S S Kang

Gyeongsang National University, Shinshū, South Gyeongsang, South Korea

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Publications (37)101.43 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The study aimed to evaluate the efficacy of recombinant adenovirus expressing αA-crystallin (Ad-αAc-Gfp) in reducing pericyte loss within retinal vasculature in early diabetes. Diabetes was induced by streptozotocin injection into C57BL/6 mice. Ad-αAc-Gfp was delivered by intravitreous injection to the right eyes of mice 2 weeks before induction of diabetes. Vascular leakage was determined by fluorescent angiography, Evans Blue leakage assay and leucocyte adhesion test. Production of αA-crystallin was analysed by immunoblotting and double immunostaining and pericyte loss was analysed by pericyte count. Vessel leakage and pericyte loss were observed in the streptozotocin-induced diabetic retina. Decreased abundance of αA-crystallin in retinas 2 and 6 months after the induction of diabetes was confirmed by two-dimensional electrophoretic analysis, immunoblotting and RT-PCR. Double immunofluorescence staining for αA-crystallin and NG2 chondroitin sulphate proteoglycan revealed that αA-crystallin was predominantly produced in the retinal pericyte and that the number of αA-crystallin-producing pericytes decreased in the diabetic retina. Retinal infection with Ad-αAc-Gfp led to decreased pericyte loss and vascular leakage compared with control. Intravitreal delivery of Ad-αAc-Gfp protects against vascular leakage in the streptozotocin-induced model of diabetes. This effect is associated with the inhibition of diabetic retinal pericyte loss in early diabetes, suggesting that αA-crystallin has a role in preventing the pathogenesis of early diabetic retinopathy.
    Diabetologia 07/2012; 55(10):2835-44. · 6.49 Impact Factor
  • Circulation Research - CIRC RES. 01/2009; 105(1):16-24.
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    ABSTRACT: The present study was undertaken to determine how tumour necrosis factor-alpha (TNF-alpha) elicits the inhibition of glucose-stimulated insulin secretion (GSIS) in rat insulinoma cells (INS)-1 beta-cells. TNF-alpha pretreatment did not change the expression levels of insulin, PDX-1, glucose transporter 2, glucokinase, K(ATP) channels, Ca(2)(+) channels, and exocytotic molecules and, furthermore, did not reduce the glucose-stimulated ATP level. On the other hand, TNF-alpha reduced the glucose-stimulated influx of Ca(2)(+). The TNF-alpha treatment was thought to activate c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and NF-kappaB inflammatory signals, since TNF-alpha increased phospho-JNK and phospho-p38 and reduced I kappaB levels. Inhibitors of these signaling pathways prevented the TNF-alpha-induced reduction of the Ca(2)(+) influx and GSIS. Overexpression of MEKK3, a possible mediator from the TNF-alpha receptor to the JNK/p38 and NK-kappaB signaling cascade, increased the levels of phospho-JNK, phospho-p38, and NF-kappaB, and reduced the glucose-stimulated Ca(2)(+) influx and GSIS. The reduction of the Ca(2)(+) influx and GSIS in MEKK3-overexpressing INS-1 cells was also prevented by inhibitors of JNK, p38, and NF-kappaB. These data demonstrate that TNF-alpha inhibits GSIS by reducing the glucose-stimulated Ca(2)(+) influx, possibly through the activation of JNK and p38 MAPK and NF-kappaB inflammatory signals. Thus, our findings suggest that the activation of stress and inflammatory signals can contribute to the inhibition of GSIS in the development of diabetes.
    Journal of Endocrinology 01/2008; 198(3):549-560. · 4.06 Impact Factor
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    ABSTRACT: We investigated the relationship between phosphorylation of alphaB-crystallin (αBC) and retinal apoptosis in type 2 diabetes. The retinas of male Otsuka Long–Evans Tokushima fatty (OLETF) rats at 24 and 35 weeks were used as an animal model for type 2 diabetes and sex- and age-matched Long–Evans Tokushima Otsuka (LETO) rats were used as controls. In the retinas of 35-week OLETF rats, the interaction between αBC and protein kinase C delta (PKC δ) among the PKC isozymes, αBC phosphorylation at Ser45 (S45p-αBC), TUNEL-positive apoptotic ganglion cells, several apoptotic signs, and co-localization of S45p-αBC and TUNEL significantly increased as compared with other groups while the αBC–Bax interaction greatly decreased. These changes were abolished by rottlerin treatment, a highly specific PKC δ inhibitor. These results suggest that PKC δ is involved in regulation of anti-apoptotic function of αBC in the retina of type 2 diabetes.
    Neurobiology of Disease 01/2008; · 5.62 Impact Factor
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    ABSTRACT: Streptozotocin (STZ) has been commonly used to induce in vivo and in vitro hyperglycemic diabetes and its toxicity leads to inflammation and vascular injury. Triamcinolone acetonide (TA), as an anti-angiogenic/anti-inflammatory drug, is clinically used to improve the visual acuity in neovascular and edematous ocular diseases. The aim of this study was to investigate the effect of TA on early inflammation and vascular leakage in the retina of STZ-induced hyperglycemic rats. Hyperglycemia was induced in 8-week-old male Sprague–Dawley (SD) rats by a single intraperitoneal injection of STZ (65 mg/kg); only rats with blood glucose levels > 13.9 mmol/l 1 day after STZ injection were included in STZ-hyperglycemic group. Sex- and age-matched SD rats injected with buffer were used as the control group. One day before STZ and buffer injection, 2 μl TA (4 mg/ml in saline) and 2 μl saline were intravitreal-injected into the right and the left eyes of rats, respectively. Retinal vascular leakage was measured using the Evans-blue method. Changes in pro-inflammatory target genes, such as tumor necrotic factor (TNF)-α, intracellular adhesion molecule (ICAM)-1, and vascular endothelial growth factor (VEGF) were assessed by immunoblottings, immunostaining, and ELISA analyses. Vascular hyperleakage and up-regulation of most pro-inflammatory genes peaked within a few days after STZ injection and had recovered. However, these changes were blocked by TA pretreatment. Our data suggest that TA controls STZ-induced early vascular leakage and temporary pro-inflammatory signals in the rat retina.
    Life Sciences 09/2007; · 2.56 Impact Factor
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    ABSTRACT: We examined the effect of triamcinolone acetonide (TA), a corticosteroid, on the relationship between vascular pathophysiology and vascular endothelial growth factor (VEGF) activation in the retina of a rat model of oxygen-induced retinopathy (OIR). OIR was induced by exposure of hyperoxia (80% oxygen) to Sprague-Dawley (SD) rats from P2 to P14 and then returned to normoxic conditions. TA was intravitreal-injected once into the right eye of OIR rats at P15. Effects of TA on vascular pathophysiology or changes of various genes in response to hypoxia and/or proinflammation under hypoxic retina were assessed by the Evans-blue method, fluorescein isothiocyanate-dextran (FITC-D) infusion, immunoblotting, and ELIZA. TA not only reduced retinal neovascularization and vascular leakage in the OIR-rat retina, but also blocked the induction of hypoxia-response proinflammatory genes before it negatively controlled VEGF activation. These findings suggest a potential that TA suppresses retinal neovascular pathophysiology via proinflammation-mediated activation of VEGF during hypoxia.
    Neurobiology of Disease 07/2007; 26(3):569-76. · 5.62 Impact Factor
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    ABSTRACT: We present our experience with the neuronavigation system as used for surgery of distal anterior cerebral artery (DACA) aneurysm. Between 2001 and 2004, 12 patients with a DACA aneurysm were consecutively treated with direct clipping assisted by the neuronavigation system. We used the BrainLAB Vector Vision neuronavigation system (BrainLAB, Heimstetten, Germany). Seven out of 12 patients presented with subarachnoid hemorrhage. Aneurysms were located at distal A2 in 10 patients and distal A3 in two patients. The size of the aneurysms ranged from 3-10 mm. There were no procedure-related complications or technical problems during application of the neuronavigation system. The registration accuracy ranged from 0.5-1.5 mm (mean: 0.88 mm). The neuronavigation system provided real-time presentation of the DACA and the aneurysm, and allowed for identification of the DACA aneurysm in all patients. No surgical complications developed, and all 12 patients had a good recovery after direct clipping. Although current neuronavigation systems are not available for all intracranial aneurysms, we believe that the DACA aneurysm is a good candidate for its use. The additional benefits of a small craniotomy and precise intraoperative orientation during surgery result in a minimally invasive aneurysm procedure.
    min - Minimally Invasive Neurosurgery 07/2007; 50(3):140-4. · 0.62 Impact Factor
  • Materials Science Forum - MATER SCI FORUM. 01/2007;
  • Korean Journal of Materials Research 01/2006; 16(9):584-591.
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    ABSTRACT: The present study aimed to investigate the expression levels of and the relationship between 14-3-3 zeta and protein kinase C (PKC) in the retina of early diabetes. Changes in the expression levels of, and interaction between, 14-3-3 zeta and PKC were investigated by Northern and Western blot analyses, immunoprecipitation and double immunostaining in the retina of diabetic rats after 6 weeks of diabetes. PKC activity was examined using a PKC assay. In the diabetic retina, the molecular levels of 14-3-3 zeta were reduced, while those of PKC beta and zeta were increased. Direct interaction between 14-3-3 zeta and PKC was markedly decreased in the retina after 6 weeks of diabetes, while PKC activity was increased. These findings show that a reduction in 14-3-3 zeta can induce PKC activation, suggesting that this is a main cause of visual dysfunction in the retina during diabetes.
    Diabetologia 08/2005; 48(7):1411-5. · 6.49 Impact Factor
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    ABSTRACT: We have applied the neuronavigation system to endoscopic biopsy and third ventriculostomy in the management of patients with a pineal tumor with hydrocephalus. With the guidance of neuronavigation, the two optimal sites of burr hole and trajectories were planned preoperatively, and the advancing endoscopic device was monitored in real time during the procedure. In our five patients, the diameters of the tumors were 2-3 cm, and the mean systemic accuracy of registration with neuronavigation was 1.2 mm. The biopsy and third ventriculostomy were performed successfully via the respective optimal burr hole and the trajectory determined using preoperative neuronavigation. There were no procedure-related complications, and none of the patients needed another procedure for CSF diversion during the follow-up periods. We present our technique which includes the application of the neuronavigation system to the biopsy and third ventriculostomy in pineal tumor with associated hydrocephalus. This technique can be performed using a simple rigid endoscope via the determined optimal entries and trajectories. The optimal preoperative planning and the intraoperative guidance by neuronavigation are thought to be able to give more chances to minimize the brain injury related to movements or deviation of endoscopic device.
    min - Minimally Invasive Neurosurgery 01/2005; 47(6):365-8. · 0.62 Impact Factor
  • Brain Research 06/2003; 976(1). · 2.88 Impact Factor
  • Epilepsy Research 01/2003; 53(1). · 2.24 Impact Factor
  • Journal of Korean Neurosurgical Society. 01/2002; 31(1):16-20.
  • J K Lee, J H Kim, J S Kim, T S Kim, S Jung, S H Kim, S S Kang, J H Lee
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    ABSTRACT: We report a rare case of cervical dermal sinus associated with a dermoid cyst in a 10-month-old infant, who presented with a 1-month history of motor weakness of the right upper extremity. Magnetic resonance imaging showed an intradural extramedullary dermoid cyst extending from C3 to C4, which was connected with the skin dimple along the sinus tract. Total excision of the dermoid cyst and the sinus tract with C3-5 laminectomy resulted in good functional recovery.
    Child s Nervous System 09/2001; 17(8):491-3. · 1.24 Impact Factor
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    J K Lee, J H Kim, J S Kim, T S Kim, S Jung, S H Kim, S S Kang, J H Lee
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    ABSTRACT: Amenorrhea is rarely presented as a manifestation of endocrinological disturbances in patients of chronic hydrocephalus. We describe two cases of secondary amenorrhea caused by hydrocephalus due to aqueductal stenosis. Two female patients of age 30 and 20 yr presented with amenorrhea and increasing headache. Magnetic resonance images revealed marked, noncommunicating hydrocephalus without any tumorous lesion. In one patient, emergent extraventricular drainage was necessary because of progressive neurological deterioration. Each patient underwent surgical intervention for the hydrocephalus-ventriculoperitoneal shunt and endoscopic third ventriculostomy. Both resumed normal menstruation continuing so far with further normal menstrual bleeding. These two cases and others reported in the literature indicated that the surgical intervention for hydrocephalus resolves amenorrhea in all the cases of amenorrhea due to hydrocephalus. The suspected role of the surgery is the correction of increased intracranial pressure, which is an important pathogenetic factor in the development of amenorrhea.
    Journal of Korean Medical Science 09/2001; 16(4):532-6. · 1.25 Impact Factor
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    ABSTRACT: Recent molecular studies indicate two different genetic pathways leading to the development of glioblastoma; final progression of astrocytoma and de novo formation. To define the mutual relationships of cytogenetic changes in the pathogenesis of glioblastoma, molecular histopathologic alterations of p53 and epidermal growth factor receptor (EGFR) were evaluated by single stranded conformational polymorphion, reverse transcriptase-polymerase chain reaction and immunohistochemical stains in 15 primary and 21 secondary glioblastomas. Mutations in p53 gene and positive immunoreactivity to p53 protein (DO1) were more prevalent in secondary glioblastomas than in primary glioblastomas. A correlation between p53 mutations and p53 immunopositivities in glioblastomas was observed in 83.3% of the cases. All cases with positive p53 immunoreactivities showed p53 mutations; however, 13.9% of glioblastomas with p53 immuno-positivities lacked the relevant mutations. EGFR amplifications were detected in 73.3% of primary glioblastomas and 9.5% of secondary glioblastomas (p<0.001). The concurrence of p53 mutation and EGFR amplification was revealed in only 2 out of 15 primary glioblastomas and none among the secondary glioblastomas. Immunoreactivities for EGFR were noted in 66.7% of primary glioblastomas and in 9.5% of secondary glioblastomas (p<0.001). A correlation between EGFR amplification and EGFR immunopositivity in glioblastomas was observed in 91.7% of the cases. These data indicate that EGFR amplification and p53 mutations are two independent genetic events in the development of glioblastomas.
    Journal of Korean Medical Science 08/2001; 16(4):481-8. · 1.25 Impact Factor
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    ABSTRACT: The protein melanotransferrin (p97) is associated with the brain lesions of Alzheimer's disease (AD) and is a potential marker of the disorder. We measured serum p97 concentrations in 211 subjects: 71 patients with AD, 56 patients with non-AD-type dementia, and 84 normal control subjects. Serum p97 concentrations were elevated 3- to 4-fold in AD (median 15.00 pg/microl, interquartile range 10.20-17.00 pg/microl) as compared to non AD dementia (2.85 pg/microl, 1.93-7.15 pg/microl) and normal controls (3.20 pg/microl, 2.55-3.95 pg/microl). The mean elevation was significant at 13.54 +/- 3.72 pg/microl, even in the 38 subjects with mild AD (CDR stage 0.5-1). Receiver operating characteristic analyses confirmed an optimal diagnostic threshold of 10.0 pg/microl, which yielded over-all accuracy of 0.882 to 0.915. Serum p97 is a candidate marker of AD, even in the early stage when clinical diagnosis is most uncertain.
    Neuropsychopharmacology 08/2001; 25(1):84-90. · 8.68 Impact Factor
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    ABSTRACT: Steroid hormones modulate a variety of physiological functions in the hypothalamus. We attempted to identify steroid-regulated genes in the rat preoptic area-anterior hypothalamus by comparing differentially expressed mRNAs. Adult female rats were ovariectomized and, 1 week later, a silastic capsule containing 17beta-oestradiol (180 microg/ml) was subcutaneously implanted. After 2 days, a single injection of progesterone (1 mg) was administered at 10.00 h and rats were killed at 17.00 h on the same day. Differential-display polymerase chain reaction followed by Northern blot analysis showed that 10 clones were differentially regulated. Using homology search in Genbank, three genes were identified as sodium, potassium-ATPase beta1, protein kinase C-binding Nell-homologue protein and evectin-1. Further characterization of 10 clones showed that the expression patterns were tissue-specific and differentially regulated during puberty. Among these, mRNAs for protein kinase C-binding Nell-homologue protein, evectin-1 and human CGI-118 protein-like gene were induced after vagina opening, and differentially expressed during the oestrous cycle. Taken together, several steroid-regulated genes identified in the present study may play an important role in regulating hypothalamic functions, including puberty and the oestrous cycle.
    Journal of Neuroendocrinology 07/2001; 13(6):531-9. · 3.51 Impact Factor
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    ABSTRACT: A 22-year-old woman with Cushing's syndrome, caused by an extremely rare suprasellar ectopic pituitary adenoma, is presented. Magnetic resonance imaging and computed tomography revealed a well-circumscribed mass in the right suprasellar region. Endocrinological tests showed elevated s-adrenocorticotropic hormone level and hypercortisolemia. The tumor was totally removed by right subfrontal approach. At the time of the operation, the tumor was in continuity with the distal pituitary stalk but not with the pituitary gland. The diaphragma sellae was intact. Histologic diagnosis of the tumor specimen was confirmed as a pituitary adenoma. After surgical removal of the tumor, continued improvement in the patient's laboratory results and disappearance of her endocrine symptoms strongly indicated the absence of adenoma cells in the pituitary gland or stalk. Six years post-surgery, there was no evidence of recurrence in the patient's clinical and laboratory examination. This tumor probably originated from aberrant anterior pituitary cells of the pituitary stalk.
    Pathology International 12/2000; 50(11):901-4. · 1.72 Impact Factor

Publication Stats

722 Citations
101.43 Total Impact Points

Institutions

  • 1999–2012
    • Gyeongsang National University
      • College of Veterinary Medicine
      Shinshū, South Gyeongsang, South Korea
  • 1998–2005
    • Chonnam National University Hospital
      Sŏul, Seoul, South Korea
  • 2001
    • Chungbuk National University
      • School of Science Education
      Chinsen, North Chungcheong, South Korea
    • Chonnam National University
      • Department of Neurosurgery
      Kwangju, Gwangju, South Korea
  • 1999–2001
    • Seoul National University
      • • Department of Biological Sciences
      • • College of Natural Sciences
      Seoul, Seoul, South Korea