The effect of 1,3-diaminopropane on the urinary excretion of spermidine in the mouse

In the present investigation an increased urinary excretion of spermidine was observed in mice after the injection of 1,3-diaminopropane. The increase was mainly restricted to the unconjugated fraction of urinary spermidine and appeared not to be due to an increased biosynthesis of the amine.     

多胺在异丙肾上腺素所致大鼠心肌肥厚中的作用及意义

目的： 研究多胺、鸟氨酸脱羧酶(ODC)及精脒/精胺乙酰基转移酶（SSAT）在异丙肾上腺素所致大鼠心肌肥厚中的作用及机制。方法: 异丙肾上腺素（ISO）皮下注射复制大鼠心肌肥厚模型,应用反向高效液相色谱（RP-HPLC）、RT-PCR和Western blotting结合图像分析系统,分别检测ISO作用不同时点大鼠心肌组织多胺含量、ODC和SSAT mRNA和蛋白的表达。结果: 与对照组比较,心脏重量参数在ISO注射后7 d时显著增加,ISO注射后1 d时腐胺含量增加（P<0.05）,5 d、7 d时显著增加（P<0.01）;精脒含量在ISO注射后3 d时开始增加,ISO注射后7 d时增加显著（P<0.01）,精胺含量略有增多（P<0.05）,总多胺池显著增加。心肌组织ODC和SSAT的 mRNA表达在ISO注射后1 d时升高(P<0.05或P<0.01）,并持续在较高水平。心肌组织ODC和SSAT的蛋白表达分别在ISO注射后1 d和ISO注射后5 d时升高,ISO注射后7 d时显著升高（P<0.01）。结论: 大鼠心肌组织多胺含量增加和ODC、SSAT的表达增强可能参与ISO所致心肌肥厚的病理过程。     

Identification of the polyamine N 8-acetyltransferase involved in the pathway of 1,3-diaminopropane production in Acanthamoeba culbertsoni

 A cytosolic polyamine N-acetyltransferase that preferentially catalyzes the acetylation of spermidine in the N ⁸-position was identified in the free-living pathogenic amoeba Acanthamoeba culbertsoni. In addition to spermidine, the enzyme also catalyzed the acetylation of spermine and putrescine with Michaelis constants (K _m values) of 97, 12, and 10 μM, respectively. The K _m value for acetylcoenzyme A (acetyl-CoA) was estimated to be 11 μM, whereas CoA had an inhibitory constant of 6 μM. The N-acetylase has a molecular mass of approximately 45 kDa. That the enzyme preferentially catalyzed the acetylation of spermidine at the N ⁸-position, resulting in N ⁸-acetylspermidine, the preferred substrate of the polyamine oxidase found in A. culbertsoni, indicates a role for the enzyme in the production of 1,3-diaminopropane, the major polyamine found in the Acanthamoeba. Received: 20 June 1995 / Accepted: 16 September 1995     

Polyamines and nucleic acids in the mouse kidney induced to growth by testosterone propionate

Daily injections of testosterone propionate to castrated mice resulted in a striking increase in kidney weight. Renal putrescine rose sharply and the amounts of spermidine were also increased. The activity or ornithine decarboxylase was enhanced to values of more than 1 000 times the control level within a few days of testosterone substitution. A moderate and temporary increase in the activity of the putrescine-activated S-adenosyl-L-methionine decarboxylase was observed. Testosterone injections produced a large increase of renal RNA but only a minor change in DNA. It is apparent that in mice distinct alterations in polyamine metabolism occur during the development of renal hypertrophy induced by testosterone administration.     

Surgically induced hypertrophy in skeletal muscles of the laboratory mouse

Two surgical techniques were used to increase the work load per fiber in mouse skeletal muscles. These were, part removal of the muscle and incapacitation of a synergetic muscle. Both techniques were used for the soleus muscle. They resulted in the fiber size distribution of this muscle, which was normally unimodal, becoming distinctly bimodal. The same effect was obtained for the part removal of the anterior tibialis muscle. For the above mentioned muscles the extent of hypertrophy was very considerable. The recorded increase in the mean fiber cross-sectional area was in the region of 56% to 92%. Part removal of the biceps brachii however produced only a comparatively slight increase in fiber size (9%). In this case the normal muscle was bimodal and the effect of part removal was to slightly increase the size of the second peak. The reason for the two peaks occurring in the distributions of fiber size in some muscles was due to the presence of fibers at a basic level of development and also the presence of hypertrophied fibers. The increase in mean fiber size resulting from an increased work load was in all cases, due to a proportion of the basic fibers undergoing hypertrophy and not due to a gradual increase in the size of all the fibers.     

P38 MAPK信号通路在漆树酸改善苯肾上腺素诱导的小鼠心肌细胞肥大中的作用

目的:探讨P38丝裂原活化蛋白激酶(P38 mitogen-activated protein kinase, P38 MAPK)信号通路在漆树酸改善苯肾上腺素(phenylephrine, PE)诱导的小鼠心肌细胞肥大中的作用。方法:原代培养新生小鼠心肌细胞,PE诱导心肌细胞肥大。按随机数字表法将细胞分为空白对照组、溶剂对照组、PE组、PE+漆树酸组、PE+漆树酸+P38抑制剂组和PE+P38抑制剂组。收集干预48 h后的乳鼠心肌细胞进行以下检测:Western blot检测p-P38、第9位赖氨酸乙酰化的组蛋白H3(acetylated histone H3 at lysine 9, H3K9ac)和心房钠尿肽(atrial natriuretic peptide, ANP)的蛋白表达水平,免疫共沉淀(co-immunoprecipitation, Co-IP)法验证p-P38与H3K9ac蛋白之间的相互作用,RT-qPCR检测肌细胞增强因子2C(myocyte enhancer factor 2C, MEF2C)mRNA表达水平,免疫荧光染色观察小鼠心肌细胞表面积。结果:West...     

锌转运体8与小鼠睾丸间质细胞睾酮生成相关

目的锌转运体8(ZnT8)与胰岛素等激素的分泌有关,但其在睾丸的功能尚不清楚,本实验旨在探讨ZnT8在小鼠睾丸的分布与功能。方法通过免疫组织化学技术检测成年雄性小鼠睾丸ZnT8的分布;乳鼠腹腔注射hCG(human chorionic gonadotrophin,人绒毛膜促性腺激素),注射5d后,检测乳鼠睾丸ZnT8的分布;化学发光法检测乳鼠血清睾酮水平。结果 ZNT8主要分布在成年雄鼠睾丸间质细胞,hCG处理乳鼠在血清睾酮升高的同时伴有睾丸间质细胞ZnT8表达增加。结论 ZnT8的功能可能与小鼠睾丸间质细胞睾酮合成有关。     

Sirt1参与异丙肾上腺素诱导的小鼠心肌肥大

目的:观察Ⅲ类组蛋白去乙酰基酶1(Sirt1)在异丙肾上腺素(ISO)诱导的小鼠心肌肥大中的表达及作用。方法:昆明小鼠随机分为正常对照组、ISO模型组和ISO+NAM(烟酰胺,Sirt1抑制剂)组。皮下注射ISO诱导小鼠心肌肥大。以心脏重量指数(心脏重量/体重)、HE染色、透射电镜以及脑钠肽(BNP)mRNA表达水平观察心肌肥大的变化。同时采用RT-PCR、Western blotting检测各组心肌Sirt1 mRNA、蛋白质的表达。结果:与对照组相比,心脏重量指数,HE染色,透射电镜以及BNP mRNA表达水平均显示皮下注射ISO可明显诱导小鼠心肌肥大;Sirt1在心肌肥大模型组表达显著增多(P0.01),其抑制剂NAM可明显减轻ISO诱导的心肌肥大(P0.05),并降低Sirt1的表达(P0.01)。结论:Sirt1的激活可能参与ISO诱导的小鼠心肌肥大。     

Carcinogen induced unscheduled DNA synthesis in mouse hepatocytes

Mouse primary liver cell cultures were examined for evidence of unscheduled DNA synthesis (UDS) following treatment with the carcinogens; dimethylnitrosamine (DMNA), diethylnitrosamine (DENA), 2-acetylaminofluorene (2-AAF), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), benzo(a)pyrene (BP), dimethylbenzanthracene (DMBA), 1,1,-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), safrole, diethylstilbestrol (DES), aflatoxin B1 (AFB1), and dieldrin and the noncarcinogens; dimethylformamide (DMF), fluorene, and pyrene. Mouse hepatocyte cultures were simultaneously treated with three concentrations of each compound and 3H-thymidine. After 24 hrs, cells were fixed and processed for autoradiography. 3H-thymidine incorporation in both experimental and control cell nuclei, as evidenced by autoradiographic grains, was quantitated microscopically. DMNA, DENA, 2-AAF, MNNG, BP, AFB1 and DMBA significantly increased UDS over untreated cells at all concentrations studied. DDT, DMF, fluorene, pyrene, safrole, DES, and dieldrin were negative for UDS in all concentrations examined. DMNA, 2-AAF and MNNG were also studied for UDS induction in 2 hr old, 1 day old and 4 day old cultures. A progressive decrease in UDS with increased time after plating was found in DMNA and 2-AAF treated cultures. After 4 days DMNA and 2-AAF induced UDS only at the highest concentrations examined (10(-3) M and 10(-4) M respectively). MNNG induced UDS at all time periods and concentrations sampled. An attempt to enhance the sensitivity of the UDS assay by inducing the mixed function oxidative enzyme activity in the hepatocytes with phenobarbital administered in vivo resulted in no statistically significant increase in UDS with DMNA, 2-AAF, MNNG, DDT, and dieldrin when compared with cells from non-induced animals.     

DEHP对雄性仔鼠胚胎Leydig细胞雄激素合成的影响

目的:研究邻苯二甲酸二乙基己基酯(DEHP)对雄性仔鼠胚胎Leydig细胞(FLC)雄激素合成的影响。方法:DEHP分别以低、中、高3组剂量(10、100、750 mg.kg-1.d-1)灌胃作用于怀孕12 d到产后1 d(GD12-PND1)的SD母鼠,观察DEHP对雄仔鼠血清睾酮(T)水平、睾丸FLC形态结构、睾丸FLC的类固醇激素合成急性调节蛋白(StAR)及胰岛素样生长因子1(IGF-I)mRNA的相对表达量(ΔΔCT法)。结果:低剂量组血清T水平显著高于对照组(P0.01);而中、高剂量组血清T水平显著低于对照组(P0.05)。光镜下低剂量组可见间质细胞聚集呈簇分布,中剂量组与高剂量组均可见间质细胞呈瘤样增生。电镜示低剂量组间质细胞椭圆形、长梭形,脂质颗粒减少,线粒体、滑面内质网丰富。中、高剂量组间质细胞呈梭形或椭圆形,大小不一,核大、圆,胞浆丰富,细胞聚集一起,胞质内可见丰富的脂质颗粒,脂质颗粒染色深,滑面内质网及线粒体扩张。高剂量组睾丸FLC的StAR mRNA的相对含量显著低于对照组(P0.01)。低剂量组睾丸FLC的IGF-Ⅰ mRNA相对含量显著高于对照组(P0.01)。结论:DEHP对新生雄性仔鼠睾丸FLC有毒性作用,可影响雄性仔鼠睾丸FLC的形态学及其生成类固醇的能力。其可能机制是低剂量DEHP宫内暴露后,促进睾丸FLC的IGF-ⅠmRNA表达从而引起血清睾酮升高,而高剂量DEHP可能通过抑制睾丸FLC StAR mRNA表达从而降低血清睾酮水平。     

Electron microscopic radioautographic study on nucleic acid synthesis in perinatal mouse kidney tissue

The kidney tissues of ddY mice from fetal to postnatal day 14 were labeledin vitro with either³H-thymidine or³H-uridine and analyzed by light and electron microscopic radioautography. The labeling index (L.I.) with³H-thymidine or grain-number-per-cell with³H-uridine was calculated by light microscopic radioautography. The L. I. of glomeruli and uriniferous tubules in the metanephric cortex were high throughout the embryonic stages, and decreased rapidly after birth. Many³H-thymidine labeled immature cells were observed in the embryonic stages by electron microscopic radioautography. The grain-number-per-cell of glomeruli and uriniferous tubules labeled with³H-uridine decreased gradually from fetal to postnatal stages.     

Surface-associated motility, a common trait of clinical isolates of Acinetobacter baumannii, depends on 1,3-diaminopropane

While flagella-independent motility has long been described in representatives of the genus Acinetobacter, the mechanism of motility remains ambiguous. Acinetobacter baumannii, a nosocomial pathogen appearing increasingly multidrug-resistant, may profit from motility during infection or while persisting in the hospital environment. However, data on the frequency of motility skills among clinical A. baumannii isolates is scarce. We have screened a collection of 83 clinical A. baumannii isolates of different origin and found that, with the exception of one isolate, all were motile on wet surfaces albeit to varying degrees and exhibiting differing morphologies. Screening a collection of transposon mutants of strain ATCC 17978 for motility defects, we identified 2 akinetic mutants carrying transposon insertions in the dat and ddc gene, respectively. These neighbouring genes contribute to synthesis of 1,3-diaminopropane (DAP), a polyamine ubiquitously produced in Acinetobacter. Supplementing semi-solid media with DAP cured the motility defect of both mutants. HPLC analyses confirmed that DAP synthesis was abolished in ddc and dat mutants of different A. baumannii isolates and was re-established after genetic complementation. Both, the dat and ddc mutant of ATCC 17978 were attenuated in the Galleria mellonella caterpillar infection model. Taken together, surface-associated motility is a common trait of clinical A. baumannii isolates that requires DAP and may play a role in its virulence.     

Megsin基因转染对糖尿病小鼠肾脏炎症反应的影响及其机制研究

目的观察megsin基因转染对糖尿病小鼠肾组织单核细胞趋化蛋白-1(MCP-1)及细胞间黏附分子-1(ICAM-1)表达的影响,探讨megsin在糖尿病肾病发病机制中的作用。方法制备糖尿病小鼠模型,成模后随机选取10只作为糖尿病组(B组),剩余30只每周1次经尾静脉分别注射空质粒(C组),megsin表达质粒(D组),并设立正常对照组(A组)。实验共4周,于第4周末收集各组小鼠肾组织标本,分别应用Western blot和免疫组织化学染色测定肾组织中megsin、MCP-1、ICAM-1的表达;应用电镜观察肾小球超微结构的改变。结果糖尿病小鼠肾组织megsin、MCP-1及ICAM-1表达增强,基底膜普遍增厚,系膜区基质增多,上皮细胞足突融合;megsin基因转染后上述变化趋势更加显著。结论 megsin可上调MCP-1及ICAM-1表达,促进系膜细胞增殖及系膜外基质积聚,是加速肾小球硬化的可能机制之一。     

Effects of age at castration on testosterone induced aggression-promoting cues in groups of male mice

Groups of five male albino mice were set up in observation cages so that each contained one individual from each of the following five categories: trained fighters (T.F.); mice castrated pre-pubertally and implanted with testosterone in adulthood (P.I.); mice castrated pre-pubertally but sham-implanted in adulthood (P.S.); mice castrated in adulthood and implanted (A.I.) and mice castrated in adulthood but sham-implanted (A.S.). T.F's. became dominant to all these mice but did not distribute their attacks uniformly among the four categories of opponent. A.I. mice were attacked significantly more than P.I. mice which in turn were attacked significantly more than either P.S. or A.S. mice. It was concluded that the age at castration affected the response of mice to testosterone in terms of the production of aggression-eliciting olfactory cues. This effect seems likely to be a consequence of the duration of time between castration and hormonal treatment rather than an effect of age per se.     

睾酮对大鼠心肌梗塞后心肌肥大的影响

本文应用立体形态定量技术,观察睾酮(T)对心肌梗塞后心肌肥大的影响。实验分为:假手术组(S组)、心肌梗塞组(MI组)。心肌梗塞后睾酮治疗组(MIT组)。结果证明,与S组相比,MI及MIT组大鼠心肌细胞核密度明显减少,尤其以MIT组变化显著,MIT组平均核长度明显增加;MI组的 dp/dt max明显降低,T值延长,MIT组的上两指标无显著差异。MI后血浆T总浓度与平均每核心肌细胞体积呈显著正相关关系。提示:睾酮确实促进了MI后心肌肥大,从而促进了心功能的恢复。     

葛根总黄酮对离体神经肽Y诱导的心肌细胞肥大的影响

目的:观察葛根总黄酮对离体神经肽Y(NPY)诱导的心肌细胞肥大效应的影响。方法:建立体外培养的大鼠心肌细胞培养体系,实验分(1)对照组、(2)NPY组:加入终浓度为100 nmol/L的NPY、(3)NPY+葛根总黄酮4个浓度组:分别加入100 nmol/L NPY和0.5 mg/L、1 mg/L、2 mg/L、3 mg/L的葛根总黄酮。应用氚-亮氨酸([³H-Leu])掺入法测定心肌细胞蛋白合成率;RT-PCR法测心肌细胞C-jun mRNA表达;组织化学法测心肌钙调磷酸酶(CaN)活性。结果: NPY组心肌细胞[³H-Leu]掺入量为896±34;C-jun mRNA表达为23 132.62±1 787.28;CaN活性为35.62±4.60,与对照组(分别为[³H-Leu]752±46、C-jun mRNA 17 819.49±1 452.06、Can22.94±6.20)相比有显著差异(P＜0.01、P＜0.05)。而葛根总黄酮1-3 mg/L可使在NPY作用下的心肌细胞[³H-Leu]掺入量下降(3个剂量组分别为797±78、772±58、786±43);C-jun mRNA表达减少(分别为18 035.32±1 592.23、18 043.90±1 726.19、18 072.29±1 692.34);CaN活性降低(分别为28.34±6.40、25.69±5.90、26.37±3.50)与对照组相比无显著差异(P＞0.05)。结论:NPY可诱导心肌细胞肥大;葛根总黄酮在1-3 mg/L浓度可阻断其效应,其作用可能与抑制CaN活性、阻断Ca²⁺/CaM依赖的CaN信号途径有关。