Effects of Susceptibility Artifacts on Perfusion MRI in Patients with Primary Brain Tumor: A Comparison of Arterial Spin-Labeling versus DSC.

BACKGROUND AND PURPOSE: Our aim was to investigate the effects of intratumoral hemorrhage, calcification, and postoperative changes on the sensitivity of arterial spin-labeling and DSC perfusion MR imaging in patients with primary brain tumors. MATERIALS AND METHODS: Eighty-six brain tumor lesions were examined with single-phase and multiphase arterial spin-labeling and DSC perfusion MR imaging. The lesions that had no intratumoral bleeding/calcifications and history of surgery were assigned to group 1 (n = 38), and the lesions that had these were assigned to group 2 (n = 48). The relative regional cerebral blood flow was calculated in both perfusion methods, and relative regional cerebral blood volume was calculated in DSC. Imaging results were correlated with histopathology or follow-up. RESULTS: In the quantitative evaluation, the sensitivity and specificity of relative regional cerebral blood flow in multiphase arterial spin-labeling perfusion were 94.4% and 80% in group 1 and 78.3% and 88% in group 2, respectively. The sensitivity and specificity of relative regional cerebral blood flow in DSC perfusion were 88.9% and 75% in group 1 and 78.3% and 84% in group 2, respectively. The sensitivity and specificity of relative regional cerebral blood volume in DSC perfusion were 66.7% and 100% in group 1 and 69.6% and 96% in group 2, respectively. In the qualitative evaluation, the sensitivities for single-phase and multiphase arterial spin-labeling were 48.2% and 79.3%, respectively, with 100% specificity for both. CONCLUSIONS: The sensitivity and specificity of multiphase arterial spin-labeling were similar to those of DSC perfusion irrespective of bleeding and calcification in primary brain tumors. Thus, we suggest that noncontrast multiphase arterial spin-labeling can be used instead of DSC perfusion MR imaging in the diagnosis and follow-up of intracranial tumors.

Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic.

Ocean plastic can persist in sea surface waters, eventually accumulating in remote areas of the world's oceans. Here we characterise and quantify a major ocean plastic accumulation zone formed in subtropical waters between California and Hawaii: The Great Pacific Garbage Patch (GPGP). Our model, calibrated with data from multi-vessel and aircraft surveys, predicted at least 79 (45-129) thousand tonnes of ocean plastic are floating inside an area of 1.6 million km2; a figure four to sixteen times higher than previously reported. We explain this difference through the use of more robust methods to quantify larger debris. Over three-quarters of the GPGP mass was carried by debris larger than 5 cm and at least 46% was comprised of fishing nets. Microplastics accounted for 8% of the total mass but 94% of the estimated 1.8 (1.1-3.6) trillion pieces floating in the area. Plastic collected during our study has specific characteristics such as small surface-to-volume ratio, indicating that only certain types of debris have the capacity to persist and accumulate at the surface of the GPGP. Finally, our results suggest that ocean plastic pollution within the GPGP is increasing exponentially and at a faster rate than in surrounding waters.

Protective effects of N-acetylcysteine on peroxidative changes of the fetal rat lungs whose mothers were exposed to cigarette smoke.

BACKGROUND: This experimental study investigated the protective effects of N-acetylcysteine (NAC) on peroxidative changes in fetal lungs in the offspring of rats exposed to cigarette smoke. METHODS: Thirty fetal rats used for analysis, were divided into three groups as follows: control group (n = 10), whose mothers were exposed to fresh air; group I (n =10), whose mothers were exposed to cigarette smoke; and group II (n =10), whose mothers were exposed to cigarette smoke and given 10 mg/kg per day NAC. In groups I and II, smoke exposure was started 4 weeks before the pregnancy, and continued to the 14th day of pregnancy, and in Group II, NAC was administered intraperitoneally for 14 days. The mothers and their fetuses were decapitated on the 14th day of pregnancy. Malondialdehyde (MDA) and glutathione (GSH) levels were determined in the lung tissues of fetuses to determine the oxidant-antioxidant balance. RESULTS: While tissue MDA levels in Group I were found significantly higher than the control group (129.7+/-65.4 versus 63.4 +/-15.4 nmol/100 mg protein, P <0.05), GSH levels were significantly lower (17.1+/-7.3 versus 45.4 + 8.1 nmol/mg protein, P <0.01). Furthermore, in Group II, MDA levels were significantly lower (56.9+/-20.6 versus 129.7+/-65.4 nmol/100 mg protein, P <0.05), and GSH levels were significantly higher (34.57+/-10.7 versus 17.1+/-7.3 nmol/mg protein, P <0.0001) when compared with Group I. No statistically significant difference was found in tissue MDA and GSH levels between Group II and the control group (P >0.05). CONCLUSIONS: These results suggest that smoke exposure during pregnancy causes oxidative damage in fetal lungs. This smoke-induced damage might be prevented by NAC.

Protective antioxidant effects of carvedilol in a rat model of ischaemia-reperfusion injury.

This study investigated the protective effects of carvedilol, a potent antioxidant, in a rat model of tourniquet-induced ischaemia-reperfusion injury of the hind limb. Thirty rats were divided equally into three groups: the control group (group 1) was only anaesthetized, without creating an ischaemia-reperfusion injury; group 2 was submitted to ischaemia (4 h), followed by a 2-h reperfusion period; and group 3 was pre-treated with carvedilol (2 mg/kg per day) for 10 days prior to ischaemia-reperfusion. Ischaemia-reperfusion produced a significant decrease in superoxide dismutase and glutathione peroxidase activities in the liver, lungs, muscle and serum compared with control treatment, and pre-treatment with carvedilol prevented these changes. Ischaemia-reperfusion caused a significant increase in malondialdehyde and nitric oxide (NO) levels in liver, lungs, muscle (except NO) and serum compared with control treatment, and carvedilol prevented these changes. In conclusion, it might be inferred that carvedilol could be used safely to prevent oxidative injury during reperfusion following ischaemia in humans.

Effect of the prostacyclin derivate iloprost in experimental caustic esophageal burn.

Previous experimental studies have suggested that administration of antithrombotic, antioxidant, and cytoprotective agents have protective effects in caustic injury of the esophagus. Therefore, an experimental study was carried out to investigate the effects of iloprost, a stable analogue of prostacyclin, on the esophagus after caustic burns. Sixty Wistar albino rats were divided into three groups of 20 animals each. In group A, animals were uninjured and untreated. In group B, animals were injured but untreated. In group C, rats were injured and administered intravenous iloprost for 3 days. Caustic esophageal burn was produced by 1 ml of 15% NaOH. Efficacy of the treatment was assessed by measuring the tissue malondialdehyde (MDA), superoxide dismutase, and glutathione levels with biochemical methods on the 3rd postoperative day. Histopathological evaluation was done on the 28th postoperative day. The level of MDA was significantly increased in group B compared with the other groups. In group B, the histopathological damage score was significantly higher than in groups A and C. There was also a significant difference between groups A and C regarding the histopathologic damage. These results indicate that iloprost has a preventive effect in experimental caustic esophageal burn in rats.