Effects of Ozone on Injury after Gamma Knife Radiosurgery.

BACKGROUND: At present, gamma knife radiosurgery plays an important role in neurosurgical procedures. Gamma knife radiosurgery has been used to treat many types of brain tumors and as a functional intervention. However, gamma knife treatment has a devastating effect on the normal brain parenchyma surrounding the target point. It causes increased vascular permeability, vasodilation, and swelling in endothelial cells. Ozone has antioxidant, antiapoptotic, and anti-inflammatory effects in the body. Thus, we evaluated the radioprotective effects of ozone in rats undergoing gamma knife radiation. METHODS: In the present study, 24 Sprague-Dawley male rats weighing 250-300 g in 3 groups of 8 rats each were used. The rats were selected randomly. The control group did not receive any gamma knife radiation. The other 2 groups received 50 Gy of radiation, with 1 group given ozone treatment and the other group not given ozone treatment after gamma knife radiosurgery. At 12 weeks after gamma knife radiation, the rats were sacrificed with high-dose anesthetic agents and the tissues prepared for evaluation. The slides were evaluated for necrosis, vacuolization, glial proliferation, and vascular proliferation using hematoxylin-eosin staining. Vascular endothelial growth factor (VEGF) and extracellular matrix metalloproteinase inducer (also known as CD147) were evaluated using immunohistochemical staining. RESULTS: VEGF expression in glial tissue was significantly less in the group receiving ozone (χ2 = 15.00; df = 4; P = 0.005) compared with the group that had not received ozone and was similar to the expression in the control group. CONCLUSIONS: The lower expression of VEGF in the group receiving ozone might cause less edema in the surrounding tissue owing to less degradation of vascular permeability in the rat brain tissue.

Functional Reorganization in the Primary Somatosensory Cortex of Rat Following Hind-Paw Amputation: A Study of Functional Imaging with 1.5 Tesla MRI.

AIM: To learn how rat primary somatosensory cortex (pSSC) responses to the loss of inputs from hind-paw, using fMRI of an inferior magnetic power (1.5 Tesla) with special designed high-powered rat coil. MATERIAL AND METHODS: Ten adult male Sprague-Dawley rats were enrolled in this study. The rats were anesthetized with ketamine injection. Xylazine was intraperitoneally injected for analgesia and muscle relaxation with careful maintenance of spontaneous respiration. Either right or left hind-paws were amputated under aseptic conditions according to predefined random allocation of the rats. A 12-channel rat surface coil developed for proper image resolution in 1.5 Tesla MR was used. Functional magnetic resonance imaging was obtained before hind-paw amputation; 2, 15 and 30 days after the amputation. RESULTS: Activation signals were detected in 5 rats' contralateral pSSC before the hind-paw amputation with regression and cessation of the signal after the amputation. Signal re-appeared in the contralateral pSSC of only one rat (rat 9) 30 days after the amputation. CONCLUSION: This study showed that functional plasticity might occur in the pSSC following hind-paw amputation of rats. Further studies are necessary to understand the true nature of the plasticity observed in pSSC, with new and novel measurement techniques on cellular basis rather than gross anatomical one.

Immunohistochemical Grading of Epidural Fibrosis with CD105 Antibody.

OBJECTIVE: Grading of epidural fibrosis (EF) is usually performed by histopathologic staining in experimental studies. Immunohistochemical methods for grading are not available in routine practice yet. In our study, the effect of tranexamic acid (TXA), a commonly used hemostatic agent in surgical interventions, was evaluated for use against the development of EF with classical histopathologic methods and immunohistochemistry using the CD105 antibody, a marker of angiogenesis. METHODS: Sixteen rats were used. The rats were assigned to 2 groups, control and TXA. Laminectomy was performed on the control group. In the treatment group, laminectomy + topical TXA was applied. After sacrificing the rats in the sixth week, histopathologic and immunohistochemical examinations and grading of the EF tissue were performed. RESULTS: Conventional histopathologic parameters of fibroblast count, intensity of fibrosis density, and inflammatory cell density, as well as immunohistochemical evaluation with CD105, showed that the grading of EF was comparable between groups I and II (P < 0.001). DISCUSSION: The results of our study have demonstrated that CD105 is compatible with the conventional histopathologic grading methods and can be used as a marker to determine the grades of angiogenesis and fibrosis in experimental studies. The results of our study have also shown that TXA, administered locally for hemostasis, reduces the grade of EF in rats following laminectomy. TXA has been observed to cause no toxic effects on neural tissue as it is already commonly used in clinical practice.

Impact of sorafenib on epidural fibrosis: An immunohistochemical study.

AIM: To determine if sorafenib, an antineoplastic agent, could prevent the development of spinal epidural fibrosis (EF). METHODS: The study used CD105 and osteopontin antibodies in an immunohistochemical approach to quantify EF that occurred as a consequence of laminectomy in rats. Wistar albino rats (n = 16) were divided into two groups: control (L1-2 level laminectomy only) and sorafenib treatment (L1-2 level laminectomy + topical sorafenib). The animals were euthanatized after 6 wk, and the EF tissues were examined for histopathological changes after immunohistochemical staining. The EF grades were assigned to the tissues, and the treatment and control groups were compared. RESULTS: The EF thickness, inflammatory cell density, and arachnoid adherences determined by light microscopy were significantly higher in the control group compared to the sorafenib-treated group. Based on fibrosis scores, the extent of EF in the treatment group was significantly lower than in the controls. Immunohistochemical staining for CD105 to identify microvessels revealed that the EF grades based on vessel count were significantly lower in the treatment group. Staining for osteopontin did not show any significant differences between the groups in terms of the extent of EF. The staging of EF based on vascular counts observed after immunohistochemical staining for CD105, but not for osteopontin, was compatible with conventional staging methods. Neither toxic effects on tissues nor systemic side effects were observed with the use of sorafenib. CONCLUSION: Local administration of sorafenib significantly reduced post-laminectomy EF. Decreased neovascularization in spinal tissue may be due to the sorafenib-induced inhibition of vascular endothelial growth factor.

Morphometric Analysis of the Effects of Manuka Honey on Vasospastic Femoral Arteries in Rats: An Experimental Study.

OBJECTIVES: The aim of this study was to determine if Manuka honey, a potent anti-inflammatory and antioxidant agent, had any effect on the development of vasospasm in an experimental subarachnoidal hemorrhage model constructed in rat femoral arteries. METHODS: Twenty-four Wistar Albino strain rats were divided into 3 groups: Group 1 was the control group (n=8), Group 2 was the vasospasm group (n=8), and group 3 was the treatment group (n=8). The wall thickness (W) of the femoral arteries and the luminal diameter (L) were measured using morphometric methods. The data were analyzed with statistical software. The Mann-Whitney U-test was used to compare independent groups and Bonferroni post hoc analysis was used for multiple comparison tests. Significance for all of the results was established at p<0.05. RESULTS: A statistically significant intergroup difference was detected in the mean L and W (p<0.001, p=0.001, respectively). The mean L value in Group 2 was statistically significantly less than that of Groups 1 and 3, while the mean W value was significantly greater (p<0.001 for all). However, no statistically significant difference was detected between Groups 1 and 3 with respect to the mean L and W values (p=0.064, p=0.954, respectively). CONCLUSION: Manuka honey exerts an antioxidant and anti-inflammatory effect via inhibition of inflammatory cytokines, including plasma tumor necrosis factor alpha, interleukin (IL)-1 beta, IL-6, and the lipid peroxidation level. This study statistically demonstrated that the anti-inflammatory and antioxidant properties of Manuka honey successfully inhibited the development of vasospasm in an experimentally induced vasospasm model in the femoral arteries of rats.

In vivo effect of pregnancy on angiogenesis potential of arteriovenous malformation tissue samples: an experimental study.

BACKGROUND: Increased angiogenic potential of cerebrovascular malformations during pregnancy may help to explain the complications of arteriovenous malformations (AVMs) in this group of patients. This experimental study investigated the effect of pregnancy on angiogenic activity of implanted AVM tissue samples. METHODS: A subject group of 10 pregnant rats and 10 non-pregnant rats as controls were used. Surgical AVM resection samples were implanted into the micropocket created in both eyes of each animal. Vascular development was assessed by vessel count throughout the study period. In addition, immunohistochemical studies were done for vascular endothelial growth factor (VEGF), platelet derived growth factor (PDGF), and their receptors (VEGFR, PDGFR). RESULTS: Statistically significant increase in the number of vessels was found in both groups (P<0.0001); however, the increase in the pregnant group was greater (P=0.0032). The difference between the two groups was evident at the 25th day of the experiment. Despite both groups showed increased level, there was no difference with the level of VEGF, VEGF receptor, PDGF, or PDGF receptor (P>0.05 for all comparisons). CONCLUSIONS: Findings of this study suggest that angiogenic activity of AVM tissues may increase during late pregnancy, hence physicians should inform pregnant patients with AVM of the potential risk.

Effect of hyperbaric oxygen therapy on cerebral vasospasm: a vascular morphometric study in an experimental subarachnoid hemorrhage model.

This study was undertaken to investigate the preventive or therapeutic effect of hyperbaric oxygen therapy (HBOT) on cerebral vasospasm following experimental subarachnoid hemorrhage (SAH). Twenty rabbits were assigned randomly to one of four groups. Animals in Group I were not subjected to SAH or sham operation (control group, n = 5). Animals in Group II were subjected to sham operation and received no treatment after the procedure (sham group, n = 5). Animals in Group III were subjected to SAH and received no treatment after SAH induction (SAH group, n = 5). Animals in Group IV were subjected to SAH and received five sessions of HBOT at 2.4 atmospheres absolute (ATA) for 2 h (treatment group, n = 5). Animals were euthanized by perfusion and fixation 72 h after procedures. Basilar artery vasospasm indices, arterial wall thicknesses, and cross-sectional luminal areas were evaluated. Statistical comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests. Mean basilar artery vasospasm index in the treatment group was significantly smaller than in the SAH group. Mean basilar artery wall thickness in the treatment group was significantly smaller than in the SAH group. Mean basilar artery cross-sectional luminal area in the treatment group showed an increase relative to the SAH group, but this difference remained statistically insignificant. Our results demonstrated that repeated application of HBOT at 2.4 ATA for 2 h attenuated vasospastic changes such as increased vasospasm index and arterial wall thickness. HBOT is thus a promising candidate for SAH-induced vasospasm. Further studies are needed to evaluate maximal effect and optimal application regimen.