Unclassified Lines Research Articles

Growth requirement for methionine in human melanoma-derived cell lines with different levels of MMACHC expression and methylation

Methionine dependence, the inability to grow in culture when methionine in the medium is replaced by its metabolic precursor homocysteine, occurs in many tumor cell lines. In most affected lines, the cause of methionine dependence is not known. An exception is the melanoma-derived cell line MeWo-LC1, in which hypermethylation of the MMACHC gene is associated with decreased MMACHC expression. Decreased expression results in decreased provision of the methylcobalamin cofactor required for activity of methionine synthase and thus decreased conversion of homocysteine to methionine. Analysis of data in the Cancer Cell Line Encyclopedia Archive demonstrated that MMACHC hypermethylation and decreased MMACHC expression occurred more frequently in melanoma cell lines when compared to other tumor cell lines. We further investigated methionine dependence and aspects of MMACHC function in a panel of six melanoma lines, including both melanoma lines with known methionine dependence status (MeWo, which is methionine independent, and A375, which is methionine dependent). We found that the previously unclassified melanoma lines HMCB, Colo829 and SH-4 were methionine dependent, while SK-Mel-28 was methionine independent. However, despite varying levels of MMACHC methylation and expression, none of the tested lines had decreased methylcobalamin and adenosylcobalamin synthesis as seen in MeWo-LC1, and the functions of both cobalamin-dependent enzymes methionine synthase and methylmalonyl-CoA mutase were intact. Thus, while melanoma lines were characterized by relatively high levels of MMACHC methylation and low expression, the defect in metabolism observed in MeWo-LC1 was unique, and decreased MMACHC expression was not a cause of methionine dependence in the other melanoma lines.

Abstract 1407: A dual functional activity subdues the growth of consensus molecular subtypes 1 and 4 in colorectal cancer xenografts

Abstract Purpose: We have synthesized a bifunctional hybrid molecule BO-2762, which is able to induce DNA damage and inhibit angiogenesis simultaneously [1] as similar to first-line chemotherapy combination (FOLFOX + Bevacizumab). Recently, colorectal cancers (CRC) were classified into four consensus molecular types (CMS) [2], CMS 1 to 4. We carried out a translational study to investigate the anti-CRC activity of BO-2762 to various CMS subtypes. Experimental Design: We performed in vitro and in vivo studies to determine the potency and selectivity of first-line combo like hybrid small molecule BO-2762 on a panel of CRC cell lines, which were classified into CMS-1 (LoVo & DLD-1), CMS-2 (LS1034 & SW116), CMS-3 (HT-29 & LS174T), CMS-4 (SW620 & CACO2) and several unclassified cell lines (HCT-116, RKO, & COLO205). Immunohistochemistry was adopted to determine the DNA damage marker (γH2AX) and blood vessel marker (CD31) in the tumor xenografts treated with BO-2762. Results: BO-2762 alone has bifunctional activity by lodging DNA crosslinking in CRC cells and inhibiting tube formation of HUVEC cells at IC50 of 0.50 to 3 μM range. Angiogenesis inhibition was possibly due to the suppression of VEGFR-2 phosphorylation in HUVEC cells and the depletion of VEGF-A in the conditioned media. As reported in previous studies [3], we did not observe non-subtype specific cytotoxicity in in vitro assay system. Intriguingly, animal models exhibited their selective suppression on xenografts of various CMS-1 subtypes, e.g., remarkable suppression in CMS-1 LoVo cells (85.8%) and CMS-4 SW620 cells (83.0%), moderate in CMS-2 LS1034 cells (75.4%), and poor in CMS-3 HT29 cells (44.8%). BO-2762 was administrated at 20 mg/kg via iv injection. Furthermore, by immunohistochemically staining of γH2AX and CD31, we found that BO-2762 was able to induce DNA damage in xenografts of all CMS subtypes but unable to suppress the angiogenesis in CMS-3 HT29 xenografts. Our preliminary results showed enriched VEGF-A and VEGFR2 in HT29 cells. Conclusion: CMS classification paves a medical platform to investigate the combination of anti-angiogenic and DNA crosslinking agents in the CRC selective treatment. BO-2762, a novel hybrid displaying anti-angiogenesis and induction of DNA damage, is functional similar to FOLFOX + Bevacizumab. CMS subtype-specific inhibition in xenografts was likely evented according to their expression levels of angiogenic signaling. Accordingly, BO-2762 has a great potential for further development as a potent and specific anti-CRC agent at least against CMS-1 and 4 subtypes. However, biomarker identification for selecting right patients warrants our further investigation.

Update of Atomic Data for the First Three Spectra of Actinium.

The present article describes a complete reanalysis of all published data on observed spectral lines and energy levels of the first three spectra of actinium (Ac I-III). In Ac I, three previously determined energy levels have been rejected, 12 new energy levels have been found; for six previously known levels, either the J values or the energies have been revised, and the ionization energy has been redetermined with an improved accuracy. In the line list of Ac I, three previous classifications have been discarded, 16 new ones have been found, and three have been revised. In Ac II, 16 new energy levels have been established, and 36 new identifications have been found for previously observed but unclassified lines. In both Ac I and Ac II, new sets of transition probabilities have been calculated. For all three spectra, complete datasets of critically evaluated energy levels, observed lines, and transition probabilities have been constructed to serve as recommended data on these spectra.

New odd-parity energy levels of the neutral lanthanum atom

The discovery of 22 new energy levels of the La atom, having odd parity, is reported. These levels were derived from an analysis of unclassified spectral lines found either in optogalvanic spectra and/or Fourier transform spectra. The reliability of results obtained from the combination principle of Ritz was verified by hyperfine structure investigations. Further three new odd-parity levels of the first La ion are found. For two already known odd-parity levels substantial changes, concerning total angular momentum and hyperfine structure constants A, must be made.

New Energy Levels of Neutral Lanthanum Derived from an Optogalvanic Spectrum between 5610 and 6110 Å

In a previous paper, we reported on a complete optogalvanic (OG) spectrum of a discharge burning in a La–Ar gas mixture, in the spectral range 5610–6110 Å (17,851 to 16,364 cm−1). Now we are able to communicate further new energy levels, found via searching for laser-induced fluorescence lines when exciting unclassified lines from the OG spectrum. We were able to find 17 new levels, and for two further levels, the line list has extended. With the help of these 19 levels, we could classify 132 spectral lines.

Absorption spectrum of neutral krypton in the near infrared region

High-resolution absorption spectra of atomic krypton in the range of 11870-12700 cm $^{-1}$ were recorded by employing concentration modulation absorption spectroscopy technique with a tunable single-mode cw Ti:Sapphire laser. The krypton atoms were excited to the absorbing energy states by discharge-burning in a mixture of helium and krypton. A total of 120 lines of neutral krypton were observed, among them 33 lines had already been classified in previous studies, 45 lines were newly classified with the known energy levels, and 42 lines cannot be classified. These unclassified lines indicate that up to now unknown energy levels of Kr must exist. Further, an analysis of the unclassified lines to get possible new energy levels with a classification program is reported.

Hyperfine structure studies of the odd-parity electronic levels in the holmium atom. II: New levels

This work is devoted to investigations of unclassified spectral lines in atomic holmium, aiming at identification of new electronic levels and determination of their hyperfine structure. Altogether 113 unclassified lines were investigated with the method of laser induced fluorescence in a hollow cathode discharge lamp. As a result, 35 odd-parity electronic levels with previously unknown energies were identified; for all of them the hyperfine structure constants A and B were also determined. The data reported greatly facilitated the semi-empirical fit of the fine and hyperfine structure of the odd-parity level system, performed in our group.

Identification of new electronic levels in the holmium atom and investigation of their hyperfine structure

In this work the hyperfine structure of some tens of unclassified spectral lines in the holmium atom was investigated with the method of laser induced fluorescence in a hollow cathode discharge lamp. As a result, 21 new electronic odd-parity levels, with previously unknown energies within the range 33000–42000 cm−1, were identified and their hyperfine structure constants A and B were determined. The experimental data obtained will facilitate the semi-empirical fit of the fine and hyperfine structure of the odd-parity level system for the atomic holmium, currently in progress in our group.

Abstract 2826: Differential activity of ATR and WEE1 inhibitors in DLBCL subtypes is linked to replication stress and differences in mode of action

Abstract The checkpoint kinases ATR and WEE1 protect cells from replication stress (RS), a hallmark of cancer that has potential to be exploited for cancer treatment. ATR and WEE1 inhibitors are in early clinical trials. Here we report selective anti-tumour activity of inhibitors to ATR (AZD6738) and WEE1 (AZD1775) in a subset of diffuse large B-cell lymphoma (DLBCL) cell lines. Using the cell-of-origin (COO) gene expression scoring system, we found enhanced sensitivity to AZD6738 in the activated B-cell like (ABC, n=6) and unclassified cell lines (n=6) with a combined median GI50 of 0.372 µM, compared to germinal centre B-cell like (GCB, n=7) cell lines, with median GI50 of 1.554 µM. Grouping the cells into AZD6738 sensitive (GI50 ≤ 0.5 µM) or insensitive (≥ 1 µM), we show that the ABC/unclassified COO score, together with high c-MYC protein or CDKN2A/B deletion identified 7/8 sensitive cell lines and 0/7 insensitive cell lines. Furthermore, markers of RS correlated with cell line sensitivity. Treatment of cells with 0.5 µM AZD6738 increased the quantity of 53BP1 nuclear bodies by 3-6 fold across the sensitive cell lines compared to only 2 fold across the insensitive cell lines. DNA fibre analysis also showed that sensitive cells lines had slower rates of replication fork progression (0.80 - 1.12 kbmin-1) compared to insensitive cell lines (1.22 - 1.41 kbmin-1). Across the same DLBCL cell line panel sensitivity to the WEE1 inhibitor AZD1775 was positively correlated with AZD6738 sensitivity, although at lower concentrations. However, using OCI-LY19 and DB cells to reflect high and low replication stress respectively, we show that AZD6738 and AZD1775 differ mechanistically in the extent of DNA damage and apoptosis induced within cell cycle phases. Treatment with 1 µM AZD1775 induced S-phase arrest and increased γH2AX+ cells in S/G2 from 4% to 20% in both cell lines at 8 h, indicating replication-associated DNA damage. However, earlier onset of cell death was observed in the OCI-LY19 cells, with 30% γH2AX+ cells undergoing apoptosis at 24 h compared to 25% γH2AX+ DB cells at 72 h. In contrast, AZD6738 only caused G1 arrest in OCI-LY19 daughter cells, with 20% apoptosis at 72 h. These findings are reflected in the anti-tumour activity of the inhibitors in xenograft DLBCL models in vivo. Once-daily, oral dosing of 50 mg/kg/day AZD6738 or 120 mg/kg/day AZD1775 in OCI-LY19 xenograft model showed efficacy with mean % tumour growth inhibition (%TGI) at day 8 of 104.1% (n=10) and 114.3% (n=10) respectively. In addition, the combination of AZD1775 (60 mg/kg/day; monotherapy %TGI=88.7, n=10) and AZD6738 (25 mg/kg/day; monotherapy %TGI=89.8%, n=10) dosed using a 5 day on, 9 day off dosing schedule was tolerated in mice and resulted in tumour regressions (combination %TGI=108.4%, n=8). These data suggest potential for both single agent and combination opportunities for ATR and WEE1 inhibitors in the DLBCL ABC subtype. Citation Format: Lucy A. Young, Lenka Oplustil O'Connor, Zena Wilson, Corinne Reimer, Alan Lau, Jiri Bartek, Mark J. O'Connor. Differential activity of ATR and WEE1 inhibitors in DLBCL subtypes is linked to replication stress and differences in mode of action [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2826.

New energy levels of atomic niobium (Nb I) discovered by laser-spectroscopic investigations

We report the discovery of 9 previously unknown energy levels of the atomic niobium, all having even parity. Two levels have energies below 19,500 cm−1 and angular momentum J = 3/2, while the energies of the others are located between 39,700 and 43,420 cm−1. The levels were discovered by laser excitation of several unclassified spectral lines in the wavelength range between 554 nm and 650 nm and detection of laser-induced fluorescence with a monochromator.

Experimental Investigation of the Hyperfine Structure of Neutral Praseodymium Spectral Lines and Discovery of New Energy Levels

Experimental investigations of Pr I spectral lines were performed by means of laser induced fluorescence spectroscopy, using a hollow cathode discharge lamp as source of free atoms. The wavelengths for the laser excitation were found by the help of a highly resolved Fourier transform spectrum. Altogether we excited 236 unclassified lines and analysed their hyperfine structure, which led, together with the measured wavelengths of the observed fluorescence lines, to the discovery of 32 new even parity and 38 odd parity fine structure energy levels. These levels allow to classify more than 670 spectral lines of Pr I. The wave number calibrated Fourier transform spectrum allowed us to determine the energies of most of these newly discovered levels with an uncertainty of 0.015 cm-1. Angular momenta, parity, and magnetic and electric hyperfine interaction constants (A and B) of the new levels were also determined.

Finding of previously unknown energy levels using Fourier-transform and laser spectroscopy

In this paper several possibilities of how to find previously unknown energy levels from high-resolution Fourier-transform or laser-generated spectra are discussed. As examples we use levels of neutral Ta, Pr and La. The following methods are used: analysis of Fourier-transform emission spectra, laser-excitation of unclassified spectral lines, analysis of the hyperfine structure of unclassified lines. The discovery of two new La I energy levels is reported.

New Mn II energy levels from the STIS-HST spectrum of the HgMn star HD 175640

The NIST database lists several Mn II lines that were observed in the laboratory but not classified. They cannot be used in spectrum synthesis because their atomic line data are unknown. These lines are concentrated in the 2380-2700 A interval. We aimed to assign energy levels and log gf values to these lines. Semi-empirical line data for Mn II computed by Kurucz were used to synthesize the ultraviolet spectrum of the slow-rotating, HgMn star HD 175640. The spectrum was compared with the high-resolution spectrum observed with the HST-STIS equipment. A UVES spectrum covering the 3050-10000 A region was also examined. We determined a total of 73 new energy levels, 58 from the STIS spectrum of HD 175640 and another 15 from the UVES spectrum. The new energy levels give rise to numerous new computed lines. We have identified more than 50% of the unclassified lines listed in the NIST database and have changed the assignement of another 24 lines. An abundance analysis of the star HD 175640, based on the comparison of observed and computed ultraviolet spectra in the 1250-3040 A interval, is the by-product of this study on Mn II.

Spectrum and energy levels of quadruply-ionized molybdenum (Mo V)

The spectrum of quadruply-ionized molybdenum Mo V was observed from 200 to 4700 Å with sliding spark discharges on 10.7 m normal- and grazing-incidence spectrographs. The existing analyses of this spectrum (Tauheed et al 1985 Phys. Scr. 31 369; Cabeza et al 1986 Phys. Scr. 34 223) were extended to include the 5s2, 5p2, 5s5d, 5s6s, 4d5f, and 4d5g configurations as well as the missing 3H6 level of 4d4f and about 75 levels of the core-excited configuration 4p54d3. The values of the 4d5d 1S0, 5s5p 1P1, and 4d6p 3P0 levels were revised. There are now about 900 lines classified as transitions between 66 even parity and 191 odd parity energy levels. Of these, about 600 lines and 130 levels are new. From the optimized energy level values, Ritz-type wavelengths were determined for about 380 lines, with uncertainties varying from 0.0003 to 0.002 Å. The observed configurations were theoretically interpreted by means of Hartree–Fock calculations and least-squares fits of the energy parameters to the observed levels. The fitted parameters were used to calculate oscillator strengths for all classified lines. A few unclassified lines and undesignated levels are also given. An improved value for the ionization energy was obtained by combining the observed energy of the 4d5g configuration with an ab initio calculation of its term value. The adopted value is 438 900 ± 150 cm−1 (54.417 ± 0.019 eV).

Experimental verification of isotope shift and hyperfine structure of some even parity levels of neutral Eu

The results of measurements of the hyperfine structure of 31 classified and four unclassified spectral lines in the europium atom, obtained by using the laser induced fluorescence method, are presented. On the basis of experimental results, the values of the hyperfine structure constants and the isotope shifts for seven hitherto unmeasured levels belonging to even configurations (among them for three entirely new levels with unknown energies) were determined and the respective values known from literature for another 19 levels were verified. Since the motivation for undertaking investigations within this work was an inconsistency in the semi-empirical description of the hyperfine structure and the isotope shifts for some even levels in the europium atom, a detailed discussion of this problem is presented.

Hyperfine structure and isotope shift measurements of unclassified lines in Eu II and new determination of the partition function

Results of the measurements of isotope shifts and the hyperfine structure for 31 unclassified spectral lines of Eu II, obtained with the laser-induced fluorescence method, are presented. All experimental results are the first results available for these spectral lines. On the basis of measured hyperfine structure constants, J quantum numbers and fluorescence channels (by comparison to the theoretically predicted values), identification of electronic levels was accomplished. The lower levels of the lines investigated were identified as levels belonging to configuration 4f76s. On the basis of the literature values of isotope shifts for this configuration, isotope shifts for lower and upper levels were determined, and, with the use of a sharing rule, contributions of particular configurations in the spectroscopic description of these levels were evaluated. The number of configurations (cores) necessary for description of the Eu II spectrum and the resulting changes of partition function were estimated. Although, due to the lack of transitions to known electronic levels in Eu II, determination of absolute energies of the levels identified was impossible, probable energy values are presented, which might constitute a starting point for investigations in other spectral regions.

HIGH-RESOLUTION FOURIER TRANSFORM SPECTROSCOPY OF LANTHANUM IN Ar DISCHARGE IN THE NEAR-INFRARED

A high-resolution spectrum of lanthanum has been recorded by a Fourier Transform spectrometer in the wavelength range from 833 nm to 1666 nm (6000 cm{sup –1} to 12,000 cm{sup –1}) using as light source a hollow cathode lamp operated with argon as the discharge carrier gas. In total, 2386 spectral lines were detected in this region, of which 555 lines could be classified as La I transitions and 10 lines as La II transitions. All La II transitions and 534 of these La I transitions were classified for the first time, and 6 of the La II transitions and 433 of the classified La I transitions appear to be new lines, which could not be found in the literature. The corresponding energy level data of classified lines are given. Additionally, 430 lines are assigned as Ar I lines and 394 as Ar II lines, of which 179 and 77, respectively, were classified for the first time. All 77 classified Ar II transitions as well as 159 of the classified Ar I transitions are new lines. Furthermore, the wavenumbers of 997 unclassified spectral lines were determined, 235 of which could be assigned as La lines, because of their hyperfine pattern. Themore » remaining 762 lines may be either unclassified Ar lines or unresolved and unclassified La lines with only one symmetrical peak with an FWHM in the same order of magnitude as the Ar lines. The accuracy of the wavenumber for the classified lines with signal-to-noise-ratio higher than four is better than 0.006 cm{sup –1} which corresponds to an accuracy of 0.0004 nm at 830 nm and 0.0017 nm at 1660 nm, respectively.« less

Investigation of Pr I lines by a simulation of their hyperfine patterns: discovery of new levels

Hyperfine structure (hf) patterns of unclassified spectral lines of the praseodymium atom, as appear in a high-resolution Fourier transform spectrum, have been simulated. In this way, the J-values and hf constants of the levels involved in the transitions were determined. Assuming that so far only one unknown level is participating in the transition, these constants were used to identify the known level. The second unknown level was found by performing subtraction or addition of the wave number of the transition to the wave number of the known level. The existence of the new level was then checked by explaining other unclassified lines with respect to the wave number and the hf pattern. In this way, 19 new levels of the praseodymium atom were discovered and are presented in this paper. In some cases, the accuracy of the hf constants was improved by laser-induced fluorescence spectroscopy.

Unidentified lines in the spectra of two iron overabundant CP stars: are they FeII lines?

The analysis of the high-resolution UVES spectra of the chemically peculiar stars HR6000 and 46 Aql has revealed the presence of an impressive number of unidentified lines, mostly concentrated in the regions 4404-4411 Å and 5100-5300 Å. Almost all of the unidentified lines are the same in both stars, which both have an iron abundance enhancement of the order of +0.7 dex over the solar value. The parameters adopted for HR 6000 and 46 Aql are Teff=12850 K, log g=4.1 and Teff=12750 K, log g=3.8, respectively. We show that some of the unknown lines can be identified as high-excitation (lower EP13eV) FeII and that most of them appear as unclassified lines in laboratory iron spectra.

New levels and hyperfine structure evaluation in neutral praseodymium

Fifty seven new electron levels of odd parity in neutral praseodymium are presented. These have been found on the basis of an analysis of hitherto unclassified spectral lines with the method of laser-induced fluorescence (LIF). For all the levels the hyperfine magnetic dipole interaction constants A have been determined.