Docetaxel, Cisplatin, and 5-FU Triplet Therapy as Conversion Therapy for Locoregionally Advanced Unresectable Esophageal Squamous Cell Carcinoma.

BACKGROUND: The standard treatment for locoregionally advanced unresectable esophageal squamous cell carcinoma was radical chemoradiotherapy. However, the prognosis was modest. Emerging evidence showed the concept of induction chemotherapy with a goal of conversion surgery. METHODS: We reviewed the long-term, clinical outcomes and safety data of induction chemotherapy using docetaxel-cisplatin-5FU (DCF) and subsequent definitive treatment, either surgery or radical chemoradiotherapy (CRT), in locally advanced unresectable esophageal cancer in Queen Mary Hospital, Hong Kong. A total of 47 patients (median age 62 years, male: 41 (87.2%)) with locoregionally advanced unresectable esophageal cancer received induction DCF. The response rate was 65.9% (complete/partial response: n = 31). After induction DCF, 24 patients (41.4%) had radical surgery and 7 (14.9%) had definitive CRT. RESULTS: The median overall survival (mOS) was significantly longer in patients received subsequent surgery compared with those with definitive CRT (mOS: 40.2 vs. 9.1 months, hazard ratio 3.33, 95% confidence interval 1.22-9.07, p = 0.02) and no definitive treatment (mOS: 40.2 vs. 6.3 months, hazard ratio 8.51, 95% confidence interval 3.7-19.73, p < 0.001). Patients who received surgery, female, and those with supraclavicular lymph node involvement had a better OS. Twenty-one patients (44.7%) developed grade 3/4 adverse events during induction DCF, and two died after chemotherapy because of trachea-esophageal fistula complicated with sepsis. Eleven patients who had surgery had postoperative complications and none had postoperative mortality. CONCLUSIONS: Induction DCF and subsequent conversion surgery offered a chance of cure with long-term survival benefit and manageable toxicities in patients with locoregionally advanced unresectable esophageal cancer.

Combined Angiography and Late Gadolinium Enhancement Acquisition to Improve Assessment of Pulmonary Vein Isolation for Atrial Fibrillation.

PURPOSE: To develop a Shared K-space (SharK) magnetic resonance imaging (MRI) sequence that combines angiographic and late gadolinium enhancement (LGE) acquisitions to improve atrial wall segmentation and scar identification, and to develop a novel visualization method that quantifies scar encirclement of pulmonary veins postablation treatment for atrial fibrillation. MATERIALS AND METHODS: A SharK sequence was developed and used at 3T to image the left atrium in 11 patients postcryoballoon ablation. The effects of sharing k-space between the angiographic and LGE acquisitions on the accuracy of scar were assessed. The left atrial wall was segmented and points about each pulmonary vein (PV) ostia were projected onto a bullseye to quantitatively compare PV encirclement. The parameters used to quantify encirclement were varied to perform a sensitivity analysis. RESULTS: Compared to using a complete set of k-space, total atrial scar differences were significant only when sharing >75% k-space (P = 0.014), and 90% sensitivity and specificity for identifying scar was achieved when sharing 50% k-space. In patients, the right PVs showed more intersubject variance in encirclement compared to the left PVs. A 100° anteroinferior portion of the left PVs was always encircled, while the superior segments of both right PVs was ablated in only 6/11 patients. CONCLUSION: A SharK sequence was developed to combine angiographic and LGE imaging for atrial wall segmentation and scar identification. The PV bullseye quantifies and localizes encirclement about the PVs. The left PVs showed a higher amount of scar encirclement and less variability compared to the right PVs. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:477-486.

Quantification of the focal progression of coronary atherosclerosis through automated co-registration of virtual histology-intravascular ultrasound imaging data.

The goal of this study was to evaluate the accuracy of a novel algorithm that circumferentially co-registers serial virtual histology-intravascular ultrasound (VH-IVUS) data for the focal assessment of coronary atherosclerosis progression. Thirty-three patients with an abnormal non-invasive cardiac stress test or stable angina underwent baseline and follow-up (6 or 12 months) invasive evaluation that included acquisition of VH-IVUS image data. Baseline and follow-up image pairs (n = 4194) were automatically co-registered in the circumferential direction via a multi-variate cross-correlation algorithm. Algorithm stability and accuracy were assessed by comparing results from multiple iterations of the algorithm (iteration 1 vs. iteration 2) and against values determined manually by two expert VH-IVUS readers (algorithm vs. two expert readers). Furthermore, focal plaque progression values were compared between the algorithm and expert readers following co-registration by the independently determined angles. Strong agreement in circumferential co-registration angles were observed across multiple iterations of the algorithm (stability) and between the algorithm and expert readers (accuracy; all concordance correlation coefficients >0.98). Furthermore, circumferential co-registration angles determined by the algorithm were not statistically when compared to values determined by two expert readers (p = 0. 99). Bland-Altman analysis indicated minimal bias when comparing focal VH-IVUS defined plaque progression in corresponding sectors following circumferential co-registration between the algorithm and expert readers. Finally, average differences in changes in total plaque and constituent areas between the algorithm and readers were within the average range of difference between readers (interobserver variability). We present a stable and validated algorithm to automatically circumferentially co-register serial VH-IVUS imaging data for the focal quantification of coronary atherosclerosis progression.

Performance of 3D, navigator echo-gated, contrast-enhanced, magnetic resonance coronary vein imaging in patients undergoing CRT.

PURPOSE: The aims of this study were to evaluate the ability of contrast-enhanced MRI to visualize the coronary veins with validation by the gold standard, X-ray venography, and to determine whether MRI can visualize the coronary vein branch used for left ventricular (LV) lead implantation. MATERIALS AND METHODS: Nineteen (19) patients undergoing cardiac resynchronization therapy (CRT) received a cardiac MRI at 1.5T 1 week before treatment. Coronary vein images were acquired using a 3D, navigator- and ECG-gated, contrast-enhanced, inversion-recovery, fast low-angle shot (FLASH) sequence. X-ray venography was performed during the CRT procedure to image the coronary venous anatomy and the LV lead location. MRI coronary vein images were graded on a 0-3 scale (0 = nonexistent, 1 = poor, 2 = good, 3 = excellent). MRI and X-ray venogram images were also graded using a binary visible/not visible scheme to compare the visibility of the coronary veins. RESULTS: The mean visibility scores for the coronary sinus, the posterior interventricular, the posterior vein of the left ventricle, the left marginal vein, and the anterior interventricular were 3.0 ± 0.2, 2.3 ± 0.7, 1.6 ± 1.1, 1.9 ± 0.8 and 2.4 ± 0.9, respectively. When compared to X-ray venography, MRI was capable of visualizing 90% of veins and all of the veins used for LV lead implantation. The vein used for LV lead implantation had an average vein image quality score of 1.9 on MRI images. CONCLUSIONS: Contrast-enhanced MRI was capable of visualizing 90% of the coronary venous anatomy and was able visualize the vein used for LV lead implantation in all patients.

Postsurgical hemodynamics of the aortic valve bypass operation evaluated with phase contrast magnetic resonance.

PURPOSE: To characterize the postsurgical hemodynamics in aortic valve bypass (AVB) patients, and to determine the relationship between presurgical native aortic valve pressure gradient and postsurgical hemodynamics. MATERIALS AND METHODS: Twenty patients scheduled for AVB surgery underwent presurgical transthoracic Doppler echocardiography to assess the degree of aortic stenosis and postsurgical cardiac magnetic resonance imaging (MRI) to acquire phase contrast magnetic resonance (PCMR) flow values along the ascending and descending aorta, and in the conduit. Net flow values were calculated from the PCMR images and compared to presurgical aortic valve pressure gradient measurements. RESULTS: PCMR showed that: 1) The blood flow split between the aorta and the conduit was 35%:65% of cardiac output and 2) 60% of patients had net retrograde blood flow in the superior thoracic aorta over the cardiac cycle. Patients with presurgical pressure gradient (ΔP) > 45 mmHg had significantly less blood flow out of the native aorta than patients with ΔP < 45 mmHg, and had significantly more retrograde flow in the superior thoracic aorta postsurgery. CONCLUSION: In patients undergoing AVB, presurgical aortic valve pressure gradient is associated with the volume of blood flow out the aorta and the direction of blood flow in the superior thoracic aorta after conduit addition as measured by PCMR.

Using distonic radical ions to probe the chemistry of key combustion intermediates: the case of the benzoxyl radical anion.

The benzoxyl radical is a key intermediate in the combustion of toluene and other aromatic hydrocarbons, yet relatively little experimental work has been performed on this species. Here, a combination of electrospray ionization (ESI), multistage mass spectrometry experiments, and density functional theory (DFT) calculations are used to examine the formation and fragmentation of a benzoxyl (benzyloxyl) distonic radical anion. Excited 4-carboxylatobenzoxyl radical anions were produced via two methods: (1) collision induced dissociation (CID) of the nitrate ester 4-(nitrooxymethyl)benzoate, (-)O2CC6H4CH2ONO2, and (2) reaction of ozone with the 4-carboxylatobenzyl radical anion, (-)O2CC6H4CH2(•). In neither case was the stabilized (-)O2CC6H4CH2O(•) radical anion intermediate detected. Instead, dissociation products at m/z 121 and 149 were observed. These products are attributed to benzaldehyde (O2(-)CC6H4CHO) and benzene ((-)O2CC6H5) products from respective loss of H and HCO radicals in the vibrationally excited benzoxyl intermediate. In no experiments was a product at m/z 120 (i.e., (-)O2CC6H4(•)) detected, corresponding to absence of the commonly assumed phenyl radical + CH2=O channel. The results reported suggest that distonic ions are useful surrogates for reactive intermediates formed in combustion chemistry.

Reaction of aromatic peroxyl radicals with alkynes: a mass spectrometric and computational study using the distonic radical ion approach.

The reaction of the aromatic distonic peroxyl radical cations N-methyl pyridinium-4-peroxyl (PyrOO(.+)) and 4-(N,N,N-trimethyl ammonium)-phenyl peroxyl (AnOO(.+)), with symmetrical dialkyl alkynes 10a-c was studied in the gas phase by mass spectrometry. PyrOO(.+) and AnOO(.+) were produced through reaction of the respective distonic aryl radical cations Pyr(.+) and An(.+) with oxygen, O(2). For the reaction of Pyr(.+) with O(2) an absolute rate coefficient of k(1)=7.1×10(-12) cm(3) molecule(-1) s(-1) and a collision efficiency of 1.2% was determined at 298 K. The strongly electrophilic PyrOO(.+) reacts with 3-hexyne and 4-octyne with absolute rate coefficients of k(hexyne)=1.5×10(-10) cm(3) molecule(-1) s(-1) and k(octyne)=2.8×10(-10) cm(3) molecule(-1) s(-1), respectively, at 298 K. The reaction of both PyrOO(.+) and AnOO(.+) proceeds by radical addition to the alkyne, whereas propargylic hydrogen abstraction was observed as a very minor pathway only in the reactions involving PyrOO(.+). A major reaction pathway of the vinyl radicals 11 formed upon PyrOO(.+) addition to the alkynes involves γ-fragmentation of the peroxy O-O bond and formation of PyrO(.+). The PyrO(.+) is rapidly trapped by intermolecular hydrogen abstraction, presumably from a propargylic methylene group in the alkyne. The reaction of the less electrophilic AnOO(.+) with alkynes is considerably slower and resulted in formation of AnO(.+) as the only charged product. These findings suggest that electrophilic aromatic peroxyl radicals act as oxygen atom donors, which can be used to generate α-oxo carbenes 13 (or isomeric species) from alkynes in a single step. Besides γ-fragmentation, a number of competing unimolecular dissociative reactions also occur in vinyl radicals 11. The potential energy diagrams of these reactions were explored with density functional theory and ab initio methods, which enabled identification of the chemical structures of the most important products.

Noninvasive multimodal evaluation of bioengineered cartilage constructs combining time-resolved fluorescence and ultrasound imaging.

A multimodal diagnostic system that integrates time-resolved fluorescence spectroscopy, fluorescence lifetime imaging microscopy, and ultrasound backscatter microscopy is evaluated here as a potential tool for assessing changes in engineered tissue composition and microstructure nondestructively and noninvasively. The development of techniques capable of monitoring the quality of engineered tissue, determined by extracellular matrix (ECM) content, before implantation would alleviate the need for destructive assays over multiple time points and advance the widespread development and clinical application of engineered tissues. Using a prototype system combining time-resolved fluorescence spectroscopy, FLIM, and UBM, we measured changes in ECM content occurring during chondrogenic differentiation of equine adipose stem cells on 3D biodegradable matrices. The optical and ultrasound results were validated against those acquired via conventional techniques, including collagen II immunohistochemistry, picrosirius red staining, and measurement of construct stiffness. Current results confirm the ability of this multimodal approach to follow the progression of tissue maturation along the chondrogenic lineage by monitoring ECM production (namely, collagen type II) and by detecting resulting changes in mechanical properties of tissue constructs. Although this study was directed toward monitoring chondrogenic tissue maturation, these data demonstrate the feasibility of this approach for multiple applications toward engineering other tissues, including bone and vascular grafts.

Role of 2-oxo and 2-thioxo modifications on the fragmentation reactions of the histidine radical cation.

The fragmentation reactions of the radical cations, M(·+), of histidine, 2-oxo-histidine and 2-thioxo-histidine were examined using a combination of experiments performed on a linear ion trap and density functional theory (DFT) calculations at the UB3-LYP/6-311++G(d,p) level of theory. Low-energy collision-induced dissociation (CID) on [Cu(II)(terpy)(M)](2+) complexes, formed via electrospray ionisation, produced the radical cations in sufficient yield to examine their unimolecular chemistry via an additional stage of CID. The CID spectrum of the radical cation of histidine is dominated by loss of water with the next most abundant ion arising from the combined loss of H(2)O and CO. In contrast, the CID spectra of the radical cations of 2-oxo-histidine and 2-thioxo-histidine are dominated by the combined loss of CO(2) and NH=CH(2). The observed differences are rationalised via DFT calculations which reveal that the barrier associated with loss of CO(2) from the histidine radical cation is higher than that for loss of H(2)O. In contrast, the introduction of an oxygen or sulfur atom into the side chain of histidine results in a reversal of the order of these barrier heights, thus making CO(2) loss the preferred pathway.

Role of 2-oxo and 2-thioxo modifications on the proton affinity of histidine and fragmentation reactions of protonated histidine.

A combination of electrospray ionisation (ESI), multistage and high-resolution mass spectrometry experiments was used to compare the gas-phase chemistry of the amino acids histidine (1), 2-oxo-histidine (2), and 2-thioxo-histidine (3). Collision-induced dissociation (CID) of all three different proton-bound heterodimers of these amino acids led to the relative gas-phase proton affinity order of: histidine >2-thioxo-histidine >2-oxo-histidine. Density functional theory (DFT) calculations confirm this order, with the lower proton affinities of the oxidised histidine derivatives arising from their ability to adopt the more stable keto/thioketo tautomeric forms. All protonated amino acids predominately fragment via the combined loss of H(2)O and CO to yield a(1) ions. Protonated 2 and 3 also undergo other small molecule losses including NH(3) and the imine HN=CHCO(2)H. The observed differences in the fragmentation pathways are rationalised through DFT calculations, which reveal that while modification of histidine via the introduction of the oxygen atom in 2 or the sulfur atom in 3 does not affect the barriers against the loss of H(2)O+CO, barriers against the losses of NH(3) and HN=CHCO(2)H are lowered relative to protonated histidine.

Isomer differentiation via collision-induced dissociation: the case of protonated alpha-, beta2- and beta3-phenylalanines and their derivatives.

A combination of electrospray ionisation (ESI), multistage and high-resolution mass spectrometry experiments is used to examine the gas-phase fragmentation reactions of the three isomeric phenylalanine derivatives, alpha-phenylalanine, beta(2)-phenylalanine and beta(3)-phenylalanine. Under collision-induced dissociation (CID) conditions, each of the protonated phenylalanine isomers fragmented differently, allowing for differentiation. For example, protonated beta(3)-phenylalanine fragments almost exclusively via the loss of NH(3), only beta(2)-phenylalanine via the loss of H(2)O, while alpha- and beta(2)-phenylalanine fragment mainly via the combined losses of H(2)O + CO. Density functional theory (DFT) calculations were performed to examine the competition between NH(3) loss and the combined losses of H(2)O and CO for each of the protonated phenylalanine isomers. Three potential NH(3) loss pathways were studied: (i) an aryl-assisted neighbouring group; (ii) 1,2 hydride migration; and (iii) neighbouring group participation by the carboxyl group. Finally, we have shown that isomer differentiation is also possible when CID is performed on the protonated methyl ester and methyl amide derivatives of alpha-, beta(2)- and beta(3)-phenylalanines.

Mobile protons versus mobile radicals: gas-phase unimolecular chemistry of radical cations of cysteine-containing peptides.

A combination of electrospray ionization (ESI), multistage, and high-resolution mass spectrometry experiments are used to examine the gas-phase fragmentation reactions of radical cations of cysteine containing di- and tripeptides. Two different chemical methods were used to form initial populations of radical cations in which the radical sites were located at different positions: (1) sulfur-centered cysteinyl radicals via bond homolysis of protonated S-nitrosocysteine containing peptides; and (2) alpha-carbon backbone-centered radicals via Siu's sequence of reactions (J. Am. Chem. Soc.2008, 130, 7862). Comparison of the fragmentation reactions of these regiospecifically generated radicals suggests that hydrogen atom transfer (HAT) between the alpha C-H of adjacent residues and the cysteinyl radical can occur. In addition, using accurate mass measurements, deuterium labeling, and comparison with an authentic sample, a novel loss of part of the N-terminal cysteine residue was shown to give rise to the protonated, truncated N-formyl peptide (an even-electron x(n) ion). DFT calculations were performed on the radical cation [GCG]*(+) to examine: the relative stabilities of isomers with different radical and protonation sites; the barriers associated with radical migration between four possible radical sites, [G*CG](+), [GC*G](+), [GCG*](+), and [GC(S*)G](+); and for dissociation from these sites to yield b(2)-type ions.

Gas-phase fragmentation of long-lived cysteine radical cations formed via NO loss from protonated S-nitrosocysteine.

In this work, we describe two different methods for generating protonated S-nitrosocysteine in the gas phase. The first method involves a gas-phase reaction of protonated cysteine with t-butylnitrite, while the second method uses a solution-based transnitrosylation reaction of cysteine with S-nitrosoglutathione followed by transfer of the resulting S-nitrosocysteine into the gas phase by electrospray ionization mass spectrometry (ESI-MS). Independent of the way it was formed, protonated S-nitrosocysteine readily fragments via bond homolysis to form a long-lived radical cation of cysteine (Cys(*+)), which fragments under collision-induced dissociation (CID) conditions via losses in the following relative abundance order: *COOH CH(2)S >> *CH(2)SH approximately = H(2)S. Deuterium labeling experiments were performed to study the mechanisms leading to these pathways. DFT calculations were also used to probe aspects of the fragmentation of protonated S-nitrosocysteine and the radical cation of cysteine. NO loss is found to be the lowest energy channel for the former ion, while the initially formed distonic Cys(*+) with a sulfur radical site undergoes proton and/or H atom transfer reactions that precede the losses of CH(2)S, *COOH, *CH(2)SH, and H(2)S.

Can alpha- and beta-alanine containing peptides be distinguished based on the CID spectra of their protonated ions?

The fragmentation reactions of isomeric dipeptides containing alpha- and beta-alanine residues (alphaAla-alphaAla, alphaAla-betaAla, betaAla-alphaAla, and betaAla-betaAla) were studied using a combination of low-energy and energy resolved collision induced dissociation (CID). Each dipeptide gave a series of different fragment ions, allowing for differentiation. For example, peptides containing an N-terminal beta-Ala residue yield a diagnostic imine loss, while lactam ions at m/z 72 are unique to peptides containing beta-Ala residues. In addition, MS(3) experiments were performed. Structure-specific fragmentation reactions were observed for y(1) ions, which help identify the C-terminal residue. The MS(3) spectra of the b(2) ions are different suggesting they are unique for each peptide. Density functional theory (DFT) calculations predict that b(2) ions formed via a neighboring group attack by the amide are thermodynamically favored over those formed via neighboring group attack by the N-terminal amine. Finally, to gain further insight into the unique fragmentation chemistry of the peptides containing an N-terminal beta-alanine residue, the fragmentation reactions of protonated beta-Ala-NHMe were examined using a combination of experiment and DFT calculations. The relative transition-state energies involved in the four competing losses (NH(3), H(2)O, CH(3)NH(2), and CH(2)=NH) closely follow the relative abundances of these as determined via CID experiments.

Tuning the gas phase redox properties of copper(II) ternary complexes of terpyridines to control the formation of nucleobase radical cations.

Electrospray ionization (ESI) tandem mass spectrometry (MS/MS) of ternary copper(II) complexes of [Cu(terpyX)(M)]2+ (where terpyX = is a substituted 2,2':6',2''-terpyridine ligand; M = the nucleobases: adenine, guanine, thymine and cytosine) was examined as a means of forming radical cations of nucleobases in the gas phase. The following substituents were examined: 4'-NMe2-2,2':6',6''-terpyridine; 4'-OH-2,2':6',6''-terpyridine; 4'-F-2,2':6',6''-terpyridine; 2,2':6',6''-terpyridine; 4'-Cl-2,2':6',6''-terpyridine; 4'-Br-2,2':6',6''-terpyridine; 4'-CO2H-2,2':6',6''-terpyridine; 4'-NO2-2,2':6',6''-terpyridine and 6,6''-dibromo-2',2:6',2''-terpyridine. Each of the ternary complexes [Cu(terpyX)(M)]2+ was mass selected and subjected to collision induced dissociation (CID) in a quadrupole ion trap. The types of fragmentation reactions observed for these complexes depend on the nature of the substituent on the terpyridine ligand, while the yields of the radical cations of the nucleobases follow the order of their ionization energies (IEs): G (lowest IE) > A > C > T (highest IE). In general, radical cation formation is favoured for electron withdrawing substituents (e.g. NO2) while loss of the neutral nucleobase is favoured for electron donating substituents (e.g. NMe2). Loss of the protonated nucleobase is a major fragmentation pathway for the OH substituted terpyridine system, consistent with its ability to bind to a metal centre as a deprotonated ligand. Crystal structure determinations of (6,6''-dibromo-2',2:6',2''-terpyridine)bis(nitrato)copper(II) and diaqua(4'-oxo-2,2':6',6''-terpyridine)copper(II) nitrate monohydrate were performed and correlated with the ESI results.