Double tracer autoradiography of bone tumor using 3H-thymidine and radionuclides for diagnostic purpose

Whole body distribution and accumulation of radionuclide for diagnostic purpose such as 99mTc-MDP (methylene diphosphonate), 67Ga-citrate (67Ga) and 201Tl-chloride (201Tl) in implanted osteosarcoma of human origin were evaluated by macroautoradiography of Balb/c nude mouse. 3H-thymidine of which uptake has a close relation to growth pattern of tumors was used for a partner of target nuclide in double tracer technique to examine the distribution characteristics. Separated distribution pattern of coupled nuclides was imaged by a difference both of half life and energy of radiation between radionuclides. The distribution pattern of each target nuclide and 3H-thymidine were compared to clarify distribution characteristics respectively in specimen. 67Ga and 201Tl were taken around the tumor and the mode of their distribution was identical to that of 3H-thymidine. Uptake of 67Ga in tumor was much higher. 99mTc-MDP accumulated in the central zone of the tumor and its pattern was quite different from that of 3H-thymidine. From above result it was demonstrated that the accumulation mechanism of 67Ga, 201Tl and 99mTc-MDP are quite different in the tumor each other. So we concluded that our method of double tracer technique was useful for evaluation of distribution pattern of radionuclides for diagnostic purpose.     

三羰基锝配体基苯基甲磺酰胺的合成与表征

以2-氨基-5-硝基苯酚为原料经过酚羟基烷基化、氨基甲磺酰化、硝基还原为氨基后,进行溴乙酰化以及N-烷基化5步反应制得了三羰基锝标记配体基：N-[2-环己基甲氧基-4(1-(2,2′-二吡啶甲基)胺基)乙酰胺基]苯基甲磺酰胺(NSC-PA),并对反应条件进行了优化。 中间体及目标化合物经红外、质谱和核磁共振氢谱进行了结构表征,HPLC法测定最终产物的纯度大于98%。 该目标化合物可以作为三羰基锝标记前体,为进一步开发乳腺癌显像药物奠定了基础。     

Preparation and biological evaluation of the new chlorin photosensitizer T3,4BCPC for detection and treatment of tumors

The new water-soluble photosensitizer 5,10,15,20-tetrakis[3,4-bis(carboxymethyleneoxy)phenyl]chlorin (T3,4BCPC) has been prepared, characterized and labeled with 99mTc radionuclide. The radiotracer was evaluated for tissue distribution in Wistar rats. Accumulation of administrated activities in the liver, kidney, bladder and large intestine at 4 h post-injection indicated that the labeled ligand was largely eliminated through the renal and partly through the hepatobiliary system. In vivo biodistribution studies of the labeled compound were carried out in rodent and murine tumor models in comparison with other tumor-seeking radiopharmaceuticals such as 99mTc(V)-dimercaptosuccinic acid (DMSA), 201thallous chloride (TlCl) and 99mTc-citrate using a gamma camera computer system. In N-nitrosomethylurea (NMU)-induced rat mammary tumors, the labeled ligand showed a five-fold tumor to muscle (T/M) ratio compared to 99mTc(V)-DMSA (3-fold) and 201TlCl (3-fold). In the case of C(3)H/J virus-induced spontaneous mammary tumors, the differences were not marked. However, in the transplanted rat C(6)-glioma, the T/M ratio of the labeled compound was appreciably higher (four-fold) than that noted with 99mTc(V)-DMSA (two-fold), 201TlCl (three-fold) and 99mTc-citrate (more than three-fold). These findings suggest that the radiolabeled T3,4BCPC may have potential for the detection of cancer. In order to ascertain the efficacy of the compound for photodynamic therapy applications, a preclinical PDT study was carried out in fibrosarcoma-bearing mice after injecting 5.0 mg/kg body weight of the T3,4BCPC. A laser dose of 20 mW for 60 s resulted in 80% destruction of tumors. These data suggest that this molecule could be useful for PDT of cancer. The labeled agent could also be useful in monitoring the progression/regression of tumors before, during, and after chemotherapy, radiation therapy or PDT.     

Biological evaluation and SPECT imaging of tumor hypoxia using a novel technetium-99m labeled tracer with 2-nitroimidazole moiety

Journal of Radioanalytical and Nuclear Chemistry - To develop novel 99mTc labeled nitroimidazole imaging agents for imaging tumor hypoxia, 99mTc labeled ethylene diamine tetraacetic acid derivative...     

一种新的潜在心肌显像剂[99mTc(CO)3(TBI)3]+的制备及其生物分布研究

以[99mTcO4]-为起始物,在0.1MPa下制备了中间体[99mTc(CO)3(H2O)1]+,通过配体交换反应,叔丁基异腈(TBI)配体取代该配合物中的3个水分子,制得一种标记率大于90%的[99mTc(CO)1(TBI)1]+配合物.该配合物在室温下放置6h以上,标记率无明显变化.在正常昆明小鼠体内的生物分布实验结果表明,[99mTc(CO)3(TBI)3]+具有较高的心肌摄取,且滞留也相当好,在静脉注射5min和60min后时的心肌摄取值分别为(19.07±0.81)%(ID/g)和(18.24±2.41)%(ID/g).该配合物的非靶本底摄取较低,注射60min后的心/肝、心/肺和心/血摄取比值分别为1.02,5.83和23.69,有望发展为一种新的心肌显像剂.     

Attenuation correction of SPECT imaging by dual energy method--quantification of 111In-labeled monoclonal anti-tumor antibody localization

Application of radiolabeled monoclonal anti-tumor antibodies for diagnosis and therapy has made remarkable progress in the past few years. Quantification of radiopharmaceutical localization is required adequate attenuation correction in SPECT imaging. Attenuation correction by transmission CT (TCT) data is one of the best method at present time. However, if a patient is moved between TCT and SPECT, this method is no more applicable. We developed a new attenuation correction algorithm by dual energy method, using 99mTc and 111In because of similarity of these linear attenuation coefficients. The new algorithm uses data of TCT with an external source of 99mTc, and requires another data from SPECT of 111In labeled monoclonal anti-tumor antibody, which are simultaneously obtained. TCT results in an attenuation map, which then serves as input into the final intrinsic correction algorithm to uncorrected SPECT data. In chest phantom experiment, the attenuation corrected SPECT images revealed nearly same distribution of actual radioactivity of 111In as compared to that of uncorrected one.     

Streamlined in vivo selection and screening of human prostate carcinoma avid phage particles for development of peptide based in vivo tumor imaging agents

Bacteriophage (phage) display has been exploited for the purpose of discovering new cancer specific targeting peptides. However, this approach has resulted in only a small number of tumor targeting peptides useful as in vivo imaging agents. We hypothesize that in vivo screening for tumor uptake of fluorescently tagged phage particles displaying multiple copies of an in vivo selected tumor targeting peptide will expedite the development of peptide based imaging agents. In this study, both in vivo selection and in vivo screening of phage displaying foreign peptides were utilized to best predict peptides with the pharmacokinetic properties necessary for translation into efficacious in vivo imaging agents. An in vivo selection of phage display libraries was performed in SCID mice bearing human PC-3 prostate carcinoma tumors. Eight randomly selected phage clones and four control phage clones were fluorescently labeled with AlexaFluor 680 for subsequent in vivo screening and analyses. The corresponding peptides of six of these phage clones were tested as 111In-labeled peptide conjugates for single photon emission computed tomography (SPECT) imaging of PC-3 prostate carcinomas. Two peptide sequences, G1 and H5, were successful as in vivo imaging agents. The affinities of G1 and H5 peptides for cultured PC-3 cells were then analyzed via cell flow cytometry resulting in Kd values of 1.8 μM and 2.2 μM, respectively. The peptides bound preferentially to prostate tumor cell lines compared to that of other carcinoma and normal cell lines, and H5 appeared to possess cytotoxic properties. This study demonstrates the value of in vivo screening of fluorescently labeled phage for the prediction of the efficacy of the corresponding 111In-labeled synthetic peptide as an in vivo SPECT tumor imaging agent.     

Determination of low-energy beta-emitter radionuclides deposited on surfaces by attapulgite treatment

A method for the determination of surface contamination of various materials by 3H and 99Tc is reported. Both 3H and 99Tcm are widely used in chemical and clinical applications. The isotopes 99Tc, the decay product of 99Tcm, and 3H are soft beta-emitter radionuclides and the use of unsealed sources can frequently produce contamination and excessive internal dosing for workers. The removal of radionuclides from surfaces was effected with attapulgite, a clay with a high absorption capacity for many organic and inorganic substances. The determination was carried out by extracting the absorbed radionuclide from the clay and then measuring it in a beta-scintillation counter. The determination limits of the method, 20 Bq cm-2 for 3H and 100 Bq cm-2 for 99Tc, are below the "derived working limits" for these radionuclides.     

Aqueous fluoride and the preparation of [99mTc(CO)3(OH2)3]+ and 99mTc-carborane complexes

A method for the preparation of eta5-metallocarborane complexes of technetium-99m in water was developed. The key to the procedure is the use of aqueous sodium or potassium fluoride, which prevents premature degradation of the Tc(I) starting material used to prepare the carborane complexes. Solid-phase extraction was used to purify Tc-metallocarboranes derived from both ortho and meta isomers, which were isolated in good to excellent yields in high radiochemical purities. In conjunction with these studies, a series of fluoride-based "kits" were developed to produce the key precursor [99mTc(CO)3(H2O)3]+ in the absence of any other stabilizing ligand. Using this approach, [99mTc(CO)3(H2O)3]+ could be prepared directly from 99mTcO4- under a range of pH values, including neutral pH, which affords the opportunity to develop one-pot labeling procedures for base-sensitive targeting vectors.     

High performance liquid chromatography of 99mTc labeled human serum albumin using an N-methylpyridinium polymer column.

Human serum albumin (HSA) labeled with 99mTc (99mTc-HSA) was analyzed by high performance liquid chromatography using a 4-vinylpyridinium polymer column which specifically resolved albumin components such as human mercaptalbumin (HMA), human non-mercaptalbumins (HNA), etc. The 99mTc-HSA radiochromatogram revealed that 99mTc-HSA consisted of several components. The radiochromatographic profile was similar to that of 99mTc-HMA prepared with 99mTc and separated HMA. This suggested that HMA participated mainly in 99mTc-labeling of HSA. When HSA was labeled with a stoichiometric concentration of 99Tc, the HMA peak was significantly decreased and new peaks were revealed by absorbance at 280 nm. From these results, the role of HMA in labeling HSA with 99mTc was elucidated.     

Tc标记的叶酸肿瘤显像剂

叶酸受体在许多源于上皮组织的恶性肿瘤中高度表达,是目前肿瘤放射性显像研究的一个新的靶点。由于叶酸对于叶酸受体具有很高的亲和性,作为重要的特异性靶向介导分子,^99mTc标记叶酸肿瘤显像剂已成为当前放射性药物的研究热点之一。本文对不同类型的^99mTc标记的叶酸类放射性肿瘤显像剂的研究进展、应用情况和存在的问题进行了评述,探讨了^99mTc标记叶酸显像剂的一般设计方法,并对其未来发展方向进行了展望。     

Novel 99mTc labeled σ receptor ligand as a potential tumor imaging agent

A novel 99mTc labeled complex, [N-[2-((2-oxo-2-(4-(3-phenylpropyl)piperazin-1-yl)ethyl) (2-mercaptoethyl)amino)acetyl]-2-aminoethanethiolato]Technetium(V) oxide (PPPE-MAMA′-99mTcO) ([99mTc]-2) has been designed and prepared based on the integrated approach. The corresponding rhenium complex (PPPE-MAMA′-ReO)(Re-2) has been prepared and characterized. In vitro competition binding assays show moderate affinity of Re-2 towards σ1 and σ2 receptors with Ki values of 8.67 ± 0.07 and 5.71 ± 1.88 μmol, respectively. Planar images obtained at 0.5 h, 4 h, 20 h after I.v. Injection indicate the accumulation of [99mTc]-2 in MCF-7 human breast tumor bearing mice at 20 h. Furthermore, the accumulation of [99mTc]-2 has been inhibited at 20 h after co-injection of [99mTc]-2 plus haloperidol (1 mg/kg). Biodistribution studies of [99mTc]-2 display an in vivo tumor uptake of 0.14% ± 0.01% ID/g at 24 h post I.v. Injection with a tumor/muscle ratio of 6.02 ± 0.87. The above results suggest that [99mTc]-2, derived from a previously published lead compound, retains certain tumor uptake and affinity for σ receptors. [99mTc]-2 may be used as a basis for further structural modifications to develop tumor imaging agents with high affinity for σ receptors.     

Impact of Different [Tc(N)PNP]-Scaffolds on the Biological Properties of the Small cRGDfK Peptide: Synthesis,In Vitro and In Vivo Evaluations

Background: The [^99mTc][Tc(N)(PNP)] system, where PNP is a bisphosphinoamine, is an interesting platform for the development of tumor ‘receptor-specific’ agents. Here, we compared the reactivity and impact of three [Tc(N)(PNP)] frameworks on the stability, receptor targeting properties, biodistribution, and metabolism of the corresponding [^99mTc][Tc(N)(PNP)]-tagged cRGDfK peptide to determine the best performing agent and to select the framework useful for the preparation of [^99mTc][Tc(N)(PNP)]-housing molecular targeting agents. Methods: cRGDfK pentapeptide was conjugated to Cys and labeled with each [Tc(N)(PNP)] framework. Radioconjugates were assessed for their lipophilicity, stability, in vitro and in vivo targeting properties, and performance. Results: All compounds were equally synthetically accessible and easy to purify (RCY ≥ 95%). The main influences of the synthon on the targeting peptide were observed in in vitro cell binding and in vivo. Conclusions: The variation in the substituents on the phosphorus atoms of the PNP enables a fine tuning of the biological features of the radioconjugates. ws[^99mTc][Tc(N)(PNP3OH)]– and [^99mTc][Tc(N)(PNP3)]– are better performing synthons in terms of labeling efficiency and in vivo performance than the [^99mTc][Tc(N)(PNP43)] framework and are therefore more suitable for further radiopharmaceutical purposes. Furthermore, the good labeling properties of the ws[^99mTc][Tc(N)(PNP3OH)]– framework can be exploited to extend this technology to the labeling of temperature-sensitive biomolecules suitable for SPECT imaging.     

Water-soluble derivatives of chitosan as a target delivery system of <Superscript>99m</Superscript>Tc to some organs in vivo for nuclear imaging and biodistribution

Carboxymethyl chitosan, (CMC), and N-lauryl-carboxymethyl chitosan (LCMC), have been prepared as water soluble derivatives of chitosan. These biodegradable chitosan derivatives were characterized and investigated for nuclear imaging and body distribution. They were labeled with ^99mTc to use them as targeted delivery to some organs in vivo for nuclear imaging and to follow their biodistribution within the body. The factors controlling the labeling efficiency have been investigated. The percent labeling yield was determined by using ascending paper chromatographic technique. In vivo biodistribution studies of radiolabeled chitosan derivatives were carried out in groups of female Wistar rats, the body distribution profile in rat was recorded by gamma scintigraphy and the biodistribution of ^99mTc-labeled compounds in each organ was calculated as a percentage of the injected dose per gram of tissue (%ID/g). It has been found that the biodistribution of the two compounds and the pattern of their liver uptake were markedly different. The present study demonstrates a high potential approach for liver imaging using ^99mTc-LCMC. An intriguing finding of this study was that the three samples were excreted rapidly via the kidneys because of the water-soluble nature of chitosan derivatives. This suggests that water-soluble chitosan derivatives are good polymeric carriers for radioactive element that overcomes accumulation in the body. Moreover, the easy and inexpensive availability of chitosan could be beneficial for applications in scintigraphic imaging.     

99mTc-AMD3100: A novel potential receptor-targeting radiopharmaceutical for tumor imaging

<正>The chemokine CXCR4 receptor is over-expressed in a wide variety of tumors.In this study,AMD3100,which was a prototype non-peptide antagonist of CXCR4 receptor,was labeled with ~(99m)Tc.~(99m)Tc-AMD3100 was verified by thin layer radio chromatography(TLRC).The tumor-localizing properties of ~(99m)Tc-AMD3100 were evaluated and proved in mice bearing Hep-G2 tumor xenograft.~(99m)Tc-AMD3100 was a promising,novel receptor-specific radiopharmaceutical with potential application in the imaging of human tumors.     

Improved Stabilities of Labeling Probes for the Selective Modification of Endogenous Proteins in Living Cells and In Vivo

To date, various affinity-based protein labeling probes have been developed and applied in biological research to modify endogenous proteins in cell lysates and on the cell surface. However, the reactive groups on the labeling probes are also the cause of probe instability and nonselective labeling in a more complex environment, e. g., intracellular and in vivo. Here, we show that labeling probes composed of a sterically stabilized difluorophenyl pivalate can achieve efficient and selective labeling of endogenous proteins on the cell surface, inside living cells and in vivo. As compared with the existing protein labeling probes, probes with the difluorophenyl pivalate exhibit several advantages, including long-term stability in stock solutions, resistance to enzymatic hydrolysis and can be customized easily with diverse fluorophores and protein ligands. With this probe design, endogenous hypoxia biomarker in living cells and nude mice were successfully labeled and validated by in vivo, ex vivo, and immunohistochemistry imaging.     

Biosorption of 241Am by immobilized Saccharomyces cerevisiae

More than half of the world's annual production of radionuclides is used for medical purposes such as diagnostic imaging of diseases and patient therapy. Using aqueous homogeneous solution reactor technology, production quantities of medical radioisotopes ⁹⁹Mo and⁸⁹Sr, can be extracted from one reactor cycle. ⁹⁹Mo may be produced directly from UO₂SO₄ uranyl sulfate in an aqueous homogeneous solution nuclear reactor in a manner that produces high purity radionuclides, making efficient use of the reactor's uranium fuel solution. The process is relatively simple, economical, and waste free, eliminating uranium targets. The short-lived radioisotope ^99mTc is eluted from ⁹⁹Mo for diagnostic imaging. Radioisotope ⁸⁹Sr infusion is a therapeutic modality that reduces reliance on narcotic analgesia through palliation of metastatic bone pain caused by metastases of the cancer to the bone. Painful disseminated osseous metastases are common with carcinomas of the lung, prostate, and breast. Synergistic interleaving of two manufacturing processes, one producing ⁹⁹Mo and another producing ⁸⁹Sr in the same production cycle of an aqueous homogeneous solution reactor makes full and efficient use of the time for both the neutron irradiation stage and the extraction stage of each radionuclide. Interleaving the capture of ⁸⁹Sr radioisotope with production processing of ⁹⁹Mo radioisotope is achieved, since the extraction and subsequent elimination of radionuclide impurities occurs during separate parts of the reactor cycle. The process applies to either HEU or LEU nuclear fuels in an aqueous homogeneous solution reactor.     

Linkage effects on binding affinity and activation of GPR30 and estrogen receptors ERalpha/beta with tridentate pyridin-2-yl hydrazine tricarbonyl-Re/(99m)Tc(I) chelates

We describe a new structural class of neutral tridentate pyridin-2-yl hydrazine chelates for labeling with tricarbonyl Re/99mTc(I) under aqueous conditions and investigate the receptor binding of synthetic estradiol derivatives with the novel G-protein-coupled receptor GPR30 and estrogen receptors ERalpha/beta. The steroid linkage affected the affinity and selectivity of estrogen binding with these receptors. Fluorescence assays based on calcium signaling demonstrate that membrane-permeable chelates 2 and 3 interact with the receptors in whole cells. These results suggest that in vitro assays will facilitate the development of targeted imaging agents for intracellular receptors and the feasibility of targeting GPR30 and ERalpha/beta for diagnostic tumor imaging.     

Preparation of (99m)Tc labeled vitamin C (ascorbic acid) and biodistribution in rats

The aim of this study was to label ascorbic acid with (99m)Tc and to investigate its radiopharmaceutical potential in rats. Ascorbic acid was labeled with (99m)Tc using the stannous chloride method. The radiochemical purity of [(99m)Tc]ascorbic acid ((99m)Tc-AA) was determined by RTLC, paper electrophoresis, and RHPLC methods. The labeling yield was found to be 93+/-5.0%. The maximum labeling yield of (99m)Tc-AA was determined at pH 5 and 25 degrees C. The biodistribution studies related to (99m)Tc-AA were done in male albino Wistar rats. (99m)Tc-AA, which has a specific activity of 13.02 GBq/mmol, was administered into the tail vein of the rats. The rats were sacrificed at 15, 30, 60, and 120 min after the injection by heart puncture under ether anaesthesia. The organs were weighed after removal. Their activities were counted using a Cd(Te) detector equipped with a RAD 501 count system. The %ID/g (% of injected dose per gram of tissue weight) in each organ and in blood was calculated. Maximum uptake of (99m)Tc-AA was observed in prostate and kidneys at the 60th min. (99m)Tc-AA may be a promising radiopharmaceutical for the imaging of prostate and kidneys.     

Liposomes prepared from synthetic amphiphiles. I. Their technetium labeling and stability

In order to apply liposomes prepared from synthetic amphiphiles containing amino acid residues to radiopharmaceuticals, their labeling with 99Tc or 99mTc and stability in saline or in serum were investigated. These liposomes were highly labeled by embedding stearylamine-diethylenetriamine pentaacetic acid as a ligand of technetium. The labeling was more efficient at pH 7.0 than at pH 4.0 or 8.5. Among these technetium-labeled liposomes tested, liposomes containing the alanine residue were stable in saline or in 50% serum at 37 degrees C for at least 24 h, in contrast to liposomes (phosphatidylcholine: cholesterol = 1:1 molar ratio) whose stability had been enhanced by adding cholesterol.