Induction of lymphokine-activated killer activity in rat splenocyte cultures: The importance of 2-mercaptoethanol and indomethacin

The role of 2-mercaptoethanol and indomethacin in the induction of lymphokine-activated killer (LAK) activity by interleukin-2 (IL-2) in rat splenocyte cultures was investigated. Spleens from 4-month-old male rats of five different strains were tested. Splenocytes were cultured for 3-5 days in the presence of IL-2 (1000 U/ml) and LAK activity was assessed by 4-h51Cr release assays with P815 and YAC-1 cells as targets. LAK activity could be induced by IL-2 in splenocytes from all rat strains, but only when 2-mercaptoethanol was present in the culture medium. Optimal LAK activity was induced when the 2-mercaptoethanol concentration in splenocyte cultures was at least 5 μM. Different rat strains showed differences in levels of in vitro induction of LAK activity. In the presence of 2-mercaptoethanol the level of LAK activity induced by IL-2 was high in BN and Lewis rats, intermediate in Wistar and Wag rats, and low in DZB rats. In the absence of 2-mercaptoethanol no or minimal LAK activity was induced. Furthermore we observed that addition of 50 μm indomethacin to the culture medium in the presence of 2-mercaptoethanol augmented the induction of LAK activity to some extent. In the absence of 2-mercaptoethanol, addition of indomethacin resulted only in low levels or no induction of LAK activity. We conclude that for optimal induction of LAK activity by IL-2 in rat splenocyte cultures 2-mercaptoethanol is essential, while indomethacin can only marginally further improve this induction

The relationships between microstructure and crystal structure in zincite solid solutions

Single phase (Zn,Fe)(1-x) O zincite solid solution samples have been prepared by high temperature equilibration in air and in reducing atmospheres, followed by quenching to room temperature. The Fe2+/Fe3+ concentrations in the samples have been determined using wet chemical and XPS techniques. Iron is found to be present in zincite predominantly in the form of Fe3+ ions. The transition from an equiaxed grain morphology to plate-like zincite crystals is shown to be associated with increasing Fe3+ concentration, increasing elongation in of the hexagonal crystals and increasing anisotropic strain along the c-axis. The plate-like crystals are shown to contain planar defects and zincite polytypes at high iron concentrations

Thermal expansion of coesite determined by synchrotron powder X-ray diffraction

Thermal expansion of synthetic coesite was studied with synchrotron powder X-ray diffraction in the temperature range of 100–1000 K. We determined the unit cell parameters of monoclinic coesite (a, b, c, and β) every 50 K in this temperature range. We observed that a and b parameters increase with increasing temperature, while c decreases. The β angle also decreases with temperature and approaches 120°. As a result, the unit cell volume expands by only 0.7% in this temperature range. Our measurements provide thermal expansion coefficients of coesite as a function of temperature: it increases from 3.4 × 10$^{−6}$ K$^{−1}$ at 100 K to 9.3 × 10$^{−6}$ K$^{−1}$ at 600 K and remains nearly constant above this temperature. The Suzuki model based on the zero-pressure Mie–Grüneisen equation of state was implemented to fit the unit cell volume data. The refined parameters are V$_0$ = 546.30(2) Å$^3$, Q = 7.20(12) × 10$^6$ J/mol and $θ_D$ = 1018(43) K, where $θ_D$ is the Debye temperature and V0 is the unit cell volume at 0 K with an assumption that K′ is equal to 1.8. The obtained Debye temperature is consistent with that determined in a previous study for heat capacity measurements