Synthesis and preliminary evaluation of a new fluorine-18 labelled triazine derivative for PET imaging of cannabinoid CB2 receptor

Cannabinoid CB2 PET tracers are considered as a promising alternative to PBR/TSPO tracers for the in-vivo imaging of neuroinflammation. We describe here the synthesis and characterization of compound 3, a new potent and brain penetrating CB2 ligand based on an original triazine template. The PET tracer [¹⁸F]-dideutero-3 was prepared in a three steps radiosynthesis, and demonstrated significant uptake in rhesus macaque and baboon brain with a maximum SUV of about 0.7–0.9 g/mL, followed by a moderate washout over time.     

Synthesis and evaluation of 99mTc–2-[(3-carboxy-1-oxopropyl)amino]-2-deoxy-d-glucose as a potential tumor imaging agent

The 2-[(3-carboxy-1-oxopropyl)amino]-2-deoxy-d-glucose (CPADG) was synthesized and radiolabeled with ^99mTcO₄⁻ to obtain the ^99mTc–CPADG complex in high yield. It was stable over 6 h in saline at room temperature and in serum at 37 °C. The partition coefficient and electrophoresis results indicated that the complex was hydrophilic and cationic. In vitro cell studies showed there was an increase in the uptake of ^99mTc–CPADG as a function of incubation time and ^99mTc–CPADG was possibly transported via the glucose transporters. The biodistribution of ^99mTc–CPADG in mice bearing S 180 tumor showed that the complex accumulated in the tumor with high uptake and good retention. The tumor/blood and tumor/muscle ratios increased with time and reached 1.91 and 5.05 at 4 h post-injection. Single photon emission computed tomography (SPECT) image studies showed there was an obvious accumulation in tumor sites, suggesting ^99mTc–CPADG would be a promising candidate for tumor imaging.     

Synthesis, [18F] radiolabeling,and evaluation of poly (ADP-ribose) polymerase-1 (PARP-1) inhibitors for in vivo imaging of PARP-1 using positron emission tomography

Imaging of poly (ADP-ribose) polymerase-1 (PARP-1) expression in vivo is a potentially powerful tool for developing PARP-1 inhibitors for drug discovery and patient care. We have synthesized several derivatives of benzimidazole carboxamide as PARP-1 inhibitors, which can be ¹⁸F-labeled easily for positron emission tomographic (PET) imaging. Of the compounds synthesized, 12 had the highest inhibition potency for PARP-1 (IC₅₀ = 6.3 nM). [¹⁸F]12 was synthesized under conventional conditions in high specific activity with 40–50% decay-corrected yield. MicroPET studies using [¹⁸F]12 in MDA-MB-436 tumor-bearing mice demonstrated accumulation of [¹⁸F]12 in the tumor that was blocked by olaparib, suggesting that the uptake of [¹⁸F]12 in the tumor is specific to PARP-1 expression.     

As_2O_3干预口腔鳞癌A431细胞EGFR表达的研究

目的：研究三氧化二砷（As2O3）对人口腔鳞癌A431细胞生长的抑制作用,探讨其抗肿瘤的机制。方法：合成特异性靶向到肿瘤细胞表面表皮生长因子受体（EGFR）的近红外荧光分子对比剂EGF-Cy5.5,验证试剂合成的靶向特异性。口腔鳞状细胞癌A431细胞系暴露于浓度分别为0μM,0.5μM,2.5μM和5.0μM的三氧化二砷溶液中0,24 h,48 h和72 h。共聚焦显微镜、流式细胞仪及免疫组化证实EGFR的表达水平,上述实验均测量三次,结果取平均值。结果：EGF-Cy5.5靶向荧光对比剂的标记率为68%~70%。对比对照组,越高浓度的三氧化二砷处理的肿瘤细胞其获得的细胞荧光信号强度越小,这与药物浓度越高细胞表面表达EGFR的量越少相一致。流式细胞仪显示,在72小时,作用于细胞的三氧化二砷药物浓度分别为0.5μM,2.5μM,和5.0μM,其相对应获得的细胞EGFR表达量分别为57.28±3.2%（P〈0.05）,29.91±2.2%（P〈0.01）和10.73±2.4%（P〈0.01）,明显低于对照组的细胞EGFR表达量74.42±1.8%,（P〈0.05）。结论：本研究应用近红外荧光分子成像的方法体外检测口腔鳞状细胞癌A431的EGFR表达水平,实验证明三氧化二砷对其EGFR具有明显的抑制作用,且抑制作用具有时间-剂量依赖性。     

全数字化X线摄影联合MR 动态增强检查诊断早期乳腺癌的 临床价值研究

摘要目的：分析早期乳腺癌的全数字X 线摄影与MRI影像学表现,评价全数字X 线摄影联合MRI 检查在早期乳腺癌诊断中的 临床价值。方法：回顾性分析2009 年10 月至2012 年5月在我院经穿刺或手术病理证实为早期乳腺癌的42例患者的临床资料, 术前均行数字X线及动态增强MR 检查,比较两种方法单独使用和联合使用的诊断乳腺癌的准确率。结果：全数字化X 线摄片 诊断早期乳腺癌的准确率为69.0%(29/42),动态增强MR 检查为95.2%(40/42),两者比较差异有统计学意义(P<0.05);两者联合使 用诊断早期乳腺癌的准确率为97.6%(41/42)。结论：动态增强MR 检查对早期乳腺癌的诊断价值明显优于全数字X线摄影,但后 者对微小钙化显示较好,两者联合可提高诊断正确率,尤其对多腺体型和致密型乳腺的早期乳腺癌的检出具有重要的价值。     

肝移植术后肝脏淋巴回流淤滞的影像学特征

目的:分析肝移植术后病人肝脏淋巴回流淤滞(intrahepatic lymphatic stasis,IHLS)的计算机断层扫描(Computed Tomography,CT)及磁共振(Magnetic Resonance Imaging,MRI)影像学特征。方法:回顾性收集我院自2004~2012年肝移植术后病人66例,分析其术后CT及MRI图像,对IHLS的阳性次数、持续时间及其影像学特征进行观察分析。结果:66病人中IHLS病人22例。肝移植术后IHLS的直接征象为血管周围项圈征(perivacular collar,PC),CT和MRI可清晰显示且可根据PC的部位分型。结论:肝移植术后IHLS的CT及MRI具有特定的影像学特征,对其识别具有一定的临床意义。     

Ca2+ Influx via the Na+/Ca2+ Exchanger Is Enhanced in Malignant Hyperthermia Skeletal Muscle

Malignant hyperthermia (MH) is potentially fatal pharmacogenetic disorder of skeletal muscle caused by intracellular Ca²⁺ dysregulation. NCX is a bidirectional transporter that effluxes (forward mode) or influxes (reverse mode) Ca²⁺ depending on cellular activity. Resting intracellular calcium ([Ca²⁺]_r) and sodium ([Na⁺]_r) concentrations are elevated in MH susceptible (MHS) swine and murine muscles compared with their normal (MHN) counterparts, although the contribution of NCX is unclear. Lowering [Na⁺]_e elevates [Ca²⁺]_r in both MHN and MHS swine muscle fibers and it is prevented by removal of extracellular Ca²⁺ or reduced by t-tubule disruption, in both genotypes. KB-R7943, a nonselective NCX3 blocker, reduced [Ca²⁺]_r in both swine and murine MHN and MHS muscle fibers at rest and decreased the magnitude of the elevation of [Ca²⁺]_r observed in MHS fibers after exposure to halothane. YM-244769, a high affinity reverse mode NCX3 blocker, reduces [Ca²⁺]_r in MHS muscle fibers and decreases the amplitude of [Ca²⁺]_r rise triggered by halothane, but had no effect on [Ca²⁺]_r in MHN muscle. In addition, YM-244769 reduced the peak and area under the curve of the Ca²⁺ transient elicited by high [K⁺]_e and increased its rate of decay in MHS muscle fibers. siRNA knockdown of NCX3 in MHS myotubes reduced [Ca²⁺]_r and the Ca²⁺ transient area induced by high [K⁺]_e. These results demonstrate a functional NCX3 in skeletal muscle whose activity is enhanced in MHS. Moreover reverse mode NCX3 contributes to the Ca²⁺ transients associated with K⁺-induced depolarization and the halothane-triggered MH episode in MHS muscle fibers.     

Single-molecule Imaging Analysis of Elementary Reaction Steps of Trichoderma reesei Cellobiohydrolase I (Cel7A) Hydrolyzing Crystalline Cellulose Iα and IIII

Trichoderma reesei cellobiohydrolase I (TrCel7A) is a molecular motor that directly hydrolyzes crystalline celluloses into water-soluble cellobioses. It has recently drawn attention as a tool that could be used to convert cellulosic materials into biofuel. However, detailed mechanisms of action, including elementary reaction steps such as binding, processive hydrolysis, and dissociation, have not been thoroughly explored because of the inherent challenges associated with monitoring reactions occurring at the solid/liquid interface. The crystalline cellulose I_α and III_I were previously reported as substrates with different crystalline forms and different susceptibilities to hydrolysis by TrCel7A. In this study, we observed that different susceptibilities of cellulose I_α and III_I are highly dependent on enzyme concentration, and at nanomolar enzyme concentration, TrCel7A shows similar rates of hydrolysis against cellulose I_α and III_I. Using single-molecule fluorescence microscopy and high speed atomic force microscopy, we also determined kinetic constants of the elementary reaction steps for TrCel7A against cellulose I_α and III_I. These measurements were performed at picomolar enzyme concentration in which density of TrCel7A on crystalline cellulose was very low. Under this condition, TrCel7A displayed similar binding and dissociation rate constants for cellulose I_α and III_I and similar fractions of productive binding on cellulose I_α and III_I. Furthermore, once productively bound, TrCel7A processively hydrolyzes and moves along cellulose I_α and III_I with similar translational rates. With structural models of cellulose I_α and III_I, we propose that different susceptibilities at high TrCel7A concentration arise from surface properties of substrate, including ratio of hydrophobic surface and number of available lanes.     

Molecular Basis Determining Inhibition/Activation of Nociceptive Receptor TRPA1 Protein: A SINGLE AMINO ACID DICTATES SPECIES-SPECIFIC ACTIONS OF THE MOST POTENT MAMMALIAN TRPA1 ANTAGONIST*

The transient receptor potential ankyrin 1 (TRPA1) is a Ca²⁺-permeable, nonselective cation channel mainly expressed in a subset of nociceptive neurons. TRPA1 functions as a cellular sensor detecting mechanical, chemical, and thermal stimuli. Because TRPA1 is considered to be a key player in nociception and inflammatory pain, TRPA1 antagonists have been developed as analgesic agents. Recently, by utilizing species differences, we identified the molecular basis of the antagonistic action of A967079, one of the most potent mammalian TRPA1 antagonists. Here, we show a unique effect of A967079 on TRPA1 from diverse vertebrate species, i.e. it acts as an agonist but not as an antagonist for chicken and frog TRPA1s. By characterizing chimeric channels of human and chicken TRPA1s, as well as point mutants, we found that a single specific amino acid residue located within the putative fifth transmembrane domain was involved in not only the stimulatory but also the inhibitory actions of A967079. AP18, structurally related to A967079, exerted similar pharmacological properties to A967079. Our findings and previous reports on species differences in the sensitivity to TRPA1 antagonists supply useful information in the search for novel analgesic medicines targeting TRPA1.