Fresh Impetus in the Chemistry of Calcium Peroxides.

Redox-inactive metal ions are essential in modulating the reactivity of various oxygen-containing metal complexes and metalloenzymes, including photosystem II (PSII). The heart of this unique membrane-protein complex comprises the Mn4CaO5 cluster, in which the Ca2+ ion acts as a critical cofactor in the splitting of water in PSII. However, there is still a lack of studies involving Ca-based reactive oxygen species (ROS) systems, and the exact nature of the interaction between the Ca2+ center and ROS in PSII still generates intense debate. Here, harnessing a novel Ca-TEMPO complex supported by the ß-diketiminate ligand to control the activation of O2, we report the isolation and structural characterization of hitherto elusive Ca peroxides, a homometallic Ca hydroperoxide and a heterometallic Ca/K peroxide. Our studies indicate that the presence of K+ cations is a key factor controlling the outcome of the oxygenation reaction of the model Ca-TEMPO complex. Combining experimental observations with computational investigations, we also propose a mechanistic rationalization for the reaction outcomes. The designed approach demonstrates metal-TEMPO complexes as a versatile platform for O2 activation and advances the understanding of Ca/ROS systems.

Long-Acting Injectable Antipsychotics-A Review on Formulation and In Vitro Dissolution.

Long-acting injectable (LAI) neuroleptics constitute an effective therapeutical alternative for individuals suffering from persistent mental illness. These injectable pharmaceuticals help patients manage their condition better and improve long-term outcomes by preventing relapses and improving compliance. This review aims to analyse the current formulation aspects of LAI neuroleptics, with particular emphasis on analysis of drug release profiles as a critical test to guarantee drug quality and relevant therapeutical activity. While there is no officially approved procedure for depot parenteral drug formulations, various dissolution tests which were developed by LAI manufacturers are described. In vitro dissolution tests also possess a critical function in the estimation of the in vivo performance of a drug formulation. For that reason, thorough inspection of the in vitro-in vivo correlation (IVIVC) is also discussed.

Facile and cost-effective technique to control europium oxidation states in glassy fluorophosphate matrices with tunable photoluminescence.

Inorganic fluorophosphate glasses doped with Eu[Formula: see text]/Eu[Formula: see text] are potential candidates for phosphors for commercial white LEDs. This report presents a fast, inexpensive and effective method of controlling the relative concentrations of Eu[Formula: see text]/Eu[Formula: see text] photoluminescent centers in these glasses. The technique consists of a fast quenching of the melt of initial reagents under appropriate conditions. Eu[Formula: see text]/Eu[Formula: see text] ratio was controlled by carrying out the melting under a reducing atmosphere at a temperature between 1000 and 1200 [Formula: see text]C for periods of 5 to 15 minutes. The reducing atmosphere was provided by a 'double crucible' technique and did not require special gas lines during the synthesis. The samples were studied by several complementary experimental methods (X-ray diffractometry-XRD, X-ray photoelectron spectroscopy-XPS, photoluminescence-PL-and photoluminescence excitation-PLE-spectroscopies as well as optical transmission spectroscopy). It was shown that the syntheses resulted in amorphous materials with different relative Eu[Formula: see text]/Eu[Formula: see text] concentration ratios, strongly dependent on the preparation conditions: the temperature and the time of melting in a reducing atmosphere. Moreover, changes in these ratios strongly affected the materials' PL and PLE spectra. Demonstration of reproducible smooth transition from amaranth to blue luminescence color, with white in between, was the most spectacular result of this work.

Novel High-Pressure Nanocomposites for Cathode Materials in Sodium Batteries.

A new nanocomposite material was prepared by high pressure processing of starting glass of nominal composition NaFePO4. Thermal, structural, electrical and dielectric properties of the prepared samples were studied by differential thermal analysis (DTA), X-ray diffraction (XRD) and broadband dielectric spectroscopy (BDS). It was demonstrated that high-pressure-high-temperature treatment (HPHT) led to an increase in the electrical conductivity of the initial glasses by two orders of magnitude. It was also shown that the observed effect was stronger than for the lithium analogue of this material studied by us earlier. The observed enhancement of conductivity was explained by Mott's theory of electron hopping, which is more frequent in samples after pressure treatment. The final composite consisted of nanocrystalline NASICON (sodium (Na) Super Ionic CONductor) and alluaudite phases, which are electrochemically active in potential cathode materials for Na batteries. Average dimensions of crystallites estimated from XRD studies were between 40 and 90 nm, depending on the phase. Some new aspects of local dielectric relaxations in studied materials were also discussed. It was shown that a combination of high pressures and BDS method is a powerful method to study relaxation processes and molecular movements in solids. It was also pointed out that high-pressure cathode materials may exhibit higher volumetric capacities compared with commercially used cathodes with carbon additions.

Highly Conducting Li(Fe1-xMnx)0.88V0.08PO4 Cathode Materials Nanocrystallized from the Glassy State (x = 0.25, 0.5, 0.75).

This study showed that thermal nanocrystallization of glassy analogs of LiFe1-xMnxPO4 (with the addition of vanadium for improvement of glass forming properties) resulted in highly conducting materials that may be used as cathodes for Li-ion batteries. The glasses and nanomaterials were studied with differential thermal analysis, X-ray diffractometry, and impedance spectroscopy. The electrical conductivity of the nanocrystalline samples varied, depending on the composition. For x=0.5, it exceeded 10-3 S/cm at room temperature with an activation energy as low as 0.15 eV. The giant and irreversible increase in the conductivity was explained on the basis of Mott's theory of electron hopping and a core-shell concept. Electrochemical performance of the active material with x=0.5 was also reported.

Facile and reproducible method of stabilizing [Formula: see text] phases confined in nanocrystallites embedded in amorphous matrix.

Bismuth sesquioxide ([Formula: see text]) draws much attention due to wide variety of phases in which it exists depending on the temperature. Among them, [Formula: see text] phase is specially interesting because of its high oxide ion conductivity and prospects of applications as an electrolyte in fuel cells. Unfortunately, it is stable only in a narrow temperature range ca. 730-830 [Formula: see text]C. Our group has developed a facile and reproducible two-stage method of stabilizing [Formula: see text] crystalline phases confined in nanocrystallites embedded in amorphous matrix. In the first stage, glassy materials were obtained by a routine melt-quenching method: pure [Formula: see text] powders were melted in porcelain crucibles and fast-cooled down to room temperature. In the second step, the materials were appropriately heat-treated to induce formation of crystallites of [Formula: see text], [Formula: see text] or [Formula: see text] [Formula: see text] phases confined in a glassy matrix, depending on the process conditions. It was found out that the vitrification of the initial [Formula: see text] and the subsequent nanocrystallization were unexpectedly possible due to the presence of some Al, and Si impurities from the crucibles. Systematic DTA, XRD, optical, Raman and SEM/EDS studies were carried out to investigate the influence of the syntheses processes and allowed us to determine conditions under which the particular phases appear and remain stable down to room temperature.

Towards the High Phase Purity of Nanostructured Alluaudite-Type Glass-Ceramics Cathode Materials for Sodium Ion Batteries.

Alluaudite-type materials are systematically attracting more attention as prospective cathode materials for sodium ion batteries. In this paper, we strove to optimize various synthesis parameters of three alluaudite compositions (Na2Fe3(PO4)3-FFF, Na2VFe2(PO4)3-VFF, and Na2VFeMn(PO4)3-VFM) to obtain nanostructured alluaudite-type glass-ceramics with high phase purity. We systematically investigated the role of the chemical reactions, temperature and time of melting, cooling rate, and reducing factors on the quality of the final products. A detailed synthesis protocol along with X-ray diffractometry, thermal analysis, scanning electron microscopy imaging, and electrical conductivity measurements (with impedance spectroscopy) are reported. As a result, a significant increase of the conductivity was observed in the nanomaterials. The highest value was reached for the VFF composition and was equal to 6×10-4 S/cm at room temperature.

Effectiveness of the Oxygenation over Classical Protonolysis Reactions: A Case of Alkylzinc Complexes Incorporating an Aminoalcoholate Ligand.

Alkylzinc aminoalcoholates have emerged as powerful catalysts in organic synthesis and polymerization processes. Despite extensive research, difficulties in the rational design of these catalytic systems and in-depth understanding of their modes of action have hitherto been encountered. Most of the major obstacles stem largely from the relatively limited knowledge of the structure-activity relationship of zinc catalysts. In fact, the key active species are often generated in situ via the protonolysis of the alkylzinc precursors, which precludes their isolation and detailed characterization. Herein, the effectiveness of the oxygenation over the classical protonolysis in the synthesis of zinc alkylperoxides stabilized by an aminoalcoholate ligand is demonstrated. The controlled oxygenation of a tert-butylzinc complex incorporating a pridinolum (prinol) ligand leads to well-defined a dinuclear adduct of a (prinol)ZnOOtBu moiety with the parent tBuZn(prinol) complex and a novel dimer [tBuOOZn(prinol)]2 with terminal alkylperoxide groups. The observed reaction outcomes strongly depend on the reaction conditions. Although sparse examples of heteroleptic adducts of the [RZn(L)]x [ROOZn(L)]y -type are known, the herein reported homoleptic [ROOZn(L)]x aggregate is unprecedented. Strikingly, comparative studies involving reactions between tBuZn(prinol) and tert-butylhydroperoxide or ethanol revealed that the respective seemingly simple zinc alkylperoxides, or zinc alkoxides, respectively, are not accessible via the classical alcoholysis. We believe that these game-changing results concerning multifaceted chemistry of organozinc aminoalcoholates should pave the way for more rational development of various Zn-based catalytic systems.

Towards Higher Electric Conductivity and Wider Phase Stability Range via Nanostructured Glass-Ceramics Processing.

This review article presents recent studies on nanostructured glass-ceramic materials with substantially improved electrical (ionic or electronic) conductivity or with an extended temperature stability range of highly conducting high-temperature crystalline phases. Such materials were synthesized by the thermal nanocrystallization of selected electrically conducting oxide glasses. Various nanostructured systems have been described, including glass-ceramics based on ion conductive glasses (silver iodate and bismuth oxide ones) and electronic conductive glasses (vanadate-phosphate and olivine-like ones). Most systems under consideration have been studied with the practical aim of using them as electrode or solid electrolyte materials for rechargeable Li-ion, Na-ion, all-solid batteries, or solid oxide fuel cells. It has been shown that the conductivity enhancement of glass-ceramics is closely correlated with their dual microstructure, consisting of nanocrystallites (5-100 nm) confined in the glassy matrix. The disordered interfacial regions in those materials form "easy conduction" paths. It has also been shown that the glassy matrices may be a suitable environment for phases, which in bulk form are stable at high temperatures, and may exist when confined in nanograins embedded in the glassy matrix even at room temperature. Many complementary experimental techniques probing the electrical conductivity, long- and short-range structure, microstructure at the nanometer scale, or thermal transitions have been used to characterize the glass-ceramic systems under consideration. Their results have helped to explain the correlations between the microstructure and the properties of these systems.

Towards deeper understanding of multifaceted chemistry of magnesium alkylperoxides.

Despite considerable progress in the multifaceted chemistry of non-redox-metal alkylperoxides, the knowledge about magnesium alkylperoxides is in its infancy and only started to gain momentum. Harnessing the well-defined dimeric magnesium tert-butylperoxide [(f5BDI)Mg(µ-η2:η1-OOtBu)]2 incorporating a fluorinated ß-diketiminate ligand, herein, we demonstrate its transformation at ambient temperature to a spiro-type, tetranuclear magnesium alkylperoxide [(f5BDI)2Mg4(µ-OOtBu)6]. The latter compound was characterized by single-crystal X-ray diffraction and its molecular structure can formally be considered as a homoleptic magnesium tert-butylperoxide [Mg(µ-OOtBu)2]2 terminated by two monomeric magnesium tert-butylperoxides. The formation of the tetranuclear magnesium alkylperoxide not only contradicts the notion of the high instability of magnesium alkylperoxides, but also highlights that there is much to be clarified with respect to the solution behaviour of these species. Finally, we probed the reactivity of the dimeric alkylperoxide in model oxygen transfer reactions like the commonly invoked metathesis reaction with the parent alkylmagnesium and the catalytic epoxidation of trans-chalcone with tert-butylhydroperoxide as an oxidant. The results showed that the investigated system is among the most active known catalysts for the epoxidation of enones.

Unveiling Complexity of the Oxygenation of Aluminum Alkyls by the Isolation of Unique Alkylperoxide and Oxoalkoxide Compounds.

While aluminum alkyls are often considered to be exemplary compounds of main-group organometallics and an in-depth understanding of their multifaceted chemistry is continually vital, the controlled oxygenation of organoaluminum complexes still remains a largely undeveloped area. In the course of our systematic studies on the relationship between the Lewis acidity of metal centers and noncovalent interactions in the secondary coordination sphere, we report the oxygenation of dialkylaluminum complexes incorporating a pyrrole-ester ligand, as purposefully selected dormant Lewis acidic octet-compliant model compounds, and the isolation and characterization of a new, dimeric aluminum tert-butylperoxide and an unique example of an aluminum oxoethoxide cluster. Our studies provide a more in-depth look at the diversity and complexity of the oxygenation chemistry of aluminum alkyls.

Multifold pressure-induced increase of electric conductivity in LiFe0.75V0.10PO4 glass.

We investigated the impact of high pressure and high-temperature annealing on lithium-vanadium-iron-phosphate (LiFe0.75V0.10PO4) glass materials, proposed for the use in cathodes for high-performance batteries. The treatment was carried out below the glass transition temperature (Tg ≈ 483 °C) at P = 1 GPa pressure, in an argon atmosphere. It led to the multifold electrical conductivity increase. Broadband dielectric spectroscopy (BDS) measurements before and after the process revealed the strong DC-conductivity increase across the whole studied frequency range by two orders of magnitude. The phenomenon is explained using Mott's theory of polaron hopping in disordered solids containing transition metal oxides. The pressure evolution of the glass transition temperature and the crystallisation temperature above Tg is shown.

An In-Depth Look at the Reactivity of Non-Redox-Metal Alkylperoxides.

Over the past 150 years, a certain mythology has arisen around the mechanistic pathways of the oxygenation of organometallics with non-redox-active metal centers as well as the character of products formed. Notably, there is a widespread perception that the formation of commonly encountered metal alkoxide species results from the auto-oxidation reaction, in which a parent metal alkyl compound is oxidized by the metal alkylperoxide via oxygen transfer reaction. Now, harnessing a well-defined zinc ethylperoxide incorporating a ß-diketiminate ligand, the investigated alkylperoxide compounds do not react with the parent metal alkyl complex as well as Et2 Zn to form a zinc alkoxide. Upon treatment of the zinc ethylperoxide with Et2 Zn, a previously unobserved ligand exchange process is favored. Isolation of a zinc hydroxide carboxylate as a product of decomposition of the parent zinc ethylperoxide demonstrates the susceptibility of the latter to O-O bond homolysis.

Reaching Milestones in the Oxygenation Chemistry of Magnesium Alkyls: towards Intimate States of O2 Activation and the First Monomeric Well-Defined Magnesium Alkylperoxide.

Despite decades of extensive studies on the reactivity of magnesium alkyls towards O2 , the isolation and structural characterization of discrete products of these reactions still remains a challenge. Although the formation of the most frequently encountered magnesium alkoxides through unstable alkylperoxide intermediates has commonly been accepted, the latter species have been elusive for over 100 years. Probing the oxygenation of a seemingly simple well-defined neo-pentylmagnesium complex stabilized by a ß-diketiminate ligand, (dipp BDI)MgCH2 CMe3 , we report on the isolation and structure characterization of both a dimeric magnesium alkoxide [(dipp BDI)Mg(µ-OCH2 CMe3 )]2 and the first example of monomeric magnesium alkylperoxide [(dipp BDI)Mg(thf)OOCH2 CMe3 ] (dipp BDI=[(ArNCMe)2 CH]- and Ar=C6 H3 iPr2 -2,6). The formation of monomeric magnesium alkylperoxide demonstrates a crucial role of an additional Lewis base for stabilizing the most elusive oxygenation products likely due to increasing of the electron density on the metal centre. Moreover, the 1 H NMR studies at -80 °C revealed that the dissociation of a coordinated Lewis base from the solvated complex (dipp BDI)Mg(L)CH2 CMe3 (where L=thf or 4-methylpyridine) is likely not required prior to the effective attack of an O2 molecule on the metal centre and the four-coordinate alkylmagnesium complex reacts smoothly with O2 under these conditions. The results can be expected to aid future engineering of various organomagnesium/O2 -based reaction systems.

Oxygenation of RZn(N,O)-type complexes as an efficient route to zinc alkoxides not accessible via the classical alcoholysis path.

The controlled oxygenation of alkylzinc complexes supported by a 2-ester substituted pyrrolate ligand (L) leads to zinc alkoxides with an uncommon structural motif in the solid state: a trimer [(L)Zn(µ-OtBu)]3 with the central [Zn3(µ-OR)3] ring and a tetramer [(L)Zn(µ3-OEt)]4 with a heterocubane-type structure. Strikingly, these seemingly simple zinc alkoxides are not accessible via the classical alcoholysis route.

Unprecedented Variety of Outcomes in the Oxygenation of Dinuclear Alkylzinc Derivatives of an N,N-Coupled Bis(ß-diketimine).

Reactions between O2 and organometallics with non-redox-active metal centers have received continuous interest for over 150 years, although significant uncertainties concerning the character and details of the actual mechanism of these reactions persist. Harnessing dinuclear three-coordinate alkylzinc derivatives of an N,N-coupled bis(ß-diketimine) proligand (LH2 ) as a model system, we demonstrate for the first time that a slight modification of the reaction conditions might have a dramatic influence on the oxygenation reaction outcomes, leading to an unprecedented variety of products originating from a single reaction system, that is, partially and fully oxygenated zinc alkoxides, zinc alkylperoxides, and zinc hydroxide compounds. Our studies indicate that accessibility of the three-coordinate zinc center by the O2 molecule, coupled with the lower reactivity of Zn-Me vs. Zn-Et units towards dioxygen, are key factors in the oxygenation process, providing a novel tetranuclear methyl(methoxy)zinc {[L][ZnMe][Zn(µ-OMe]}2 and zinc ethoxide {[L][Zn(µ-OEt)]2 }2 . Remarkably, oxygenation of three-coordinate alkylzinc [L][ZnR]2 complexes at ambient temperature afforded a unique hydroxide {[L][Zn(µ-OH)]2 }2 . Oxygenation of the [L][ZnEt]2 complex in the presence of 4-methylpyridine (py-Me) at low temperature led to the isolation of a dinuclear zinc ethylperoxide [L][Zn(OOEt)(py-Me)]2 , which nicely substantiates the intermediacy of an unstable zinc alkylperoxide in the formation of the subsequent zinc alkoxide and hydroxide compounds. Finally, our investigations provide compelling evidence that a non-redox-active metal center plays a crucial role in the oxygenation process through assisting in single-electron transfer from an M-C bond to an O2 molecule. Although the oxygenation of zinc alkyls occurs by radical pathways, the reported results stand in clear contradiction to the widely accepted free-radical chain mechanism.

Oxygenation Chemistry of Magnesium Alkyls Incorporating ß-Diketiminate Ligands Revisited.

Despite the fact that extensive research has been carried out, the oxygenation of alkyl magnesium species still remains a highly unexplored research area and significant uncertainties concerning the mechanism of these reactions and the composition of the resulting products persist. This case study compares the viability of the controlled oxygenation of alkylmagnesium complexes supported by ß-diketiminates. The structural tracking of the reactivity of (N,N)MgR-type complexes towards O2 at low temperature showed that their oxygenation led exclusively to the formation of magnesium alkylperoxides (N,N)MgOOR. The results also highlight significant differences in the stability of the resulting alkylperoxides in solution and demonstrate that [(BDI)Mg(µ-η2 :η1 -OOBn)]2 (in which BDI=[(ArNCMe)2 CH]- and Ar=C6 H3 iPr2 -2,6) can be easily transformed to the corresponding magnesium alkoxide [(BDI)MgOBn]2 at ambient temperature, whilst [(F3 BDI)Mg(µ-OOtBu)]2 (in which F3 BDI=[(ArNCMe)2 CH]- and Ar=C6 H2 F3 -2,4,6) is stable under similar conditions. The observed selective oxygenation of (N,N)MgR-type complexes to the corresponding (N,N)MgOOR alkylperoxides strongly contradicts the widely accepted radical-chain mechanism for the oxygenation of the main-group-metal alkyls. Furthermore, either the observed transformation of the alkylperoxide [(BDI)MgOOBn]2 to the alkoxide [(BDI)MgOBn]2 as well as the formation of an intractable mixture of products in the control reaction between the alkylperoxide [(F3 BDI)MgOOtBu]2 and the parent alkylmagnesium [(F3 BDI)MgtBu] complex are not in line with the common wisdom that magnesium alkoxide complexes' formation results from the metathesis reaction between MgOOR and Mg-R species. In addition, a high catalytic activity of well-defined magnesium alkylperoxides, in combination with tert-butyl hydroperoxide (TBHP) as an oxygen source, in the epoxidation of trans-chalcone is presented.

The preoperative maximum standardized uptake value measured by 18F-FDG PET/CT as an independent prognostic factor of overall survival in endometrial cancer patients.

PURPOSE: The aim of this study was to determine if the preoperative maximum standardized uptake value (SUVmax) measured by 18F-FDG PET/CT in the primary tumor has prognostic value in the group of patients with endometrial cancer. PATIENTS, MATERIALS, AND METHODS: A total of one hundred one consecutive endometrial cancer patients, age range 40-82 years (mean 62 years) and FIGO I-IV stage, who underwent 18-FDG-PET/CT within two weeks prior radical surgery, were enrolled to the study. The maximum SUV was measured and compared with the clinicopathologic features of surgical specimens. The relationship between SUVmax and overall survival was analyzed. RESULTS: The mean preoperative SUVmax was 14.34; range (3.90-33.80) and was significantly lower for FIGO I than for higher stages (P = 0.0012), as well as for grade 1 than for grade 2 and 3 (P = 0.018), deep myometrial invasion (P = 0.0016) and for high risk group (P = 0.0004). The analysis of survival ROC curve revealed SUVmax cut-off value of 17.7 to predict high risk of recurrence. Endometrial cancer patients with SUVmax higher than 17.7 characterized by lower overall survival. CONCLUSION: The preoperative SUVmax measured by 18F-FDG PET/CT is considered as an important indicator reflecting tumor aggressiveness which may predict poor prognosis. High value of SUVmax would be useful for making noninvasive diagnoses and deciding the appropriate therapeutic strategy for patients with endometrial cancer.

Evaluation of FLT-PET/CT usefulness in diagnosis and qualification for surgical treatment of gastric cancer.

AIM OF THE STUDY: Evaluation of FLT/PET/ CT usefulness in diagnosis and qualification for surgical treatment of gastric cancer. MATERIAL AND METHODS: The FLT/PET/CT test was carried out in a group of 50 gastric cancer patients. Based on the test result, a decision followed about the therapeutic procedure to be applied. A comparison was made with regards to the consistency of the cancer growth advancement degree evaluation in the initial preoperative FLT/PET/CT test against the evaluation of postoperative degree of cancer advancement in histopathology. RESULTS: In the group of 50 diagnosed patients a surgical treatment was used for 37 patients. 21 resections were performed out of which 19 operations were radical In the group of 16 non-resective operations 2 post-laparotomic patients were selected for inductive treatment. In the group of 13 patients who did not undergo any surgery, 10 were directed to palliative care and 3 for inductive treatment. In the group of 50 patients, the applied FLT-PET/CT test confirmed presence of primary tumor in 49 patients. The presence of increased uptake of FLT in the local lymph nodes during the preoperative FLT-PET/CT test was confirmed in 22 cases. In 14 patients with FLT-PET/Ct N(+) with the M(-) feature resection surgery was performed. The increased uptake of FLT in localizing metastases (nodal and non-nodal) FLT-PET/CT (M+) was detected in 22 patients. The presence of nodal metastases in the postoperative histopathology examination (hpN+) was detected in 14 cases. In these cases preoperative FLT-PET/CT test proved the N(+) feature in 11 patients. The result FLT-PET/CT N(-) was truly negative in 2 patients, and false negative in 1 patient. In the group of 7 operated hpN(-) patients, in 3 patients a preoperative result FLT-PET/ CT N(+) (false positive result) was obtained. The consistency (positive) of nodal metastases identification in FLT-PET/CT as compared to post-surgical histopathology examination scored 11/15, which equals 73.3%. In the group of patients in whom resection surgery was performed, 4 false negative results were obtained [hp(N+), FLT-PET/CT (N-)] and 3 false positive results [hp(N-), FLT-PET/CT N(+)]. CONCLUSIONS: The initial test results indicate that FLT-PET/CT is an effective method in evaluating the primary tumor and the regional lymph nodes and is useful and beneficial in the diagnosis and further treatment evaluation of gastric cancer. FLT-PET/CT examination facilitates making proper therapeutic decisions - it allows the number of unnecessary laparotomies to be lowered.

Can we rely on PET in the follow-up of advanced seminoma patients?

The management of residuals after completion of chemotherapy in advanced seminoma is controversial. It has been proposed that fluorodeoxyglucose-positron emission tomography (FDG-PET) can be used as a follow-up. In this study we investigated FDG-PET as a follow-up tool in advanced seminoma patients treated previously with chemotherapy or radiotherapy. Thirty-seven patients assigned to an advanced seminoma group based on CT and/or FDG-PET/CT and then treated with chemotherapy were included in the study. All these patients underwent FDG-PET/CT examination as a part of the follow-up scheme. Patients underwent retroperitoneal lymph node dissection (RPLND), radiotherapy, or were followed clinically by CT and/or PET/CT every 6 months. In 8 cases FDG-PET was positive: 5 of them underwent RPLND and 3 radiotherapy. Two patients with negative FDG-PET but positive CT also underwent RPLND. The remaining patients with negative FDG-PET results were followed up. FDG-PET/CT was false positive in one case >3 cm and one <3 cm, in 6 cases >3 cm it was true negative. While FDG-PET can find a viable tumor, there also is an important question of false positive results. It was clinically proven that a negative FDG-PET was correlated with stable disease, but we were unable to examine specimens in these cases.