¹H-MRS before and after resuscitation following selective cerebral ultra-profound hypothermic blood flow occlusion in monkeys.

We investigated the effect of selective cerebral ultra-profound hypothermic blood flow occlusion on brain tissue and cell metabolism to ascertain the efficacy and safety of selective deep hypothermic technologies using proton magnetic resonance spectroscopy ((1)H-MRS). The bilateral carotid artery was blocked at room temperature for 10 min. Other neck vessels were then blocked through cold perfusion of the internal carotid artery and reflux of the ipsilateral jugular vein. Thus, selective cerebral extracorporeal circulation was established. Brain temperature was reduced to 15.1° ± 0.9°C. After 60 min, cerebral blood flow recovered naturally. Routine magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), and (1)H-MRS examination of the bilateral frontal cortex and basal ganglia were performed prior to surgery and 4, 24, 72 h, 21 days after recovery. The formants and areas under the curve (AUC) of N-acetyl aspartate (NAA), choline (Cho), creatine/phosphocreatine (Cr/Cr2) were analyzed using 1H-MRS. The pre- and postoperative AUC of NAA and Cho at different time points were compared. Conventional MRI and DWI showed no abnormal signal changes in the brain parenchyma or right basal ganglia before and after surgery (P > 0.05). There was no significant difference in the ratio between NAA/(Cr+Cr2) and Cho/(Cr+Cr2) before and after surgery in the bilateral basal ganglia and frontoparietal regions of the cortex (P > 0.05). Quantitative (1)H-MRS showed that selective deep cerebral hypothermia significantly improved the brain's tolerance to ischemia and hypoxia. Our results could provide a better understanding of the efficacy and safety of selective deep hypothermia and blood flow occlusion.

Changes in hippocampal ultrastructure and vimentin expression in rhesus monkeys following selective deep hypothermia and blood occlusion.

Previous studies have shown that selective cerebral profound hypothermia combined with antegrade cerebral perfusion can improve resistance to cerebral hypoxia-ischemia in monkeys. The aim of this study was to observe the effect of selective cerebral profound hypothermia on the ultrastructure and vimentin expression in monkey hippocampi after severe cerebral ischemia. Eight healthy adult rhesus monkeys were randomly divided into two groups: profound hypothermia (N = 5) and normothermia (N = 3). Monkeys in the profound hypothermia group underwent bilateral carotid artery and jugular vein occlusion for 10 minutes at room temperature. Ringer's solution at 4°C was then perfused through the right internal carotid artery and out of the right jugular vein, maintaining the brain temperature below 18°C. Sixty minutes later, cerebral blood flow was restored. The normothermia group underwent all procedures with the exception that the Ringer's solution was 37°C during perfusion. All animals in the profound hypothermia group were successfully resuscitated. No significant abnormalities of hippocampal morphology or ultrastructure were observed. In contrast, no monkeys were alive after perfusion in the normothermia group and they had abnormal hippocampal morphology and ultrastructure to different extents. Vimentin expression in the hippocampus was significantly lower in the profound hypothermia group (47.88% ± 1.66) than the normothermia group (79.51% ± 1.00; P < 0.01). We conclude that selective cerebral profound hypothermia following 10-min occlusion of the bilateral common carotid arteries was able to downregulate vimentin expression in the hippocampus and protect it from severe cerebral ischemia.