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The highly bidirectional dialogue between the gut and the brain is markedly stimulated and influenced by the microbiome through integrated neuroendocrine, neurological and immunological processes. Gut microbiota itself communicate with the host producing hormonal intermediates, metabolites, proteins, and toxins responsible for a variety of biochemical and functional inputs, thereby shaping host homeostasis. Indeed, a dysregulated microbiota-gut-brain axis might be the origin of many neuroimmune-mediated disorders, e.g. autism, multiple sclerosis, depression, Alzheimer's and Parkinson's disease, which appear months or even years prior to a diagnosis, corroborating the theory that the pathological process is spread from the gut to the brain. A much deeper comprehension of how commensal microbe can be manipulated to interfere with disease progression is crucial for developing new strategies to diagnose and treat diseases. In recent years, the potential of positron-emission-tomography (PET) in the field of bacteria detection has gained attention. The uptake of several PET tracers has been evaluated to investigate infection pathophysiology, e.g. sterile or pathogen-mediated infection, monitoring of progression, or as a surrogate endpoint in clinical trials. In this minireview, we briefly describe the role of microbiome-gut-brain axis in health and disease and we discuss the imaging modalities and agents that could be applied to study the dynamic interactions between microbiome, gut and brain. These are key aspects in understanding the biochemical lexicon underpinning the microbiome-host crosstalk that would enable the development of diagnostics and therapeutics by targeting the human microbiota.

The transmetallation reaction between zinc dithiocarbamates and rhenium carbonyls has been used as a new strategy to link biomolecules to transition metals. The zinc(II) dithiocarbamate of isonipecotic acid (1) and the succinimidyl ester derivative (2) were prepared by straight forward procedures and were fully characterized by spectroscopic and X-ray diffraction methods, showing in both cases the presence of dinuclear complexes. Complex 2 reacted with all the primary and secondary amines studied (glycine methyl ester, β-alanine methyl ester, 1-(2-methoxyphenyl)piperazine and D-(+)-glucosamine) through the activated succinimidyl ester group, linking the metallic fragment with the biomolecule by the formation of a peptidic bond, and leading to the respective bioconjugated zinc complexes 3-6. In all cases, these zinc complexes could be isolated from the reaction medium by simple precipitation. These results evidence the potential of complex 2 to be used as a synthon to link the zinc dithiocarbamate fragment to biomolecules that contain an amine group. Complexes 3-6 were characterized by the usual spectroscopic methods and all data agree with the proposed structures, which do not contain significant interactions between the zinc fragment and the functional groups of these biomolecules. The transmetallation reaction between the zinc complexes 3-6 and the rhenium carbonyl [ReBr₃(CO)₃]²⁻ led to the expected rhenium dithiocarbamates 7-10 with no change in the organic dithiocarbamate fragments, confirming the viability of this reaction as a tool for linking biomolecules to transition elements. All complexes were characterized by spectroscopic methods and the crystal structure of 8 was studied by X-ray diffraction analysis. All data demonstrated that the biomolecule is positioned far away from the fac-{Re(CO)₃} fragment and the octahedral coordination around the metal is completed by the functionalized dithiocarbamate and a phosphine ligand. Finally, the analysis by ESI-MS spectrometry of the reaction between the zinc complex 4 and a water solution of [Re(H₂O)₃(CO)₃]+ at a very low concentration (10 ppm) showed that the transmetallation reaction took place even though the solubility of the zinc complex in water medium was as low as 0.66 ppm. This preliminary result supports the viability of this approach for the preparation of rhenium and technetium target specific radiopharmaceuticals since the preparation of these compounds are always performed in water medium.

Objective The in-use stability of lyophilised oxaliplatin and lactose formulation diluted in 5% dextrose injection was studied to assess the feasibility of preparing oxaliplatin solutions in advance in hospital pharmacy settings. The available in-use stability data of oxaliplatin solutions are based on infusions prepared with 5 mg/mL concentrated solutions. Methods Oxaliplatin solutions of 0.5 mg/mL (n=6), 0.7 mg/mL (n=6) and 5 mg/mL (n=6) were prepared using oxaliplatin 100 mg powder and 100 mL of 5% dextrose injection in polyolefin infusion bags. The samples were stored at 2–8°C without light protection and were analysed at 1, 2, 4, 7, 14, 21 and 60 days. The in-use stability was studied using the high-performance liquid chromatography stability indicating method. The solutions were checked for colour, particulate matter and pH. Results The mean concentrations of 0.5 mg/mL and 0.7 mg/mL oxaliplatin solutions decreased to less than 90%, within 7 and 14 days, respectively, compared with the initial drug concentration in the solutions. The concentrated solution of 5 mg/mL oxaliplatin was stable (over 90%) for at least 60 days. The colour, clarity and pH remained unchanged throughout the storage period. Sterility and apirogenicity standards, as defined in the European Pharmacopoeia, were met. Conclusion Infusion solutions of oxaliplatin prepared with lyophilised oxaliplatin 100 mg, 0.5 mg/mL and 0.7 mg/mL which were stored in polyolefin infusion bags, were chemically unstable within 7 days and 14 days, respectively, at 2–8°C without light protection. The poor stability of the diluted solutions does not allow oxaliplatin to be prepared in advance and stored in pharmacy departments.

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical. Methods 188 Re-HA was prepared by a direct labelling method to produce a ReO(O-COO) 2 -type coordination complex. 188 Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice ( n =60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of 188 Re-HA was determined. Results A stable complex of 188 Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance ( T 1/2 α=21 min). Four hours after administration, 188 Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47±5.11% of the injected dose). The liver MTD in mice was ∼40 Gy after 7.4 MBq of 188 Re-HA injection. Conclusions 188 Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.

The antimicrobial peptide ubiquicidin (UBI) directly labeled with technetium-99m ( 99m Tc) has recently been shown to be specifically taken up at sites of infection; however, its chemical structure is not well defined. To address this problem, the aim of the present study was to label UBI using poly(ethyleneglycol)– N -( N -(3-diphenylphosphinopropionyl)glycyl)- S -tritylcysteine ligand (PEG-PN 2 S) in order to compare its ability to detect infection sites with that of 99m Tc-UBI. Methods The PN 2 S-PEG-UBI conjugate was prepared and labeled with 99m Tc, and its radiochemical purity was subsequently assessed. The stability of the conjugate to cysteine challenge and dilution with both saline solution and phosphate buffer was determined and serum stability and protein binding were also assessed. In vivo studies were carried out in healthy mice to study the biodistribution of 99m Tc-PN 2 S-PEG-UBI and its precursor 99m Tc-PN 2 S-PEG and in infected mice to compare the uptakes of 99m Tc-UBI and 99m Tc-PN 2 S-PEG-UBI at the site of infection using scintigraphic imaging and ex vivo tissue counting. Results 99m Tc-PN 2 S-PEG-UBI was obtained with high radiochemical purity (98±1%) and high stability. The amphiphilic nature of the conjugate leads to a tendency to form micellar aggregates that explain the high protein binding values obtained. Biodistribution studies in mice showed low renal clearance followed by a predominant reticuloendothelial system clearance that limits its application in the abdominal area. Statistical analysis revealed no significant difference between 99m Tc-UBI and 99m Tc-PN 2 S-PEG-UBI uptake in infected mouse thigh, and the site of infection was clearly visualized using scintigraphic imaging. Conclusions 99m Tc-PN 2 S-PEG-UBI proved to be as effective as 99m Tc-UBI in detecting sites of infection; however, the well-defined chemical structure of 99m Tc-PN 2 S-PEG-UBI makes it a better candidate for clinical imaging of infection.

The synthesis, the characterization and the X-ray crystal structure of a novel tantalum(v) complex tris(1,2-dimethyl-3-hydroxy-4(1H)-pyridone)oxotantalum(v) [TaO(C7H8O2N)3] 1 is reported. Starting from the tantalum pentaethoxide a two-step reaction was carried out observing rigorous anhydrous conditions in methanol in the first step, while the insertion of the oxo group was achieved using water as oxygen donor in the second step. X-Ray diffraction analysis of a crystal of 1 obtained upon evaporation of an aqueous solution shows a seven-coordinate monomeric complex containing the [Ta=O]3+ core in the triclinic space group P1, a = 7.282(3), b = 14.055(5), c = 16.987(6) A, alpha = 65.704(5), beta = 89.155(6), gamma = 75.270(6) degrees, V = 1525(1)A3, Z = 2. Spectroscopic investigation reveals that the complex is highly soluble and stable in water at physiological pH values; as a consequence the complex may represent a potential candidate for the development of new studies on aqueous tantalum(v) chemistry for radiopharmaceutical applications.

Paclitaxel, an anti-tumour drug, shows good results against breast and ovarian cancer. However, its therapeutic response is associated with toxic side-effects caused by the agent used to dissolve it. Recently paclitaxel was linked to the linear polysaccharide hyaluronic acid (HA), showing good solubility, stabilization, localization and a reduction of cytotoxic side-effects. To study potential therapeutic applications, HA-paclitaxel bioconjugate (ONCOFID-P) was labelled with 99mTc by the addition of 99mTc-pertechnetate, SnCl2 and sodium gluconate. The reaction mixture was incubated for 90 min at 65°C and purified by size exclusion chromatography. The obtained 99mTc-ONCOFID-P had 100% radiochemical purity and was stable in a phosphate buffer dilution 1:100 for 6 h at 37°C. 99mTc-ONCOFID-P bioavailability studies were carried out in healthy mice using four different administration pathways. The analysis showed that after intravenous administration more than 80% of the injected radiopharmaceutical was found in liver and spleen. Intraperitoneal, intravesical and oral administrations showed that all the 99mTc-ONCOFID-P remained at the administration site. These results demonstrate that ONCOFID-P administered intravenously could be used for liver metastasis therapy due to its high physiological and receptor-specific liver uptake, while intravesical, intraperitoneal and oral administration of ONCOFID-P could be used for local treatment of superficial cancers. Copyright © 2006 John Wiley & Sons, Ltd.

A new (SS)(P) coordination set based on the concurrent use of a dithiocarbamate and a functionalised phosphane is reported. The (SS)(P) fashion is achieved by applying the [2+1] mixed-ligand concept and makes it possible to obtain stable rhenium tricarbonyl complexes without employing tripodal bifunctional chelating agents (BFCAs). The coordination chemistry of the simple sodium N,N-dimethyldithiocarbamate and new functionalised phosphanes L1–L3 [L1 = Ph2PCH2CH2C(O)OCH3, L2 = Ph2PCH2CH2C(O)NHCH2C(O)OCH3, L3 = Ph2PCH2CH2C(O)NHCH2CH2C(O)OCH3] was studied by reaction with the rhenium complex [NEt4]2[fac-Re(CO3)Br3]. The rhenium tricarbonyl core was found to be stabilised by the SS chelation of dithiocarbamate and by the P coordination of the phosphane. Two synthetic pathways leading to the complexes [fac-Re(CO)3(L)(MDTC)] (L = L1, L2, L3; MDTC = N,N-dimethyldithiocarbamate) are described. The structural characterisation of the isolated complexes by spectroscopic methods is reported, including X-ray crystallographic analysis for rhenium complexes with ligands L1 and L3. The homologous Tc-99m compounds with the same (SS)(P) coordination set were prepared at tracer level with the L2 and L3 ligands, and characterised by HPLC methods. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

N-[N-(3-diphenylphosphinopropionyl)glycyl]cysteine and its methyl ester derivative were labeled with (99m)Tc at neutral pH, leading to a single species in high yield (>95%) in 30 min. RP-HPLC comparison with the analogue Re(V)-oxo complexes identified the labeled compounds as the anti isomers of pentacoordinated (99m)TcO[PN(2)S]-OH and (99m)TcO[PN(2)S]-OMe complexes. The compounds are stable from pH 7 to pH 9 when (99m)TcO[PN(2)S]-OH interconverts to related syn isomer, while (99m)TcO[PN(2)S]-OMe undergoes both saponification and interconversion. They exhibit high stability in human plasma and in vivo (mice), and a biodistribution characterized by hepatobiliary excretion.

New rhenium and technetium-99m complexes with the monodentate thiol HSCH2CH2SO3Na (coenzyme M, MESNA) have been prepared for radiopharmaceutical purposes. Using the ‘3 + 1’ approach, the anionic rhenium complex [ReO(SCH2CH2SCH2CH2S)(SCH2CH2SO3)]− was prepared in two different ways: (1) reaction of MESNA with the complex [ReO(SCH2CH2SCH2CH2S)Cl]; and (2) reaction of the tridentate ligand S(CH2CH2SH)2 with the MESNA complex [ReO(SCH2CH2SO3Na)4]−. The structure of this ‘3 + 1’ complex was determined by X-ray crystallographic studies, showing the characteristic {ReOS4} coordination around the metal atom. The sulfonate group of the coordinated MESNA is located far from the rhenium metal and near to the sodium cations. Chromatographic analysis of the reaction products after subsequent addition of MESNA and the tridentate ligand to the 99m-Tc gluconate precursor revealed the formation of a mixture of the ‘3 + 1’ technetium complex [99mTcO(SCH2CH2SCH2CH2S)(SCH2CH2SO3)]− and the complex with the monothiol [99mTcO(SCH2CH2SO3Na)4]−. The limited solubility of the ‘3 + 1’ rhenium complex in water may explain the high yield obtained in the rhenium synthesis compared with the lower yield observed in the same reaction with the homologous technetium-99m complexes.

This paper describes a simple and rapid procedure for the quantitation of the CCK-4 fragment of cholecystokinin by reversed phase high-performance liquid chromatography (RP-HPLC). The eluent for suitable separation on a C-18 column as stationary phase, was a water/acetonitrile (70/30, v/v) mixture with 0.05 trifluoroacetic acid, pH 2; UV detection was set at 280 nm. The method was developed and validated according to the International Conference on Harmonization (ICH) guidelines. The results obtained in the validation process, indicate that the method is specific, linear, accurate (recovery mean = 100.2±3.0%), and reliable (precision=1.21%). Limit of detection is established for 10.9 μg/mL and limit of quantitation for 33.1 μg/mL. In addition, the usefulness of the method, in order to evaluate the stability of the compound, was demonstrated.

A technetium-99m-labeled peptide derived from ubiquicidine, further referred to as 99mTc-UBI 29-41, targets bacterial and fungal infections, but not sterile inflammatory processes, in experimental animals. This paper reports on the radiochemical and biological features of this radioactive agent and the importance of the amino acid sequence of UBI 29-41 for imaging of infections. Radiochemical analyses of 99mTc-UBI 29-41 and a radiolabeled scrambled version of this peptide, i.e. 99mTc-Sc-UBI 29-41, revealed that both peptides were labeled rapidly (within 10 min) and effectively with little colloid formation (less than 5% of the total radioactivity) and very little free pertechnetate (or radioactive intermediates) in the preparations containing radiolabeled peptide. Furthermore, association of the peptides with bacteria could be competed with excess unlabeled peptide and this association proved to be temperature-dependent. Based on this in vitro data we concluded that labeling of peptides with 99mTc by this direct method is rapid, efficient, and safe. Scintigraphy demonstrated that radioactivity is rapidly removed from the circulation (half-lifes of UBI 29-41 and Sc-UBI 29-41 were 16 and 21 min, respectively) mainly by renal clearance. Analysis of murine blood revealed that only a small proportion of the intravenously injected 99mTc-peptides is associated with blood cells. Although both radiolabeled peptides accumulated rapidly at sites of infection, the values for 99mTc-UBI 29-41 were higher (P0.05) than for 99mTc-Sc-UBI 29-41. Moreover, injection of excess unlabeled UBI 29-41, but not Sc-UBI 29-41, into Staphylococcus aureus-infected mice prior to injection of 99mTc-UBI 29-41 significantly (P0.05) reduced the accumulation of this radiopharmaceutical at the site of infection. In addition, we observed significantly (P0.01) higher amounts of 99mTc-UBI 29-41 at the site of infection in mice using a carrier-free radiolabeled UBI 29-41 as compared with unpurified preparations containing radiolabeled UBI 29-41. This in vivo data indicates that the amino acid sequence of 99mTc-UBI 29-41 contributes to its accumulation at the site of infection.

99mTc-labeling studies have been performed on CCK(4) fragment of cholecystokinin, starting from 99mTc-pertechnetate, by using tin(II)pyrophosphate or tin(II)gluconate as reducing agents, together with NaBH(4) acting as a stabilizing agent of tin(II). Gluconate has been used as exchange ligand in the carrier added experiments and in the syntheses of 99Tc-CCK(4) and Re-CCK(4) complexes to be able to reproduce at macroscopic level the same chemical reactions occurring at non carrier added conditions. 99mTc-labeling yields higher than 95% have been achieved depending on Sn(II) concentration, CCK(4)/gluconate ratio, reaction time and applied temperature. The species produced with 99mTc, 99Tc, and cold rhenium nuclides have been compared by means of HPLC measurements, which showed similar retention times and thus probably the same species in the three situations.

A new phosphine derivatized peptide tetradentate ligand containing the PN2S donor atom set, 3- diphenylphosphinepropionylglycyl- l -(S- benzyl ) cysteinyl methyl ester, was synthesized in good yields by coupling a phosphine group to protected Gly- l -Cys dipeptide. Complexation of the new ligand with rhenium proceeded in satisfactory yields by substitution reaction on ReVOCl3(PPh3)2 in a 1.2:1 molar ratio. The resulting rhenium complex was characterized by IR, FAB-MS, 1H and 31P NMR spectroscopy and was found to be neutral and diamagnetic. These studies revealed, that rhenium (V) in a trans-ReOCl2+ cor coordinates with the PN2S2− donor atom set formed by one neutral phosphine, one neutral thioether and two deprotonated amide groups of the ligand forming a neutral complex. High performance liquid chromatography tests verified the purity and high stability of the complex in solution for long periods of time. In alkaline organic media the complex transforms to an equally stable, more hydrophilic analogue, in which the methyl ester group of cysteine is hydrolyzed to the free carboxylate.

PN2S coordinate around ReO3+ and TcO3+ cores producing TcO(PN2S) complexes with the ligand acting as tetradentate in the equatorial plane in respect to MO. Two isomers of PN2S-CO2Me have been evidentiated assuming sin-anti positions of the methyl ester group in respect to MO. Labelling experiments with 99mTcO4− and Sn(II)-gluconate, carried out in mild conditions, showed a single compound in high yields referred to the species 99mTcO(PN2S).

The synthesis of Re(I) and 99Tc(I) tricarbonyls complexes has been performed with a new phosphine containing tridentate chelator. Characterization of the complexes showed different coordinative patterns (POO, PNS and PO). All the obtained products were stable to substitution, confirming the phosphine containing peptides as ligands suitable to stabilize the M(CO)3+ moiety.

[Tc(C 13 Hi9NOS)(O)(C 6 H 5 S)] cristallise dans P2 1 avec a = 7,901, b = 10,147 et c = 11,370 A, β = 93,60 °, Z = 2; affinement jusqu'a R = 0,055. Le coordinat dianionique tridente s'etale sur trois positions dans le plan de base, incluant l'atome O phenolique, l'atome N neutre et l'atome S thiolate, la quatrieme position etant occupee par l'atome S du benzenethiolate.

Introduction: Gamma-ray detectors represent sensitive and noninvasive instruments to evaluate in vivo the metabolic trapping of radiopharmaceuticals. This study aimed to assess the imaging biodistribution of a [ 99m Tc]-radiolabelled new prototype bioconjugate composed of paclitaxel linked to hyaluronan (ONCOFID-P). Methods: A small gamma camera providing high-resolution images was employed. Imaging of biodistribution following intravenous, intraperitoneal, intravesical and oral administration was carried out for a 2-h period in anesthetized mice receiving [ 99m Tc]ONCOFID-P. At the end of the observation time, radioactivity in organs was directly measured. As a control, groups of mice were treated with free [ 3 H] paclitaxel given according to the same administration routes, and organ biodistribution of the drug was assessed after 2 h. Results: Intravenous inoculation of [ 99m Tc]ONCOFID-P was followed by a rapid and strong liver uptake. In fact, almost 80% of the imaging signal was detected in this organ 10 min after injection and such value remained constant thereafter, thus indicating that the bioconjugate given through the intravenous route could be well suited to targeting primary or metastatic liver neoplasias. Imaging of the bladder, abdomen and gastrointestinal tract after local administration disclosed that the radiolabelled compound remained confined to the cavities, suggesting a potential regional application for transitional bladder cell carcinomas, ovarian cancers and gastric tumors, respectively. Free [ 3 H]paclitaxel biodistribution profoundly differed from that of [ 99m Tc]ONCOFID-P. Conclusions: Conjugation of drugs with polymers results in new chemical entities characterized by a modified biodistribution pattern. Therefore, preclinical studies based on imaging analysis of such new compounds can suggest novel therapeutic applications.

Ligand-exchange reactions of the tetradentate unsaturated N2S2 Schiff-base ligand N,N'-ethylenebis-(thioacetylacetonylideneimine) (H2L) with labile monooxo-technetium(v) and -rhenium(v) compounds ([NBu4][TcOCl4]; [NBu4][ReOCl4] or [ReOCl3(PPh3)2]) gave two types of neutral six-co-ordinated species [MO(L)Cl] and [{MO(L)}2O] (M = Tc or Re). The monooxo monomeric complexes rearrange to the mu-oxo dimeric species via a charged labile intermediate in wet organic solvents or when solutions are kept in contact with air. Reaction of H2L with [NBu4][Tc(VI)NCl4] follows a reduction-substitution route to give another neutral, but five-co-ordinated species, [TcN(L)] which contains the [Tc(V) = N]2+ nitrido core. All complexes have been characterized by means of standard spectroscopic techniques. The influence of the metal on ligand H-1 NMR chemical shifts is discussed. The technetium centre shifts all the ligand protons more downfield than does rhenium. This behaviour is in general agreement with the stronger acidity of the [TcO]3+ core with respect to [ReO]3+. The five-co-ordination of the nitrido complex [TcN(L)] is confirmed by its X-ray structure determination: monoclinic, space group P2(1)/n, a = 14.654(7), b = 12.62(5), c = 7.819(4) angstrom, beta = 92.60(3)-degrees and Z = 4. The co-ordination sphere around the Tc centre is nearly square pyramidal with an apical multiply bonded nitrogen atom [Tc = N 1.621(8) angstrom].

Purpose: This study was designed to evaluate the pharmacologic and biological properties of a paclitaxel-hyaluronan bioconjugate (ONCOFID-P) against IGROV-1 and OVCAR-3 human ovarian cancer xenografts following i.p. administration. Experimental Design: In vitro tumor sensitivity to ONCOFID-P was analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, whereas bioconjugate interaction with cells was studied cytofluorimetrically and by confocal microscopy. In vivo toxicity was assessed by a single-dose maximum-tolerated dose, peripheral blood cell count determination and by histologic analysis. Biodistribution of the compound was evaluated with a small animal–dedicated scintigraphy gamma camera following injection of 99mTc-labeled ONCOFID-P. Pharmacokinetic analysis was also carried out. Female severe combined immunodeficiency mice implanted with ovarian cancer cells underwent treatment with ONCOFID-P or free paclitaxel starting from day 7 or 14 after tumor injection, and survivals were compared. Results: ONCOFID-P interacted with CD44, entered cells through a receptor-mediated mechanism, and exerted a concentration-dependent inhibitory effect against tumor cell growth. After i.p. administration, the bioconjugate distributed quite uniformly within the peritoneal cavity, was well-tolerated, and was not associated with local histologic toxicity. Pharmacokinetic studies revealed that blood levels of bioconjugate-derived paclitaxel were much higher and persisted longer than those obtained with the unconjugated free drug. Intraperitoneal treatment of tumor-bearing mice with the bioconjugate revealed that ONCOFID-P exerted a relevant increase in therapeutic activity compared with free drug. Conclusions: ONCOFID-P significantly improved results obtained with conventional paclitaxel, in terms of in vivo tolerability and therapeutic efficacy; these data strongly support its development for locoregional treatment of ovarian cancer.

Assessment of “in vitro” tumor growth inhibition and radiobiological effects, such as apoptosis, have been evaluated in human neoplastic cells of different histotypes (H460 lung cancer cells, U87 glioblastoma, LnCaP prostate tumor cells) treated using solutions of 188 Rhenium-perrhenate. The MTT assay, which measures mitochondrial metabolism in the entire cell culture is a recognized test for cytotoxicity and was used in cells exposed 48–72 h to specific activities ranged from 37 to 148 GBq/l. Whereas H460 and LnCaP were particularly sensitive to treatment, U87 glioblastoma cells behaved as radioresistant ones. However, evaluation of 188 Re-induced apoptosis indicated that this kind of cell death contributed only marginally to the reduction in cell viability of H460 and LNCaP lines, suggesting the existence of protective mechanisms against apoptosis. In this respect, the membrane receptor, CD44, whose expression is dysregulated in most malignant cell types has proven to alter the response of cancer cells to apoptotic stimuli, including ionizing radiation. Cell samples decorated with a FITC-labelled CD44 antibody indicated, that in H460 and U87 cells the CD44(+) correlated well with an apoptosis-resistant response. Conversely, LnCap cells proven as CD44(−) did not display however sensitivity to radio-induced apoptosis.

188 Re is a beta and gamma emitter used in metabolic radiotherapy. SCINTIRAD is a multidisciplinary collaboration that aims at determining the radio-response of 188 Re in cells “in vitro” and the biodistribution in different organs of mice “in vivo”, and studying the therapeutic effect on liver and other tumours induced in mice. Several tumour cell lines have been treated “in vitro” with a 188 Re solution. The dosimetry of 188 Re used to target the different lines of cancer cells has been evaluated using GEANT4, and preliminary results are presented. Studies to optimize the imaging of 188 Re “in vivo” have also continued, including the characterization of H8500 Flat Panel PMT and of LaBr 3 crystals, and the development of dedicated electronics.

188Re is a beta- (Emax = 2.12 MeV) and gamma (155 keV) emitter. Since its chemistry is similar to that of the largely employed tracer, 99mTc, molecules of hyaluronic acid (HA) have been labelled with 188Re to produce a target specific radiopharmaceutical. The radiolabeled compound, i.v. injected in healthy mice, is able to accumulate into the liver after a few minutes. To study the effect of metabolic radiotherapy in mice, we have built a small gamma camera based on a matrix of YAP:Ce crystals, with 0.6x0.6x10 mm**3 pixels, read out by a R2486 Hamamatsu PSPMT. A high-sensitivity 20 mm thick lead parallel-hole collimator, with hole diameter 1.5 mm and septa of 0.18 mm, is placed in front of the YAP matrix. Preliminary results obtained with various phantoms containing a solution of 188Re and with C57 black mice injected with the 188Re-HA solution are presented. To increase the space resolution and to obtain two orthogonal projections simultaneously we are building in parallel two new cameras to be positioned at 90 degrees. They use a CsI(Tl) matrix with 1x1x5 mm**3 pixels read out by H8500 Hamamatsu Flat panel PMT., Comment: 6 pages, 8 figs. To appear in Nucl. Phys. B (PS), proc. of Innovative Particle and Radiation Detectors, Siena, 23-26 May 2004

Physical properties of a position-sensitive camera for the analysis of biodistributions of gamma- and beta-emitting radiopharmaceuticals in small animals have been studied, in order to achieve optimal operating conditions. The camera consisted of a highly segmented yttrium-aluminate perovskite (YAP) scintillator, coupled to a position-sensitive photomultiplier. The energy resolution, the detection efficiency, the spatial resolution, the spatial linearity and the count-rate linearity of the YAP camera have been determined. Images related to initial activity levels and successive biodistribution evolution in mice organs are presented as an illustration of the camera performance.

The PN 2 S N-(N-(3-diphenylphosphinopropionyl)glycyl)cysteine ligand was conjugated to methoxy-poly(ethylene glycol)-amino (mPEG-NH 2 ) 5 and 20 kDa to yield PN 2 S(Trt)-PEG 5 0 0 0 1 and PN 2 S(Trt)-PEG 2 0 0 0 0 2, and thendetritylated to PN 2 S-PEG 5 0 0 0 4 and PN 2 S-PEG 2 0 0 0 0 5. When an acidic solution of 9 9 m TcO 4 - is added to 4 or 5 in solid form, a quantitative yield in a single labeled species, 9 9 m Tc-labeled PN 2 S-PEG 5 0 0 0 9 and 9 9 m Tc-labeled PN 2 S-PEG 2 0 0 0 0 10, respectively, is obtained. The reaction occurs in less than 15 min at room temperature for 4 and 35 °C for 5. This labeling procedure avoids the use of an external reducing agent, and it is based on the amphiphilic properties of PN 2 S-PEGs. Once in water, 4 and 5 self-assemble in micelles, which catalyze the metal reduction by means of an electron pair transfer from the phosphorus to technetium. The [ 9 9 m TcO] 3 + species is then coordinated, and at micelle level, both the (P)ON 2 S and the PN 2 S coordinations are possible, as demonstrated by reacting 9 9 m Tc-gluconate and ReOCl 3 (PPh 3 ) 2 with 4 and 5 and with the oxidized analogous (P)ON 2 S-PEG 5 0 0 0 6. Compounds 9 and 10 exhibited a high stability both in vitro and in vivo. Biodistribution studies in mice also indicated that PN 2 S linking and 9 9 m Tc labeling do not modify PEG behavior in water and in vivo since the polymer dictates the fate of the conjugate.

Purpose: The purpose is to evaluate the CD44-mediated cellular targeting of HA-But, a hyaluronic acid esterified with butyric acid (But) residues, to hepatocellular carcinoma cell lines in vitro and to hepatic tumor metastases in vivo. Experimental Design: In vitro, the CD44-dependent cytotoxicity in two human hepatocellular carcinoma cell lines (HepB3 and HepG2) with high and low CD44 expression was investigated; in vivo, the effect on liver metastases originating from intrasplenic implants of Lewis lung carcinoma (LL3) or B16-F10 melanoma in mice was compared with the pharmacokinetics of organ and tissue distribution using different routes of administration. Results: HepB3 and HepG2 cell lines showed different expression of CD44 (78 and 18%, respectively), which resulted in a CD44-dependent HA-But inhibitory effect as demonstrated also by the uptake analysis performed using radiolabeled HA-But (99mTc-HA-But). Pharmacokinetic studies showed different rates of 99mTc-HA-But distribution according to the route of administration (i.v., i.p., or s.c.): very fast (a few minutes) after i.v. treatment, with substantial accumulation in the liver and spleen; relatively slow after i.p. or s.c. treatment, with marked persistence of the drug at the site of injection. The effect of s.c. and i.p. treatment with HA-But on liver metastases originating from intrasplenic implants of LL3 carcinoma or B16-F10 melanoma (both CD44-positive: 68 and 87%, respectively), resulted in 87 and 100% metastases-free animals, respectively (regardless of the route of administration), and a significant prolongation of the life expectancy compared with control groups. Conclusions: HA-But tends to concentrate in the liver and spleen and appears to be a promising new drug for the treatment of intrahepatic tumor lesions.

Cholecystokinin (CCK) receptors of the subtype B (CCK-BR) have been shown to be overexpressed in certain neuroendocrine tumors including medullary thyroid cancer. Our recent work has focused on new methods to radiolabel the CCK8 peptide with In-111 or Tc-99m for CCK-B receptor imaging. Derivatives of CCK8 were obtained by addition at the N-terminus in solid phase of a DTPA derivative (DTPAGlu) linked through a glycine spacer (DTPAGlu-G-CCK8) or cysteine, glycine and a diphenylphosphinopropionyl moiety (PhosGC-CCK8) for labeling with In-111 and 99mTc, respectively. CCK-BR overexpressing A431 cancer cell lines were utilized to characterize in vitro Properties of the two compounds as well as for generating xenografts in nude mice for in vivo characterization. Both In-111-DTPAGlu-G-CCK8 and (99m)TcPhosGC-CCK8 showed similar binding affinities for CCK-BR with dissociation constants of 20-40 nM, were internalized after interaction with the receptor and displayed prolonged cellular retention times. Specific in vivo interaction with the receptor of both CCK8 analogs was observed in our animal model In-111-DTPAGlu-G-CCK8 showed better target to non-target ratios, although it appeared to be rapidly metabolized after injection and activity cleared through the kidneys. Tc-99m-PhosGC-CCK8 was more stable in vivo but showed marked hepatobiliary clearance with resulting high background activity in the bowel. The rapid clearance and lower background obtained with 111In-DTPAGlu-G-CCK8 make this a better candidate for further development.

The PN(2)S chelate N-[N-(3-diphenylphosphinopropionyl)glycyl]-S-tritylcysteine methyl ester [PN(2)S(Trt)-OMe] was synthesized and reacted with ReOCl(3)(PPh(3))(2) and Ph(4)P[ReOCl(4)]. The reactions of both tritylated and detritylated ligands with Re(V)O precursors gave two diastereomers, 9a and 9b, of the ReO(PN(2)S-OMe) complex. The two isomers, produced in a 1:1 molar ratio, are stable and do not interconvert. They were separated by reverse-phase HPLC and characterized by NMR, FT-IR, and UV-visible spectroscopy and electrospray mass spectrometry. X-ray analysis established for 9a the presence in the solid of the syn isomer. Compound 9a, C(21)H(23)N(2)O(5)PSRe, crystallized from warm acetonitrile in the triclinic space group Ponemacr;, a = 9.828(2) A, b = 11.163(2) A, c = 11.641(2) A, alpha = 106.48(3) degrees, beta = 109.06(3) degrees, gamma = 102.81(3) degrees, V = 1085.7(4) A(3), Z = 2. The PN(2)S coordination set is in the equatorial plane, and the complex shows a distorted square pyramidal coordination. The anti configuration assigned to 9b is consistent with all the available physicochemical data. Follow-up of the reaction of the detritylated ligand with Ph(4)P[ReOCl(4)] in ethanol or acetonitrile indicated that the phosphorus atom of the chelate binds first to the metal and that this bond acts as the driving force for coordination.

The aim of this study was to investigate whether technetium-99m labelled fluconazole can distinguish fungal from bacterial infections. Fluconazole was labelled with (99m)Tc and radiochemical analysis showed less than 5% impurities. The labelling solution was injected into animals with experimental infections. For comparison, we used two peptides for infection detection, i.e. UBI 29-41 and hLF 1-11, and human IgG, all labelled with (99m)Tc. Mice were infected with Candida albicans or injected with heat-killed C. albicans or lipopolysaccharides to induce sterile inflammation. Also, mice were infected with Staphylococcus aureus or Klebsiella pneumoniae. Next, accumulation of (99m)Tc-fluconazole and (99m)Tc-labelled peptides/IgG at affected sites was determined scintigraphically. (99m)Tc-fluconazole detected C. albicans infections (T/NT ratio=3.6+/-0.47) without visualising bacterial infections (T/NT ratio=1.3+/-0.04) or sterile inflammatory processes (heat-killed C. albicans: T/NT ratio=1.3+/-0.2; lipopolysaccharide: T/NT ratio=1.4+/-0.1). C. albicans infections were already seen within the first hour after injection of (99m)Tc-fluconazole (T/NT ratio=3.1+/-0.2). A good correlation (R(2)=0.864; P0.05) between T/NT ratios for this tracer and the number of viable C. albicans was found. Although (99m)Tc-UBI 29-41 and (99m)Tc-hLF 1-11 were able to distinguish C. albicans infections from sterile inflammatory processes in mice, these (99m)Tc-labelled peptides did not distinguish these fungal infections from bacterial infections. It is concluded that (99m)Tc-fluconazole distinguishes infections with C. albicans from bacterial infections and sterile inflammations.

A novel CCK8 derivative bearing a chelating agent at its N- end and its oxo-rhenium(V) complex have been synthesized and characterized. The chelating agent N-[N-13-(diphenylphosphino)propionyl]glycyl]cysteine (PN2S) ligand, the coordination set of which is made by the phosphorus atom of phosphine, the nitrogen atoms of the two amido groups and the sulphur atom of cysteine, has been used due to its high affinity towards the oxo-rhenium(V) moiety. Molecular modelling studies indicate that the CCK8 peptide adopts the right conformation for cholecystokinin receptor binding, and that modifications on the N-terminal side of CCK8 obtained by introducing chelating agents and its metal complexes should not affect the interaction with CCK(A) receptor.

This article reviews possible use of 18 F-labelled radiopharmaceuticals in oncology with positron emission tomography. The characteristics of various 18 F-labelled compounds are proteins and peptides, those that bind to · receptors, agents to assess hypoxia, and agents to evaluate gene therapy are highlighted. Furthermore, different 18 F-labelled tissue specific agents are indicated for the detection and monitoring of various malignancies: melanoma, brain tumours, breast cancer, prostate cancer and colorectal cancer. 18 F-fluorodeoxyglucose has been excluded from this summary.

A phosphine-containing ligand providing a N-{N-[3-(diphenylphosphino)propionyl]glycyl}-L-S-benzyl-cystein (PNNS) donor atomset for the chelation of 99m Tc was studied in labelling experiments with a model peptide (tetragastrin, cholecystokinin-fragment). The peptide was conjugated to the ligand chelator by active ester chemistry either before or after radiolabelling. Both the chelator-conjugate and the preformed chelate approaches resulted in the same radiolabelled isomers of the ligand peptide. Sequence and reaction conditions influence yield and purity.

The co-ordination of dipeptides modified with a phosphine group to the ReO 3+ core has been studied, and the new donor sets PN 2 X (X = O or S) achieved. N-{N-[3-(Diphenylphosphino)propionyl]glycyl }-L-S-benzylcysteine (H 3 L 2 ) and its methyl ester derivative (H 2 L 1 ) have been used for preparing six-co-ordinated oxorhenium(V) complexes, providing a new chelating system for targeting 186/188 Re to protein bioactive molecules. The complexes have been characterized by means of UV/VIS, IR, FAB and 1 H NMR spectroscopy. The crystal structures of [ReO(L 2 )(OH 2 )]·H 2 O·MeOH and [ReO(L 1 )Cl] have been established. In both the complexes the co-ordination geometry is distorted octahedral. The ligands are tetradentate, co-ordinating the ReO 3+ moiety through the phosphine phosphorus, the two deprotonated amide nitrogens and the O or S atom from the carboxylate or thioether groups. When the cysteine carboxylic moiety is free, it can replace, in organic solvents, the thioether sulfur to give a stable complex, the fourth donor atom in the equatorial plane being a carboxylate oxygen. In basic medium [ReO(L 1 )Cl] underwent substitution of Cl - by OH - , evidence for the high stability of the PN 2 S donor set.

The reactions of [ReOCl4]- with Schiff base ligands derived from salicylaldehyde and 1,5-diaminopentane (H2L1a), -hexane (H2L1b), -heptane (H2L1c) or diethylentriamine (H3L2) have been investigated. The complexes ReOCl2(EtOH)HL1n (I) (n = a, b or c), Re2O2(MeOH)2Cl4HL2 (II), ReOClL1n (III) and ReOL2 (IV), have been synthesized and characterized with the usual physicochemical measurements. The crystal structure of ReOL2 was determined by single crystal X-ray methods. Crystals are monoclinic, space group P2(1)/c, with a = 9.470(7), b = 9.358(8), c = 21.859(12) angstrom, beta = 99.23(8)-degrees and Z = 4. X-ray diffraction provides 5601 observed reflections (up to 2-theta = 60-degrees) and the structure has been refined by full-matrix least-squares methods to R = 0.061. The monomeric structure consists of distorted octahedral ReOL2 units. One oxygen atom of the N3O2 pentadentate ligand is located trans to the rhenium-oxo-oxygen bond, while the remaining four coordinating atoms lie on the equatorial plane of the octahedron assuming that the oxo-oxygen occupies an apex. The arrangement of the two iminophenolate groups is explained as a function of the length of the aliphatic chain joining the two imine groups.

The reactions of (o-aminophenyl)diphenylphosphine (HL) with ammonium pertechnetate have been investigated. The complexes [TcL3] 1 and [TcL2(HL)]+ 2, with [TcO4]-, [ClO4]- and [CF3CO2]- as counter anions, were isolated from the reaction mixture depending on the pH. The transformation of 1 into 2, and vice versa, was identified as an acid-base equilibrium by UV/VIS spectrophotometric measurements. The products have been characterized by means of the usual physicochemical determinations. Compound 2, as its perchlorate salt, has been studied by means of X-ray analysis. It exhibits a distorted-octahedral configuration in a monoclinic crystal system: space group P2(1)/n, a = 11.009(2), b = 19.361 (3), c = 24.473(3) angstrom, beta = 100.76(1)-degrees and Z = 4. The structure was solved by Patterson and Fourier methods and refined by least-squares methods to R = 0.052 using 5096 observed reflections. Relevant bond lengths and angles are: Tc-P(1) 2.483(2), Tc-P(2) 2.430(2), Tc-P(3) 2.436(2), Tc-N(1) 2.048(5), Tc-N(2) 1.948(5), Tc-N(3) 1.979(5) angstrom; P(2)-Tc-P(3) 160.2(1), P(1)-Tc-N(3) 164.3(2), N(1)-Tc-N(2) 163.6(2)-degrees.

Six-co-ordinate complexes of technetium(V) and rhenium(V) containing the MO3+ (M = Tc or Re) core were synthesized from [MOCl4]- via ligand-exchange reactions using tridentate Schiff-base ligands containing the ONN donor-atom set. The complexes of general formula [MOCl2Ln] [n = 1-4; L1 = 1-(8?-quinolyliminomethyl)-2-naphtholate, L2 = N-(8?-quinolyl)salicylideneiminate, L3 = 3-methoxy-N-(8?-quinolyl)salicylideneiminate, L4 = N-(2?-dimethylaminoethyl)salicylideneiminate] were characterized by means of physico-chemical measurements and [TcOCl2L1] also by X-ray diffraction analysis. The technetium co-ordination environment in the last complex is a distorted octahedron with the N2O ligand-atom set and the oxo-oxygen occupying the equatorial plane and the two chlorine atoms, respectively trans, in axial positions. The complex crystallizes in monoclinic space group P21/a with a = 23.262(8), b = 7.301(4), c = 11.444(5)Å, ? = 98.98(5)°, and Z = 4. The structure has been refined to R = 0.048 for 2 693 observed reflections.

The ligand o-(dipheny1phosphino)benzaldehyde (Ph2P-C6H4CHO) is one of the simplest possible bidentate 0,P-chelating phosphine ligands. We have studied the reaction of this ligand with oxotetrachlorotechnetate(V) and observed an unexpected Tc(IV) product containing an 2P2-tetradentate ligand. The synthesis and X-ray structural characterization of this unusual product are now reported. .....

A new series of five-co-ordinate rhenium(III) complexes containing the mixed S,P-bidentate 2-(diphenylphosphino)ethanethiolate ligand together with a monothiol RSH [R = Ph2PCH2CH2, Ph2P(O)CH2CH2, PhCH2, Ph or Prn] have been synthesized and characterized. This ReIIIP2S3 series was prepared by substitution reactions of [ReIIICl3(MeCN)(PPh3)2], a pre-reduced rhenium(III) precursor, by addition of 2-(diphenylphosphino)ethanethiol and the corresponding monothiol. Formation of these compounds was verified by elemental analysis and 1H and 31P NMR and positive-ion fast atom bombardment mass spectroscopy. The complexes were found to be diamagnetic, neutral and stable. They exhibit a trigonal-bipyramidal geometry, where three sulfur atoms occupy the equatorial plane and two phosphorus atoms are positioned at the apices. The X-ray structural analysis of bis[2-(diphenylphoshino)ethanethiolato-κS,κP](phenylmethanethiolato-κS)rhenium(III) revealed that this compound crystallizes in the monoclinic space group P21/c with Z= 8, a= 21.011(9), b= 20.397(9), c= 16.289(7)A, β= 107.13(5)°, R= 0.050, R′= 0.063, by using 5644 observed reflections. The above data further demonstrate the preference of a five-co-ordinate configuration when the P2S3 donor-atom set is available for co-ordinating rhenium(III).

The reactions of the [TcO4]– anion with PPh3 in various concentrations of HCl are reported. [TcCl4(PPh3)2], [TcCl5(PPh3)]–, and [TcCl6]2– were obtained and the anionic complexes were isolated with cations such as [PPh3H]+, [AsPh4]+, or [Ph3PC(Me)2CH2COMe]+. The crystal structure of the title complex was determined at –100 °C from 1 761 independent reflections and refined to R= 0.065. Crystals are monoclinic, space group P21/n, a= 21.909(4), b= 18.963(4), c= 9.896(3)A, β= 103.05(5)°, and Z= 4. The structure consists of well separated units of octahedral [TcCl5(PPh3)]– anions, and tetrahedral phosphonium cations, in which the phenyl groups are in a ′ propeller ′ configuration around P. Selected bond distances and angles are Tc–Cl (mean) 2.34(1), Tc–P 2.57(1)A, Cl–Tc–Cl (mean) 90.7(4), Cl–Tc–P 88.7(4)°.

The electrode reduction of the technetium 99 phosphine complexes TcCl 3 (PMe 2 Ph) 3 and TcCl 4 (PMe 2 Ph) 2 has been studied in acetonitrile solvent by electroanalytical techniques. The electrode processes, as well as the involved chemical equilibria, have been studied. Technetium(II) and technetium(I) phosphine complexes have been obtained by reducing TcCl 3 (PMe 2 Ph) 3 at different potential values. The voltammetric behaviour of these compounds of technetium in low oxidation states has been also reported. TcCl 4 (PMe 2 Ph) 2 undergoes an one-electron reduction giving rise to TcCl 3 (PMe 2 Ph) 3 as the main product.

Six-coordinated tris(monothio-β-diketonates) of Tc(III) and Re(III) have been synthesized by the reaction of M(III) thiourea complexes with the appropriate monothio-β-diketone ligands in methanol. Characterization of the compounds by IR, UV-Vis, 1H NMR and mass spectroscopy indicates that the ligands coordinate as bidentate. The 1H NMR spectra of the paramagnetic substances are well resolved and the chelate ring protons show a large high-field shift of the Tc complcxes and a low-field shift of the corresponding Re analogues. A complete crystal and molecular structure determination, performed on tris(monothiodibenzoylmethanato)technetium(III), is the first structural characterization of a Tc(III) compound with O and S chelate ligands.