Dynamics of ligand substitution in labile cobalt complexes resolved by ultrafast T-jump

Ligand exchange of hydrated metal complexes is common in chemical and biological systems. Using the ultrafast T-jump, we examined this process, specifically the transformation of aqua cobalt (II) complexes to their fully halogenated species. The results reveal a stepwise mechanism with time scales varying from hundreds of picoseconds to nanoseconds. The dynamics are significantly faster when the structure is retained but becomes rate-limited when the octahedral-to-tetrahedral structural change bottlenecks the transformation. Evidence is presented, from bimolecular kinetics and energetics (enthalpic and entropic), for a reaction in which the ligand assists the displacement of water molecules, with the retention of the entering ligand in the activated state. The reaction time scale deviates by one to two orders of magnitude from that of ionic diffusion, suggesting the involvement of a collisional barrier between the ion and the much larger complex

CD8 and CD45RO T lymphocytes in bone marrow of gastric cancer patients: correlation with disseminated tumor cells and disease outcome

Aim: To evaluate the association between the presence of CD8 and CD45RO T lymphocytes in bone marrow (BM), disseminated tumor cells (DTCs), tumor hypoxia and their impact on disease outcome. Material and methods: 91 naïve gastric cancer (GC) patients were enrolled into the study. DTCs, CD8- and CD45RO-positive T lymphocytes in BM were detected using immunocytochemistry. All patients were thoroughly informed about the study that was approved by the local ethics committee. Statistical analyses were done using NCSS2000/PASS2000 and Prism, version 4.03 software packages. Results: It was detected that 80.5 and 81.3% of patients had CD8- and CD45RO-positive T cells in BM, respectively. When DTCs were detected in BM, the number of patients with CD8-and CD45RO-positive T cells in BM were 86.1 and 84.4%, respectively. It was also determined that the number of patients with DTCs in BM with categories M0 and M1 and with CD8- and CD45RO-positive T cells in BM were 86.2 and 85.7%, 85.7 and 80.0%, respectively. The association between DTCs in BM and presence of CD8 and CD45RO T cells lymphocytes in BM was not found. At the same time it was shown the association between presence of CD8 and CD45RO T lymphocytes and survival. The presence of CD8- and CD45RO-positive T cells in BM were accompanied with significantly longer overall survival of patients compared to that of patients without CD8- and CD45RO-positive T cells in BM. Conclusion: Patients with the presence of CD8- and CD45RO-posi­tive T cells in BM demonstrated better survival of GC patients than those with the absence of these cells in BM. It may be suggested that tumor cells in BM are controlled in a dormant state by T cells in BM, in particular by CD8-positive T cells. Key Words: CD8 T lymphocytes, CD45RO T lymphocytes, bone marrow, disseminated tumor cells, tumor hypoxia, survival

Bioenergetic status and hypoxia in Lewis lung carcinoma assessed by 31P NMR spectroscopy: correlation with tumor progression

Aim: Тo evaluate the hypoxia level and some indices of Lewis lung carcinoma energy metabolism by means of 31Р NMR spectroscopy in perchloric acid (PCA) tissue extracts during growth of primary tumor and metastasis. Мaterials and Methods: C57Bl/6 mice-bearing Lewis lung carcinoma were used in this study. Tumor energy metabolism was studied by 31P NMR spectroscopy and the metabolic NMR ratios were used as parameters for metabolic status and hypoxia level. Results: It was shown that growth of primary tumor is accompanied with increase of Pi/PCr, Pi/bNТP and PME/bNТP ratios that reflect drop of tumor energy status and oxygenation level in tumor tissue. These changes in relevant metabolic ratios correlate with enlargement of primary tumor volume (r = 0.87, p = 0.0045; r = 0.90, p = 0.0012; r = 0.764, p = 0.05, respectively) as well as with the number of lung metastases (rs = 0.761, p = 0.028; rs = 0.86, p = 0.0049; rs = 0.77, p = 0.040, respectively). Conclusion: In present study it was shown that 31Р NMR spectroscopy of PCA tumor tissue extracts may be used as reliable method for the assessment of the level of oxygenation as well as changes in energy metabolism in the experimental tumors. It may be helpful to evaluate the energy status of human tumors by investigation both of biopsy and surgical specimens. Hypoxia and hypoxia-associated metabolic events in primary tumor are linked with malignant progression, in particular metastasis.Цель: определить уровень гипоксии и некоторые показатели энергетического метаболизма карциномы легкого Льюис с помощью 31Р ЯМР-спектроскопии перхлорных (РСА) экстрактов ткани в процессе роста первичной опухоли и ее метастазировании. Мaтериалы и методы: использовали в исследовании мышей C57Bl/6 с перевивной карциномой легкого Льюис. Энергетический метаболизм опухоли изучали с помощью ЯМР спектроскопии, oтношения фосфорсодержащих метаболитов использовали в качестве параметров метаболического статуса и уровня гипоксии. Результаты: установлено, что рост первичной опухоли сопровождается увеличением соотношений Pi/PCr, Pi/βNТP and PME/βNТP в опухоли, что отражает снижение уровня биоэнергетического статуса и уровня оксигенации в опухоли. Эти изменения соотношений важных метаболических показателей коррелируют с увеличением объема первичной опухоли (r = 0,87, p = 0,0045; r = 0,90, p = 0,0012; r = 0,764, p = 0,05 соответственно) и количеством метатазов в легких (rs = 0,761, p = 0,028; rs = 0,86, p = 0,0049; rs = 0,77, p = 0,040 соответственно). Выводы: установлено, что 31Р ЯМР-спектроскопия PCA тканевых экстрактов может быть надежным методом оценки уровня оксигенации и биоэнергетического статуса экспериментальных опухолей. Этот метод может быть полезным при оценке энергетического метаболизма опухолей человека, в частности при исследовании биопсийного и операционного материала. Гипоксия и гипоксия-ассоциированные изменения метаболизма в первичной опухоли связаны со злокачественной прогрессией, в частности с метастазированием

Yellow luminescence in ZnO layers grown on sapphire

We conducted a detailed study of the yellow luminescence (YL) band that has a maximum of 2.19eV at 10K in undoped and N-doped ZnO layers grown on sapphire substrates. Important characteristics of this band and the related defect are established. The YL band is attributed to a transition between a shallow donor and an acceptor with an energy level ∼0.4eV above the valence band. Quenching of the YL intensity with activation energies of 85meV and 0.4eV is observed at temperatures above 100 and 320K, respectively. The YL band is possibly due to a defect complex that may include a Znvacancy

Direct simulation Monte Carlo for new regimes in aggregation-fragmentation kinetics

We revisit two basic Direct Simulation Monte Carlo Methods to model aggregation kinetics and extend them for aggregation processes with collisional fragmentation (shattering). We test the performance and accuracy of the extended methods and compare their performance with efficient deterministic finite-difference method applied to the same model. We validate the stochastic methods on the test problems and apply them to verify the existence of oscillating regimes in the aggregation-fragmentation kinetics recently detected in deterministic simulations. We confirm the emergence of steady oscillations of densities in such systems and prove the stability of the oscillations with respect to fluctuations and noise.Comment: 19 pages, 2 figures, 4 table

Nanohyperthermia of malignant tumors. II. In vivo tumor heating with manganese perovskite nanoparticles

Objectives: To evaluate the ability of manganese perovskite nanoparticles (lanthanum-strontium manganite) to heat the tumor tissue in vivo under action of external alternating magnetic field. Materials and Methods: The magnetic fluid on the basis of nanoparticles of perovskite manganite was tested in the heating experiments using of alternating magnetic field of frequency 300 kHz and amplitude 7.7 kA/m. Guerin carcinoma was transplanted into the muscle of rat. Magnetic fluid was injected intramuscularly or intratumorally. Temperature was measured by copper-constantan thermocouple. Results: Temperature of magnetic fluid was increased by 56 °C for 10 min of alternating magnetic field action. Administration of magnetic fluid into the muscle followed by alternating magnetic field resulted in the elevation of muscle temperature by 8 °C after 30 min post injection. Temperature of the tumor injected with magnetic fluid and treated by alternating magnetic field was increased by 13.6 °C on the 30 min of combined influence. Conclusion: In vivo study with rat tissue has demonstrated that magnetic fluid of manganite perovskite injected in the tumor increases the tumor temperature under an alternating magnetic field. Obtained results emphasize that magnetic fluid of manganite perovskite can be considered as effective inducer of tumor hyperthermia

Nanohyperthermia of malignant tumors.i. lanthanum-strontium manganite magnetic fluid as potential inducer of tumor hyperthermia

Objectives: To synthesize magnetic particles of lanthanum-strontium manganite, prepare the magnetic fluid (MF), evaluate the generation of heat by particles and determine their common toxiсity. Methods: Nanoparticles based on the solid solutions of lanthanum-strontium manganite (La1-xSrxMnO3) have been synthesized by a sol-gel method. Conventional methods of experimental oncology were used. Results: Nanoparticles of ferromagnetic materials on the basis of solid solutions of lanthanum strontium manganite by sol-gel method were synthesized. It was shown the possibility to regulate the aggregate form of particles that are formed during the synthesis. Magnetic fluid based on the synthesized nanoparticles and water solutions of agarose have been produced. It was shown the possibility to heat this magnetic fluid up to 42–45 °С in externally applied alternating magnetic field (AMF) operated at 100–400 kHz. It was determined that under long-term influence of AMF nanofluid is heated up to temperature which is not over that of magnetic phase transition. It was detected that magnetic powder as well as fluid have not displayed acute toxicity or side effects (intraperitoneal or intratumoral administration) in animals either intact or with transplanted tumors. Conclusions: Possibility of synthesized magnetic fluid to generate heat in externally applied AMF as well as lack of side effects allow to consider its as a potential mean for tumor hyperthermia (HT)

Correlations between spatially resolved Raman shifts and dislocation density in GaN films

Spatially resolved Raman spectra were measured on thick GaN samples with known dislocation density grown by hydride vapor phase epitaxy. The frequencies of the E-2 (high) and E-1 (transverse optical) phonons shift to lower wave number over a distance of 30 mum from the sapphire substrate/GaN interface. The shifts are linearly correlated with the dislocation density suggesting that the strain due to the lattice mismatch at the interface determines both quantities

Electron beam and optical depth profiling of quasibulk GaN

Electron beam and optical depth profiling of thick (5.5-64 mu m) quasibulk n-type GaN samples, grown by hydride vapor-phase epitaxy, were carried out using electron beam induced current (EBIC), microphotoluminescence (PL), and transmission electron microscopy (TEM). The minority carrier diffusion length, L, was found to increase linearly from 0.25 mu m, at a distance of about 5 mu m from the GaN/sapphire interface, to 0.63 mu m at the GaN surface, for a 36-mu m-thick sample. The increase in L was accompanied by a corresponding increase in PL band-to-band radiative transition intensity as a function of distance from the GaN/sapphire interface. We attribute the latter changes in PL intensity and minority carrier diffusion length to a reduced carrier mobility and lifetime at the interface, due to scattering at threading dislocations. The results of EBIC and PL measurements are in good agreement with the values for dislocation density obtained using TEM