Probing ultrafast spin-relaxation and precession dynamics in a cuprate Mott insulator with seven-femtosecond optical pulses.

A charge excitation in a two-dimensional Mott insulator is strongly coupled with the surrounding spins, which is observed as magnetic-polaron formations of doped carriers and a magnon sideband in the Mott-gap transition spectrum. However, the dynamics related to the spin sector are difficult to measure. Here, we show that pump-probe reflection spectroscopy with seven-femtosecond laser pulses can detect the optically induced spin dynamics in Nd2CuO4, a typical cuprate Mott insulator. The bleaching signal at the Mott-gap transition is enhanced at ~18 fs. This time constant is attributable to the spin-relaxation time during magnetic-polaron formation, which is characterized by the exchange interaction. More importantly, ultrafast coherent oscillations appear in the time evolution of the reflectivity changes, and their frequencies (1400-2700 cm-1) are equal to the probe energy measured from the Mott-gap transition peak. These oscillations can be interpreted as the interference between charge excitations with two magnons originating from charge-spin coupling.

Thrombin promotes fibroblast proliferation during the early stages of experimental radiation pneumonitis.

Huang, L., Ogushi, F., Tani, K., Ogawa, H., Kawano, T., Endo, T., Izumi, K., Ueno, J., Nishitani, H. and Sone, S. Thrombin Promotes Fibroblast Proliferation during the Early Stages of Experimental Radiation Pneumonitis. Radiat. Res. 156, 45-52 (2001). To clarify the role of thrombin in the pathogenesis of radiation-induced pneumonitis, we measured the thrombin activity and fibroblast growth-inducing activity in bronchoalveolar lavage fluid obtained from the irradiated lungs of rats at 1, 2, 4, 8 and 18 weeks after irradiation. Thrombin activity was not detected in the bronchoalveolar lavage fluid from unirradiated rats, but the bronchoalveolar lavage fluid from irradiated rats showed significantly increased thrombin activity which reached a maximum at 4 weeks after treatment. Higher fibroblast growth-inducing activity was detected in the bronchoalveolar lavage fluid from irradiated rats at 4 and 18 weeks than in fluid from unirradiated rats. Bronchoalveolar lavage fluid from irradiated rats that were pretreated with the thrombin inhibitors antithrombin III and argatroban showed significantly inhibited fibroblast growth-inducing activity and thrombin activity at 4 weeks. However, these thrombin inhibitors did not inhibit fibroblast growth-inducing activity in bronchoalveolar lavage fluid from irradiated rats at 18 weeks. Purified rat thrombin similarly induced proliferation of fibroblasts derived from irradiated and unirradiated rats. These findings suggest that thrombin may play an important role as a fibroblast growth-inducing factor during the early stages of radiation pneumonitis.

[The reciprocal pattern of release observed in PRL and TSH following various types of administration of TRH].

Alterations of plasma TSH and PRL levels following various types of administration with TRH were studied in the luteal phase of women with normal menstrual cycles. The results were as follows: Plasma PRL response to a single i.v. injection of tRH with DHEA-S drop injection was not significantly different from that observed without it. The data suggest that DHEA-S does not affect the feedback mechanism in the short-term course of the experiment. Alterations in the plasma levels of PRL during intermittent as well as continuous infusion with TRH were quite different from those with TSH. Plasma TSH increased following the beginning of a continuous infusion with TRH and reached a peak at approximately 180 min, maintaining a plateau until the infusion was withheld. On the other hand, plasma PRL levels increased rapidly to reach peak levels in 30 min after the start of the infusion gradually following a decline in spite of continued TRH stimulation. Furthermore, a stepwise increase of TSH levels was observed following 4 intermittent injections of TRH; however, plasma PRL rapidly reached peak levels in 30 min following the 1st injection of TRH and a further 3 injections did not raise the levels of PRL. The results suggest that in humans, the synthesis and release of PRL occur independently in the pituitary.

[Effect of induced hyperprolactinemia on the plasma levels of C19 steroids in humans].

In order to investigate the relationship between the increment of plasma prolactin (PRL) levels and the change of plasma levels of PRL, DHEA-S, cortisol, aldosterone and 17 alpha OH delta 5-P were quantified by respective RIA in patients treated with TRH parenterally or with sulpiride orally. The results were as follows: During the infusion of TRH, plasma levels of PRL reached the maximal values within 30 min and then declined gradually in spite of continued TRH stimulation. Sulpiride given orally for 12 consecutive days in the luteal phase of the menstrual cycle caused a significant increase in the plasma PRL level. This increase was higher than that obtained in the experiment during the follicular phase. No significant change in the plasma level of 17 alpha OH delta 5-P was observed TRH sulpiride administration. In 3 out of 9 cases, plasma DHEA-S levels were elevated significantly on day 13 to 14 of the experimental course. These results indicate that the responsiveness of plasma levels of adrenal androgens to the raised plasma PRL level requires a certain period of time in the hyperprolactinemic state in the human female.