脂肪干细胞治疗下肢缺血的研究进展

下肢缺血性疾病是临床常见的严重危害中老年人健康的疾病之一。目前，临床针对下肢缺血性疾病的治疗方法多样，但远 期疗效欠佳，对于肢体严重缺血的患者往往需要进行截肢处理。脂肪干细胞（adipose-derived stemcells, ADSCs）作为再生医学用 于治疗下肢缺血的种子细胞具有广阔的应用前景。本文将对ADSCs 治疗下肢缺血的研究进展进行综述。     

Effect of ischemia-reperfusion injury on the morphology of peroxisomes

We have previously demonstrated that ischemic injury changed the density of peroxisomes into two distinct peaks, one with a normal density (1.21 g/cm³; Peak I) and a second peak with a lighter density (1. 14 g/cm³; Peak II).We studied the peroxisomes from both peaks under the Electron microscope. Examination of peak I following ischemia showed loss of matrix proteins and damaged limiting membranes with leakage of DAB positive material in direct proportion to the duration of ischemia. Upon reperfusion of the ischemic liver Peak I showed more severe damage to the organelle. These observations clearly demonstrated that ischemia reperfusion injury causes structural damage to peroxisomes. Interestingly ultrastructural examination of Peak II following ischemia showed evidence of perisomal proliferation with budding of existing peroxisomes and the presence of micro peroxisomes (changes similar to those noted under conditions leading to perisomal proliferation). However, peak II following reperfusion showed only damaged organelle. These observations underline the importance of peroxisomes in the response of the cell to ischemia-reperfusion injury.     

Reperfusion-induced arrhythmias are not prevented by ibuprofen in isolated rat heart

Free radicals have been implicated in the genesis of reperfusion-induced arrhythmias and the cyclooxygenase pathways has been suggested as a potential source. We have therefore assessed whether a cyclooxygenase inhibitor, ibuprofen, is able to reduce reperfusion-induced injury in the isolated perfused rat heart. A duration of 10 min of regional ischemia, which resulted in a high (83%) incidence of ventricular fibrillation, was selected and hearts (n = 12/group) were perfused with ibuprofen (2, 20, or 30 mg/L) throughout the experiment. Ibuprofen did not affect heart rate, although it did produce a dose-dependent increase in coronary flow. However, at all doses studied, ibuprofen had no effect upon the time to onset, incidence, or duration of arrhythmias. In subsequent studies with 30 min of regional ischemia, ibuprofen (30 mg/L) again caused vasodilatation but without effect upon heart rate or severity of arrhythmias. In conclusion, we were unable to obtain evidence in support of the concept that cyclooxygenase activity or cyclooxygenase-derived free radicals are involved in the genesis of ischemia- and reperfusion-induced arrhythmias.     

Liposome-entrapped superoxide dismutase reduces ischemia/reperfusion ‘oxidative stress’ in gerbil brain

Bilateral common carotid artery occlusion (15 min.) followed by two hours of recirculation reduced mitochondrial superoxide dismutase (SOD) and glutathione reductase (GR) activities, and increased susceptibility of mitochondrial membranes to in vitro lipid peroxidation in brain regions (i.e., cortex, striatum and hippocampus) of Mongolian gerbil. Intraperitoneal bolus injection (2 mg/kg b.w.) of liposome-entrapped CuZn superoxide dismutase (l-SOD) increased the endogenous SOD activity in normal brain tissue and, when given at the end of ischemia, counteracted both the ischemic reduction of endogenous SOD and the increased peroxidation of mitochondrial membranes. 1-SOD treatment was ineffective in reducing brain swelling, suggesting that superoxide radicals are not a main participant in the process of (post)ischemic brain edema formation.     

光化学法脑缺血后细胞凋亡及其相关基因bcl-2表达的变化

采用ＴＵＮＥＬ染色及免疫组织化学技术对光化学法脑缺血后细胞凋亡及其相关基因ｂｃｌ－２表达的变化进行了研究。结果发现，缺血后１２ｈ，损伤侧皮层缺血区内凋亡细胞数及ｂｃｌ－２免疫反应阳性细胞数明显增加，一直持续至缺血后７２ｈ；并呈现下列时程变化：在缺血后３ｈ每张切片上几乎无凋亡细胞出现，以后逐渐增加，缺血后１２ｈ达到峰值，缺血后２４ｈ和缺血后７２ｈ逐渐减少，但仍高于假手术组水平。凋亡相关基因ｂｃｌ－２的表达在缺血后３ｈ以前不明显，缺血后１２ｈ逐渐增加，缺血后２４ｈ最多，以后逐渐下降。上述结果提示，缺血后凋亡细胞的时程变化可能与缺血后梗塞灶的发生和发展有关，而ｂｃｌ－２表达的变化可能与抑制细胞凋亡、发挥内源性细胞保护作用有关。     

Protective effect of N-acetylcysteine (NAC) on renal ischemia/reperfusion injury through Nrf2 signaling pathway

Abstract

The aim of this study was to investigate whether N-acetylcysteine (NAC), a known antioxidant, can protect kidney against ischemic injury through regulating Nrf2 signaling pathway. The expression of Nrf2, HO-1 and cleaved caspase 3 were analyzed by Western blot analysis. Apoptosis of renal tubular epithelial cells was assessed by the TUNEL method. Malondialdehyde (MDA) levels were measured by the thiobarbituric acid reaction. Blood serum creatinine and blood urea nitrogen levels were measured with an Olympus automatic multi-analyzer. We found that NAC significantly increased Nrf2 and downstream HO-1 expression. Furthermore, NAC significantly decreased cleaved caspase 3, p53 and renal epithelial tubular cell apoptosis. In addition, NAC reduced the MDA level. These findings suggest that the protective action of NAC on ischemia renal injury is associated closely with Nrf2 signaling pathway.     

A comparative study on the antioxidant effects of hesperidin and ellagic acid against skeletal muscle ischemia/reperfusion injury

Abstract

The antioxidant effects of ellagic acid (EA) and hesperidin (HES) against skeletal muscle ischemia/reperfusion injury (I/R) were performed. Hindlimb ischemia has been induced by tourniquet occlusion for 2?h on left hindlimb. At the end of ischemia, the tourniquate has been removed and initiated reperfusion for 2?h. EA (100?mg/kg) has been applied orally before ischemia/reperfusion in the EA?+?I/R group. HES (100?mg/kg) has been given orally in the HES?+?I/R group. The left gastrocnemius muscle has been harvested and stored immediately at??80?°C until assessed for the levels of MDA and antioxidant enzymes activities. MDA level has statistically increased in I/R group (p?<?0.05) compared to other groups. The muscle tissue antioxidant enzymes activities were lower than the other groups in the I/R group (p?<?0.05). EA and HES treatments significantly reversed the damage level in I/R, also activity of tissue SOD increased in the EA?+?I/R and HES?+?I/R groups.     

Environmental factors affecting the distribution of aquatic invertebrates in temporary ponds in Mammoth Cave National Park,Kentucky, USA

Despite a recent surge of interest in temporary lentic systems, a strong theory linking the biota to its environment has not emerged. Using data from 10 temporary ponds at Mammoth Cave National Park, Kentucky, USA, we investigated how invertebrate communities were structured along environmental gradients, both between and within ponds. Samples were collected with a benthic corer in winter and spring, and a sweep net in spring. Six between-pond and two within-pond datasets were created. Between-pond analyses yielded significant CCA’s with only one of the six data sets. The ranges of environmental variables (EV’s) within ponds were often similar to the ranges of EV’s when averaged and compared between ponds. Some taxa were aggregated in a single pond, and richness increased with pond area. The theory that richness increases with hydroperiod did not apply to these systems. Within-pond analyses yielded more consistent relationships, with both CCA’s being significant. Sample depth was the best predictor of invertebrate richness and abundance, with most taxa preferring shallow habitats. Richness and abundance were higher in both shallow ponds and shallow areas of deep ponds than in deep areas of deep ponds. Standardizing sample depth may be an effective way to remove this gradient as a confounding variable in future research. The presence of within-pond gradients, possibly coupled with the limited dispersal and random colonization of tolerant taxa, makes between-pond comparisons difficult. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorised users. Handling editor: S. Declerck     

Effects of Fructose-1,6-Bisphosphate on Glutamate Release and ATP Loss from Rat Brain Slices During Hypoxia

Abstract: Fructose-1,6-bisphosphate (FBP), an intermediate of glucose metabolism, is neuroprotective in brain hypoxia or ischemia. Because the mechanisms for this protection are not clear, we examined the effects of FBP on two important events in brain ischemia, i.e., loss of ATP and release of the excitatory neurotransmitter glutamate. Glutamate release from cortical brain slices was measured fluorometrically (glutamate dehydrogenase)-catalyzed conversion of glutamate to α-ketoglutarate) during hypoxia (Po₂ 15 mm Hg) or hypoxia plus 100 µ M cyanide. FBP (3.5 m M , with glucose 20 m M ) reduced glutamate release during hypoxia by 55% and during hypoxia/cyanide by 46% ( p < 0.005), and prevented a significant fall in [ATP]. [ATP] was maintained in oxygenated glucose-free conditions with 20 but not 3.5 m M FBP, and fell to <20% of normal with hypoxia. Despite the drop in [ATP], 3.5 or 20 m M FBP without glucose decreased hypoxia-evoked glutamate release. We conclude (1) FBP present without glucose preserves normal [ATP] only when oxygen is available, suggesting limited uptake and metabolism; and (2) FBP decreases hypoxia-evoked glutamate release by processes independent of [ATP]. These results suggest protective actions of FBP that are separate from augmentation of anaerobic energy production, as previously proposed.