The developmental toxicity of perfluoroalkyl acids and their derivatives

Perfluoroalkyl acids such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have applications in numerous industrial and consumer products. Although the toxicology of some of these compounds has been investigated in the past, the widespread prevalence of PFOS and PFOA in humans, as demonstrated in recent bio-monitoring studies, has drawn considerable interest from the public and regulatory agencies as well as renewed efforts to better understand the hazards that may be inherent in these compounds. This review provides a brief overview of the perfluoroalkyl chemicals and a summary of the available information on the developmental toxicity of the eight-carbon compounds, PFOS and PFOA. Although the teratological potentials of some of these chemicals had been studied in the past and the findings were generally unremarkable, results from recent postnatal studies on developmental and reproductive indices have prompted consideration of their relevance to human health risk. Based on current understanding of the developmental effects of PFOS and PFOA in rodents, several avenues of research are suggested that would further support the risk assessment of these perfluorinated organic chemicals.     

Secretion of human chorionic gonadotropin in superfused young placental tissue exposed to cadmium

The effect of various concentrations of cadmium (Cd) in levels ranging from 0.75 to 12 μg/ml medium, on the secretion of human chorionic gonadotropin (hCG) in first-trimester placental expiants, after 6 or 24 h incubation, employing both static and dynamic systems was examined. Later the unbound Cd was washed for 45 min with fresh medium devoid of Cd, followed by superfusion with the latter medium for 75 min, during which time samples were collected for hCG assay. For the superfusion experiments the parameters used for evaluating the hCG secretion pattern were: mean peak amplitude (MPA), pulse frequency (PF) and the area under the hCG secretion curve (AUC). The results indicate that in the dynamic system the hCG secretion increased significantly, and this increase was dose dependent. There was also a dose-related increase in mean total hCG secreted by the explants exposed to Cd. Maximal hCG secretion was observed after 24 h exposure of explants to 6 μg of the metal/ml. Both the MPA and AUC parameters showed a statistically significant increase for this dose level. At 12 μg/ml, the pulsatile secretion of hCG decreased, the value for the mean hCG secretion being comparable to that observed for 0.75 μg/ml. After 6 h incubation, however, there were no significant changes from the control, as judged by all of the above parameters. The levels of hCG secreted by the explants into the media in the static system were not significantly different from their respective controls, for both incubation periods and Cd levels. These results indicate that Cd may affect the normal placental function, as reflected in its hCG secretion pattern.     

Combining perfluoroalkane acid exposure levels for risk assessment

Perfluoroalkane acids are present in biologic samples from >90% of people in the developed world. Because people may be exposed to multiple perfluoroalkane acids, it is reasonable to consider whether the exposure levels of these agents can be combined for risk assessment purposes. To investigate this possibility, we considered whether the literature on perfluoroalkane acids could be used to justify a scaling system analogous to the Toxic Equivalency Factor (TEF) system used for polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans. We evaluated pairs of studies performed with different perfluoroalkane acids in the same species using the same design and found that endpoints for perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorobutanesulfonate (PFBS), and perfluorodecanoic acid (PFDA) could be discordant. We evaluated pairs of rat studies of PFOS, PFOA, and PFBS performed with the same design for which dose-response curves could be modeled for the concordant endpoints, but we were unable to identify a scaling system that gave values consistently within an order of magnitude for the same compounds. Currently available data do not support the combining of exposure levels of perfluoroalkane acids for risk assessment, although re-evaluation after additional data are available is recommended.     

Effects of low concentrations of organochlorine compounds in women on calcium transfer in human placental syncytiotrophoblast.

For most Canadians, food represents one of the major sources of environmental contaminants. Among them, organochlorine compounds (OCs) are known to affect calcium (Ca2+) homeostasis. They are neurotoxic by perturbation of Ca2+ channels and pumps, and they interfere with protein kinase C (PKC) and Ca2+ binding protein (CaBP). Ca2+ is an essential element to adequate fetal growth and development. The aim of the present study is to determine the relation between low environmental maternal exposure to OCs, such as polychlorinated biphenyls (PCB 153), Aroclor 1260, p,p'-dichlorodiphenyltrichloroethane (DDT) and p,p'-dichlorodiphenyl-dichloroethane (DDE), Ca2+ levels in serum and placenta, placental Ca2+ transfer, and newborn development. Total Ca2+ and OCs were measured in women's serum samples, as well as in umbilical cord's serum and placenta at term. Placentas were taken for trophoblast cells isolation and Ca2+ incorporation kinetic experiments. Our results were obtained from 30 pregnant women from the southwestern area of Quebec. Concentrations of Aroclor 1260, PCB 153, DDE, and DDT were respectively 6.1, 6.0, 3.1, and 2.9 times lower in the umbilical cord serum than in the mother's serum at term. In the placenta, DDE was accumulated at higher levels than other contaminants. A tendency towards an inverse relation was observed for in OCs found in three compartments and Ca2+ levels in maternal serum and in placental tissues. Maternal Ca2+ concentrations do not influence Ca2+ uptake by syncytiotrophoblast. Only DDE (>/=0.70 mug/l) in maternal serum significantly was associated with a small increase in Ca2+ uptake by syncytiotrophoblast. This study will help us determine if low OC contamination significantly modifies Ca2+ transfer in syncytiotrophoblast.     

Endocrine and cardiovascular responses to a series of graded physical and psychological stress stimuli in healthy volunteers

To investigate the endocrine and cardiovascular responses to a series of psychological and physical stress stimuli and to investigate the possibility of a stimulus intensity-response relation of endocrine and cardiovascular reactivity, 18 healthy volunteers were exposed to psychological and physical stimuli of increasing intensity. Each volunteer participated in three experimental sessions on separate days. The sequence of the sessions was such that all volunteers first participated in a session in which they were not exposed to a stress stimulus, i.e. the control session. Then they were randomly assigned to enter two trial sessions in which they were consecutively exposed to a series of psychological stressors and a series of physical stressors. During each session blood pressure (BP) and heart rate (HR) were assessed and blood samples were taken, to determine cortisol and noradrenaline levels.

During the physical stress session increments in systolic and diastolic blood pressure and noradrenaline were observed, proportional to the intensity of the stimuli. In contrast, during the psychological stress session pronounced increments in heart rate were observed, with maximum responses at the second and third stimuli. Diastolic blood pressure responses showed a similar pattern, whereas no changes in noradrenaline were observed. Plasma cortisol was not increased by the psychological stressor, whereas it was stimulated by the physical stressor but at the highest stimulus intensity only. Although the size of the study population precludes any firm conclusions, the results suggest that a stimulus intensity approach in human stress research is possible. Furthermore, the results also appear to indicate that the cardiovascular and pituitary-adrenal systems may display stress-specific responses.     

Combined effects of perfluorooctane sulfonate (PFOS) and maternal restraint stress on hypothalamus adrenal axis (HPA) function in the offspring of mice

Although it is known that prenatal exposure to perfluorooctane sulfonate (PFOS) can cause developmental adverse effects in mammals, the disruptive effects of this compound on hormonal systems are still controversial. Information concerning the effects of PFOS on hypothalamus adrenal (HPA) axis response to stress and corticosterone levels is not currently available. On the other hand, it is well established that stress can enhance the developmental toxicity of some chemicals. In the present study, we assessed the combined effects of maternal restraint stress and PFOS on HPA axis function in the offspring of mice. Twenty plug-positive female mice were divided in two groups. Animals were given by gavage 0 and 6 mg PFOS/kg/day on gestation days 12-18. One half of the animals in each group were also subjected to restraint stress (30 min/session, 3 sessions/day) during the same period. Five plug-positive females were also included as non-manipulated controls. At 3 months of age, activity in an open-field and the stress response were evaluated in male and female mice by exposing them to 30 min of restraint stress. Male and female offspring were subsequently sacrificed and blood samples were collected to measure changes in corticosterone levels at four different moments related to stress exposure conditions: before stress exposure, immediately after 30 min of stress exposure, and recuperation levels at 60 and 90 min after stress exposure. Results indicate corticosterone levels were lower in mice prenatally exposed to restraint. In general terms, PFOS exposure decreased corticosterone levels, although this effect was only significant in females. The recuperation pattern of corticosterone was mainly affected by prenatal stress. Interactive effects between PFOS and maternal stress were sex dependent. The current results suggest that prenatal PFOS exposure induced long-lasting effects in mice.     

Perfluorinated chemicals: Differential toxicity,inhibition of aromatase activity and alteration of cellular lipids in human placental cells

The cytotoxicity of eight perfluorinated chemicals (PFCs), namely, perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorododecanoic acid (PFDoA), perfluorobutanesulfonate (PFBS), perfluorohexanesulfonate (PFHxS) and perfluorooctanesulfonate (PFOS) was assessed in the human placental choriocarcinoma cell line JEG-3. Only the long chain PFCs – PFOS, PFDoA, PFNA, PFOA – showed significant cytotoxicity in JEG-3 cells with EC50 values in the range of 107 to 647 μM. The observed cytotoxicity was to some extent related to a higher uptake of the longer chain PFCs by cells (PFDoA > PFOS ? PFNA > PFOA > PFHxA). Moreover, this work evidences a high potential of PFOS, PFOA and PFBS to act as aromatase inhibitors in placental cells with IC50s in the range of 57–80 μM, the inhibitory effect of PFBS being particularly important despite the rather low uptake of the compound by cells. Finally, exposure of JEG-3 cells to a mixture of the eight PFCs (0.6 μM each) led to a relative increase (up to 3.4-fold) of several lipid classes, including phosphatidylcholines (PCs), plasmalogen PC and lyso plasmalogen PC, which suggests an interference of PFCs with membrane lipids. Overall, this work highlights the ability of the PFC mixture to alter cellular lipid pattern at concentrations well below those that generate toxicity, and the potential of the short chain PFBS, often considered a safe substitute of PFOS, to significantly inhibit aromatase activity in placental cells.     

内皮细胞功能及其异质性研究的进展

血管内皮细胞具有广泛的生理功能，本文从血管形成、凝血及血小板和内皮细胞的相互作用、炎症和免疫反应、合成基质成分、调节血管张力和脂质代谢等方面，综述了内皮细胞的功能。重点介绍了各类组织和动物内皮细胞之间的区别，主要体现在形态、功能、表面抗原及对内皮损伤后的反应等方面。     

Shiga Toxins: Intracellular Trafficking to the ER Leading to Activation of Host Cell Stress Responses

Despite efforts to improve hygenic conditions and regulate food and drinking water safety, the enteric pathogens, Shiga toxin-producing Escherichia coli (STEC) and Shigella dysenteriae serotype 1 remain major public health concerns due to widespread outbreaks and the severity of extra-intestinal diseases they cause, including acute renal failure and central nervous system complications. Shiga toxins are the key virulence factors expressed by these pathogens mediating extra-intestinal disease. Delivery of the toxins to the endoplasmic reticulum (ER) results in host cell protein synthesis inhibition, activation of the ribotoxic stress response, the ER stress response, and in some cases, the induction of apoptosis. Intrinsic and/or extrinsic apoptosis inducing pathways are involved in executing cell death following intoxication. In this review we provide an overview of the current understanding Shiga toxin intracellular trafficking, host cellular responses to the toxin and ER stress-induced apoptosis with an emphasis on recent findings.     

SYNTHESIS OF CARBOXYL TERMINAL SEGMENTS OF BETA-SUBUNIT OF HUMAN CHORIONIC GONADOTROPIN

The synthesis in solution of carboxyl terminal peptide segments of the beta-subunit of human chorionic gonadotropin is described. The protected segments include sequences 119–131, 132–137, and 138–145. The syntheses were based on a standardized liquid-liquid extraction program for routine purification of intermediates (two-phase method). Condensation of terminally deblocked segments afforded protected peptides 132–145, 126–145, 120–145 and 119–145. Protected peptides 126–145 and 120–145 were deprotected in liquid hydrogen fluoride and used in conjugated form for immunization of rabbits. Data on the specificity of the antibody response are reported.     

Development of angiogenesis inhibitors for cancer therapy

Abundant literature exists demonstrating that tumors are dependent on angiogenesis for both tumor growth and invasion. The extent of angiogenesis in primary tumors has been demonstrated to be associated with a negative prognosis in several tumors including non-small cell lung carcinoma, prostate cancer, and in node-negative breast cancer, where angiogenesis is an independent negative prognostic factor. These data demonstrate the significance of angiogenesis in tumor biology and indicate that it can be utilized as a target for novel therapeutic strategies. The recent expansion of knowledge into the specific pathways of tumor angiogenesis has provided reagents which can now be utilized to provide markers of efficacy of antiangiogenic agents in cancer patients. A critical part of the development of angiogenesis inhibitors for cancer therapy is the clinical trial strategy. Since these agents are primarily thought to be cytostatic, carefully designed trials must be conducted which focus on appropriate endpoints and integrate relevant biologic markers to support efficacy.     

基于斑马鱼模型不同提取方法人源胎盘冻干粉抗抑郁活性及作用机制研究

目的 明确人源胎盘冻干粉是否具有抗利血平诱发斑马鱼抑郁症的活性,比较不同提取方法胎盘冻干粉抗抑郁活性并探索其作用机制。方法 将6月龄野生型斑马鱼AB随机分为8组：对照组、模型组、丁螺环酮（阳性药,3mg·L^-1）组和胎盘冻干粉酶解、水提、50%醇提、醇提、二氯甲烷提（均为5mg·L^-1）组,每组12条。除对照组外,各组以利血平处理20min造模,而后更换相应含药养鱼用水,至14d,每天换水。14d时用Zebrabox斑马鱼行为分析仪对各组斑马鱼进行新型水槽测试,分析其行为变化。收集鱼脑,实时荧光定量PCR（qRT-PCR）法检测抑郁、神经调控相关基因（bdnf、pomc、hcrt、mao、nf-κb、pparγ）的mRNA表达;试剂盒法检测氧化应激相关超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性。结果 与对照组比较,模型组斑马鱼进入新型水槽上部次数显著减少（P＜0.001）,上部游动距离及时间比例均显著减少（P＜0.001）;与模型组比较,丁螺环酮、胎盘冻干粉酶解物组斑马鱼进入上部次数显著增加（P＜0.05）,上部游动距离及时间比例均显著增加（P＜0.05）。与对照组比较,模型组中的bdnf、pomc、hcrt和mao基因表达显著上调（P＜0.01、0.001）,nf-κb和pparγ基因表达显著下调（P＜0.05、0.01）;与模型组比较,经不同提取方法胎盘冻干粉处理后bdnf、pomc和mao基因表达显著下调（P＜0.05、0.01、0.001）,酶解、水提、醇提组hcrt mRNA水平显著降低（P＜0.05、0.001）,酶解、水提组nf-κb mRNA水平和酶解组pparγ mRNA水平显著上调（P＜0.01）。与对照组比较,模型组CAT活性显著升高（P＜0.001）,SOD活性升高,但没有统计学意义;与模型组比较,经不同提取方法胎盘冻干粉处理后CAT活性显著降低（P＜0.001）,SOD活性有不同程度的降低。结论 人源胎盘冻干粉具有抗利血平诱发斑马鱼抑郁症的活性,且胎盘冻干粉酶解抗抑郁症活性最好,作用机制可能与改善氧化应激状态有关。     

凶险性前置胎盘规范化管理临床研究

研究凶险性前置胎盘规范化管理的临床作用。将2014年1月至2016年6月在锦江区妇幼保健院妇产科住院进行规范化管理的124例凶险性前置胎盘患者作为研究组,以同期诊断为中央性前置胎盘非瘢痕子宫患者162例作为对照组,比较2组围术期孕产妇情况和围生儿结局。研究组在患者手术时间、输血、子宫切除、胎盘植入和介入治疗等方面均高于对照组（P＜0.05）。而术中出血量和围生儿结局无显著性差异（P＞0.05）。对凶险性前置胎盘进行规范化管理可明显减少孕产妇出血量,改善母儿结局。     

成年脑血管新生与抑郁症

成年脑神经元再生障碍是抑郁症发生的重要的细胞生物学基础之一。近年研究发现,成年脑血管新生与神经元再生存在密切关系,成年脑血管新生(angiogenesis)是指原有的血管萌生出新的微血管,再形成新的血管的过程。多种血管新生因子尤其是血管内皮生长因子(vascular endothelial growth factor,VEGF)不仅具有促血管新生作用,还具有神经营养和神经保护以及促神经元再生的作用,可能参与抑郁症的发生与恢复,该文就脑血管新生与抑郁症关系的最新研究进展进行综述。     

Therapeutic potential of plasma membrane-derived microparticles

In the past, plasma membrane-derived microparticles were considered “cellular dust.” According to the literature, circulating levels of microparticles are increased in several cardiovascular diseases associated with inflammation, suggesting that microparticles are linked to deleterious effects such as endothelial dysfunction or thrombosis. However, very recent studies have shown that under several conditions microparticles can transfer biological messages between cells. Indeed, microparticles act as vectors of key information to maintain cell homeostasis or to favor cell repair and induce angiogenesis. For instance, microparticles of platelet origin are able to repair myocardial injury after myocardial infarction. Also, we have shown that engineered microparticles generated from human activated/apoptotic T cells promote angiogenesis through the up-regulation of adhesion proteins and pro-angiogenic factors in human endothelial cells. Interestingly, the effects induced by these microparticles on the formation of capillary-like structures, expression of adhesion molecules, and pro-angiogenic factors are reversed after silencing of the Sonic Hedgehog (Shh) morphogen pathway. In addition, the same type of microparticles is able to induce neo-vascularization in an ischemic hindlimb model. These effects are, at least in part, mediated by Shh and nitric oxide production. Taking into consideration these results and the most recent data concerning the ability of microparticles to transmit genetic information between cells through mRNA transfer, it is plausible that plasma membrane-derived microparticles could serve as tools with veritable therapeutic potential.     

Gestational Exposure to Perfluorooctane Sulfonate Suppresses Immune Function in B6C3F1 Mice

Perfluorinated alkyl acids (PFAAs) are used in a multitude ofapplications and are categorized as high-production volume chemicalsproduced in quantities exceeding 10,000 lbs/year. As a result,widespread exposure has been documented in adults, children,and infants. It is generally accepted that children are moresensitive to the effects of xenobiotic exposures during fetaland postnatal periods of development; therefore, considerableefforts are required to investigate the potential impact ofa model PFAA, perfluorooctane sulfonate (PFOS) on children'simmunological health. Using the pairing of female C57BL/6N micewith male C3H/HeJ, developmental immunotoxicity was evaluatedin B6C3F1 pups following oral maternal exposure to PFOS on gestationsdays 1–17. Exposure levels included 0.1, 1, and 5 mg/kg/dayPFOS. Natural killer (NK) cell activity, SRBC IgM plaque assay,CD4/8 lymphocytic subpopulations, nitrite production in peritonealmacrophages, and body/organ weights were evaluated at 4 and8 weeks of age in F1 pups. No significant dose-responsive changesin maternal or pup body weights, flow cytometry, or macrophagefunction were observed, yet hepatomegaly was indicated in F1male pups at 4 weeks of age. Functional deficits were not evidentuntil 8 weeks of age when NK cell function and IgM productionwere significantly decreased. When compared with females, malepups were more sensitive to the effects of PFOS thereby establishinga no observed adverse effect level and low observed adverseeffect level of 0.1 and 1.0 mg/kg/day (males only) followingmaternal PFOS exposure level, respectively. This study establishesthat the developing immune system is sensitive to the effectsof PFOS and results in functional deficits in innate and humoralimmunity detectable at adulthood.     

Prenatal exposure to PFOS caused mitochondia‐mediated apoptosis in heart of weaned rat

Perfluorooctanyl sulfonate (PFOS), a cardiac toxicity compound, has been widely detected in the environment and in organisms. However, the toxic mechanism is not clear. Our previous study indicated that prenatal PFOS exposure led to swollen mitochondrial with vacuolar structure and loss of cristae in offsping's heart. The purpose of this study was to investigate the effect of PFOS on the apoptosis in developing heart and mitochondria‐mediated apoptosis pathway. Pregnant Sprague‐Dawley (SD) rats were exposed to PFOS at doses of 0.1, 0.6, and 2.0 mg/kg‐d and 0.05% Tween 80 as control by gavage from gestation day 2 (GD 2) to GD 21. Apoptosis, as well as expression of apoptosis related genes associated with mitochondrial‐mediated apoptosis pathway, including p53, bcl‐2, bax, cytochrome c, caspase‐9, and caspase‐3 were analyzed in heart tissues from weaned (postnatal day 21, PND 21) offspring. The results showed that prenatal PFOS exposure resulted in apoptosis in the offspring's heart. The mRNA and protein expression levels of p53, bax, cytochrome c, caspase‐9, and caspase‐3 in the offspring's heart were enhanced in various PFOS‐treated groups, meanwhile, the bcl‐2 expression levels were decreased. Our results indicated that prenatal PFOS exposure induced the apoptosis of weaned offspring rat heart tissue via mitochondria‐mediated apoptotic pathway. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 1082–1090, 2015.