应用流式细胞术研究甲基对硫磷对大鼠睾丸生精细胞的毒性作用

目的探讨有机磷农药甲基对硫磷对雄性大鼠的睾丸毒性作用。方法20只SD雄性大鼠（220～240g）随机分为对照组和低（1．2mg／kg）、中（6mg／kg）、高（30mg／kg）剂量甲基对硫磷组,灌胃染毒,容量为5ml／kg,每日1次,连续6周。染毒结束次日处死小鼠,用流式细胞仪对大鼠睾丸生精细胞进行分析。结果①高、中剂量甲基对硫磷组细胞凋亡率均显著高于对照组（P〈0．05或P〈0．01）;②与对照组相比,各剂量甲基对硫磷组1C细胞显著减少,2C细胞显著增加（P〈0．05或P〈0．01）;③与对照组相比,高剂量染毒组G0／G1期细胞比例显著降低,G2／M期细胞比例显著增加（P〈0．05或P〈0．01）。结论甲基对硫磷能够阻滞大鼠生精细胞的细胞周期进程,诱导生精细胞凋亡。     

Uptake and accumulation of selected herbicides by the freshwater alga scenedesmus

An algal toxicity bioassay using a continuous culture was investigated with respect to the herbicides dicryl and Bladex^® (cyanazine) in order to evaluate the effect of increasing dosages of applied herbicides upon growth, herbicide uptake, and herbicide accumulation in Scenedesmus. Growth patterns exhibited by Scenedesmus under continuous culture conditions reflected the ability of the alga to overcome inhibitory effects of the herbicides. Herbicides uptake by the alga attained maximum values in the presence of the lowest concentration of herbicides tested, at which levels maximum growth was also reached. Values for the accumulation factor tended to increase proportionally with the exposure time of the algal cell, but decreased as the concentration of herbicides increased.     

Absorption and elimination of14C-alpha- andgamma-chlordane by a freshwater alga,daphnid, and goldfish

The bioconcentration of chlordanes by fresh water food chain organisms gave values of 5,560 for algae, 24,000 for daphnids, and 162 for goldfish. The transfer of preexposed daphnids and goldfish to insecticide-free water resulted in up to 90% elimination of the absorbed/adsorbed dose in 7 and 11 days, respectively. Tissue distribution of chlordane suggests that the biliary pathway of excretion, along with elimination through the gill, kidney, and feces, may be important in the elimination of lipophilic hydrocarbons by fish.     

Speciation of aqueous methylmercury influences uptake by a freshwater alga (Selenastrum capricornutum)

Uptake of methylmercury (MeHg) by the alga Selenastrum capricornutum was measured in freshwater batch culture bioassays. The concentration of MeHg in the alga increased rapidly (within 15 min), reached a maximum by 6 h, and then declined because of growth dilution. The alga's rapid growth rate (doubling time, approximately 10 h) contributed to the importance of growth dilution. Conditional first-order rate constants were calculated for uptake (k1 = 6.95 x 10(-9) L/cell/h) and growth (kG = 0.07/h). A competitive synthetic ligand, disodium ethylenediaminetetra-acetate, formed strong complexes with MeHg and reduced MeHg uptake, consistent with the biotic ligand model. A conditional equilibrium formation constant (K) for the MeHg-algae complex was estimated to be approximately 10(16) and was used to model the influence of natural ligands on MeHg bioavailability. Model results suggested MeHg would be most bioavailable at concentrations of dissolved organic matter (DOM) less than 10 mg/L and increasingly unavailable at higher DOM concentrations for the specific humic acid modeled. Similarly, at molar concentrations of sulfide (and, possibly, metal-sulfide clusters) equal to approximately half the MeHg concentration, MeHg was predicted to be unavailable to algae because of the formation of strong 2:1 MeHg-sulfide complexes.     

甲醛吸入对小鼠免疫系统毒性作用

目的通过吸入甲醛（formaldehyde,FA）染毒小鼠观察其免疫损伤作用。方法选用健康清洁级昆明种小鼠30只,随机分成5组（即阴性对照组1,3,5 mg/m3染毒组和阳性对照组）,每组6只,用静式吸入染毒方式染毒14d处死后,计算脾脏系数、胸腺系数;测定脾脏和胸腺CD3含量、CD4含量、CD8含量;测定巨噬细胞吞噬功能、迟发超敏反应、抗体生成细胞数及脾脏淋巴细胞功能转化。结果甲醛吸入染毒可以引起小鼠脾脏系数、胸腺系数减小（P〈0.05或P〈0.01）;脾脏和胸腺CD3、CD4、CD8含量降低,CD4/CD8明显增大（P〈0.05或P〈0.01）;脾淋巴细胞转化功能、迟发变态反应强度、抗体生成细胞数、巨噬细胞吞噬功能均随染毒剂量的升高而下降（P〈0.05或P〈0.01）。结论吸入甲醛可导致小鼠免疫系统的全面损伤。     

Development of an improved rapid enzyme inhibition bioassay with marine and freshwater microalgae using flow cytometry

A rapid toxicity test based on inhibition of esterase activity in marine and freshwater microalgae (Selenastrum capricornutum, Chlorella sp., Dunaliella tertiolecta, Phaeodactylum tricornutum, Tetraselmis sp., Entomoneis cf. punctulata, Nitzschia cf. paleacea) was developed using flow cytometry. Uptake of fluorescein diacetate (FDA) was optimized for each species by varying the substrate concentration, incubation time, and media pH. Propidium iodide (PI) was utilized to assess membrane integrity. The optimized FDA/PI staining procedure was then used to assess the toxicity of copper in short-term exposures (1–24 h). Esterase activity was a sensitive indicator of copper toxicity in S. capricornutum and E. cf. punctulata. As copper concentrations increased, esterase activity decreased in a concentration-dependent manner. The 3- and 24-h EC₅₀ values (based on mean activity states) were 112 μg Cu L⁻¹ (95% confidence limits 88–143) and 51 μg Cu L⁻¹ (95% confidence limits 38–70) for S. capricornutum and 47 μg Cu L⁻¹ (95% confidence limits 43–51) and 9.1 μg Cu L⁻¹ (95% confidence limits 7.6–11) for E. cf. punctulata, respectively. This enzyme inhibition endpoint showed similar sensitivity to chronic growth rate inhibition in E. cf. punctulata (48-h and 72-h EC₅₀ values of 17 and 18 μg L⁻¹, respectively) but was less sensitive compared to growth for S. capricornutum (48-h and 72-h EC₅₀ values of 4.9 and 7.5 μg L⁻¹, respectively). For the other five species tested, inhibition of FDA fluorescence was relatively insensitive to copper, even at copper concentrations that severely inhibited cell division rate. These short-term bioassays that detect sublethal endpoints may provide a more rapid and cost-effective way of monitoring contaminant impacts in natural waters. Received: 2 July 2000/Accepted: 15 December 2000     

Bioavailability and effect of pirimicarb on Daphnia magna in a laboratory freshwater/sediment system

In tests with newborn and one-week-old Daphnia magna, 48-h EC₅₀ values of 21–24 g/L and 16 g/L pirimicarb, respectively, were found. Older animals thus were as sensitive to pirimicarb as newborn animals. In an experiment with sediment included in the test system, all mother animals survived for 72 h at 20 g/L, and the number of offspring was not reduced relatively to the control. Addition of sediment thus reduced the toxicity of pirimicarb toward Daphnia magna.Pirimicarb was accumulated 12–16 times (5–7% of total) in the sediment, but the water concentrations of pirimicarb were not reduced significantly during the experiment, due to the small amount of sediment used. Accumulation in the sediment was found independent of the water concentration used. This was also the case with bioaccumulation in Daphnia magna, where a bioaccumulation factor of 31–37 was found on a dry weight basis. In water without sediment a BCF of 50 was found. Addition of sediment also reduced the accumulation of pirimicarb in the daphnids. The reduced bioavailability of pirimicarb may derive from humic acid and related compounds released from the sediment.     

应用流式细胞术研究大蒜粉对小鼠巨噬细胞吞噬功能的影响

目的建立流式细胞术检测小鼠巨噬细胞吞噬功能的方法,探讨其在保健食品增强免疫力功能评价中的意义。方法昆明种小鼠随机分为4组,其中3组分别按0.11、0.22、0.66 g/(kg.BW)低、中、高3个剂量的大蒜粉片灌胃,阴性对照组给予纯净水,连续30 d后,分离小鼠腹腔巨噬细胞,与调理后的荧光微球孵育后,用流式细胞仪检测FITC荧光阳性巨噬细胞数来计算巨噬细胞吞噬率,观察大蒜粉对腹腔巨噬细胞吞噬荧光微球功能的影响,同时用ConA诱导的小鼠脾淋巴细胞转化试验及小鼠迟发型变态反应试验观察大蒜粉对小鼠细胞免疫功能的影响。结果用荧光微球技术结合流式细胞仪检测实验组和对照组的小鼠腹腔巨噬细胞吞噬荧光微球功能,结果显示,实验组(大蒜粉)能明显提高小鼠巨噬细胞吞噬功能,其低、中、高3个剂量组吞噬百分率分别为(24.42±4.10)%、(23.82±4.55)%、(29.55±5.81)%,吞噬指数分别为0.36±0.07、0.35±0.08、0.47±0.11,均高于阴性对照组[(17.32±4.80)%,0.24±0.07](P<0.01);各剂量组迟发型变态反应能力均升高,低剂量组淋巴细胞转化值增高,均高于阴性对照组,差异有统计学意义(P<0.05或P<0.01)。结论流式细胞仪检测小鼠腹腔巨噬细胞吞噬功能的方法具有简便、快捷、重复性好以及准确率高的特点,适合在保健食品增强免疫力功能评价中推广应用。     

Application of flow cytometry and PMA-qPCR to distinguish between membrane intact and membrane compromised bacteria cells in an aquatic milieu

The paper compares two methods of distinguishing between alive and dead cells by differentiation on the basis of their membrane structure: LIVE/DEAD flow cytometry and PMA-qPCR. LIVE/DEAD flow cytometry was established using the LIVE/DEAD^® BacLight™ Bacterial Viability Kit with different ratios of Legionella pneumophila and Escherichia coli cells with intact and compromised membranes (heat treated). The PMA-qPCR method was tested and modified, and results were compared with those from LIVE/DEAD flow cytometry using L. pneumophila cells.Ratios of membrane intact to membrane compromised cells were well shown by LIVE/DEAD flow cytometry in all combinations. PMA-qPCR seems to work best in even mixed ratios (1:1) of intact and compromised cells. In other respects, we noticed an overestimation of intact cells in the samples which contained a high percentage of membrane compromised cells, and an underestimation of intact cells in samples with a small percentage of membrane compromised cells. However, looking at total counts instead of ratios, the results were within an order of magnitude. This implies that the use of PMA-qPCR is appropriate only for a qualitative analysis to monitor the success of a process such as disinfection. Furthermore, we were able to assess that both methods have advantages and disadvantages: LIVE/DEAD flow cytometry as applied in this study works well on some bacteria monocultures, but does not distinguish between bacteria species. The PMA-qPCR method allows the possibility of distinguishing between membrane intact cells and membrane compromised cells and can be used to screen for specific bacteria.     

Toxic and sublethal effects of carbaryl on a freshwater catfish,Mystus vittatus (Bloch)

The effects of carbaryl (1-naphthalenyl methylcarbamate), commonly used in agricultural operations, have been studied with reference to survival, behavior, food intake, growth, and conversion efficiency of the catfishMystus vittatus. At a concentration of 32.5 ppm, carbaryl caused 100% mortality within 24 hr; the 72 hr LC₅₀ was 17.5 ppm. At concentrations of 12.5 ppm and below, it caused no mortalities within 72 hr. But such sublethal concentrations accelerated the swimming activity and increased the frequency of opercular beats. The latter response was dose-dependent. These behavioral changes were the immediate response to the toxicant and were indicators of possible stress. A 27-day exposure to sublethal concentrations of carbaryl led to a decrease in feeding rate and growth rate. The latter decreased from 10.15 mg/g/day (freshwater) to 2.84 mg/g/day (12.5 ppm). The reduced growth and conversion efficiency may be due to the expenditure of more energy for the purpose of maintenance. Therefore, the insecticide is considered to be a metabolic Stressor.     

Toxic effects of Streptomyces griseus spores and exudate on gill pathology of freshwater fish

Many unexplained fish-kills in British waters are considered microbial in origin and a large proportion of field sites contains elevated concentrations of filamentous actinobacteria. The present study has shown that a strain of Streptomyces griseus, isolated from field sites, elicits pathological changes to the gills of fish under laboratory conditions which mirror those found in situ. These changes include hyperplasia leading to fusion of the secondary lamellae and loss of microridging on the filamental epithelium of the primary lamellae. Juveniles of up to six fish species were exposed to spore suspensions or exudate of S. griseus in the range of 1 x 10(2)-1 x 10(6)spores ml(-1) for up to 96 h. The exudate was more potent than the spores and there was a positive correlation between exudate concentration and the rate and extent of fish gill pathology with bream and rainbow trout being more sensitive than carp, tench and roach. The results are discussed in the context of recognising and managing potential fish mortalities caused by microbial toxins.     

Estimating the effect of a predictor measured by two informants on a continuous outcome: a comparison of methods

Investigators sometimes use information obtained from multiple informants about a given variable. We focus on estimating the effect of a predictor on a continuous outcome, when that (true) predictor cannot be observed directly but is measured by 2 informants. We describe various approaches to using information from 2 informants to estimate a regression or correlation coefficient for the effect of the (true) predictor on the outcome. These approaches include methods we refer to as single informant, simple average, optimal weighted average, principal components analysis, and classical measurement error. Each of these 5 methods effectively uses a weighted average of the informants' reports as a proxy for the true predictor in calculating the correlation or regression coefficient. We compare the performance of these methods in simulation experiments that assume a rounded congeneric measurement model for the relationship between the informants' reports and a true predictor that is a mixture of zeros and positively distributed continuous values. We also compare the methods' performance in a real data example-the relationship between vigorous physical activity (the predictor) and body mass index (the continuous outcome). The results of the simulations and the example suggest that the simple average is a reasonable choice when there are only 2 informants.     

流式细胞术检测宫颈细胞DNA倍体在宫颈病变中的应用

目的:探讨流式细胞术检测宫颈细胞DNA倍体在宫颈病变中的应用价值。方法:对290例患者的液基细胞学检测后剩余细胞行流式细胞术DNA倍体分析,其中非典型鳞状上皮增生(ASCUS)120例、低度宫颈上皮内瘤变(LSIL)90例、高度宫颈上皮内瘤变(HSIL)60例、鳞状上皮癌(SCC)20例。结果:①异倍体在ASCUS组、LSIL组、HSIL组、SCC组中检出率分别为3.3%、31.1%、85.0%、96.7%。②LSIL、HSIL、SCC 3组的异倍体率与ASCUS组比较有显著性差异(P<0.05);HSIL、SCC 2组的异倍体率与LSIL组比较差异显著(P<0.05);HSIL、SCC 2组的异倍体率之间无统计学差异(P>0.05)。结论:DNA倍体分析可以作为宫颈病变早期的筛查手段。     

镉对大鼠雌性性腺毒性研究

目的　镉的雌性性腺生殖毒性研究颇少见。本文通过亚慢性镉染毒,观察了镉对大鼠的雌性性腺毒性。方法　随机将动物分四组,染镉剂量分别为１ 、０－５ 、０－２５ 和０ ｍｇ／ｋｇ 体重。腹腔注射染毒,每日一次,每周５ 天,连续６ 周。结果　镉染毒各剂量组大鼠卵巢镉含量均显著高于对照组;高、中剂量染毒组大鼠动情周期均比对照组显著延长;高、中剂量染毒组大鼠闭锁卵泡构成比显著高于对照组。结论　卵巢同肾脏一样,也是镉的重要的靶器官之一。镉的雌性性腺生殖毒性可表现为动情周期的明显延长,卵巢细胞生长发育过程的明显障碍     

氟砷染毒对大鼠生殖发育毒性的研究

为探讨氟砷染毒对生殖功能和子代发育的影响,采用两代一窝繁殖实验的方法,观察Ｗｉｓｔａｒ大鼠暴露于氟（ＮａＦ）砷（Ａｓ２Ｏ３）后其生殖功能和子代生长发育的变化,以及卵巢的病理改变。结果表明,随着染毒剂量的增加,受孕率、正常分娩率、出生存活率和哺育成活率随之降低;如高剂量组受孕率Ｆ０和Ｆ１代分别为７３．０８％和６１．５４％,而对照组为９２．３１％和８４．６２％;而体氟和体砷显著增加;高剂量组子代体重明     

Influence of oligomeric silicic and humic acids on aluminum accumulation in a freshwater grazing invertebrate

This study examined the influence of oligomeric silicic acid and humic acid on aluminum in the water column and its accumulation in the freshwater snail Lymnaea stagnalis. Forty-eight hours after addition of Al (500 microg L(-1)), 83% of the metal was lost from the water column. This loss was reduced by oligomeric silica (20 mg L(-1)) and by humic acid (10 mg L(-1)). Aluminum accumulated in the digestive gland and, to a lesser extent, in the remaining soft tissues, and this accumulation was reduced by oligomeric silica. In the presence of humic acid, Al accumulation in the digestive gland was unaffected, though less was accumulated in the remaining tissues. Snails accumulated Si preferentially in the digestive gland and this accumulation was increased in the presence of added Al. Thus, both oligomeric silica and humic acid influence Al bioavailability and Si is upregulated in the digestive gland in the presence of Al.