Arctic "ozone hole" in a cold volcanic stratosphere

Optical depth records indicate that volcanic aerosols from major eruptions often produce clouds that have greater surface area than typical Arctic polar stratospheric clouds (PSCs). A trajectory cloud-chemistry model is used to study how volcanic aerosols could affect springtime Arctic ozone loss processes, such as chlorine activation and denitrification, in a cold winter within the current range of natural variability. Several studies indicate that severe denitrification can increase Arctic ozone loss by up to 30%. We show large PSC particles that cause denitrification in a nonvolcanic stratosphere cannot efficiently form in a volcanic environment. However, volcanic aerosols, when present at low altitudes, where Arctic PSCs cannot form, can extend the vertical range of chemical ozone loss in the lower stratosphere. Chemical processing on volcanic aerosols over a 10-km altitude range could increase the current levels of springtime column ozone loss by up to 70% independent of denitrification. Climate models predict that the lower stratosphere is cooling as a result of greenhouse gas built-up in the troposphere. The magnitude of column ozone loss calculated here for the 1999--2000 Arctic winter, in an assumed volcanic state, is similar to that projected for a colder future nonvolcanic stratosphere in the 2010 decade.     

Clinical evaluation of a new technique to monitor return electrode skin temperature during radiofrequency ablation

Purpose

Return electrode burns occur occasionally in cardiac radiofrequency ablation and more frequently in tumor radiofrequency ablation. A return electrode incorporating a thermochromic liquid crystal (TLC) layer, which changes color with temperature, has been shown in sheep studies to accurately indicate underlying skin temperature. We aimed to validate the accuracy of TLC-coated return electrodes in indicating skin temperature in the clinical setting of cardiac radiofrequency ablation.

Methods and results

The top layer of a standard return electrode was replaced with TLC. Fluoro-optic thermometer (FOT) probes were laid on the skin side of the return electrode, which was then placed on the left lateral mid-thigh of 18 patients (mean age?=?61?±?12 years, 12 men) undergoing cardiac radiofrequency ablation. Return electrode photographs were taken when FOT temperature exceeded 35 °C. TLC color changes, observed in 11 patients, were converted to temperature and compared with FOT temperature. TLC temperature correlated well with FOT temperature (Pearson’s coefficient?=?0.97?±?0.03). Bland–Altman analysis showed good agreement (mean temperature difference?=??0.04?±?0.08 °C, upper limit of agreement?=?0.11?±?0.005 °C, lower limit of agreement?=??0.19?±?0.005 °C). The maximum FOT temperature recorded was 39.6 °C. There was no thermal injury at the return electrode site on any patients, when assessed immediately after and the day following the procedure.

Conclusion

TLC-coated return electrodes accurately indicate underlying skin temperature in cardiac radiofrequency ablation and may help prevent burns. This technology might be essential in high energy radiofrequency ablation.     

Validation of Prosthetic Mitral Regurgitation Quantification Using Novel Angiographic Platform by Mock Circulation

ObjectivesThis study aimed to validate a dedicated software for quantitative videodensitometric angiographic assessment of mitral regurgitation (QMR).BackgroundQuantitative videodensitometric aortography of aortic regurgitation using the time-density principle is a well-documented technique, but the angiographic assessment of mitral regurgitation (MR) remains at best semi-quantitative and operator dependent.MethodsFourteen sheep underwent surgical mitral valve replacement using 2 different prostheses. Pre-sacrifice left ventriculograms were used to assess MR fraction (MRF) using QMR and MR volume (MRV). In an independent core lab, the CAAS QMR 0.1 was used for QMR analysis. In vitro MRF and MRV were assessed in a mock circulation at a comparable cardiac output to the in vivo one by thermodilution. The correlations and agreements of in vitro and in vivo MRF, MRV, and interobserver reproducibility for QMR analysis were assessed using the averaged cardiac cycles (CCs).ResultsIn vivo derived MRF by QMR strongly correlated with in vitro derived MRF, regardless of the number of the CCs analyzed (best correlation: 3 CCs y = 0.446 + 0.994x; R = 0.784; p =0.002). The mean absolute difference between in vitro derived MRF and in vivo derived MRF from 3 CCs was 0.01 ± 4.2% on Bland-Altman analysis. In vitro MRV and in vivo MRV from 3 CCs were very strongly correlated (y = 0.196 + 1.255x; R = 0.839; p < 0.001). The mean absolute difference between in vitro MRV and in vivo MRV from 3 CCs was –1.4 ± 1.9 ml. There were very strong correlations of in vivo MRF between 2 independent analysts, regardless of the number of the CCs.ConclusionsIn vivo MRF using the novel software is feasible, accurate, and highly reproducible. These promising results have led us to initiate the first human feasibility study comprising patients undergoing percutaneous mitral valve edge-to-edge repair.     

Ovarian cancer

Ovarian cancer accounts for 4% of all cancers in women and is the leading cause of death from gynaecologic malignancies. Because early-stage ovarian cancer is generally asymptomatic, approximately 75% of women present with advanced disease at diagnosis. Survival is highly dependent on stage of disease: 5-year survival in patients with early-stage is 80-90% compared to 25% for patients with advanced-stage disease. For all patients, a comprehensive surgical staging should be performed to obtain the histological confirmation of diagnosis and to evaluate the extent of disease. Patients with early-stage should both be optimally staged and be treated with adjuvant platinum-based chemotherapy if they have a medium or high-risk tumour. For advanced disease the currently recommended management is primary cytoreductive surgery followed by platinum-paclitaxel combination chemotherapy. Appropriate salvage therapy is based on the timing and nature of recurrence and the extent of prior chemotherapy. Surgical resection should be considered in patients with long-term remission, especially in those with isolated recurrences and good performance status. Platinum-based combination represents the standard second-line chemotherapy in patients with platinum-sensitive relapsed ovarian cancer. Salvage chemotherapy in platinum-refractory patients usually results in low response rates and short survival.     

Metabolic fate of phenprocoumon in humans

Samples of urine and feces were collected daily from a normal human volunteer who had received a dose of pseudoracemic phenprocoumon [an equimolar mixture of (R)-[12C]- and (S)-[2-13C]phenprocoumon] containing a tracer dose of 10 microCi of [14C]phenprocoumon and analyzed by TLC, HPLC, and GC-MS. After 25 days, 96% of the radiolabeled material was recovered (62.8% in urine and 33.3% in feces). By isotopic dilution and comparison to the Rf values, retention times, and mass fragmentograms of synthetic standards, the metabolites of the drug were identified as the 4'-, 6-, and 7-hydroxy analogues of phenprocoumon. Virtually all of the recovered radioactivity could be accounted for by the parent drug (approximately 40%) and the three metabolites (approximately 60%). The formation of both 4'-(8.1% of administered dose) and 7- (33.4% of administered dose) hydroxyphenprocoumon was highly stereoselective, giving S/R ratios of 2.86 and 1.69, respectively. The formation of 6- (15.5% of administered dose) hydroxyphenprocoumon showed little stereoselectivity (S/R ratio equal to 0.85). The urinary excretion pattern was also confirmed in four additional healthy male subjects who received a single oral dose of pseudoracemic phenprocoumon and whose urine was analyzed by GC-MS. All the drug-related materials (both hydroxylated metabolites and parent compound) that were excreted into the urine were extensively conjugated.