-treated rats. Morphological analysis showed that lesion size increased progressively in both vehicle-treated and minocycline-treated spinal cords. However, in response to treatment with minocycline, the lesion size was significantly reduced at 21-38 days after SCI when compared to the vehicle control. Minocycline treatment significantly reduced the number of terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL)-positive cells 24 h after SCI as compared to that of the vehicle control. DNA gel electrophoresis also revealed a marked decrease in DNA laddering in response to treatment with minocycline. In addition, minocycline treatment significantly reduced the specific caspase-3 activity after SCI as compared to that of vehicle control. Furthermore, RT-PCR analyses revealed that minocycline treatment increased expression of interleukin-10 mRNA but decreased tumor necrosis factor-alpha expression. These data suggest that, after SCI, minocycline treatment modulated expression of cytokines, attenuated cell death and the size of lesions, and improved functional recovery in the injured rat. This approach may provide a therapeutic intervention enabling us to reduce cell death and improve functional recovery after SCI.

Minocycline Alleviates Death of Oligodendrocytes by Inhibiting Pro-Nerve Growth Factor Production in Microglia after Spinal Cord Injury

Spinal cord injury (SCI) causes a permanent neurological disability, and no satisfactory treatment is currently available. After SCI, pro-nerve growth factor (proNGF) is known to play a pivotal role in apoptosis of oligodendrocytes, but the cell types producing proNGF and the signaling pathways involved in proNGF production are primarily unknown. Here, we show that minocycline improves functional recovery after SCI in part by reducing apoptosis of oligodendrocytes via inhibition of proNGF production in microglia. After SCI, the stress-responsive p38 mitogen-activated protein kinase (p38MAPK) was activated only in microglia, and proNGF was produced by microglia via the p38MAPK-mediated pathway. Minocycline treatment significantly reduced proNGF production in microglia in vitro and in vivo by inhibition of the phosphorylation of p38MAPK. Furthermore, minocycline treatment inhibited p75 neurotrophin receptor expression and RhoA activation after injury. Finally, minocycline treatment inhibited oligodendrocyte death and improved functional recovery after SCI. These results suggest that minocycline may represent a potential therapeutic agent for acute SCI in humans.

Arginase inhibition restores NOS coupling and reverses endothelial dysfunction and vascular stiffness in old rats

There is increasing evidence that upregulation of arginase contributes to impaired endothelial function in aging. In this study, we demonstrate that arginase upregulation leads to endothelial nitric oxide synthase (eNOS) uncoupling and that in vivo chronic inhibition of arginase restores nitroso-redox balance, improves endothelial function, and increases vascular compliance in old rats. Arginase activity in old rats was significantly increased compared with that shown in young rats. Old rats had significantly lower nitric oxide (NO) and higher superoxide (O2(-)) production than young. Acute inhibition of both NOS, with N(G)-nitro-l-arginine methyl ester, and arginase, with 2S-amino- 6-boronohexanoic acid (ABH), significantly reduced O2(-) production in old rats but not in young. In addition, the ratio of eNOS dimer to monomer in old rats was significantly decreased compared with that shown in young rats. These results suggest that eNOS was uncoupled in old rats. Although the expression of arginase 1 and eNOS was similar in young and old rats, inducible NOS (iNOS) was significantly upregulated. Furthermore, S-nitrosylation of arginase 1 was significantly elevated in old rats. These findings support our previously published finding that iNOS nitrosylates and activates arginase 1 (Santhanam et al., Circ Res 101: 692-702, 2007). Chronic arginase inhibition in old rats preserved eNOS dimer-to-monomer ratio and significantly reduced O2(-) production and enhanced endothelial-dependent vasorelaxation to ACh. In addition, ABH significantly reduced vascular stiffness in old rats. These data indicate that iNOS-dependent S-nitrosylation of arginase 1 and the increase in arginase activity lead to eNOS uncoupling, contributing to the nitroso-redox imbalance, endothelial dysfunction, and vascular stiffness observed in vascular aging. We suggest that arginase is a viable target for therapy in age-dependent vascular stiffness.

Activation of c-Jun N-terminal Kinase Antagonizes an Anti-apoptotic Action of Bcl-2

Bcl-2 is an intracellular membrane-associated protein that prevents cell death induced by a variety of apoptotic stimuli. A mechanism by which Bcl-2 exerts an anti-cell death effect is, however, not fully understood. In the present study, Bcl-2 suppressed cell death of N18TG neuroglioma cells caused by various apoptotic stresses, including etoposide, staurosporine, anisomycin, and ultraviolet irradiation. Concomitantly, Bcl-2 disrupted a signaling cascade to the c-Jun N-terminal kinase activation induced by the apoptotic stresses. Bcl-2 also prevented the etoposide-induced stimulation of MEKK1. Furthermore, overexpression of c-Jun N-terminal kinase antagonized the death-protective function of Bcl-2. These data suggest that suppression of the c-Jun N-terminal kinase signaling pathway may be critical for Bcl-2 action.

Cleavage of Bax is mediated by caspase‐dependent or ‐independent calpain activation in dopaminergic neuronal cells: protective role of Bcl‐2

Two cysteine protease families, caspase and calpain, are known to participate in cell death. We investigated whether a stress‐specific protease activation pathway exists, and to what extent Bcl‐2 plays a role in preventing drug‐induced protease activity and cell death in a dopaminergic neuronal cell line, MN9D. Staurosporine (STS) induced caspase‐dependent apoptosis while a dopaminergic neurotoxin, MPP+ largely induced caspase‐independent necrotic cell death as determined by morphological and biochemical criteria including cytochrome c release and fluorogenic caspase cleavage assay. At the late stage of both STS‐ and MPP+‐induced cell death, Bax was cleaved into an 18‐kDa fragment. This 18‐kDa fragment appeared only in the mitochondria‐enriched heavy membrane fraction of STS‐treated cells, whereas it was detected exclusively in the cytosolic fraction of MPP+‐treated cells. This proteolytic cleavage of Bax appeared to be mediated by calpain as determined by incubation with [35S]methionine‐labelled Bax. Thus, cotreatment of cells with calpain inhibitor blocked both MPP+‐ and STS‐induced Bax cleavage. Intriguingly, overexpression of baculovirus‐derived inhibiting protein of caspase, p35 or cotreatment of cells with caspase inhibitor blocked STS‐ but not MPP+‐induced Bax cleavage. This appears to indicate that calpain activation may be either dependent or independent of caspase activation within the same cells. However, cotreatment with calpain inhibitor rescued cells from MPP+‐induced but not from STS‐induced neuronal cell death. In these paradigms of dopaminergic cell death, overexpression of Bcl‐2 prevented both STS‐ and MPP+‐induced cell death and its associated cleavage of Bax. Thus, our results suggest that Bcl‐2 may play a protective role by primarily blocking drug‐induced caspase or calpain activity in dopaminergic neuronal cells.

Systemic administration of 17β-estradiol reduces apoptotic cell death and improves functional recovery following traumatic spinal cord injury in rats

Recent evidence indicates that estrogen exerts neuroprotective effects in both brain injury and neurodegenerative diseases. We examined the protective effect of estrogen on functional recovery after spinal cord injury (SCI) in rats. 17β-estradiol (3, 100, or 300 μg/kg) was administered intravenously 1-2 h prior to injury (pre-treatment), and animals were then subjected to a mild, weight-drop spinal cord contusion injury. Estradiol treatment significantly improved hind limb motor function as determined by the Basso-Beattie-Bresnahan (BBB) locomotor open field behavioral rating test. Fifteen to 30 days after SCI, BBB scores were significantly higher in estradiol-treated (100 μg/kg) rats when compared to vehicle-treated rats. Morphological analysis showed that lesion sizes increased progressively in either vehicle-treated or 17β-estradiol-treated spinal cords. However, in response to treatment with 17β-estradiol, the lesion size was significantly reduced 18-28 days after SCI when compared to vehicle-treated ...

ACTIVATION OF CASPASE- 3 PROTEASE VIA A BCL-2-INSENSITIVE PATHWAY DURING THE PROCESS OF GINSENOSIDE RH2-INDUCED APOPTOSIS

We have demonstrated that ginsenoside Rh2 (G-Rh2), a ginseng saponin with a dammarane skeleton, induces apoptosis of human hepatoma SK-HEP-1 cells as evidenced by analyses of DNA fragmentation, flow cytometry and changes in cell morphology. Ac-YVAD-CMK or Ac-DEVD-CHO effectively prevented G-Rh2-induced DNA fragmentation, indicating the involvement of caspase-like proteases in the process of apoptosis. In addition, G-Rh2 induced the processing of caspase-3 to an active form, p17. In stable Bcl-2 transfectants, G-Rh2 also induced DNA fragmentation, while staurosporine-induced DNA fragmentation was totally blocked. As it did in wild-type cells, G-Rh2 induced the proteolytic activation of caspase-3 protease and subsequent cleavage of PARP in the bcl-2 transfectants. In summary, G-Rh2 contains an apoptotic inducing activity in SK-HEP-1 cells which functions via Bcl-2-insensitive activation of caspase-3, followed by proteolytic cleavage of PARP.

Minocycline inhibits apoptotic cell death via attenuation of TNF‐α expression following iNOS/NO induction by lipopolysaccharide in neuron/glia co‐cultures

We attempted to ascertain the neuroprotective effects and mechanisms of minocycline in inflammatory‐mediated neurotoxicity using primary neuron/glia co‐cultures treated with lipopolysaccharide (LPS). Neuronal cell death was induced by treatment with LPS for 48 h, and the cell damage was assessed using lactate dehydrogenase (LDH) assays and by counting microtubule‐associated protein‐2 (MAP‐2) positive cells. Through terminal transferase deoxyuridine triphosphate‐biotin nick end labeling (TUNEL)‐staining and by measuring caspase‐3 activity, we found that LPS‐induced neuronal cell death was mediated by apoptosis. We determined that pre‐treatment with minocycline significantly inhibited LPS‐induced neuronal cell death. In addition, LPS induced inducible nitric oxide synthase (iNOS) expression significantly, resulting in nitric oxide (NO) production within glial cells, but not in neurons. Both nitric oxide synthase (NOS) inhibitors (NG‐monomethyl‐l‐arginine monoacetate (l‐NMMA) and S‐methylisothiourea sulfate (SMT)) and minocycline inhibited iNOS expression and NO release, and increased neuronal survival in neuron/glia co‐cultures. Pre‐treatment with minocycline significantly inhibited the rapid and extensive production of tumor necrosis factor‐alpha (TNF‐α) mediated by LPS in glial cells. We also determined that the signaling cascade of LPS‐mediated iNOS induction and NO production was mediated by TNF‐α by using neutralizing antibodies to TNF‐α. Consequently, our results show that the neuroprotective effect of minocycline is associated with inhibition of iNOS induction and NO production in glial cells, which is mediated by the LPS‐induced production of TNF‐α.