Method for the determination of the total fluorine content of whole blood,serum/plasma,and other biological samples

A procedure for the determination of total fluorine in whole blood, serum/plasma, and other biological samples is described. The method is based on oxygen bomb combustion reaction with triethylsilanol, and gas chromatography. By eliminating the combustion step, only ionic or acid-labile fluoride is measured. The difference between the two results gives the organic or “bound” fluoride level of the sample.     

氟对大鼠肝组织细胞凋亡与DNA损伤的影响

目的研究大鼠染氟后肝组织细胞凋亡及DNA损伤情况。方法 SD大鼠随机分为对照组、低氟组、中氟组、高氟组,每组12只,分别饮用含氟化钠为0、50、100、200 mg/L的去离子水,均饲标准营养大鼠饲料,染氟120 d。肉眼观察牙齿的变化,采用氟离子选择电极法测定大鼠尿氟,HE染色观察组织病理学变化,彗星实验检测细胞DNA损伤,流式细胞术检测肝脏组织细胞凋亡率。结果低氟组、中氟组、高氟组大鼠尿氟分别为（23.52±2.91）、（30.16±4.78）、（61.23±3.98）mg/L,均显著高于对照组（0.07±0.02）mg/L,差异有统计学意义（P〈0.01）。不同剂量染氟大鼠肝组织细胞呈现不同程度肿胀,肝组织内出现多种灶状病变。各染氟组大鼠肝细胞拖尾率及拖尾长度与相应的对照组相比,差异均有统计学意义,并且肝细胞拖尾率及拖尾长度随染氟剂量的加大而增大。不同剂量染氟组细胞凋亡率与对照组相比,均明显增高,而且高、中氟组肝细胞凋亡率显著高于低氟组（P〈0.01）。结论氟化物可导致大鼠肝细胞DNA损伤,诱导细胞凋亡,一定浓度的氟化物诱导大鼠肝细胞凋亡与DNA损伤之间存在着相关性。     

Distribution and forms of fluorine in whole blood of human male

Distribution and absolute concentration of three kinds of fluoride/fluorine, i.e., free ionic, ionizable, and organic fluorine, in human whole blood and serum were determined. The method is based on low temperature oxygen plasma ashing, acid hydrolysis, gas chromatography using chlorotrimethylsilane, and fluoride ion-specific electrode. A large part (40%) of the total F is distributed in clot of the whole blood and 74% of the total F is in the form of organic fluorine.     

氟化天然产物生物合成的研究进展

氟元素是一种具有特殊性质的卤素,含氟有机物可广泛应用于生物有机化学、药物化学和生物材料科学等领域。尽管C-F键的合成方法有所创新,但将氟元素掺入到结构复杂的生物活性分子中的方法较少,因此选择性的氟化仍极具挑战性。本文从自然界中氟化天然产物及氟化酶的发现、氟化天然产物的合成通路、氟化天然产物合成机制的意义、氟化酶的进化及氟化物的合成、氟化酶和氟化物的应用等方面进行综述,希望可以为氟化物的生物法合成领域提供信息参考,推进氟化物生物法合成的工业化进程。     

Micro-PIGE determination of fluorine distribution in developing hamster tooth germs

A micro-PIGE (Proton-Induced gamma-ray Emission) technique based on the delayed 5/2+----1/2+ nuclear transition of fluorine (E gamma = 197 keV, t1/2 = 87 ns) emitted after 19F(p,p', gamma)19F reaction was used to detect and study the distribution of fluorine in the developing enamel organ during pre-eruptive stages, i.e., the transitional to early maturation stages of enamel formation in neonatal hamsters administered a single IP dose of sodium fluoride (20 mg NaF/kg body weight). The aforementioned nuclear reaction is unique for fluorine, and therefore detection of gamma-rays emanating from this reaction in a biological specimen implies a positive identification of fluorine at that particular site. Calcium and phosphorus X-rays were also recorded and used as parameters for assessment of the relationship between the degree of mineralization and fluoride incorporation into the enamel organ. The highest fluorine concentration in the enamel organ was recorded in the dentin near the dentin-enamel junction (DEJ). In the enamel, the highest concentration of fluorine was found to be associated with the more mature areas of the enamel near the DEJ, but gradually decreased in the direction of the enamel surface. Fluorine was not detected in the control germs. These results suggest that administration of fluoride in high doses during the pre-eruptive stages of enamel formation leads to incorporation of the ion into the forming dentin and enamel mineral, and that the enamel matrix does not seem to bind fluoride avidly.     

氟的环境地球化学行为及其对生态环境的影响

近几十年来,氟的区域性环境地球化学异常和人为环境污染所导致的植物和人体氟暴露现象引起了广泛关注,世界各国学者对不同环境介质中氟的地球化学行为进行了较为深入的研究,但仍然存在诸多争议和不确定性.本文回顾了近些年来有关氟在大气、水、土壤中的来源、数量、存在形态、迁移转化和控制因素等方面的研究成果,以及氟的地球化学行为与植物和人体氟暴露的关联性,并提出了未来有关氟的环境地球化学行为研究应优先考虑的几个方向.     

Fluorine-substituted dihydrobicyclomycins: synthesis and biochemical and biological properties

Many studies show that selective introduction of fluorine within pharmacological agents leads to improved activities. In this study, we determine the effects of aryl fluorine substitution in 5a-(benzylsulfanyl)-dihydrobicyclomycin (3) on the in vitro inhibition of Escherichia coli rho-dependent ATPase activity. Compound 3 is an analog of bicyclomycin (1), which is the only known selective inhibitor of rho, and 1 and 3 have comparable in vitro inhibitory activities. We demonstrate that aryl fluorine substitution of 3 leads to increase in inhibitory activity but that the beneficial effects due to fluorine were dependent upon the site and number of fluorine substituents. The bioactivities are rationalized in terms of the bond moment created by the aryl fluoride bond within the 5a-aryl dihydrobicyclomycin-rho-binding pocket. Use of this hypothesis led to the design of dihydrobicyclomycin derivatives with superior in vitro rho inhibitory activities.     

Factors influencing the urinary fluoride level in subjects drinking fluoride-poor waters.

The influence on the urinary F level of the short-term consumption of drinking water of 1 mg/litre fluoride content, of the ingestion of low (1.0 to 2.0 mg) and higher (7.0 and 8.0 mg) fluoride doses and of tea has been studied. Excess fluoride is rapidly excreted with urine, and may disturb the results of urinary fluoride estimation. The urinary F level responds sensitively to the ingestion of fluorine.     

Fluorinated carbohydrates as potential plasma membrane modifiers and inhibitors. Synthesis of 2-acetamido-2,6-dideoxy-6-fluoro-D-galactose

Reaction of benzyl 2-acetamido-3,4-di-O-benzyl-2-deoxy-6-O-mesyl-alpha-D-galactopyran oside with cesium floride gave benzyl 2-acetamido-3,6-anhydro-4-O-benzyl-2-deoxy-alpha-D-galactopyranoside instead of the desired 6-fluoro derivative. Acetonation of benzyl 2-acetamido-2-deoxy-6-O-mesyl-alpha-D-galactopyranoside gave the corresponding 3,4-O-isopropylidene derivative. The 6-O-mesyl group was displaced by fluorine with cesium fluoride in boiling 1,2-ethanediol, and hydrolysis and subsequent N-acetylation gave the target compound. In another procedure, treatment of 2-acetamido-1,3,4-tri-O-acetyl-2-deoxy-alpha-D-galactose with N-(diethylamino)sulfur trifluoride gave 2-acetamido-1,3,4-tri-O-acetyl-2,6-dideoxy-6-fluoro-D-galactose which, on acid hydrolysis followed by N-acetylation, gave 2-acetamido-2,6-dideoxy-6-fluoro-D-galactose.     

土壤氟形态与氟污染土壤修复

我国土壤氟污染问题严峻,给部分地区人体健康和生态安全造成严重威胁,但土壤氟污染与防治问题仍没有受到人们的广泛关注.本文概述了土壤中氟的存在形态以及发生的主要化学反应,综述了近年来国内外有关氟污染土壤修复的研究进展,提出了今后氟污染土壤修复的研究方向,以期为氟污染土壤的修复提供借鉴和参考.土壤中氟主要分为5种形态,其中90%以上以残渣态存在,土壤溶液中的氟主要发生沉淀-溶解、络合-解离和吸附-解吸等反应来维持水-土系统中的氟平衡.目前,氟污染土壤修复技术研究主要集中在化学固定修复技术、化学淋洗技术、电动修复技术以及植物修复技术.今后需要重点研究氟在土壤中的赋存形态及其影响因子,筛选功能微生物和植物,开发联合修复技术以修复氟污染土壤.     

Dietary High Fluorine Induces Apoptosis and Alters Bcl-2, Bax, and Caspase-3 Protein Expression in the Cecal Tonsil Lymphocytes of Broilers

Long-term excessive fluoride intake is known to be toxic and can lead to fluorosis and bone pathologies. However, the cellular mechanisms underlying sodium fluoride-induced cytotoxicity in the cecal tonsil lymphocytes are not well understood. The aims of this study were to investigate the effects of high dietary fluorine on apoptosis and the expression of the Bcl-2, Bax, and caspase-3 in the cecal tonsil lymphocytes of broilers. The broilers were fed on high-fluorine diets containing 0, 400, 800, and 1,200 mg/kg fluorine. As measured by flow cytometry, the percentage of apoptotic lymphocytes was significantly increased in the high-fluorine groups II and III when compared with those in the control group. Meanwhile, immunohistochemical tests showed that the Bcl-2 protein expression decreased, and the Bax and caspase-3 protein expression increased in the high-fluorine groups II and III. In conclusion, dietary fluorine in the range of 800–1,200 mg/kg increased lymphocyte apoptosis in the cecal tonsil of broilers, suggesting that the lymphocyte apoptosis in the cecal tonsil was mediated by direct effects of fluoride on the expression of Bcl-2, Bax, and caspase-3.     

Effect of excessive dietary fluoride on nutrient digestibility and retention of iron, copper, zinc, and manganese in growing pigs

Ninety-six crossbred growing pigs were used to evaluate the effects of fluoride levels on growth performance, nutrient digestibility, and the retention of minerals in tissues. Four dietary treatments were formulated by supplementing fluorine (as NaF) to a corn-soybean basal diet (39.75 mg/kg F) to provide the following added fluorine levels: 0, 50 100, and 150 mg/kg fluorine. The results showed pigs of the 100 and 150 mg/kg fluorine-added groups had decreased average daily gain (ADG) and increased feed gain ratio (F/G) compared to the control (p<0.05). Apparent digestibility of protein and calcium in 100 and 150 mg/kg fluorinetreated groups was significantly lower than that of the control (p<0.05). On the other hand, iron, copper, zinc, and manganese levels in most tissues of the 100 and 150 mg/kg fluorine groups were markedly changed compared to the control (p<0.05). However, growth performance, nutrient digestibility, and mineral concentrations in all tissues of pigs were not significantly affected by the addition of 50 mg/kg fluorine (p>0.05). Thus, this study suggested that excess fluoride levels could decrease growth performance and change the retention of iron, copper, zinc, and manganese in pigs.     

Urethane protected amino acid N-carboxyanhydrides and fluorides (U-NCAs and U2AAFs)

Summary In order to obtain peptide analogues containing a central pyrrolide bond, as potential mechanism-based inhibitors of the HIV-1 proteinase, activated derivatives of amino acids were required. Treatment of a N,N-bis(Boc) amino acid pyridinium salt with cyanuric fluoride in dichloromethane furnished the correspondingbis(Boc) amino acid fluoride (Boc₂AAF). Use of the Vilsmeier reagent in acetonitrile, instead of the cyanuric fluoride, led to a N-Boc amino acid N-carboxyanhydride (Boc-NCA). From a mixed N-Z,N-Boc amino acid salt a N-Z,N-Boc amino acid fluoride and a Z-NCA were respectively obtained. The very sensitive Young test showed that during the coupling of the N-benzoyl-L-Leucine N-carboxyanhydride or the N-benzoyl N-Boc-L-leucyl fluoride with ethyl glycinate the degrees of racemization were weak. Owing to the electronegativity and the small size of the fluorine atom, thebis(urethane) amino acid fluorides are efficient acylating agents for amines and pyrrole anions.     

Fluorine compounds inhibit the conversion of active type-1 protein phosphatases into the ATPMg-dependent form.

1. The modulator protein slowly converts the glycogen-bound protein phosphatase from liver, as well as its catalytic subunit, into an inactive form that requires protein kinase FA and MgATP for reactivation. The inactivation process could be completely prevented by addition of either 0.3 mM-NaF or 0.3 mM-phenylmethanesulphonyl fluoride (PMSF). The effectiveness of the proteinase inhibitor was not due to production of free fluoride. With the catalytic subunit a half-maximal effect of either fluorine compound was obtained at 25-50 microM. 2. The inactivation process was instantaneously blocked by the addition of NaF or PMSF at any moment during the incubation of the catalytic subunit with modulator. This fluoride effect was reversible. It did not result from a decreased affinity of modulator for the catalytic subunit. The use of analogues of PMSF showed that the fluorine atom was essential, but structural aspects were also an important determinant. 3. The relative efficiency of fluorine compounds in preventing the inactivation of the catalytic subunit by modulator corresponded to their relative potency as inhibitors of the phosphorylase phosphatase activity, but the latter effect required at least 20-fold higher effector concentrations. Incubation of the catalytic subunit with 10 mM-PMSF or -NaF caused an irreversible inhibition of the enzyme. 4. It is possible to prepare stable complexes of catalytic subunit and modulator, either active or ATPMg-dependent. Both species displayed the same molecular size during gel filtration. The inactive complex could be reactivated by incubation with MgATP and protein kinase FA. NaF and PMSF increased the final extent of re-activation at limiting concentrations of the protein kinase.     

Synthesis and tissue distribution of fluorine-18 labeled trifluorohexadecanoic acids. Considerations in the development of metabolically blocked myocardial imaging agents

A versatile method for the synthesis of trifluoro fatty acids, potential metabolically blocked myocardial imaging agents, has been developed. Two trifluorohexadecanoic (palmitic) acids have been prepared [6,6,16-trifluorohexadecanoic acid (I) and 7,7,16-trifluorohexadecanoic acid (II)], each of which bears two of the fluorine atoms as a gem-difluoromethylene unit on the fatty acid chain (at C-6 or C-7) and the third at the omega (C-16) position. The metabolic stability of carbon-fluorine bonds suggests the gem-difluoro group may block the beta-oxidation pathway, while the terminal fluorine could be the site for labeling with fluorine-18. The convergent synthetic approach utilizes a 2-lithio-1,3-dithiane derived from 10-undecenal or 9-decenal, which is alkylated with the OBO (oxabicyclooctyl) ester of 5-bromopentanoic acid or 6-bromohexanoic acid, respectively. Hydroboration-oxidation and alcohol protection are followed by halofluorination to convert the 1,3-dithiane system to a gem-difluoro group. The third fluorine is introduced by fluoride ion displacement of a trifluoromethanesulfonate. This synthesis is adapted to the labeling of these trifluoro fatty acids with the short-lived radionuclide fluorine-18 (t1/2 = 110 min), with the third fluorine introduced as fluoride ion in the penultimate step. The radiochemical syntheses proceed in 3-34% radiochemical yield (decay corrected), with an overall synthesis and purification time of 90 min. Tissue distribution studies in rats were performed with I and II, as well as with 16-[18F]fluoropalmitic acid (III), [11C]palmitic acid, and [11C]octanoic acid. The heart uptake of the fluoropalmitic acids decreases with substitution, the 2-min activity level for 16-fluoropalmitic acid being 65% and that for both 6,6,16- and 7,7,17-trifluoropalmitic acids being 30% that of palmitic acid. Fluorine substitution results in some alteration in the retention of activity by the heart: 16-fluoropalmitate actually clears more rapidly than palmitate, but the two trifluoropalmitates (particularly 6,6,16-trifluoropalmitate, I) show somewhat slower clearance of activity, although the improvement of I over palmitate is only modest. There is considerable accumulation of activity in the bone after administration of the fluorine-18 labeled fatty acids, suggestive of metabolic defluorination. These results indicate that fluorine substitution alters the physicochemical properties of the fatty acid so that uptake by the myocardium is diminished. Furthermore, while the gem-difluoro substituents at C-6 and C-7 may block beta-oxidation, the chain-terminal radiofluorine substituent is subject to omega-oxidation that releases it as fluoride ion.     

家蚕耐氟性差异的细胞化学研究

对不同蚕品种的耐氟性、ACPase的氟敏感性、蚕品种耐氟性机理的研究表明,在供试蚕品种中以浙农1号的耐氟性最强,杭 8的耐氟性最弱;家蚕Bombyx mori血淋巴ACPase活性与蚕品种的耐氟性无明显关系;氟对蚕的血淋巴和中肠组织细胞的ACPase活性都有抑制作用,并随着氟添食浓度的增加ACPase活性降低,但超过一定浓度的氟添食,血淋巴ACPase活性反而有一个回升的过程,这个转折点出现可能的浓度及回升的幅度与蚕品种的耐氟性有关;细胞化学研究发现此转折点的出现是由于高浓度氟引起细胞结构的破坏而导致蚕体组织细胞内的ACPase大量向血腔释放的结果;氟敏感性蚕品种杭 8在很低氟量添食即可引起中肠组织细胞的ACPase大量向血腔释放,使血淋巴中的ACPase活性大幅度上升,随后ACPase活性受到完全的抑制;耐氟性较强的蚕品种浙农1号则在较高的氟含量添食时才向血腔释放ACPase,且血淋巴中ACPase增高的幅度小,在很高的氟量添食时全面抑制中肠ACPase活性。氟对不同品种ACPase活性影响的差异被认为是家蚕品种耐氟性差异机理之一。     

Possible Involvement of Toluene-2,3-Dioxygenase in Defluorination of 3-Fluoro-Substituted Benzenes by Toluene-Degrading Pseudomonas sp. Strain T-12

Pseudomonas sp. strain T-12 cells in which the toluene-degradative pathway enzymes have been induced can transform many 3-fluoro-substituted benzenes to the corresponding 2,3-catechols with simultaneous elimination of the fluorine substituent as inorganic fluoride. Substrates for this transformation included 3-fluorotoluene, 3-fluorotrifluorotoluene, 3-fluorohalobenzenes, 3-fluoroanisole, and 3-fluorobenzonitrile. While 3-fluorotoluene and 3-fluoroanisole produced only defluorinated catechols, other substrates generated catechol products with and without the fluorine substituent. The steric size of the C-1 substituent affected the ratio of defluorinated to fluorinated catechols formed from a substrate. A mechanism for the defluorination reaction involving toluene-2,3-dioxygenase is proposed.     

Reaction pathways for biodehalogenation of fluorinated anilines

Pathways for biodehalogenation of fluorinated aniline derivatives were investigated. Microsomal NADPH-dependent dehalogenation of fluoroanilines was shown to proceed by three different reaction pathways. The first route appeared to result in monooxygenation at a fluorinated position and release of the fluorine atom as a fluoride anion. The primary additional reaction product formed is the reactive quinoneimine, not the 4-hydroxyaniline. In NADPH-containing microsomal systems with 4-fluoro-substituted anilines, formation of the 4-hydroxyaniline derivative is observed because NADPH chemically reduces this quinoneimine metabolite. A second pathway for dehalogenation proceeds by protein binding of a fluoro-containing (semi)quinoneimine metabolite, the formation of which may result from the mono-oxygenase reaction (pathway 1) and/or from (re)oxidation of a hydroxyaniline metabolite by superoxide anion radicals produced by the microsomal system. This latter reaction pathway becomes more important with increasing number of fluoro-substituents in the fluoroaniline derivative. The higher ratio of fluoride anion formed to 4-hydroxyaniline derivative detected in incubations with liver microsomes from dexamethasone-treated rats, as compared to incubations with liver microsomes from control rats, can in part be explained by the higher production of superoxide anion radicals observed in the dexamethasone systems. The third mechanism was shown to proceed by formation of a hydroxylated metabolite that loses fluoride anion upon exposure to oxygen. The reactive intermediate formed upon oxygen exposure might be the semiquinoneimine which loses its fluorine atom as a fluoride anion upon dimerization or polymerization and/or protein binding. The fluorohydroxyanilines, in which the hydroxyl group is ortho or para with respect to the fluoro substituent, appear especially to be highly unstable and lose fluoride anion in the presence of oxygen. Finally, it is concluded that all three pathways for dehalogenation of fluorinated aniline derivatives are bioactivation pathways. The reactivity of the (semi)quinoneimines formed in these reactions is dependent on their substitution pattern and increases with increasing number of fluoro-substituents. Therefore, bioactivation for a series of fluorinated aniline derivatives, can be expected to vary with the substitution pattern and to increase with increasing number of halogen substituents.     

Effects of nitrogen on properties of oxyfluoronitride bioglasses

Bioglasses are used as bone substitutes and prosthetic coatings. Following implantation, they are predisposed to generate a series of physicochemical reactions at the glass-bone interface. Bioglasses with molar composition: 55SiO₂–8.5CaO–31.5Na₂O–5CaF₂ have been synthesized and characterized. However, because of their poor strength, doping with nitrogen was performed on these glasses to increase their mechanical properties. These glasses were chemically analyzed to verify the amount of nitrogen introduced and structurally characterized by ²⁹Si and ¹⁹F MAS NMR. The fluorine complexes with calcium and sodium and is present as mixed calcium sodium fluoride and sodium fluoride species. The addition of fluorine to bioglasses reduces the melting temperature which helps to minimize nitrogen loss and bubble formation. So the fluorine facilitates the dissolution of nitrogen into the melt. Nitrogen substitutes for oxygen in the silicate network and is present as SiO₃N and SiO₂N₂ structural units. The density, glass transition temperature, Young's modulus, hardness and fracture toughness all increase with the content of nitrogen introduced into the glasses. These changes are a result of greater cross-linking of the silicate network due to the higher coordination of nitrogen compared to oxygen.     

Inhibition of human carbonic anhydrase isoforms I–XIV with sulfonamides incorporating fluorine and 1,3,5-triazine moieties

Reaction of cyanuryl fluoride with sulfanilamide or 4-aminoethylbenzenesulfonamide afforded triazinyl-substituted benzenesulfonamides incorporating fluorine, which were further derivatized by reaction with amines, amino alcohols, amino acids or amino acid esters. Inhibition studies of all the human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms, hCA I–XIV with these compounds revealed that they show moderate-weak inhibition of hCA III, IV, VA and XIII, rather moderate inhibition against hCA I, VI, and IX, and excellent inhibition of the physiologically relevant hCA II, VII and XII. The inhibition profile of these fluorine containing triazinyl sulfonamides is thus very different from the corresponding analogs incorporating chlorine, which were previously investigated as inhibitors of some of these enzymes.