A new dosimeter based on ferrous sulphate solution and agarose gel

A new dosimeter made of ferrous sulphate solution and agarose gel has been developed. Due to a chain reaction in the agarose gel the sensitivity of the ferrous sulphate dosimeter is increased substantially. A G(Fe³⁺)-value up to almost 180 (100 eV)⁻¹ can be achieved. The G(Fe³⁺)-value and the linear dose response are dependent on the initial ferrous ion concentration. This dosimeter also has a uniform sensitivity over large volumes. The concentration of sulphuric acid has only minor influence on the sensitivity.     

The degradation of triazo dye chlorantine fast green BLL in aqueous solutions by gamma radiation—III

The radiation degradation yield (G_{d values}) of Chlorantine Fast Green BLL (CFGBLL), G_d, i.e. the value of moles of dye molecules degraded per joule of energy absorbed (sometimes given in units of the number of molecules decomposed per 100 eV of radiation energy absorbed) was measured in aerated, oxygen- and nitrogen-saturated aqueous solutions. The G_d values were found to be 0.063, 0.0715 and 0.033 μmol/J or (0.61, 0.69 and 0.32/100 eV) respectively. The relatively low degradation yield indicates the absence of chain reactions and probably the poor efficiency and economics, in terms of the practical application of the radiation process. For applications in the radiation treatment of waste water, it is noted that in the presence of oxygen and at higher concentration of CFGBLL, the value of G_d increases markedly, so that it may be practical to monitor the extent of sterilization of water. In addition the radiation processing of CFGBLL waste water may also become economically feasible. The specific bimolecular rate constant of the reaction of CFGBLL with the ^.OH was determined by studying the effect of ethanol concentration on G_d using competition kinetics. This rate constant was found to be k = 2.32 × 10¹⁰ and 1.65 × 10¹⁰ L mol/s at 610 and 380 nm wavelengths, respectively. Suggestions are made for the possible use of CFGBLL aqueous solution as a chemical dosimeter in the range of absorbed dose from 0.1 to 5 kGy.     

P53在电离辐射诱导的细胞周期解耦联中的作用

目的 探讨p53基因在电离辐射(IR)诱导的MCF-7细胞周期解耦联中的作用。 方法 构建RNAi表达载体,经磷酸钙共沉淀法转染293T细胞形成病毒包装颗粒,感染MCF-7后采用Western blot检测P53蛋白的表达,建立p53基因沉默模型。将p53野生型(+ +)和沉默模型(- -)经电离辐射处理后,采用流式细胞术分别测定细胞周期并分析细胞多倍体的变化。结果 与p53^{+ +}组比较,p53^{- -}模型组G₀ G₁期细胞百分数减少,S期、G₂期增加(P<0.01),倍体分析表明二倍体数减少,四倍体、八倍体均增加(P<0.01)。在p53^{+ +}和p53^{- -}细胞中,与假照射组比较,4 Gy照射后G₀ G₁期、S期细胞百分数减少,而G₂期增多(P<0.01);倍体分析表明,照射后二倍体数减少,四倍体、八倍体均增加(P<0.01)。与p53^{+ +}+IR组比较,p53^{- -}+IR 组发生G₀ G₁期、S期细胞百分数减少,G₂+M期增多(P<0.01),二倍体数减少,四倍体增多(P<0.01),八倍体无明显差别。结论 电离辐射可以诱导细胞发生G₂期阻滞和细胞周期解耦联;P53在电离辐射诱导的MCF-7细胞G₂期阻滞中发挥作用,而在细胞周期解耦联中可能不发挥作用。     

In vivo high-resolution magnetic resonance elastography of the uterine corpus and cervix

Objectives

To apply 3D multifrequency MR elastography (3DMMRE) to the uterus and analyse the viscoelasticity of the uterine tissue in healthy volunteers considering individual variations and variations over the menstrual cycle.

Methods

Sixteen healthy volunteers participated in the study, one of whom was examined 12 times over two menstrual cycles. Pelvic 3DMMRE was performed on a 1.5-T scanner with seven vibration frequencies (30–60 Hz) using a piezoelectric driver. Two mechanical parameter maps were obtained corresponding to the magnitude (|G ^* |) and the phase angle (φ) of the complex shear modulus.

Results

On average, the uterine corpus had higher elasticity, but similar viscosity compared with the cervix, reflected by |G ^* |_{uterine corpus}?=?2.58?±?0.52 kPa vs. |G ^* |_cervix?=?2.00?±?0.34 kPa (p?φ _{uterine corpus}?=?0.54?±?0.08, φ _cervix?=?0.57?±?0.12 (p?=?0.428). With 2.23?±?0.26 kPa, |G ^* | of the myometrium was lower in the secretory phase (SP) compared with that of the proliferative phase (PP, |G ^* |?=?3.01?±?0.26 kPa). For the endometrium, the value of |G ^* | in SP was 68 % lower than during PP (PP, |G ^* |?=?3.34?±?0.42 kPa; SP, |G ^* |?=?1.97?±?0.34 kPa; p?=?0.0061).

Conclusion

3DMMRE produces high-resolution mechanical parameter maps of the uterus and cervix and shows sensitivity to structural and functional changes of the endometrium and myometrium during the menstrual cycle.

Key Points

? MR elastography provided for the first time spatially resolved viscoelasticity maps of uterus. ? Uterine corpus had a higher elasticity, but similar viscosity compared with cervix. ? The stiffness of both endometrium and myometrium decreases during the menstrual cycle.     

High-pitch dual-source CT coronary angiography with low volumes of contrast medium

Objectives

To assess the effect of lower volumes of contrast medium (CM) on image quality in high-pitch dual-source computed tomography coronary angiography (CTCA).

Methods

One-hundred consecutive patients (body weight 65–85 kg, stable heart rate ≤65 bpm, cardiac index ≥2.5 L/min/m²) referred for CTCA were prospectively enrolled. Patients were randomly assigned to one of five groups of different CM volumes (G₃₀, 30 mL; G₄₀, 40 mL; G₅₀, 50 mL; G₆₀, 60 mL; G₇₀, 70 mL; flow rate 5 mL/s each, iodine content 370 mg/mL). Attenuation within the proximal and distal coronary artery segments was analysed.

Results

Mean attenuation for men and women ranged from 345.0 and 399.1 HU in G₃₀ to 478.2 and 571.8 HU in G₇₀. Mean attenuation values were higher in groups with higher CM volumes (P?<?0.0001) and higher in women than in men (P?<?0.0001). The proportions of segments with attenuation of at least 300 HU in G₃₀, G₄₀, G₅₀, G₆₀ and G₇₀ were 89 %, 95 %, 98 %, 98 % and 99 %. CM volume of 30 mL in women and 40 mL in men proved to be sufficient to guarantee attenuation of at least 300 HU.

Conclusions

In selected patients high-pitch dual-source CTCA can be performed with CM volumes of 40 mL in men or 30 mL in women.

Key Points

? High-pitch dual-source coronary angiography is feasible with low contrast media volumes. ? Traditional injection rules still apply: higher volumes result in higher enhancement. ? The patient’s gender is a co-factor determining the level of contrast enhancement. ? Volumes can be reduced down to 30–40 mL in selected patients.     

肺癌A549放射抗拒细胞亚系的建立及抗拒机制的研究

目的 建立肺癌细胞系A549的放射抗拒模型并探讨放射抗拒的机制。方法 应用两种方案对非小细胞肺癌A549细胞系进行X射线照射:一组照射5次,每次剂量600 cGy;另一组照射15次,每次剂量200 cGy。照射完成后对存活细胞单克隆化分别命名为A549-S1和A549-S2,采用克隆形成实验测定两种细胞亚系及亲本A549细胞的放射敏感性,流式细胞术检测细胞周期特征,RT-PCR和Western blot分别测定3种细胞Notch1的表达。结果 与亲本A549细胞相比,A549-S1细胞显示出明显放射抗性,D₀、D_q及N值增大,细胞存活曲线肩区增宽,在SF₂水平上,放射抗性是A549的1.38倍,细胞的S期比例较A549细胞明显增高, G₀/G₁期比例下降(P<0.05),Notch1的表达较A549细胞明显增强。而A549-S2的放射敏感性与亲本细胞相比稍增强,D₀、D_q及N值均减小,细胞存活曲线肩区变窄,在SF₂水平上,放射抗性是A549细胞的0.84倍,细胞S期、G₀/G₁期比例较A549细胞减少,而G₂/M期比例明显增加(P<0.05),Notch1表达与亲本A549细胞相比无明显变化。结论 A549细胞亚系放射抗拒的形成与不同照射方案有一定关系,得出的放射抗拒细胞亚系显示出与亲本不同的细胞周期特征,而细胞特征的变化可能与Notch1的表达增强有关。     

Ventricular muscarinic receptor remodeling in patients with and without primary ventricular fibrillation. An imaging study

Background

Vagal innervation modulates the electrical stability of the left ventricle (LV) during ischemia. Thus, abnormal parasympathetic activity in myocardial infarction (MI) patients with primary ventricular fibrillation (FV) can account for their arrhythmic disorders. We evaluated LV muscarinic receptor density (B _max) after MI in patients with (FV_G, n?=?11) or without (nFV_G, n?=?12) primary FV.

Methods and Results

The B _max was measured by positron emission tomography and the specific antagonist [¹¹C]methylquinuclidinyl benzilate ([¹¹C]MQNB) in 23 patients 39?±?19?days post-MI, and 10 volunteers. Myocardial damage was quantified by delayed contrast-enhanced magnetic resonance imaging. Three short-axis slices per subject were analyzed and six time-activity curves per slice were fitted to a 3-compartment ligand-receptor model. The B _max in remote regions of the 23 patients (67?±?36?pmol/mL?·?tissue; n?=?139) was higher than in normal regions of volunteers (33?±?16?pmol/mL?·?tissue; n?=?171; P?=?.01). Receptor density in remote regions was similarly upregulated in nFV_G (69?±?31?pmol/mL?·?tissue, n?=?73) and FV_G (66?±?40?pmol/mL?·?tissue, n?=?66; P?=?.72). In damaged regions, the B _max was reduced in both patient groups (44?pmol/mL?·?tissue).

Conclusions

Chronically infarcted patients with or without primary FV share similar patterns of ventricular muscarinic receptor remodeling, characterized by receptor upregulation, in remote non-damaged territories.     

Genistein induces radioprotection by hematopoietic stem cell quiescence

Purpose: In this study we addressed whether genistein-induced radioprotection in mice is associated with alterations of the cell cycle of hematopoietic stem and progenitor cells.

Materials and methods: C57BL/6J female mice received a single subcutaneous injection of genistein (200 mg/kg) 24 h prior to a lethal dose (7.75 Gy, ⁶⁰Co) of total body irradiation. Proliferation-associated Ki-67 protein/7-aminoactinomycin-D (Ki67/7AAD) cell cycle staining was used to differentiate between G₀, G₁, and S/G₂/M in bone marrow cell populations negative for expression of mature hematopoietic lineage marker cells but positive for expression of stem cell antigen-1 and tyrosine kinase receptor for stem cell factor (Lin^?Sca-1⁺cKit⁺, LSK⁺). Quantitative real-time polymerase chain reaction (qRT-PCR) microarrays were utilized to examine cell cycle specific genes.

Results: At 24 h following radiation exposure, a greater percentage of LSK⁺ in genistein-treated mice accumulated in the G₀ phase of the cell cycle, whereas a large percentage of LSK⁺ bone marrow cells from untreated and vehicle (PEG-400)-treated mice progressed into the G₁ and S/G₂/M phases. Moreover, the absolute number of marrow total LSK⁺, long-term LSK⁺, and short-term LSK⁺ increased 2.8, 12.1, and 4.2-fold, respectively, at 7 days post-irradiation in genistein-treated vs. untreated irradiated mice. Lin^? cells from genistein-treated mice expressed fewer DNA damage responsive and cell cycle checkpoint genes than LSK⁺ from untreated or vehicle-treated mice.

Conclusion: Pretreatment with genistein provides in vivo protection from acute myelotoxicity through extended quiescence followed by reduced senescence of marrow repopulating LSK⁺.     

Gamma-ray-induced chlorinative cleavage of SiSi bonds with carbon tetrachloride

Gamma-ray irradiation of carbon tetrachloride solution of polysilanes (C₆H₅Si(SiMe₃)₃, C₆H₅SiMe₂SiMe₃, C₆H₅MeSi(SiMe₃)₂, C₆H₅SiCl(Me)SiMe₂Cl, and C₆H₅SiMe₂SiMeCl₂) causes SiSi bond cleavage without serious side reactions. The small G-value of these compounds (G < 10) indicates that the reaction proceeds via a non-chain mechanism. The first step of this reaction is the attack of chlorine atoms on the SiSi bond, yielding chlorosilane and silyl radicals. The present method is milder than the conventional AIBN-initiated free-radical chlorination reaction with SO₂Cl₂.     

Pre-equilibrium decay process in the alpha induced reactions of silver isotopes

Excitation functions for the reactions ¹⁰⁷Ag(α,n)¹¹⁰In, ¹⁰⁷Ag(α,2n)¹⁰⁹In, ¹⁰⁹Ag(α,2n)¹¹¹In, ¹⁰⁹Ag(α,3n)¹¹⁰In and ¹⁰⁹Ag(α,4n)¹⁰⁹In have been measured from 13 to 50 MeV with the help of the stack-foil technique. Since the silver target used has two odd mass stable isotopes of about equal abundance, ¹⁰⁷Ag (51.83%) and ¹⁰⁹Ag (48.17%), in some cases the residual nuclei are the same through different reaction channels but the Q-values are different. In these cases the experimental cross-sections are separated out by using the ratio of theoretical cross-sections of the same reaction. The experimental results were compared with calculated values obtained by means of the geometry-dependent hybrid (GDH) model. The initial exciton number n₀ = 4 with different configurations was tested. It was found that the configuration (2n + 2p + 0h) appears to give a good fit to the experimental data.     

Etude des interactions In3+ligande par corrélation angulaire perturbée (CAP)

A perturbed angular correlation (PAC) study has been carried out to characterize the interactions between ¹¹¹In and citric acid as ligand. G₂₂(∞), (the coefficient of perburbation) as function of pH and ligand to     

西妥昔单抗增加结直肠癌细胞对125I粒子持续低剂量率照射的敏感性

目的 探讨在¹²⁵I 放射性粒子持续低剂量率照射下,西妥昔单抗对结直肠癌细胞CL187放射敏感性的影响及可能的机制。方法 实验将直肠癌细胞CL187分为空白对照组、单纯100 nmol/L C225处理组、单纯¹²⁵I -CLDR照射组和C225联合¹²⁵I -CLDR组。克隆形成实验检测C225是否影响人结直肠癌CL187细胞对¹²⁵I 放射性粒子持续低剂量率照射的放射敏感性。流式细胞仪检测C225对¹²⁵I -CLDR照射诱导的细胞凋亡的影响。细胞周期检测C225对细胞周期的调节。瑞氏姬姆萨染色检测有丝分裂指数。Western blot检测细胞内Bax、Bcl-2的水平。结果 100 nmol/L C225的放射增敏比为1.4,并能够增加¹²⁵I -CLDR照射诱导的细胞凋亡（t=6.6,P<0.05）,增加Bax/Bcl-2比值。与空白对照组相比,单独C225处理可使CL187细胞G₁期阻滞（t=3.0,P<0.05）,单纯¹²⁵I -CLDR照射组细胞也存在G₁期阻滞（t=8.5,P<0.01）,两者联合时的G₁期阻滞效应与¹²⁵I -CLDR单独处理时相比,差异无统计学意义（t=0.8,P>0.05）。有丝分裂指数检测结果显示,各实验组与对照组相比差异无统计学意义。结论 C225可增加结直肠癌细胞CL187对¹²⁵I -CLDR照射的放射敏感性,机制可能是C225增加细胞内Bax/Bcl-2比值,增加¹²⁵I-CLDR诱导的细胞凋亡,与细胞周期阻滞和细胞周期检查点功能无关。     

In-depth evaluation of the cycloaddition–retro-Diels–Alder reaction for in vivo targeting with [In]-DTPA-RGD conjugates

IntroductionThe spontaneous copper-free tandem 1,3-dipolar cycloaddition–retro-Diels–Alder (tandem crDA) reaction between cyclic Arg-Gly-Asp-d-Phe-Orn(N₃) [c(RGDfX)] and oxanorbornadiene-DTPA (o-DTPA) or methyloxanorbornadiene-DTPA (mo-DTPA) into two DTPA-c(RGDfX) regioisomers is characterized. Since there is no information on the stability and reaction rate of the tandem crDA reaction in biological media, we set out to characterize these reaction parameters.MethodsThe effects of concentration of the reactants, temperature, pH and reaction environment (serum, blood) on the kinetics of the reaction were determined using ¹¹¹In-labeled oxanorbornadiene-DTPA analogs. The affinity of the radiolabeled conjugate was determined in a solid-phase α_vβ₃ integrin binding assay. Furthermore, the octanol–water partition coefficient was determined and, finally, the biodistribution of the labeled compounds in mice with subcutaneous α_vβ₃-expressing tumors was determined.ResultsFifty percent conversion was reached after 26 h. Kinetic experiments furthermore established that the reaction rate of the tandem crDA reaction follows temperature- and concentration-dependent second-order kinetics, but is independent of the pH of the medium. Affinity of the two [¹¹¹In]DTPA-cRGDfX conjugates for α_vβ₃ integrin is 191 nM. Biodistribution studies showed specific (α_vβ₃-mediated) uptake of [¹¹¹In]DTPA-c(RGDfX) in the tumor and in α_vβ₃-expressing tissues.ConclusionThe tandem crDA reaction using methyl-substituted oxanorbornadiene is a versatile method for a single-step ligation that proceeds independently of pH and also proceeds in serum and blood. Currently, we are further looking into enhancement of reaction kinetics and exploitation of tandem crDA in vivo.     

Measurement of the G-value for 1·5 keV X-rays

Summary

Although there are several theoretical predictions of the dependence of the G-value on X-ray energy, measurements have not been made below ≈ 7 keV. Using a ferrous sulfate solution modified by the addition of benzoic acid, we have measured the relative G-values for Al_k characteristic X-rays (1·5 keV), ²³⁸Pu α-particles (3·7 MeV), ⁶⁰Co (1·17 MeV) and ¹³⁷Cs (0·66 MeV) γ-rays. This modified ferrous sulfate solution gave a 4-fold increase in sensitivity relative to the conventional solution, making measurements with the Al_k X-rays feasible. The relative ferrous-to-ferric conversions as a function of dose were similar for the two γ-ray energies, yielding G-values of 1·62 and 1·59 µmol J^?1 for the ⁶⁰Co and ¹³⁷Cs radiations, respectively. The α-particle G-value was 0·52 µmol J^?1, or 31 per cent of that for the ⁶⁰Co γ-rays, in good agreement with previous measurements. The Al_k X-rays had a G-value of 0·92 µmol J^?1 or 57 per cent of that of the ⁶⁰Co radiation. This G-value for the 1·5 keV X-rays is within 20 per cent of the values predicted by current theories, and theoretical values are within the error range of our measurement. The consistency between the experimental value reported here and theoretical G-values for ultrasoft X-rays should be valuable for models of radiation action on biological systems.     

Enhancing the efficacy of the 20 m multistage shuttle run test

Objective: Maximal oxygen uptake (Vo_2max) of 44 ml kg^–1 min^–1 is an accepted criterion (Vo_2CR) below which health and fitness for young male adults may be compromised. New algorithms validated for Vo_2CR screening using the 20 m multistage shuttle run test (20mMST) were developed.

Methods: Vo_2max was assessed in 110 males using a stationary gas analyser in a treadmill test (TT) and in 40 of these subjects using a portable gas analyser in the 20mMST. Vo_2max predicted from the 20mMST in 70 subjects was used for cross validation. Two equations predicting Vo_2max during 20mMST (EQ_MST) and TT (EQ_TT) were developed.

Results: Significant energy cost variance (EC_V) was detected between TT and 20mMST (p<0.001), correlated significantly with subject height, and was a significant predictor of Vo_2max differences between TT and 20mMST. The r² of EQ_MST was 0.92 (p<0.001). Predicted Vo_2max values from EQ_MST correlated with directly measured 20mMST Vo_2max at r = 0.96 (p<0.001). ANOVA detected no mean difference (p>0.05) between predicted and measured values. Prevalence of low fitness based on Vo_2CR was 0.37. McNemar χ² indicated significant differences in sensitivity (p<0.001) and specificity (p<0.05) between the original 20mMST equation (EQ_LÉG) and EQ_TT, regarding Vo_2CR screening. Cohen's κ demonstrated higher agreement with TT Vo_2max for EQ_TT (p<0.001) than EQ_LÉG (p<0.05). TT Vo_2max correlated with the end result of both EQ_LÉG and EQ_TT at r = 0.75 (p<0.001). Unlike EQ_TT (p>0.05), mean predicted Vo_2max from EQ_LÉG was significantly higher compared to TT Vo_2max (p<0.001).

Conclusion: These algorithms increase the efficacy of 20mMST to accurately evaluate aspects of health and fitness.

     

The formation of aqueous 111In complexes—I. A study using time-integral PAC and radiochromatography

Time integral PAC measurements have been made on aqueous samples of ¹¹¹InCl₃ as a function of both pH and also time after preparation of the ¹¹¹In. Additions to the active samples of cold CdCl₃, cold InCl₃ and one-year old Amersham product in 0.04 M HCl, were used to establish that the presence of cations in large and varying amounts was not responsible for the observed variability in G₂₂(∞) values. Likewise, the use of a number of different container materials and a consideration of competitive reactions between ¹¹¹In-tropolonate and various aqueous complexes which are expected to form, failed to provide a satisfactory explanation. The remaining hypothesis, that of a slow hydrolysis of the ¹¹¹In, receives support from the results of thin-layer radiochromatography measurements at pH values 1.1, 1.4 and 7.0.     

Synthesis of S-[13N]nitrosoglutathione (13N-GSNO) as a new potential PET imaging agent

In the present paper, a fast and reproducible method for the synthesis of S-[¹³N]nitrosoglutathione is reported for the first time. The labeling strategy is based on the production of [¹³N]NO₃⁻ via the ¹⁶O(p,α)¹³N nuclear reaction in water, as opposed to the standardized production of [¹³N]NH₄⁺ in 2 mM aqueous ethanol. Following the reduction of [¹³N]NO₃⁻ to [¹³N]NO₂⁻, the reaction with glutathione in the presence of hydrochloric acid led to the desired radiotracer with a good radiochemical yield (24.2±2.0% end of synthesis, n=5) in a short production time (3 min from the end of bombardment).     

Calculation of induced reactions of 3He-particles on natSb in 10–34 MeV energy range

Calculations for the excitation functions of the ¹²¹Sb(³He, xn) ^121,122,123I, and ¹²³Sb(³He xn) ^{122,123,124,125}I reactions have been carried out using statistical and pre-equilibrium nuclear reaction models in 10−34 MeV energy range. These excitation functions have been used to derive the excitation functions of the ^natSb(³He, xn)^121,123,124I reactions and compared with reported measurements. For studying the improvement with measurements two values of the diffuseness parameter a_w equal to 0.9 and 0.7 fm have been used in the calculations. The dependence of pre-equilibrium calculations on the initial exciton numbers has also been considered.     

<Superscript>99m</Superscript>TcO(MAG<Subscript>2</Subscript>-3G<Subscript>3</Subscript>-dimer): a new integrin α<Subscript>v</Subscript>β<Subscript>3</Subscript>-targeted SPECT radiotracer with high tumor uptake and favorable pharmacokinetics

Purpose  

This report presents the synthesis of a cyclic RGD dimer conjugate, MAG₂-G₃-E[G₃-c(RGDfK)]₂ (MAG₂-3G₃-dimer, G₃ = Gly-Gly-Gly, MAG₂ = S-benzoyl mercaptoacetylglycylglycyl), and evaluation of its ^99mTc complex, ^99mTcO(MAG₂-3G₃-dimer), as a new radiotracer for imaging the tumor integrin α_vβ₃ expression.     

A fast chemoenzymatic synthesis of [11C]-N5,N10-methylenetetrahydrofolate as a potential PET tracer for proliferating cells

IntroductionThymidylate synthase and folate receptors are well-developed targets of cancer therapy. Discovery of a simple and fast method for the conversion of ¹¹CH₃Ito[¹¹C]-formaldehyde (¹¹CH₂O) encouraged us to label the co-factor of this enzyme. Preliminary studies conducted on cell lines have demonstrated a preferential uptake of [11-¹⁴C]-(R)-N⁵,N¹⁰-methylene-5,6,7,8-tetrahydrofolate (¹⁴CH₂H₄folate) by cancerous cell vs. normal cells from the same organ (Saeed M., Sheff D. and Kohen A. Novel positron emission tomography tracer distinguishes normal from cancerous cells. J Biol Chem 2011;286:33872–33878), pointing out ¹¹CH₂H₄folate as a positron emission tomography (PET) tracer for cancer imaging. Herein we report the synthesis of ¹¹CH₂H₄folate, which may serve as a potential PET tracer.MethodsIn a remotely controlled module, methyl iodide (¹¹CH₃I) was bubbled into a reaction vial containing trimethylamine N-oxide in N,N-Dimethylformamide (DMF) and heated to 70°C for 2 min. Formaldehyde (¹¹CH₂O) formed after the completion of reaction was then mixed with a solution of freshly prepared tetrahydrofolate (H₄folate) by using a fast chemoenzymatic approach to accomplish synthesis of ¹¹CH₂H₄folate. Purification of the product was carried out by loading the crude reaction mixture on a SAX cartridge, washing with water to remove unbound impurities and finally eluting with a saline solution.ResultsThe synthesis and purification of ¹¹CH₂H₄folate were completed within 5 min. High-performance liquid chromatography analysis of the product after SAX purification indicates that more than 90% of the radioactivity that was retained on the SAX cartridge was in ¹¹CH₂H₄folate, with minor (<10%) radioactivity due to unreacted ¹¹CH₂O.ConclusionWe present a fast (～5 min) synthesis and purification of ¹¹CH₂H₄folate as a potential PET tracer. The final product is received in physiologically compatible buffer (100 mM sodium phosphate, pH 7.0 containing 500 mM NaCl) and ready for use in vivo.