We investigated a formation channel of triatomic molecular hydrogen ions from ethane dication induced by irradiation of intense laser fields (800 nm, 100 fs, ∼1 × 10(14) W∕cm(2)) by using time of flight mass spectrometry. Hydrogen ion and molecular hydrogen ion (H,D)(n)(+) (n = 1-3) ejected from ethane dications, produced by double ionization of three types of samples, CH(3)CH(3), CD(3)CD(3), and CH(3)CD(3), were measured. All fragments were found to comprise components with a kinetic energy of ∼3.5 eV originating from a two-body Coulomb explosion of ethane dications. Based on the signal intensities and the anisotropy of the ejection direction with respect to the laser polarization direction, the branching ratios, H(+):D(+) = 66:34, H(2)(+):HD(+):D(2)(+) = 63:6:31, and H(3)(+):H(2)D(+):HD(2)(+):D(3)(+) = 26:31:34:9 for the decomposition of C(2)H(3)D(3)(2+), were determined. The ratio of hydrogen molecules, H(2):HD:D(2) = 31:48:21, was also estimated from the signal intensities of the counter ion C(2)(H,D)(4)(2+). The similarity in the extent of H∕D mixture in (H,D)(3)(+) with that of (H,D)(2) suggests that these two dissociation channels have a common precursor with the C(2)H(4)(2+)...H(2) complex structure, as proposed theoretically in the case of H(3)(+) ejection from allene dication [A. M. Mebel and A. D. Bandrauk, J. Chem. Phys. 129, 224311 (2008)]. In contrast, the (H,D)(2)(+) ejection path with a lower extent of H∕D mixture and a large anisotropy is expected to proceed essentially via a different path with a much rapid decomposition rate. For the Coulomb explosion path of C-C bond breaking, the yield ratios of two channels, CH(3)CD(3)(2+)→ CH(3)(+) + CD(3)(+) and CH(2)D(+) + CHD(2)(+), were 81:19 and 92:8 for the perpendicular and parallel directions, respectively. This indicates that the process occurs at a rapid rate, which is comparable to hydrogen migration through the C-C bond, resulting in smaller anisotropy for the latter channel that needs H∕D exchange.
Background and aimsAt Saitama Medical Center, for remission induction in active ulcerative colitis (UC) patients with endoscopic evidence of severe disease, we tend to preferentially use tacrolimus (TAC) over anti-tumor necrosis factor (TNF)-α agents. We conducted this study to evaluate the validity of our therapeutic strategies.Patients and methodsThis retrospective study was conducted in 52 steroid-refractory active UC patients with a Clinical Activity Index (CAI) score of ≥7 who were receiving remission induction therapy with TAC or anti-TNF-α agents. The patients were divided into a TAC treatment group (TAC group, n = 29) and an anti-TNF-α agent treatment group (anti-TNF group, n = 23). The CAI, Ulcerative Colitis Endoscopic Index of Severity (UCEIS) and incidence of events (relapse, hospitalization and surgery) were retrospectively analyzed.ResultsAt treatment initiation, the CAI score was 12.6 in the TAC group and 11.5 in the anti-TNF group (P = 0.09), while the corresponding values of the UCEIS were 6.5 and 5.1, respectively (P = 0.0035). The clinical remission rate at 12 weeks was 55% (65% when only the subgroup that received rapid induction therapy was included in the analysis) in the TAC group and 57% in the anti-TNF group, with no significant difference. The cumulative event-free rates at 1, 6 and 12 months were 65.5%, 39.4%, and 39.4%, respectively, in the TAC group and 95.7%, 77.2% and 71.7%, respectively, in the anti-TNF group (P = 0.0037).ConclusionRapid induction therapy with TAC tended to be selected for active UC patients with endoscopic evidence of severe disease, and the present study supported the validity of this therapeutic approach. However, transition to the remission-maintenance phase was more favorable in the anti-TNF group.
Case seriesPatient: —Final Diagnosis: Ulcerative colitisSymptoms: Diarrhea • hematocheziaMedication: TacrolimusClinical Procedure: —Specialty: Gastroenterology and HepatologyObjective:Unusual setting of medical careBackground:Tacrolimus is reportedly effective for the treatment of refractory ulcerative colitis (UC). At our hospital, there has been an increase in the number of patients, including elderly patients, with refractory UC treated with tacrolimus. Here, we review the data from 5 patients with elderly-onset UC treated with tacrolimus as remission induction therapy.Case Report:The subjects were 5 patients ≥65 years of age with refractory UC who had received oral tacrolimus as remission induction therapy between 2009 and 2014 (3 men and 2 women; median age at onset, 75 years). At the start of the tacrolimus treatment, the median duration of disease was 3 months, and the type of UC was total colitis in 4 cases, and left-sided colitis in 1 case. The drugs used concomitantly at the start of tacrolimus treatment were mesalazine (5 cases) and an immunomodulator drug (1 case). Standard induction therapy (0.05 mg/kg/day) was used in 2 patients and rapid induction therapy (0.1 mg/kg/day) was used in the remaining 3 patients. One week after the start of treatment, the blood trough concentrations of tacrolimus were over the target level of 15 mg/mL in 4 patients. The clinical activity index values on day 0 and day 14 were 10.6±2.1 and 7.6±3.4, respectively. The ulcerative colitis endoscopic index of severity in the remaining 3 patients, after excluding the 2 patients who required colectomy within 14 days after the start of tacrolimus therapy, was 7.3±1.0 before the start of the tacrolimus treatment, improving to 4.5±0.5 on day 14. Subsequently, 1 of these 3 patients was also judged to need surgery due to symptom exacerbation, while complete remission was maintained in the other 2 patients.Conclusions:In elderly-onset refractory UC patients, tacrolimus appears to be effective as remission induction therapy. However, since tacrolimus concentrations in the blood can rise easily in elderly patients, frequent monitoring of the drug concentrations and dosage adjustments are necessary.
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