Zahide Cavdar

The Effects of α-Lipoic Acid against Testicular Ischemia-Reperfusion Injury in Rats

Testicular torsion is one of the urologic emergencies occurring frequently in neonatal and adolescent period. Testis is sensitive to ischemia-reperfusion injury, and, therefore, ischemia and consecutive reperfusion cause an enhanced formation of reactive oxygen species that result in testicular cell damage and apoptosis. α-lipoic acid is a free radical scavenger and a biological antioxidant. It is widely used in the prevention of oxidative stress and cellular damage. We aimed to investigate the protective effect of α-lipoic acid on testicular damage in rats subjected to testicular ischemia-reperfusion injury. 35 rats were randomly divided into 5 groups: control, sham operated, ischemia, ischemia-reperfusion, and ischemia-reperfusion +lipoic acid groups, 2 h torsion and 2 h detorsion of the testis were performed. Testicular cell damage was examined by H-E staining. TUNEL and active caspase-3 immunostaining were used to detect germ cell apoptosis. GPx , SOD activity, and MDA levels were evaluated. Histological evaluation showed that α-lipoic acid pretreatment reduced testicular cell damage and decreased TUNEL and caspase-3-positive cells. Additionally, α-lipoic acid administration decreased the GPx and SOD activity and increased the MDA levels. The present results suggest that LA is a potentially beneficial agent in protecting testicular I/R in rats.

TNF-related apoptosis-inducing ligand level in Alzheimer's disease.

In the present study, we determined the significance of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in Alzheimer’s disease (AD). We characterized the expression of TRAIL protein in the cerebrospinal fluid (CSF) and serum with ELISA and TRAIL mRNA in the peripheral blood mononuclear cells (PBMCs) with real-time PCR in 22 patients with AD and 20 control cases. We could not find TRAIL protein in the CSF samples. The concentration of TRAIL protein in sera from patients with AD was not different from controls. However, there was an inverse correlation between serum TRAIL levels and Mini-Mental State Examination scores in AD patients. Also we did not find significant difference in TRAIL mRNA in the PBMCs of patients with AD when compared with control group. Our data indicate that TRAIL serum level decreases in the late stage of disease.

Pioglitazone Reduces Peritoneal Fibrosis via Inhibition of TGF-β, MMP-2, and MMP-9 in a Model of Encapsulating Peritoneal Sclerosis

Abstract Objective: Matrix metalloproteinases (MMPs) and transforming growth factor beta (TGF-β) were increased in peritoneal dialysis patients with encapsulating peritoneal sclerosis (EPS) and in chlorhexidine gluconate (CG)-induced peritoneal sclerosing animal models. Peroxisome proliferator-activated receptors (PPARs) are the major regulators of key metabolic pathways of various inflammatory responses in fibrosing processes in most tissues. The objective of this study was to investigate the effect of pioglitazone (Pio), a synthetic PPAR-γ ligand, on the development of peritoneal fibrosis in CG-induced EPS rats. Methods: Thirty-two Wistar albino rats were intraperitoneally injected with saline (C group n = 8) or with CG (1.5 mL/100 g; CG group, n = 8). Pio (30 mg/kg/day) was administered orally to another group of CG injected rats (the CG + Pio group, n = 8) and to another control group (Pio group, n = 8) from initiation to the end of this study. After 14 days of Pio administration, the rats were killed and the parietal and visceral peritoneum were harvested. TGF-β, MMP-2, MMP-9, tissue inhibitor of metalloproteinases (TIMP)-1, and TIMP-2 activity assays and a morphological examination of the peritoneal tissues were performed. Results: Pio significantly inhibited thickening of the submesothelial layer, fibrosis, and inflammation in the peritoneum. It also prevented increases in pro-MMP-2, pro-MMP-9, TIMP-1, and TGF-β activities. Conclusion: Pio, via MMP and TGF-β inhibition, may lessen accumulation of peritoneal extracellular matrix and fibrosis to some extent in an EPS model and might be a new approach to the amelioration of EPS.

Effect of Intravenous Iron Sucrose on Oxidative Stress in Peritoneal Dialysis Patients

Aim. Intravenous iron therapy is an accepted treatment for patients receiving hemodialysis and continuous ambulatory peritoneal dialysis (CAPD). Studies have found enhanced oxidative stress in hemodialysis patients receiving intravenous iron, but there are no clinical data for CAPD patients. The aim of the current study was to investigate the effect of 100 mg of intravenous iron-sucrose on the erythrocyte (RBC) antioxidant enzymes (namely, superoxide dismutase [SOD], catalase [CAT], and glutathione peroxidase [GSHPx]) and plasma malondialdehyde (MDA), an oxidant molecule, in CAPD patients. Methods. Twelve CAPD patients receiving maintenance intravenous iron-sucrose were recruited. After a 12-hour fast, blood samples were taken for hemoglobin, iron, ferritin, and high-sensitivity C-reactive protein (hsCRP), and for baseline activities of erythrocyte antioxidant enzymes (i.e., SOD, CAT, GSHPx) and the plasma oxidant molecule, MDA. 100 mg iron-sucrose was infused over 30 minutes. Blood samples taken during (i.e., 15 minutes after commencement of infusion) and after (i.e., at 30 minutes, 60 minutes, and 6 hours after commencement) the infusion were taken for measurement of plasma iron, ferritin, TSAT, RBC SOD, CAT, GSHPx, and plasma MDA. Results. Plasma iron and transferrin saturation elevated significantly during infusion (p < 0.05). There was no significant change in erythrocyte SOD, CAT, GSHPx, or in MDA activities. There was a reduction of GSHPx activity at the 30th minute (from 153.69 ± 66.69 to 123.68 ± 25.50 mU/mL), but it was not statistically significant. The patients were grouped according to baseline ferritin (100–400 and 400–800 ng/mL); 60th-minute MDA was significantly higher in the latter group (p < 0.05). There was no correlation between hsCRP and oxidant-antioxidant balance. No correlation was noted between RBC antioxidant enzymes or plasma oxidant molecule and ferritin levels. Conclusion. There are no acute deteriorating effects from a 100 mg of intravenous iron-sucrose in CAPD patients with optimal iron stores. This dose may be applied safely in CAPD patients.

The effects of alpha-lipoic acid on MMP-2 and MMP-9 activities in a rat renal ischemia and re-perfusion model

Abstract Matrix metalloproteinases (MMPs) are enzymes that are responsible for degradation of extracellular matrix (ECM); they are involved in the pathogenesis of ischemia-re-perfusion (I-R) injury. We investigated the possible preventive effect of alpha-lipoic acid (LA) in a renal I-R injury model in rats by assessing its reducing effect on the expression and activation of MMP-2 and MMP-9 induced by I-R. Rats were assigned to four groups: control, sham-operated, I-R (saline, i.p.) and I-R+ LA (100 mg/kg, i.p.). After a right nephrectomy, I-R was induced by clamping the left renal pedicle for 1 h, followed by 6 h re-perfusion. In the sham group, a right nephrectomy was performed and left renal pedicles were dissected without clamping and the entire left kidney was excised after 6 h. LA pretreatment was started 30 min prior to induction of ischemia. Injury to tubules was evaluated using light and electron microscopy. The expressions of MMP-2 and MMP-9 were determined by immunohistochemistry and their activities were analyzed by gelatin zymography. Serum creatinine was measured using a quantitative kit based on the Jaffe colorimetric technique. Malondialdehyde (MDA) and glutathione (GSH) were analyzed using high performance liquid chromatography. Tissue inhibitor of metalloproteinase (TIMP)-2 and TIMP-1 were assessed using enzyme-linked immunosorbent assay (ELISA). I-R caused tubular dilatation and brush border loss. LA decreased both renal dysfunction and abnormal levels of MDA and GSH during I-R. Moreover, LA decreased significantly both MMP-2 and MMP-9 expressions and activations during I-R. TIMP-1 and TIMP-2 levels were increased significantly by LA administration. LA modulated increased MMP-2 and MMP-9 activities and decreased TIMP-1 and TIMP-2 levels during renal I-R.

Decrease in cell proliferation by an matrix metalloproteinase inhibitor, doxycycline, in a model of immune-complex nephritis

Aim:  Renal expression of matrix metalloproteinases (MMP) and tissue inhibitors of MMP (TIMP) contribute to the development of tubulointerstitial fibrosis characteristic of progressive forms of primary glomerulonephritis (GN).

Resveratrol Reduces Matrix Metalloproteinase-2 Activity Induced by Oxygen-Glucose Deprivation and Reoxygenation in Human Cerebral Microvascular Endothelial Cells

The main pathophysiology in cerebral ischemia is the structural alteration in the neurovascular unit, coinciding with neurovascular matrix degradation. Among the human matrix metalloproteinases (MMPs), MMP-2 and -9, known as gelatinases, are the key enzymes for degrading type IV collagen, which is the major component of the basal membrane that surrounds the cerebral blood vessel. In the present study, we investigated the effects of resveratrol on cytotoxicity, reactive oxygen species (ROS), and gelatinases (MMP-2 and -9) in human cerebral microvascular endothelial cells exposed to 6 hours of oxygen-glucose deprivation and a subsequent 24 hours of reoxygenation with glucose (OGD/R), to mimic ischemia/reperfusion in vivo. Lactate dehydrogenase increased significantly, in comparison to that in the normoxia group. ROS was markedly increased in the OGD/R group, compared to normoxia. Correspondingly, ROS was significantly reduced with 50 μM of resveratrol. The proMMP-2 activity in the OGD/R group showed a statistically significant increase from the control cells. Resveratrol preconditioning decreased significantly the proMMP-2 in the cells exposed to OGD/R in comparison to that in the OGD/R group. Our results indicate that resveratrol regulates MMP-2 activity induced by OGD/R via its antioxidant effect, implying a possible mechanism related to the neuroprotective effect of resveratrol.

The effect of renal replacement therapies on serum gastrointestinal system hormones.

Background. The kidney is a major site for the inactivation, degradation, and clearance of a variety of peptide hormones. It has been shown that the uremia increases or decreases gastrointestinal system (GIS) hormones. Moreover, studies investigating the serum GIS hormones levels in chronic renal failure (CRF) were conducted mainly in a particular period of the renal replacement therapy, and the changes caused by continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD) could not be fully demonstrated. In this study, we investigated the effect of CAPD and HD on serum GIS hormones (amylase, lipase, trypsinogen, and gastrin) levels in CRF patients who were diagnosed for the first time. Methods. Serum amylase, lipase, trypsinogen, and gastrin levels were measured in 36 patients who were just diagnosed with CRF, 22 patients with CAPD and 14 patients with HD. GIS hormones of these patients were measured before treatment and three months from the beginning of CAPD and HD treatment. As the control group, 20 normal healthy cases with well-matched age and gender were used. Results. The mean serum amylase, lipase, secretin, and gastrin levels were found meaningfully decreased according to the beginning values at third months of the CAPD and HD treatment. However, they were higher than control group. Conclusion. In patients receiving CAPD or HD as renal replacement therapy, GIS hormone levels were found to be lower, albeit higher than the healthy control group.

PRETREATMENT WITH NEBIVOLOL ATTENUATES LEVEL AND EXPRESSION OF MATRIX METALLOPROTEINASES IN A RAT MODEL OF RENAL ISCHEMIA-REPERFUSION INJURY.

Matrix metalloproteinases (MMPs) are zinc‐containing proteinases that are involved in the degradation of extracellular matrix (ECM) and a number of cell surface proteins in order to maintain tissue homeostasis. They are involved in pathogenesis of several ischaemic organ injuries. In the present study, we aimed to determine the expression and level of MMP‐2 and MMP‐9 in renal ischaemia–reperfusion injury (IRI) model and the potential beneficial effect of nebivolol, a β1‐adrenergic receptor blocker, on both MMP‐2 and ‐9 level and expression and tubular injury caused by IRI.

Special‐study modules in a problem‐based learning medical curriculum: An innovative laboratory research practice suppporting introduction to research methodology in the undergraduate curriculum

We describe the organization of wet‐lab special‐study modules (SSMs) in the Central Research Laboratory of Dokuz Eylül Medical School, Izmir, Turkey with the aim of discussing the scientific, laboratory, and pedagogical aspects of this educational activity. A general introduction to the planning and functioning of these SSMs is given, along with specific examples. The wet‐lab SSMs incorporate several innovative pedagogies: problem‐based learning, research‐based learning, practical laboratory education, team‐based learning, and project‐based learning. Oral and written evaluations show that the students find this activity rewarding. The wet‐lab SSM model applied in the Research‐Lab of Dokuz Eylül School of Medicine represents a format which is effective in training the students in research methodology, practical laboratory work, and independent learning. Biochemistry and Molecular Biology Education Vol. 39, No. 1, pp. 47–55, 2011