This article is available online at http://www.jlr.org uct, formed during storage of cholesterol or artifactually produced during work-up of tissue samples ( 1, 2 ). Enzymatic formation of 25-hydroxycholesterol by rat liver mitochondria was described in 1974 ( 3 ), and it was later shown that 25-hydroxycholesterol is formed as a by-product during cholesterol oxidation by the mitochondrial enzyme sterol 27-hydroxylase in liver in pig ( 4 ) and mouse ( 5 ). In addition to the formation of 25-hydroxycholesterol by sterol 27-hydroxylase (CYP27A1), a specifi c human microsomal cholesterol 25-hydroxylase has been cloned and characterized ( 6 ). This enzyme does not belong to the cytochrome P450 family but is related to the eukaryotic stearoyl-CoA desaturases ( 6 ). Low levels (3-5 ng/ml) of 25-hydroxycholesterol are present in human plasma ( 7 ), but the relative contribution of CYP27A1 and cholesterol 25-hydroxylase to its formation is not known.25-Hydroxycholesterol is a potent regulatory oxysterol and may participate in several aspects of lipid metabolism ( 8 ). A family of oxysterol binding proteins with high affi nity for 25-hydroxycholesterol has been identifi ed ( 9 ). Overexpression of oxysterol binding proteins in Chinese hamster ovary cells resulted in signifi cant changes in genes involved in lipid metabolism ( 10 ). Side chain oxidized oxysterols, such as 25-hydroxycholesterol, have been implicated in the regulation of cholesterol homeostasis for a long time but only recently was the mechanism clarifi ed. These oxysterols bind to proteins called Insigs, thereby blocking the sterol regulatory element binding protein signaling that regulates cholesterol biosynthesis ( 11 ). Furthermore, 25-hydroxycholesterol has been shown to activate the nuclear receptor

Abstract. This paper presents a new spectral evolutionary model of galaxies, properly taking the effects of nebular emission and pre-main sequence evolution into account. The impact of these features in different photometric filters is evaluated, along with the influence that variations in the physical conditions of the gas may have on broadband colours, line ratios and equivalent widths. Inclusion of nebular emission is demonstrated to radically change the predicted ultraviolet, optical and near-infrared colours during active star formation. Pre-main sequence evolution is also seen to give a non-negligible contribution to the luminosity in the near-infrared during the first few million years of evolution and should not be omitted when very young systems are being modelled. Finally, we present a comparison of our predictions to observations and two other recent codes of evolutionary synthesis.

The results showed that both hylan B gel and collagen can be safely used for injection treatment of glottal insufficiency. Both treatments resulted in significantly improved voice as rated by the patients. However, the patients treated with hylan B gel showed better vocal fold status and longer maximum phonation time at 12 months after treatment as compared with patients treated with collagen.

No long-term side-effects were found for either the hylan B gel or collagen groups after injection treatment. Both treatments resulted in significantly improved voice as rated by the patients and significantly improved glottal closure. Some resorption was noted for both substances, and approximately 25%, of the patients chose re-treatment 2 years after the initial treatment.

Gravistimulation of tree stems affects wood development by unilaterally inducing wood with modified properties, called reaction wood. Commonly, it also stimulates cambial growth on the reaction wood side. Numerous experiments involving applications of indole-3-acetic acid (IAA) or IAA-transport inhibitors have suggested that reaction wood is induced by a redistribution of IAA around the stem. However, in planta proof for this model is lacking. Therefore, we have mapped endogenous IAA distribution across the cambial region tissues in both aspen (Populus tremula, denoted poplar) and Scots pine (Pinus sylvestris) trees forming reaction wood, using tangential cryosectioning combined with sensitive gas chromatographymass spectrometry analysis. Moreover, we have documented the kinetics of IAA during reaction wood induction in these species. Our analysis of endogenous IAA demonstrates that reaction wood is formed without any obvious alterations in IAA balance. This is in contrast to gravitropic responses in roots and shoots where a redistribution of IAA has been documented. It is also of interest that cambial growth on the tension wood side was stimulated without an increase in IAA. Taken together, our results suggest a role for signals other than IAA in the reaction wood response, or that the gravitational stimulus interacts with the IAA signal transduction pathway.Displacement of stems and branches by wind or mechanical stress in woody species results in the formation of reaction wood. This response is unilateral and beneficial for the tree in that it creates physical strains in the wood that force the stem or branch back toward its original orientation in space (Scurfield, 1973;Wilson and Archer, 1977;Timell, 1986). Angiosperm and gymnosperm trees differ in their nature of reaction wood. In angiosperm trees, such as poplar, reaction wood is called tension wood and forms on the upper side of stems that have been displaced. Tension wood characteristically has few, small vessels, and fibers with an inner gelatinous cell wall layer (the G-layer) that consists of almost pure cellulose with microfibrils that are parallel to the long cell axis (Haygreen and Bowyer, 1996;Jourez et al., 2001). In gymnosperm trees, such as pine, reaction wood is called compression wood and forms at the lower side of displaced stems. Compression wood is characterized by short, rounded tracheids that have thick walls with increased lignin content and increased microfibril angles (Timell, 1969). The formation of reaction wood is often (but not always) accompanied by a stimulation of cambial cell division, whereas the cell division at the opposite side is more or less inhibited.The physiology and development of reaction wood formation has been extensively explored (particularly in gymnosperms) and reviewed in great detail by Timell (1986). The induction of reaction wood by gravistimuli rather than by mechanical stimulation has been deduced from a large number of bending, leaning, and clinostat experiments. Reaction wood can also be induced by int...