分泌型磷脂酶PLA2G5的生物学功能及其抑制剂研究进展

分泌型磷脂酶PLA2G5属于磷脂酶A2超家族的一员,在免疫细胞和非免疫细胞中均有表达.研究表明,PLA2G5参与生物学事件的发生发展,在特定的病理条件下具有诱导作用.本文简要阐述了PLA2G5的来源、结构特征、生物学功能和在疾病中的作用,以及现有或潜在的PLA2G5抑制剂,以期探索基于PLA2G5的治疗新靶标.     

Production of recombinant proteins by baculovirus-infected gypsy moth cells.

An experimental study was undertaken to evaluate alternative insect cell lines to Sf9 [from Spodoptera frugiperda (fall armyworm)] for the production of recombinant proteins. Insect cell lines from two different organisms were considered: IPLB-LdEIta (LdEIta) from Lymantria dispar (gypsy moth) and IPLB-HvT1 (HvT1) from Heliothis virescens (tobacco budworm). Both LdEIta and HvT1 produced higher total activity levels of recombinant beta-galactosidase in monolayer culture than Sf9 after infection with the Autographa californica nuclear polyhedrosis virus (AcMNPV). However, only LdEIta generated a product yield (activity per milligram of total protein) which exceeded that of Sf9 (by 25%), so its growth and production characteristics were investigated in depth. LdEIta generated production levels and yields of a recombinant rotaviral protein, VP4, which exceeded those of Sf9 by 84 and 38%, respectively. In suspension culture, the LdEIta cells grew as aggregates with a doubling time several hours longer than Sf9, but the recombinant product yields of LdEIta were still higher than Sf9 by 38% in this culture environment. beta-Galactosidase expression rates and cell death rates suggested that the difference in productivity between the two hosts was due to the ability of LdEIta to survive the baculovirus infection and produce recombinant proteins longer than Sf9. The presence of LdEIta aggregates in suspension culture may be used as a method to separate live cells from dead cells, labile product, and spent medium in recombinant protein production processes.     

A simple approach for the distribution of computationally intense tasks in an heterogeneous environment: distribution of the MDPP image-processing package

A method has been developed to link the display ability of ahigh-resolution graphics workstation with the computationalpower of a local mainframe or a remote supercomputer via anelectronic data network. The method allows this link to be establishedin a manner largely transparent to the user. The applicationof the method is illustrated by our successful distributionof the computationally intensive portions of an imaging program(MDPP) from a small VAX workstation to a VAX mainframe and CrayY-MP8/832 using a simple message-passing technique. This techniquecan be applied to almost any configuration of networked machines. Received on February 5, 1991; accepted on April 23, 1991     

人体动脉血气波浪式变化特点的实验证据—同时间动、静脉血波浪式变化幅度的不同*

目的: 人动脉血来源是右心系统并在肺脏进行气体交换的静脉血,右心系统的静脉血是否存在波浪式信号目前尚没有证据支持,本研究旨在对比同时间动、静脉血中信号的连续变化特点。方法: 选择心功能正常,需要连续监测动脉血流动力学变化的患者6 例,4男2女,年龄（59.00±16.64） 岁,体质量（71.67±10.37）kg,左心射血分数（LVEF）（61.33±2.16)%。患者签署知情同意书后,选择心功能正常需要监测动、静脉血流动力学变化的患者6 例,连续同时桡动脉、颈内静脉逐搏取血,测定PaO₂。选取2个典型呼吸周期,用于分析同时段动、静脉血气的波浪式变化。分别比较患者血氧分压最高和最低值,以验证同时段动、静脉血气是否都存在周期性波浪式信号变化。此外,将患者动脉、静脉血气周期性波浪式信号的变化幅度进行统计学t 检验分析,比较有无差异。结果: 共6例患者,抽取动、静脉血液充满肝素化细长塑化管需要15~16次心跳,即取血需要15~16次心跳,全部覆盖超过2个呼吸周期。所有患者动脉血气中PaO₂均呈现明显的波浪式变化（P<0.05）,幅度是（9.96±5.18）mmHg,是均值的（8.09±2.43）%。患者静脉血气中PaO₂波动幅度并不明显,为（1.63±0.41）mmHg,是均值的（3.91±1.22）%,与动脉血气组相比有明显统计学差异（P<0.05）。结论: 采用同时连续逐搏动、静脉取血血气分析法证实,患者自主呼吸时动脉血气有明显的周期性波浪式变化信号,而静脉血气几乎没有周期性波浪式变化信号（很弱）,说明动脉血气波浪式信号主要是由于肺通气过程中吸气和呼气期产生肺泡中氧分压规律性上升和下降,通过离开肺毛细血管与肺泡氧气压力平衡的动脉化血液,经过左心室搏血进入动脉血管系统所致。     

新生儿首次呼吸前后脐带动静脉血液氧和二氧化碳变化探索呼吸调控机制的初步报告II—同一个新生儿同一时间的脐带动静脉血液氧和二氧化碳分压差值个体化分析*

目的: 为探讨新生儿自主呼吸产生机制,前文已对新生儿出生后自主呼吸开始前脐带动静脉氧气和二氧化碳差值进行了人群组间分析;而本部分则对相关信息进行个体化分析。方法: 在产前经所有胎儿父母签署知情同意书,新生儿出生后还没有呼吸之前在脐带动脉和脐带静脉分别连续逐搏取血,仅有3例同时采集到Pua和Puv血液样本进行血气分析测定,计算分析脐带静脉和脐带动脉的异同和动态变化。结果: 虽然准备了数十产妇,但仅有3例同时采集到Pua和Puv血液样本,同一时间的PuvO₂显著高于PuaO₂（P均<0.01）,平均相差（24.17±7.09） mmHg;而PuvCO₂显著低于PuaCO₂（P均<0.01）,平均相差（-7.67±3.70） mmHg。在同一时间的Puv-uaO₂显著高于Puv-uaCO₂（P<0.05）。结论: 新生儿出生后自主呼吸前,全部氧气供应由脐带静脉运输,只要胎盘开始剥离则新生儿的PuaO₂随时间（心跳次数）逐渐降低,当PuaO₂达到触发呼吸阈值（最低值）诱发第一次吸气开始其自主呼吸。     

Alteration of surfactant protein A expression in renal cell carcinoma

Surfactant protein-A (SP-A) belongs to a family of collagen-containing C-type lectins called collectins. SP-A is expressed by renal tubule epithelial cells. We investigated the distribution of SP-A in renal cell carcinomas (RCC) using immunohistochemical techniques and western blotting. We used 35 formalin fixed, paraffin embedded (FFPE) RCC tissue samples. We compared results with clinico-pathological parameters of RCC including age, sex, Fuhrman grade, tumor volume, tumor node metastasis (TNM) and clinical stage. SP-A was localized in the glomerulus and renal tubule epithelium in nontumor tissue and strong SP-A immunoreactivity was observed in tumor tissue. SP-A was expressed in the RCC tumor cells (64%) and nontumor cells (34%) in males and RCC tumor cells (90%) and nontumor cells (30%) in females. There was a significant correlation between SP-A immunoreactivity in tumor cells and gender, age, tumor diameter, Fuhrman grade and tumor diameter. Western blot analysis supported the immunohistochemical findings. We present evidence for involvement of SP-A in RCC and suggest that increased SP-A expression in RCC is associated with favorable prognosis.     

Predation drives stable coexistence ratios between red and green pea aphid morphs

We conducted field surveys and experiments to evaluate the hypothesis that predation is an important driving factor determining the degree of coexistence between red and green morphs of the pea aphid Acyrthosiphon pisum. Theory suggests that the different colour morphs are differentially susceptible to natural enemies and selection by predation which in turn leads to variable relative abundances of red and green morphs among host plants across landscapes. Our field surveys on pea and alfalfa revealed, however, that the colour morphs tended to coexist closely in a ratio of one red to three green aphids across fields with different host plant monocultures. Experimentation involving manipulation of the relative abundances of the two colour morphs on host plants pea and alfalfa with and without predator presence revealed that red morphs had higher or same fitness (per capita reproduction) than green morphs on both pea and alfalfa only when in the proportion of one red/three green proportion. Moreover, experimentation evaluating predator efficiency revealed that red morphs are safest from predation when in a 1 : 3 ratio with green morphs. These results suggest that in addition to predation selection effects, red morphs may behaviourally choose to associate with green morphs in a narrow 1 : 3 ratio to maximize their fitness. This evidence, along with existing published data on red and green morph anti‐predator behaviour indicates that a 1 : 3 red and green morph coexistence ratio is driven by a balance between predation pressure and behavioural assorting by red morphs across landscapes. In this way predators may have ecological‐evolutionary consequences for traits that affect the colour morphs' proportion and tolerances to selective pressure.     

Investigations on Aberrant Glycosylation of Glycosphingolipids in Colorectal Cancer Tissues Using Liquid Chromatography and Matrix-Assisted Laser Desorption Time-of-Flight Mass Spectrometry (MALDI-TOF-MS)

Cancer is a leading cause of death and alterations of glycosylation are characteristic features of malignant cells. Colorectal cancer is one of the most common cancers and its exact causes and biology are not yet well understood. Here, we compared glycosylation profiles of colorectal tumor tissues and corresponding control tissues of 13 colorectal cancer patients to contribute to the understanding of this cancer. Using MALDI-TOF(/TOF)-MS and 2-dimensional LC-MS/MS we characterized enzymatically released and 2-aminobenzoic acid labeled glycans from glycosphingolipids. Multivariate data analysis revealed significant differences between tumor and corresponding control tissues. Main discriminators were obtained, which represent the overall alteration in glycosylation of glycosphingolipids during colorectal cancer progression, and these were found to be characterized by (1) increased fucosylation, (2) decreased acetylation, (3) decreased sulfation, (4) reduced expression of globo-type glycans, as well as (5) disialyl gangliosides. The findings of our current research confirm former reports, and in addition expand the knowledge of glycosphingolipid glycosylation in colorectal cancer by revealing new glycans with discriminative power and characteristic, cancer-associated glycosylation alterations. The obtained discriminating glycans can contribute to progress the discovery of biomarkers to improve diagnostics and patient treatment.Worldwide, cancer is a leading cause of death. With estimated 1.2 million diagnoses in 2008, colorectal cancer is the third most common cancer in the world and the fourth most common cause of death with an annual mortality of ∼600 000 (1). The exact causes of colorectal cancer are unknown, but different risk factors such as age, polyps, personal and family history, ulcerative colitis, or Crohn''s colitis have been proposed (2). Standard screening procedures include flexible sigmoidoscopy, colonoscopy, and immunological fecal occult blood testing. Each of them has its advantages and drawbacks such as invasiveness or low sensitivity and specificity (3). The method of choice for the treatment of colorectal cancer is surgery and therapeutic decisions are based on the tumor, lymph node, and metastasis staging-system as a prognostic factor (4). Current research has led to improved treatment strategies of colorectal cancer, however, the clinical outcome, the progression of the disease, and the response to the treatment remain variable among individuals. The heterogeneity of colorectal cancer at the molecular level—caused by accumulation of multiple genetic changes—may be one of the main reasons for this variability (5). Genetic factors such as instabilities, but also expression levels (6) can explain part of the cancer biology, but glycomics is gaining importance to complement the overall picture as aberrant glycosylation of proteins and lipids has been shown to be correlated with disease and malignancy (7, 8).Glycosylation is involved in many biological processes and especially its functional role in cellular interaction with respect to adhesion, cell growth, and signaling is prone to be affected in cancer progression, invasion, and metastasis (9). Several cancer-associated alterations in protein glycosylation have been reported: (1) increased branching of N-glycans, (2) higher density of O-glycans, and (3) incomplete synthesis of glycans. More particularly, an increased or induced expression of GlcNAc transferase V resulting in N-glycan structures with β1–6GlcNAc antennae (5, 10), and the expression of (sialyl) Tn-antigens (11) as aberrant O-glycosylation have been reported (10).Altered glycosphingolipid (GSL)¹ glycosylation of the cell surface membrane during malignancy can affect cell recognition, adhesion, and signal transduction (12) and is found to reflect: (1) incomplete synthesis with or without precursor accumulation, (2) neosynthesis (9), (3) increased sialylation, and (4) increased fucosylation (13). In many cancers, including colorectal cancer, an overexpression of the (sialyl) Lewis X antigen (10, 14) and the expression of (sialyl) Lewis A (15) are considered to be related to malignant transformation—reflecting incomplete synthesis of sialyl 6-sulfo Lewis X and disialyl Lewis A (16) as well as neosynthesis (17). Studies on gangliosides showed an overexpression of these sialylated GSLs in human malignant melanoma (18). Furthermore, the involvement of gangliosides in cell adhesion and motility was reported, which contributes to tumor metastasis (19). Specifically, the gangliosides GD3 (Hex2NeuAc2ceramide) and GM2 (Hex2HexNAc1NeuAc1ceramide) have been found to be associated with tumor-angiogenesis (19). The up-regulation of fucosyltransferases in cancer was shown to cause a higher degree of fucosylation in malignant tissues (20) and Moriwaki et al. proposed that the increase in the fucosylation for GSLs was an early event in cancer (21). Misonou et al. investigated glycans derived from GSLs in colorectal cancer tissues showing aberrant glycan structures based on linkage differences as well as increased sialylation and fucosylation compared with control tissue (22), which is in line with observed changes in GSL glycosylation with regard to cancer progression (9, 13).Recently, we investigated the N-glycosylation profiles of colorectal tumors and correlating control tissues for biomarker discovery. Statistical analyses revealed an increase of sulfated glycan structures as well as paucimannosidic glycans and glycans containing sialylated Lewis type epitopes in the tumor tissue, whereas structures with bisecting GlcNAc were found to be decreased in malignancy (23). To further progress the understanding of colorectal cancer biology and the improvement of diagnostic tools and patient treatment, we complemented this recent study on N-glycosylation by an investigation of the glycosphingolipid-derived glycans (named GSL-glycans in the following) from frozen tumor tissues and corresponding control tissues from the same 13 colorectal cancer patients. GSL-glycans were enzymatically released, labeled with 2-aminobenzoic acid (AA) and analyzed by hydrophilic interaction liquid chromatography (HILIC) with fluorescence detection as well as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Employing multivariate statistical analysis, this approach revealed an intricate GSL-glycosylation pattern of tumor tissues and specific glycosylation differences in comparison to the corresponding control tissue.     

The FSHD2 Gene SMCHD1 Is a Modifier of Disease Severity in Families Affected by FSHD1

Facioscapulohumeral muscular dystrophy type 1 (FSHD1) is caused by contraction of the D4Z4 repeat array on chromosome 4 to a size of 1–10 units. The residual number of D4Z4 units inversely correlates with clinical severity, but significant clinical variability exists. Each unit contains a copy of the DUX4 retrogene. Repeat contractions are associated with changes in D4Z4 chromatin structure that increase the likelihood of DUX4 expression in skeletal muscle, but only when the repeat resides in a genetic background that contains a DUX4 polyadenylation signal. Mutations in the structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1) gene, encoding a chromatin modifier of D4Z4, also result in the increased likelihood of DUX4 expression in individuals with a rare form of FSHD (FSHD2). Because SMCHD1 directly binds to D4Z4 and suppresses somatic expression of DUX4, we hypothesized that SMCHD1 may act as a genetic modifier in FSHD1. We describe three unrelated individuals with FSHD1 presenting an unusual high clinical severity based on their upper-sized FSHD1 repeat array of nine units. Each of these individuals also carries a mutation in the SMCHD1 gene. Familial carriers of the FSHD1 allele without the SMCHD1 mutation were only mildly affected, suggesting a modifier effect of the SMCHD1 mutation. Knocking down SMCHD1 in FSHD1 myotubes increased DUX4 expression, lending molecular support to a modifier role for SMCHD1 in FSHD1. We conclude that FSHD1 and FSHD2 share a common pathophysiological pathway in which the FSHD2 gene can act as modifier for disease severity in families affected by FSHD1.