氟对干热地区居民血清Fe、Zn、Ca和Mg含量的影响

本文对吐鲁大地区２个水氟含量不同〔其含量分别为０．９１ｍｇ／Ｌ（Ａ村）和０．５８ｍｇ／Ｌ（Ｂ村）〕的居民村维吾尔族居民饮水量、摄氟量、尿氟和血清Ｆｅ、ｚｎ、Ｃａ和Ｍｇ含量以及氟斑牙患病率进行了分析。结果显示，居民夏季饮水量明显升高（５～８Ｌ／ｄ），饮水摄氟量增多。尿氟含量增加，并出现氟中毒患者。氟斑牙患病率Ａ村为６５．５７％；Ｂ村为４８．９３％。通过对两村居民血清Ｆｅ、Ｚｎ、Ｃａ和Ｍｇ含量分析，发现血清Ｚｎ和Ｍｇ含量，两村居民无明显差异（Ｐ＞０．０５），说明短期（夏季）过量摄氟对Ｚｎ和Ｍｇ代谢的影响不大，但血清Ｆｅ和Ｃａ差别显著，Ａ村居民血清Ｆｅ含量明显升高，血清Ｃａ含量明显降低。表明氟对血清Ｆｅ和Ｃａ的代谢有明显影响。由此可见，氟对机体的损伤不仅表现为直接损伤，还可通过影响体内无机元素的代谢造成损伤。     

硒对氟致雄性大鼠生殖损害的拮抗作用

目的 :探讨硒对高氟所致雄性大鼠生殖损害的拮抗作用。方法 :1 0 0只雄性Wistar大鼠随机分成对照组、氟 (NaF 1 5 0mg/L)组、氟加低硒 (0 .5mg/L亚硒酸钠 )组、氟 (NaF 1 5 0mg/L)加中硒 (2 .0mg/L亚硒酸钠 )组、氟(NaF 1 5 0mg/L)加高硒 (4 .0mg/L亚硒酸钠 )组 5组 ,通过饮水加氟、加硒的方法染毒 1 0周。观察氟、硒对大鼠体重、睾丸和附睾质量及其脏器系数 ,精子计数、活动率及畸形率 ,睾丸、附睾生化标志酶 ,血清性激素 ,睾丸组织病理切片以及初级精母细胞染色体畸形率的影响。结果 :①右侧睾丸质量对照组为 (1 .80± 0 .2 2 )g ,氟加高硒组为 (1 .6 1±0 .1 1 )g ,2者相比差异有统计学意义 (P <0 .0 5 )。②精子计数 :氟组 (9.2 3× 1 0 7ml-1 )、氟加中硒组 (37.6 7× 1 0 7ml-1 )与对照组 (2 8.6 0× 1 0 7ml-1 )比较 ,差异有统计学意义 (P <0 .0 0 1 ) ;精子畸形率 :氟组 (36 .33% )氟加中硒组 (1 2 .70 % )与对照组 (1 4 .83% )比较 ,差异有统计学意义 (P <0 .0 0 1 ) ;精子活动率 :氟组 (6 2 .0 7%± 6 .5 0 % )氟加中硒组 (6 8.2 1 %± 4 .99% )与对照组 (73.6 7%± 6 .5 1 % )比较 ,差异有统计学意义 (P <0 .0 0 1 )。③LDH :氟组 ((5 79.4 7± 97.1 6 )u/g)、氟加中硒组 ((72 6 .1 3± 1 1     

福州市温泉型地方性氟中毒病区原生环境的探讨

福州市区温泉型地方性氟中毒病区呈点状分布,范围局限,明显不同于我国北方氟中毒病区片状的分布。本文从水文地质方面分析我省温泉型氟中毒点状病区的成因,为改换水源降低水氟含量的预防措施提供科学依据。     

Cardiac metabolism: A technical spectrum of modalities including positron emission tomography,single-photon emission computed tomography,and magnetic resonance spectroscopy

Noninvasive techniques for the assessment of cardiac metabolism are important for the detection of potentially salvageable tissue in jeopardized areas of the myocardium. The correct identification of hibernating and stunned myocardium in patients with severely depressed cardiac function can have vital therapeutic consequences for the patient. Changes in myocardial fatty acid and glucose metabolism during acute and prolonged ischemia can be traced by positron-emitting or gamma-emitting radiopharmaceuticals. Alternatively,³¹P-labeled magnetic resonance spectroscopy can be used for the assessment of high-energy phosphate metabolism. It is not yet clear which modality will emerge as the most useful in the clinical setting. Positron emission tomography (PET) that uses combinations of flow tracers and metabolic tracers offers unique opportunities for quantification and high-resolution static and rapid dynamic studies. Currently, assessment of glucose metabolism with¹⁸F-fluorodeoxyglucose is regarded as the gold standard for myocardial viability and prediction of improvement of impaired contractile function after revascularization. However, preserved oxidative metabolism may be required for potential functional improvement, and therefore assessment of residual oxidative metabolism by¹¹C-labeled acetate PET may prove to be more accurate than¹⁸F-fluorodeoxyglucose PET, which reflects both anaerobic and oxidative metabolism. Moreover, because fatty acids are metabolized only aerobically, they are excellent candidates for the clinical assessment of myocardial viability and prediction of functional improvement after revascularization. Especially derivatives of fatty acids that are not metabolized but accumulate in the myocyte are attractive for myocardial imaging. Examples are¹²³I-beta-methyl-p-iodophenyl pentadecanoic acid and 15-(o-¹²³I-phenyl)-pentadecanoic acid. These tracers can be detected by planar scintigraphy and single-photon emission computed tomography, which are more economical and widely available than PET. In addition, 511 keV collimators have been developed recently, making the detection of positron emitters by planar scintigraphy and single-photon emission computed tomography feasible. The experience with³¹P-labeled magnetic resonance spectroscopy in humans is still limited. With current magnetic resonance spectroscopic techniques, insufficient spatial resolution is achieved for clinical purposes, but the possibility of serial measurements to monitor rapid changes of phosphate-containing molecules in time makes magnetic resonance spectroscopy very valuable for the research of myocardial metabolism.     

Limitations of radioactive microspheres as tracers for bone blood flow and extraction ratio studies

Summary Radioactive microspheres have been used for measuring bone blood flow and the extraction ratios of bone-seeking radionuclides, but we have shown that the technique is not completely valid. Bone uptake of¹⁸F and⁸⁵Sr was compared with that of microspheres simultaneously injected into the heart or aorta of rats and rabbits under a variety of conditions. In single-passage experiments with quick killing to avoid recirculation, attention was focused on the tibiae and femora which could be dissected quickly to avoid post-mortem migration. For the rest of the skeleton, the effect of the latter was minimized by allowing recirculation for 5 min and comparing blood flow determinations in conjunction with a cardiac output measurement. The apparent extraction ratio of¹⁸F was variable and always exceeded unity in the single-passage experiments. With recirculation, there were significant differences between the extraction ratios for some bones, and the ratios sometimes exceeded unity. Extraction ratios for⁸⁵Sr were similarly variable, but lower. When⁸⁵Sr was compared directly with¹⁸F, the relative extraction ratio was 0.8, with little variation between bones or animals. It is concluded that the flux of microspheres entering the vasculature of bone is not representative of blood flow, owing to the removal of some microspheres in pre-osseous capillary beds. Microspheres are therefore not a satisfactory standard for the determination of extraction ratios.     

Reblurred deconvolution method for chemical shift removal in F-19 (PFOB) MR imaging.

Perfluorocarbons such as perfluoroctylbromide (PFOB) can be used as contrast agents in the vascular system for fluorine-19 magnetic resonance imaging or as synthetic oxygen carriers. F-19 imaging has been proposed for studying the vascular system, capillary flow, tissue perfusion, and tumor oxygenation. A major difficulty is that F-19 compounds often have complex multipeak spectra. These peaks result in chemical shift artifacts, lower signal-to-noise ratios, and blurred images. Each peak also excites a different section when a section-select gradient is applied. Direct inverse filtering is the simplest deconvolution method for correcting such artifacts; however, two major difficulties present themselves: functional singularity and noise amplification at high frequencies. The use of a new reblurred deconvolution (RED) method appears to overcome these problems. Although this method is based on iterative deconvolution in the spatial domain, the computational overhead is negligible. Since the point spread function and object data are already available in the time domain as FID data, RED appears to be useful for eliminating chemical shift artifacts and suppressing noise amplification while restoring the original image without loss of resolution.     

氟对小鼠子代生长发育的影响

观察结果显示，染氟各组仔鼠机体组织氟含量增高，大脑皮质神经细胞超微结构异常。０．４５ｍｇ／ｋｇ剂量组仔鼠已表现为体格和早期神经行为发育迟缓；而０．４５ｍｇ／ｋｇ剂量组３０日龄仔鼠血清溶血素水平显著增高。表明氟可经母体对仔鼠各系统的发育产生不同影响。     

Synthesis of 2‐[(4‐[18F]Fluorobenzoyloxy)methyl]‐1,4‐naphthalenedione from 2‐hydroxymethyl 1,4‐naphthoquinone and 4‐[18F]fluorobenzoic acid using dicyclohexyl carbodiimide

2‐[(4‐[¹⁸F]Fluorobenzoyloxy)methyl]‐1,4‐naphthalenedione ([¹⁸F]7 ) and 4‐[¹⁸F]fluorobenzoic acid ([¹⁸F]8 . This coupling reaction was fast and gave quantitative yields. Further investigations are warranted on the use of DCC as a coupling agent in Positron Emission Tomography. The synthesis including HPLC purification and reformulation has been fully automated on a modified FDG synthesiser with two reactor vials. [¹⁸F]1 was found to be stable in plasma and saline, but underwent rapid metabolism in a phase 1 metabolite assay using rat S9 liver fractions. An in vivo evaluation of [¹⁸F]相似文献   

Transferred NOESY NMR studies of biotin mimetic peptide (FSHPQNT) bound to streptavidin: a structural model for studies of peptide-protein interactions

Protein–protein interactions control signaling, specific adhesion, and many other biological functions. The three‐dimensional structures of the interfaces and bound ligand can be approached with transferred nuclear Overhauser effect spectroscopy NMR, which can be applied to much larger proteins than conventional NMR and requires less concentrated protein. However, it is not clear how accurately the structures of protein‐bound peptides can be determined by transferred nuclear Overhauser effect spectroscopy. We studied the structure of a biotin mimetic peptide (FSHPQNT) bound to streptavidin, because the X‐ray structure of the complex is available to 1.74 Å resolution, and we found that conditions could be adjusted so that the off‐rates were fast enough for transferred nuclear Overhauser effect spectroscopy NMR. The off‐rate was determined with ¹⁹F NMR, using a para‐fluoro‐phenylalanine analog of the peptide. A new criterion for a lower limit on kinetic off‐rate was found, which allowed accurate structure determination at a slower off‐rate. Non‐specific binding of the peptide to streptavidin was not significant, because biotin blocked the peptide transferred nuclear Overhauser effect spectroscopy. Protein mediation for the long‐range peptide transferred nuclear Overhauser effect spectroscopy cross‐peaks was corrected by a transferred nuclear Overhauser effect spectroscopy/ROESY averaging procedure. The protein‐bound structure of the peptide was determined by transferred nuclear Overhauser effect spectroscopy constrained and simulated annealing. The structure deduced from the NMR was close to the X‐ray structure.