Hüray İşlekel

Evaluation of some antioxidant enzymes in lung carcinoma tissue

This investigation was effected to determine the levels of the two antioxidant enzymes, superoxide dismutase (SOD) (EC 1.15.1.1) and catalase (CAT) (EC 1.11.1.6) in lung cancerous tissues and to compare with normal lung tissue in order to evaluate the antioxidant status in lung cancer. Fifteen lung carcinoma tissue samples and the normal counterparts from the same cases were homogenized and the cytosols obtained by ultracentrifugation (100,000 x g). SOD was assayed using a modification of the indirect nitroblue tetrazolium assay method, while CAT was measured by a spectrophotometric method. The data obtained are as follows: 1.42 +/- 0.24 U/mg protein (means +/- SEM) of SOD in lung cancer and 3.13 +/- 0.51 U/mg protein in normal lung tissue and 33.53 +/- 6.09 U/mg protein of CAT in lung cancer and 71.33 +/- 14.38 in normal lung tissue. The differences were found to be significant at the level of P < 0.01 for both enzymes. These low levels of the antioxidant enzymes in lung cancerous tissues can lead to elevated levels of reactive oxygen metabolites, resulting in damage to the key subcellular structures such as DNA, cell membranes, and other vital cellular components.

Evaluation of lipid peroxidation, cathepsin L and acid phosphatase activities in experimental brain ischemia–reperfusion

This investigation was conducted in rat brain tissues to elucidate the free radical induced cellular and subcellular membrane injuries in two different depth of global ischemia. Global moderate (penumbral) ischemia was performed on rat brains by bilateral vertebral arteries cauterization and temporary occlusion of the bilateral carotid arteries. Global severe ischemia was produced by a neck tourniquet in addition to four vessel occlusion. Somatosensory evoked potentials (SSEPs) were used as a feed back parameter to monitor electrophysiologically the ischemia. At the end of ischemic insult (0 min reperfusion) or various reperfusion periods (20, 60 and 240 min), all rats were decapitated and brains were frozen in liquid nitrogen. The brain tissues were prepared for the determination of cathepsin L (CL) and acid phosphatase (AP) activities in the supernatant (cytosolic) fraction (SF) and the fraction enriched with lysosomes (FEL). Further the level of thiobarbituric acid reactive substances (TBARS) of lipid peroxidation was assessed by the spectrophotometric methods. Severe ischemia-reperfusion was accompanied by a significant increase in TBARS levels and the SF/FEL ratio for CL and AP activities compared to the sham operated group and the concurrent reperfusion groups of moderate ischemia (p<0.05). There were no significant differences between the sham operated and moderate ischemia-reperfusion groups for the same parameters. Our data clearly demonstrate that; in rat brain although severe ischemia-reperfusion causes lipid peroxidation in cellular membranes and redistribution of lysosomal enzymes from lysosomes to cytoplasm due to lysosomal membrane injury, there are no changes in lysosomal membrane stability in moderate ischemia-reperfusion.

Effects of trimetazidine on acetic acid-induced colitis in female Swiss rats.

Induction of colitis by acetic acid (A A) in the rat is widely used experimental model of inflammatory bowel disease (IBD) and ulcerations. AA as an irritant induces colitis involving infiltration of colonic mucosa with neutrophils and increased production of inflammatory mediators, such as hydrogen peroxide (H 2 O 2 ), nitric oxide (NO), myeloperoxidase activity (MPO), and tumor necrosis factor (TNF- f ). Trimetazidine (TMZ), an antianginal compound, was administered to investigate if its cytoprotective features in cardiac tissue are also effective in AA colitis where ischemic injury contributes to colitis. Administration of TMZ intraperitoneally improved the macroscopic and microscopic score alterations produced by AA. AA administration significantly elevated colonic MPO activity; however, treatment with TMZ significantly lowered this enzyme activity compared to AA. AA administration significantly enhanced superoxide dismutase (SOD) activities, except for AA + TMZ given rectally. TMZ treatment significantly lowered nitrate levels, but A A increased these levels. AA administration markedly lowered TNF- f levels, but TMZ treatment elevated these levels to control. These findings indicate that overproduction of NO may be involved in the immunosuppression observed during acute AA-induced rat colitis. In conclusion, TMZ treatment was more effective via the intraperitoneal than rectal route, and may be beneficial in therapy of colitis.

Breast milk jaundice correlates with high levels of epidermal growth factor.

Maternal milk plays an important role in breast milk jaundice (BMJ) development and is the major source of epidermal growth factor (EGF) for neonates. The aim of this study was to investigate whether there is a relationship between EGF levels in the infant serum and in the milk of nursing mothers and BMJ. Two groups were defined: study group (n = 30), newborns who were followed up for BMJ without any identifiable pathologic cause; control group, healthy newborns whose serum total bilirubin levels were <10 mg/dL. Milk and infant plasma samples were collected between the third and the fourth postpartum week. EGF concentrations in all of the samples were determined by using ELISA. The infants with BMJ had higher concentrations of EGF in the serum and in the breast milk compared with that of the infants without BMJ. The milk concentrations of EGF were significantly correlated with neonatal bilirubin and blood EGF concentrations. The degree of BMJ was associated with the increased levels of milk borne EGF. Although the exact mechanisms of the hyperbilirubinemic action of EGF are not completely known, the inhibition of gastric motility, increased absorption, and activation of bilirubin transport have been suggested as possible mechanisms.

Urinary Nitrite Excretion in Low Birth Weight Neonates with Systemic Inflammatory Response Syndrome

Increased nitric oxide (NO) levels are thought to play an important role in the pathophysiology of the systemic inflammatory response syndrome (SIRS) which is caused by disseminated vascular endothelial damage. Clinical studies have shown that urinary nitrite (NO2-) and nitrate (NO3-) excretions can be utilized as indexes of NO formation. The SIRS and NO relationship was investigated in 15 neonates with SIRS, gestational age 32.5 +/- 4.4 weeks and weight 1,737 +/- 753 g. The control group comprised 18 neonates with a gestational age of 32.8 +/- 3.5 weeks and a weight of 1,778 +/- 538 g. There was no significant difference in birth weights and gestational ages between the two groups (p > 0.05 and p > 0.05). The urinary nitrite levels obtained in the subjects were normalized for urinary creatinine concentrations. The mean urinary nitrite levels in the control group neonates were found to be 4.22 +/- 1.8 micromol/mmol creatinine on the 1st day, 4.09 +/- 2.28 on the 2nd, 3.62 +/- 1.6 on the 3rd, and 4.01 +/- 1.12 micromol/mmol creatinine on the 7th day. There were no statistically significant differences between these levels (p > 0.05). We determined urinary levels of nitrite in neonates in the study group within the first 24 h of SIRS symptoms and found these levels (18.35 +/- 11.16 micromol nitrite/mmol creatinine) to be elevated as compared with those of the control subjects on the 7th day of life (p < 0.0005). In conclusion, urinary nitrite excretion is significantly elevated in neonates with SIRS due to septic events, and these results suggest that NO might play a part in SIRS.

Effects of HRT on serum levels of IGF-I in postmenopausal women

OBJECTIVES It is thought that insulin-like growth factor-1 (IGF-I) stimulates bone formation. We aimed to determine the effects of oral and transdermal hormone replacement therapy (HRT) on serum IGF-I levels and to investigate the effects of basal IGF-I levels on the levels obtained at the end of the therapy. METHODS Sixty-six postmenopausal women were administered either oral (n=44) or transdermal (n=22) HRT for 6 months. Serum levels of IGF-I were determined before and after HRT in all subjects. Groups were divided into two subgroups according to the median value of serum IGF-I levels (basal IGF-I levels above or below the median value). The increase of IGF-I levels after HRT were calculated (%) for all women. Mean increases of subgroups were compared. Furthermore, study groups were divided into three subgroups according to the changing of IGF-I (increase>25%, between 25% increase and 25% decrease and decrease>25%). Mean basal IGF-I levels of these three subgroups were compared. RESULTS Mean serum levels of IGF-I before and after HRT were not significantly different in both oral and transdermal groups (P>0.05). Mean increases of IGF-I after HRT for the patients with low basal IGF-I levels, were 65% in oral and 77% in transdermal groups. However, mean increase of the patients with high basal IGF-I levels were -8 and -16% respectively. Moreover, mean level of basal IGF-I was significantly low in women who have more than a 25% increase after HRT (P<0.05). CONCLUSION HRT seems to significantly increase serum levels of IGF-I in postmenopausal women with low basal levels of IGF-I.

MMP-2 and MMP-9 Alteration in Response to Collaring in Rabbits: The Effects of Endothelin Receptor Antagonism

Matrix metalloproteinases (MMPs), and, in particular, gelatinases (MMP-2 and MMP-9), have been implicated in vascular cell proliferation and/or migration, contributing to intimal thickening, an essential stage in the development of atherosclerosis and restenosis following balloon angioplasty. Endothelin, a strong chemoatractant and mitogen, has been shown to promote smooth muscle cell proliferation and migration by activating MMPs via endothelin-A (ETA) receptors. The positioning of a soft silicon collar around the left carotid artery in rabbits results in intimal thickening. In this study, we investigate the possible role of gelatinases and the effect of a nonselective ETA/ETB receptor antagonist, TAK-044 (5 mg/kg body weight/day, subcutaneously [sc]), on these enzymes. Our results demonstrated that both MMP-2 and MMP-9 activities increased in response to collaring in placebo group, while treatment with TAK-044 significantly suppressed both gelatinase activities and proMMP-2 levels, and inhibited intimal thickening in collared arteries. These results suggest that either enhanced MMP expression or endothelin receptor antagonism may be involved in the formation of intimal thickening in this model.

Urinary N-acetyl-β-D-glucosaminidase activity in rabbits with experimental hypercalciuria

Abstract. Routinely used renal function tests remain normal in uncomplicated hypercalciuria. The aim of this study was to assess the value of N-acetyl-β-D-glucosaminidase (NAG), a sensitive marker of renal proximal tubular damage, in experimental hypercalciuria. Oral calcium providing 75 mg/kg per day elementary calcium and 20,000 IU/day vitamin D3 was administered for 15 days to 7 rabbits (Orytolagus cuniculus-New Zealand white) and 7 rabbits were given placebo as a control group. Serum calcium, phosphorus, and alkaline phosphatase, daily urinary calcium excretion and NAG/creatinine ratio were measured before and after drug administration. Kidneys were examined macroscopically and microscopically following the study period. Serum calcium, phosphorus and urinary calcium excretion increased, while alkaline phosphatase decreased significantly in response to drug treatment [10.8±1.5 vs. 12.2±1.3 mg/dl, 4.6±0.6 vs. 6.7±0.7 mg/dl, 22.3±8.3 vs. 46.8±22.5 mg/kg per day, and 138.0±57.1 vs. 70.1±33.1 IU/l, respectively (P <0.05)]. The NAG/creatinine ratio prior to the study (0.5±0.1 mU/mg) was significantly different from that after the study (5.4±1.5 mU/mg, P <0.01). In the control group, changes in serum and urinary parameters were not significant (P >0.05). The relationship between the urinary NAG/creatinine ratio and the daily urinary calcium excretion was statistically significant (r = 0.67, P <0.05). In the study group, nephrocalcinosis was present in all rabbits except 1 (85.7%), whereas none of the control group rabbits had nephrocalcinosis. In conclusion, in rabbits urinary NAG excretion increases significantly in nephrocalcinosis induced by hypercalciuria.

The role of endothelin receptor antagonism in collar‐induced intimal thickening and vascular reactivity changes in rabbits

Intimal thickening, due to smooth muscle cell migration and proliferation, is considered to be one of the major components of vascular proliferative disorders such as atherosclerosis and restenosis. One experimental model, resulting in intimal thickening in the rabbit, involves placing a silicon collar around the carotid artery, and is used in this study. Endothelin is known to act as a strong mitogen and to stimulate smooth muscle cell proliferation and migration. We investigated the contribution of endothelin to the development of collar‐induced intimal thickening and the effects of TAK‐044, (5mg kg−1 daily, s.c.), a non‐selective ETA/ETB receptor antagonist, on intimal thickening and vascular reactivity changes in the collared rabbit carotid artery. Endothelin levels and the intimal cross‐sectional area, as well as the ratio of intimal area to media (index), increased significantly in collared arteries as compared with those in sham‐operated arteries. TAK‐044 significantly inhibited intimal thickening and also decreased the index without affecting increased endothelin levels in collared arteries. Vascular reactivity changes in response to collaring produced predictable effects, such as decreased contractile responses to vasoconstrictor agents and increased sensitivity to serotonin (5‐hydroxytrypt‐amine, 5‐HT). In terms of contractile responses in this model, TAK‐044, in particular, did not affect collar‐induced vascular reactivity changes. These results suggest that endothelin may be involved in the pathogenesis of collar‐induced intimal thickening. As an endothelin receptor antagonist, TAK‐044 may potentially be beneficial in the treatment of atherosclerosis.

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.