Hea-Nam Hong

Sequential preoperative ipsilateral hepatic vein embolization after portal vein embolization to induce further liver regeneration in patients with hepatobiliary malignancy.

Objective:To assess the effect of ipsilateral hepatic vein embolization (HVE) performed after portal vein embolization (PVE) on liver regeneration. Summary Background Data:PVE induces shrinkage of the embolized lobe and compensatory enlargement of the non-embolized lobe, but it does not always induce sufficient liver regeneration. There was no effective method to accelerate liver regeneration in addition to PVE yet. Methods:During a 1-year study period, preoperative HVE were performed on 12 patients who had shown limited liver regeneration after PVE awaiting right hepatectomy. The right hepatic vein was embolized with multiple coils after insertion of vena cava filters or vascular plugs. Results:No HVE procedure-related complications occurred, but embolization of the wrong hepatic vein trunk occurred in 1 patient. The increase in blood liver enzymes after HVE was comparable with that after PVE alone. In 9 patients who underwent hepatectomy, the proportions of future liver remnant volume to total liver volume were 34.8% ± 1.5% before PVE, 39.7% ± 0.6% 1 to 2 weeks after PVE, 44.2% ± 1.1% 2 weeks after HVE, and 64.5% ± 6.2% 1 week after right hepatectomy. Cirrhotic livers showed lower regeneration rates following HVE after PVE and 1 patient underwent hepatectomy 17 months after HVE. Immunohistochemistry showed that apoptosis occurred more in the liver area affected by both PVE and HVE than in that affected by PVE alone. Conclusions:Preoperative sequential application of PVE and HVE seems to be safe and effective in facilitating contralateral liver regeneration by inducing more severe liver damage than PVE alone.

Protective effect of ginsenosides, active ingredients of Panax ginseng, on kainic acid-induced neurotoxicity in rat hippocampus

Ginsenosides are known to attenuate glutamate-induced cell injuries in vitro. We investigated the in vivo effect of ginsenosides on kainic acid (KA)-induced neurotoxicity in rat hippocampus using the methods of acid fuchsin (AF) staining and heat-shock protein-70 (HSP-70) immunoreactivity to detect neuronal death and stress, respectively. Pretreatment of ginsenosides (50 or 100 mg/kg for 7 days) via intraperitoneal (i.p.) administration significantly attenuated KA (10 mg/kg i.p.)-induced cell death by decreasing AF-positive neurons in both CA1 and CA3 regions of rat hippocampus compared with KA treatment alone. Pretreatment of ginsenosides (50 or 100 mg/kg for 7 days) via i.p. administration also significantly suppressed KA-induced induction of HSP-70 in both regions of rat hippocampus. These results show that ginsenosides are effective in protecting hippocampal CA1 and CA3 cells against KA-induced neurotoxicity.

Protective effects of ascorbic acid against lead-induced apoptotic neurodegeneration in the developing rat hippocampus in vivo

Lead is a neurotoxin that affects the developing central nervous system and may potentially induce apoptotic cell death. We investigated the effect of ascorbic acid against lead-induced neurotoxicity in the developing rat hippocampus. Female Sprague-Dawley rats were divided into three groups: control group, lead-treated group and lead plus ascorbic acid-treated group. Lead (0.2% lead acetate) was administered to female rats during pregnancy and lactation, in their drinking water. During this period, rats in the lead plus ascorbic acid-treated group received 100 mg/kg/day ascorbic acid, orally. At the end of the treatment, neuronal damage, apoptosis and blood lead levels were determined and the levels of Bax and Bcl-2 were immunodetected in the hippocampus of 21-day-old male pups. Histopathological evaluation demonstrated that ascorbic acid significantly attenuates apoptosis in the developing hippocampus and also spares hippocampal CA1, CA3 and dentate gyrus (DG) neurons. Simultaneous administration of ascorbic acid and lead lowered the level of Bax protein and increased Bcl-2 in pup hippocampus and reduced lead level in blood of dams compared with lead-treated only. Based on these results, it seems that ascorbic acid may potentially be beneficial in treating lead-induced brain injury in the developing rat brain.

The formation of PHF-1 and SMI-31 positive dystrophic neurites in rat hippocampus following acute injection of okadaic acid

Within neurofibrillary tangles and dystrophic neurites of Alzheimers disease (AD), tau protein is hyperphosphorylated. In the present study, we provide evidence that acute injection of okadaic acid (1 mM, 0.5 microliter) into the dorsal hippocampus induces the formation of paired helical filament (PHF)-1, sternberger monoclonals incorporated (SMI)-31, and amyloid precursor protein (APP) positive dystrophic neurites in the lacunosum-molecular layer of CA1 and molecular layer of dentate gyrus. Okadaic acid evoked a marked loss of microtubule associated protein (MAP)-2 immunoreactivity. PHF-1 immunoreactive terminals were fine, and SMI-31 immunoreactive terminals appeared at granular terminals and at the ring-like or elongated dystrophic neurites. APP positive dystrophic neurites exhibited large bulb-like globular terminals. Interestingly, APP dystrophic neurites were co-localized with SMI-31 immunoreactivity in the core. APP immunoreactivity became stronger over 24 h even in vehicle injected area. These results may provide the morphological evidence for the animal model to study dystrophic neurites formation of AD.

Important role of Ser443 in different thermal stability of human glutamate dehydrogenase isozymes1

Molecular biological studies confirmed that two glutamate dehydrogenase isozymes (hGDH1 and hGDH2) of distinct genetic origin are expressed in human tissues. hGDH1 is heat‐stable and expressed widely, whereas hGDH2 is heat‐labile and specific for neural and testicular tissues. A selective deficiency of hGDH2 has been reported in patients with spinocerebellar ataxia. We have identified an amino acid residue involved in the different thermal stability of human GDH isozymes. At 45°C (pH 7.0), heat inactivation proceeded faster for hGDH2 (half life=45 min) than for hGDH1 (half‐life=310 min) in the absence of allosteric regulators. Both hGDH1 and hGDH2, however, showed much slower heat inactivation processes in the presence of 1 mM ADP or 3 mM L‐Leu. Virtually most of the enzyme activity remained up to 100 min at 45°C after treatment with ADP and L‐Leu in combination. In contrast to ADP and L‐Leu, the thermal stabilities of the hGDH isozymes were not affected by addition of substrates or coenzymes. In human GDH isozymes, the 443 site is Arg in hGDH1 and Ser in hGDH2. Replacement of Ser by Arg at the 443 site by cassette mutagenesis abolished the heat lability of hGDH2 with a similar half‐life of hGDH1. The mutagenesis at several other sites (L415M, A456G, and H470R) having differences in amino acid sequence between the two GDH isozymes did not show any change in the thermal stability. These results suggest that the Ser443 residue plays an important role in the different thermal stability of human GDH isozymes.

Coxsackievirus B4-induced neuronal apoptosis in rat cortical cultures

Enterovirus infections of the central nervous system (CNS) are common and important causes of morbidity in immunocompromised children and adults. In this study we identify and characterize coxsackievirus B4-induced neuronal death. To investigate the CNS pathophysiology resulting from this viral infection, cultured rat neurons were infected with coxsackievirus B4 (CVB4) and nuclear morphology, phosphatidylserine (PS) externalization, and the effects of Actinomycin D or cycloheximide (CHX) were examined. CVB4 induced neuronal cell death within 24 h while PS externalization was apparent in cell bodies 16 h after CVB4 infection. Actinomycin D or CHX significantly reduced CVB4 induced-neuronal cell death in a dose-dependent manner. Pretreatment with CHX or actinomycin D also inhibited nuclear condensation, which occurred after CVB4 infection. However, the changes were relatively unresponsive to zVAD-fmk. These results suggest that CVB4 induces CHX- and actinomycin D-sensitive, but zVAD-fmk-insensitive neuronal apoptosis.

Inhibitory effects of gallic acid and quercetin on UDP-glucose dehydrogenase activity.

We have examined polyphenols as potential inhibitors of UDP‐glucose dehydrogenase (UGDH) activity. Gallic acid and quercetin decreased specific activities of UGDH and inhibited the proliferation of MCF‐7 human breast cancer cells. Western blot analysis showed that gallic acid and quercetin did not affect UGDH protein expression, suggesting that UGDH activity is inhibited by polyphenols at the post‐translational level. Kinetics studies using human UGDH revealed that gallic acid was a non‐competitive inhibitor with respect to UDP‐glucose and NAD+. In contrast, quercetin showed a competitive inhibition and a mixed‐type inhibition with respect to UDP‐glucose and NAD+, respectively. These results indicate that gallic acid and quercetin are effective inhibitors of UGDH that exert strong antiproliferative activity in breast cancer cells.

Regulation of glutamate level in rat brain through activation of glutamate dehydrogenase by Corydalis ternata.

When treated with protopine and alkalized extracts of the tuber of Corydalis ternata for one year, significant decrease in glutamate level and increase in glutamate dehydrogenase (GDH) activity was observed in rat brains. The expression of GDH between the two groups remained unchanged as determined by Western and Northern blot analysis, suggesting a post-translational regulation of GDH activity in alkalized extracts treated rat brains. The stimulatory effects of alkalized extracts and protopine on the GDH activity was further examined in vitro with two types of human GDH isozymes, hGDH1 (house-keeping GDH) and hGDH2 (nerve-specific GDH). Alkalized extracts and protopine activated the human GDH isozymes up to 4.8-fold. hGDH2 (nervespecific GDH) was more sensitively affected by 1 mM ADP than hGDH1 (house-keeping GDH) on the activation by alkalized extracts. Studies with cassette mutagenesis at ADP-binding site showed that hGDH2 was more sensitively regulated by ADP than hGDH1 on the activation by Corydalis ternata. Our results suggest that prolonged exposure to Corydalis ternata may be one of the ways to regulate glutamate concentration in brain through the activation of GDH.

Differential activation of caspase-3 at two maturational stages during okadaic acid-induced rat neuronal death

Okadaic acid (OA), a protein phosphatase inhibitor, is used as a research model of Alzheimers disease to induce tau phosphorylation and neuronal death. We reported previously that OA induces neuronal apoptosis of immature neurons (in vitro days (IVD) 3-5), which is inhibited by cycloheximide (CHX). In this study, we demonstrate that CHX fails to prevent OA-induced neuronal death in mature neurons (IVD 14-15). Upon comparison of both types of dying cells, the immature neurons displayed characteristic features of apoptosis, such as nuclear fragmentation, phosphatidylserine externalization and prominent caspase-3 activation, while the mature neurons showed few characteristic features of apoptosis. Lack of the beneficial effects of CHX and the lesser activation of caspase-3 in the mature neurons argue against typical apoptotic neuronal death in the OA-induced neurodegeneration model.

Characterization of nonpolio enteroviruses recovered from patients with aseptic meningitis in Korea.

Objectives: We attempted to characterize nonpolio enteroviruses recovered from Korean patients with aseptic meningitis. Methods: We performed RT-PCR on the 5′-nontranslated region using clinical specimens. Infectious clinical isolates were amplified by infecting Vero cells with RT-PCR-positive clinical specimens. We then investigated the direct effect in primary neuronal cells or cardiomyocytes following virus infection. Results: Total 12 clinical isolates were subtypically analyzed by both RT-PCR/sequencing comparison of the VP-1 region and neutralization assay. 43-2, 43-2S, 57 and 58 were found to be coxsackievirus B1 (CVB1), 312 to be CVB5, 14-2S and 327 to be echovirus 6, 165 to be echovirus 9, 337 to be echovirus 11, and 270 to be echovirus 30. All the clinical isolates tested showed profound cytotoxicity to various degrees in the primary neuronal cells within 24 h postinfection at 10 MOI. By contrast, a significant cytopathic effect was observed in the primary cardiomyocytes at 3–5 days postinfection at 50 MOI. Conclusions: The present study suggests that the clinical isolates recovered from Korean patients belonged to different CVB or echovirus serotypes and that these viruses showed diversities in their virulence in primary neuronal cells and cardiomyocytes.