1,25,26-trihydroxyvitamin D3: isolation, identification, and biological activity

A polar metabolite of vitamin D₃ has been produced in vitro from either 1,25-dihydroxyvitamin D₃ incubated with kidney homogenate from vitamin D-supplemented chickens or from 25,26-dihydroxyvitamin D₃ incubated with vitamin D-deficient chicken kidney homogenate. This compound was isolated in pure form and identified as 1,25,26-trihydroxyvitamin D₃ by ultraviolet absorption spectrophotometry and mass spectrometry. Furthermore, its periodate cleavage product comigrates with synthetic 1α-hydroxy-25-keto-27-norvitamin D₃ on high-performance liquid chromatography. The 1,25,26-trihydroxyvitamin D₃ is 0.1-0.01 as active as 1,25-dihydroxyvitamin D₃ in the stimulation of intestinal calcium transport and bone calcium mobilization.     

Ornithine decarboxylase in Phycomyces: In vitro and in vivo properties

The properties of ornithine decarboxylase from Phycomyces blakesleeanus were examined. Enzyme from mycelial cultures was extracted and purified approximately 70-fold. The apparent molecular weight is 96K. The Michaelis constants with respect to ornithine and pyridoxal 5′-phosphate are 90 and 0.37 μm, respectively. Putrescine is a potent competitive inhibitor with a K_i of 75 μm. Exposure of ornithine decarboxylase to sulfhydryl-modifying reagents resulted in a rapid inhibition of activity. In vivo addition of putrescine produced characteristic decreases in cellular ornithine decarboxylase activity. Light stimulation of dark-adapted mycelial cultures also decreased cellular ornithine decarboxylase activity.     

Micro-video study of discontinuous growth of bacterial flagellar filaments in vitro

In a microscope slide preparation, monomeric flagellins were found to polymerize into flagellar filaments spontaneously, without addition of seeds. Dynamic images of individual growing filaments in a dark-field light microscope were recorded throughout their growth by an ultrasensitive video camera. Each filament had its own unique growth curve. The growth curves consisted of two kinds of discrete phase; namely, the elongation and the rest phase. In the former, a filament elongates at a constant rate, fairly similar among all filaments. In the latter, elongation stops completely. Each filament exists in either of the two phases and alternates between them in a stochastic manner. A mean elongation rate of 89 + 15 nm per minute was obtained at the flagellin concentration of 2 mg/ml, for filaments in the elongation phase.     

Spectroscopy and crystal structure of neodymium coordination compound with glycine: Nd2(Gly)6·(ClO4)6·9H2O

Neodymium complex compound with glycine: Nd₂(Gly)₆·(ClO₄₆·9H₂O was synthesized and obtained in the form of monocrystals. Absorption spectra recorded in the region of 8000–35 000 cm^-1 were measured along the crystallographic axes. Intensities of the f-f transitions were analysed on the basis of the Judd theory. The X-ray crystal structure determination of the complex is reported. Crystals are triclinic, space group P$\text{I}$, with a = 11.554(4) Å, b = 14.108(1) Å, c = 15.660(3) Å, α = 97.14(1)°, β = 102.82(2)°, γ = 105.28(1)°, V = 2355.25 ų Z = 2, M.W. = 1495.4, D_c = 2.129)(3) g cm^-3, D^m = 2.103(1) g cm^-3. The structure was solved by Patterson's method and successive Fourier syntheses giving the locations of all nonhydrogen atoms. The final R factor was 0.062 and R_w = 0.073 for 12869 reflections with |F_o| > 5σ|(F_o)|. The asymmetric unit consists of a dimeric formula unit. The coordination polyhedron of Nd atoms comprises seven oxygen atoms from glycine and two from water molecules. The neodymium-glycine bonding mode is compared with that of the calcium-glycine complex.     

Effects of stress on release of dopamine and serotonin in the striatum of spontaneously hypertensive rats: an in vivo voltammetric study

By use of in vivo voltammetry technique, in vivo release of dopamine and serotonin in the striatum under stress was found to be more prominent in spontaneously hypertensive rats (SHR) at 4 weeks of age than in control Wistar-Kyoto rats (WKY). Simultaneously, a greater activation of tyrosine hydroxylase in the striatum was demonstrated in SHR than in WKY. These results indicate that SHR is more susceptible to stress in the central monoaminergic neurons than WKY.     

The structure of U3(O)(OCMe3)10, and unusual trinuclear U(IV) oxo-alkoxide

In an attempt to prepared tetrakis(tert-butoxy)uranium(IV) a trinuclear oxo-alkoxide of uranium(IV) was obtained instead. The compound has the formula U₃O[(CH₃)₃CO]₁₀ and it crystallizes in the hexagonal space group P6₃mc with a = b = 18.256(4) Å, c = 10.013(2) Å, Z = 2. The trinuclear unit is strikingly reminiscent of that in Mo₃O(OCH₂CMe₃)₁₀. In contrast to the molybdenum compound where there is metal-metal bonding, the U?U distance of 3.574(1) Å indicates a non-bonded interaction.     

Fate of Gallium in vivo and its significance in tumour diagnosis and therapy respectively with gallium-67 and cold gallium

Early tumour diagnosis with high quality images is obtained by injecting gallium-67 made free before intravenous administration. No healthy organ uptake of the radionuclide administered in this form takes place. Since free cationic gallium is readily hydrolyzed in aqueous solution, the solution of gallium-67 should be made just before injection from commercial solutions. Both strongly-bound and hydrolyzed gallium-67 concentrate in healthy organs, like liver.Free cold gallium solutions have been successfully used in the treatment of experimental mammary tumour (TGS) in mice.     

New preparations and molecular structures of cis-MCl2(Ph2PCH2PPh2)2, M = Ru,Os and trans-RuCl2(Ph2PCH2PPh2)2

The title compounds were made by reacting bis(diphenylphosphino)methane (dppm) with reduced solutions of OsCl₆^4? and Ru₂OCl₁₀^4?. The crystal and molecular structures of these compounds have been determined form three-dimensional X-ray study. The cis-isomers crystallize with one CHCl₃ per molecule of the complex. All three compounds crystallize in the monoclinic space group P2₁/n with unit cell dimensions as follows: Cis-OsCl₂(dppm)₂·CHCl₃: a = 13.415(4) Å, b = 22.859(4) Å, c = 16.693(3) Å, β = 105.77(3)°, V = 4926(3) ų, Z = 4. cis-RuCl₂(dppm)₂·CHCl₃: a = 13.442(3) Å, b = 22.833(7) Å, c = 16.750(4) Å, β = 105.53(2)°, V = 4953(3) ų, Z = 4. trans-RuCl₂(dppm)₂: a = 11.368(7) Å, b = 10.656(6) Å, c = 18.832(12) Å; β = 103.90(6)°, V = 2213(7) ų; Z = 2. The structures were refined to R = 0.044 (R_w = 0.055) for cis-OsCl₂(dppm)₂·CHCl₃; R = 0.065 (R_w = 0.079) for cis-RuCl₂(dppm)₂·CHCl₃ and R = 0.028 (R_w = 0.038) for trans-RuCl₂(dppm)₂. The complexes are six coordinate with stable four-membered chelate rings. The PMP angle in the chelate rings is ca. 71° in each case.     

Complexes of vitamin B6. XVI. Kinetics and reaction mechanism of iron(III) complexes with pyridoxal-5′-phosphate

The stopped flow technique has been used to study the kinetics of complex formation of iron(III) with pyridoxal-5-phosphate (PLP) in the pH range 1.00–2.50, and in the temperature range 18 °C– 30 °C, at an ionic strength of. 0.50 M (NaCl). From the initial concentration dependence of PLP (T_PLP,) of the reaction rate it can be shown that two kinetic steps can be represented as: k_obs′ = m_i + m_i′_PLP where m_i and m_i′ are pH-dependent parameters. The calculated activation data are δE* = 23.2 ± 1.8 kcal mol^?1 and 10.98 ± 0.53 kcal mol^?1 for the first and second kinetic steps, respectively and δS* are ?20.50 ± 5.96 e.u. and 24.62 ± 1.81 e.u., respeetively.     

Reaction of PtOH complexes with CO2: synthesis and X-ray structure of (PBz3)4Pt2(Ph)2(η1,η1,μ-CO3)·(toluene)

The reaction of (diphoe)Pt(CH₂CN)(OH) and trans-(PBz₃)₂Pt(Ph)(OH) with CO₂ is reported as producing dimeric, bridged carbonato complexes of the type: P₄Pt₂(R)₂(CO₃). The crystal and molecular structure of (PBz₃)₄Pt₂(Ph)₂(μ-CO₃)·(toluene) is also reported, showing η¹, η¹ bonding. The reaction is recognized to proceed in a stepwise fashion through bicarbonato intermediates.     

Large transition metal clusters, 2. Synthesis and properties of Rh55[P(tert-Bu)3]12Cl20

The reaction of a mixture of [(tert-Bu)₃P]₂Rh(H₂)Cl and [(tert-Bu)₃P]₂Rh(CO)Cl with gaseous diborane in benzene solutions at 50–60°C leads to a cluster whose formula is assumed to be Rh₅₅[P(tert-Bu)₃]₁₂Cl₂₀, due to analytical, spectroscopic, and chemical results. The number 55 is one of the ‘magic numbers’ of full shell cuboctahedrons or icosahedrons. ³¹P, and ¹⁰³Rh N.M.R. investigations assign a high mobility either of the ligands or of the rhodium atoms or of both.The coordinatively unsaturated surface of the cluster whose structure is supposed to be cuboctahedral, allows gaseous carbon monoxide to be adsorbed irreversibly, even if the cluster is in the solid state. The CO groups are coordinated exclusively in a terminal manner.     

Crystal structure of nonaquasamarium(III)bromide-l,4-dioxan adduct (1:3:2), Sm(H2O)9·Br3(C4H8O2)2

The title compound has been found to consist of tricapped trigonal prismatic Sm(H₂O)₉³⁺ ions in C_2v symmetry, sandwiched between expanded ‘close packed’ layers of bromide ions, with 1,4-dioxan molecules in chair conformation hydrogen bonding between the equatorial water molecules of adjacent cations.Orthorhombic, Amm2, a = 8.010(3), b = 19.848(4), c = 7.388(3) Å, R = 0.022 for 992 unique reflexions.     

The crystal and molecular structure of [Co(NH3)5PO4]·3H2O,a Na+-K+ ATPase probe

The title compound, Co(NH₃)₅PO₄, prepared by a modified literature procedure, was used to study the inhibition of Na⁺-K⁺ ATPase and to serve as a structural model for ML₄(nucleotide) complexes. The structure was determined by single crystal X-ray diffraction techniques. The crystals are monoclinic, space group P2₁/n, a = 8.638(3), b = 14.517(2), c = 9.145(2) Å, and β = 112.71(2)°. The structure, solved by the heavy atom method to an R value of 3.3% for 1924 reflections, consists of a slightly distorted octahedron with the cobalt bound to the five amines and a monodentate phosphate. Solution structural data is taken from ³¹P NMR measurements. From comparison with other metal phosphate complexes it is concluded that multiple monodentate coordination of a di- or triphosphate closely resembles the coordination of a monophosphate This is based on the similarity of the MO bond angle which is 129.6° in the present example.     

Spectroscopic and magnetic properties of a novel pyrazine-bridged copper(II) chain: [Cu(terpy)(pyz.)](ClO4)2

The [Cu(Terpy)(pyz.)](ClO₄)₂ complex (were Terpy = 2,2′:6′,2′'-terpyridine and pyz. = pyrazine) was synthesized and characterized by means of spectral and magnetic properties. UV-visible and EPR spectra indicate a square pyramidal coordination for the copper(II) ion. Magnetic susceptibility measurements, reported in the temperature range 2–125 K, are analyzed in terms of regular and alternating Heisenberg-chain models giving 2J = ?4.4 K, g = 2.19 (regular chain) and 2J = ?5.6 K, 2J′ = ?1.7 K, g = 2.15 (alternating chain). The better agreement obtained with the alternating-chain model allows us to propose a dimerized zig-zag chain structure with the pyz. ligand bridging the copper(II) ions.