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S Hwang,
D Y Kim,
C S Ahn,
D B Moon,
K M Kim,
G C Park,
J M Namgoong,
S W Jung, S Y Yoon,
Y H Park,
S G Lee
[show abstract]
[hide abstract]
ABSTRACT: To enhance the technical feasibility of portal vein (PV) interposition grafting for pediatric PV hypoplasia, we performed a computational simulation to establish a customized surgical technique allowing a secure anastomosis of an iliac vein graft to a severely hypoplastic PV stump.
Based on the literature and on our own experience with reconstruction of PV hypoplasia, we devised three types of recipient PV stump preparations and three types of interposition vein grafts, yielding five technically feasible combinations.
The computational simulation model for PV reconstruction using an interposition vein graft revealed the most feasible combination to be a sequential inverted-T incision to the confluence of the superior mesenteric vein and splenic vein with a longitudinal slit in the transverse vein graft end, the technical feasibility was validated by an artificial suture model. This reconstruction was clinically applied to treat a 7.2-kg 10-month-old female patient with biliary atresia and a severely hypoplastic PV. The PV reconstruction was successful; the patient recovered uneventfully.
We have presented a simplified surgical technique for PV interposition that is applicable to pediatric PV hypoplasia, which also appears to be a feasible option for pediatric liver transplantation.
Transplantation Proceedings 01/2013; 45(1):255-8. · 1.00 Impact Factor
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C-S Park,
S Hwang,
H-W Park,
Y-H Park,
H-J Lee,
J-M Namgoong, S-Y Yoon,
S-W Jung,
G-C Park,
D-H Jung,
G-W Song,
D-B Moon,
C-S Ahn,
K-H Kim,
T-Y Ha,
S-W Kwon,
S-G Lee
[show abstract]
[hide abstract]
ABSTRACT: Severe early graft dysfunction has been occasionally encountered following adult living donor liver transplantation (LDLT). We have assessed the effectiveness of plasmapheresis (PP) as liver support for LDLT recipients with severe early graft dysfunction.
Of the 789 adult LDLTs performed between January 2007 and December 2009, 50 patients (6.3%) underwent PP as a supportive measure during the first month.
The mean time from LDLT to start of plasmapheresis was 11.2 ± 6.8 days (range 2-28). The 50 patients underwent 517 sessions of PP, or a mean of 10.3 ± 6.8 sessions per patient, over a mean 21.6 ± 9.4 days. Thirty-four patients (68%) required concurrent hemodiafiltration. Mean serum total bilirubin concentration before PP was 16.2 ± 6.7 mg/dL, peaking at 20.3 ± 7.9 mg/dL during PP, and decreasing to 13.4 ± 5.4 mg/dL 1 week after completion of PP (P < .001 compared with before PP). Except for prothrombin time, no other biochemical parameter was significantly altered by PP. There were no serious complications related to PP. Of the 50 patients, 17 (34%) died soon or a few months after PP. The 6-month graft survival rate after completion of PP was 66%; the overall 1-year patient survival rate was 64.0%.
PP appeared to have beneficial effects for LDLT recipients with severe early graft dysfunction, namely total bilirubin concentrations greater than 10 mg/dL.
Transplantation Proceedings 04/2012; 44(3):749-51. · 1.00 Impact Factor
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H W Park,
S Hwang,
C S Ahn,
K H Kim,
D B Moon,
T Y Ha,
G W Song,
D H Jung,
G C Park,
J M Namgoong, S Y Yoon,
C S Park,
Y H Park,
H J Lee,
S G Lee
[show abstract]
[hide abstract]
ABSTRACT: De novo malignancy is not uncommon after liver transplantation (OLT). We have compared the incidence of novo malignancy following OLT with those among the general Korean population.
Between January 1998 and December 2008, 1952 adult OLT were performed, including 1714 living donor and 238 deceased donor grafts whose medical records were retrospectively reviewed.
Among the 1952 patients, 44 (2.3%) showed de novo malignancies after a mean posttransplant period of 41 months. Among the 14 types of malignancy the most frequent was stomach cancer (n = 11; 25.0%), colorectal cancer (n = 9; 20.5%), breast cancer (n = 4; 9.1%), and thyroid cancer (n = 3; 6.8%). These patients underwent aggressive treatment, including surgery, chemotherapy, and radiotherapy, except for one patient with an aggressive primary liver cancer. Over a mean follow-up of 45 months after diagnosis of de novo malignancy, 13 patients (29.5%) died; the overall 3-year patient survival rate was 67.5%. The relative risk of malignancy following OLT was 7.7-fold higher in men and 7.3-fold higher in women than the Korean general population.
OLT recipients must be checked periodically for de novo malignancy throughout their lives, especially for cancers common in the general population.
Transplantation Proceedings 04/2012; 44(3):802-5. · 1.00 Impact Factor
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Y-H Park,
S Hwang,
H-W Park,
C-S Park,
H-J Lee,
J-M Namgoong, S-Y Yoon,
S-W Jung,
G-W Song,
G-C Park,
D-H Jung,
C-S Ahn,
K-H Kim,
D-B Moon,
T-Y Ha,
S-G Lee
[show abstract]
[hide abstract]
ABSTRACT: Adult liver transplantation (OLT) recipients occasionally show serious acute cardiopulmonary dysfunction, requiring intensive care. We assessed the role of extracorporeal membrane oxygenation (ECMO) support in adult recipients facing acute pulmonary failure and refractory to conventional mechanical ventilation and concurrent nitric oxide gas inhalation.
From January 2008 to March 2011, 18 adult OLT recipients at our institution required ECMO support: 12 due to pneumonia and 6 to adult respiratory distress syndrome. Their mean age was 55.7 ± 6.9 years and mean Model for End-stage Liver Disease score, 24.8 ± 8.5. Twelve patients had undergone living donor and six deceased donor OLT.
A venovenous access mode and concurrent continuous venovenous hemodiafiltration were used in all patients. There were no procedure-related complications. Eight patients (44.4%) were successfully weaned from ECMO upon the first attempt after a mean support of 11.9 ± 6.1 days, but the other 10 died due to overwhelming infection. Univariate analysis revealed no significant pre-ECMO risk factor for treatment failure but C-reactive protein concentration at the time of ECMO differed significantly among patients who did versus did not survive after ECMO.
ECMO as rescue therapy may be a final therapeutic option for OLT recipients with refractory pulmonary dysfunction who would otherwise die due to hypoxemia from severe pneumonia or adult respiratory distress syndrome.
Transplantation Proceedings 04/2012; 44(3):757-61. · 1.00 Impact Factor
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J W Jung,
S Hwang,
J M Namgoong, S Y Yoon,
C S Park,
Y H Park,
H J Lee,
H W Park,
G C Park,
D H Jung,
G W Song,
T Y Ha,
C S Ahn,
K H Kim,
D B Moon,
G Y Ko,
K B Sung,
S G Lee
[show abstract]
[hide abstract]
ABSTRACT: To assess the incidence and management of postoperative abdominal bleeding after orthotopic liver transplantation (OLT) and to identify risk factors for abdominal bleeding.
We retrospectively reviewed the medical records of 1039 patients who underwent OLT at our institution from January 2008 to December 2010 seeking to identify subjects with posttransplantation abdominal bleeding, defined as any hemorrhage requiring radiologic intervention or laparotomy within the first month.
Among the 1039 patients, 94 (9%) showed abdominal bleeding, occurring at a mean of 6.1 days (range, day 1 to 21 days). Active bleeding was controlled by endovascular interventional techniques (n = 37; 39%), by surgical ligation or vascular reconstruction (n = 43; 46%), or by sequential combinations of endovascular intervention and surgery (n = 14; 15%). The most frequent bleeding sites for radiologic intervention were the right inferior phrenic artery (n = 14), right and left epigastric arteries (n = 7), intercostal artery (n = 5) and right renal capsular artery (n = 4). The most frequent bleeding sites requiring laparotomy were the hepatic artery (n = 9), diaphragm (n = 8), inferior vena cava (n = 5), abdominal drain insertion site (n = 4), portal vein anastomosis site (n = 4), abdominal wall (n = 3), liver graft cut surface (n = 3), hilar plate (n = 3), and greater omentum (n = 3). Bleeding episodes were associated with greater patient age and increased intraoperative blood loss.
The risk of bleeding from coagulopathy and iatrogenic injury is high during the early posttransplantation period. This risk of bleeding can be minimized by meticulous surgical dissection and bleeding control.
Transplantation Proceedings 04/2012; 44(3):765-8. · 1.00 Impact Factor
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W-Y Chae,
S Hwang,
Y-I Yoon,
M-C Kang,
D-B Moon,
G-W Song,
G-C Park,
D-H Jung,
J-M Namgoong,
S-W Jung, S-Y Yoon,
J-J Kim,
G-S Hwang,
S-G Lee
[show abstract]
[hide abstract]
ABSTRACT: Patients with advanced liver diseases are at increased risk of cardiovascular events, resulting in a higher incidence of cardiac complications following liver transplantation (OLT). We assessed the clinical value of computed tomographic coronary arteriography (CTCAG) as a routine preoperative cardiac evaluation test in adult patients scheduled for living donor OLT (LDLT).
This single-center, prospective, observational study evaluated 247 adult patients being assessed for LDLT from April 2010 to March 2011. CTCAG was performed in patients with all-negative findings on routine cardiac workup, including thallium single photon emission computed tomography (SPECT).
Of the 247 patients evaluated, 27 (10.9%) showed abnormal findings on CTCAG, with 18 (7.3%) showing mild to moderate involvement of one vessel; 7 (2.8%), two-vessel; and 2 (0.8%), three-vessel involvement. Coronary artery calcification was identified in patients with significant coronary artery stenosis. No adverse events occurred after CTCAG. Noticeable hypotensive episodes during LDLT surgery occurred in 5% of patients, mostly related to massive bleeding or postperfusion syndrome. During the first 3 months after LDLT, 3% of patients showed stress cardiomyopathy, but all recovered with supportive care.
The poor general medical condition of LDLT candidates and the diagnostic accuracy of CTCAG suggest that this test should be included in the routine pretransplant cardiac workup, along with thallium SPECT, for these patients.
Transplantation Proceedings 03/2012; 44(2):415-7. · 1.00 Impact Factor
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C-S Ahn,
S Hwang,
D-B Moon,
G-W Song,
T-Y Ha,
G-C Park,
J-M Namgoong, S-Y Yoon,
S-W Jung,
D-H Jung,
K-H Kim,
Y-H Park,
H-W Park,
H-J Lee,
C-S Park,
S-G Lee
[show abstract]
[hide abstract]
ABSTRACT: Sufficient arterial flow after living donor liver transplantation (LDLT) is closely related to graft survival and prevention of postoperative complications. However, some unfavorable hepatic arterial conditions in recipients preclude reconstruction, requiring alternative stumps. We have used the right gastroepiploic artery (RGEA) as a first alternative for hepatic inflow.
From January 2006 to December 2008, we performed 754 LDLTs including 28 cases of RGEA among hepatic arterial anastomoses. The arterial anastomosis was performed by an single surgeon under 859 a microscope using an end-to-end interrupted suture technique. RGEA was mobilized over 15 cm from the greater curvature of stomach and greater omentum.
The indications for RGEA use included severe hepatic arterial injury from previous transarterial chemoembolization (n=14), need for additional arterial flow in dual-grafts LDLT (n=13), poor blood flow from the recipient hepatic artery (n=3), and arterial injury during hilar dissection (n=3). The mean diameter of the isolated RGEA was 2.0±0.2 mm (range: 1.0-2.5). Most hepatic arterial anastomoses were performed with a significant size discrepancy of more than twofold. All reconstructed hepatic arterial flowes showed good; no complication was identified during the mean follow-up period of 56 months to date.
Using RGEA as an alternative arterial inflow is a simple, reliable procedure for situations of inadequate recipient hepatic or multiple graft arteries.
Transplantation Proceedings 03/2012; 44(2):451-3. · 1.00 Impact Factor
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H-J Lee,
S Hwang,
C-S Ahn,
K-H Kim,
D-B Moon,
T-Y Ha,
G-W Song,
D-H Jung,
G-C Park,
J-M Namgoong, S-Y Yoon,
S-W Jung,
H-W Park,
C-S Park,
Y-H Park,
S-G Lee
[show abstract]
[hide abstract]
ABSTRACT: Anomalous portal vein (PV) branching in living donor livers is not uncommon and usually leads to double PV orifices of the right lobe grafts. We have assessed the long-term outcomes of portal Y-graft interposition for adult living donor liver transplantation (LDLT).
We retrospectively assessed the outcomes of 79 right-lobe LDLTs using portal Y-graft interposition among the 2001 adult LDLTs performed at our institution from January 2002 to December 2010.
Donor PV types were type III except for one case of type II. Sources of Y-grafts were recipient autologous PV in 76 LDLTs, fresh iliac vein allografts in two, and patch plasty using recipient greater saphenous vein in one. Detailed procedures included a portal Y-graft resection with Y-limbs, corner stay sutures, tying of suture materials under direct mechanical dilatation, and direct edge-to-edge anastomosis to the recipient remnant main PV. Early PV stenting was necessary in five patients (6.3%) due to stenosis or buckling deformity. During a mean follow-up of 42 months, all PVs remained patent until patient death or censoring. Overall 1-, 3-, and 5-year patient survival rates were 93.6%, 88.3%, and 85.5%, respectively. None of the 79 donors experienced major complications requiring reoperation or therapeutic intervention.
Due to their technical feasibility and excellent long-term outcome, portal Y-graft interposition should be considered a standard procedure for reconstruction of right-lobe grafts with double PV orifices.
Transplantation Proceedings 03/2012; 44(2):454-6. · 1.00 Impact Factor
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S Hwang,
C S Ahn,
K H Kim,
D B Moon,
T Y Ha,
G W Song,
D H Jung,
G C Park,
J M Namgoong, S Y Yoon,
S W Jung,
S G Lee
[show abstract]
[hide abstract]
ABSTRACT: After >2000 adult living donor liver transplants (LDLTs), we observed minimization of the complication rate using case-by-case modification of venous outflow reconstruction in right liver graft (RLG), standardization seeking intend to provide a hemodynamic- based, regeneration-compliant hepatic outflow reconstruction.
We retrospectively examined 100 consecutive adult LDLT using modified RLG before and after application of RLG standardization to compare the 6-month incidences of vascular outflow complications.
The right hepatic vein stenting rate for first 6 months was 5% in the customized group and 1% in the standardized group (P=.212). The middle hepatic vein stenting rate for first 6 months was 9% in the customized group and 4% in the standardized group (P=.373). The inferior right hepatic vein stenting rate for first 6 months was 12.8% in the customized group and 7.1% in the standardized group (P=.472). The overall 6-month patient survival rate was 94% in the customized group and 95% in the standardized group (P=.867). The overall incidence of significant RLG venous outflow complications was 19% in the customized group and 8% in the standardized group (P=.023).
Standardization as a universal graft model seemed to be more effective and feasible than conventional graft customization requiring individualized case-by-case modification.
Transplantation Proceedings 03/2012; 44(2):457-9. · 1.00 Impact Factor
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[show abstract]
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ABSTRACT: Early intervention and maintenance treatment for schizophrenia patients may prolong the duration of exposure to antipsychotic agents; however, there have been few studies on the neurotoxicity of these agents. Here, we investigated the effects of antipsychotics on cell viability and autophagy in rat primary neurons. Cultured cortical neurons obtained from rat embryos were treated with various concentrations of haloperidol and clozapine, and the neuronal toxicity was assessed by measuring lactate dehydrogenase (LDH) activity and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Autophagosomes were quantitated by measuring the level of microtubule-associated protein 1A/1B-light chain 3 (LC3-II) by Western blot and immunofluorescence staining. Autophagic flux was assayed using bafilomycin A1 and GFP-mCherry-LC3 transfection. Haloperidol and clozapine decreased the viability of neurons in vitro in a concentration- and time-dependent manner. We also observed increased accumulation of autophagosomes after antipsychotic treatment. Using bafilomycin A1 and GFP-mCherry-LC3 transfection, we discovered that haloperidol and clozapine inhibited autophagosome turnover resulting in a dysfunctional autophagic process, including impaired lysosomal fusion. Together, these results suggest that haloperidol and clozapine negatively affect neuronal viability, possibly by blocking autophagolysosome formation.
Neuroscience 02/2012; 209:64-73. · 3.38 Impact Factor
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S Hwang,
Y D Yu,
G C Park,
Y I Choi,
P J Park,
S W Jung,
J M Namgoong, S Y Yoon,
H S Ha,
J J Hong, [......],
J E Ma,
S Y Choi,
J S Yun,
D H Jung,
G W Song,
T Y Ha,
D B Moon,
K H Kimy,
C S Ahn,
S G Lee
[show abstract]
[hide abstract]
ABSTRACT: To evaluate the safety of institutional protocol for ultra-rapid hepatitis B immunoglobulin (HBIG) infusion (10,000 IU in 30 minutes) for hepatitis B virus prophylaxis in adult liver transplant recipients.
In this case-controlled study, prospectively recruited liver transplant recipients received ultra-rapid infusions of HBIG (10,000 units in 30 minutes) for 6 months. The historical control group consisted of patients who had received 1-hour HBIG infusions (conventional rapid infusion) for the precedent 6 months.
We found that 1472 patients had received 5744 ultra-rapid HBIG infusions, whereas 1343 patients had received 5200 conventional rapid HBIG infusions. Adverse side-effects were observed after 7 (0.13%) and 9 (0.16%) infusions, respectively (P = .763). The number of infusions per month increased significantly, from 878 ± 34 before the introduction of ultra-rapid infusion to 957 ± 29 afterwards (P < .001), an increase of 10.5%. The maximal capacity of HBIG infusions per day in the outpatient clinic increased from 53 for conventional rapid infusion to 65 for ultra-rapid infusion, without expansion of the outpatient facility or equipment.
Nearly all adult liver recipients able to tolerate 1-hour infusions of HBIG can also tolerate ultra-rapid infusions well. Thus, it seems to be reasonable to perform ultra-rapid infusion protocol widely for patient convenience.
Transplantation Proceedings 06/2011; 43(5):1780-2. · 1.00 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Phosphorylation of eukaryotic initiation factor-2 alpha (eIF2 alpha) is increased in Alzheimer's disease (AD) and this protein can be phosphorylated by several kinases, including double-stranded RNA-dependent protein kinase (PKR), PKR-like endoplasmic reticulum kinase (PERK), amino acids-regulated eIF2 alpha kinase (GCN2) and heme-regulated eIF2 alpha kinase (HRI). PKR and PERK especially are activated in the AD brain, and GCN2 is reported to increase presenilin-1 (PS1) activity. Okadaic acid (OA), a protein phosphatase-2A (PP2A) inhibitor, is known to increase tau phosphorylation, beta-amyloid (A beta) deposition and neuronal death, which are the pathological characteristics of AD. Here, we show that the phosphorylation of eIF2 alpha is increased and its kinases, PKR, PERK and GCN2 are activated in rat neurons by OA. Activating transcription factor (ATF4) which induces apoptosis in response to eIF2 alpha phosphorylation was increased and translocated to nuclei in OA-treated neurons. These results suggest that the successive events of activation of eIF2 alpha kinases and eIF2 alpha phosphorylation leading to ATF4 nuclear translocation may contribute to neuronal death. However, PKR inhibitors did not reduce eIF2 alpha phosphorylation or neuronal toxicity despite inhibiting PKR activity. These results suggest that PKR might not be the most responsible kinase for eIF2 alpha phosphorylation or cell death in PP2A-inhibited conditions such as AD.
Neuroscience 09/2010; 169(4):1831-9. · 3.38 Impact Factor
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[hide abstract]
ABSTRACT: Mycophenolic acid (MPA), an inosine monophosphate dehydrogenase inhibitor, is widely used as an immunosuppressive drug after transplantations including those of pancreas islet cells. However, recent reports have indicated that MPA has apoptotic effects on islet cells in vitro. To study the effect of MPA on islet cells and determine its mechanism, we used an insulin secreting cell-line, HIT-T15. We examined mitogen-activated protein kinase (MAPK) activation after MPA treatment, and determining cell death levels using methylthiazdetetrazolium assays. The activations of extracellular signal-regulated protein kinase (ERK), c-jun N-terminal kinase (JNK), and p38 MAPK and caspase-3 cleavage were measured by Western blotting. MPA (1, 10, 30 micromol/L) increased cell death and caspase-3 cleavage within 24 hours. Exogenous 500 micromol/L guanosine reversed the MPA-induced islet cell death, but exogenous adenosine did not. MPA 10 micromol/L induced cell apoptosis and increased the activations of JNK, ERK, and p38 MAPK. Furthermore, exogenous guanosine, but not exogenous adenosine, reversed these effects induced by MPA. This study demonstrated that MPA may induce islet apoptosis in HIT-T15 cells by increasing activations of JNK, ERK, and p38 MAPK in a guanosine-dependent manner.
Transplantation Proceedings 01/2007; 38(10):3277-9. · 1.00 Impact Factor
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ABSTRACT: Neuronal stimulation was induced in rats by systemic administration of kainic acid (KA) to determine if such stimulation is responsible for changes in the expression patterns of c-Kit and stem cell factor (SCF) in cerebellar synapses between inhibitory interneurons and Purkinje cells. Using immunocytochemistry and immunoblotting analyses, we demonstrate that c-Kit receptor tyrosine kinase and its ligand SCF are present on the pre- and postsynaptic sides of inhibitory synapses on Purkinje cells. These proteins are upregulated during the first 48 hr after KA treatment, whereas their levels fall below that of the control by 1 week and remain as such thereafter. Expression of both c-Kit and SCF are significantly elevated in the Purkinje cell layer 24 hr after KA administration, and the Purkinje cell layer exhibits a loss of calbindin D-28K immunoreactivity. Expression of c-Kit in basket cell axon terminals is activated until 48 hr after KA treatment, suggesting the transient participation of c-Kit receptor tyrosine kinase in the maintenance of these axonal terminals. Also during the first 48 hr after KA treatment, SCF levels increase in axonal processes of Purkinje cells, and these SCF-positive axons correlate with c-Kit-positive pinceau structures. The increased expression of c-Kit and SCF in response to KA-induced neuronal stimulation may indicate that c-Kit receptor tyrosine kinase and its ligand SCF function in the inhibitory synapse between cerebellar interneurons and Purkinje cells, and that this role is most pronounced during the first 48 hr after KA treatment.
Journal of Neuroscience Research 02/2003; 71(1):72-8. · 2.74 Impact Factor
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ABSTRACT: The effects of neurotoxins on levels of mitochondrially encoded gene transcripts in a dopaminergic neuronal cell line, MN9D, were examined following treatment with 200 microM N-methyl-4-phenylpyridinium (MPP(+)) or 6-hydroxydopamine (6-OHDA). As confirmed by a Northern blot analysis, levels of cytochrome c oxidase subunit 3 (COX III) and ATPase subunit 6 (ATPase 6) transcript were decreased in a time-dependent manner following treatment with MPP(+) but not with 6-OHDA. Accordingly, enzymatic activity of cytochrome c oxidase (COX) and the intracellular ATP content were also decreased in MPP(+)-treated cells while these remained unaltered in 6-OHDA-treated cells. In the cell death paradigm induced by MPP(+), overexpression of Bcl-2 in MN9D cells (MN9D/Bcl-2) significantly blocked MPP(+)-induced downregulation of COX III and ATPase 6 transcripts. In MN9D/Bcl-2 cells, MPP(+)-induced downregulation of COX activity and the intracellular level of ATP was also blocked. Treatment with a pan-caspase inhibitor, however, neither prevented MPP(+)-induced downregulation of COX activity nor affected intracellular level of ATP in MN9D cells. Taken together, our present data suggest that Bcl-2 may play a regulatory role in energy metabolism by preventing downregulation of mitochondrially encoded gene(s) at a point distinct from its known anticaspase activity in MPP(+)-induced dopaminergic neuronal death.
Biochemical and Biophysical Research Communications 09/2001; 286(3):659-65. · 2.48 Impact Factor
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ABSTRACT: To examine the correlation between the structure of Bcl-2 and its inhibitory function of c-Jun N-terminal kinase (JNK) and caspase activity, we established a dopaminergic neuronal cell line, MN9D overexpressing Bcl-2 (MN9D/Bcl-2) or its structural mutants. The mutants comprised a point mutation in the BH1 (G145A; MN9D/BH1) or BH2 (W188A; MN9D/BH2) domain and a deletion mutation in the C-terminal (MN9D/C22), BH3 (MN9D/BH3), or BH4 (MN9D/BH4) domain. As determined by the TUNEL (terminal deoxynucleotidyltransferase nick end-labeling) and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction assay, apoptotic death of MN9D/Neo cells reached 80-90% within 24 h in response to 1 microM staurosporine. Upon staurosporine treatment, JNK activity increased six- to sevenfold over the basal level within 2-4 h. Treatment of MN9D/Neo with both staurosporine and a caspase inhibitor, Z-VAD, attenuated cell death without suppressing JNK activation. Both staurosporine-induced cell death and JNK activation were attenuated in MN9D/Bcl-2. As determined by cleavage of poly(ADP-ribose) polymerase into 85 kDa, Bcl-2 blocked caspase activity as well. When cells overexpressing one of the Bcl-2 mutants were treated with staurosporine, death was attenuated in MN9D/BH1, MN9D/BH2, and MN9D/C22 but not in MN9D/BH3 and MN9D/BH4. Similarly, both JNK and caspase activation were blocked in MN9D/BH1, MN9D/BH2, and MN9D/C22, whereas they were not suppressed in MN9D/BH3 and MN9D/BH4. Taken together, our data indicate that there exists a close structural and functional correlation of Bcl-2 to JNK and caspase activity in staurosporine-induced dopaminergic neuronal cell death.
Journal of Neurochemistry 05/2000; 74(4):1621-6. · 4.06 Impact Factor
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ABSTRACT: 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 N(G)-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.
Journal of Neuroscience Research 08/1999; 57(1):86-94. · 2.74 Impact Factor
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ABSTRACT: Phosphorylation of eukaryotic initiation factor-2α (eIF2α) is increased in Alzheimer's disease (AD) and this protein can be phosphorylated by several kinases, including double-stranded RNA-dependent protein kinase (PKR), PKR-like endoplasmic reticulum kinase (PERK), amino acids-regulated eIF2α kinase (GCN2) and heme-regulated eIF2α kinase (HRI). PKR and PERK especially are activated in the AD brain, and GCN2 is reported to increase presenilin-1 (PS1) activity. Okadaic acid (OA), a protein phosphatase-2A (PP2A) inhibitor, is known to increase tau phosphorylation, β-amyloid (Aβ) deposition and neuronal death, which are the pathological characteristics of AD. Here, we show that the phosphorylation of eIF2α is increased and its kinases, PKR, PERK and GCN2 are activated in rat neurons by OA. Activating transcription factor (ATF4) which induces apoptosis in response to eIF2α phosphorylation was increased and translocated to nuclei in OA-treated neurons. These results suggest that the successive events of activation of eIF2α kinases and eIF2α phosphorylation leading to ATF4 nuclear translocation may contribute to neuronal death. However, PKR inhibitors did not reduce eIF2α phosphorylation or neuronal toxicity despite inhibiting PKR activity. These results suggest that PKR might not be the most responsible kinase for eIF2α phosphorylation or cell death in PP2A-inhibited conditions such as AD.
Neuroscience.
