Immunohistochemical Study of the Expression of pERK1/2 Protein in the Forebrains of Adult Rodents Following Hypoxia-ischemia injury

PURPOSE: The purpose of this study was to evaluate spatiotemporal evaluation of pERK1/2 protein expression in the forebrain following hypoxic-ischemic (HI) injury in adult Sprague-Dawley rats. METHODS: HI injury was induced by occlusion of the bilateral common carotid artery (CCA) and respiration with 5% O2 hypoxic gas for 8 minutes, followed by unilateral release of CCA. RESULTS: Immunoreactivity for pERK1/2 protein in the bilateral cortex began to increase at 2 hours, reached peak levels at 6 hours, and then decreased by 24 hours after HI injury. In a cortical neuron, the expression of pERK1/2 protein was observed in all cellular components and processes including dendrites, cell body and nuclei at 6 hours, but persisted only in the cell body by 24 hours after HI injury. Temporal changes in the immunoreactivity for pERK1/2 protein in the hippocampus was very similar to that of the cortex following HI injury. In contrast, the temporal changes in the cellular distribution of pERK12 protein in hippocampal neurons was largely different from that of the cortex following HI injury. CONCLUSION: The results of the present study suggest that HI injury causes an early activation of ERK1/2 signaling with a differential cellular distribution of pERK1/2 protein among different forebrain structures. Further study needs to be done in order to elucidate a possible role of ERK1/2 signaling for neural damage in the adult rodent HI model.

Effects of alpha-Lipoic Acid on Apoptotic Cell Death in Rat Hippocampus Following Transient Forebrain Ischemia-reperfusion Injury

PURPOSE: The purpose of this study was to evaluate effect of alpha-lipoic acid on apoptotic cell death in rat hippocampal neuron following transient forebrain ischemia-reperfusion (I/R) injury. METHODS: The four-vessel occlusion method was used to induce transient I/R injury in the forebrain of Sprague-Dawley rats. In the treatment group, alpha-Lipoic acid (LA) was administered subcutaneously at 50 mg/kg/day for 7 days before induction of I/R injury. RESULTS: Pretreatment with LA significantly reduced the number of TUNEL-positive neurons in the pyramidal cells layer of the hipocampal CA1 region 5 days after the ischemia, suggesting a marked reduction of apoptotic cell death. Pretreatment with LA also resulted in marked suppression at the transcript level of mRNA for caspase-3 at 24 hours, and decreased concentration of the active form of caspase-3 protein in the hippocampus at 1, 3, and 5 days after I/R injury. Furthermore, as indicated by western blot analysis, the concentration of apoptosis-inducing factor (AIF) in the hippocampus was reduced at 1 and 3 days after a transient I/R injury by pretreatment with LA. CONCLUSION: The results of this study suggest that LA has the potential to prevent neuronal cell death in the hippocampus by inhibiting intracellular signaling pathways responsible for apoptosis following transient I/R injury.

Immunohistochemical Study for Expression of cFos, pERK1/2 and pAkt Proteins in a Macrosphere Animal Model for Permanent Focal Brain Ischemic Injury

PURPOSE: Recently, a new animal model for permanent focal brain ischemia using macrospheres was developed wherein the hypothalamic area was free from ischemic injury. The purpose of this study was to evaluate spatiotemporal changes in the expressions of cFos, pERK, and pAkt proteins in the macrosphere model. METHOD: Three or four macrospheres were injected into the internal carotid artery after ligation of the external carotid artery to induce permanent focal brain ischemic injury. RESULT: Twenty-four hours after macrosphere injection, 2,3,5-Triphenyltetrazlium (TTC) staining showed a marked ischemic injury in the blood supply territory of the middle cerebral artery, for example, the cerebral cortex and striatum. Furthermore, TUNEL staining revealed apoptotic cell death in the ischemic injury region of the cerebral cortex and striatum. Expression of the cFos protein was significant in the penumbral zone, but not in the ischemic core of the cortex and striatum, two and six hours after ischemic insult. A transient prominent expression of the pERK1/2 protein was noted in the penumbral zone of the cortex and striatum two hours after injection of macrospheres. In contrast, there was a strong immunoreactivity for the pAkt protein in the ischemic core, but not in the penumbral zone of the cortex and striatum, six hours after ischemic injury. CONCLUSION: The above results suggest that early expressions of cFos, pERK1/2, and pAkt proteins take part in different signaling cascades for cell survival or death in macrosphere animal model of permanent focal brain ischemic injury.

Efficacy of Aquacell(R) Dressing in Partial Thickness Burn Patients

In partial thickness burn injuries, silver sulfadiazine cream 1%(SSD, Silvadene(R)) is the most commonly used topical agent worldwide. But silver sulfadiazine cream 1% has no exudate absorption property. Usually after escar is removed from wound surface, Silvadene(R) is changed to saline wet gauze dressing to promote epithelization. Aquacel(R)(ConvaTec, UK) is a 100% sodium carboxymethylcellulose Hydrofiber material. It absorbs exudates directly into the hydrofibers by vertical wicking which allows rapid uptake of liquid into the fibers. The absorbed exudate fluid can be distributed to the entire dressing rather than just over the wound surface, which results in larger fluid absorption capacity. From April, 2003 to July, 2004 a study was done with 40 patients who had variable partial thickness burns. Aquacel(R) dressing was compared in 21 cases to silver sulfadiazine cream 1% and saline wet gauze dressings in 19 cases. In the Aquacel(R) cases, the average healing time on the face was 5.36+/-1.69 a day; on the hands was 8.46+/-2.15 a day; and, on the neck was 6.0+/-2.0 a day. With the Silvadene(R) and Saline wet gauze dressing, the average healing time on the face was 6.44+/-1.74 a day; on the hands was 13.79+/-5.35 a day; and, on the neck was 11.17+/-3.31 a day. As a result, the Aquacel(R) group showed a shorter healing time compared to the Silvadene(R) and saline wet gauze dressing group and patients were satisfied because of less pain and improved comfort. In conclusion, Aquacel(R) is a better choice for partial thickness burn injuries because of shorter healing time, less pain and more confortable dressing.

Expressions of the pERK1/2 and the cFos Proteins at an Early Stage of Transient Global Ischemia-reperfusion Injury in the Hippocampus of Rats

PURPOSE: This study was to evaluate temporal changes in the expressions of the phosphorylated extracellular-regulated kinase1/2 (pERK1/2), the phosphorylated MAPK/ERK kinase1/2 (pMEK1/2) and the cFos proteins in the hippocampus of rats following transient global ischemia. METHODS: Transient global ischemia was induced in the forebrains of Sprague-Dawley rats by using a 4-vessel occlusion for 20 min under anesthetic condition. Hematoxyline-eosin staining showed typical microscopic findings that represented neuronal cell death in hippocampal CA1 regions 5 days after transient global ischemia. Four-vessel occlusion-reperfusion produced ischemic injury in major forebrain structures, such as the striatum, the cortex and the hippocampus, in the finding of triphenyltetrazolium chloride (TTC) staining. RESULTS: A high density of pERK1/2 immunoreactivity existed in the pyramidal-cell layers of the CA2-3 regions and in the granular-cell layers of the dentate gyrus 5 min after ischemia. Following ischemia, expression of the pMEK1/2 protein showed temporal changes similar to that of the pERK1/2 protein. A significant expression of the cFos protein was noted in the pyramidal-cell layers of the CA2-3 regions and in the granular-cell layers of the dentate gyrus 2 hours after global ischemia. CONCLUSION: Intracellular signaling cascades of the ERK or the cFos protein take part in early cellular events in the hippocampus of rats in response to ischemic insult.