Biomedical subjects

Chul Woo Yang

Publications and source records attributed to Chul Woo Yang.

48 records · Page 3Linked to original sources

PubMed2002

Investigation of the factors influencing the release rates of cyclosporin A-loaded micro- and nanoparticles prepared by high-pressure homogenizer.

An oil-in-water solvent evaporation method was used to prepare cyclosporin A (CyA)-loaded particles varying in size (nanoparticles, 'small-sized' microparticles, 'large-sized' microparticles), polymer compositions [poly(D,L-lactide-co-glycolic acid) (PLGA) 50/50, PLGA 85/15, poly(D,L-lactic acid) (PLA)] and additive fatty acid ester (ethyl myristate; EM). The particles were characterized for drug loading and entrapment efficiency by high-performance liquid chromatography, particle size by dynamic light scattering and surface morphology by scanning electron microscopy (SEM). In vitro release kinetics were studied using a modified dialysis method. The results showed drug loadings ranging from 6.48 to 9.01% with high encapsulation efficiency (71.2-98.9%). SEM studies showed discrete and spherical particles with smooth surfaces, whereas rather gross surface defects resulted from the incorporation of EM as an additive. The release profiles of various formulations approximated zero-order release kinetics in the first 3 weeks with a negligible initial burst. In general, the smaller the particle size and the higher the glycolic acid content in the copolymer, the faster the release of CyA. The effect of EM on the release profile appeared to be rather complex since an increased release rate was observed from EM containing PLGA 50/50 particles, whereas the incorporation of EM into the PLGA 85/15 and PLA particles led to a decreased release rate. Further investigation needs to be performed to elucidate the reason why EM influences the CyA release differently depending on the particle size and polymer type.

Cyclosporine↗

PubMed2002

Reversibility of chronic cyclosporine nephropathy in rats after withdrawal of cyclosporine.

Renal interstitial inflammation is an important factor in the pathogenesis of chronic cyclosporin A (CsA) nephropathy. We studied the expression of the chemoattractant osteopontin (OPN) and the relationship between OPN expression and tubulointerstitial injury in a rat model of chronic CsA nephropathy. Chronic CsA nephropathy was induced in Sprague-Dawley rats by administering CsA (15 mg/kg sc) for 5 wk and then withdrawing it for 5 or 10 wk. Renal function, histopathology (arteriolopathy, ED-1-positive cells, and tubulointerstitial fibrosis), renin-angiotensin system (RAS) activity, and OPN expression were observed during the follow-up period. Renal function deteriorated in CsA-treated rats, with the development of typical histopathology and activation of RAS. After CsA withdrawal, these parameters were significantly reversed (all P < 0.05). The upregulation of OPN mRNA and protein expression seen in CsA-treated rat kidneys was decreased 5 wk after CsA withdrawal and was further decreased after 10 wk. Of note, OPN mRNA expression correlated with the number of infiltrating macrophage (r = 0.651, P < 0.01) and tubulointerstitial fibrosis (r = 0.729, P < 0.01). These findings suggest that OPN expression and macrophage infiltration decrease after long-term CsA withdrawal in rats with established chronic CsA nephropathy, and this is closely associated with recovery from renal injury.

Animals↗

PubMed2002

Comparisons of clinicopathological correlations between immediate and slow graft function in renal transplant recipients.

The functional recovery state of renal transplants can be divided into three types: immediate graft function (IGF), slow graft function (SGF) and delayed graft function (DGF). In contrast to the well-known clinical outcomes for IGF and DGF, the pathological findings and clinical outcomes of SGF are undetermined. This study evaluated possible clinicopathological correlations in 237 patients with SGF compared with patients with IGF. IGF and SGF were defined by serum creatinine levels (IGF < 1.2 mg/day l; SGF: >/=1.2 mg/dL) at day 14 after renal transplantation. Graft biopsy was performed on this day, and pathological classification was performed using the Banff schema. The SGF group of patients (n = 121) showed higher rates of cadaver donors and male recipients than the IGF group (n = 116), but there were no significant differences in recipient or donor age, numbers of HLA mismatches, types of immunosuppressant or follow-up periods between two groups. The SGF group showed higher serum creatinine levels at discharge, and a higher incidence of acute rejection than the IGF group (24.8% vs. 8.6%, P < 0.05) and lower graft survival rates (1 year, 93.3% vs. 100%; 5 years, 85.4% vs. 98.6%, respectively; P < 0.05). The presence of acute rejection in the SGF patients indicated a significantly decreased 5-year survival rate compared with the IGF group. The SGF group of patients with borderline pathology had a higher incidence of acute rejection than the IGF group, and significant increases in the expression of mRNA for pro-apoptotic genes (Fas-ligand, granzyme B and perforin) compared with the IGF group. In conclusion, SGF represents the activated immune state and is associated with poor graft outcome. Anti-rejection treatment or modified immunosuppressive regimen may thus be indicated for patients with SGF.

Adult↗

PubMed2002

Expression of apoptosis-related genes in chronic cyclosporine nephrotoxicity in mice.

To define the mechanism of cyclosporine (CsA)-induced apoptosis, we investigated the expression of apoptosis-related genes in experimental chronic CsA nephrotoxicity. Mice on a low-salt (0.01%) diet were given vehicle (VH, olive oil, 1 mg/kg/day), or CsA (30 mg/kg/day), and sacrificed at 1 and 4 weeks. Apoptosis was detected with deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) stain, and the expressions of apoptosis-related genes were evaluated by reverse transcription-polymerase chain reaction, immunoblot or immunohistochemistry. The activity of caspase 1 and 3 was also evaluated. The CsA group showed increases in apoptotic cells compared with the VH group (54 +/- 41 vs. 3 +/- 3, p < 0.05), and the number of apoptotic cells correlated well with interstitial fibrosis scores (r = 0.83, p < 0.01). The CsA group showed a significant increase in Fas-ligand mRNA (0.20 vs. 0.02 amol/microgram total RNA, p < 0.05) and Fas protein expression (146% vs. 95%, p < 0.05), compared with the VH group. The CsA group showed significant increases in ICE mRNA (0.21 vs. 0.03 amol/microgram total RNA at 4 weeks, p < 0.05) and CPP32 mRNA (0.18 vs. 0.03 amol/microgram total RNA at 4 weeks, p < 0.05), compared with the VH group. The enzymatic activity of ICE (16.6 vs. 7.9 rho mol/microgram/h, p < 0.05) and CPP32 protease (15.6 vs. 2.7 rho mol/microgram/h, p < 0.05) proteases were increased in the CsA group, compared with the VH group. The ratio between bax and bcl-2 protein increased significantly in the CsA group (5.3-fold), compared with the VH group. Levels of p53 protein also increased in the CsA group. Immunohistochemical detection of Fas, Fas-ligand, ICE and CPP32 revealed strong immunoreactivity in renal tubular cells in areas of structural injury. These findings suggest that local activation of the apoptosis-related genes is associated with CsA-induced apoptotic cell death.

Animals↗

PubMed2002

Cyclosporine withdrawal and mycophenolate mofetil treatment effects on the progression of chronic cyclosporine nephrotoxicity.

BACKGROUND: Recent clinical trials of mycophenolate mofetil (MMF) in chronic allograft nephropathy (CAN) demonstrated that the dose of cyclosporine A (CsA) is one of the critical factors in determining graft function in CAN, but the effect of MMF on chronic CsA nephropathy is undetermined. We undertook this study to evaluate the effect of MMF on CsA-induced nephrotoxicity in an animal model of chronic CsA nephropathy. METHODS: In the first experiment, Sprague-Dawley rats on a low-salt diet were treated with CsA (7.5 mg/kg per day) for 10 weeks, or were treated with CsA for five weeks and then MMF (20 mg/kg per day) was administered five weeks later. In the second experiment, rats were treated with CsA for five weeks, and CsA was then withdrawn for five weeks with or without MMF treatment. Renal function, histologic parameters (tubulointerstitial fibrosis, arteriolopathy, ED-1-positive cells, renin-positive glomeruli, TUNEL-positive cells) and the expression of osteopontin and transforming growth factor (TGF)-beta1 mRNA expressions were compared for different treatment groups. RESULTS: CsA-treated rats showed decreased renal function and increased histologic parameters compared with the vehicle (VH)-treated rats. The addition of MMF did not improve these parameters compared with the CsA-treated rats. With CsA withdrawal, renal function and histologic parameters were significantly improved compared with the CsA-treated rats, and MMF treatment after CsA withdrawal further improved the histologic parameters. At the molecular level, the addition of MMF did not decrease the expression of osteopontin and transforming growth factor-beta1 (TGF-beta1) mRNAs, which were increased in the CsA-treated rat kidney. With CsA withdrawal, the expression of both mRNAs was significantly decreased compared with the CsA group, and a further decrease was observed with MMF treatment after CsA was withdrawn. CONCLUSION: The combined treatment of CsA and MMF does not prevent the development of chronic CsA nephrotoxicity, but MMF treatment after CsA withdrawal does improve chronic CsA nephrotoxicity. This finding provides a rationale for MMF treatment in chronic CsA nephrotoxicity.

Animals↗

PubMed2002

Colchicine decreases apoptotic cell death in chronic cyclosporine nephrotoxicity.

Colchicine has been shown to prevent kidney injury in chronic cyclosporine nephrotoxicity; however, the mechanisms of its action are undetermined. The purpose of this study was to clarify whether colchicine prevents cyclosporine-induced kidney injury by decreasing kidney-cell apoptosis. We also sought to determine whether such an antiapoptotic effect was related to Bcl-2/Bax protein and caspase3 activity. Adult male Sprague-Dawley rats kept on a salt-depleted diet (0.05% sodium) were treated daily for 28 days with cyclosporine (15 mg/kg in 1 mL/kg olive-oil vehicle), colchicine (30 microg/kg in 100% ethanol, diluted with sterile saline solution to a final concentration of 30 microg/mL), or both cyclosporine and colchicine. Kidney function, histomorphologic findings, in situ terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate-biotin nick end-labeling assay, expressions of Bcl-2 and Bax proteins, and caspase-3 enzymatic activity were compared for the different treatment groups. Compared with the vehicle-treated rats, rats given cyclosporine showed a decline in creatinine clearance rate, an increase in serum creatinine concentration, tubulointerstitial fibrosis, and an increase in the number of apoptotic cells (all P <.01). Concomitant administration of colchicine significantly reversed all the above parameters (all P <.05). The decreased expression of Bcl-2 and the ratio of Bcl-2 to Bax protein seen in cyclosporine-treated rat kidneys were significantly increased after colchicine treatment, accompanying a suppression of caspase-3 activity (P <.05). Furthermore, the decreased apoptotic cell death was closely correlated with improved renal tubulointerstitial fibrosis (r = 0.583, P <.05). These findings strongly suggest that a renoprotective effect of colchicine on cyclosporine-induced nephrotoxicity is coassociated with a decrease in apoptotic cells.

Animals↗

PubMed2002

Colchicine suppresses osteopontin expression and inflammatory cell infiltration in chronic cyclosporine nephrotoxicity.

BACKGROUND: Colchicine (Col) is beneficial to renal injury because of its anti-inflammatory effect, but its mechanism has yet to be elucidated. The present study was designed to evaluate the inhibitory effects of colchicine on osteopontin (OPN) expression and the macrophage accumulation in chronic cyclosporine (CsA) nephrotoxicity in rats. METHODS: Male adult Sprague-Dawley rats on a low salt diet (LSD, 0.05% sodium) were treated daily with Col (30 microg/kg), CsA (15 mg/kg), and both CsA and colchicine or vehicle (olive oil 1 ml/kg) for 4 weeks. The effects of colchicine on chronic CsA nephrotoxicity were evaluated by examining renal function, histopathology, and ED-1 positive cells. The expressions of OPN mRNA and protein were estimated respectively by Northern blot and immunohistochemistry. RESULTS: Compared with vehicle-treated rats, CsA-treated rats showed an increase in serum creatinine, a decline in creatinine clearance rate, and tubulointerstitial fibrosis (all p < 0.01). Concomitant administration of colchicine reversed all of the above parameters (all p < 0.01). Of note, the upregulated expression of osteopontin mRNA and protein seen in CsA-treated rats was significantly decreased after colchicine treatment. Furthermore, the expression of osteopontin mRNA was strongly correlated with the number of ED-1 positive cells (r = 0.712, p < 0.001) and the tubulointerstitial fibrosis score (r = 0.586, p = 0.007). CONCLUSION: Colchicine is capable of abrogating the upregulation of chemotactic OPN expression and macrophage influx, and this is associated with improved renal tubulointerstitial fibrosis in chronic CsA nephrotoxicity.

Animals↗

PubMed2002

Acute interstitial nephritis due to nicergoline (Sermion).

We report a case of acute interstitial nephritis (AIN) due to nicergoline (Sermion). A 50-year-old patient admitted to our hospital for fever and acute renal failure. Before admission, he had been taking nicergoline and bendazac lysine due to retinal vein occlusion at ophthalmologic department. Thereafter, he experienced intermittent fever and skin rash. On admission, clinical symptoms (i.e. arthralgia and fever) and laboratory findings (i.e. eosinophilia and renal failure) suggested AIN, and which was confirmed by pathologic findings on renal biopsy. A lymphocyte transformation test demonstrated a positive result against nicergoline. Treatment was consisted of withdrawal of nicergoline and intravenous methylprednisolone, and his renal function was completely recovered. To our knowledge, this is the first report of nicergoline-associated AIN.

Acute Disease↗

PubMed2002

Cyclosporine or FK506 decrease mature epidermal growth factor protein expression and renal tubular regeneration in rat kidneys with ischemia/reperfusion injury.

BACKGROUND: Epidermal growth factor (EGF) plays an important role in tubular regeneration in kidneys with ischemia/reperfusion (I/R) injury. This study was undertaken to evaluate the influence of cyclosporine A (CsA) or FK506 on mature EGF expression and tubular regeneration in rat kidneys with I/R injury. METHODS: Two separate studies were performed. First, the expression of EGF and tubular regeneration was observed in rat kidneys with I/R injury on days 1, 2, 3, 5, and 7. Second, the dose-dependent response of EGF expression and tubular regeneration to CsA (5, 10, and 20 mg/kg) or FK506 (0.25, 0.5, and 1.0 mg/kg) was observed in rat kidneys with I/R injury. I/R injury was induced by clamping both renal arteries for 45 min, and CsA or FK506 was injected just after release of vascular clamps. Rats were sacrificed on day 1 for evaluation of EGF expression, and on day 2 for evaluation of BudU-positive cells. Renal function, tubular injury score, EGF expression assessed by immunoblotting, levels of CsA and FK506 in whole blood, and immunostaining for BrdU was studied. RESULTS: EGF expression was maximal on day 1 (cortex, 29-fold; medulla, 31-fold compared with sham-operated controls), and renal tubular regeneration measured with the number of BrdU-positive cells was maximal on days 2 and 3 in kidney with I/R injury, and thereafter the level of EGF and the number of BrdU-positive cells decreased progressively. CsA or FK506 treatment to ischemic rat kidneys reduced the expression of EGF and the number of BrdU-positive cells in a dose-dependent manner. CONCLUSIONS: CsA or FK506 treatment delays recovery from acute tubular necrosis, and this may be associated with decreased EGF expression by CsA or FK506.

Animals↗

PubMed2002

Superior mesenteric artery syndrome due to an aortic aneurysm in a renal transplant recipient.

Superior mesenteric artery (SMA) syndrome is a rare disease in which the third portion of the duodenum is compressed by SMA. There are many causes leading to the SMA syndrome, however it's extremely rare that aortic aneurysm causes a SMA syndrome. We report a case of a successfully treated SMA syndrome due to an abdominal aortic aneurysm in a renal transplant recipient. The patient was a 52-yr-old woman with a thin stature (weight 40 kg, height 164 cm). She received a renal transplant 8 yr before, and had hypertension and abdominal aortic aneurysm. Her SMA syndrome developed in a prolonged supine position for the accidental rib fractures and was diagnosed by clinical and radiological findings. After a surgical correction (resection of an aneurysm and aortobiiliac bypass with an inverted Y graft), her symptoms relieved without deterioration of the graft function.

Aortic Aneurysm, Abdominal↗

PubMed2001

Upregulation of ciliary neurotrophic factor (CNTF) and CNTF receptor alpha in rat kidney with ischemia-reperfusion injury.

Ciliary neurotrophic factor (CNTF) is presumed to play a role as a survival factor in neuronal cells, but little is known about its role in the kidney. To investigate this, the expression of CNTF and CNTF receptor alpha (CNTFR alpha) was analyzed in the ischemic rat kidney. An ischemia/reperfusion (I/R) injury was induced by clamping both renal arteries for 45 min. Animals were killed at 1, 2, 3, 5, 7, 14, and 28 d after ischemia. The expression of CNTF and CNTFR alpha was monitored by reverse transcription-PCR, in situ hybridization, immunoblotting, immunohistochemistry, and electron microscopy. In sham-operated rat kidneys, CNTF expression was weak and limited to the descending thin limb of the loop of Henle. With I/R injury, CNTF mRNA and protein expressions were strikingly increased as compared with the sham-operated rat kidney, and the immunoreactivity of CNTF was mainly observed in the regenerating proximal tubules. The expression of CNTFR alpha mRNA was also increased after I/R injury, and its location and expression patterns were similar to the expression of CNTF. These findings suggest a possible role of CNTF as a growth factor during renal tubular repair processes after I/R injury and an autocrine or paracrine function of CNTF acting against CNTFR alpha.

Animals↗

PubMedDate not supplied

BK polyomavirus interstitial nephritis in a renal allograft recipient.

Human polyomavirus (PV) interstitial nephritis has recently been recognized as a cause of severe renal allograft dysfunction. It occurs in immunosuppressed patients after reactivation of the latent virus PV type BK (BK virus) in the renal epithelium. BK disease is defined as a morphologically manifest renal infection with cytopathic signs accompanied by varying degrees of interstitial inflammatory cell infiltrates and functional impairment. It is also identified by the presence of cells containing viral inclusion bodies (decoy cells) in the urine. The authors report a case of BK PV interstitial nephritis in a 36-year-old renal allograft recipient. Under light microscopy the chief diagnostic indicator was detection of intranuclear viral inclusions, which were found exclusively in tubular epithelial cells. Cells with viral changes were often enlarged with nuclear atypia and chromatin basophilia. Widespread interstitial plasma cell infiltrates associated with tubulitis were present. Intranuclear paracrystalline arrays of virus particles 35-38 nm in diameter were present as characteristic ultrastructural indicators. Urine samples revealed decoy cells with ground-glass-type intranuclear inclusions positive for BK virus by electron microscopy.

Adult↗