Laboratory study of heterogeneous ice nucleation in deposition mode of montmorillonite mineral dust particles aged with ammonia, sulfur dioxide, and ozone at polluted atmospheric concentrations

Heterogeneous ice nucleation in deposition mode of montmorillonite mineral dust aerosol particles exposed to atmospheric trace gases (ammonia, sulfur dioxide, and ozone) was studied at temperatures warmer than −40°C with a continuous flow diffusion chamber. Pure and typical polluted atmospheric concentrations of ammonia, sulfur dioxide, and ozone gases were used to age montmorillonite mineral dust aerosol particles at room temperature and atmospheric pressure in a stainless steel chamber. Ammonia-, sulfur dioxide-, and ozone-exposed montmorillonite mineral dust aerosols act as ice nuclei in heterogeneous deposition freezing at warmer temperatures than required for homogeneous freezing. The ice nucleation efficiency of montmorillonite mineral dust aerosols increased about two times due to exposure to ammonia at a typical atmospheric concentration of about 100 ppt. This is the first experimental evidence for the enhancement of the ice nucleation efficiency of montmorillonite mineral dust aerosols by ammonia gas at typical atmospheric concentrations. Montmorillonite exposure to either pure (100%) or 45 ppm sulfur dioxide or to ozone at 200 ppb shows no clear evidence for changing the ice nucleation efficiency of montmorillonite mineral dust particles. Thus, we conclude that enhancements atmospheric trace gases (e.g., sulfur dioxide and ozone) due to anthropogenic activities have no significant impact on the heterogeneous ice nucleation of montmorillonite mineral dust particles.     

Vaginal misoprostol before copper IUD insertion after previous insertion failure: a double-blind,placebo-controlled,parallel-group,randomised clinical trial

Objective: The aim of the study was to assess whether vaginal administration of misoprostol before copper intrauterine device (IUD) insertion increased the success of the procedure among parous women with previous insertion failure.

Methods: A single-centre, parallel-group, double-blind, placebo-controlled, randomised clinical trial was conducted at Ain Shams University Maternity Hospital, Cairo, Egypt, between October 2015 and August 2016. The study comprised 90 parous women undergoing TCu380A IUD insertion after a failed attempt. A computer-generated list of random numbers was used to assign participants to receive either misoprostol 200?μg or a placebo tablet, applied vaginally 10?h and 4?h prior to the second attempted IUD insertion, without ultrasound guidance. The primary outcome was the success of IUD insertion. Secondary outcomes were to establish the effect on insertion success of cervical dilation, cervical softening and previous mode of delivery.

Results: Forty-two women (93.3%) in the misoprostol group and 24 women (53.3%) in the placebo group had a successful IUD insertion (p?<?.001). Cervical dilation was required in 24 women in the misoprostol group and 44 women in the placebo group. Misoprostol application significantly increased insertion success in women with previous caesarean delivery (p?<?.001) but did not affect insertion success in women with previous vaginal delivery (p?=?.481).

Conclusion: Vaginal misoprostol before IUD insertion in parous women with previous insertion failure increased the rate of successful insertion, particularly in women with previous caesarean delivery.     

The therapeutic potential of vasopressin receptor antagonists in congestive heart failure

Hospitalisation of patients presenting with deteriorating congestive heart failure is occurring with increasing frequency and is associated with significant morbidity and mortality. Diuretic use, the mainstay therapy for congestion, is associated with electrolyte abnormalities and deteriorating renal function. In a recent randomised study, tolvaptan, a novel vasopressin antagonist, in addition to standard therapy including diuretics, increased net fluid loss resulting in decreased body weight more effectively than standard therapy alone in patients hospitalised for heart failure. This desirable effect was achieved without adversely affecting blood pressure, heart rate, electrolyte levels, or renal function. Although tolvaptan did not reduce the rate of deteriorating heart failure after discharge, post hoc analysis suggested that mortality might be reduced in high-risk patients treated with tolvaptan. These results make an important contribution to heart failure research, and offer an insight into the future role of vasopressin antagonism in the treatment of congestive heart failure.     

Reliability of carotid doppler performed in a dedicated stroke prevention clinic

INTRODUCTION: Doppler ultrasound (DUS) is used as a screening tool to assess internal carotid artery (ICA) disease. Recent reports suggest that the DUS may be inaccurate in over 28% of patients. We sought to evaluate the accuracy of DUS, when performed in a dedicated stroke prevention clinic (SPC). METHODS: We retrospectively reviewed the charts of patients who had a DUS performed in our SPC, followed by conventional cerebral angiography. Three groups of patients were defined. Group 1 had DUS measured ICA stenosis of >50%; Group II had a DUS measured ICA stenosis of <50%; Group III had complete ICA occlusion on DUS. RESULTS: Sixty-seven patients (69 arteries) were included in the study. There were 45 patients in Group I and based on the findings of cerebral angiography, carotid endarterectomy was considered inappropriate in only one patient--a misclassification rate of 2.2% (95% CI: 0 - 6.5%). Group II consisted of 19 patients and on cerebral angiography, none of these patients had a stenosis of >50%--a misclassification rate of 0%. Group III consisted of five patients in whom DUS showed complete ICA occlusion. The angiogram confirmed the occlusion in all five patients--a misclassification rate of 0%. Overall, misclassification rate was 1.45% (95% CI: 0 - 4.3%). CONCLUSIONS: Doppler ultrasound when performed in a stroke prevention clinic (SPC), has a high accuracy in measuring ICA stenosis of >50%. Doppler ultrasound is reliable in detecting complete ICA occlusion and finally DUS is a reliable screening tool to rule out clinically significant ICA stenosis.