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 13 C-13 C coupling constants were determined for all pairs of directly connected carbon atoms except for two strongly coupled carbon pairs. The 13 C-13 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. The connectivity within the two strongly coupled C-C pairs was confirmed by a combination of COSY and gHSQC; the latter experiment also identified all C-H bonds. The proton nuclear magnetic resonance (1 H NMR) spectra in dry dimethyl sulfoxide allowed identification and assignment of the signals due to NH and OH protons. The derived structure, 3-((1H-indol-3-yl)methyl)-3,3a,6-trihydroxytetrahydrofuro[3,2-b]furan-2(5H)-one, agrees with the structure suggested for ascorbigen A in 1966. The density functional theory (DFT) calculations showed that among 16 possible stereoisomers, only two complied with the almost zero value of the measured 3 J(H6-H6a). Of the two stereoisomers, 3S,3aS,6S,6aR and 3R,3aR,6R,6aS, the latter was excluded on synthetic grounds. The nuclear Overhauser effect measurements unveiled close proximity between H2' proton of the indole and the H6a proton of the tetrahydrofuro[3,2-b]furan part. Detailed structural interpretation of the measured NMR parameters by means of DFT NMR was hampered by rotational flexibility of the indole and tetrahydrofuro[3,2-b]furan parts and inadequacy of Polarizable Continuum Model (PCM) solvent model.

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. Tumor visualization during procedure can be improved by enhanced optical technologies. Fluorescence-guided photodynamic diagnosis (PDD) and narrow-band imaging (NBI) used during TURB can improve tumour detection and potentially reduce recurrence rate, their influence on progression, however, remains controversial. TURB can be performed using monopolar or bipolar electrocautery without significant differences in results or safety. To overcome limitations of traditional TURB, the technique of en-bloc resection was introduced to improve the quality of tumour removal. In selected cases, an early re-resection (re-TURB) within 2-6 weeks after initial procedure is recommended. SUMMARY: TURB is a fundamental step in diagnosis and treatment of NMIBC. Urologists should be aware of promising innovations including new imaging and surgical techniques and their potential benefits. Hopefully, new technologies and performance of TURB bring improved outcomes, which can alter the indication criteria for re-TURB.

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. INTERVENTION: Following a 6-mo induction with leuprorelin acetate (Eligard) 22.5mg 3-mo depot, patients were randomised to CAD or IAD with leuprorelin for 36 mo. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary end point was time to prostate-specific antigen (PSA) progression while receiving luteinising hormone-releasing hormone agonist, defined as three consecutive increasing PSA values ≥ 4 ng/ml ≥ 2 wk apart. Secondary end points included PSA progression-free survival (PFS), overall survival (OS), testosterone levels, performance status, and QoL. RESULTS AND LIMITATIONS: A total of 933 patients entered the induction phase; 701 were randomised. The median number of injections administered after randomisation was 12 (range: 1-12) for the CAD group and 3 (range: 1-10) for the IAD group. There were no statistically significant or clinically relevant differences between the groups for time to PSA progression, PSA PFS, OS, mean PSA levels over time, or QoL. A similar number of adverse events was observed in each group; the most common were hot flushes and hypertension. Study limitations include the open-label design and absence of formal testosterone recovery assessment. CONCLUSIONS: IAD and CAD demonstrated similar efficacy, tolerability, and QoL in men with nonmetastatic PCa. The principal benefit of IAD compared with CAD is a potential cost reduction with comparable OS rates. There are no apparent QoL benefits. PATIENT SUMMARY: This randomised trial showed that both intermittent and continuous hormone therapy had similar efficacy, tolerability, and quality-of-life profiles in patients with relapsing M0 or locally advanced prostate cancer. Intermittent therapy may be a valid option for selected patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT00378690.

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. Such centerband signals of low abundant heteronuclei can be sources of relatively strong unexpected artifacts in NMR experiments that aim to detect very weak signals from much less-abundant isotopomers, e.g. 13C-13C ones. These findings lead to a new design of Sign Labeled Polarization Transfer (SLAP) pulse sequence (MSS-SLAP) with improved suppression of centerband peaks that are because of singly, e.g. 13C, labeled molecules (parent peaks). The MSS-SLAP experiment and its MSS-BIRD-SLAP variant are compared with a few older SLAP versions.

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. In this study a new way of isolation and in vitro cultivation of CTCs of urinary bladder cancer was introduced. MATERIALS AND METHODS: Peripheral blood (PB) samples from 53 patients who had undergone urological procedure were evaluated using the MetaCell device (MetaCell s.r.o., Ostrava, Czech Republic). The patients enrolled in the study were both oncological patients with UBC and non-oncological patients with inflammation (14 patients). The sensitivity and quantification of CTCs were evaluated. The separated CTCs were cultured in vitro. RESULTS: 39 patients with confirmed UBC were enrolled in the study. CTCs were detected in 25 (64%) patients, and most of these patients had between 6 and 10 cells. The separated CTCs were successfully cultured in vitro. CONCLUSION: CTCs were detected in a higher percentage of patients than in other studies. This paper describes the first successful culturing of human UBC cells. The MetaCell approach used in this study enabled the capture of viable intact virgin CTCs (virgin CTC) suitable for next in vitro culturing, single cell analysis or drug testing.

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. In this original research paper, we demonstrate that it is possible to isolate human CTCs from a patient with prostate cancer, with subsequent cultivation and proliferation in vitro. We show that the use of a filtration device implemented by MetaCell® can fulfil all the requirements mentioned above. Fifty-five patients with localized prostate cancer have so far been enrolled into the study. CTCs were detected in the blood samples of 28 (52%) out of the 55 patients. We report successful isolation of CTCs from patients with prostate cancer, capturing cells with a proliferative capacity in 18 (64.3%) out of the 28 CTC-positive patients. Direct correlation with Gleason score and T stage was not proven. The cells, captured by a size-based filtration approach, remain in a good state, unaffected by any antibodies or lysing solutions. During the filtration process, no interactions occurred between antibodies and antigens on the surface of CTCs. This biological interaction is specific for immunomagnetic methods. The MetaCell device provides the possibility of reaching virgin CTCs suitable for subsequent cultivation or single-cell analysis. This aspect will have an important impact on the future design of clinical trials testing new drugs against targets expressed on metastatic cancer cells. In addition to measurement of CTC counts, future trials with targeted therapies should also include the assessment of the specific therapeutic target on 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. These effects are quantitatively discussed. The results of HCSE and SLAP experiments are compared. It is shown that the two methods may complement each other in detection of signed carbon-carbon 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. Their weighed sum and difference yield two other spectra, one containing peaks coupled only by positive measured couplings and the other having peaks coupled by negative measured couplings. The usual E.COSY-type experiment requires all three couplings in the three spin system (triangular spin system) and not only two couplings as the HCSE experiment. The experiment was successfully tested on known carbon-carbon and silicon-silicon two bond couplings. A set of six simple siloxanes with |(2) J(Si-O-Si)| couplings ranging from 0.5 to 9.0 Hz was measured for the first time, and all the couplings were found to be positive.

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. Theoretical calculations for simple model compounds failed to reproduce this sign and so their predictions of bond length and angle dependences cannot be taken as reliable. Useful empirical correlations were found between the (2)J((29)Si-O-(29)Si) couplings on one side and the total number m of oxygen atoms bonded to the silicon atoms, sum of (29)Si chemical shifts or product of (1)J((29)Si-(13)C) couplings on the other side. The significance of these correlations is briefly discussed.

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. In addition, S-methylcysteine S-oxide (methiin) and S-(methylthiomethyl)cysteine 4-oxide (marasmin) were found in the bulbs. Presented data suggest that the previously reported identification of S-(2-pyridyl)cysteine S-oxide was most likely erroneous. The alliinase-mediated formation of pyridyl-containing compounds following disruption of A. stipitatum bulbs was studied by a combination of HPLC-MS, HPLC-PDA, DART-MS, and NMR techniques. It was found that no pyridyl-containing thiosulfinates are present in homogenized bulbs in detectable quantities. Instead, various pyridine N-oxide derivatives are formed, including N-hydroxypyridine-2(1H)-thione (pyrithione), 2-(methyldithio)pyridine N-oxide, 2-[(methylthio)methyldithio]pyridine N-oxide, di(2-pyridyl) disulfide N-oxide, and di(2-pyridyl) disulfide N,N'-dioxide. This represents the first report of pyrithione formation as a natural product.

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. Contrary to a previous report, the latter compound was shown not to serve as the precursor of the pigment, being in fact only an artifact formed during isolation. The formation of pyrrolyl-containing compounds following disruption of A. giganteum bulbs was studied by a combination of LC-MS, LC-NMR and DART-MS. It was found that S-(2-pyrrolyl)cysteine S-oxide is cleaved by a C-S lyase (alliinase) to yield 2-pyrrolesulfenic acid. Two molecules of the latter compound give rise to highly reactive S-(2-pyrrolyl) 2-pyrrolethiosulfinate which in turn converts into red 2,2'-epidithio-3,3'-dipyrrole (dipyrrolo[2,3-d:2',3'-e]-1,2-dithiin). Several other pyrrolyl-containing compounds were detected in A. giganteum for the first time, including S-methyl 2-pyrrolethiosulfinate, S-(2-pyrrolyl) methanethiosulfinate, di(2-pyrrolyl) disulfide, and S-(2-pyrrolyl) 2-pyrrolethiosulfonate. It can be concluded that the formation of the orange-red pigment in Allium subg. Melanocrommyum species, despite sharing several analogous features, is of a different nature than the pink discoloration of onion (A. cepa).

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.

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.COSY-type experiment. The information about sign and magnitude of the coupling is preserved. CSEc and CSEh spectra for two silicon compounds are presented and compared. The two new sequences allow editing of heteronuclear correlation spectra according to the sign of the selected heteronuclear coupling constants.

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. The method can be applied to linear spin systems, i.e. to systems where the silicon is coupled to the carbon in question and to any hydrogen not necessarily bonded to the carbon.

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. siculum, and a closely related species Allium tripedale , and fully characterized. Through use of LC-MS, a series of related gamma-glutamyl derivatives were tentatively identified in A. siculum and A. tripedale homogenates, including gamma-glutamyl-(E)-S-(1-butenyl)cysteine and its S-oxide, gamma-glutamyl-S-butylcysteine and its S-oxide, and gamma-glutamyl-S-methylcysteine and its S-oxide. Because compounds containing the 1-butenyl group have not been previously identified in genus Allium species, this work extends the range of known Allium sulfur compounds. The general applicability of DART mass spectrometry in identifying naturally occurring, thermally fragile thial S-oxides and thiosulfinates is illustrated with onion, Allium cepa , as well as a plant from a different genus, Petiveria alliacea .

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. However, specificity studies showed that some of these HAs can act as nonspecific inhibitors of PLP-dependent enzymes. We employed NMR, MS, and UV/vis spectroscopic techniques to reveal that the nonspecific effect is likely due to irreversible interaction of the HA moiety with PLP to form aldoxime species. We also characterize L-aspartic acid beta-hydroxamate as a competitive and selective SR inhibitor that could be used as a scaffold for further inhibitor development.