Ascorbigen A-NMR identification.

The connectivities of all atoms in ascorbigen A, an important metabolite, were determined unambiguously for the first time. The connectivity between carbon atoms was established by 2D INADEQUATE, and one-bond C- C coupling constants were determined for all pairs of directly connected carbon atoms except for two strongly coupled carbon pairs. The C- C coupling in one of the pairs was proved by a modification of standard INADEQUATE; however, the signals from the other pair were too weak to be observed.

Current concept of transurethral resection of bladder cancer: from re-transurethral resection of bladder cancer to en-bloc resection.

Purpose Of Review: Transurethral resection of bladder cancer (TURB) is the critical step in the management of nonmuscle invasive bladder cancer (NMIBC). This review presents new improvements in the strategy and technique of TURB as well as in technological developments used for tumour visualization and removal.

Recent Findings: The goal of TURB is to perform complete resection of NMIBC.

Intermittent Versus Continuous Androgen Deprivation Therapy in Patients with Relapsing or Locally Advanced Prostate Cancer: A Phase 3b Randomised Study (ICELAND).

Background: Intermittent androgen deprivation (IAD) has received increasing attention; however, the current literature is still limited, especially in nonmetastatic prostate cancer (PCa), and the relative efficacy and safety benefits of IAD versus continuous androgen deprivation (CAD) remain unclear.

Objective: To add to the knowledge base regarding efficacy and potential benefits, including reduced side effects and improved quality of life (QoL), of IAD versus CAD in patients with nonmetastatic relapsing or locally advanced PCa.

Design, Setting, And Participants: A 42-mo phase 3b open-label randomised study in 933 patients from 20 European countries.

NMR artifacts caused by decoupling of multiple-spin coherences: improved SLAP experiment.

Contrary to common expectations, multiple-spin coherences containing products of proton and heteronucleus operators (e.g. Hu Cx , u = x, y, z) can produce not only sidebands but also noticeable centerband NMR signals of the heteronucleus during acquisition under 1H broadband decoupling.

In vitro culturing of viable circulating tumor cells of urinary bladder cancer.

Objective: Approximately one third of patients diagnosed with muscle-invasive urinary bladder cancer (UBC) have undetected metastases at the time of treatment of the primary tumor. Currently there are no reliable specific serum markers for monitoring and evaluating risk profiles of urothelial cancers. Several studies suggest that detection of circulating tumor cells (CTCs) may correlate with the disease status and prognosis at baseline and early in the treatment of cancers.

Circulating tumor cells in localized prostate cancer: isolation, cultivation in vitro and relationship to T-stage and Gleason score.

The most promising near-term application of circulating tumor cells (CTCs) monitoring relates to the development of targeted cancer therapies, and the need to tailor such treatments to individual tumor characteristics. A high number of new innovative technologies to improve methods for detecting CTCs, with extraordinarily high sensitivity, have recently been presented. The identification and characterization of CTCs require extremely sensitive and specific methods that are able to isolate CTCs with the possibility of cultivation and downstream analysis of in vitro culture of separated CTCs.

HCSE method for detection of small carbon-carbon couplings and their signs, comparison with SLAP pulse sequence.

Performance of homonuclear coupling sign edited (HCSE) experiment applied to detection of signed carbon-carbon couplings is discussed using a set of already measured samples of nine monosubstituted benzenes. It is shown that coupling sign detection is insensitive to the settings of carbon-carbon polarization transfer delays. The HCSE spectra of ten from the total of 43 measured carbon-carbon couplings were considerably influenced by relaxations and proton-proton strong couplings.

Improved baseline in 29Si NMR spectra of water glasses.

It is shown by experiments that replacing one-pulse sequence by RIDE (ring down elimination) pulse sequence may dramatically improve the baseline of (29)Si NMR spectra and eliminate the signal from the probe.

Small carbon-carbon couplings in monosubstituted benzenes--their signs and magnitudes determined by HCSE method.

Signed values of all intra-ring (2,3,4) J(C,C) couplings in nine monosubstituted benzenes (C6H5-X where X = F, Cl, Br, CH3, OCH3, Si(CH3)3, C≡N, NO, NO2) are experimentally determined as well as nine couplings to substituent carbons. It is confirmed that while all the vicinal intra-ring (3)J(C,C) are positive and all geminal (2)J(C2,C4) are negative, both signs are found for geminal (2)J(C1,C3) couplings. All the determined signs agree with those already predicted by theoretical calculations.

The effect of solvent accessible surface on Hammett-type dependencies of infinite dilution (29)Si and (13)C NMR shifts in ring substituted silylated phenols dissolved in chloroform and acetone.

Infinite dilution (29)Si and (13)C NMR chemical shifts were determined from concentration dependencies of the shifts in dilute chloroform and acetone solutions of para substituted O-silylated phenols, 4-R-C6 H4 -O-SiR'2 R″ (R = Me, MeO, H, F, Cl, NMe2, NH2, and CF3), where the silyl part included groups of different sizes: dimethylsilyl (R' = Me, R″ = H), trimethylsilyl (R' = R″ = Me), tert-butyldimethylsilyl (R' = Me, R″ = CMe3), and tert-butyldiphenylsilyl (R' = C6 H5, R″ = CMe3). Dependencies of silicon and C-1 carbon chemical shifts on Hammett substituent constants are discussed. It is shown that the substituent sensitivity of these chemical shifts is reduced by association with chloroform, the reduction being proportional to the solvent accessible surface of the oxygen atom in the Si-O-C link.

Spectra edited by relative signs of homonuclear couplings of low abundance nuclei.

The proposed homonuclear coupling sign edited (HCSE) experiment can detect signed homonuclear couplings between low abundant nuclei like (13)C, (29)Si and (15)N in linear spin systems, that is, in systems where two nuclei are coupled by the measured coupling, and one of them is coupled by a second coupling to a nucleus of different kind. The third nucleus is usually high abundant hydrogen. Two spectra are measured during the HCSE experiment.

Geminal (2)J((29)Si-O-(29)Si) couplings in oligosiloxanes and their relation to direct (1)J((29) Si-(13)C) couplings.

Absolute values of (79) geminal (2)J((29) Si-O-(29)Si) couplings were measured in an extensive series of (55) unstrained siloxanes dissolved in chloroform-d. Signs of (2)J((29)Si-O-(29)Si) in some (9) silicon hydrides were determined relative to (1)J((29)Si-(1)H) which are known to be negative. It is supposed that positive sign of the (2)J((29)Si-O-(29)Si) coupling found in all studied hydrides is common to all siloxanes.

Precursors and formation of pyrithione and other pyridyl-containing sulfur compounds in drumstick onion, Allium stipitatum.

Two novel, structurally unusual cysteine derivatives were isolated from the bulbs of Allium stipitatum (Allium subg. Melanocrommyum) and shown to be S-(2-pyridyl)cysteine N-oxide and S-(2-pyridyl)glutathione N-oxide. The former compound is the first example of a naturally occurring alliinase substrate that contains an N-oxide functionality instead of the S-oxide group.

Determination of substitution sites in monosubstituted five-membered aromatic heterocycles.

Similar magnitudes of proton-proton couplings across three, four, and five bonds and proton-carbon couplings across two and three bonds combined with difficult to predict substituent effects make the results of an indiscriminate use of routine (COSY, HSQC, HMBC, etc.) techniques for substitution site determination in C-monosubstituted five-membered heteroaromatics suspect. As demonstrated on two examples of natural products, the use of 1,1-ADEQUATE leads to unambiguous substitution site determination lending thus further support to suggested inclusion of 1,1-ADEQUATE data into computer-assisted structure elucidation (CASE) protocols.

Allium discoloration: the precursor and formation of the red pigment in giant onion (Allium giganteum Regel) and some other subgenus Melanocrommyum species.

The precursor of the orange-red pigment formed upon wounding the bulbs of Allium giganteum (Allium subg. Melanocrommyum) was isolated and shown to be S-(2-pyrrolyl)cysteine S-oxide. In addition, two other pyrrolylsulfinyl derivatives were found in an extract from the bulbs, namely, 3-(2-pyrrolylsulfinyl)lactic acid and S-(3-pyrrolyl)cysteine S-oxide.

2D correlation spectra edited by the sign of relative coupling constant.

Modifications (CSEc and CSEh) of recently published SQSQc and SQSQh pulse sequences are proposed and tested on detection of small (∼2 Hz) signed silicon-carbon coupling constants. The new sequences increase signal intensity by simplifying the spectra. The signals are about four times stronger than in SQSQc or SQSQh spectra, achieving the sensitivity of E.

SQSQh: (1)H-detected SQ-SQ experiment for determination of signed silicon-carbon coupling constants.

A new variant of SQ-SQ pulse sequence (SQSQh) for relative sign determination and detection of small silicon-carbon couplings over more than one bond is presented. In the SQSQh sequence, proton detection replaces carbon detection used in the original SQ-SQ pulse sequence (SQSQc). The theoretical gain in sensitivity was experimentally tested on two samples (trimethylsiloxyethane, 1, and 1,2,4-tris(trimethylsiloxy)benzene, 2), the experimentally found gain provided by the SQSQh over the SQSQc method varied between 6 and 8.

Applications of direct analysis in real time-mass spectrometry (DART-MS) in Allium chemistry. (Z)-butanethial S-oxide and 1-butenyl thiosulfinates and their S-(E)-1-butenylcysteine S-oxide precursor from Allium siculum.

Lachrymatory (Z)-butanethial S-oxide along with several 1-butenyl thiosulfinates was detected by DART mass spectrometry upon cutting Allium siculum , a popular ornamental Allium species used in some cultures as a spice. (Z)-Butanethial S-oxide isolated from the plant was shown to be identical to a synthetic sample. Its likely precursor, (R(S),R(C),E)-S-(1-butenyl)cysteine S-oxide (homoisoalliin), was isolated from homogenates of A.

Hydroxamic acids as a novel family of serine racemase inhibitors: mechanistic analysis reveals different modes of interaction with the pyridoxal-5'-phosphate cofactor.

Mammalian serine racemase (SR) is a pyridoxal-5'-phosphate (PLP) dependent enzyme responsible for the biosynthesis of the neurotransmitter D-serine, which activates N-methyl-D-aspartate (NMDA) receptors in the CNS. Aberrant regulation of NMDA receptor signaling has been implicated in a variety of neuropathologies, and inhibitors of SR would therefore be a worthwhile tool for further investigation or treatment of such conditions. Here, we identify a series of small aliphatic hydroxamic acids (HAs) that act as potent SR inhibitors.

SQ-SQ experiment for determination of relative signs of small nJ(29Si,13C) couplings in a wide variety of silicon compounds.

A modification of double quantum-zero quantum (DQ-ZQ) experiment termed single-quantum-single-quantum (SQ-SQ) experiment is proposed for the determination of relative signs and magnitudes of coupling constants. The modification replaces the multiple-quantum evolution period by two synchronously incremented single-quantum periods. Similarly to DQ-ZQ experiment, the sequence requires only two coupling constants that share one nucleus, the one to be measured and a reference one.

Improved pulse sequences for measurement of small long-range couplings between heteronuclei (29Si-13C) at natural abundance.

The gradient pulse sequences for measurement of small long-range couplings between heteronuclei ((29)Si-(13)C) in natural abundance reported to date (INEPT-(Si,C)gCOSY and INEPT-(Si,C,Si)HMQC) suffer from significant signal loss when these nuclei ((29)Si, (13)C) are coupled through one-bond couplings to protons. This negative effect can be completely eliminated by using non-gradient versions (INEPT-(Si,C)COSY) or by switching proton decoupling off during gradient pulses (modified INEPT-(Si,C,Si)gHMQC pulse sequence). The beneficial effects of these two approaches on the quality of the spectra are demonstrated here.

29Si-13C spin-spin couplings over an Si-O-Csp3 link.

(29)Si-(13)C spin-spin couplings over one, two, and three bonds as well as other NMR parameters [delta((29)Si), delta((13)C), delta((1)H), (1)J((13)C-(1)H), and (2)J((29)Si-C-(1)H)] were calculated and measured for a series of trimethylsilylated alcohols of the types Me(3)Si-O-(CH(2))(n)CH(3) and Me(3)Si-O-CH(3-n)R(n)(n = 0-3; R = Me, Ph, or Vi). The signs of the coupling constants determined for selected compounds can likely be extended to all such compounds, as supported by theoretical calculations. Similar to couplings between other pairs of nuclei, the 2-bond and 3-bond (29)Si-O-(13)C couplings are of opposite signs ((2)J > 0 and (3)J < 0), and their relative magnitudes depend on the extent of branching at the alpha-carbon.

Probing the flexibility of internal rotation in silylated phenols with the NMR scalar spin-spin coupling constants.

The rotation of a trimethylsiloxy (TMSO) group in three silylated phenols (with three different ortho substituents -H, -CH3, and -C(CH3)3) was studied with the NMR (n)J(Si,C), n = 2, 3, 4, 5, scalar spin-spin coupling between the (29)Si nucleus of the TMSO group and the (13)C nuclei of the phenyl ring. The internal rotation potential calculated with the B3LYP and MP2 calculation methods including the effect of a solvent environment (gas phase, chloroform, and water) was used for the calculation of the dynamical averages of the scalar coupling constants in the framework of the rigid-bender formalism. Solvent effects, the quality of the rotational potential, and the applicability of the classical molecular dynamic to the problem is discussed.

15N-1H and 15N-13C couplings in 15N-enriched dihydroxamic acids.

(15)N-enriched dihydroxamic acids (HONHCO(CH(2))(n)CONHOH, n = 0, 1, and 2) were prepared and their spectra NMR ((1)H, (13)C, (15)N) recorded in dimethyl sulfoxide (DMSO) solutions with the aim of determining (15)N coupling constants ((15)N-(1)H and (15)N-(13)C). The results supplement chemical shifts published earlier and yield additional support to the structural conclusions derived from other NMR parameters. Notably, no trace of hydroximic structures could be found in the (15)N NMR spectra of these acids.