Characterization and comparison of hydrophilic and hydrophobic room temperature ionic liquids incorporating the imidazolium cation

I read this book the same weekend that the Packers took on the Rams, and the experience of the latter event, obviously, colored my judgment. Although I abhor anything that smacks of being a handbook (like, \"How to Earn a Merit Badge in Neurosurgery\") because too many volumes in biomedical science already evince a boyscout-like approach, I must confess that parts of this volume are fast, scholarly, and significant, with certain reservations. I like parts of this well-illustrated book because Dr. Sj6strand, without so stating, develops certain subjects on technique in relation to the acquisition of judgment and sophistication. And this is important! So, given that the author (like all of us) is somewhat deficient in some areas, and biased in others, the book is still valuable if the uninitiated reader swallows it in a general fashion, realizing full well that what will be required from the reader is a modulation to fit his vision, propreception, adaptation and response, and the kind of problem he is undertaking. A major deficiency of this book is revealed by comparison of its use of physics and of chemistry to provide understanding and background for the application of high resolution electron microscopy to problems in biology. Since the volume is keyed to high resolution electron microscopy, which is a sophisticated form of structural analysis, but really morphology in a modern guise, the physical and mechanical background of The instrument and its ancillary tools are simply and well presented. The potential use of chemical or cytochemical information as it relates to biological fine structure , however, is quite deficient. I wonder when even sophisticated morphol-ogists will consider fixation a reaction and not a technique; only then will the fundamentals become self-evident and predictable and this sine qua flon will become less mystical. Staining reactions (the most inadequate chapter) ought to be something more than a technique to selectively enhance contrast of morphological elements; it ought to give the structural addresses of some of the chemical residents of cell components. Is it pertinent that auto-radiography gets singled out for more complete coverage than other significant aspects of cytochemistry by a high resolution microscopist, when it has a built-in minimal error of 1,000 A in standard practice? I don't mean to blind-side (in strict football terminology) Dr. Sj6strand's efforts for what is \"routinely used in our laboratory\"; what is done is usually well done. It's just that …

Methods in Enzymology.

The vitamin D endocrine system is essential for calcium and bone homeostasis. The precise mode of action and the full spectrum of activities of the vitamin D hormone, 1,25-dihydroxyvitamin D [1,25-(OH)2D], can now be better evaluated by critical analysis of mice with engineered deletion of the vitamin D receptor (VDR). Absence of a functional VDR or the key activating enzyme, 25-OHD-1α-hydroxylase (CYP27B1), in mice creates a bone and growth plate phenotype that mimics humans with the same congenital disease or severe vitamin D deficiency. The intestine is the key target for the VDR because high calcium intake, or selective VDR rescue in the intestine, restores a normal bone and growth plate phenotype.

The VDR is nearly ubiquitously expressed, and almost all cells respond to 1,25-(OH)2D exposure; about 3% of the mouse or human genome is regulated, directly and/or indirectly, by the vitamin D endocrine system, suggesting a more widespread function. VDR-deficient mice, but not vitamin D- or 1α-hydroxylase-deficient mice, and man develop total alopecia, indicating that the function of the VDR and its ligand is not fully overlapping. The immune system of VDR- or vitamin D-deficient mice is grossly normal but shows increased sensitivity to autoimmune diseases such as inflammatory bowel disease or type 1 diabetes after exposure to predisposing factors. VDR-deficient mice do not have a spontaneous increase in cancer but are more prone to oncogene- or chemocarcinogen-induced tumors. They also develop high renin hypertension, cardiac hypertrophy, and increased thrombogenicity. Vitamin D deficiency in humans is associated with increased prevalence of diseases, as predicted by the VDR null phenotype. Prospective vitamin D supplementation studies with multiple noncalcemic endpoints are needed to define the benefits of an optimal vitamin D status.

Vitamin D and Human Health: Lessons from Vitamin D Receptor Null Mice

Environmental fate and toxicity of ionic liquids: a review.

1,25-Dihydroxvitamin D3 [1,25(OH)2D3] is the hormonally active form of vitamin D. The genomic mechanism of 1,25(OH)2D3 action involves the direct binding of the 1,25(OH)2D3 activated vitamin D receptor/retinoic X receptor (VDR/RXR) heterodimeric complex to specific DNA sequences. Numerous VDR co-regulatory proteins have been identified, and genome-wide studies have shown that the actions of 1,25(OH)2D3 involve regulation of gene activity at a range of locations many kilobases from the transcription start site. The structure of the liganded VDR/RXR complex was recently characterized using cryoelectron microscopy, X-ray scattering, and hydrogen deuterium exchange. These recent technological advances will result in a more complete understanding of VDR coactivator interactions, thus facilitating cell and gene specific clinical applications. Although the identification of mechanisms mediating VDR-regulated transcription has been one focus of recent research in the field, other topics of fundamental importance include the identification and functional significance of proteins involved in the metabolism of vitamin D. CYP2R1 has been identified as the most important 25-hydroxylase, and a critical role for CYP24A1 in humans was noted in studies showing that inactivating mutations in CYP24A1 are a probable cause of idiopathic infantile hypercalcemia. In addition, studies using knockout and transgenic mice have provided new insight on the physiological role of vitamin D in classical target tissues as well as evidence of extraskeletal effects of 1,25(OH)2D3 including inhibition of cancer progression, effects on the cardiovascular system, and immunomodulatory effects in certain autoimmune diseases. Some of the mechanistic findings in mouse models have also been observed in humans. The identification of similar pathways in humans could lead to the development of new therapies to prevent and treat disease.

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Vitamin D: Metabolism, Molecular Mechanism of Action, and Pleiotropic Effects.

The three-dimensional structures of the truncated myosin head from Dictyostelium discoideum myosin II (S1dC) complexed with MgAMPPNP, MgATPγS, and MgADP are reported at 2.1, 1.9, and 2.1 A resolution, respectively. Crystals were obtained by cocrystallization and were isomorphous with respect to those of S1dC·MgADP·BeFx [Fisher, A. J., et al. (1995) Biochemistry 34, 8960−8972]. In all three structures, the electron density for the entire nucleotide was clearly discernible. The overall structures of all three complexes are very similar to that of the beryllium fluoride complex which suggests that the differences in the physiological effects of ATPγS and AMPPNP are due to the changes in the equilibrium between the actin-bound and actin-free states of myosin caused by the lower affinity of AMPPNP for myosin. In S1dC·MgAMPPNP, the presence of the bridging nitrogen prompts the side chain of Asn233 to rotate which disrupts the hydrogen bonding pattern in the nucleotide binding pocket and alters the water structu...

/pdf/x-ray-structures-of-the-mgadp-mgatpgammas-and-mgamppnp-2ur2xi7ckh.pdf

X-ray structures of the MgADP, MgATPgammaS, and MgAMPPNP complexes of the Dictyostelium discoideum myosin motor domain.

We have determined the crystal structures of the ligand binding domain (LBD) of the rat vitamin D receptor in ternary complexes with a synthetic LXXLL-containing peptide and the following four ligands:  1α,25-dihydroxyvitamin D3; 2-methylene-19-nor-(20S)-1α,25-dihydroxyvitamin D3 (2MD); 1α-hydroxy-2-methylene-19-nor-(20S)-bishomopregnacalciferol (2MbisP), and 2α-methyl-19-nor-1α,25-dihydroxyvitamin D3 (2AM20R). The conformation of the LBD is identical in each complex. Binding of the 2-carbon-modified analogues does not change the positions of the amino acids in the ligand binding site and has no effect on the interactions in the coactivator binding pocket. The CD ring of the superpotent analogue, 2MD, is tilted within the binding site relative to the other ligands in this study and to (20S)-1α,25-dihydroxyvitamin D3 [Tocchini-Valentini et al. (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 5491−5496]. The aliphatic side chain of 2MD follows a different path within the binding site; nevertheless, the 25-hydroxyl ...

Molecular structure of the rat vitamin D receptor ligand binding domain complexed with 2-carbon-substituted vitamin D3 hormone analogues and a LXXLL-containing coactivator peptide.

Metal ion separations in polyethylene glycol-based aqueous biphasic systems: correlation of partitioning behavior with available thermodynamic hydration data

https://biochem.wisc.edu/sites/default/files/labs/holden/pdfs/97Bauer_et_al_2000.pdf

X-ray structures of the apo and MgATP-bound states of Dictyostelium discoideum myosin motor domain.

Solvent extraction, utilizing an oil/water mixture (e.g., chloroform/water) and a suitable complexant, is a proven technology for the selective removal and recovery of metal ions from aqueous solutions.1,2 Solving the increasing number of metal ion separation problems has typically focused on finding an appropriate selective extractant, making it as lipophilic as possible, and determining the best diluent. This has often meant the use of expensive extractants and volatile, toxic, organic diluents. In addition, the extracted species is usually dehydrated and partitioned as an ion pair. Whole classes of water soluble extractants cannot be utilized in these systems.

Cary B. Bauer

Papers

X-ray structures of the MgADP, MgATPgammaS, and MgAMPPNP complexes of the Dictyostelium discoideum myosin motor domain.

Molecular structure of the rat vitamin D receptor ligand binding domain complexed with 2-carbon-substituted vitamin D3 hormone analogues and a LXXLL-containing coactivator peptide.

Metal ion separations in polyethylene glycol-based aqueous biphasic systems: correlation of partitioning behavior with available thermodynamic hydration data

X-ray structures of the apo and MgATP-bound states of Dictyostelium discoideum myosin motor domain.

Metal Ion Separations in Polyethylene Glycol-Based Aqueous Biphasic Systems