Hemostasis of punctured vessels using Doppler-guided high-intensity ultrasound.

The use of Doppler ultrasound was investigated to determine if it would aid in guiding the application of high-intensity focused ultrasound (HIFU) to stop bleeding from punctured vessels. Major vessels (abdominal aorta, illiac, carotid, common femoral and superficial femoral arteries and the jugular vein) were surgically exposed, punctured and treated in anesthetized pigs. Treatment was applied when the Doppler sounds indicated the focus coincided with the bleeding site. In 89 treatment trials, the average time to achieve major hemostasis (a point where bleeding was reduced to a level of only oozing) was 8 s, and for complete hemostasis was 13 s. These times were significantly shorter than those of an identical former study in which only visual guidance was used. In that study, the average times for major and complete hemostasis were 40 and 62 s, respectively. The advantage of Doppler guidance in applying HIFU in treating bleeding vessels was demonstrated.     

Evidence for Trapped Surface Bubbles as the Cause for the Twinkling Artifact in Ultrasound Imaging

The mechanism of the twinkling artifact (TA) that occurs during Doppler ultrasound imaging of kidney stones was investigated. The TA expresses itself in Doppler images as time-varying color. To define the TA quantitatively, beam-forming and Doppler processing were performed on raw per channel radio-frequency data collected when imaging human kidney stones in vitro. Suppression of twinkling by an ensemble of computer-generated replicas of a single radio frequency signal demonstrated that the TA arises from variability among the acoustic signals and not from electronic signal capture or processing. This variability was found to be random, and its suppression by elevated static pressure and return when the pressure was released suggest that the presence of bubbles on the stone surface is the mechanism that gives rise to the TA.     

In vitro sonoluminescence and sonochemistry studies with an electrohydraulic shock-wave lithotripter

Sonoluminescence and sonochemistry from a cavitation field generated by an electrohydraulic shock-wave lithotripter were investigated as functions of spark discharge voltage (13 to 21 kV) and pulse-repetition frequency (PRF) (0.5 to 2.0 Hz). Sonochemical activity, measured with an iodide dosimeter, increased with both voltage and PRF. Sonoluminescence was measured in an acoustically matched light-tight box. The envelope of the light intensity was measured in a temporally gated region extending from the initial arrival of the shock wave (resulting in bubble compression) to the final inertial collapse of the bubble cloud, which follows hundreds of micros after passage of the shock wave. The initial compression resulted in greater sonoluminescence emissions, suggesting that the initial bubble compression due to the leading positive pressure spike from the lithotripter generated higher temperatures than the inertial collapse of the bubble. These unexpected results are consistent with some recent calculations in which the vapor pressure of the liquid limits compressional heating.     

双嘧达莫在汞电极上的电化学行为和吸附性质

在NaOH底液中,双嘧达莫在汞电极上有一不可逆的线性扫描还原峰,E_PC=—1.39V(vs饱和Ag/AgCl)。该峰具有明显的吸附性。当搅拌富集时间较长、双嘧达莫的浓度较小、扫描速度较快时,电极反应几乎完全为吸附态的双嘧达莫所控制。选相交流伏安等实验表明,吸附型体为双嘧达莫中性分子。测得该体系的电子转移数n为4,不可逆吸附的αn_α值为1.72。探讨了双嘧达莫的电极反应机理,建立了用吸附伏安法测定双嘧达莫的最佳条件。     

NF1 optic pathway glioma: analyzing risk factors for visual outcome and indications to treat

BackgroundThe aim of the project was to identify risk factors associated with visual progression and treatment indications in pediatric patients with neurofibromatosis type 1 associated optic pathway glioma (NF1-OPG).MethodsA multidisciplinary expert group consisting of ophthalmologists, pediatric neuro-oncologists, neurofibromatosis specialists, and neuro-radiologists involved in therapy trials assembled a cohort of children with NF1-OPG from 6 European countries with complete clinical, imaging, and visual outcome datasets. Using methods developed during a consensus workshop, visual and imaging data were reviewed by the expert team and analyzed to identify associations between factors at diagnosis with visual and imaging outcomes.ResultsEighty-three patients (37 males, 46 females, mean age 5.1 ± 2.6 y; 1–13.1 y) registered in the European treatment trial SIOP LGG-2004 (recruited 2004–2012) were included. They were either observed or treated (at diagnosis/after follow-up).In multivariable analysis, factors present at diagnosis associated with adverse visual outcomes included: multiple visual signs and symptoms (adjusted odds ratio [adjOR]: 8.33; 95% CI: 1.9–36.45), abnormal visual behavior (adjOR: 4.15; 95% CI: 1.20–14.34), new onset of visual symptoms (adjOR: 4.04; 95% CI: 1.26–12.95), and optic atrophy (adjOR: 3.73; 95% CI: 1.13–12.53). Squint, posterior visual pathway tumor involvement, and bilateral pathway tumor involvement showed borderline significance. Treatment appeared to reduce tumor size but improved vision in only 10/45 treated patients. Children with visual deterioration after primary observation are more likely to improve with treatment than children treated at diagnosis.ConclusionsThe analysis identified the importance of symptomatology, optic atrophy, and history of vision loss as predictive factors for poor visual outcomes in children with NF1-OPG.     

Can mycophenolate mofetil be tapered safely in myasthenia gravis? A retrospective,multicenter analysis

Introduction: Mycophenolate mofetil (MMF) is frequently used to treat myasthenia gravis, but there is little information to guide clinicians on the safety of reducing the dose in well‐controlled patients. Methods: This retrospective chart review at 3 institutions identified 92 patients who had undergone MMF taper after achieving either pharmacologic remission or minimal manifestations status. Statistical analysis was performed to assess differences in patient characteristics between patients who had successfully tapered MMF and those who relapsed. Results: Of 92 patients undergoing a taper, 30 relapsed. The relapses were mild, transient, and usually responded to increased MMF dose. MG crisis did not occur. The mean dose at time of relapse was 888 mg/day. Patients with relapses were tapered more quickly (8.4 vs. 62.4 months). Conclusions: Tapering MMF appears safe after years of disease stability. Reducing the dose at a dose of only 500 mg/day every 12 months is recommended. Muscle Nerve 52 : 211–215, 2015