Suna Omeroglu

Antioxidant and triglyceride-lowering effects of vitamin E associated with the prevention of abnormalities in the reactivity and morphology of aorta from streptozotocin-diabetic rats

In this study, we evaluated the effects of vitamin E on the vascular reactivity and structure of thoracic aorta from streptozotocin (STZ)-diabetic rats. Plasma glucose, cholesterol, and triglyceride concentrations in rats were increased markedly by STZ-diabetes. The thiobarbituric acid (TBA) reactivity level as an index of lipid peroxidation was higher in both plasma and aorta of STZ-diabetic rats compared with controls. The rings of thoracic aorta with or without endothelium were mounted in organ chambers for measurement of isometric tension and were contracted by a single dose (10-5 mol/L) and then cumulative doses of noradrenaline ([NA] 10(-9) to 10(-5) mol/L). Pretreatment with methylene blue (MB) or removal of the endothelium resulted in a similar degree of enhancement in NA-induced contraction of control rings. STZ-diabetes increased the fast and slow components of NA-induced contraction in all experiments. The maximal contractile response of aorta to NA was also augmented by STZ-diabetes, whereas the sensitivity (pD2) remained unaltered. STZ-diabetes resulted in significant increases in the maximum contractile response and sensitivity of aorta to KCl. STZ-diabetic rats showed a significant reduction in the percentage of endothelial response (PER). A group of diabetic rats was treated from the time of diabetes induction with a 0.5% dietary supplement of vitamin E. Vitamin E supplementation of STZ-diabetic rats eliminated accumulation of lipid peroxides and returned plasma triglycerides toward normal levels. Diabetes-induced abnormal contractility and endothelial dysfunction were significantly but not completely prevented by vitamin E treatment. The endothelium-independent relaxation response to sodium nitroprusside (SNP) was not affected by diabetes or vitamin E treatment. Electron microscopic examination of thoracic aorta revealed that normal tissue organization was disrupted in STZ-diabetic rats, and that vitamin E treatment can protect the morphological integrity of aorta against STZ-diabetes. The results suggest the following: (1) The increased triglycerides/lipid peroxides may be an important reason for morphological or functional disruption of endothelium and enhanced activation of contractile mechanisms of vascular smooth muscle in STZ-diabetic rats. Both contribute to an increased responsiveness of diabetic aorta to vasoconstrictor agents. (2) Vitamin E treatment of STZ-diabetic rats can prevent the development of abnormal contractility and structure and endothelial dysfunction in aorta. (3) The triglyceride- and/or lipid peroxidation-lowering effect of vitamin E may be crucial for the protective effect of this vitamin on the vasculature.

Pulse modulated 900 MHz radiation induces hypothyroidism and apoptosis in thyroid cells: A light, electron microscopy and immunohistochemical study

Purpose: In the present study we investigated the possible histopathological effects of pulse modulated Radiofrequency (RF) fields on the thyroid gland using light microscopy, electron microscopy and immunohistochemical methods. Materials and methods: Two months old male Wistar rats were exposed to a 900 MHz pulse-modulated RF radiation at a specific absorption rate (SAR) of 1.35 Watt/kg for 20 min/day for three weeks. The RF signals were pulse modulated by rectangular pulses with a repetition frequency of 217 Hz and a duty cycle of 1:8 (pulse width 0.576 ms). To assess thyroid endocrine disruption and estimate the degree of the pathology of the gland, we analysed structural alterations in follicular and colloidal diameters and areas, colloid content of the follicles, and height of the follicular epithelium. Apoptosis was confirmed by Transmission Electron Microscopy and assessing the activites of an initiator (caspase-9) and an effector (caspase-3) caspases that are important markers of cells undergoing apoptosis. Results: Morphological analyses revealed hypothyrophy of the gland in the 900 MHz RF exposure group. The results indicated that thyroid hormone secretion was inhibited by the RF radiation. In addition, we also observed formation of apoptotic bodies and increased caspase-3 and caspase-9 activities in thyroid cells of the rats that were exposed to modulated RF fields. Conclusion: The overall findings indicated that whole body exposure to pulse-modulated RF radiation that is similar to that emitted by global system for mobile communications (GSM) mobile phones can cause pathological changes in the thyroid gland by altering the gland structure and enhancing caspase-dependent pathways of apoptosis.

STOBADINE PROTECTS RAT KIDNEY AGAINST ISCHAEMIA/REPERFUSION INJURY

1 Ischaemia–reperfusion (I/R) injury, one of the main causes of acute renal failure, still needs satisfactory treatment for routine clinical application. Stobadine, a novel synthetic pyridoindole anti‐oxidant, has the ability to reduce tissue injury induced by mechanisms involving reactive oxygen species during I/R. The aim of the present study was to determine the effects of stobadine on renal I/R injury. 2 Forty male Wistar rats were randomly divided into four groups as follows: sham, I/R, stobadine treated and I/R + stobadine treated. Stobadine (2 mg/kg, i.v.) was given intravenously to two groups of rats. The stobadine‐treated group was treated with stobadine following sham operation before the abdominal wall was closed, whereas the I/R + stobadine group received stobadine at the beginning of reperfusion. Renal I/R was achieved by occluding the renal arteries bilaterally for 40 min, followed by 6 h reperfusion. Immediately thereafter, blood was drawn and tissue samples were harvested to assess: (i) serum levels of blood urea nitrogen and creatinine; (ii) serum and/or tissue levels of malondialdehyde (MDA), glutathione (GSH), glucose 6‐phosphate dehydrogenase (G‐6PD), 6‐phosphogluconate dehydrogenase (6‐PGD), glutathione reductase (GR) and glutathione peroxidase (GPx); (iii) renal morphology; and (iv) immunohistochemical staining for P‐selectin. 3 Stobadine was able to significantly attenuate the renal dysfunction as a result of renal I/R injury. Iscahemia–reperfusion resulted in a significant increase in serum and kidney MDA levels and a decrease in serum and kidney GSH. Stobadine treatment at the beginning of reperfusion attenuated both the increased MDA levels and decreased GSH secondary to I/R injury. In addition, the decreased G‐6PD activity observed after I/R was significantly attenuated by stobadine treatment. Stobadine did not alter 6‐PGD activity after I/R. Neither GR nor GPx activity was significantly changed in the I/R alone or the I/R + stobadine groups compared with the sham group. In addition, stobadine decreased the morphological deterioration and high P‐selectin immunoreactivity secondary to renal I/R injury. 4 A pyridoindole anti‐oxidant, stobadine exerts a renal protective effect in renal I/R injury, which is probably due to its radical‐scavenging and anti‐oxidant activities.

Mutagenic and morphologic impacts of 1.8GHz radiofrequency radiation on human peripheral blood lymphocytes (hPBLs) and possible protective role of pre-treatment with Ginkgo biloba (EGb 761).

The mutagenic and morphologic effects of 1.8GHz Global System for Mobile Communications (GSM) modulated RF (radiofrequency) radiation alone and in combination with Ginkgo biloba (EGb 761) pre-treatment in human peripheral blood lymphocytes (hPBLs) were investigated in this study using Sister Chromatid Exchange (SCE) and electron microscopy. Cell viability was assessed with 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reduction assay. The lymphocyte cultures were exposed to GSM modulated RF radiation at 1.8GHz for 6, 8, 24 and 48h with and without EGb 761. We observed morphological changes in pulse-modulated RF radiated lymphocytes. Longer exposure periods led to destruction of organelle and nucleus structures. Chromatin change and the loss of mitochondrial crista occurred in cells exposed to RF for 8h and 24h and were more pronounced in cells exposed for 48h. Cytoplasmic lysis and destruction of membrane integrity of cells and nuclei were also seen in 48h RF exposed cells. There was a significant increase (p<0.05) in SCE frequency in RF exposed lymphocytes compared to sham controls. EGb 761 pre-treatment significantly decreased SCE from RF radiation. RF radiation also inhibited cell viability in a time dependent manner. The inhibitory effects of RF radiation on the growth of lymphoctes were marked in longer exposure periods. EGb 761 pre-treatment significantly increased cell viability in RF+EGb 761 treated groups at 8 and 24h when compared to RF exposed groups alone. The results of our study showed that RF radiation affects cell morphology, increases SCE and inhibits cell proliferation. However, EGb 761 has a protective role against RF induced mutagenity. We concluded that RF radiation induces chromosomal damage in hPBLs but this damage may be reduced by EGb 761 pre-treatment.

Changes in Isoprenaline-Induced Endothelium-Dependent and -Independent Relaxations of Aorta in Long-Term STZ-Diabetic Rats: Reversal Effect of Dietary Vitamin E

1. The present study concerns in vitro isoprenaline (ISO)-induced relaxation of aortic rings of long-term streptozotocin (STZ)-diabetic and nondiabetic rats, both with and without dietary vitamin E supplementation. 2. Incubation with propranolol, NG-nitro-L-arginine methyl ester and methylene blue, as well as absence of endothelium, all negatively affect the ISO-induced relaxations. 3. Thiobarbituric acid reactivity levels used as an index of lipid peroxidation are elevated in the aorta by diabetes. Four months of STZ-diabetes results in a significant increase in the ISO-induced relaxations together with endothelial dysfunction in the rat aorta. Diabetes also causes the loss of vascular integrity. 4. Dietary vitamin E supplementation during the last 2 months of diabetes allows normalization of the levels of lipid peroxides. This vitamin also completely reverses the increased sensitivity (pD2 value) of the aorta to ISO, whereas the maximum ISO-induced relaxations are partially restored after the treatment in diabetic rats. 5. The results suggest that ISO-induced relaxation in the aorta partially depends on the intact endothelium and that the endothelium-dependent relaxant effect of ISO is mediated by endothelium-derived relaxing factor. Results also indicate that abnormal vascular reactivity and structure of the diabetic rat aorta may be related to the increased lipid peroxidation. In conclusion, vitamin E can protect the arterial wall from oxidative stress-induced injury associated with chronic STZ-diabetes and allows normalization of the response to ISO and the structure of the aorta in diabetic rats.

The effect of taurine on renal ischemia/reperfusion injury

Summary.Ischemia-reperfusion (I/R) injury is one of the most common causes of renal dysfunction. Taurine is an endogenous antioxidant and a membrane-stabilizing, intracellular, free beta-amino acid. It has been demonstrated to have protective effects against I/R injuries to tissues other than kidney. The aim of this study was to determine whether taurine has a beneficial role in renal I/R injury. Forty Wistar-Albino rats were allocated into four groups as follows: sham, taurine, I/R, and I/R + taurine. Taurine 7.5 mg/kg was given intra-peritoneally to rats in the groups taurine and I/R + taurine. Renal I/R was achieved by occluding the renal arteries bilaterally for 40 min, followed by 6 h of reperfusion. Immediately thereafter, blood was drawn and tissue samples were harvested to measure 1) serum levels of BUN and creatinine; 2) serum and/or tissue levels of malondialdehyde (MDA), glutathione (GSH), glucose 6-phosphate dehydrogenase (G-6PD), 6-phosphogluconate dehydrogenase (6-PGD) and glutathione reductase (GSH-red); 3) renal morphology; and 4) immunohistochemical staining for P-selectin. Taurine administration reduced I/R-induced increases in serum BUN and creatinine, and serum and tissue MDA levels (p < 0.05). Additionally, taurine lessened the reductions in serum and tissue glutathione levels secondary to I/R (p < 0.05). Taurine also attenuated histopathologic evidence of renal injury, and reduced I/R-induced P-selectin immunoreactivity (p < 0.05). Overall, then, taurine administration appears to reduce the injurious effects of I/R on kidney.

Effects of single high-dose vitamin D3 on fracture healing

The benefits of vitamin D3 on fracture healing have been commonly demonstrated in vitamin-D3-depleted animal models. The aim of this study was to examine the effects of a single high dose of vitamin D3 on fracture healing in a healthy animal model, which has not been previously reported. Twenty healthy young adult guinea pigs were randomly divided into two groups as ‘control’ and ‘vitamin D’, and their right tibias were fractured with digital manipulation. Guinea pigs in vitamin D group were injected intramuscularly with 50000 IU/kg of vitamin D3. The animals were killed at 7, 14, 21 and 28 days following fracture. Ultrastructural analysis of the harvested tibias revealed that a single high dose of vitamin D3 stimulated fracture healing. The observed effects at the fracture zone in a healthy animal model included advancement of blood supply, acceleration of synthesis and organization of collagen fibres, acceleration of the proliferation and differentiation of osteoprogenitor cells, and activation of the mineralization of the matrix.

Improving fat graft survival through preconditioning of the recipient site with microneedling

Although fat grafts are considered the ideal soft-tissue fillers, the main concern dealing with this technique is not being able to predict long-term graft survival due to high absorption rates. The purpose of this study was to investigate the angiogenic effects of preconditioning the recipient area with micro-needling and to determine its overall impact on fat graft survival. The study consisted of a sham, control and study group. The source of fat was the Wistar albino rat inguinal fat pad while the recipient area was a dorsal subcutaneous pouch. The dorsal area was preconditioned with standard technique micro-needling 1-week prior to fat graft transfer in the study group while the control group did not undergo micro-needling. At the end of 15 weeks, morphological, biochemical, histological and immunohistochemical evaluation was carried out. Fat grafts in the study group had better integrity and a higher level of vascularity compared to the control group. Volume analysis demonstrated higher graft survival in the study group in comparison to the control group. Histomorphometric and immunohistochemical evaluation showed better graft integrity and uniform adipocytes, less fibrosis, less vacuolisation and inflammation and better vascularisation in the study group. Although higher triglyceride concentrations were measured for the study group, the difference between the two groups was statistically insignificant. In conclusion, fat grafting performed in an area preconditioned with micro-needling results in higher graft volume, better integrity and vascularisation and an overall higher graft survival rate.

Comparison of the effects of troxerutin and heparinoid on flap necrosis

We aimed to assess the effects of local troxerutin and heparinoid (HEP) treatments in a model of flap necrosis. Three groups of Wistar albino rats, each comprising 10 animals were used. A cranially based 6x3-cm full-thickness random-pattern skin flap was raised and sutured to the same area in each model. The control group was treated daily with normal saline, the second with topical HEP and the third with topical troxerutin. The amount of flap necrosis was measured in all groups by the end of the seventh day. Flap tissues were excised for histological analysis and evaluation of the expression of vascular endothelial growth factor (VEGF) levels. Assessment of the blood levels of nitric oxide was also performed in each animal by cardiac puncture. The mean area of flap necrosis was 110.6mm(2) in the control, 39.44 mm(2) in the troxerutin and 47.11 mm(2) in the heparinoid-treated rats. The treatment arms exhibited significant reduction in areas of flap necrosis, compared with the control group (p<0.001), but it was similar among treatment groups (p=0.60). The rates of fibroblast proliferation were decreased in control group as compared to HEP and troxerutin arms (p<0.001). The mean level of collagen density, collagen organisation, granulation tissue and demarcation were similar in all rats. Measurement of VEGF expression did not show any significant difference between the groups (p=0.30). Nitric oxide levels were significantly higher in control rats, as compared to treatment groups (p<0.0001), but were similar in treatment arms (p=0.45). Our results suggest that troxerutin and HEP effectively reduce the flap necrosis and improve flap survival. The observed effects might be due to their anti-oedematogenic, radical-scavenging, antioxidant effects and supportive activities on capillary permeability and transudation.

Effects of Melatonin on Ischemic Spinal Cord Injury Caused by Aortic Cross Clamping in Rabbits

Spinal cord injury remains a devastating complication of thoracic and thoracoabdominal aortic operations. We aimed to investigate neuro-protective role of melatonin administered to rabbits before ischemia against ischemia-reperfusion (IR) injury. Occlusion of the abdominal aorta was applied to adult rabbits, followed by removal of aortic clamp and reperfusion. The abdominal aortas of New Zealand White albino rabbits (n = 18) were occluded for 30 minutes. Experimental groups were as follows: control group (sham operation group, n =10), Ischemia/reperfusion group (I/R) (n = 10) undergoing occlusion but receiving no pharmacologic intervention, Melatonin-treated group (n = 8) receiving 10mg/kg melatonin intravenously 10 minutes before ischemia. Neurologic status was assessed at 6, 24, and 48 hours after the operation. Spinal cords were harvested for histopathologic and biochemical analyses. Melatonin-treated animals had better neurologic function than those of the I/R group. Decreased tissue and serum malondialdehyde (MDA) levels and increased tissue and serum glutathione (GSH) levels were observed in melatonin-treated group (p<0.05). In the same group tissue and serum nitrate levels were decreased (p<0.05). Histopathologic analyses demonstrated typical morphologic changes characteristic of necrosis in I/R group. Melatonin attenuated ischemia-induced necrosis. Melatonin administration may significantly reduce the incidence of spinal cord injury following temporary aortic occlusion.