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21.
In vivo Intracellular Recording of Neurons in the Supraoptic Nucleus of the Rat Hypothalamus 总被引:3,自引:0,他引:3
R. E. J. Dyball J-G. Tasker J-P. Wuarin F. E. Dudek 《Journal of neuroendocrinology》1991,3(4):383-386
Intracellular recordings were made from cells in the hypothalamic supraoptic nucleus in the urethane-anaesthetized male rat using the ventral surgical approach. Impalements lasted from 5 min to 1 h and recorded cells had an input resistance of 55 to 170 megohms. Spikes of over 50 mV were recorded from 14 cells which could be antidromically activated by stimulation of the neural stalk. The spikes showed a hyperpolarizing afterpotential and the broadening characteristic of rapidly firing magnocellular neurons, which recovered rapidly (<200 ms). When depolarized, the cells showed evidence of a transient potassium current. Recurrent synaptic coupling between the recorded cell and adjacent cells would be expected to alter the hyperpolarizing afterpotential of an antidromic spike as compared with a spontaneous spike; no perceptible difference in the waveforms of the different types of spike could be detected in 11 spontaneously active cells. Application of just subthreshold stimuli to the neural stalk did not evoke depolarizing or hyperpolarizing potentials. Suprathreshold shocks to the neural stalk, when the antidromic spike was prevented by collision, also had no discernible effect on membrane potential. Thus intracellular recordings from magnocellular neurons in vivo revealed electrophysiological properties similar to those seen in vitro. No evidence for synaptic interconnection between magnocellular neurons was found in male rats. 相似文献
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E. Drakaki E. Borisova M. Makropoulou L. Avramov A. A. Serafetinides I. Angelov 《Skin research and technology》2007,13(4):350-359
BACKGROUND/PURPOSE: Laser-induced autofluorescence spectroscopy provides excellent possibilities for medical diagnostics of different tissue pathologies including cancer. However, to create the whole picture of pathological changes, investigators collect spectral information from patients in vivo or they study different tumor models to obtain objective information for fluorescent properties of every kind of healthy and diseased tissue. Therefore, it is very important to find the most appropriate, and close to the human skin, animal samples from the fluorescence point of view, which will allow the extrapolation of the animal data to human spectroscopic diagnostics. METHODS: In the present work, we examined the autofluorescence properties of different animal skin tissues, which are considered as the most common skin models. A nitrogen laser was used as an excitation source. Samples of healthy mouse, chicken and pig skin in vivo and/or ex vivo were studied and were compared with results obtained from investigations of healthy human skin in vivo. RESULTS AND CONCLUSION: Specific features of the recorded spectra are discussed and the possible origin of the obtained fluorescence signals is proposed. Quantitative evaluation of data extrapolation for each skin type is also depicted. 相似文献
24.
Teng-Yi Huang Hsiao-Wen Chung Fu-Nien Wang Cheng-Wen Ko Cheng-Yu Chen 《Magnetic resonance in medicine》2004,51(2):243-247
In this work the feasibility of separating fat and water signals using the balanced steady-state free precession (SSFP) technique is demonstrated. The technique is based on the observation (Scheffler and Hennig, Magnetic Resonance in Medicine 2003;49:395-397) that at the nominal values of TE = TR/2 in SSFP imaging, phase coherence can be achieved at essentially only two orientations (0 degrees and 180 degrees ) relative to the RF pulses in the rotating frame, under the assumption of TR < T2, and independently of the SSFP angle. This property allows in-phase and out-of-phase SSFP images to be obtained by proper choices of the center frequency offset, and thus allows the Dixon subtraction method to be utilized for effective fat-water separation. The TR and frequency offset for optimal fat-water separation are derived from theories. Experimental results from healthy subjects, using a 3.0 Tesla system, show that nearly complete fat suppression can be accomplished. 相似文献
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目的研究原癌基因c-myc和jun在人胎冠状动脉发育过程中的表达与平滑肌细胞增殖的关系.方法用原位杂交方法检测,胎龄分别为16周、22周(因治疗需要引产)的胎儿和意外死亡的足月胎儿冠状动脉前降支c-myc mRNA和jun mRNA的表达水平.杂交反应产物用图像分析仪(MIAS300)作定量分析.结果C-myc mRNA原位杂交反应产物与被测血管区域面积的百分比在16周、22周和足月胎儿分别是70、56和10;Jun mRNA的杂交信反应产物与被测血管区域面积的百分比在这三个时期分别是68、53和8.两个原癌基因在不同阶段的表达均具有显著性差异.结论本实验首次报道c-myc和jun在人胎冠状动脉发育过程中平滑肌的表达图型,c-myc和jun在胎儿冠状动脉平滑肌细胞增殖和内膜的形成过程中可能具有重要的调控作用. 相似文献
27.
辛伐他汀对人低密度脂蛋白氧化修饰影响的实验研究 总被引:2,自引:2,他引:0
目的研究辛伐他汀在体外对低密度脂蛋白氧化修饰的影响.方法以低密度脂蛋白氧化修饰为模型,以硫代巴比妥酸反应物质(TBARS)生成量及相对电泳迁移率(REM)为指标,研究了辛伐他汀对铜离子(Cu2 )诱导低密度脂蛋白氧化修饰的抑制作用.结果随辛伐他汀浓度从1~10μmol/L的增加,TBARS值分别减少67.3%,73.9%,81.9%,REM值减少48.3%,55.2%,58.6%,呈浓度及时间依赖关系.其中10μmol/L辛伐他汀可几乎完全抑制低密度脂蛋白氧化.结论辛伐他汀在体外能明显抑制Cu2 诱导的低密度脂蛋白氧化修饰. 相似文献
28.
Eugenia Cordelli Anna Maria Fresegna Alessia D'Alessio Patrizia Eleuteri Marcello Spanò Francesca Pacchierotti Paola Villani 《Toxicological sciences》2007,99(2):545-552
The increasing request of chemical safety assessment demands for the validation of alternative methods to reduce the resort to animal experimentation. Methods that evaluate reproductive toxicity are among those requiring the largest use of animals. Presently, no validated in vitro alternative exists for the assessment of reproductive toxicity. Mammalian sperm are sensitive targets of DNA-reactive chemicals, which form premutagenic adducts. Here, we propose a new method based on comet assay to detect DNA damage induced by potential germ cell mutagens in bull sperm available from assisted reproduction practices. In somatic cells, chemical-induced adducts can be revealed by comet assay that detects DNA breaks produced during adduct repair. Mature sperm, however, are devoid of repair enzymes, and adducts are processed only after fertilization. For this reason, comet assay is not sensitive to detect DNA lesions induced in sperm by most chemicals. To overcome such limitation, we developed a modified comet assay based on the addition of a protein extract from HeLa cells to agarose-embedded sperm on microscopic slides. To test the method, sperm were treated in vitro with methyl methanesulfonate (MMS) or melphalan (MLP) and comet assay was conducted both with and without protein supplementation. No effect of MMS or MLP was detected without protein supplementation; on the contrary, a clear-cut dose-dependent effect was measured after addition of the cell extract. These results represent a proof of concept of a novel in vitro mutagenicity test on sperm that could offer a promising approach to complement previously validated in vivo germ cell genotoxicity assays. 相似文献
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30.
Holger F. Boehm Felix Eckstein Caecilia Wunderer Volker Kuhn Eva-Maria Lochmueller Karin Schreiber Dirk Mueller Ernst J. Rummeny Thomas M. Link 《Journal of clinical densitometry》2005,8(4):488-494
We tested the hypothesis that bone mineral density (BMD) and bone mineral content (BMC) in proximal human femur specimens in the upper neck region of interest (ROI) and femoral neck axis length (FNAL) provide a significantly better prediction of femoral bone strength than standard ROIs in vitro. BMD and BMC were measured in 110 proximal femur specimens using a standard dual-energy X-ray absorptiometry (DXA) scanner. The analysis included a new ROI in the upper neck as well as the standard ROIs. FNAL was obtained from the scan images. The specimens' failure-load was measured in a mechanical loading device, simulating a fall on the greater trochanter. For the standard ROIs, correlations between failure-load and BMD ranged from R2 = 0.64 (shaft ROI) to R2 = 0.70, p < 0.001 (femoral neck). Prediction of strength by BMD did not significantly differ from those of BMC (R2 ranging from 0.65 to 0.75, p < 0.001). In the upper neck ROI, for both BMD and BMC correlations with failure-load were higher (R2 = 0.76 and 0.81, respectively; p < 0.001). A lower, yet still significant, correlation was found between FNAL and bone strength (R2 = 0.23, p < 0.001). Normalization of failure-load with respect to FNAL did not significantly increase the correlations with densitometric measures. This study provides in vitro evidence indicating that among the ROIs of the proximal femur the newly defined upper neck ROI provides the best prediction of bone strength. Only a weak association was observed between failure load and FNAL. 相似文献