The clock gene brain and muscle Arnt-like protein-1 (BMAL1) is involved in hair growth.

It is known that baldness caused by androgenetic alopecia is involved with androgen and the androgen receptor. Furthermore, it has been reported that testosterone secretion follows a circadian rhythm. Therefore, we hypothesized that a relationship exists between androgen-induced alopecia and biological rhythm. The mammalian circadian rhythm is controlled by several clock genes. Brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein-1 (BMAL1), one of the clock genes, is a transcription factor that plays central roles in the regulation of circadian rhythms. In this study, we investigated the influence of BMAL1 on hair follicle functions and hair growth. Mice deficient in BMAL1 expression exhibited a delay in hair regrowth after shaving. In hair follicles of mouse vibrissa, expression of Bmal1 and other clock genes was found to be rhythmic. Knockdown of BMAL1 in human follicle dermal papilla cells resulted in modulation of expression of several hair growth-related genes. Therefore, we concluded that expression of clock genes in hair follicles is linked to the circadian rhythm and that BMAL1 can regulate hair growth.

Specific enhancement of vascular endothelial growth factor (VEGF) production in ischemic region by alprostadil--potential therapeutic application in pharmaceutical regenerative medicine.

Alprostadil (lipo-PGE1) is a drug delivery system preparation. This preparation is applied to treat refractory skin ulcers and arteriosclerosis obliterans. We investigated the effects of alprostadil by using the earflap ischemic model. The following results were obtained: 1) Treatment with alprostadil significantly increased the VEGF contents in an ischemic ear; 2) Treatment with alprostadil resulted in strongly expressed VEGF levels only in the ischemic region; 3) Image analysis revealed a significant increase in the number of vessel bypasses and paths after flap creation with alprostadil administration compared to the vehicle-treated ears. The results suggest that it may be possible to apply alprostadil as one device for regenerative medical technology.

Improvement of hind-limb paralysis following traumatic spinal cord injury in rats by grafting normal human keratinocytes: new cell-therapy strategy for nerve regeneration.

Somatic (adult) stem cells are thought to have pluripotency, just as do embryotic stem (ES) cells. We investigated the possibility that grafted epithelial keratinocytes could induce spinal cord regeneration in an animal model of spinal cord injury (SCI). Normal human keratinocytes were cultured by the routine technique, and normal human dermal fibroblasts were cultured by a similar method as a control group. SCI model was prepared by dropping a 10-g weight onto the exposed spinal cord of rats from a height of 25 mm, and 8 days later, the cultured cells were grafted into the injury site. Motor function was significantly improved in the cultured-keratinocyte-grafted group compared with that in the fibroblast-grafted group. After functional observation, human nestin- and nuclei-positive cells were found at the grafted spinal cord. Grafted cultured keratinocytes induced in vitro morphological changes in the neural induction medium. These results indicated one possibility that some of the grafted cultured keratinocytes survived and could have contributed to neural regeneration. On the other hand, it should be noted that the grafted cultured keratinocytes secreted a large amount of enzymes and/or growth factors. Therefore, another possibility is that the grafted-keratinocyte-derived factors could induce survived cell growth and endogenous neural differentiation of spinal-nerve-derived stem cells surrounding the injured spinal cord, leading to functional recovery. Epithelial stem cell therapy may be applied clinically in the near future to treat SCI.

Master equation approach to line shape in dissipative systems.

We propose a formulation to obtain the line shape of a magnetic response with dissipative effects that directly reflects the nature of the environment. Making use of the fact that the time evolution of a response function is described by the same equation as the reduced density operator, we formulate a full description of the complex susceptibility. We describe the dynamics using the equation of motion for the reduced density operator, including the term for the initial correlation between the system and a thermal bath. In this formalism, we treat the full description of non-Markovian dynamics including the initial correlation. We present an explicit and compact formula up to the second order of cumulants, which can be applied in a straightforward way to multiple-spin systems. We also take into account the frequency shift by the system-bath interaction. We study the dependence of the line shape on the type of interaction between the system and the thermal bath. We demonstrate that the present formalism is a powerful tool for investigating various kinds of systems and we show how it is applied to spin systems, including those with up to three spins. We distinguish the contributions of the initial correlation and the frequency shift and make clear the role of each contribution in the Ohmic coupling spectral function. As examples of applications to multispin systems, we obtain the dependence of the line shape on the spatial orientation in relation to the direction of the static field (Nagata-Tazuke effect), including the effects of the thermal environment, in a two-spin system, along with the dependence on the arrangement of a triangle in a three-spin system.

Dynamics of photoexcited states in strongly correlated electron systems.

We theoretically investigate the dynamics of the photoexcited state in the strongly correlated low-dimensional electron systems. In the two-dimensional case, the ultrafast relaxation originating from the transfer of photogenerated charges in the antiferromagnetic background is followed by the slower one originating from the spin structure rearrangement with the new charge distributions. This clearly shows the difference in the relaxation between charge and spin degrees of freedom. In the one-dimensional case, spin-charge separation holds and the mechanical coherence is preserved.