A General Method to Access Underexplored Ylideneamino Sulfates as Interrupted Beckmann-Type Rearrangement Intermediates

The Beckmann rearrangement of ketoximes to their corresponding amides, using a Brønsted acid-mediated fragmentation and migration sequence, has found wide-spread industrial application. We postulated that the development of a methodology to access ylideneamino sulfates using tributylsulfoammonium betaine (TBSAB) would afford isolable Beckmann-type intermediates and competent partners for subsequent rearrangement cascades. The ylideneamino sulfates generated, isolated as their tributylammonium salts, are sufficiently activated to undergo Beckmann rearrangement without additional reagent activation. The generation of sulfuric acid in situ from the ylideneamino sulfate giving rise to a routine Beckmann rearrangement and additional amide bond cleavage to the corresponding aniline was detrimental to reaction success. The screening of bases revealed inexpensive sodium bicarbonate to be an effective additive to prevent classic Brønsted acid-mediated fragmentation and achieve optimal conversions of up to 99%.

Continuous ablation improves lesion maturation compared with intermittent ablation strategies

BACKGROUND

Interrupted ablation is increasingly proposed as part of high-power short-duration radiofrequency ablation (RFA) strategies and may also result from loss of contact from respiratory patterns or cardiac motion. To study the extent that ablation interruption affects lesions.

METHODS

In ex vivo and in vivo experiments, lesion characteristics and tissue temperatures were compared between continuous (group 1) and interrupted (groups 2 and 3) RFA with equal total ablation duration and contact force. Extended duration ablation lesions were also characterized from 1 to 5 minutes.

RESULTS

In the ex vivo study, continuous RFA (group 1) produced larger total lesion volumes compared with each interrupted ablation lesion group (273.8 ± 36.5 vs 205.1 ± 34.2 vs 174.3 ± 32.3 mm³ , all P < .001). Peak temperatures for group 1 were higher at 3 and 5 mm than groups 2 and 3. In vivo, continuous ablation resulted in larger lesions, greater lesion depths, and higher tissue temperatures. Longer ablation durations created larger lesion volumes and increased lesion depths. However, after 3 minutes of ablation, the rate of lesion volume, and depth formation decreased.

CONCLUSIONS

Continuous RFA delivery resulted in larger and deeper lesions with higher tissue temperatures compared with interrupted ablation. This study may have implications for high-power short duration ablation strategies, motivates strategies to reduce variations in ablation delivery, and provides an upper limit for ablation duration beyond which power delivery has diminishing returns.

Comparing Suicide Risk Factors Among Individuals with a History of Aborted, Interrupted, and Actual Suicide Attempts

Recent standardized nomenclature has suggested distinctions among aborted, interrupted, and actual suicide attempts. This study examined differences in self-reported symptoms among individuals with a history of aborted, interrupted, and actual suicide attempts. 167 young adults with a history of suicidality completed self-report measures of suicide attempt history and current symptoms, a clinical interview assessing past suicidal behavior, and a pain tolerance task. Only 78.8% of participants who initially reported a suicide attempt history were classified as suicide attempters following the clinical interview. Individuals who reported only aborted attempts during the clinical interview reported less severe clinical symptoms than those reporting a history of at least one actual attempt. Individuals with a history of actual suicide attempts may represent a more clinically severe group than those with a history of aborted attempts only.

Continuous versus interrupted use of vaginal probiotics plus vaginal clindamycin cream for bacterial vaginosis: a randomized controlled study

Purpose: To compare between continuous and interrupted use of vaginal probiotic after vaginal clindamycin cream for treatment and prevention of recurrence of bacterial vaginosis.Methods: A double-blinded randomized controlled clinical trial, 273 women were randomly allocated to use clindamycin 2% vaginal cream 5 g at bedtime for 7 days followed after 1 week by continuous probiotics vaginal capsule once daily for 6 weeks (n = 129) or clindamycin 2% vaginal cream 5 g at bedtime for 7 days followed by one probiotic vaginal capsule twice a week for 6 weeks (n = 144). The initial evaluation was at 1 week after cessation of probiotics treatment to estimate the cure rates, the follow-up visits were at 1, 3, 6, and 9 months from the initial visit. The primary outcome of this study was cure rate; the secondary outcomes were the frequency of recurrence, the presence of vaginal discharge, pH > 4.5, positive whiff test and detection of clue cells.Results: At the initial visit there was no significant difference in cure rate between continuous probiotics group and interrupted probiotics group (87.4 versus 82.5%; p = .81). There was no significant difference between the two groups in the recurrence rate at one, three, six and 9 months follow up visits (p = .16, p = .42, p = .59, p = .66). There was no significant difference between both groups regarding vaginal discharge reduction, pH dropping, the presence of positive whiff test and detection of clue cells at one, three, six and 9 months follow up visits. Except at 9-month visits, the differences in vaginal discharge reduction and positive whiff test were statically significant.Conclusions: After initial treatment of bacterial vaginosis with vaginal clindamycin cream, the continuous use of vaginal probiotics is equally effective to short repetitive courses in terms of cure rates and prevention of relapse.

Radial fast interrupted steady-state (FISS) magnetic resonance imaging

PURPOSE

To report a highly interrupted radial variant of balanced steady-state free precession (bSSFP) imaging, termed fast interrupted steady-state (FISS), for decreasing flow artifact as well as fat signal conspicuity with respect to bSSFP, and saturation effects vis-à-vis fast low-angle shot (FLASH) imaging.

METHODS

Numerical simulations, phantom studies, and human studies were conducted to examine the imaging contrast, off-resonance behavior, and flow properties of FISS. Human studies applied FISS for cine cardiac imaging and ungated nonenhanced MR angiography (MRA) of the legs, neck, and brain. Comparisons were made with bSSFP and FLASH imaging.

RESULTS

Simulations revealed that FISS retains the high signal levels of bSSFP for stationary on-resonant spins, while reducing undesirable signal heterogeneity from flowing spins. Phantom studies agreed with the simulations, and showed that FISS reduces fat signal and flow artifact with respect to bSSFP imaging. FISS imaging in human subjects agreed with the simulations and phantom studies, and showed reduced saturation artifact compared with FLASH imaging.

CONCLUSION

FISS imaging reduces flow artifact and fat signal conspicuity with respect to bSSFP imaging, and ameliorates arterial signal saturation observed with FLASH imaging. Potential clinical applications include fat-suppressed cine imaging and ungated nonenhanced MRA. Magn Reson Med 79:2077-2086, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Arterial desaturation due to pulmonary arteriovenous malformations after the Kawashima Operation

Arterial desaturation may occur after the Kawashima procedure and, in the absence of venovenous collaterals is usually due to pulmonary arteriovenous malformations. Stenting of the pulmonary arteries, oxygen therapy, and pulmonary vasodilators such as sildenafil have not been able to resolve the arterial desaturation and the only way to do this has been Fontan completion. The time course of the formation of these malformations after the Kawashima and the progression of cyanosis and its resolution after the Fontan has only been demonstrated in case reports and small case series. We pool the available data to model arterial saturations in patients with pulmonary arteriovenous malformations after the Kawashima procedure.