基于数据非依赖型采集质谱技术的血液脂质分子高通量分析

脂质是生物体的重要代谢分子,参与重要的细胞生物功能,已有报道表明环境中污染物会干扰生物体正常循环及代谢机制,导致脂肪代谢紊乱。基于数据非依赖型(DIA)采集质谱技术,通过优化UPLC-QTOF MS(超高效液相色谱飞行时间质谱联用)液相分离方法,开发了少量人体血液样品中脂质代谢分子的高通量分析方法,并将其应用于57个普通人群的血液样品分析,在10μL人体血液样品中检出2 598个信号,经脂代组学质谱库匹配解析鉴定出八大类1 780个脂质分子,其中分子数目占比最大的脂质为甘油磷脂类(37%),其次依次为脂肪酸类(23%)、固醇脂类(13%)、甘油脂类(10%)、鞘脂类(9.0%)、孕烯醇酮脂类(4.8%)。上述研究建立的脂质分子高通量分析方法为以脂质代谢为毒性终点的污染物毒性筛查和毒理机制研究提供方法学基础。     

纳米四氧化三铁吸附水中六价铬后的复合物对HEK293细胞的毒性研究

磁性纳米粒子是一种环境友好型吸附剂,广泛应用于废水中重金属的处理。目前,有不少关于纳米粒子毒性的研究,但对处理后的纳米粒子和金属的复合物的毒性却鲜有研究。本文利用纳米四氧化三铁(MNPs)吸附水中的铬离子,以人胚胎肾细胞HEK293为生物模型,通过测定细胞活力、活性氧含量以及细胞摄取量等试验,评估磁性纳米四氧化三铁吸附六价铬后的复合产物对HEK293细胞的毒性。实验结果显示:在本实验浓度和作用时间下,Cr(Ⅵ)离子能够进入细胞,产生氧化应激,并引起细胞毒性;与Cr(Ⅵ)离子相比,磁性纳米四氧化三铁吸附Cr(Ⅵ)后的修复产物MNPs/Cr(Ⅵ)对HEK293细胞无明显毒性效应,MNPs/Cr(Ⅵ)复合物在细胞内的摄取极少,只有极少数颗粒通过内吞的方式进入细胞,且没有进入细胞核内。因此,在本实验的作用浓度和时间下,利用MNPs吸附水环境中Cr(Ⅵ)后的复合物对HEK293细胞没有明显毒性,本研究为深化了解MNPs及其重金属复合物对环境的影响提供了实验依据和参考价值。     

重金属暴露与前列腺癌发生和进展的关系综述

前列腺癌是男性泌尿系统发病率最高的恶性肿瘤.目前关于其发病机制有很多不同的学说,其中环境中的重金属暴露引起前列腺癌的研究逐渐成为研究热点之一.文章重点阐述了镉、砷、铜等重金属导致前列腺癌发生和发展的最新研究进展.研究发现,重金属暴露能够导致前列腺上皮细胞抗凋亡能力增强、雌激素受体增加、DNA甲基化异常、肿瘤干细胞形成,最终导致正常的前列腺上皮细胞发生恶性转化.关于重金属暴露引发前列腺癌的更多机制还有待进一步深入研究.因此,研究环境中重金属暴露导致前列腺癌发生机制对职业性暴露的人群提供健康指导以及预防前列腺癌的发生均具有重要的现实意义.     

ROS介导的氧化应激在INH诱导的细胞毒性中的作用及槲皮素的干预

为探讨ROS介导的氧化应激在异烟肼(INH)诱导L-02细胞毒性中的作用及槲皮素的干预作用,建立体外培养INH诱导L-02细胞氧化损伤模型,实验分为对照组(A)、INH组(B)、槲皮素低剂量组(C)及槲皮素高剂量组(D)。采用生化分析法检测L-02细胞培养液中天冬氨酸氨基转移酶(AST)和丙氨酸氨基转移酶(ALT)的活性;利用荧光探针检测L-02细胞线粒体内活性氧(ROS)水平;应用比色法检测L-02细胞内丙二醛(MDA)、谷胱甘肽(GSH)的含量以及主要抗氧化物酶的活性。结果表明,与对照组相比,INH能显著增加L-02细胞培养液中AST和ALT的活性、细胞线粒体内ROS水平及细胞内MDA的含量(P0.01),并显著减少L-02细胞内GSH的含量及超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)的活性(P0.01)。与INH组比较,槲皮素低剂量组L-02细胞培养液中AST的活性、线粒体内ROS水平及细胞内MDA的含量明显降低(P0.05),而细胞内SOD的活性明显增加(P0.05);高剂量槲皮素能显著降低L-02细胞培养液中AST和ALT的活性、细胞线粒体内ROS水平及细胞内MDA的含量(P0.01),并能显著增高L-02细胞内GSH的含量和主要抗氧化物酶的活性(P0.01)。与槲皮素低剂量组相比,槲皮素高剂量组的保护效应更明显(P0.05)。可见,ROS介导的氧化应激在INH诱导的L-02细胞毒性中发挥了重要作用,且槲皮素对INH诱导的L-02细胞氧化损伤具有保护作用。     

短链氯化石蜡暴露对HepG2细胞代谢的影响

短链氯化石蜡(short-chain chlorinated paraffins,SCCPs)是一组成分复杂的氯代正构烷烃,在环境中普遍存在。然而有关其毒性机理的信息十分有限,限制了对其健康风险的评估。本研究采用液相色谱–串联质谱(LC-MS/MS)分析技术,研究了不同剂量的SCCPs暴露(0、1.0、10.0和100.0μg·L-1;C13-CPs;55.0%Cl)对人体肝癌细胞Hep G2的糖代谢、氨基酸代谢和脂肪酸代谢的影响。通过偏最小二乘判别分析(PLS-DA)鉴别各组代谢产物谱差异,发现3个SCCPs暴露剂量组均能够与对照组完全分开,表明SCCPs短期暴露能够引起细胞代谢活动的显著改变。SCCPs的低剂量暴露可明显刺激Hep G2细胞对氨基酸的吸收。与对照组相比,SCCPs低剂量暴露组(1.0μg·L-1)培养基中谷氨酰胺、色氨酸和丝氨酸的含量显著(P0.05)降低。而高剂量SCCPs(100.0μg·L-1)暴露抑制了细胞对氨基酸和葡萄糖吸收,但促进了乳酸、丙氨酸、半胱氨酸的生成。氨基酸吸收的抑制不可避免地会影响蛋白质的合成。同时,SCCPs的暴露使饱和脂肪酸代谢紊乱,使不饱和脂肪酸水平上调。为确定SCCPs的毒性作用方式,有必要从转录组和蛋白组层面进一步研究其毒性机制。     

基于HepG2细胞脂质组学方法对黄浦江水质的综合评价

环境水体中复合污染的毒性识别一直是环境科学界关注的热点.基于代谢组学的生物监测方法通过监测暴露前后生物内源性代谢物的变化,在评估复合污染导致的综合毒性效应中具有广泛的应用前景.本研究从污染物对细胞脂类代谢的影响角度出发,采用体外肝癌细胞(HepG2)暴露和脂质组分析相结合的方法,对黄浦江干流和支流共27个采样点的水质进行了综合评价.研究发现,水样对HepG2细胞的脂代谢影响程度与采样点所属河段紧密相关.黄浦江中游水样对HepG2细胞的平均脂代谢影响程度(3.40％)高于上游(1.65％)和下游(0.78％),而流经城区的支流水样对细胞的脂代谢影响(5.20％)明显高于干流水样(1.80％).此外,在采集的水样中超过70％的样品都导致HepG2细胞内甘油三酯(TG)大量蓄积,揭示了黄浦江水体中的复合污染物可能诱导肝脏产生脂毒性损伤.本研究为环境水质监测提供新的方法,研究结果为上海市生态环境和水质安全管理部门提供重要的参考信息.     

四溴双酚A对人体正常肝细胞毒性效应及作用机制

四溴双酚A(TBBPA)作为目前用量最大的一种溴系阻燃剂,在含TBBPA用品的生产、使用和废弃处置过程中,能够通过多种途径进入环境介质,造成持久性污染,危害生态系统和人体健康.为探明TBBPA对人体健康的潜在毒性效应及作用机制,选取人体正常肝细胞L02作为模型,通过分析暴露后细胞形态、存活率、胞内活性氧(ROS)含量、DNA损伤及细胞凋亡等变化.结果表明,TBBPA暴露导致L02细胞形态发生明显改变、存活率显著降低,细胞彗星实验拖尾现象明显增强;随着暴露浓度的升高,L02细胞胞内ROS含量、丙二醛(MDA)含量和氧化型谷胱甘肽/还原型谷胱甘肽(GSSG/GSH)比值均呈现剂量依赖性增加.40μmol·L-1暴露条件下胞内ROS含量升高3.1倍;20 μmol·L-1和40 μmol·L-1暴露条件下,细胞凋亡率分别增加了32倍和4.8倍.推测TBBPA暴露对L02细胞的毒性效应作用机制为,暴露引起细胞氧化应激水平升高,ROS升高再引起DNA损伤程度增强,最终导致细胞凋亡率增加.上述研究结果将为评估TBBPA的毒性效应和健康风险提供科学依据.     

六价铬诱导的肝细胞线粒体依赖性凋亡中VDAC1的作用

铬(chromium)是一种在工业生产过程中广泛使用的重金属,进入人体后可导致急慢性中毒,具有神经毒性、基因毒性、致癌性和免疫毒性。了解六价铬(hexavalent chromium,Cr(Ⅵ))的细胞毒性,进一步探究Cr(Ⅵ)的毒作用机制,可为防治Cr(Ⅵ)对人群健康的损害提供实验依据。电压依赖性阴离子通道蛋白1(voltage-dependent anion channel-1,VDAC1)参与调控线粒体外膜通透性,影响细胞凋亡;同时VDAC1也是BCL-2家族的重要结合位点,它可与BAX/BAK相互作用形成孔道,使线粒体内的凋亡相关蛋白,如细胞色素C等,进入胞浆,引起细胞凋亡。但VDAC1影响细胞凋亡的确切路径与分子机制,目前尚未完全研究清楚。使用L02人正常肝细胞作为实验对象,通过慢病毒包装法建立VDAC1低表达细胞系,检测在相同浓度Cr(Ⅵ)处理的条件下,与非染毒组相比,不同受试细胞的生存率、凋亡情况、活性氧簇(reactive oxygen species,ROS)生成量、线粒体功能和凋亡诱导因子(AIF)的变化情况是否存在差异。结果表明,与VDAC1正常表达的细胞相比,VDAC1低表达组在Cr(Ⅵ)染毒的情况下,细胞生存率升高,凋亡率下降,细胞内ROS生成量减少,MPTP活性增加不明显,胞浆内细胞色素C(Cytochrome C,Cyt C)和AIF含量降低。上述研究结果表明VDAC1参与了由六价铬诱导的线粒体依赖性肝细胞凋亡,并且抑制VDAC1的表达可减轻因Cr(Ⅵ)暴露而引起的L02肝细胞损伤。     

血清对Hela细胞内硫醇浓度和甲醛诱导性DNA-蛋白质交联（DPC）的影响

吸入性甲醛如何将其遗传毒性从呼吸器官经血液转移全身?这是揭示"甲醛致白血病"这个科学问题的关键.以新生牛血清(NBS)为"模拟血液",以Hela细胞为实验材料,采用体外甲醛染毒实验,研究了培养基血清对细胞内硫醇浓度,以及对甲醛诱导性DNA-蛋白质交联(DPC)的影响.结果表明,当培养基中未添加血清时,250μmol·L-1甲醛仅引起较低水平的交联效应,同时细胞内硫醇浓度水平也较低;而加入1%和10%新生牛血清以后,甲醛诱导的DPC均显著上升(p<0.01,p<0.05),同时细胞内硫醇浓度水平也显著上升(p<0.05,p<0.01).培养基中新生牛血清能够再生Hela细胞内的硫醇,同时促进细胞DPC的形成.这可能为理解甲醛远距离毒性,解释吸入甲醛是否能导致白血病提供了基础.     

重金属人体生物有效性、吸收及毒性研究中的肠道细胞模型

重金属污染对人体健康产生极大威胁,因而备受关注.肠道吸收是人体重金属暴露的主要途径之一,因此,重金属的生物有效性、肠道吸收过程和毒性研究成为当前的研究热点.体外胃肠模拟法和动物模型被广泛用于重金属的相关研究,然而体外胃肠模拟法缺少人体肠道细胞成分,动物模型与人体存在着物种差异且实验成本高.鉴于此,研究者开发了能够部分模拟人体肠道上皮功能的体外肠道细胞模型.此模型作为研究生物有效性的重要工具,能模拟肠道对重金属的吸收转运过程,并能够结合分子生物学等技术、采用多学科交叉的研究方法探索重金属的肠吸收和肠毒性的分子机制.本文系统介绍了人肠上皮的结构功能、肠道上皮细胞对重金属吸收转运机制、肠道细胞模型的发展及其在重金属相关研究中的应用与优缺点,总结了肠细胞模型功能验证指标和优化方法.同时,还对肠道微流控培养系统(芯片肠道)和肠类器官等三维肠细胞模型技术的最新进展进行了介绍和展望.     

A comparative study of the toxicity of lead and its impact on the carbohydrate metabolism and some haematological parameters of cichlid fish,oreochromis niloticus and catfish,clarius gariepinus from saudi arabia

Fresh and healthy specimens of Oreochromis niloticus (mean weight 70.5± 1.23 g and mean length, 12.3± 1.5cm) and Clarias gariepinus (mean weight, 41.8±2.3 g and mean length 13.78 ± 1.2 cm) were exposed to heavy metal lead, ranging in concentration from 10 to 18 mg L^‐1 for O. niloticus and 20 to 28 mg L^‐1 for C. gariepinus respectively. The 96 h LC₅₀ for both the species was computed as 12.45 mg L^‐1 (O. niloticus) and 22.65 mg L^‐1 (C. gariepinus). The cichlid fish was exposed to sublethal concentration of lead (2, 4 and 6 mgL^‐1) and catfish (4, 8 and 12 mgL^‐1). The erythrocytes count, haemoglobin concentration, haematocrit and the value of serum glucose increased significantly (P < 0.01), whereas leucocytes count, serum protein and serum triglyceride after intoxication declined in both the species with the same pattern but in different quantity. After 96 h of time a significant depletion of muscle and liver glycogen was noted, being greater in muscle (16.7% in O. niloticus) and in liver (15.9% in C. gariepinus). The response of fish to lead was dose dependent.     

Characterizing the resident, fermentative microbial consortium in the hindgut of the temperate-zone herbivorous fish, Hermosilla azurea (Teleostei: Kyphosidae)

The zebraperch, Hermosilla azurea Jenkins and Evermann, a warm-temperate marine fish species with a strictly macroalgal diet, has a relatively long digestive tract with an enlarged hindgut and an associated blind caecum (HC). In zebraperch sampled off Santa Catalina Island, California (33°19′42′′N; 118°18′37′′W) in years 1995 through 2001, direct cell counts, gut epithelium assessment of bacterial attachment, and short-chain fatty acid (SCFA) analyses verified that the zebraperch HC possesses a dense and morphologically diverse, fermentative microbiota. Bacterial cell counts and morphological diversity were significantly higher in HC contents compared to anterior gut regions, suggesting that microbial populations were growing along the digestive tract. Similarly, electron micrographs of the HC epithelium revealed attached microbes, further supporting the possibility that these organisms constitute resident microbiota. Five different SCFAs were detected in all three regions of the digestive tract, but levels were up to three times greater in HC contents. Acetate was consistently the prevailing SCFA in all gut regions. Sequence analysis of bacterial 16S rDNA was used to identify predominant bacterial groups in HC contents. Of the seven main bacterial types identified, Enterovibrio spp. were the dominant bacteria in HC contents followed by species of Bacteroides,Faecalibacterium, and Desulfovibrio. Taken together, our findings show that the zebraperch HC harbors a consortium of microbes that appears to assist in the breakdown of algal polysaccharides in the herbivorous diet of the fish.     

Serum Iron Concentrations, Lipid Peroxidation and Superoxide Dismutase Activity in Turkish Iron Miners

The effects of iron exposure, on serum iron, serum superoxide dismutase (SOD), a free radical scavenger, and plasma malondialdehyde (MDA), a lipid peroxidation parameter, were investigated in Turkish iron miners, office workers and healthy control subjects. Serum iron levels in both miner and office workers groups were higher than those of healthy controls (p < 0.05). There were higher mean values of plasma MDA levels in both iron miners and office workers compared to controls (p < 0.05). Serum SOD activity in the miner group was lower than that of controls (p < 0.05). These results suggested that elevated MDA levels in both miners and office workers were the result of an increased production and/or decreased catabolism of MDA in chronic iron exposure. These changes in MDA metabolism may be due to iron-induced lipid peroxidation in the blood and related body compartments.     

铜污染草地对放牧乌蒙半细毛羊矿物质元素代谢的影响

为了评价草地铜污染对放牧乌蒙半细毛羊的影响,探讨铜污染的治理方法,在乌蒙山区的妈姑镇和凉水沟开展草地放牧试验和矿物质元素补充研究。应用原子发射光谱分析土壤、牧草和动物组织的重金属含量,应用全自动血液分析仪分析血液指标。放牧试验的结果显示:铜污染草地放牧明显增加了动物组织铜和锌的含量(P 0.01),降低了动物组织钼和铁的含量(P 0.01),试验结束时,试验组动物的血红蛋白(Hb)、红细胞压积(PCV)、红细胞数(RBC)和平均红细胞体积(MCV)显著低于对照组(P 0.01),羊毛产量和长度显著低于对照组(P 0.01)。矿物质元素补充试验的结果显示:补充硫酸钠明显降低了铜污染草地放牧动物血液和肝脏铜元素含量,补充试验结束时,处理Ⅰ组动物血液的Hb、PCV、RBC和MCV显著高于处理Ⅱ组(P 0.01),血液指标达到正常范围。处理Ⅱ组动物血液和肝脏铜元素的含量继续升高,动物组织钼的含量继续降低(P 0.01),Hb、PCV和RBC继续下降,试验结束时出现溶血性贫血,但补充硫对羊毛品质的相关指标没有显著的影响。研究表明,铜污染草地严重影响了乌蒙半细毛羊的矿物质代谢,补充硫酸钠可以部分拮抗铜的毒性。     

Lethal effects of Northwest Atlantic Ocean isolates of the dinoflagellate, Scrippsiella trochoidea, on Eastern oyster (Crassostrea virginica) and Northern quahog (Mercenaria mercenaria) larvae

The thecate dinoflagellate Scrippsiella trochoidea is a cosmopolitan, bloom-forming alga that has been generally considered non-toxic. Here, we report that environmentally relevant cell densities (10⁴ cells mL⁻¹) of Scrippsiella trochoidea strains isolated from the Northwest Atlantic Ocean caused 100% mortality in Eastern oyster (Crassostrea virginica) larvae during 3-day exposures while parallel control larvae exhibited 100% survival. S. trochoidea also exhibited lethal effects on Northern quahog (Mercenaria mercenaria) larvae (70% mortality during 3-day exposure) but were non-toxic to juvenile fish (Cyprinodon variegates). The cultures of S. trochoidea were more lethal to Northern quahog larvae than ten other species of harmful algae, including the highly toxic species Cochlodinium polykrikoides. Scrippsiella trochoidea cultures within later stages of growth were more toxic than exponential growth stages to bivalve larvae, and the toxicity was dose dependent. Furthermore, toxicity was maintained in the cultures that were sonicated, boiled, and frozen as well as in resuspended residues of the culture but was significantly lower in cell-free culture media. Collectively, these results suggest that S. trochoidea causes mortality in bivalve larvae through a physicochemical rather than strictly chemical mechanism, such as clogging of larval feeding apparatuses by materials produced by S. trochoidea (e.g., lipids, extracellular polysaccharides, and/or cell debris) which accumulate as cells in culture or blooms age. This is the first report of the lethal effects of Scrippsiella trochoidea on shellfish larvae.     

Alterations inras-gene expression and intracellular distribution of protein kinase C in the spongeGeodia cydonium in response to marine pollution

The siliceous spongeGeodia cydonium Jameson was used to study the influence of pollution in marine environments on selected parameters of the intracellular signal transduction pathway. The parameters chosen were: intracellular distribution of protein kinase C (PK-C),ras-gene expression and DNA polymerasealpha (DNA Polalpha) activity. Both PK-C andras-gene product (ras-protein) have previously been established to be key molecules in the intracellular signalling pathway in sponges; increased level ofras-protein mediates events following sponge cell-cell contact. Three unpolluted and three polluted sites in the off-shore seawater around Rovinj (Yugoslavia) were selected for the study in 1989. The state of pollution of these sites has been well-defined in a series of previous studies (1976 to 1989). Transplantation of regenerating sponge cubes ofG. cydonium to the polluted sites resulted in pronounced changes in the parameters chosen, compared to controls exposed to unpolluted environments. Expression ofras gene was increased by three- to five-fold after exposure of regenerating sponge tissue to the impacted sites. At the site with the highest pollutional load,ras mRNA level was about 50% of that at the reference sites. In parallel experiments it was established that, in response to pollution, a translocation of PK-C from the cytosolic to membrane fraction occurred. At the most impacted site, most of the enzyme activity was cytosolic. DNA Polalpha-activity, as a measure of sponge cell proliferation, decreased in a pollutioncorrelated manner. Our results indicate that the intracellular signalling system within sponge cells is activated in response to moderate pollution but is depressed in heavily polluted environments.     

Isolated bacteriocyte cell suspensions from the hydrothermal-vent tubeworm Riftia pachyptila,a potent tool for cellular physiology in a chemoautotrophic symbiosis

The hydrothermal-vent tubeworm Riftia pachyptila relies entirely on its intracellular chemoautotrophic symbionts to sustain its metabolism. The host must therefore provide them with inorganic metabolites, including carbon. This study describes a tool for studying cell processes occurring in a bacteria-containing cell by the dissociation of trophosome cell types. The physiological assays performed on cell preparations focused on carbon dioxide conversion and transport processes. Trophosome tissue was mechanically dissociated, resulting in cell suspensions enriched in small (7-20 µm) bacteriocytes, which were viable for several hours. In addition, medium-term cell cultures were also attempted. As a start to the understanding of the CO₂ metabolism of these cells, we were interested in evidence of carbonic anhydrase (CA) isoforms, ATPases and chloride exchangers. Variations in intracellular and extracellular pH, and in intracellular concentrations of sodium, potassium and chloride, were followed after addition of selective inhibitors. The data presented here suggest the occurrence of potential cytosolic and membrane-associated carbonic anhydrase isoforms in the bacteriocytes, proton-driven sodium-ATPases and a well represented anion transporter exchanging intracellular chloride against extracellular anions.     

Intraspecific variation in the red alga Portieria hornemannii : monoterpene concentrations are not influenced by nitrogen or phosphorus enrichment

The red alga Portieria hornemannii (Lyngbye) Silva was selected to test the effects of enhanced nutrient availability on the production of carbon-based secondary metabolites, because of its notable site-to-site variation in monoterpene production. On Guam, the major secondary metabolite produced by this alga is ochtodene, a cyclic monoterpene. Quantitative high-performance liquid-chromatography analysis of the extracts of P. hornemannii collected from six sites on Guam showed that both ochtodene and triglyceride concentrations differed significantly among sites. Internal nitrogen and phosphorus content of the algae did not correlate with the observed variation in chemistry. Experimental enhancement of N-alone, P-alone or N + P in the field for 5 wk failed to induce a significant change in ochtodene concentrations in the alga, while triglyceride concentrations increased significantly in the N + P treatment. Ochtodene and triglyceride concentrations did not change among similar treatments in shaded (18 d) and unshaded (11 d) fertilization experiments conducted in the laboratory. Variation in ochtodene concentrations in P. hornemannii cannot be attributed to N and P availability; however, the decrease in ochtodene and triglyceride concentrations during the shaded laboratory experiment suggests that light may be a factor influencing monoterpene biosynthesis. The difference in ochtodene concentration between the initial and final sets of field controls collected for the unshaded laboratory experiment suggests that temporal variation might also contribute to differences observed among the algae at the different sites. Received 11 June 1996 / Accepted 20 July 1996     

Effects of host-tissue homogenate of the scleractinian coral Plesiastrea versipora on glycerol metabolism in isolated symbiotic dinoflagellates

Symbiotic dinoflagellate algae (Symbiodinium sp.) isolated from the scleractinian coral Plesiastrea versipora and incubated in homogenized host tissue released 4 to 7 times as much glycerol (14 to 46 nmol glycerol/10⁶ algae) as those incubated in seawater (3 to 6 nmol glycerol/10⁶ algae) after 4 h incubation in the light. During this period, no release of triglycerides was detected. Intracellular glycerol increased 2- to 3-fold in algae incubated in host homogenate, but remained unchanged in algae incubated in seawater at a concentration of 0.82 ± 0.47 nmol glycerol/10⁶ algae. In each incubation condition, intracellular triglyceride levels increased. However, in algae incubated in host homogenate, the intracellular levels of triglycerides reached only about 75% of the amount reached in algae incubated in seawater (max. 18.55 ± 2.40 nmol glycerol/10⁶ cells). Host homogenate did not stimulate the release of glycerol from algae during dark incubation. These data show that the glycerol released by algae incubated in host-tissue homogenate was derived from increased synthesis of glycerol or from diversion of some glycerol or other photosynthetic intermediates from incorporation into algal triglyceride stores, and did not come from existing stores. Received: 20 December 1996 / Accepted: 9 January 1997     

Chromium speciation in the blood of metal-on-metal hip implant patients

The objective of this study was to determine the valence state of chromium (Cr) in the blood of individuals with Cr-containing metal hip implants. Serum and red blood cell (RBC) Cr concentrations from 52 patients with Cr-containing total hip arthroplasties were measured preoperatively and at 3, 12, and 24 months postoperatively. Geometric mean and median pre-surgery serum Cr concentrations were consistently below 0.2 µg/L, while geometric mean and median pre-op RBC Cr concentrations were typically about four- to six-fold higher than the serum values. A significant 5- to 13-fold increase was found in the mean and median serum Cr concentrations three months post-surgery, with an 8- to 18-fold rise at 12 and 24 months, respectively. Steady-state serum concentrations were reached between 3 and 12 months. In contrast, there were no marked differences in mean and median RBC Cr concentrations pre- and post-surgery. Slope regression analysis for our data was similar to those reported for Cr(III) in spiked blood samples. The analysis showed that Cr released from hip implants preferentially distributed into serum and not RBC, indicating that the form of Cr present in blood of hip implant patients was in the form of non-toxic Cr(III). Our findings indicate that blood Cr concentrations Cr(III) associated with metal implants do not pose an adverse health risk to patients, which is in agreement with findings published by most investigators.