基于小白鼠实验的新型膨胀阻燃低密度聚乙烯复合材料烟气毒性研究(英文)

利用小白鼠试验来研究新型阻燃低密度聚乙烯(LDPE)复合材料的烟气毒性,探寻材料烟气毒性最大不至死浓度,根据相关标准判断材料毒性所属级别,并比较研究不同燃烧状况下阻燃LDPE复合材料产烟毒性.从烟气毒性实验可知,有焰燃烧比无焰燃烧具有较小的烟气毒性.同时利用火灾性能指数和火灾发展指数对阻燃LDPE复合材料的火灾安全性进行评价.研究结果有助于优化设计环境友好、综合性能优良的阻燃低密度聚乙烯复合材料.

以小白鼠实验为背景材料开发生物试题

对以小白鼠实验为题材开发的生物试题进行了简要归纳。

四川省首次发现由实验大白鼠引起的人类肾综合征出血热

目的：了解实验大白鼠及其接触者感染肾综合征出血热（ＨＦＲＳ）情况。方法：间接免疫荧光抗体试验（ＩＦＡ）。结果：某医学研究所现养和已售出的大白鼠中，汉坦病毒抗原阳性率分别为５１．２５％（４１／８０）和４２．５０％（１７／４０），现养大白鼠抗体阳性率为４５．００％（３６／８０）；与这批大白鼠密切接触者血清抗体阳性率为３２．２０％（１９／５９），其中１人发生ＨＦＲＳ；非接触者血清抗体阳性率为６．１２％（３／４９）。结论：首次证实我省存在由非ＨＦＲＳ实验室的实验大白鼠引起的ＨＦＲＳ，在暴露于这些大白鼠的人员中，汉坦病毒隐性感染率也较高。

实验小白鼠肝脏、肌肉5种微量元素含量测定

本研究采用火焰原子吸收分光光度法对实验小白鼠肝脏、腿肌和胸肌中Fe、Co、Mn、Cu、Cr五种微量元素含量分别进行测定,结果如下:肝脏Fe:692.83±150.28mg·kg-1;Co:189.25±32.11mg·kg-1;Mn:12.97±3.78mg·kg-1;Cu:60.21±6.65mg·kg-1;Cr:51.68±4.83mg·kg-1:肌肉Fe:391.00±83.51mg·kg-1;Co:201.06±14.96mg·kg-1;Mn:15.68±3.65mg·kg-1;Cu:50.61±8.905mg·kg-1;Cr:48.31±5.16mg·kg-1。小白鼠肝脏、肌肉Fe、Co、Mn、Cu、Cr的含量测定为该五种微量元素中毒或缺乏症提供依据。同时也为实验小白鼠肝脏、肌肉Fe、Co、Mn、Cu、Cr的测定提供参考数据。

复合益生菌制剂对小白鼠生长性能、肠道微生物菌群结构及血清生化指标的影响

为探讨复合益生菌制剂对小白鼠生长性能、肠道微生物菌群结构及血清生化指标的影响,采用单因素随机设计试验,选择体质量为(20±2.5)g健康实验昆明系小白鼠360只随机分成4个组,每个组9个重复,每个重复10只,1组饲喂基础日粮为空白对照组,试验2、3、4组分别在基础日粮中添加0.25%、0.5%、1.0%的复合益生菌制剂,试验期为28 d。结果显示:(1)试验3、4组小白鼠平均日增重较1组相比分别提高31.9%、29.8%(P<0.05),试验2、3、4组平均采食量均高于1组(P>0.05),试验3、4组料重比较1组相比分别降低16.2%、15.7%(P<0.05)。(2)试验3、4组粪便中大肠杆菌的含量较1组相比分别降低19.2%、18.5%(P<0.05),试验2、3、4组粪便中沙门菌含量均低于1组(P>0.05),试验3,4组粪便中的双歧杆菌和乳酸杆菌含量较1组相比分别提高31.9%、31.5%、16.8%、16.2%(P<0.05)。(3)试验3、4组血清中总蛋白(TP)含量较1组相比分别提高14.7%、14.4%(P<0.05),试验2、3、4组血清中的白蛋白(ALB)含量均高于1组(P>0.05),试验2、3、4组血清中的天门冬氨酸氨基转移酶(GOT)含量均低于1组(P>0.05),试验3、4组血清中谷氨酸氨基转移酶(GPT)、血尿素氮(BUN)含量较1组相比分别降低11.1%、11%、21.7%、21.3%(P<0.05)。综上,0.5%复合益生菌制剂添加可以提高小白鼠的生长性能,改善肠道微生物菌群结构,提高肝肾代谢功能。

芒果叶中芒果甙的提取及其镇痛作用的研究

目的对芒果叶中芒果甙的提取工艺及镇痛作用进行探讨。方法采用乙醇提取、乙酸乙酯等有机溶剂从芒果叶中反复萃取芒果甙,得到淡黄色物质,并对该物质进行化学定性分析和小白鼠镇痛实验(芒果甙组),设阿司匹林组和生理盐水组进行对照分析。结果该提取物中主要含有芒果甙。经对小白鼠镇痛试验,芒果甙对扭体法致小白鼠疼痛的镇痛作用显著,与阿司匹林组和生理盐水组比较差异有显著性(P<0.01或0.05);芒果甙组在分别给药后20min、30min、60min痛阈潜伏期比生理盐水组和阿司匹林组明显延长(P均<0.01)。结论芒果叶中富含芒果甙,对小白鼠具有显著的镇痛作用。

记忆能遗传吗

最近,日本一家遗传学杂志披露了一个令人匪夷所思的消息,日本生物学界将要正式发布新名词:"国木实验".这是因为近年来世界各国有关生物基因工程,特别是人类遗传密码的破译取得突破性进展,生物科技向前迈进了一大步后,有些实验科学可能会突然失去意义的情况下,不得不决定提前发布.

不能忽视“感冒”(二)

最近我家遇到一件不幸的事,我怎么都弄不明白为什么感冒会转成了“流行性出血热”。我爱人是个下岗职工 现在干个体,经营小商品,每天吃、喝在外,异常辛苦。好不容易生活有了改善,却得了一场大感冒,浑身酸痛、头痛,甚至连眼睛都痛,高烧不退,用了许多贵重的抗生素,一点用也没有,反而发生了口鼻出血,皮肤上亦有出血斑。更叫人意想不到的是在退烧时,突然小便减少。

Chromatin-binding in vivo of the erythroid kruppel-like factor,EKLF,in the murine globin loci

EKLF is an erythroid-specific, zinc finger-containing transcription factor essential for the activation of the mammalian beta globin gene in erythroid cells of definitive lineage. We have prepared a polyclonal anti-mouse EKLF antibody suitable for Western blotting and immunoprecipitation （IP） qualities, and used it to define the expression patterns of the EKLF protein during mouse erythroid development. We have also used this antibody for the chromatin-immunoprecipitation （CHIP） assay. EKLF was found to bind in vivo at both the mouse beta-major-globin promoter and the HS2 site of beta-LCR in the mouse erythroleukemia cells （MEL） in a DMSO-inducible manner. The DMSO-induced bindings of EKLF as well as three other proteins, namely, RNA polymerase Ⅱ, acetylated histone H3, and methylated histone H3, were not abolished but significantly lowered in CB3, a MEL-derived cell line with null-expression of p45/NF-E2, an erythroid-enriched factor needed for activation of the mammalian globin loci. Interestingly, binding of EKLF in vivo was also detected in the mouse alpha-like globin locus, at the adult alpha globin promoter and its far upstream regulatory element alpha-MRE （HS26）. This study provides direct evidence for EKLF-binding in vivo at the major regulatory elements of the mouse beta-like globin gene clusters the data also have interesting implications with respect to the role of EKLF-chromatin interaction in mammalian globin gene regulation.

Changes of CREB in rat hippocampus, prefrontal cortex and nucleus accumbens during three phases of morphine induced conditioned place preference in rats

Objective: To investigate the changes in CREB (cAMP response element binding protein) in hippocampus, PFC (prefrontal cortex) and NAc (nucleus accumbens) during three phases of morphine induced CPP (conditioned place preference) in rats, and to elucidate the role of CREB during the progress of conditioned place preference. Methods: Morphine induced CPP acquisition, extinction and drug primed reinstatement model was established, and CREB expression in each brain area was measured by Western Blot methods. Results: Eight alternating injections of morphine (10 mg/kg) induced CPP, and 8 d saline extinction training that extinguished CPP. CPP was reinstated following a priming injection of morphine (2.5 mg/kg). During the phases of CPP acquisition and reinstatement, the level of CREB expression was significantly changed in different brain areas. Conclusion: It was proved that CPP model can be used as an effective tool to investigate the mechanisms underlying drug-induced reinstatement of drug seeking after extinction, and that morphine induced CPP and drug primed reinstatement may involve acti-vation of the transcription factor CREB in several brain areas, suggesting that the CREB and its target gene regulation pathway may mediate the basic mechanism underlying opioid dependence and its drug seeking behavior.

Generation of the regulatory protein rtTA transgenic mice

AIM: To translate Tet-on system into a conditional mouse model, in which hepatitis B or C virus (HBV or HCV) gene could be spatiotemporally expressed to overcome 'immune tolerance' formed during the embryonic development and 'immune escape' against hepatitis virus antigen(s), an effector mouse, carrying the reverse tetracycline-responsive transcriptional activator (rtTA) gene under the tight control of liver-specific human apoE promoter, is required to be generated. METHODS: To address this end, rtTA fragment amplified by PCR was effectively inserted into the vector of pLiv.7 containing apoE promoter to create the rtTA expressing vector, I.e., pApoE-rtTA. ApoE-rtTA transgenic fragment (-6.9 kb) released from pApoE-rtTA was transferred into mice by pronucleus injection, followed by obtaining one transgene (+) founder animal from microinjection through PCR and Southern blot analysis.RESULTS: rtTA transgene which could be transmitted to subsequent generation (F1) derived from founder was expressed in a liver-specific fashion. CONCLUSION: Taken together, these findings demonstrate that rtTA transgenic mice, in which rtTA expression is appropriately targeted to the murine liver, are successfully produced, which lays a solid foundation to 'off-on-off' regulate expression of target gene (s) (e.g., HBV and/or HCV) in transgenic mice mediated by Tet-on system.

Uptake of albumin nanoparticle surface modified with glycyrrhizin by primary cultured rat hepatocytes

AIM: To investigate the uptake difference between bovine serum albumin nanoparticle (BSA-NP) and bovine serum albumin nanoparticles with their surface modified byglycyrrhizin (BSA-NP-GL) and to develop a novel hepatocyte targeting BSA-NP-GL based on active targeting technology mediated by specific binding site of GL on rat cellular membrane. METHODS: Calcein loaded bovine serum albumin nanoparticles (Cal-BSA-NP) were prepared by desolvation process. Glycyrrhizin was conjugated to the surface reactive amino groups (SRAG) of Cal-BSA-NP by sodium periodate oxidization, which resulted in calcein-loaded bovine serum albumin nanoparticles with their surface modified by glycyrrhizin (Cal-BSA-NP-GL). The morphology of the two types of prepared nanoparticles (NP) was observed by transmission electron microscopy. The diameter of NP was measured with a laser particle size analyzer. The interaction between Cal-BSA-NP-GL and primary cultured hepatocytes was studied through cellular uptake experiments. The uptake amount of Cal-BSA-NPGL and Cal-BSA-NP by rat hepatocytes was determinedby fluorospectrophotometry. Uptake characteristics were investigated through experiments of competitive inhibition of specific binding site of GL. RESULTS: Both Cal-BSA-NP-GL and Cal-BSA-NP had regular spherical surfaces. The average diameter of CalBSA-NP-GL and Cal-BSA-NP was 77 and 79 nm respectively. The uptake amount of the two NP by hepatocytes reached its maximum at 2 h after incubation. The uptake amount of Cal-BSA-NP-GL by rat hepatocytes was 4.43-fold higher than that of Cal-BSA-NP. There was a significant difference in the uptake of Cal-BSA-NP-GL and Cal-BSA-NP by hepatocytes (P＜0.01). The uptake of Cal-BSA-NP-GL was inhibited when GL was added previously to isolated rat hepatocytes, and the uptake of Cal-BSA-NP was not affected by GL.CONCLUSION: A binding site of GL is present on the surface of rat hepatocytes, BSA-NP-GL may be internalized via this site by hepatocytes and can be used as a drug carrier for active targeting of delivery drugs to hepatocytes.

Experimental study of therapeutic efficacy of Baicalin in rats with severe acute pancreatitis

AIM： To observe the therapeutic efficacy of Baicalin in rats with severe acute pancreatitis （SAP） and explore its therapeutic mechanisms. METHODS： The SAP rat models were randomly divided into the model control group, Baicalin treatment group, octreotide treatment group and sham operation group. All groups were randomly subdivided into 3 h, 6 h and 12 h groups with 15 rats in each group. The survival, ascites volume and pathological changes of pancreas in all rats were observed at different time points after operation. The plasma amylase content and serum TNF-α, IL-6, malonaldehyde （MDA） and PLA2 contents were also determined. RESULTS： The survival was not obviously different between the treated groups, and was significantly higher in treated groups at 12 h compared to the model control group （P 〈 0.05, 15 vs 10）. The ascites/body weight ratio at 3 h and 6 h was significantly lower in Baicalin treatment group compared to the model control group and octreotide treatment group （P 〈 0.05, 1.00 vs 2.02 and 1.43 and P 〈 0.001, 2.29 （1.21） vs 2.70 （0.80） and 2.08 （2.21）, respectively）. The contents of amylase, TNF-α, IL-6, MDA and PLA2 were significantly lower in the treated groups than in the model control group （P 〈 0.05, 4342 vs 5303, 5058 vs 6272 in amylase, P 〈 0.01, 21.90 vs 36.30, 23.80 vs 39.70, 36 vs 54.35 in MDA and 56.25 vs 76.10 in PIA2, or P 〈 0.001, 65.10 and 47.60 vs 92.15 in TNF-α, 3.03 vs 5.44, 2.88 vs 6.82, 2.83 vs 5.36 in IL-6, respectively）. The pathological scores of pancreas in the treated groups were significantly lower than that in the model control group （P 〈 0.05, 9.00 vs 10.05, 6.00 vs 9.00, 8.00 vs 10.05）, but no marked difference was found between the treated groups. CONCLUSION： The Baicalin injection has significant therapeutic effects on SAP rats, its effects are similar to those of octreotide. The Baicalin injection is also cheap and has a big application range, quite hopefully to be used in clinical treatment of SAP.

Studies on BN rats model to determine the potential allergenicity of proteins from genetically modified foods

AIM： To develop a Brown Norway （BN） rat model to determine the potential allergenicity of novel proteins in genetically modified food. METHODS： The allergenicity of different proteins were compared, including ovalbumin （OVA）, a potent respiratory and food allergen, bovine serum albumin （BSA）, a protein that is considered to have a lesser allergenic potential, and potato acid phosphatase （PAP）, a non-allergenic protein when administered to BN rats via different routes of exposure （intraperitoneally or by gavage）. IgG and IgE antibody responses were determined by ELISA and PEA, respectively. An immunoassay kit was used to determine the plasma histamine level. In addition, possible systemic effect of allergens was investigated by monitoring blood pressure. RESULTS： OVA provoked very vigorous protein-specific IgG and IgE responses, low grade protein-specific IgG and IgE responses were elicited by BSA, while by neither route did PAP elicit anything. In either routes of exposure, plasma histamine level in BN rats sensitized with OVA was higher than that of BSA or PAP. In addition, an oral challenge with BSA and PAP did not induce any effect on blood pressure, while a temporary drop in systolic blood pressure in few animals of each routes of exposure was found by an oral challenge with OVA. CONCLUSION： BN rat model might be a useful and predictive animal model to study the potential allergenicity of novel food proteins.

Effect of ZVAD-fmk on hepatocyte apoptosis after bile duct ligation in rat

AIM: Retention and accumulation of toxic hydrophobic bile salts within hepatocyte may cause hepatocyte toxicity by inducing apoptosis. Apoptosis is a pathway of cell death orchestrated by a family of proteases called caspases. Z-ValAla-Asp (OMe)-fluoromethyl ketone (ZVAD-fmk) is a cellpermeable irreversible inhibitor of caspase. The purpose of this study was to evaluate the possible effect of ZVAD-fmk on hepatocyte apoptosis after bile duct ligation in the rat.METHODS: Male Sprague-Dawley rats, weighing 250-300 g,were randomized to five groups of five rats each. Group 1 underwent common bile duct ligation and simultaneous treatment with ZVAD-fmk (dissolved in dimethylsulfoxide (DMSO)). Group 2 underwent common bile duct ligation and simultaneous treatment with Z-Phe-Ala-fluoromethyl ketone ( ZFA-fmk, dissolved in DMSO). Group 3 underwent sham operation and simultaneous treatment with the same amount of DMSO. Group 4 underwent sham operation and simultaneous treatment with the same amount of normal saline. Group 5 underwent common bile duct ligation without other manipulation. After three days, liver tissue was harvested for histopathologic analysis and measurements of apoptosis.RESULTS: When compared with sham operation, common bile duct ligation significantly increased hepatocyte apoptosis (P= 0.008) and ductular proliferation (P= 0.007).ZVAD-fmk significantly diminished the increased hepatocyte apoptosis and ductular proliferation after common bile duct ligation (P = 0.008 and P = 0.007, respectively). ZFA did not show the same effects.CONCLUSION: Hepatocyte apoptosis and ductular proliferation significantly increased after common bile duct ligation. ZVAD-fmk effectively diminished the increased hepatocyte apoptosis and ductular proliferation after common bile duct ligation, whereas ZFA-fmk did not.

谈实验动物小白鼠的饲养与管理

受到多方面因素影响,我国实验室小白鼠饲养过程中极易出现各种疾病,该点既不利于提升实验人员研究效率,也不利于我国科学业发展。因此为解决该点问题,本文开展实验动物小白鼠的饲养与管理研究,针对实验室小白鼠饲养中常见的疾病及其预防与治疗措施展开探讨,以期可以为我国科学业发展奠定良好基础。

Expression of tissue inhibitor of matrix metalloproteinases-1 during aging in rat liver

AIM: To investigate the expression and role of tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) during natural aging in rat liver and to detect the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9. METHODS: The rats were divided into 3-mo-old group (n=5), 10-mo-old group (n=5) and 24-mo-old group (n=5). Histopathologic changes of liver were observed with HE and Masson stain. The location and protein expressions of TIMP-1 were determined by immunohistochemistry and Western blot; message RNA (mRNA) levels were measured in livers from rats of various ages by semi-quantitative reverse transcriptional polymerase chain reaction (RT PCR). In addition, the expression of MMP-2 and MMP-9 was assessed by RT-PCR and Western blot. RESULTS: Histologic examination showed that the aging liver had excessive fatty degeneration and collagen deposition. Immunohistochemical staining showed that TIMP-1 related antigen in livers was located in cytoplasm. The protein expression of TTMP-1 was significantly higher in the oldest animals and the mRNA expression was increased significantly in the 24-mo-old rats (t= 4.61, P= 0.002<0.05, 24-vs 10-mo-old rats; t=4.31, P=0.003<0.05, 24- vs 3-mo-old rats). The expression of MMP-2 and MMP-9 had no change during aging; the ratios TIMP-1/MMP-2 and TIMP-1/MMP-9 in aging liver were significantly higher than those in maturation and young livers. CONCLUSION: TIMP-1 may play an important role in the process of liver aging.

Effect of the ulcerogenic agents ethanol, acetylsalicylic acid and taurocholate on actin cytoskeleton and cell motility in cultured rat gastric mucosal cells

AIM: To assess the effects of ulcerogenic agents on actin cytoskeleton and cell motility and the contribution of oxidative stress.METHODS: Rat gastric mucosal cell monolayers were cultured on coverslips. The cells were exposed, with or without allopurinol (2 mmol/L), for 15 min to ethanol (10-150 mL/L), ASA (1-20 mmol/L) or taurocholate (1-20 mmol/L), then the cells were processed for actin and vinculin staining. Cell migration after wounding was also measured.RESULTS: Exposure to 10 mL/L ethanol caused divergence of zonula adherens-associated actin bundles of adjacent cells and decreased rate of migration. These actions were opposed by xanthine oxidase inhibitor allopurinol. Exposure to 50 mL/L ethanol induced degradation and divergence of zonula adherens-associated vinculin from adjacent cells,which was, again, partially reverted by allopurinol. With 1 mmol/L ASA actin filaments became shorter and thicker.However, higher concentrations (10, 20 mmol/L) of ASA returned microfilaments thinner and longer, and decreased rate of migration. Zonula adherens-associated actin bundles were moderately distorted with 10 mmol/L ASA and with 10 mmol/L taurocholate. Exposure to taurocholate provoked changes resembling those of ASA. Taurocholate 5-20 mmol/L decreased the rate of migration dose dependently. The effects of ASA and taurocholate were not prevented by allopurinol.CONCLUSION: All ulcerogenic agents decreased the rate of migration dose dependently and induced divergence of zonula adherens-associated actin bundles of adjacent cells.In addition, ethanol and ASA caused degradation of actin cytoskeleton. Oxidative stress seems to underlie ethanol,but not ASA or taurocholate, induced cytoskeletal damage.

Avidin chase reduces side effects of radioimmunotherapy in nude mice bearing human colon carcinoma

AIM: To evaluate the influence of avidin chase on the side effects of radioimmunotherapy (RIT) in nude mice bearing human colon carcinoma and therapeutic outcome.METHODS: Purified anti-CEA monoclonal antibody (McAb)was biotinylated with NHS-biotin, and then radiolabeled with 188Re by the direct method. 188Re-labeledbiotinylated anti-CEA McAb (188Re-CEA McAb-Bt) was intravenously injected followed by intravenous injection of avidin after 24 h. SPECT imaging and biodistribution study were performed at 28-48 h after the injection of 188Re-CEA McAb-Bt. Three groups of nude mice subcutaneously grafted with human colon carcinoma were treated 7 d after the graft. Mice in the avidin chase group received intravenous injection of 188Re-CEA McAb-Bt (11.1 MBq/20 μg) followed by intravenous injection of cold avidin (80 μg) after 24 h. Mice in the control group (treated group without avidin chase) only received the injection of 188Re-CEA McAb-Bt (11.1 MBq/20 μg), another control group (non-treated group) only received 0.1 mL normal saline solution. Toxicity was evaluated on the basis of change of body weight and peripheral WBC counts, and therapy effects were determined by variation in tumor volume. Histological analysis of tumors was also performed.RESULTS: Avidin chase markedly accelerated the clearance of 188Re-CEA McAb-Bt from the blood and normal tissues. The tumor uptakes of 188Re-CEA Mc Ab-Bt at 28 h were 5.90 and 6.42% ID/g, respectively, in chase group and in non-chase group, while the tumor-to-background (T/NT) ratios were 3.19 and 0.56, respectively. The tumor uptake was slightly decreased by avidin chase, but the T/NT ratios were increased. In treated groups the growth rate of body weight and the number of WBC decreased after injection of 188Re-CEA McAb-Bt, and the WBC counts recovered earlier in the group with avidin chase than in the group without avidin chase. Compared to the nontreated group, treated groups with and without avidin chase showed significant anti-tumor effects.CONCLUSION: Avidin chase can effectively reduce the side effects of RIT, and improve therapeutic efficacy.