Assessment of fitness for purpose of an insect bioassay using the desert locust (Schistocerca gregaria L.) for the detection of paralytic shellfish toxins in shellfish flesh.

We have developed a bioassay using 5th instar desert locusts (Schistocerca gregaria L.) for the detection of saxitoxin-the paralytic shellfish poison in shellfish flesh. The bioassay procedure is to inject 10 locusts with a shellfish extract, and assess their conditions at time points up to 2h post injection, looking for an endpoint of paralysis. From the proportion responding, the equivalent dose of pure saxitoxin could be estimated. Performance characteristics of the bioassay were assessed using shellfish samples spiked with saxitoxin, and we found the bioassay could detect and quantify toxin levels in the range of regulatory relevance. Relative toxicities of selected saxitoxin analogues differed from those reported in mammalian systems. Variation for repeatability conditions was acceptable but variation was higher under reproducibility conditions. This was related to (a) batches of insects from different suppliers, (b) different operators, and (c) different observers assessing the endpoint. We also noted adverse reactions with some shellfish species. These problems may be resolved by further refinement of the method and operator training, before formal validation. Nevertheless, we suggest the method potentially offers a simple, ethically acceptable, broad-specificity functional bioassay, which is desirable in any toxin-monitoring programme.     

Purple sweet potato anthocyanins attenuate hepatic lipid accumulation through activating adenosine monophosphate–activated protein kinase in human HepG2 cells and obese mice

Purple sweet potato is a functional food rich in anthocyanins that possess disease-preventive properties. Anthocyanins are known to possess potent antidiabetic properties. However, the effect of the anthocyanin fraction (AF) from purple sweet potato on hepatic lipid metabolism remains unclear. Our hypothesis is that AF inhibits hepatic lipid accumulation through the activation of adenosine monophosphate–activated protein kinase (AMPK) signaling pathways in vitro and in vivo. In this study, we evaluated body weight, liver histology, and hepatic lipid content in high-fat diet (HFD)–fed ICR mice treated with AF. In addition, we characterized the underlying mechanism of AF's effects in HepG2 hepatocytes through Western blot analysis. Anthocyanin fraction (200 mg/kg per day) reduced weight gain and hepatic triglyceride accumulation and improved serum lipid parameters in mice fed an HFD for 4 weeks. Anthocyanin fraction significantly increased the phosphorylation of AMPK and acetyl-coenzyme A carboxylase (ACC) in the liver and HepG2 hepatocytes. In addition, AF down-regulated the levels of sterol regulatory element-binding protein 1 and its target genes including ACC and fatty acid synthase (FAS). The specific AMPK inhibitor compound C attenuated the effects of AF on the expression of lipid metabolism–related proteins such as SREBP-1 and FAS in HepG2 hepatocytes. The beneficial effects of AF on HFD-induced hepatic lipid accumulation are thus mediated through AMPK signaling pathways, suggesting a potential target for the prevention of obesity.     

Surveillance of algal toxins in shellfish from Scottish waters.

Shellfish samples were collected from coastal and offshore aquaculture sites and harvesting areas in Scottish waters between March 2003 and September 2004. Samples were analysed for the presence of algal toxins using traditional mouse bioassays for the detection of paralytic shellfish poisoning (PSP) toxins and diarrhetic shellfish poisoning (DSP) toxins; immuno-lateral flow chromatography for the detection of PSP toxins in the form of the Jellett Rapid Test; high-performance liquid chromatography (HPLC) with UV diode-array for the detection of amnesic shellfish poisoning (ASP) toxins; and liquid chromatography with mass spectrometry (LC-MS) for the detection of multiple lipophilic shellfish toxins (LSTs) including pectenotoxins (PTXs), yessotoxins (YTXs), azaspiracids (AZAs) and toxins from the 'traditional' DSP toxin group, okadaic acid (OA) and dinophysistoxins (DTXs). In order to investigate the presence of OA esters, alkaline hydrolysis was performed. All toxin groups were detected with a geographically widespread distribution. ASP toxins were the most prevalent occurring in 69% of samples. Using the PSP mouse bioassay, PSP toxins were detected in 5% of shellfish samples from coastal waters around the islands and the east coast. The Jellett Rapid Test for PSP toxins revealed a wider distribution (24% of samples) including the west coast of Scotland. Toxins from the 'traditional' DSP toxin group (OA/DTXs) and/or other LST groups (PTXs, YTXs and AZAs) were detected by LC-MS in 63% of the shellfish analysed. PSP, ASP toxins and LSTs occurred concurrently in a limited sample set, highlighting the importance of using methods capable of detecting multiple algal toxin groups in Scottish shellfish monitoring programmes.     

丙戊酸钠联合帕利哌酮治疗精神分裂症的疗效观察

目的研究丙戊酸钠联合帕利哌酮治疗精神分裂症的临床疗效。方法选择2014年4月—2016年1月到北京市昌平区中西医结合医院诊治的精神分裂症患者104例,随机分为对照组和治疗组,每组各52例。对照组口服帕利哌酮缓释片,起始剂量为6 mg/d,1周内根据病情将剂量调整为6~9 mg/d。治疗组在对照组治疗基础上口服丙戊酸钠缓释片,起始剂量为0.5 g/d,最大剂量为1.5~2.0 g/d,可根据病情酌情加减。两组患者均持续治疗12周。观察两组的临床疗效,同时比较两组治疗前后阴性和阳性症状量表(PANSS)评分和个人和社会功能量表(PSP)评分的变化情况。结果治疗后,对照组和治疗组的总有效率分别为80.77%、94.23%,两组比较差异有统计学意义(P0.05)治疗后6、12周,两组阳性症状评分、阴性症状评分、精神病理评分、PANSS总分显著下降,PSP评分显著升高,同组治疗前后差异有统计学意义(P0.05),且治疗组这些评分的改善程度优于对照组,两组比较差异具有统计学意义(P0.05)。结论丙戊酸钠联合帕利哌酮治疗精神分裂症疗效显著,有效缓解临床症状,改善社会功能,安全性好,具有一定的临床推广应用价值。     

Study of paralytic shellfish poisoning toxin profile in shellfish from the Mediterranean shore of Morocco

Since 1992, a monitoring program for bivalve molluscs contaminated by algal toxins was established at different stations along the Mediterranean Moroccan shores. The monitored stations were tested every 2 weeks. The presence of toxicity was determined using the mouse bioassay method. Toxin profile was carried out by HPLC/FD in selected contaminated tissues. According to the outcomes of this surveillance from 1994 to 1999, reliable information on toxicity of shellfish was obtained. They indicate that PSP is a recurrent toxicity in molluscs along the Mediterranean shore of Morocco. It has been noted a difference of PSP accumulation among individual shellfish. The cockle (Achanthocardia tuberculatum) presents toxicity throughout the year, while other specimens from the same area such as clam (Callista chione), warty venus (Venus gallina) and marine beans (Donax trunculus) accumulate it seasonally from January to April, after which they depurate the toxin. Moreover, the study of toxin profiles among individual shellfish was undertaken. It was found that shellfish presented a complex profile pointing to contamination by Gymnodinium catenatum.     

First evidence of “paralytic shellfish toxins” and cylindrospermopsin in a Mexican freshwater system, Lago Catemaco, and apparent bioaccumulation of the toxins in “tegogolo” snails (Pomacea patula catemacensis)

Exposure to cyanobacterial toxins in freshwater systems, including both direct (e.g., drinking water) and indirect (e.g., bioaccumulation in food webs) routes, is emerging as a potentially significant threat to human health. We investigated cyanobacterial toxins, specifically cylindrospermopsin (CYN), the microcystins (MCYST) and the “paralytic shellfish toxins” (PST), in Lago Catemaco (Veracruz, Mexico). Lago Catemaco is a tropical lake dominated by Cylindrospermopsis, specifically identified as Cylindrospermopsis catemaco and Cylindrospermopsis philippinensis, and characterized by an abundant, endemic species of snail (Pomacea patula catemacensis), known as “tegogolos,” that is both consumed locally and commercially important. Samples of water, including dissolved and particulate fractions, as well as extracts of tegogolos, were screened using highly specific and sensitive ELISA. ELISA identified CYN and PST at low concentrations in only one sample of seston; however, both toxins were detected at appreciable quantities in tegogolos. Calculated bioaccumulation factors (BAF) support bioaccumulation of both toxins in tegogolos. The presence of CYN in the phytoplankton was further confirmed by HPLC-UV and LC-MS, following concentration and extraction of algal cells, but the toxin could not be confirmed by these methods in tegogolos. These data represent the first published evidence for CYN and the PST in Lago Catemaco and, indeed, for any freshwater system in Mexico. Identification of the apparent bioaccumulation of these toxins in tegogolos may suggest the need to further our understanding of the transfer of cyanobacterial toxins in freshwater food webs as it relates to human health.     

Retention and tissue damage of PSP and NSP toxins in shrimp: Is cultured shrimp a potential vector of toxins to human population?

Toxic microalgae outbreaks have caused significant economic losses in the Mexican aquaculture industry. Blooms that involve PSP and NSP phycotoxins are two of the most dangerous, causing harmful effects to the environment, economy and public health. The exact metabolic mechanism of these toxins in shrimp still remains unknown. Because shrimp consume microalgae their edible tissues are clearly possible vectors for human toxic syndrome. This study examined and verified the toxicological effects for white leg shrimp (Litopenaeus vannamei) exposed to different cell densities of Gymnodinium catenatum and Karenia brevis. Acute assays demonstrated good survival rates of shrimp at low densities of dinoflagellates (10³ cell/L), while mortality and abnormal behavior were observed with higher densities (>10⁴ cell/L). Chronic assays showed significant differences in survival rates, percentage of feed and weight gain of organisms exposed to the dinoflagellates with respect to controls. Furthermore, PSP and NSP toxins were detected in all the edible tissues. Gastric glands and muscle retained toxins for a longer period of time compared to other tissues, even after a depuration period. Histology damages were observed in the heart, gastric gland and brain. This study strongly supports that shrimp represent a potential risk for humans as unconventional vectors of phycotoxins.     

钝顶螺旋藻多糖抗病毒作用的实验研究

目的探讨钝顶螺旋藻多糖(polysaccharide fromSpirulina platensis,PSP)抗单纯疱疹病毒及乙型肝炎病毒的作用及可能机制,为进一步开发该药提供理论依据。方法以不同剂量的PSP分别作用于HSV-1及HSV-2病毒复制周期的各个环节,以病毒半数感染量(TCID50),细胞病变效应(CPE),蚀斑形成单位(PFU),MTT法作为评价指标,判断PSP的抗病毒效果;ELISA法定量检测PSP对HepG2 2.2.15细胞HbsAg,HBeAg分泌的影响;FQ-PCR检测PSP对HBV-DNA合成的影响。结果PSP对Vero细胞及HepG2 2.2.15细胞毒性极低,对HSV-1及HSV-2均无直接灭活作用,可阻滞HSV-1及HSV-2病毒的吸附并抑制感染细胞内病毒的复制,但不影响病毒的释放。在HepG2 2.2.15细胞培养中PSP可显著抑制HB-sAg、HBeAg的分泌以及HBV-DNA的合成,并具有量效和时效关系。结论PSP抗HSV-1及HSV-2病毒作用的机制与抑制病毒吸附和感染细胞内病毒的生物合成有关,而PSP抗HBV作用的机制则与抑制HBV抗原分泌及病毒DNA复制有关。     

Effects of polysaccharide peptides from COV-1 strain of Coriolus versicolor on glutathione and glutathione-related enzymes in the mouse.

The effects of polysaccharide peptide (PSP), an immunomodulator isolated from Coriolus versicolor COV-1, on glutathione (GSH) and GSH-related enzymes was investigated in C57 mouse. Administration of PSP (1-4 micromole/kg, i.p.) produced a transient, dose-dependent depletion (10-37%) of hepatic GSH, with no effect on serum glutamic-pyruvic transaminase (SGPT) activity. Blood GSH was depleted (6-25%) at 3 h, followed by a rebound increase above the control GSH level (20%) at 18 h. The GSSG/GSH ratio, a measure of oxidative stress, was increased 3 h after PSP treatment but returned to normal levels at 24 h. Sub-chronic treatment of PSP (1-4 micromole/kg/day, i.p.) for seven days did not produce any significant changes in hepatic GSH levels and the GSSG/GSH ratio when measured 24 h after the final dose of PSP. PSP had little effect on glutathione transferase (GST), glutathione reductase (GSSG reductase) and glutathione peroxidase (GPX) activities in the liver. However, a dose-dependent increase in blood GPX activity (30-48%) was observed at 3h, which coincided with the increase in the GSSG/GSH ratio. The increase in blood GPX activity may be a responsive measure to deal with the transient oxidative stress induced by PSP treatment. The results showed that PSP only caused a transient perturbation on hepatic glutathione without affecting the GSH-related enzymes such as GST, GSSG reductase and GPX. The observed changes in blood GSH simply reflected the intra-organ translocation of glutathione, as the glutathione-related enzymes were not significantly affected by PSP treatment.