尖锐湿疣患者中趋化因子受体CXCR1、CXCR4及其配体的水平

目的：测定趋化因子受体CXCR1与CXCR4及其配体在尖锐湿疣（CA）患者中的水平。方法：病程大于3个月的CA患者30例,实时定量PCR法检测外周血单个核细胞（PBMC）及皮损中CXCR1与CXCR4mRNA表达水平,流式细胞仪分析外周血白细胞CXCR1与CXCR4的表达情况,ELISA检测血清IL-8与SDF-1α的水平;设30例健康人为正常对照。结果：CX-CR4 mRNA与SDF-1α在CA患者中的水平显著高于对照组（均P〈0.01）。结论：CXCR4与SDF-1α可能参与了CA的发病机制。     

Synthesis and renal excretion of technetium-99m-labeled organic cations.

Organic cations are excreted more efficiently than organic anions in uremia suggesting superiority as renal imaging agents. In this study, three 99mTc-labeled cationic cyclam complexes were synthesized and their renal clearance quantified in rats. The complexes are cleared at a rate of about 2.5-3 times that of inulin and about 60% that of p-amino-hipurate. Inhibition of 99Tc-cyclam excretion by quinine indicates transport by the organic cation process. Comparative in vivo imaging experiments demonstrated that in normal rats 99mTc-cyclam reached peak renal activity 1.8 +/- 0.6 min after injection, a value intermediate between that for [131I]OIH (1.0 +/- 0) and 99mTc-MAG3 (2.8 +/- 0.6). In rats injected with the acute nephrotoxin cisplatin, the times to peak were lengthened with the relative order being 99mTc-cyclam > 99mTc-MAG3 > [131I]OIH. The results demonstrate that cationic complexes may be useful for renal imaging diagnostic applications.     

Evaluation of [11C]GB67, a novel radioligand for imaging myocardial alpha 1-adrenoceptors with positron emission tomography

Dysfunction of the sympathetic nervous system underlies a number of myocardial disorders. Positron emission tomography (PET) offers a way of assessing receptor function non-invasively in humans, but there are no PET radioligands for assessing myocardial alpha-adrenoceptors. GB67, a structural and pharmacological analogue of the alpha 1-adrenoceptor antagonist prazosin, was labelled with positron-emitting carbon-11 (t1/2 = 20.4 min) by 11C-methylation of N-desmethylamido-GB67 (GB99). [11C]GB67 was injected intravenously into conscious rats. Serial arterial blood samples were taken. Rats were killed and tissues removed to determine radioactivity. The percentages of unchanged [11C]GB67 and its radioactive metabolites in plasma and tissues were assessed by HPLC. Plasma clearance of radioactivity was rapid. Myocardial uptake was maximal at 1-2 min and decreased slowly during 60 min. Predosing with adrenoceptor antagonists demonstrated selectivity for myocardial alpha 1-adrenoceptors. GB67 and prazosin blocked uptake of radioactivity; the non-selective antagonist, phentolamine, partially blocked uptake; the alpha 2-adrenoceptor antagonist, RX 821002, only blocked uptake at high dose and the beta-adrenoceptor antagonist, CGP 12177, had no effect. Additionally, injection of prazosin at 20 min after radioligand displaced radioactivity. In vivo competition curves obtained by injecting [11C]GB67 with varying amounts of either unlabelled GB67 or its precursor GB99 were fitted to a competitive binding model to provide estimates of the maximum number of binding sites (Bmax) and half saturation doses (K) for myocardium. Assuming a tissue protein content of 10%, the values of Bmax [approximately 13 pmol.(g tissue)-1[ were similar to those ]50-170 fmol.(mg protein)-1] reported for myocardial alpha 1-adrenoceptors assessed in vitro. Both GB67 and its precursor GB99 had high affinity for alpha 1-adrenoceptors [KGB67 = 1.5 nmol.(kg body weight)-1, KGB99 = 4.8 nmol.(kg body weight)-1]. HPLC demonstrated four radioactive metabolites in plasma. [11C]GB67 was 80% of the radioactivity at 5 min and 50% at 45 min. No radioactive metabolites were detected in myocardium up to 60 min after injection. [11C]GB67 was assessed in two male human volunteers. PET demonstrated high myocardial uptake. The profile of radioactive metabolites in plasma was comparable to that in the rat, although metabolism was slower in humans. Thus, [11C]GB67 is a promising radioligand for assessing alpha 1-adrenoceptors in human myocardium with PET.     

基质细胞衍生因子-1α在诱导骨髓来源细胞到达皮肤创面中的作用

目的 探讨皮肤创面基质细胞衍生因子-1α(stromal cell derived factor-1α,SDF-1α)在诱导骨髓来源细胞(bone marrow derived cells,BMDCs)向创面募集过程中的作用.方法分离培养小鼠BMDCs,并通过CXCR=4(SDF-1d特异性受体)免疫荧光鉴定BMDCs.培养的BMDC8分为正常培养组(BMDCs组)和CXCR4抗体共孵育组(100 ng/ml,anti-CXCR4组),用CM-DiI标记后分别将各组BMDC8注入全层皮肤缺损伤小鼠模型的尾静脉,同时以注射DMEM/F12无血清培养基作为对照组,观察创面标记的BMDCs数量及创面愈合率. 结果 (1)BMDCs均表达CXCR4;(2)在伤后7和14 d BMDCs组的创面愈合率分别为(41.3±4.6)%和(92.3±2.1)%,显著高于相应时相点对照组[(29.3±2.3)%、(77.3±2.5)%]和anti-CXCR4组[(30.7±4.6)%、(85.7±1.5)%](P＜0.05),而anti-CXCR4组的创面愈合率仅在伤后14 d显著高于对照组(P＜0.05);(3)在伤后7和14 d,BMDCs组创面标记的BMDCs数目分别为(535±84)个/每张切片和(769±124)个/每张切片,显著高于相应时相点的anti-CXCR4组[(335±97)个/每张切片;(521±127)个/每张切片](P＜0.05). 结论 BMDCs参与并促进皮肤创面愈合;SDF-1α在诱导BMDCs到达创面过程中有重要作用.     

SDF-1／CXCR4在妊娠期高血压疾病中的表达及意义

目的研究SDF-1／CXCR4在正常妊娠及妊娠期高血压疾病胎盘中的表达和血清水平。方法采用免疫组织化学SP法检测60例孕妇（妊娠期高血压、轻度先兆子痫、重度先兆子痈和正常妊娠组各15例）胎盘组织中SDF-1／CXCR4表达程度,同时用ELISA检测孕妇血清中SDF-1的浓度水平。结果SDF-1在妊娠期高血压组及正常妊娠组的胎盘组织中均有表达,在子痫前期组中呈弱阳性或阴性表达。妊娠高血压组与正常妊娠组血清SDF-1水平无显著差异（P〉0．05）,轻度子痫前期组及重度子痫前期组SDF-1水平明显低于正常妊娠组（P〈0．001）。结论SDF—1／CXCR4可能在妊娠期高血压疾病的发病中发挥重要作用。     

99mTc-labeled mannosyl-neoglycoalbumin for sentinel lymph node identification

99mTc-labeled mannosyl-neoglycoalbumin (NMA) was prepared and evaluated as a radiopharmaceutical for sentinel lymph node (SLN) identification, since 99mTc-labeled human serum albumin (HSA) rapidly cleared from injection sites. NMA was conjugated with 6-hydrazinopyridine-3-carboxylic acid (HYNIC) and reacted with [99mTc](tricine)2 to prepare [99mTc](HYNIC-NMA)(tricine)2. After subcutaneous injection of [99mTc](HYNIC-NMA)(tricine)2 from murine foot pad, radioactivity levels in the popliteal and lumbar lymph nodes, the injection site and other tissues were compared with those of [99mTc](HYNIC-HSA)(tricine)2 and 99mTc-labeled colloidal rhenium sulfate ([99mTc]colloid). [99mTc](HYNIC-NMA)(tricine)2 demonstrated significantly higher radioactivity levels in the popliteal lymph node, the SLN in this model, than did [99mTc](HYNIC-HSA)(tricine)2 and [99mTc]colloid at 0.5, 1, and 6 h post-injection. [99mTc](HYNIC-NMA)(tricine)2 showed a dose-dependent decrease in the popliteal accumulation while the radioactivity levels in the blood, liver and spleen increased with an increase in the molar dose of NMA. [99mTc]colloid registered a decrease in the radioactivity levels in the popliteal lymph node, blood, liver, and spleen with dilution. However, the radioactivity levels at the injection site increased with dilution of [99mTc] colloid. Both [99mTc](HYNIC-NMA)(tricine)2 and [99mTc](HYNIC-HSA)(tricine)2 showed the radioactivity levels at the injection site similar each other. These findings indicated that an addition of a macrophage binding function to 99mTc-labeled HSA provided high and selective accumulation of the radioactivity in the SLN without affecting the elimination rate from the injection site. Such characteristics render [99mTc](HYNIC-NMA)(tricine)2 attractive as a radiopharmaceutical for SLN identification. This study also demonstrated that the number of non-radiolabeled colloidal particles and the molar dose of mannosylated compounds play a crucial role in the SLN accumulation.     

Radiation dose from radiopharmaceuticals contaminated with molybdenum-99

Sixteen patients undergoing routine nuclear imaging procedures were injected with 99mTc-labeled radiopharmaceuticals containing 99Mo which exceeded the recommended limit of 1 microCi of 99mMo per mCi of 99mTc. The kinetics of the resulting 99Mo distribution in 14 of these patients were studied over a period of several weeks. The mean biologic half-life [T 1/2b] ranged from about 19.3 days to 11.2 days depending on the model used. Similarly, the mean radiation dose to the liver ranged from approximately 0.02 rad/microCi of 99Mo to 0.05 microCi of 99Mo.     

Excretion of radionuclides in human breast milk after the administration of radiopharmaceuticals

The fraction of injected activity that was excreted through the breast milk of nursing mothers at different times after the injection of various radiopharmaceuticals has been measured in 21 patients. For 99mTc-labeled radiopharmaceuticals the total excreted fraction was 10% for pertechnetate and 1.5-3% for MAA, plasmin, diethylenetriaminepentaacetic acid (DTPA), and methylene diphosphonate (MDP). For [125I]hippuran and [131I]hippuran the corresponding value was 3%. For the above mentioned radiopharmaceuticals the activity concentration in the milk decreased exponentially with an effective half-life of approximately 4 hr. For chromium-51 ethylenediaminetetraacetic acid ([51Cr]EDTA) and [99mTc]RBC, much smaller amounts were excreted in the breast milk. The absorbed dose to various organs of the baby has been calculated. We conclude that when [99mTc]pertechnetate, [99mTc]MAA, [99mTc]plasmin, [125I]hippuran, or [131I]hippuran are used the child should be fed just before the administration of the radionuclide to the mother and the next three milk fractions should not be used. For [99mTc]DTPA and [99mTc]MDP as well as [51Cr]EDTA, only the first fraction should not be used. According to our earlier investigations breast feeding has to be stopped for at least 3 wk after investigations with [125I]fibrinogen.     

Development of a Tc-99m labeled sigma-2 receptor-specific ligand as a potential breast tumor imaging agent

A novel in vivo imaging agent, 99mTc labeled [(N-[2-((3'-N'-propyl-[3,3,1]aza-bicyclononan-3alpha-yl)(2"-methoxy-5-methyl-phenylcarbamate)(2-mercaptoethyl)amino)acetyl]-2-aminoethanethiolato] technetium(V) oxide), [99mTc]2, displaying specific binding towards sigma-2 receptors was prepared and characterized. In vitro binding assays showed that the rhenium surrogate of [99mTc]2, Re-2, displayed excellent binding affinity and selectivity towards sigma-2 receptors (K(i) = 2,723 and 22 nM for sigma-1 and sigma-2 receptor, respectively). Preparation of [99mTc]2 was achieved by heating the S-protected starting material, 1, in the presence of acid, reducing agent (stannous glucoheptonate) and sodium [99mTc]pertechnetate. The lipophilic racemic mixture was successfully prepared in 10 to 50% yield and the radiochemical purity was >98%. Separation of the isomers, peak A and peak B, was successfully achieved by using a chiralpak AD column eluted with an isocratic solvent (n-hexane/isopropanol; 3:1; v/v). The peak A and peak B appear to co-elute with the isomers of the surrogate, Re-2, under the same HPLC condition. Biodistribution studies in tumor bearing mice (mouse mammary adenocarcinoma, cell line 66, which is known to over-express sigma-2 receptors) showed that the racemic [99mTc]2 localized in the tumor. Uptake in the tumor was 2.11, 1.30 and 1.11 %dose/gram at 1, 4 and 8 hr post iv injection, respectively, suggesting good uptake and retention in the tumor cells. The tumor uptake was significantly, but incompletely, blocked (about 25-30% blockage) by co-injection of "cold" (+)pentazocine or haloperidol (1 mg/Kg). A majority of the radioactivity localized in the tumor tissue was extractable (>60%), and the HPLC analysis showed that it is the original compound, racemic [99mTc]2 (>98% pure). The distribution of the purified peak A and peak B was determined in the same tumor bearing mice at 4 hr post iv injection. The tumor uptake was similar for both isomers, but the blood and peripheral tissue content for the isomer in peak B was higher than that for the isomer in peak A. It is evident that the isomer in peak A displayed significantly better tumor/blood and tumor/muscle ratios. The higher rate of in vivo metabolism was also confirmed by the higher thyroid uptake values for the isomer in peak B as compared to peak A. In summary, a 99mTc-labeled sigma receptor imaging agent, [99mTc]2, has demonstrated the feasibility of using a 99mTc-labeled agent for imaging sigma receptor expression in tumor cells. This is the first time a subtype-selective 99mTc-labeled agent for imaging sigma receptor sites is reported.     

Synthesis and biodistribution of radiolabeled alpha 7 nicotinic acetylcholine receptor ligands.

Our objective was to develop an array of alpha(7)-selective nicotinic cholinergic receptor (nAChR)-based imaging agents for PET and SPECT. METHODS: (2'R)-N-(11)C-Methyl-N-(phenylmethyl)-spiro[1-azabicyclo[2.2.2]octane-3,2'(3'H)-furo[2,3-b]pyridin]-5'-amine 1 was synthesized by reaction of the corresponding desmethyl precursor with (11)C-CO(2) and reduction. N-(R)-1-Aza-bicyclo[2.2.2]oct-3-yl-4-(11)C-methylsulfanyl-benzamide 2 was synthesized by reduction of the corresponding disulfide precursor and reaction with (11)C-iodomethane. N-(R)-1-Aza-bicyclo[2.2.2]oct-3-yl-4-(125)I-iodo-benzamide 3 was synthesized by halogen exchange of the corresponding bromide. (2'R)-5'-(2-(125)I-iodo-3-furanyl)spiro[1-azabicyclo[2.2.2]octane]-3,2'(3'H)-furo[2,3-b]pyridine 4 was synthesized by the chloramine-T method. Kinetic biodistribution studies were done in male CD-1 mice by tail vein injection of 3.7 MBq (100 microCi) of the (11)C-labeled radiotracer or 0.67 MBq (2 microCi) of the (125)I-labeled radiotracer followed by brain dissection and tissue counting. Receptor blockade was determined by pretreatment of the mice with an excess of either unlabeled precursor or nicotine. RESULTS: We synthesized 4 radiolabeled, moderate- to high-affinity, alpha(7)-nAChR-based ligands. The compounds were a series of quinuclidine derivatives with an inhibition constant (K(i)) < 6 nmol/L (33 pmol/L for 4) for alpha(7)-nAChR and selectivities of alpha(7)/alpha(4)beta(2) subtypes of > or =14,000. All of the compounds were produced in adequate radiochemical yield and specific radioactivity (>74 GBq/micromol [2,000 Ci/mmol]). No site selectivity or receptor blockade was shown for 1 and 2 (0.91 +/- 0.05 and 0.14 +/- 0.03 %ID/g [percentage injected dose per gram] in the hippocampus [target tissue], respectively). Compound 3 showed low hippocampal uptake (0.25 +/- 0.05 %ID/g) but prolonged retention within that structure. Pretreatment with nicotine decreased its uptake by up to 50% in the hippocampus. Similar reductions were also observed within the cerebellum (nontarget tissue). Compound 4 showed hippocampal uptake of 2.41 +/- 0.03 %ID/g and target-to-nontarget uptake ratios of up to 2. Pretreatment of animals with unlabeled 4 resulted in a decrease of hippocampal uptake to 60% of its preblockade value without a corresponding decrease in cerebellar uptake. CONCLUSION: With further structural optimization, selective imaging of alpha(7)-nAChR may be possible.     

[99mTc]O2-AMD3100 as a SPECT tracer for CXCR4 receptor imaging

PurposeCXCR4 plays an important role in HIV infection, tumor progression, neurogenesis, and inflammation. In-vivo imaging of CXCR4 could provide more insight in the role of this receptor in health and disease. The aim of this study was to investigate [^99mTc]O₂-AMD3100 as a potential SPECT tracer for imaging of CXCR4.MethodAMD3100 was labelled with [^99mTc]pertechnetate. A cysteine challenge assay was performed to test the tracer stability. Heterologous and homologous receptor binding assay and internalization assay were performed in CXCR4 expressing Jurkat-T cells. Ex vivo biodistribution was studied in healthy mice at 30, 60, and 120 min after tracer injection. Tumor uptake of the tracer was determined by microSPECT imaging in nude mice xenografted with human PC-3 prostate tumor. Specificity of tracer uptake was determined by blocking studies using an excess of unlabelled AMD3100.ResultsAMD3100 was labelled with technetium-99 m with a radiochemical yield of > 98%. The tracer was stable in PBS and mouse plasma for at least 6 h at 37 °C. Heterologous and homologous binding assays with AMD3100 showed IC₅₀ values of 240 ± 10 μM, and 92 ± 5 μM for [¹²⁵I]SDF-1α and [^99mTc]O₂-AMD3100 respectively, with negligible receptor internalisation. The tracer showed high uptake in liver, lungs, spleen, thymus, intestine and bone. Blocking dose of AMD3100.8HCl (20 mg/kg) decreased the uptake in these organs (p < 0.05). [^99mTc]O₂-AMD3100 showed specific tumor accumulation in mice bearing PC-3 xenografts model. Time activity curves (TAC) in AMD3100 pre-treated animals tracer showed 1.7 times less tumor uptake as compared to control animals (p < 0.05).Conclusion[^99mTc]O₂-AMD3100 is readily labelled, is stable in plasma and displays a favourable binding affinity for the CXCR4 receptors. [^99mTc O₂-AMD3100 shows specific binding in organs with high CXCR4 expression and in CXCR4 positive tumors. These results justify further evaluation of this radiopharmaceutical as a potential biomarker for the non-invasive imaging of CXCR4 receptors.     

99mTc-labeled antimicrobial peptides for detection of bacterial and Candida albicans infections.

This study compared the possibilities and limitations of 99mTc-labeled synthetic peptides derived from two human antimicrobial peptides, namely, ubiquicidin (UBI) and lactoferrin (hLF), for the scintigraphic detection of bacterial and fungal infections in mice and rabbits. The rationale of our approach was that selected peptides accumulate in infected areas but not in sterile inflammatory lesions, because they bind preferentially to microorganisms. 99mTc-labeled human neutrophil peptides (defensins), ciprofloxacin, and human polyclonal IgG were included as control agents. METHODS: 99mTc-labeled peptides and control agents were injected intravenously into animals that had been injected intramuscularly 18 h earlier with multidrug-resistant Staphylococcus aureus, Klebsiella pneumoniae, or fluconazole-resistant Candida albicans. Sterile inflammatory sites were induced by the injection of heat-killed microorganisms or lipopolysaccharide (LPS) into the thigh muscle. Up to 4 h after injection, the accumulation of 99mTc-labeled compounds in the infected/inflamed thigh muscles was determined using scintigraphic techniques and radioactivity counts in dissected tissues. RESULTS: Scintigraphy revealed that 99mTc-labeled peptides UBI 29-41, UBI 18-35, UBI 31-38, hLF 1-11, and defensins, which showed preferential in vitro binding to microorganisms in a former study, accumulated at a significantly higher rate (P < 0.01) in bacterial and C. albicans infections in mice and rabbits than in inflamed tissues induced by heat-killed microorganisms or by LPS. No significant difference in the accumulation of 99mTc-labeled ciprofloxacin was observed between infected and sterile inflamed thigh muscles in mice. CONCLUSION: 99mTc-labeled antimicrobial peptides UBI 29-41, UBI 18-35, UBI 31-38, hLF 1-11, and defensins accumulate significantly in tissues infected with gram-positive and gram-negative bacteria and C. albicans. Significantly lower (P < 0.01) accumulation of these peptides occurs in sterile inflamed tissues. These data indicate that the peptides preferentially tag microorganisms at the site of infection, which is in agreement with their preferential binding to the microorganisms in vitro and in vivo. 99mTc-labeled ciprofloxacin does not distinguish between infections and sterile inflammatory lesions, which implies that its specificity for the detection of bacterial infections is not warranted.     

Joint scintigraphy in rabbits with 99mtc-N-[3-(triethylammonio)propyl]-15ane-N5, a new radiodiagnostic agent for articular cartilage imaging.

The aim of this study was to investigate joint scintigraphy in rabbits with 99mTc-N-[3-(triethylammonio)propyl]-15ane-N5 (NTP 15-5), a new radiopharmaceutical that specifically localizes in cartilaginous tissues. METHODS: Scans obtained after intravenous injection of the 99mTc-labeled compound in normal and arthropathy-induced rabbits were compared with those of the bone-imaging agent 99mTc-methylene diphosphonate (99mTc-MDP). RESULTS: The radioactive uptake of 99mTc-NTP 15-5 was detected in cartilaginous tissues 5 min after injection and was stable for 2 h. The uptake intensity was related to age and joint disease severity, and cartilage alterations not revealed by radiography induced a significant decrease of radiotracer uptake. On the other hand, imaging performed with 99mTc-MDP did not reveal the early changes in arthrosis but was more specific for bone remodeling in advanced stages of diseases or in inflammatory processes. CONCLUSION: Our results indicate that 99mTc-NTP 15-5 could be a good tracer for human arthrosic and arthritic cartilage detection, especially for the early diagnosis of joint diseases.     

miR-1抑制SDF-1表达和分泌调控HMSC-bm向肝癌细胞迁移

目的 明确肿瘤抑制性micro RNA-1（miR-1）能否通过抑制SDF-1的表达和分泌,调控骨髓间充质干细胞（HMSC-bm）向肿瘤组织的转移.方法 （1）分别利用miR-1表达质粒pSuper-miR-1和miR-1反义寡核苷酸,在肝癌细胞系HepG2中过表达或下调miR-1,Western blot和酶联免疫吸附实验分别检测肝癌细胞蛋白裂解物和培养上清液中SDF-1的表达和分泌水平;（2）构建融合SDF-1 3UTR的pGL3重组萤光素酶报告基因载体,将其与pSuper-miR-1共转染HEK293细胞,利用双萤光报告基因检测系统检测重组萤光素酶的表达情况.（3）利用pSuper-miR-1或miR-1反义寡核苷酸转染接种于Transwell下层小室的HepG2细胞过表达miR-1或下调miR-1水平,检测TransweH上层小室HMSC-bm向下层小室HepG2肝癌细胞的迁移情况.结果 （1）在肝癌细胞,HepG2过表达miR-1能够显著抑制SDF-1蛋白表达和分泌,而下调miR-1水平则能够诱导SDF-1的表达和分泌.（2） miR-1能够抑制携带SDF-1 3UTR的pGL3重组萤光素酶报告基因活性.（3）在Transwell下层小室的HepG2细胞中过表达miR-1后,上层小室中HMSC-bm向下层小室迁移细胞数量显著减少,而下调下层小室HepG2细胞中miR-1表达水平,则明显增加HMSC-bm向HepG2肝癌细胞的迁移.结论 miR-1能够直接抑制肝癌细胞SDF-1的表达和分泌,并藉此降低肝癌细胞对HMSC-bm的趋化作用.     

Imaging paclitaxel (chemotherapy)-induced tumor apoptosis with 99mTc C2A, a domain of synaptotagmin I: a preliminary study

PURPOSE: To evaluate the dynamics and feasibility of imaging non-small cell lung cancer (NSCLC) apoptosis induced by paclitaxel treatment using 99mTc-labeled C2A domain of synaptotagmin I in a mouse model. MATERIALS AND METHODS: H460 tumor-bearing mice were treated with intravenous paclitaxel, and 12, 24, 48 and 72 h later, 99mTc-C2A-GST was injected intravenously, and planar images were acquired at 2, 4 and 6 h postinjection on a dual-head gamma camera fitted with a pinhole collimator. Tumor-to-normal tissue ratios (T/NT) were calculated by ROI analysis and reflected specific binding of 99mTc-C2A-GST. Mice were sacrificed after 6-h imaging; caspase-3 as apoptosis executer was determined by flow cytometry; DNA fragmentation was analyzed by terminal deoxynucleotidytransferase mediated dUTP nick-end labeling (TUNEL) assay. Whereas nonspecific accumulation was estimated using inactivated C2A-GST. The imaging data were correlated with TUNEL-positive nuclei and caspase-3 activity. RESULTS: T/NT significantly increased after paclitaxel inducement, whereas it was low in untreated tumors (T/NT=1.24+/-0.23). In terms of % ID/g, activity in Group 2 (12 h), Group 3 (24 h), Group 4 (48 h) and Group 5 (72 h) after the treatment was 2.05+/-0.20, 3.02+/-1.01, 3.17+/-1.16 and 3.96+/-1.72, respectively. Whereas in the nontreated group, Group 1 % ID/g was 1.21+/-0.51. The radiotracer uptake was positively correlated to the apoptotic index (r=0.70, P<.01), as well as caspase-3 activity (r=0.75, P<.01). CONCLUSION: This study addresses the dynamics and feasibility of imaging non-small cell lung tumor apoptosis using 99mTc-labeled C2A.     

Experimental study on radioactive pathways of hypodermically injected technetium-99m.

The objective of this study was to investigate the biological substrate of radioactive pathways of migration of hypodermically injected 99mTc into points of low electrical resistance. Sixteen anesthetized adult male beagles were used. Control and test points were defined by comparing their electrical resistance to that of the pinna. Seventy-three experiments of three different types were performed: (1) separate hypodermic injections of [99mTc] sodium pertechnetate, 201Tl-chloride, 131INa and 99mTc-rhenium sulfide into control and test points; (2) simultaneous injections of [99mTc]sodium pertechnetate and 201Tl chloride into control and test points; and (3) intravascular injections of 99mTcO4 into blood vessels underlying test points. Only the hypodermic injection of 99mTc into points of low electrical resistance gave rise to a specific radioactive pathway characterized by rapid and longitudinal migration, clearly independent of background activity. The specific radioactive pathway detected is not the result of diffusion of the radiotracer through nerves, veins or lymphatic vessels, but its trajectory coincides with that described for one of the acupuncture meridians in the dog.     

Production of multimeric prostate-specific membrane antigen small-molecule radiotracers using a solid-phase 99mTc preloading strategy.

Small-molecule ligands specific for prostate-specific membrane antigen (PSMA) have the potential to improve prostate cancer imaging. However, highly charged ligands are difficult to label with 99mTc and to purify. In this study, we present an adamantane-trimerized small molecule that has nanomolar binding to PSMA and also has 12 negative charges. METHODS: To convert this molecule into a clinically viable SPECT diagnostic, we have developed a simple, cartridge-based, solid-phase prelabeling strategy that, within 25 min, converts readily available and inexpensive 99mTc-pertechnetate into a chemically pure complex, with a reactive N-hydroxysuccinimide (NHS) ester, in neat organic solvent. This stable intermediate can label any amine-containing small molecule or peptide with 99mTc in 1 step, with high specific activity and without the need for high-performance liquid chromatography (HPLC). RESULTS: Solid-phase conversion of 99mTc-pertechnetate to 99mTc-MAS3-NHS (MAS3 is S-acetylmercaptoacetyltriserine) could be completed in 25 min, with >99% radiochemical purity and with no coligands present. This intermediate was then conjugated to adamantane-trimerized GPI (2[(3-amino-3-carboxypropyl)(hydroxy)(phosphinyl)-methyl]pentane-1,5-dioic acid) in 1 step with >95% yield and no need for HPLC purification. The final molecule bound specifically to living human tumor cells expressing PSMA on their surface. Quantitative comparison was made among GPI monomer, GPI trimer, and their 99mTc-derivatives. CONCLUSION: Our study describes a simple cartridge-based conversion of 99mTc-pertechnetate to a useful, preloaded NHS ester intermediate that takes only 25 min to prepare and results in >99% radiochemical purity. Using this chemistry, we produced a high-specific-activity, 99mTc-labeled, PSMA-targeted small molecule and demonstrate gamma-ray radioscintigraphic imaging of living human prostate cancer cells.     

Biodistribution, dosimetry, and clinical evaluation of technetium-99m ethyl cysteinate dimer in normal subjects and in patients with chronic cerebral infarction

Technetium-99m ethyl cysteinate dimer (ECD) has high initial cerebral uptake with slow clearance in nonhuman primates suggesting ideal characteristics for single photon emission computer tomography (SPECT) imaging. We evaluated the biodistribution, dosimetry and scintigraphic pattern of [99mTc]ECD in normal subjects and the accuracy of SPECT imaging in patients with chronic cerebral infarction. Sixteen normal subjects were injected with approximately 10 mCi of [99mTc]ECD. Anterior and posterior single-pass whole-body images were obtained at multiple times after injection. Blood clearance of the radiotracer was rapid, falling to 10.0 +/- 6.6% and 4.9 +/- 1.1% of the injected dose at 2 and 60 min, respectively. Brain uptake was 6.4 +/- 2.1% of the injected dose 5 min after injection. The critical organ was the urinary bladder. Technetium-99m ECD SPECT was performed with a rotating gamma camera in ten of the 16 normal subjects and 34 patients with clinical and CT evidence of chronic stroke. Thirty-three of the thirty-four patients had focal [99mTc]ECD abnormalities on SPECT (97.1%) based on visual inspection of the SPECT images. In summary, we obtained high quality SPECT images as a result of the optimal physical and biologic characteristics of the tracer. Technetium-99m ECD SPECT shows promise for the evaluation of patients with stroke.     

Effect of reperfusion and hyperemia on the myocardial distribution of technetium-99m t-butylisonitrile

Technetium-99m t-butylisonitrile ([99mTc]TBI) is a promising new radiotracer for myocardial imaging. Its myocardial uptake is sufficiently high in humans to permit planar, tomographic, and gated images of excellent technical quality. We studied the behavior of [99mTc]TBI in the dog at rest and under conditions of hyperemia and reperfusion in order to determine the relationship between [99mTc]TBI myocardial concentration and blood flow. After permanent occlusion of the left anterior descending artery, the correlation between the relative myocardial concentration of [99mTc]TBI and regional myocardial blood flow (RMBF) measured with radiolabeled microspheres was excellent. In a dog model of transient hyperemia, the concentration of [99mTc]TBI was directly related to blood flow but underestimated the degree of hyperemia. Technetium-99m TBI redistributed into transiently ischemic myocardium. The myocardial concentrations of [99mTc]TBI and thallium-201(201TI) in transiently ischemic myocardium were similar at 10 and 30 min following reperfusion and were significantly higher than blood flow prior to reperfusion. When [99mTc]TBI was injected into the left anterior descending artery, the washout was slow, falling to 78% of initial activity at 120 min after injection. In conclusion, [99mTc]TBI reflects regional myocardial blood flow accurately in ischemic and normal resting myocardium and underestimates blood flow at high flows. The rate of myocardial redistribution after reperfusion is similar for [99mTc]TBI and 201TI.     

Synthesis and evaluation of a series of 99mTc(CO)3+ lisinopril complexes for in vivo imaging of angiotensin-converting enzyme expression.

In animal models of cardiac disease and in human congestive heart failure, expression of angiotensin-converting enzyme (ACE) is upregulated in the failing heart and has been associated with disease progression leading to cardiac failure and fibrosis. To develop probes for imaging ACE expression, a series of di(2-pyridylmethyl)amine (D) chelates capable of binding M(CO)3+ (M = technetium, rhenium) was conjugated to lisinopril by acylation of the epsilon-amine of the lysine residue with a series of di(2-pyridylmethylamino)alkanoic acids where the distance of the chelator from the lisinopril core was investigated by varying the number of methylene spacer groups to produce di(2-pyridylmethyl)amine(Cx)lisinopril analogs: D(C4)lisinopril, D(C5)lisinopril, and D(C8)lisinopril. The inhibitory activity of each rhenium complex was evaluated in vitro against purified rabbit lung ACE and was shown to vary directly with the length of the methylene spacer: Re[D(C8)lisinopril], inhibitory concentration of 50% (IC50) = 3 nM; Re[D(C5)lisinopril], IC50 = 144 nM; and Re[D(C4)lisinopril], IC50 = 1,146 nM, as compared with lisinopril, IC50 = 4 nM. The in vivo specificity for ACE was determined by examining the biodistribution of the 99mTc-[D(C8)lisinopril] analog in rats with and without pretreatment with unlabeled lisinopril. Uptake in the lungs, a tissue that constitutively expresses ACE, was 15.2 percentage injected dose per gram at 10 min after injection and was dramatically reduced by pretreatment with lisinopril, supporting ACE-mediated binding in vivo. Planar anterior imaging analysis of 99mTc-[D(C8)lisinopril] corroborated these data. Thus, high-affinity 99mTc-labeled ACE inhibitor has been designed with potency similar to that of lisinopril and has been demonstrated to specifically localize to tissues that express ACE in vivo. This agent may be useful in monitoring ACE as a function of disease progression in relevant diseases such as heart failure.