Activation by adenosine triphosphate in the phosphorylation kinetics of sodium and potassium ion transport adenosine triphosphatase.
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Adenosine Triphosphatases↗
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Results for “Lithium Compounds”
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Inhibitors of sterol synthesis. Synthesis and spectral properties of 3 beta-hydroxy-25,26,26,26,27,27,27-heptafluoro-5 alpha-cholestan-15-one.
3 beta-Hydroxy-25,26,26,26,27,27,27-heptafluoro-5 alpha-cholestan-15-one (4) has been prepared as part of a program to synthesize 15-ketosterols that are not readily metabolized to cholesterol or side-chain oxygenated species. Saponification of 3 beta-acetoxy-5 alpha-chola-8(14),23-dien-15-one (5) followed by lithium-ammonia reduction with a bromobenzene quench gave 3 beta-hydroxy-5 alpha-chol-23-en-15-one (6). Addition of (CF3)2CFI to 6 in the presence of triethylborane gave an iodide preparation, which was reduced to 4 with tributyltin hydride (71% overall yield of 4 from 5). The 23-iodide preparations consisted of 6:1 mixtures of (23R)-3 beta-hydroxy-23-iodo-25,26,26,26,27,27,27-heptafluoro-5 alpha-cholestan-15-one (9a) and its C-23 epimer 9b with variable amounts of 4. Compound 4 was also prepared by lithium-ammonia reduction of the delta 8(14) analogs of 4 and iodides 9a and 9b. The presence of small amounts of 6 in the latter product suggested a side reaction involving cleavage of the C24-C25 bond with loss of a (CF3)2CF radical. Also prepared were 25,26,26,26,27,27,27-heptafluoro-5 alpha-cholestane-3 beta, 15 alpha-diol, its 15 beta epimer, the 7 alpha-methyl analog of 4, 3 beta-hydroxy-7 alpha-methyl-5 alpha-cholestan-15-one (16), and (25R)-3 beta,26-dihydroxy-5 alpha-cholestan-15-one. Full 1H and 13C-NMR data of high precision with complete signal assignments are given for all new compounds. Definitive 1H-NMR stereochemical assignments of the C-24 protons were established for most sterols with a C8H17 side chain based on analysis of the downfield H-24 resonance in a 750-MHz spectrum of 16. Detailed electron-impact mass spectral data are presented together with a summary of major fragmentation patterns for 15-hydroxy- and 15-ketosteroids with and without a delta 8(14) bond.
Anticholesteremic Agents↗
Solvent-controlled diastereoselective synthesis of cyclopentane derivatives by a [3 + 2] cyclization reaction of alpha,beta-disubstituted (alkenyl)(methoxy)carbene complexes with methyl ketone lithium enolates.
Reaction of alpha,beta-unsaturated methoxycarbene complexes 1 and 11 with methyl ketone lithium enolates 2 leads to the corresponding five-membered carbocyclic compounds 4 or diast-4 and 12. The influence of the solvent and/or cosolvent (PMDTA), which turned out to be crucial to direct the reaction to 4 or diast-4, is studied, and a tentative mechanism according to these facts is proposed. In addition, the reaction of carbene complex 1a with alkynyl methyl ketone lithium enolates can be directed to the formal [3 + 2] or [4 + 1] cyclization products by a slight variation of the reaction conditions. Finally, consecutive three-component coupling reactions with carbene complex 1a, lithium enolates 2, and aldehydes 18 to give, in a diastereoselective way, hydroxy carbonyl compounds 19 and tricyclic polyethers 20 are presented.
Aldehydes↗
Structure determination of lithium chloroacetate, lithium bromoacetate and lithium iodoacetate by powder diffraction.
Most halogenoacetates of alkali salts readily undergo a thermally induced polymerization reaction to poly-(hydroxyacetic acid) in the solid state. The lithium salts represent a remarkable exception. The crystal structures of lithium chloroacetate, lithium bromoacetate and lithium iodoacetate were determined ab initio from synchrotron powder diffraction data. The three compounds are isostructural and differ considerably from the structures of sodium chloroacetate and silver chloroacetate, two compounds that undergo polymerization. Most likely, the strong polarizing effect of the small lithium cation is responsible for the unfavorable crystal structure in which each lithium cation is coordinated to four O atoms from four different halogenoacetate molecules. Lithium chloroacetate: a = 9.3882 (9), b = 4.8452 (4), c = 9.0119 (7) Å, beta = 94.330 (5) degrees; lithium bromoacetate: a = 9.7165 (11), b = 4.8610 (6), c = 9.0228 (11) Å, beta = 93.946 (5) degrees; lithium iodoacetate: a = 10.1812 (10), b = 4.8922 (8), c = 9.0468 (10) Å, beta = 93.251 (5) degrees, all crystallizing in space group P2(1)/c with Z = 4.
Journal Article↗
3-Chloropropyl and 4-chlorobutyl phenyl ethers as sources of 1, 3-dilithiopropane and 1,4-dilithiobutane: sequential reaction with carbonyl compounds
The reaction of 3-chloropropyl and 4-chlorobutyl phenyl ethers (1) with lithium powder and a catalytic amount of DTBB (5% molar) in THF at -78 degrees C followed by successive treatment with a carbonyl compound [R(1)R(2)CO = Bu(t)CHO, Me(2)CO, (CH(2))(5)CO, (-)-menthone] at -78 to 20 degrees C and, after 1.5 h at this temperature, with a second one [R(3)R(4)CO = Bu(t)CHO, PhCHO, Me(2)CO, MeCOPr(n), (CH(2))(5)CO, (-)-menthone] at -78 degrees C leads, after hydrolysis with water, to the corresponding 1,5- and 1, 6-diols (2). Because of the competition of two different reductive cleavages, 1,4- and 1,5-diols 3 were also obtained as side-reaction products.
Journal Article↗
Synthesis and antitumor activity of 10-alkyl-10-deazaminopterins. A convenient synthesis of 10-deazaminopterin.
Requirements for large-scale synthesis of the potent antitumor drug 10-deazaminopterin have led to development of a facile synthesis of this compound and its 10-alkyl analogues. The lithium diisopropyl amide generated dianions of appropriate p-alkylbenzoic acids were alkylated with 3-methoxyallyl chloride. The resulting 4-(p-carboxyphenyl)-1-methoxy-1-butenes were brominated at pH 7-8 to afford the 2-bromo-4-(p-carboxyphenyl)butyraldehydes. Condensation with 2,4,5,6-tetraminopyrimidine and subsequent in situ oxidation of the resulting dihydropteridines yielded crystalline 10-alkyl-10-deaza-4-amino-4-deoxypteroic acids. The pteroic acids were coupled with diethyl glutamate via the mixed anhydride method, followed by saponification at room temperature, to give the target 10-deazaminopterins. The 10-alkyl compounds were approximately equipotent to 10-deazaminopterin as growth inhibitors of folate-dependent bacteria. Their abilities to inhibit Lactobacillus casei and L1210 derived dihydrofolate reductases were also similar. Transport properties in vitro were suggestive of an improved therapeutic index for the 10-alkyl analogues. Against L1210 in mice, the percent increase in life span at the LD10 dosage was +151% (methotrexate), +178% (10-deazaminopterin), +235% (10-methyl analogue), and +211% (10-ethyl analogue). 10,10-Dimethyl-10-deazaminopterin was less effective at an equimolar dosage, but the ILS at the maximum dose tested (72 mg/kg) was +135%. It was far less toxic than the other analogues possibly because of enhanced clearance.
Aminopterin↗
Thermoluminescent characteristics of LiKYF5:Pr3+ and KYF4:Tm3 crystals for applications in neutron and gamma dosimetry.
Thermoluminescent (TL) properties of two concentration series lithium potassium yttrium fluoride doped with praseodymium (LiKYF5:Pr3+) and potassium yttrium fluoride doped with thulium (KYF4:Tm3+) have been investigated after gamma and neutron irradiation. The main purpose of this research is to see whether these materials are suitable for gamma and/or neutron dosimetry purposes. It has been found that the compounds of both series are sensitive to 60Co gamma radiation. A maximal TL sensitivity is found for LiKY0.99Pr0.01F5 and KY0.99Tm0.01F4. However, for this doping level the intensity of the TL glow peak is about 7 times less than that for LiF:Mg,Ti (TLD-700). The TL sensitivity to thermal neutrons is relatively higher than that to 60Co photons. No TL sensitivity to fast neutrons was observed.
Crystallization↗
Soluble lanthanide salts (LnCl3.2LiCl) for the improved addition of organomagnesium reagents to carbonyl compounds.
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Indicators and Reagents↗
A search for a strong physisorption site for H2 in Li-doped porous carbons.
The mechanism of hydrogen absorption between two coronene molecules has been studied by first principle calculations. Examination of different sites for H(2) molecule confirmed the classical picture of physisorption. We have also considered molecular hydrogen adsorption in a charged carbon structure achieved by doping with lithium at a density corresponding to the intercalate compound LiC(6). We have performed different types of calculations [Hartree-Fock and density functional theory (DFT)] for various atomic basis sets using CRYSTAL98, GAUSSIAN98, and DMOL3 codes. B3LYP-DFT (B3LYP-three-parameter functional of Backe, Lee, Yang and Parr) energy minimization calculations unravel that there is a stable adsorption site for molecular hydrogen in Li-doped sp(2) carbon structure. These calculations also give an insight into the atomic configurations of interlayer species (H(2) and Li) as the interlayer spacing increases. It can be shown that large changes occur in the positions and electronic properties of interlayer species. Hydrogen molecule does not show any tendency for dissociation and adopts a position in the interlayer void that is deeply related to that of lithium ions. We have evidenced a rather large charge transfer from lithium and capping hydrogen species on neighboring slab carbon atoms that induce the stabilization of molecular hydrogen. We have also found that rotating one carbon layer with respect to the other one (at constant interlayer distance) does not change the adsorption energy to a large extent. The best adsorption site is about five times deeper than the physisorption site found in the undoped case and occurs at an interlayer separation of 5.5+/-0.5 A. The corresponding atomic configuration consists in a hydrogen molecule standing (nearly) perpendicular to the plane surface surrounded by the three lithium ions in a configuration close to that of the LiC(6) intercalation compound.
Journal Article↗
[Augmentation strategies for therapy resistant depression - a review].
OBJECTIVE: Various pharmacological strategies have been developed to treat such refractory depression, of which augmentation therapies are one of the most important. This article reviews both benefits and risks of all known augmentation therapies. METHODS: The relevant literature was identified by means of a computerized MEDLINE research on the years 1990 - 2004 and scanning of review articles. RESULTS: The efficacy of lithium augmentation is very well documented by a large number of controlled studies - lithium augmentation can therefore be recommended in depression refractory to antidepressant treatment. T3 augmentation is - in contrast to lithium augmentation - only a second-line strategy. There is an increasing number of augmentation therapies with atypical antipsychotics - its efficacy already supported by some well designed placebo controlled studies. Augmentation strategies with buspirone, modafinil and dopaminergic agents show good results in some case series and open studies, but there is a lack of doubleblind placebo controlled studies till now. Other augmentation therapies with stimulants, reserpine, pindolol, SAME and Yohimbine are very interesting clinical research strategies with rather little impact on clinical practice at the moment. CONCLUSIONS: The distinct knowledge of available augmentation strategies may help to increase response - as well as remission rates in therapy resistant depression.
Antidepressive Agents↗
Reaction of beta-ethoxyvinyl lithiums generated from phenyltellanyl- and ethyltellanylacetaldehyde diethyl acetals with aldehydes and ketones and successive hydrations.
Reactions of alpha-tellanyl-beta-ethoxyvinyl lithiums of aldehydes and ketones proceeded in good to high yields and the successive treatment with acids gave the alpha-tellanyl alpha,beta-unsaturated aldehydes. alpha-Tellanyl alpha,beta-unsaturated aldehydes easily transformed to more useful compounds.
Aldehydes↗
A new selective cleavage of n,n-dicarbamoyl-protected amines using lithium bromide.
A mild and new procedure for the selective cleavage of an alkoxycarbonyl group (Boc, CBz) in N,N-dicarbamoyl-protected amino compounds is described. The method is based on the use of lithium bromide in acetonitrile and is compatible with a large range of other functionalities present in the substrates. Compared with other reported methodologies, the procedure is particularly useful for the Cbz-selective cleavage in N,N-Ts,Cbz-diprotected amines. A rationalization of the selectivity supported by ab initio calculations is also presented.
Journal Article↗
Selective determination of lithium in biological fluids using flow injection analysis.
The use of flow injection analysis to automated extraction methods for the determination of lithium ion utilizing crown ethers or cryptands is demonstrated. The ion-pair extraction of cryptand 211, lithium, and resazurin exhibits a linear range for lithium ion of 70 ppb to 2.1 ppm. This method could tolerate up to 1000 ppm sodium ion. The chromogenic crown ether, 1-(2-hydroxy-5-nitrobenzyl)-1-aza-4,7,10-trioxacyclododecane, exhibits a linear range for lithium ion of 0.3 to 2 ppm. A sodium ion concentration of 230 ppm can be tolerated. Both extraction systems were used in the automated determination of lithium in blood serum and urine. Both methods agreed well with the known and/or atomic absorption values.
Bridged Bicyclo Compounds↗
X-ray diffraction, spectroscopic and thermal studies on a potential semiorganic NLO material: lithium bis-L-malato borate.
A semiorganic nonlinear optical material, lithium bis-L-malato borate (LBMB) (molecular formula C8H8BLiO10), has been synthesized, and single crystals grown from an aqueous solution, by the method of slow evaporation at 30 degrees C. Crystals of size up to 7 mm x 3 mm x 2 mm were harvested and characterized by powder and single crystal X-ray diffraction and Fourier transform infrared techniques to confirm the identity of the compound formed. The TG-DTA results establish the good thermal stability of the material. The UV-Vis-NIR spectral study reveals that the material has a wide transparency window (230-1500 nm) with a lower cutoff at 230 nm. Kurtz powder test with a Nd:YAG laser indicates the production of SHG output.
Borates↗
Reversible inactivation of dorsal hippocampus by tetrodotoxin impairs blocking of taste aversion selectively during the acquisition but not the retrieval in rats.
The role of the dorsal hippocampus in the different stages of blocking was examined in a taste aversion learning task. Blocking is a learning effect in which one previously conditioned element of a compound makes the conditioning of the added element difficult. An effective blocking procedure with one trial in each stage was tested in unoperated rats. In the first stage, rats drank saccharin and later received lithium chloride by i.p. injection. In the second stage, they were presented with a serial compound saccharin-cider vinegar before lithium injection. In a one-bottle, test a reduced aversion to cider vinegar was observed in this group compared to control groups with no previous saccharin aversion. Bilateral tetrodotoxin (TTX) injection (10 ng/microliters) in the dorsal hippocampus attenuated blocking if this was applied before drinking the compound stimulus during the second stage, but it produced no effect applied either before drinking saccharin in the first stage or before testing. Non-specific retrieval deficit produced by TTX injection applied before testing was ruled out in a control group subjected to a conventional cider vinegar aversion learning which showed complete retrieval of the aversion under TTX. It is concluded that the hippocampal function relevant for blocking takes place during the compound phase.
Acetates↗
Valproate in bipolar disorder: the Canadian perspective.
Lithium is the primary treatment for bipolar disorder. However, a substantial proportion of patients are either lithium-resistant or develop side-effects which limit the effectiveness of treatment. The anticonvulsants, particularly valproate and carbamazepine, are alternatives to lithium in the treatment of bipolar disorder. The data on the efficacy of these compounds are reviewed. Clinical issues relating to their use as an alternative to lithium and potentially as a first-line treatment are discussed. The role of anticonvulsants in the broad range of treatment options available for bipolar patients are evaluated.
Anticonvulsants↗
(Mu-tri-tert-butoxysilanethiolato)bis[(tetrahydrofuran)lithium(I)] and catena-poly[[bis(mu-tri-tert-butoxysilanethiolato)dilithium(I)]-mu-dimethoxyethane]: solvent coordination as the structure-forming factor.
The title compounds, mu-(tri-tert-butoxysilanethiolato-kappa2S:S)-bis[(tetrahydrofuran-kappaO)lithium(I)], [Li2(C12H27O3SSi)2(C4H8O)2], (I), and catena-poly[[bis(mu-tri-tert-butoxysilanethiolato)-1:2kappa(2)S;1kappaS:2kappaS,O-dilithium(I)]-mu-dimethoxyethane-kappa2O:O'], [Li2(C12H27O3SSi)2(C4H10O2)]n, (II), were obtained by the reaction of tri-tert-butoxysilanethiol with metallic lithium. The crude product, when recrystallized from tetrahydrofuran (THF) yields (I), and when recrystallized from 1,2-dimethoxyethane (DME) gives (II). Compound (I) forms centrosymmetric dimers in the solid state with an Li2S2 central core, whereas (II) forms infinitely long chains, in which the centrosymmetric dimeric units are linked together by the bidentate DME ligand (also residing on an inversion centre), thus forming a coordination polymer. The formation of a one-dimensional structure in (II) is a consequence of replacement of a monodentate THF solvent molecule with a bidentate DME molecule.
Journal Article↗
Developmental flavor experience affects utilization of odor, not taste in toxiphobic conditioning.
Feeding experiences were varied in developing rats and the effects upon flavor neophobia and lithium chloride-induced flavor aversions were observed. In Experiment 1, nursing experience of neonate rats was reduced by artificial feeding via intragastric cannula; the rats then were tested with apple juice paired with lithium chloride injection at weaning or maturity. Conditioned aversions were not affected, but neophobia to novel apple juice was attenuated in artificially-reared rats tested at maturity. In Experiment 2, rats received enriched feeding experience after weaning, which consisted of (a) obtaining many complex flavors, a few of which were paired with poisoning, effortlessly in the home cage, or (b) foraging for various foods on an elevated maze. No dramatic effects on neophobia or conditioned taste aversion for saccharin water were apparent. In Experiment 3, rats were given experience after weaning with vanilla-scented water either paired or unpaired with quinine water, and then tested with the odor of almond or that odor compounded with saccharin water for neophobia and lithium-induced aversions. Flavor-experienced rats exhibited more pronounced odor conditioning and more resistance to extinction of the odor aversion after both simple and compound conditioning. In contrast, saccharin taste aversions were relatively unchanged. Apparently, enriched feeding and drinking experience facilitates the utilization of odor more than taste cues.
Animals↗