Cadmium modification of nucleolar function and structure in Physarum polycephalum

Exposure of Physarum to CdSO₄, 1.5 × 10^?3m for 2–3 hr in early S phase (the onset of DNA synthesis and nucleolar reconstruction) resulted in the appearance of ring-shaped nucleoli. We have investigated the effects of cadmium on nucleolar (ribosomal) RNA synthesis during this interval with acrylamide-agarose gel electrophoresis. Cadmium significantly depressed [³H]uridine incorporation into rRNA, with the extent of inhibition increasing with time. The effect of cadmium on RNA synthesis was quantitative, not qualitative: Cadmium depressed the amplitude of individual RNA peaks but not their distribution in RNA profiles. Cadmium exposure did not result in the appearance of new (or altered) rRNA peaks, induce detectable degradation/turnover of RNA, or alter rRNA processing. Surprisingly, no significant difference in rRNA content and distribution was observed in cells treated with cadmium which induced rings and shorter exposures which did not, suggesting that the inhibition of rRNA synthesis and the formation of ring-shaped nucleoli are coincident manifestations of cadmium toxicity at the cellular level but are not causally related.     

Effects of citrinin on renal function and structure

Citrinin is a nephrotoxic mycotoxin produced by Penicillia and Aspergilli. This study defines, functionally and histopathologically, the effects of citrinin on the rat kidney. Rats were anesthetized, prepared surgically, and then infused with [³H] inulin and p-aminohippurate (PAH) in saline prior to and during renal function and clearance studies. One group of rats served as the control and animals in this group were not treated with citrinin. Rats in 2 additional groups received either 5 or 50 mg/kg [¹⁴C] citrinin (i.v.) and were used immediately for clearance experiments. Four days after pretreatment with 50 mg/kg citrinin (i.p.), rats in a fourth group which showed signs of acute renal failure were given an additional 5 mg/kg [¹⁴C] citrinin (i.v.). Control rats developed saline diuresis, reaches a peak urine volume of 1.94 ml/20 min at 80 min, and cleared inulin and PAH at 2.4 and 7.45 ml/min, respectively. Non-pretreated rats receiving 5 and 50 mg/kg [¹⁴C] citrinin at time zero cleared inulin at 2.26 and 1.65 ml/min, respectively, and cleared PAH at 4.02 and 3.88 ml/min, respectively. “Nephrotoxic” rats did not develop saline diuresis. “Nephrotoxic” rats also cleared inulin and PAH at rate significantly lower than controls: 0.25 and 0.2 ml/min for inulin and PAH, respectively. The PAH/inulin clearance ratio was significantly lower in all treatment groups than in controls. Na⁺ excretion followed a pattern similar to urine excretion for each group, however, the rate of K⁺ excretion was significantly lower in all treatment groups than in the control group. The fractional K⁺ reabsorption in non-pretreated rats receiving 5 (63%) and 50 (83%) mg/kg [¹⁴C] citrinin was increased significantly over controls (46%). Filtered K⁺ reabsorbed by “nephrotoxic” rats was a negative 35%, i.e. K⁺ secretion occurred. Clearance of [¹⁴C] citrinin in non-pretreated rats receiving 5 and 50 mg/kg was 6.8 and 4.1 ml/min, respectively. Rats which exhibited nephrotoxicity (“nephrotoxic rats”) cleared the labelled citrinin at a rate of 1.25 ml/min. Histopathological changes observed in kidneys of rats treated with 50 mg/kg citrinin (i.p.) could be classed as reversibly or irreversibly injured by citrinin. Rats which excreted a high urine volume and excess protein and glucose on day 3 or 4 after treatment showed irreversible cellular injury, primarily located in the proximal convoluted tubules.     

Effects of prenatal nitrofen exposure on cardiac structure and function in the rat

The herbicide nitrofen was administered to pregnant Fischer-344 and Sprague-Dawley rats on Days 10-13 of gestation (po, 20 or 40 mg/kg daily) and its effects on cardiac structure and function were investigated in the offspring. In the 21-day fetuses, nitrofen did not influence intrauterine growth or basal heart rate. In contrast, the herbicide produced a marked depression of heart rate and abnormal electrocardiographic (ECG) profiles in the newborn rats, in conjunction with labored respiratory movements and a profound increase in postnatal mortality. A few animals displayed cardiac ventricular septal defects and diaphragmatic hernias but these malformations did not appear to be associated with the ECG changes. The chronotropic deficiencies seen in the nitrofen-treated pups were reversible by acute hyperoxia (40% oxygen). These results suggest that the teratogenic effects of nitrofen on cardiac physiology and on postnatal mortality cannot be accounted for solely by specific gross anatomical damages to the rat heart and diaphragm; rather, other more subtle morphological and physiological factors which contribute to improper systemic delivery and cellular utilization of oxygen may be involved.     

Effects of dialkoxylphenyl compounds with oxime group on macrophage function and the proliferation of lymphocytes

Dialkoxyphenyl compounds have been reported to possess anti-inflammatory activity through inhibition of phosphodieseterase (PDE) type IV. In this study, a series of derivatives of dialkoxyphenyl compounds with an oxime group, which is generally known to be one of the biologically active functional groups, were prepared and evaluated for their ability to inhibit the production of inflammatory mediators in activated macrophages and the proliferation of lymphocytes. The structure-activity relationship (SAR) study with 12 compounds on tumour necrosis factor (TNF)-alpha inhibition, analysed by the oxime geometry and different size of spacers between the oxime and phenyl group, indicated that there might be at least three possible hydrogen bonding sites in the inhibitor binding pocket of PDE IV. Of them, compound 6 clearly displayed the highest inhibitory effect on in-vitro TNF-alpha production from lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Compound 6 also suppressed in-vivo TNF-alpha release from LPS-primed mice, a level comparable with that of the standard PDE IV inhibitor, rolipram. In addition, oxime compounds also significantly inhibited both nitric oxide production from activated RAW264.7 cells and T lymphocyte proliferation elicited by concanavalin A but not IL-2. The data suggest that the oxime group may act as a functional group, capable of interacting with the inhibitor-binding pocket of target PDE IV. Therefore, it is conceivable that compound 6 may have the potential either to be developed as a new anti-inflammatory drug or to be used to develop more potent analogues.     

雷帕霉素对小鼠T淋巴细胞的体外作用

目的 研究雷帕霉素对小鼠T淋巴细胞体外的增殖、白细胞介素2(IL-2)表达及细胞周期的影响.方法 将C57BL/6小鼠脾脏制备成脾单个核细胞,使用免疫磁珠法分选出小鼠T淋巴细胞.T细胞分别加入0、10、20、30和40 ng/ml梯度浓度的雷帕霉素培养液培养72 h后,采用MTT法及ELISA法测定各组细胞的增殖情况及IL-2表达情况;用流式细胞仪测定40 ng/ml雷帕霉素浓度组及对照组(0 ng/ml)细胞周期的变化情况.结果 用雷帕霉素培养液培养细胞时,细胞增殖及IL-2的表达均受到抑制(P＜0.01).随药物浓度增加,细胞增殖及IL-2表达受抑制越明显(P＜0.01);细胞周期分析显示加入雷帕霉素培养的T淋巴细胞与未使用药物刺激者相比,G0G1期细胞的比例升高(P＜0.01),S期降低(P＜0.01).结论 在体外雷帕霉素对小鼠T细胞的增殖、IL-2的表达起抑制作用,且随浓度增加,抑制作用增强;雷帕霉素将小鼠T细胞抑制在G0G1期.     

缬沙坦对自发性高血压大鼠血管结构和舒缩功能的影响

目的观察缬沙坦对自发性高血压大鼠(SHR)的血压、血管功能和结构的影响.方法30只12 wk龄雄性SHR,随机分成3组,每组10只缬沙坦大剂量组(30 mg*kg-1*d-1);缬沙坦小剂量组(10 mg*kg-1*d-1); SHR模型对照组,另设同龄雄性正常血压WKY大鼠作为正常对照组(n=10).用无创法测定尾动脉收缩压及心率,至给药 4 wk 处死.测定胸主动脉、肠系膜动脉分支第三级血管壁(中膜)/腔面积比,并采用平衡记录仪记录离体的动脉环对血管活性药物去甲肾上腺素(NE)和硝普钠反应的敏感性.结果与模型组相比,大、小剂量缬沙坦均能降低SHR血压,肠系膜动脉壁肥厚明显改善(P＜0.01);大剂量明显减少主动脉腔壁比(P＜0.01),小剂量缬沙坦也可减少腔壁比,但无统计学意义;大、小剂量均能使胸主动脉及肠系膜动脉对硝普钠的舒张敏感性增加 (P<0.05),对NE收缩的敏感性降低(P<0.05).结论缬沙坦能改善SHR的非内皮依赖性血管舒张功能,使SHR血管对循环〗活性物质的异常反应改善,并抑制SHR的血管壁变厚.     

Effects of carbon tetrachloride on adrenocortical structure and function in guinea pigs

The influences of in vivo treatment with two pure PCB congeners, 2,2',4,4',5,5'-hexachlorobiphenyl (HCBP) and 3,3',4,4'-tetrachlorobiphenyl (TCBP), on the lethal cytotoxicity of bromobenzene and acetaminophen were examined in short-term primary cultures of isolated rat hepatocytes. Lethal injury was measured by release of lactate dehydrogenase (LDH) into culture medium after 20 hr exposure to the hepatotoxins. The HCBP, a PB-type inducer of cytochrome P-450, resembled phenobarbitone (PB) in its ability to increase susceptibility of hepatocytes to bromobenzene (0.5 to 1.6 mM) and acetaminophen (1 to 16 mM). This induced sensitivity was consistently inhibited by SKF-525-A (10 microM) but not alpha-naphthoflavone (ANF, 10 microM) in culture. The 3,3',4,4'-TCPB, a 3-MC-type inducer of cytochrome P-450, resembled 3-methylcholanthrene (3-MC) in its inability to induce susceptibility to bromobenzene. TCBP and 3-MC each increased (20- to 30-fold) cytotoxicity of acetaminophen by a mechanism substantially inhibitable by ANF but not SKF-525-A. These results demonstrate that categorizing pure PCB isomers and congeners into groups according to their different induction capabilities is predictive for their ability to modulate acute hepatocellular necrosis by bromobenzene and acetaminophen.     

Effects of mercury bichloride on mouse kidney polyribosome structure and function

Polyribosome sedimentation pattern and their in vitro protein synthetic ability were investigated in kidneys of mice treated with a single injection of HgCl₂. Mercury bichloride, after 1 h, evokes polyribosome disaggregation, the extent of which is logarithmically correlated with the dose in the range of 2.5–20 moles/kg. With the dose of 2.5 moles/kg the effect occurs after 1 h, it is maximal between 1 h and 3 h. After 6 h polyribosomes are reaggregated. Cyclohehimide pretreatment does not prevent the HgCl₂ induced disaggregation of kidney polyribosomes. The cell-free system derived from kidneys of HgCl₂ treated mice (10 moles/kg, 1 h) has a decreased protein synthetic ability. Both, in livers of mice treated with 20 moles/kg HgCl₂ and in isolated rat's reticulocytes incubated with 20 M HgCl₂ during 1 h there were no apparent changes in the polyribosome sedimentation patterns.This work was supported by a grant from the Research Fund of SR Croatia and by a Wellcome Trust grant, and we are grateful to both these organisations     

Effects of lithium and neuroleptics and combinations of the two on renal function and structure in rats

The effects of 8 weeks of treatment with lithium and neuroleptics, alone and combined, on renal concentrating ability and morphology were studied in rats. LiCl was administered in the diet and neuroleptics were given as one daily dose: haloperidol 1 mg/kg, chlorpromazine 15 mg/kg, and perphenazine 4 mg/kg. Plasma lithium levels were about 1 mmol/l, and the area under the plasma concentration curve was not statistically different in the control and neuroleptic groups. Rats treated with lithium developed marked polyuria which was less in rats receiving neuroleptics concomitantly. After 8 weeks, rats treated with lithium alone showed marked impairment of renal concentrating ability and moderate degree of structural renal changes. Neuroleptics alone had no effect on concentrating ability or renal morphology, nor did they aggravate the changes caused by lithium. In fact, neuroleptics seemed to improve the concentrating ability in rats treated with lithium. It is concluded that in rats high doses of neuroleptics do not potentiate lithium-induced functional and structural renal changes.     

The effects of feed restriction during in utero and postnatal development in rats.

This study determined the effects of feed restriction (FR) during in utero and postnatal life on standard reproductive toxicity and developmental immunotoxicity end points. Groups of 26 time-mated CD rats were fed various amounts of Purina 5002 diet from gestation day 7 through lactation. Control rats were fed once per day in amounts based on historical control feed consumption data, while the amounts fed to the FR groups were reduced by 10% (10% FR), 30% (30% FR), or 50% (50% FR) relative to controls. Selected F1 weanlings were necropsied on postnatal day (PND) 22, assessed for immunotoxicity end points between PND 22 and 27 or PND 52 and 56, or maintained on FR through PND 70. Thereafter, half the remaining F1 rats in each group were fed ad lib (recovery subgroup), while the rest continued on FR. Both subgroups were necropsied at 21 weeks of age. In the 10% FR group, slight decreases in maternal body weight had no effect on F1 offspring body weights, but did decrease F1 liver weights. FR at the 30% level reduced maternal body weights by 10-20%, reduced F1 offspring body weights by as much as 21%, caused changes in numerous weanling organ weights, but did not affect reproductive or immune system function. Dams in the 50% FR group were 17-32% lighter than controls, resulting in F1 body weights that were 12-47% lower than controls. F1 estrous cycle length was increased, puberty was delayed by 6 days (males and females), and anogenital distance, epididymal sperm counts, and all organ weights were decreased in this group. Antibody responses were unaffected despite decreased spleen and thymus weights. Essentially all effects of feed restriction showed evidence of reversibility.     

氟伐他汀对自发性高血压大鼠阻力血管结构和功能的影响(英文)

目的:探讨氟伐他汀(HMG-CoA还原酶抑制剂)对自发性高血压大鼠阻力血管结构和功能的影响。方法:8周龄雄性SHR大鼠,氟伐他汀20mg·kg~(-1)·d~(-1)灌胃治疗。计算血管壁腔比作为阻力血管结构变化指标;应用离体主动脉和肠系膜动脉环对硝普钠和去甲肾上腺素反应的敏感性,观察治疗后血管的功能变化。结果:8周后,治疗组血管的壁腔比低于对照的SHR(0.44±0.09 vs 0.79±0.09,P<0.05);氟伐他汀能增加SHR主动脉对硝普钠舒张的敏感性,EC_(50)[(4.9 vs 190)pmol·L(-1)P<0.05];减弱主动脉和肠系膜动脉对去甲肾上腺素收缩的敏感性,EC_(50)[主动脉:(0.20 vs 0.02)nmol·L~(-1),P<0.05;肠系膜动脉:(1.46 vs 0.72)nmol·L~(-1),P<0.05]。结论:短期氟伐他汀治疗,改善SHR大鼠阻力血管的舒缩功能,同时也抑制了SHR大鼠在血压发展过程中伴随的血管壁肥厚现象。     

丙酸睾酮对大肠杆菌RecQ解旋酶结构和功能的影响

目的研究体外丙酸睾酮对大肠杆菌RecQ解旋酶结构和功能的影响及二者的相互作用机制。方法分别运用荧光偏振技术、ATPase试剂盒和紫外吸收光谱技术分析丙酸睾酮对大肠杆菌RecQ解旋酶活性和DNA结合活性、AT-Pase活性和构象的影响。结果丙酸睾酮能够影响E.coliRecQ解旋酶的活性。低浓度促进解旋酶活性,高浓度抑制;抑制RecQ解旋酶与dsDNA的结合活性,其抑制常数Ki小于7×10-5 nmol.L-1;对与ssDNA结合活性的Ki为7×10-3 nmol.L-1;对ATPase活性抑制作用的时间相关性较弱;影响RecQ解旋酶的构象变化,但峰位无偏离。结论提示丙酸睾酮与RecQ解旋酶具有弱相互作用,二者具有两个结合位点。     

逍遥散对抑郁大鼠行为学及骨骼肌线粒体结构与功能的影响

目的 观察逍遥散对抑郁大鼠行为学及其骨骼肌线粒体超微结构和功能的影响。方法 将SD大鼠随机分为对照组、模型组、文拉法辛（给予盐酸文拉法辛胶囊35 mg·kg^-1）组和逍遥散（生药21.2 g·kg^-1）组,每组12只。除对照组外,采用孤养结合28 d慢性不可预知温和应激（CUMS）建立抑郁模型,造模同时给药,每天1次,连续给药28 d。对大鼠的体质量、糖水偏爱率及旷场实验中的直立次数、穿越格数进行评价;在透射电镜下观察骨骼肌线粒体结构,试剂盒法检测骨骼肌线粒体中腺嘌呤核苷三磷酸（ATP）和线粒体呼吸链复合体（MRCC）I、Ⅱ、III、IV、V水平。结果 与对照组比较,模型组大鼠体质量增长显著减缓、糖水偏爱率、直立次数和穿越格数显著减少（P＜0.05、0.01）;与模型组比较,文拉法辛组和逍遥散组造模第3、4周大鼠体质量显著增加（P＜0.05、0.01）,文拉法辛组造模第2、3周和逍遥散组造模第1～4周大鼠糖水偏爱率显著升高（P＜0.05、0.01）,文拉法辛组造模第1、3、4周和逍遥散组造模第3、4周大鼠直立次数显著增加（P＜0.05、0.01）,文拉法辛组造模第1～4周和逍遥散组造模第3、4周大鼠穿越格数显著增多（P＜0.05、0.01）。透射电镜结果发现,与对照组比较,模型组大鼠骨骼肌线粒体数目减少、空泡变性及形态肿胀;与模型组比较,文拉法辛组和逍遥散组的大鼠骨骼肌线粒体结构和功能损伤较轻。与对照组比较,模型组大鼠骨骼肌中的MRCC Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和ATP水平显著下降（P＜0.05、0.01）;与模型组比较,文拉法辛组MRCC Ⅰ、Ⅱ、Ⅳ水平,逍遥散组MRCC Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和ATP水平均显著升高（P＜0.05、0.01）。结论 抑郁大鼠出现骨骼肌线粒体结构和功能损伤,可能是引起抑郁大鼠产生疲劳的原因之一;逍遥散可通过保护骨骼肌线粒体结构和功能进而改善大鼠抑郁症状。     

Effects of PEG size on structure, function and stability of PEGylated BSA

The effects of PEGylation on the structural, thermal and functional stability of bovine serum albumin (BSA) were investigated using BSA and 6 linear mono-PEGylated BSA compounds. The secondary and tertiary structure of BSA measured by circular dichroism (CD) was independent of PEGylation. In contrast, the thermal stability of BSA was affected by PEGylation. The apparent unfolding temperature T_max measured by differential scanning calorimetry (DSC) decreased with PEGylation, whereas the temperature of aggregation, T_agg, measured by dynamic light scattering (DLS) increased with PEGylation. The unfolding temperature and the temperature of aggregation were both independent of the molecular weight of the PEG chain. Possible functional changes of BSA after PEGylation were measured by Isothermal Titration Calorimetry (ITC), where the binding of sodium dodecyl sulphate (SDS) to BSA and PEGylated BSA was analysed. At 25 °C, two distinct classes of binding sites (high affinity and low affinity) for BSA and one class of binding site (low affinity) for PEGylated BSA were identified. The binding isotherm was modelled assuming independence and thermodynamic equivalence of the sites within each class. From the present biophysical characterisation, it is concluded that after PEGylation BSA appears to be unaffected structurally (secondary and tertiary structure), slightly destabilised thermally (unfolding temperature), stabilised kinetically (temperature of aggregation) and has an altered functionality (binding profile). These biophysical characteristics are all independent of the molecular weight of the attached polymer chain.     

氟伐他汀对自发性高血压大鼠阻力血管 功能的影响

AIM: To evaluate the effects of fluvastatin, a hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitor, on the alterations of structure and function of resistant vessels in spontaneously hypertensive rats (SHR). METHODS: Eight-week-old male SHR were given fluvastatin 20 mg.kg-1.d-1 by gavage. Rats were decapitated at 16 wk. Wall-to-lumen area ratios (W/L) of thoracic aorta and mesenteric arteries (3rd grade branch) were assessed by morphometric assay. The effects of fluvastatin on vascular reactivity to sodium nitroprusside (SNP) and norepinephrine (NE), were studied with rings of thoracic aorta and mesenteric arteries isolated from rats. RESULTS: After 8 wk of treatment, histological examination showed that the wall-to-lumen area ratio was lower in SHRflu than that in SHR (0.44 +/- 0.09 vs 0.79 +/- 0.09, P < 0.05). EC50 of vasodilation response was much lower in SHRflu than that in SHR [(4.9 vs 190) pmol.L-1, P < 0.05], while EC50 of mesenteric artery rings from SHRflu was somewhat lower than that of SHR [(0.02 vs 0.04) nmol.L-1, P > 0.05]. In both aortic and mesenteric artery rings, EC50 of vasoconstriction in response to NE from SHRflu was higher than that of SHR [thoracic aorta: (0.20 vs 0.02) nmol.L-1, P < 0.05; mesentric arteries: (1.46 vs 0.72) nmol.L-1, P < 0.05]. CONCLUSION: Short-term treatment with fluvastatin ameliorated the vasomotoricity of resistant vessels, enhanced the sensitivity to vasodilator and depressed the sensitivity to vasoconstrictor; fluvastatin also attenuated the resistant vascular hypertrophy during the development of hypertension in SHR.     

葛根素对T淋巴细胞核仁区嗜银蛋白的影响

目的观察葛根素对外周血T淋巴细胞核仁区嗜银蛋白(Ag鄄NORs)的影响。方法采用KL型免疫图像分析系统检测T淋巴细胞Ag鄄NORs。结果使用葛根素前、后T淋巴细胞Ag鄄NORs分别为(5.67±0.95)%、(6.19±1.16%),二者相比,P<0.05,有显著差异,使用葛根素治疗后T淋巴细胞Ag鄄NORs含量增加。结论葛根素有增强机体细胞免疫功能的作用。     

T淋巴细胞核仁组成区相关蛋白检测在口腔颌面部肿瘤诊断中的意义

目的：观察口腔颌面部肿瘤患者术T淋巴细胞核仁组成区相关蛋白（Ag-NORs）的表达特点,以探讨其在口腔颌面部肿瘤诊断中的价值。方法：采用肿瘤免疫图像分析系统及配套试剂对正常人、口腔颌面部良、恶性肿瘤患者外周血T淋巴细胞Ag-NORs进行检测和分析。结果：正常人组与口腔颌面部良、恶性肿瘤组Ag-NORs值差异均有显著性（P＜0．01）;同时,良、恶性肿瘤组Ag-NORs值差异仍有显著性（P＜0．01）。结论：外周血T淋巴细胞Ag-NORs表达与口腔颌面部肿瘤呈良好的相关性;Ag-NORs的检测值可作为口腔颌面部肿瘤诊断的重要参考指标。     

深低温贮存对小鼠脾淋巴细胞功能的影响

本文报告应用低温生物学技术对小鼠脾淋巴细胞保存的研究。各种冻存方法中,以含10—15%DMSO 的冷冻保护液,以每分钟1℃降温速率从0℃降至-50℃,液氮(-196℃)储存效果最好,解冻复温后的脾淋巴细胞存活率>90%。连续观察冻存2个月以内的脾淋巴细胞其活性及功能无明显改变。