Glutathione metabolism is modulated by postmortem interval, gender difference and agonal state in postmortem human brains

The equilibrium between antioxidant function and oxidative stress is implicated in brain pathology. However, human studies on oxidant and antioxidant markers rely on postmortem tissue that might be affected by pre and postmortem factors. To evaluate the effect of these variables, we tested whether antioxidant enzymes [superoxide dismutase (SOD), catalase] glutathione (GSH) and related enzymes [gamma glutamylcysteine ligase (GCL), GSH peroxidase (GPx), GSH reductase (GR), GSH-S-transferase (GST)] and malondialdehyde (MDA, marker of lipid peroxidation) are affected in postmortem human brains (n = 50) by increase in postmortem interval (2.5–26 h), gender difference and agonal state [based on Glasgow coma scale (GCS): range: 3–15] in different anatomical regions-frontal cortex (FC), cerebellum (CB) medulla oblongata (MO), substantia nigra (SN) and hippocampus (HC). While SOD and catalase activities were relatively unaltered, GR and GPx activities were affected by agonal state (GR in CB, p < 0.05; GPx in MO, p < 0.05) indicating altered GSH dynamics during the secondary events following neuronal injury. MO, SN and HC displayed low GSH compared to FC and CB. Total GSH level was decreased with PMI (MO, p = 0.02) which could be partly attributed to increase in MDA levels with increasing PMI in MO (p < 0.05). Total GSH level was higher in CB (p < 0.017) and MO (p < 0.04) in female brains compared to males. Interestingly, HC and SN regions showed significant stability in most of the markers tested. We suggest that while SOD and catalase were relatively unaffected by the pre and postmortem factors, GSH and its metabolic enzymes were significantly altered and this was more pronounced in MO of postmortem human brains. These data highlight the influence of pre and postmortem factors on GSH dynamics and the inherent differences in brain regions, with implications for studies on brain pathophysiology employing human samples.     

3-Ketone-4,6-diene ceramide analogs exclusively induce apoptosis in chemo-resistant cancer cells

Multidrug-resistance is a major cause of cancer chemotherapy failure in clinical treatment. Evidence shows that multidrug-resistant cancer cells are as sensitive as corresponding regular cancer cells under the exposure to anticancer ceramide analogs. In this work we designed five new ceramide analogs with different backbones, in order to test the hypothesis that extending the conjugated system in ceramide analogs would lead to an increase of their anticancer activity and selectivity towards resistant cancer cells. The analogs with the 3-ketone-4,6-diene backbone show the highest apoptosis-inducing efficacy. The most potent compound, analog 406, possesses higher pro-apoptotic activity in chemo-resistant cell lines MCF-7TN-R and NCI/ADR-RES than the corresponding chemo-sensitive cell lines MCF-7 and OVCAR-8, respectively. However, this compound shows the same potency in inhibiting the growth of another pair of chemo-sensitive and chemo-resistant cancer cells, MCF-7 and MCF-7/Dox. Mechanism investigations indicate that analog 406 can induce apoptosis in chemo-resistant cancer cells through the mitochondrial pathway. Cellular glucosylceramide synthase assay shows that analog 406 does not interrupt glucosylceramide synthase in chemo-resistant cancer cell NCI/ADR-RES. These findings suggest that due to certain intrinsic properties, ceramide analogs’ pro-apoptotic activity is not disrupted by the normal drug-resistance mechanisms, leading to their potential use for overcoming cancer multidrug-resistance.     

3,3′-Diindolylmethane but not indole-3-carbinol activates Nrf2 and induces Nrf2 target gene expression in cultured murine fibroblasts

Abstract

There is increasing interest in the gene-regulatory activity of Brassica vegetable derived phytochemicals such as 3,3′-diindolylmethane (DIM) and indole-3-carbinol (I3C). DIM is formed under acidic conditions by dimerization of I3C. This study compared the Nrf2 activating potential of DIM and I3C in murine fibroblasts (NIH3T3). In contrast to its precursor I3C, DIM induces the transactivation of Nrf2. Furthermore, Nrf2 targets such as HO-1, γGCS and NQO1 were increased on the mRNA and protein levels following DIM treatment. DIM was less potent than sulforaphane (used as positive control) in inducing Nrf2-dependent gene expression. The present data suggest that the dimerization of I3C to DIM increases its Nrf2 inducing activity.     

Gamete membrane dynamics during double fertilization in Arabidopsis

In the double fertilization of angiosperms, one sperm cell fertilizes an egg cell to produce a zygote, whereas the other sperm cell fertilizes a central cell to give rise to an endosperm. There is little information on gamete membrane dynamics during double fertilization even though the cell surface structure is critical for male and female gamete interactions. In a recent study, we analyzed gamete membrane behavior during double fertilization by live-cell imaging with Arabidopsis gamete membrane marker lines. We observed that the sperm membrane signals occasionally remained at the boundary of the female gametes after gamete fusion. In addition, sperm membrane signals entering the fertilized female gametes were detected. These findings suggested that plasma membrane fusion between male and female gametes occurred with the sperm internal membrane components entering the female gametes, and this was followed by plasmogamy.     

Modulation of ceramide metabolism in mouse primary macrophages

Ceramide kinase (CERK) produces the bioactive lipid ceramide 1-phosphate (C1P) and is, together with glucosylceramide synthase (GCS) and sphingomyelin synthases (SMS-1 and -2), a key regulator of ceramide metabolism. Here, we used a previously validated assay for measuring CERK, GCS, and SMS activities simultaneously, to study the regulation of ceramide metabolism in mouse macrophages. Elicitation of peritoneal macrophages as well as differentiation of bone marrow-derived monocytes into macrophages led to “ceramide anabolic switching” by re-directing ceramide anabolism towards C1P synthesis by CERK. In contrast, macrophage activation by lipopolysaccharide (LPS) evoked a “ceramide anabolic switch” going in the opposite direction, i.e. featuring up-regulation of GCS and SMS and down-regulation of CERK. The LPS effects were partially blocked by dexamethasone, a known macrophage de-activator. Altogether, the data reveal a contrasting regulation of ceramide metabolism enzymes during macrophage biological responses.     

Adaptation to acrolein through upregulating the protection by glutathione in human bronchial epithelial cells: The materialization of the hormesis concept

Acrolein is a thiol reactive compound present in cigarette smoke and plays a pivotal role in the deleterious effects of smoking. Acrolein causes toxicity in human bronchial epithelial cells in a dose dependent manner. GSH forms the first line of defense against acrolein-induced toxicity. At high doses of acrolein (?10 μM) the capacity of the cellular protection by GSH is overwhelmed and GSH is not able to quench all the acrolein, resulting in cytotoxicity.     

孕酮对外伤性蛛网膜下腔出血患者早期MMP-9水平及微循环的影响

目的:探究孕酮对外伤性蛛网膜下腔出血患者早期MMP-9水平及微循环的影响。方法:收集我院神经外科收治的外伤性蛛网膜下腔出血患者70例,根据随机数字对照表分为对照组(35例)与试验组(35例)。两组均给予常规治疗,对照组患者给予静脉注射尼莫地平治疗,试验组在此基础上给予复方甲地孕酮治疗。观察并比较两组患者治疗前后格拉斯哥昏迷指数GCS评分、金属基质蛋白酶-9(MMP9)水平及微循环的变化情况。结果:两组患者入院时GCS评分、血清MMP-9水平无明显差异(P0.05),对照组治疗14天后GCS评分明显升高(P0.05),而试验组治疗7天、14天后均明显升高(P0.05),且试验组治疗7天、14天后GCS评分较对照组评分高(P0.05);两组患者治疗7天后血清MMP-9水平降低(P0.05),且试验组血清MMP-9水平较对照组降低(P0.05);两组患者治疗后微循环均有所改善,伤测大脑中动脉收缩峰流速降低(P0.05),试验组改善更为明显,伤测大脑中动脉收缩峰流速降低更为显著(P0.05)。结论:孕酮对外伤性蛛网膜下腔出血患者的治疗效果明显,可能与其改善微循环,降低血清MMP-9水平有关。     

Enhanced ceramide-induced apoptosis in ceramide kinase overexpressing cells

We evaluated how increased levels of ceramide kinase (CerK) would impact the growth of COS-1 fibroblasts and RBL-2H3 basophils. The low CerK activity in these cells was strongly up-regulated upon recombinant expression of CerK. CerK-overexpressing COS-1 cells depended on higher concentrations of serum for their growth and displayed many filipodia. The two CerK-overexpressing cell lines were more sensitive to C2-ceramide-mediated apoptosis, and this correlated with the production of C2-ceramide-1-phosphate by CerK. This study indicates that ceramide kinase may participate in the control of cell growth, and establishes a novel assay that will be valuable for testing ceramide kinase inhibitors.