Role of structural relaxations and vibrational excitations in the high-frequency dynamics of liquids and glasses

We present theoretical investigation on the high-frequency collective dynamics in liquids and glasses at microscopic length scales and terahertz frequency region based on the mode-coupling theory for ideal liquid-glass transition. We focus on recently investigated issues from inelastic-X-ray-scattering and computer-simulation studies for dynamic structure factors and longitudinal and transversal current spectra: the anomalous dispersion of the high-frequency sound velocity and the nature of the low-frequency excitation called the boson peak. It will be discussed how the sound mode interferes with other low-lying modes present in the system. Thereby, we provide a systematic explanation of the anomalous sound-velocity dispersion in systems -- ranging from high temperature liquid down to deep inside the glass state -- in terms of the contributions from the structural-relaxation processes and from vibrational excitations called the anomalous-oscillation peak (AOP). A possibility of observing negative dispersion -- the {\em decrease} of the sound velocity upon increase of the wave number -- is argued when the sound-velocity dispersion is dominated by the contribution from the vibrational dynamics. We also show that the low-frequency excitation, observable in both of the glass-state longitudinal and transversal current spectra at the same resonance frequency, is the manifestation of the AOP. As a consequence of the presence of the AOP in the transversal current spectra, it is predicted that the transversal sound velocity also exhibits the anomalous dispersion. These results of the theory are demonstrated for a model of the Lennard-Jones system.Comment: 25 pages, 22 figure

Anti-tumor activity of murine peritoneal macrophages induced by porcine skin gelatin

Aim: To study the induction of anti-tumor activity of murine peritoneal macrophages in vitro by porcine skin gelatin. Methods: Anti-tumor activity of the macrophages was evaluated with tritium thymidine uptake by target tumor cells. ELISA was used to measure amounts of cytokines secreted in culture medium. Results: The ability of the gelatin to induce anti-tumor activity of the macrophages was stronger than that of lipopolysaccharide of E. coli. Combination of the lipopolysaccharide and interferon-g synergistically stimulated the macrophages but that of the gelatin and interferon-g additionally did. The culture supernatant of the macrophages incubated with the gelatin also showed higher anti-tumor activity than that with the lipopolysaccharide though the lipopolysaccharide was more excellent than the gelatin in stimulating secretion of anti-tumor cytokines (IL-1, IL-6, TNF-a, IFN-g) by the macrophages. Anti-TNF-a antibody partially suppressed the anti-tumor activity of the culture supernatant of the macrophages incubated with the lipopolysaccharide but not with the gelatin. The gelatin induced anti-tumor activity of the macrophages of C3H/HeJ as well as C3H/HeN mice whereas the lipopolysaccharide did only in C3H/HeN mice. The macrophages stimulated in vitro by the gelatin exerted anti-tumor activity in vivo. Moreover, the gelatin stimulated peritoneal exudates cells in vivo when subcutaneously administered with them. Conclusions: Porcine skin gelatin induces anti-tumor activity of macrophages in mice and its magnitude is greater than that of lipopolysaccharide of E. coli. Its mechanism is different from that of the lipopolysaccharide but not fully clarified.Цель: изучить in vitro противоопухолевую активность мышиных перитонеальных макрофагов, индуцированную желатином кожи свиньи. Методы: противоопухолевую активность макрофагов оценивали по включению меченного тимидина опухолевыми клетками-мишенями. Уровень цитокинов, секретируемых в культуральную среду, определяли с помощью ELISA. Результаты: cпособность желатина индуцировать противоопухолевую активность макрофагов была сильнее, чем у липополисахарида E. coli. Комбинация липополисахарида и интерферона-γ (IFN-γ) синергично стимулировала макрофаги, что показано и для комбинации желатина с IFN-γ. Противоопухолевая активность культурального супернатанта макрофагов, инкубированных с желатином, была выше, чем в случае применения липополисахарида, хотя липополисахарид индуцировал более сильную секрецию противоопухолевых цитокинов (IL-1, IL-6, TNF-α, IFN-γ) макрофагами. Антитела против TNF-α частично угнетали противоопухолевую активность культурального супернатанта макрофагов, инкубированных с липополисахаридом, но не с желатином. Желатин индуцировал противоопухолевую активность макрофагов как C3H/HeJ мышей, так и мышей C3H/ HeN, в то время как липополисахарид влиял только на макрофаги C3H/HeN мышей. Макрофаги, стимулированные in vitro, показывали противоопухолевую активность in vivo. Более того, желатин стимулировал клетки перитонеального экссудата in vivo при одновременном подкожном введении. Выводы: желатин свиной кожи индуцирует противоопухолевую активность макрофагов у мышей, причем более эффективно, чем липополисахарид E. coli. Механизм действия желатина отличается от механизма действия липополисахарида и остается пока невыясненным до конц

Serum factors that suppress cytotoxic effect of methotrexate

To study the phenomenon that human erythroid leukemia K-562 cells are more sensitive to cytotoxic effect of antimetabolites when cultured in a serum-free medium than in a conventional medium containing fetal calf serum (FCS). Methods: Cytotoxic effects of methotrexate, azaserine and 5-fluorouracil were estimated by accessing the lactate dehydrogenase (LDH) activity of viable tumor cells. Proteins of FCS were separated using two-dimensional electrophoresis followed by mass spectrometry analysis. Results: Addition of 10% FCS attenuated anti-tumor activity of methotrexate and azaserine against K-562 cells compared with serum-free medium. Such an activity of FCS was different for each serum lot. Comparison of the proteins in active serum lot with those in not active one using two-dimensional electrophoresis showed that in the active serum there were proteins 150 kDa, which were absent in the not active serum lot. Mass spectrometry indicated that all those proteins had the amino acid sequence of albumin. Sera of one healthy volunteer and two patients with thyroid cancer also attenuated the activity of the agent. Conclusion: Several lots of FCS and human serum demonstrated the ability to attenuate the cytotoxic effect of methotrexate in vitro, possibly due to the formation of albumin dimers/MTX complexes

In VIVO anti-tumor activities of gelatin

Aim: As reported previously, porcine skin gelatin exerted direct anti-tumor effect in vitro and induced anti-tumor peritoneal macrophages in vitro. The present study investigated whether or not the gelatin exerted anti-tumor effect in vivo. Methods: In vitro anti-tumor activities of peritoneal macrophages and the gelatin were evaluated with tritium thymidine uptake by target tumor cells. In vivo anti-tumor activity was evaluated with the survival of tumor-bearing animals and the size of the tumor. Results: Intraperitoneal daily administration of 12.5 mg of the gelatin prolonged the survival of mice which had been intraperitoneally inoculated with MH134 (hepatic cell carcinoma cell line) or Colon 26 (colon carcinoma cell line) tumor cells, and there were no tumors in case of MH134 cells inoculation. Intraperitoneal daily administration of 12.5 mg of the gelatin did not affect growth of subcutaneous MH134 tumor. The gelatin administered subcutaneously did not affect the survival of mice with intraperitoneal MH134 tumor. On the other hand, bovine skin gelatin administered subcutaneously achieved statistically significant prolongation of the survival. The contact of MH134 cells with porcine skin gelatin for 5 min was required for the gelatin to exert its anti-tumor activity in vitro. Porcine skin gelatin of 12.5 mg injected intraperitoneally was detected as protein in the peritoneal cavity 5 min after the injection. Peritoneal macrophages elicited by intraperitoneal injection with porcine skin gelatin suppressed tritium thymidine uptake by MH134 cells more strongly than those elicited by thioglycollate injection. Conclusion: Porcine skin gelatin administered intraperitoneally prolonged the survival of tumor-bearing mice via activation of peritoneal macrophages and involvement of direct anti-tumor activity of porcine skin gelatin. Key Words: porcine skin, gelatin, dissemination

Observation of the onset of strong scattering on high frequency acoustic phonons in densified silica glass

The linewidth of longitudinal acoustic waves in densified silica glass is obtained by inelastic x-ray scattering. It increases with a high power alpha of the frequency up to a crossover where the waves experience strong scattering. We find that \alpha is at least 4, and probably larger. Resonance and hybridization of acoustic waves with the boson-peak modes seems to be a more likely explanation for these findings than Rayleigh scattering from disorder.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Letter