External Sulfate Attack on Cementitious Binders: Limitations and Effects of Sample Geometry on the Quantification of Expansion Stress.

The hollow cylinder method was used to estimate the expansion stress that can occur in concrete due to the crystallisation pressure caused by the formation of ettringite and/or gypsum during external sulphate attack. Hardened cement paste hollow cylinders prepared with Portland cement were mounted in stress cells and exposed to sodium sulphate solutions with two different concentrations (3.0 g L SO42- and 30.0 g L SO42-). Microstructural analysis and finite element modelling was used to evaluate the experimental observations. The expansion stress calculation was verified for a range of diameter/length ratios (0.43-0.60). Thermodynamically predicted maximum expansion stresses are larger than expansion stresses observed in experiments because the latter are affected by the sample geometry, degree of restraint, pore size distribution and relaxation processes. The results indicate that differences in self-constraint at the concave inner and convex outer surfaces of the hollow cylinder lead to an asymmetric expansion stress when ettringite is formed. This leads to macroscopic longitudinal cracks and ultimately failure. Heavy structural components made of concrete are likely to support larger maximum expansion stresses than observed by the hollow cylinder method due to their self-constraint.

Vemurafenib in Langerhans cell histiocytosis: report of a pediatric patient and review of the literature.

Selective BRAF inhibitors such as vemurafenib have become a treatment option in patients with Langerhans cell Histiocytosis (LCH). To date, only 14 patients receiving vemurafenib for LCH have been reported. Although vemurafenib can stabilize the clinical condition of these patients, it does not seem to cure the patients, and it is unknown, when and how to stop vemurafenib treatment. We present a girl with severe multisystem LCH who responded only to vemurafenib. After 8 months of treatment, vemurafenib was tapered and replaced by prednisone and vinblastine, a strategy which has not been described to date. Despite chemotherapy, early relapse occurred, but remission was achieved by re-institution of vemurafenib. Further investigation needs to address the optimal duration of vemurafenib therapy in LCH and whether and which chemotherapeutic regimen may prevent disease relapse after cessation of vemurafenib.

Elevated upper body position improves pregnancy-related OSA without impairing sleep quality or sleep architecture early after delivery.

BACKGROUND: During pregnancy, upper airway resistance is increased, predisposing vulnerable women to pregnancy-related OSA. Elevation of the upper body increases upper airway cross-sectional area (CSA) and improves severity of OSA in a subgroup of nonpregnant patients (positional-dependent sleep apnea). We tested the hypothesis that elevated position of the upper body improves OSA early after delivery. METHODS: Following institutional review board approval, we conducted a randomized, crossover study on two postpartum units of Massachusetts General Hospital. Women during the first 48 h after delivery were included. Polysomnography was performed in nonelevated and 45° elevated upper body position. Upper airway CSA was measured by acoustic pharyngometry in nonelevated, 45° elevated, and sitting body position. RESULTS: Fifty-five patients were enrolled, and measurements of airway CSA obtained. Thirty patients completed polysomnography in both body positions. Elevation of the upper body significantly reduced apnea-hypopnea index (AHI) from 7.7 ± 2.2/h in nonelevated to 4.5 ± 1.4/h in 45° elevated upper body position (P = .031) during sleep. Moderate to severe OSA (AHI > 15/h) was diagnosed in 20% of postpartum patients and successfully treated by elevated body position in one-half of them. Total sleep time and sleep architecture were not affected by upper body elevation. Change from nonelevated to sitting position increased inspiratory upper airway CSA from 1.35 ± 0.1 cm2 to 1.54 ± 0.1 cm2 during wakefulness. Position-dependent increase in CSA and decrease in AHI were correlated (r = 0.42, P = .022). CONCLUSIONS: Among early postpartum women, 45° upper body elevation increased upper airway CSA and mitigated sleep apnea. Elevated body position might improve respiratory safety in women early after delivery. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01719224; URL: www.clinicaltrials.gov.

Elevated body position early after delivery increased airway size during wakefulness, and decreased apnea hypopnea index in a woman with pregnancy related sleep apnea.

We report a patient with pregnancy related obstructive sleep apnea ([OSA]; apnea hypopnea index [AHI] 18/h) early after delivery, with improvement of AHI by 87% following 45-degree elevation in body position compared with the non-elevated position. Improvement associated with this position may be explained, at least in part, by an increased upper airway diameter (as measured during wakefulness). Sleep apnea in this patient resolved at 9 months postpartum. This observation suggests that 45-degree elevated body position may be an effective treatment of pregnancy related OSA during the postpartum period.