神经节苷脂GM1在缺血性脑血管病中的神经保护机制

神经节苷脂GM1在脑血管病中的作用日益受到重视。已有研究证明神经节苷脂GM1对脑缺血损伤有神经保护作用。文章就神经节苷脂GM1对缺血性脑血管病神经保护作用的机制作了综述。     

神经节苷脂GM1在缺血性脑血管病中的神经保护机制

神经节苷脂GM1在脑血管病中的作用日益受到重视。已有研究证明神经节苷脂GM1对脑缺血损伤有神经保护作用。文章就神经节苷脂GM1对缺血性脑血管病神经保护作用的机制作了综述。     

单唾液酸神经节苷脂与缺血性脑损伤

脑缺血后给予单唾液酸神经节苷脂(GM1)可有效地减轻急性神经细胞损害,促进中、后期神经功能恢复。GM1在急性损伤期的保护作用至少部分是由于其抗兴奋毒性作用,而GM1促进后期神经功能恢复的作用可能反映其神经营养性因子的效应。     

神经节苷脂钠治疗新生儿胆红素脑病临床疗效观察

目的观察应用神经节苷脂钠治疗新生儿胆红素脑病的疗效。方法选择新生儿胆红素脑病42例随机分为治疗组(22例)和对照组(20例)。两组均给予常规治疗,治疗组在常规治疗基础上急性期给予神经节苷脂钠(GM1)治疗,剂量20 mg/d,共治疗7 d(一个疗程)。观察两组治疗后的效果并对神经行为进行评分。结果治疗组的疗效明显优于对照组(P0.05),治疗后神经行为评分高于对照组(P0-01)。结论神经节苷脂钠治疗新生儿胆红素脑病可提高干预效果,减少后遗症的发生。     

神经节苷脂联合高压氧治疗一氧化碳中毒迟发性脑病35例疗效观察

一氧化碳中毒性迟发性脑病（DEACMP）患者以痴呆表现为主,可伴有精神和意识障碍、锥体及锥体外系症状等,重症患者可遗留严重后遗症而影响生活质量.目前DEACMP的发病机制尚不明确,缺乏切实有效的治疗和预防方法.高压氧疗法（HBO）在预防和治疗DEACMP方面均有较高的认知度和相对好的疗效.神经节苷脂广泛存在于神经系统中,可促进中枢神经系统的重塑,保护和营养神经.我们应用神经节苷脂联合高压氧治疗一氧化碳中毒性迟发性脑病,并对患者疗效进行评估,以探讨神经节苷脂在一氧化碳中毒性迟发性脑病患者治疗中的效果.     

神经节苷脂联合参附注射液对新生大鼠缺氧缺血性脑损伤的保护作用

目的探讨神经节苷脂(GM1)联合参附注射液对新生大鼠缺氧缺血性脑损伤(HIBD)的神经保护作用。方法将新生7d SD乳鼠90只随机分为假手术组、缺血缺氧组(HIBD组)、缺血缺氧+GM1干预组(GM1组)、缺血缺氧+参附干预组(参附组)及缺血缺氧+GM1及参附干预组(合用组)。在给药后不同时间点,采用免疫组化法半定量测定脑组织中Bcl-2及Bax含量。结果假手术组海马CA1区可见少量Bcl-2及Bax表达;HIBD后该区Bcl-2及Bax表达均增加,且Bax表达较明显;分别应用GM1、参附注射液治疗后该区Bcl-2表达进一步增加,而Bax蛋白水平下降;联合应用两种药物治疗后该区Bcl-2表达增加、Bax表达下降的趋势更为明显。结论新生大鼠脑缺氧缺血后腹腔注射神经节苷脂或参附注射液均可不同程度减轻大鼠脑损伤,两种药物联合应用对其脑损伤的改善作用更为明显。     

新生大鼠缺血缺氧后胶质性谷氨酸转运体的表达及GM1的干预研究

目的探讨新生大鼠缺血缺氧性脑损伤后胶质性谷氨酸转运体的表达及神经节苷脂（GM1）的干预作用。方法通过建立新生大鼠缺血缺氧性脑损伤动物模型，应用免疫组化方法，观察缺血缺氧后不同时期大脑皮质胶质性谷氨酸转运体EAATI、EAAT2的动态表达度GM1对其表达的影响。结果缺血缺氧后6hEAAT1的表达开始上升、第2d达高峰，第3d恢复到假手术组水平；EAAT2的表达在缺血缺氧后12h开始上升，第3d达高峰，第5d恢复到假手术组水平；GM1干预组脑组织损伤明显减轻，EAAT1和EAAT2的表达较单纯缺血缺氧组显著增加（P〈0．01），持续时间延长。结论缺血缺氧诱导胶质性谷氨酸转运体的表达，GM1提高胶质性谷氨酸转运体的表达可能是GM1脑保护作用的重要机制之一。     

国产单唾液酸四己糖神经节苷脂治疗老年急性脑梗死的疗效

单唾液酸四己糖神经节苷脂(monosialotetrahexosylganglioside,GM1 )是促进中枢神经系统损伤修复的一种新药,具有增强体内营养因子作用,减缓或中断周围神经髓鞘脱失,促进神经的生长和髓鞘的修复.GM主要分布在神经细胞膜,与神经重构(神经可塑性)的生理功能有关.     

神经节苷脂联合尼莫地平对脑缺血半暗带细胞凋亡及凋亡蛋白Bcl-2/Bax的影响

目的 观察神经节苷脂GM1联合尼莫地平治疗对大鼠脑缺血再灌注损伤后缺血半暗带神经细胞凋亡及凋亡相关蛋白Bcl-2/Bax的影响.方法 36只清洁级健康雄性SD大鼠随机分为假手术组、模型组、药物治疗组.线栓法制备大脑中动脉Bcl-2/Bax缺血再灌注模型(MCAO模型),缺血2 h再灌注6 h,12 h,24 h,72 h.采用TUNEL法检测神经细胞凋亡,免疫组织化学法染色检测Bcl-2、Bax蛋白,并进行统计学分析.结果 与模型组比较,药物治疗组神经细胞凋亡计数随再灌注时间的延长显著减少(P<0.05).药物治疗组随再灌注时间延长,缺血半暗带区Bcl-2表达逐渐增强、以及Bax表达逐渐减弱,缺血2 h再灌注12 h后,Bcl-2/Bax比值达到高峰,与模型组比较有统计学意义(P<0.05).结论 在脑缺血半暗带区,神经节苷脂联合尼莫地平干预治疗,通过上调Bcl-2表达,以及下调Bax表达,能够减少神经细胞凋亡,从而发挥神经细胞保护作用.     

神经节苷脂治疗急性脑出血60例的疗效分析

目的 评价神经节苷脂治疗急性脑出血的效果.方法 将急性脑出血患者120例分为两组.治疗组60例,给予神经节苷脂40～60mg加入0.9%氯化钠溶液250ml内静脉滴注,连续15d;对照组60例,给予胞磷胆碱治疗.治疗前、治疗终、2个月后对两组患者进行神经功能缺损程度及日常生活活动量评分,并进行比较.结果 GM1治疗组与对照组相比治疗终、治疗2个月后神经功能缺损程度评分、日常生活活动量评分均有极显著的差异(P均<0.01).结论 神经节苷脂治疗有明显的神经保护作用,能促进神经功能的早期恢复,降低致残率.     

Interruption of ganglioside synthesis produces central nervous system degeneration and altered axon-glial interactions

Gangliosides, which are sialylated glycosphingolipids, are the major class of glycoconjugates on neurons and carry the majority of the sialic acid within the central nervous system (CNS). To determine the role of ganglioside synthesis within the CNS, mice carrying null mutations in two critical ganglioside-specific glycosyltransferase genes, Siat9 (encoding GM3 synthase) and Galgt1 (encoding GM2 synthase), were generated. These double-null mice were unable to synthesize gangliosides of the ganglio-series of glycosphingolipids, which are the major ganglioside class in the CNS. Soon after weaning, viable mice developed a severe neurodegenerative disease that resulted in death. Histopathological examination revealed striking vacuolar pathology in the white matter regions of the CNS with axonal degeneration and perturbed axon-glia interactions. These results indicate that ganglioside synthesis is essential for the development of a stable CNS, possibly by means of the promotion of interactions between axon and glia.     

Glycosphingolipid storage leads to the enhanced degradation of the B cell receptor in Sandhoff disease mice

Glycosphingolipid storage diseases are a group of inherited metabolic diseases in which glycosphingolipids accumulate due to their impaired lysosomal breakdown. Splenic B cells isolated from NPC1, Sandhoff, GM1-gangliosidosis and Fabry disease mouse models showed large (20- to 30-fold) increases in disease specific glycosphingolipids and up to a 4-fold increase in cholesterol. The magnitude of glycosphingolipid storage was in the order NPC1 > Sandhoff ∼ GM1 gangliosidosis > Fabry. Except for Fabry disease, glycosphingolipid storage led to an increase in the lysosomal compartment and altered glycosphingolipid trafficking. In order to investigate the consequences of storage on B cell function, the levels of surface expression of B cell IgM receptor and its associated components were quantitated in Sandhoff B cells, since they are all raft-associated on activation. Both the B cell receptor, CD21 and CD19 had decreased cell surface expression. In contrast, CD40 and MHC II, surface receptors that do not associate with lipid rafts, were unchanged. Using a pulse chase biotinylation procedure, surface B cell receptors on a Sandhoff lymphoblast cell line were found to have a significantly decreased half-life. Increased co-localization of fluorescently conjugated cholera toxin and lysosomes was also observed in Sandhoff B cells. Glycosphingolipid storage leads to the enhanced formation of lysosomal lipid rafts, altered endocytic trafficking and increased degradation of the B cell receptor.     

Ability of blood group A-active glycosphingolipids to act as Escherichia coli heat-labile enterotoxin receptors in HT-29 cells

We examined the ability of blood group A-active glycoconjugates to act as receptors for Escherichia coli heat-labile type I enterotoxin (LT-I) in HT-29 cells. These cells contained ~4 times more specific binding sites for LT-I than for cholera toxin (CT). Binding of LT-I could not be blocked by the B subunit of CT (CT-B), indicating the existence of LT-I receptors in addition to the glycosphingolipid GM1. LT-I was able to increase levels of cyclic adenosine monophosphate (AMP), even in the presence of CT-B. Helix pomatia and anti-blood group A antibody caused a dose-dependent inhibition of binding of LT-I to cells and production of cyclic AMP. LT-I recognized several complex blood group A-active glycosphingolipids from cells, and this interaction was also interfered with by H. pomatia. Treatment of cells with D,L-threo-1-phenyl-2-hexadecanoylamino-3-morpholino-1-propanol diminished surface expression of blood group A-active glycosphingolipids and binding of LT-I to non-GM1 receptors. These observations suggest that blood group A-active glycosphingolipids can function as alternative receptors for LT-I in HT-29 cells.     

Enhanced insulin sensitivity in mice lacking ganglioside GM3

Gangliosides are sialic acid-containing glycosphingolipids that are present on all mammalian plasma membranes where they participate in recognition and signaling activities. We have established mutant mice that lack GM3 synthase (CMP-NeuAc:lactosylceramide alpha2,3-sialyltransferase; EC 2.4.99.-). These mutant mice were unable to synthesize GM3 ganglioside, a simple and widely distributed glycosphingolipid. The mutant mice were viable and appeared without major abnormalities but showed a heightened sensitivity to insulin. A basis for the increased insulin sensitivity in the mutant mice was found to be enhanced insulin receptor phosphorylation in skeletal muscle. Importantly, the mutant mice were protected from high-fat diet-induced insulin resistance. Our results show that GM3 ganglioside is a negative regulator of insulin signaling, making it a potential therapeutic target in type 2 diabetes.     

Ectopic dendrites occur only on cortical pyramidal cells containing elevated GM2 ganglioside in alpha-mannosidosis.

In a variety of neuronal storage diseases, cortical pyramidal cells elaborate ectopic dendrites at the axon hillock. A feature common to all the diseases characterized by ectopic dendrites is an elevated level of GM2 ganglioside in cerebral cortex. In cats with one such disease, alpha-mannosidosis, the number of pyramidal cells bearing ectopic dendrites is small; the present study shows that GM2 ganglioside is stored only in those pyramidal neurons exhibiting ectopic dendrites. Using a Golgi-electron microscopy method with periodic acid-Schiff (PAS) staining, we first established that pyramidal cells bearing ectopic dendrites contained PAS+ membranous inclusions, consistent with storage of glycolipids. In contrast, those with smooth axon hillocks accumulated PAS- floccular inclusions, consistent with storage of oligosaccharides. Next, application of a monoclonal antibody against GM2 ganglioside revealed that subsets of both pyramidal and intrinsic neurons contained GM2-like immunoreactivity. Every GM2+ cell contained PAS+ membranous inclusions, indicating that pyramidal cells bearing ectopic dendrites stored GM2 ganglioside. In cats with alpha-mannosidosis induced by swainsonine, some pyramidal neurons showed GM2-like immunoreactivity after 4 weeks of treatment, whereas ectopic dendrites only became evident after 7 weeks of treatment. Thus, GM2 ganglioside accumulated in pyramidal neurons before ectopic dendrites emerged from the axon hillock. We propose that the reinitiation of dendrite growth on mature pyramidal cells is brought about by accumulated GM2 ganglioside.     

The possible contribution of a general glycosphingolipid transporter, GM2 activator protein, to atherosclerosis

We previously found that oxidized low-density lipoprotein (LDL) elevated the expression of mRNA of GalNAcbeta1-4[NeuNAcalpha2-3]Galbeta1-4Glc-Cer (GM2) ganglioside activator protein, in human monocyte-derived macrophages. Recently, GM2 activator protein has become known as a general glycosphingolipid transporter as well as a specific cofactor for the hydrolysis of GM2 ganglioside by lysosomal beta-hexosaminidase A. Accumulation of glycosphingolipids has been observed in the serum or aorta of atherosclerotic model animals and humans. The proliferation of aortic smooth muscle cells, elevation of LDL uptake by macrophages, interfering LDL clearance by the liver, and enhancement of platelet adhesion to collagen have been proposed as the underlying mechanisms of glycosphingolipid-mediated atherogenesis. The GM2 activator protein can bind, solubilize and transport a broad spectrum of lipid molecules, indicating that GM2 activator protein may function as a general intra- and inter-cellular lipid transport protein. Collectively, elevated levels of GM2 activator protein in the aorta may be another feature of human atherosclerosis.     

Glycosphingolipid degradation and animal models of GM2-gangliosidoses

Glycosphingolipids form cell type-specific patterns on the surface of eukaryotic cells. Degradation of glycosphingolipids requires endocytic membrane flow of plasma membrane-derived glycosphingolipids into the lysosomes as the digesting organelles. The inherited deficiencies of lysosomal hydrolases and of sphingolipid activator proteins both give rise to sphingolipid storage diseases. Recent research has focused on the mechanisms leading to selective membrane degradation in the lysosomes and on the mechanism and physiological function of sphingolipid activator proteins. The GM2-degrading system is a paradigm for activator protein-dependent lysosomal degradation. Three polypeptide chains contribute to the in vivo degradation of ganglioside GM2: the - and -chains of the -hexosaminidases and the GM2 activator. Mouse models of Tay–Sachs disease (-chain deficiency), Sandhoff disease (-chain deficiency) and GM2 activator deficiency have been described. While the phenotypes of these variants of GM2-gangliosidoses are only slightly different in humans, the animal models show drastic differences in severity and course of the diseases. The reason for this is the specificity of sialidase, which is different between mouse and human. A double-knockout mouse lacking -hexosaminidases A, B and S shows a phenotype of mucopolysaccharidosis and gangliosidosis. A substrate deprivation approach to therapy is discussed with respect to animal models of the GM2-gangliosidoses.     

Childhood rare lung disease in the 21st century: “‐omics” technology advances accelerating discovery

Childhood rare lung diseases comprise a large number of heterogeneous respiratory disorders that are individually rare but are collectively associated with substantial morbidity, mortality, and healthcare resource utilization. Although the genetic mechanisms for several of these disorders have been elucidated, the pathogenesis mechanisms for others remain poorly understood and treatment options remain limited. Childhood rare lung diseases are enriched for genetic etiologies; identification of the disease mechanisms underlying these rare disorders can inform the biology of normal human lung development and has implications for the treatment of more common respiratory diseases in children and adults. Advances in “‐omics” technology, such as genomic sequencing, clinical phenotyping, biomarker discovery, genome editing, in vitro and model organism disease modeling, single‐cell analyses, cellular imaging, and high‐throughput drug screening have enabled significant progress for diagnosis and treatment of rare childhood lung diseases. The most striking example of this progress has been realized for patients with cystic fibrosis for whom effective, personalized therapies based on CFTR genotype are now available. In this chapter, we focus on recent technology advances in childhood rare lung diseases, acknowledge persistent challenges, and identify promising new technologies that will impact not only biological discovery, but also improve diagnosis, therapies, and survival for children with these rare disorders.     

Activation state and intracellular trafficking contribute to the repertoire of endogenous glycosphingolipids presented by CD1d

Myeloid antigen-presenting cells (APC) express CD1d molecules that present exogenous and endogenous lipid antigens that activate CD1d-restricted T cells, natural killer T (NKT) cells. NKT cell activation has been shown to mediate the potent downstream activation of other immune cells through cell–cell interactions and rapid, prolific cytokine production. Foreign antigens are not required for NKT cell activation. The endogenous lipids bound to CD1d are sufficient for activation of NKT cells in the setting of Toll-like receptor-induced cytokines. The most potent NKT cell antigens identified are glycosphingolipids (GSL). The GSL repertoire of endogenous ligands bound to CD1d molecules that are expressed in myeloid APC at steady state and in the setting of activation has not been delineated. This report identifies the range of GSL bound to soluble murine CD1d (mCD1d) molecules that sample the endoplasmic reticulum/secretory routes and cell surface-cleaved mCD1d that also samples the endocytic system. Specific GSL species are preferentially bound by mCD1d and do not solely reflect cellular GSL. GM1a and GD1a are prominent CD1d ligands for molecules following both the ER/secretory and lysosomal trafficking routes, whereas GM2 was eluted from soluble CD1d but not lysosomal trafficking CD1d. Further, after LPS activation, the quantities of soluble CD1d-bound GM3 and GM1a markedly increased. A unique α-galactose-terminating GSL was also found to be preferentially bound to mCD1d at steady state, and it increased with APC activation. Together, these studies identify the range of GSL presented by CD1d and how presentation varies based on CD1d intracellular trafficking and microbial activation.     

Review of Medicinal Plants and Active Pharmaceutical Ingredients against Aquatic Pathogenic Viruses

Aquaculture offers a promising source of economic and healthy protein for human consumption, which can improve wellbeing. Viral diseases are the most serious type of diseases affecting aquatic animals and a major obstacle to the development of the aquaculture industry. In the background of antibiotic-free farming, the development and application of antibiotic alternatives has become one of the most important issues in aquaculture. In recent years, many medicinal plants and their active pharmaceutical ingredients have been found to be effective in the treatment and prevention of viral diseases in aquatic animals. Compared with chemical drugs and antibiotics, medicinal plants have fewer side-effects, produce little drug resistance, and exhibit low toxicity to the water environment. Most medicinal plants can effectively improve the growth performance of aquatic animals; thus, they are becoming increasingly valued and widely used in aquaculture. The present review summarizes the promising antiviral activities of medicinal plants and their active pharmaceutical ingredients against aquatic viruses. Furthermore, it also explains their possible mechanisms of action and possible implications in the prevention or treatment of viral diseases in aquaculture. This article could lay the foundation for the future development of harmless drugs for the prevention and control of viral disease outbreaks in aquaculture.