The role of hepatobiliary scintigraphy in the evaluation of the protective effects of dimethylsulphoxide in ischaemic/reperfusion injury of liver

Nuclear imaging techniques for the assessment of hepatic function in liver surgery and transplantation

This review describes the application of 2 nuclear imaging techniques for assessment of hepatic function in the setting of liver surgery and transplantation. The biochemical and technical background, as well as the clinical applications, of (99m)Tc-labeled diethylenetriaminepentaacetic acid galactosyl human serum albumin (GSA) scintigraphy and hepatobiliary scintigraphy (HBS) with (99m)Tc-labeled iminodiacetic acid derivates is discussed. (99m)Tc-mebrofenin is considered the most suitable iminodiacetic acid agent for (99m)Tc-HBS. (99m)Tc-GSA scintigraphy and (99m)Tc-mebrofenin HBS are based on 2 different principles. (99m)Tc-GSA scintigraphy is a receptor-mediated technique whereas HBS represents hepatic uptake and excretion function. Both techniques are noninvasive and provide visual and quantitative information on both total and regional liver function. They can be used for preoperative assessment of future remnant liver function, follow-up after preoperative portal vein embolization, and evaluation of postoperative liver regeneration. In liver transplantation, these methods are used to assess graft function and biliary complications.

How DMSO, a widely used solvent, affects spinal cord injury

The aim of this experimental study was to investigate whether dimethylsulfoxide (DMSO) has protective effects on spinal cord ischemia-reperfusion (I/R) injury. New Zealand rabbits were enrolled in the study. In addition to the control group, the study group received 0.1 mL/kg DMSO prior to ischemia. Blood samples were taken to obtain nitrite-nitrate levels during the surgical procedure. After neurological evaluation at 24 hr of reperfusion, lumbar spinal cords were removed for electron microscopic evaluation and malondialdehyde and myeloperoxidase measurements. The mean Tarlov score of the DMSO group was higher than that of the control group. Electron microscopic examination was carried out with tissue samples at 24 hr of reperfusion. The DMSO group had better preservation with the electron microscopic scoring compared to the control group. Malondialdehyde and myeloperoxidase levels were decreased in the DMSO group compared to the control group. Nitrite-nitrate levels were also lower in the DMSO group compared to control at 5 and 30 min of reperfusion. This study demonstrates a considerable neuroprotective effect of DMSO on neurological, biochemical, and histopathological analyses during periods of spinal cord I/R injury in rabbits. Although there was a difference between the DMSO and control groups in all measured parameters in our study, this was not statistically significant. DMSO deserves further investigation related with spinal cord ischemia and reperfusion. We should also consider the effect of DMSO when we use it as a solvent or vehicle during experimental I/R models.

Antiapoptotic effect and inhibition of ischemia/reperfusion-induced myocardial injury in metallothionein-overexpressing transgenic mice

Previous studies using a cardiac-specific metallothionein (MT)-overexpressing transgenic mouse model have demonstrated that MT inhibits ischemia/reperfusion-induced myocardial injury. The present study was undertaken to test the hypothesis that the MT inhibition is associated with suppression of apoptosis mediated by mitochondrial cytochrome c release and caspase-3 activation. An open-chest coronary artery occlusion and reperfusion procedure to produce ischemia/reperfusion-induced left ventricle infarction was used in MT-overexpressing transgenic mice and non-transgenic controls. After 30 minutes of ischemia, the left ventricle was reperfused to allow blood flow through the previously occluded coronary artery bed. Myocardial infarction produced after reperfusion for 4 hours was significantly reduced in the MT transgenic mice. This inhibition correlated with the antiapoptotic effect of MT, as determined by a terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick-end labeling assay, mitochondrial cytochrome c release and caspase-3 activation. Ischemia/reperfusion-induced lipid peroxidation was also significantly inhibited in the MT-transgenic heart. Dimethylsulfoxide, a chemical scavenger for reactive oxygen species, was used to confirm the antioxidant effect of MT and found to suppress myocardial infarction and lipid peroxidation just as MT did. This study thus demonstrates that MT suppresses ischemia/reperfusion-induced myocardial apoptosis through, at least in part, the inhibition of cytochrome c-mediated caspase-3 activation pathway. The antiapoptotic effect of MT likely results from the suppression of oxidative stress and correlates with the inhibition of myocardial infarction.

Hepatobiliary scintigraphy for evaluating the hepatotoxic effect of halothane and the protective effect of catechin in comparison with histo-chemical analysis of liver tissue

Halothane and its metabolites cause liver damage by decreasing liver blood flow and generating free-radical species. Catechin suppresses lipid peroxidation and increases enzyme activity, therefore it seems to be capable of protecting liver parenchyma against the direct toxic effect of halothane. The aim of this study was to investigate the role of hepatobiliary scintigraphy in detecting liver damage after halothane anaesthesia and the protective effect of catechin in comparison with histo-chemical analysis. Thirty rabbits, divided into three groups (A, controls; B, halothane; and C, catechin+halothane), were investigated. In group A no anaesthesia was administered. Group B only received halothane, while group C was pretreated with catechin and halothane anaesthesia was administered for 2 h. Dynamic scintigrams were taken for 60 min after injecting 99mTc-mebrofenin, and the time of peak uptake (TPU) and the time for half of the activity to clear from the liver (T(1/2)) were calculated. Rabbits were killed, and malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) levels were measured in hepatic tissue. The TPU and T(1/2) values of group A is significantly lower than in groups B and C (P<0.0002 and P<0.0002, respectively, for TPU; and P<0.0002 and P<0.0003, respectively, for T(1/2)). The TPU and T(1/2) values of group B were significantly higher than in group C (P<0.0003 and P<0.0003, respectively). The hepatic MDA level of group A was significantly lower than in groups B and C (P<0.0002 and P<0.0002, respectively). SOD, GSH-Px and CAT levels of group A were significantly higher than in groups B and C (P<0.0002, P<0.0001 and P<0.003, respectively, for group A vs group B; and P<0.0005, P<0.0002 and P<0.03, respectively, for group A vs group C). The MDA level of group B was significantly higher than that in group C (P<0.0002). SOD, GSH-Px and CAT levels of group B were significantly lower than in group C (P<0.0002, P<0.0002 and P<0.003, respectively). According to these results, we suggest that catechin protects liver parenchyma against the toxic effect of halothane and its metabolites, and that, compared to invasive histo-chemical analysis, hepatobiliary scintigraphy is a useful and alternative non-invasive method for detecting the protective effect of catechin on liver parenchyma after halothane anaesthesia.