Towards redox-switchable organocatalysts based on bidentate halogen bond donors.

Redox-active bidentate halogen bond donors based on halopyridinium groups as halogen-bond donating units were synthesized and their structures were elucidated by X-ray diffraction analyses and DFT calculations. Via reversible twofold reduction, these dicationic species can be transformed to neutral compounds which should be much weaker Lewis acids. The corresponding electrochemical data were obtained, and CV as well as UV-vis and NMR techniques were also used to determine binding constants of these halogen bond donors to halides. While all titrations agree on the relative order of binding strengths (with chloride being bound strongest), there are marked deviations in the overall affinity constants which are discussed. In contrast to earlier azo-bridge analogues, the ethylene-linked variants presented herein do not oxidize halides, and thus the novel halogen bond donors could also be used as Lewis acidic organocatalysts in a halide abstraction benchmark reaction, yielding a performance similar to bis(haloimidazolium)-derived catalysts.

Chemical stability of caesium iodide deposits in air/steam atmosphere.

Iodine compounds that may be released in case of severe nuclear accident will have important radiotoxicity if they are disseminated in air. One of the most important iodine species is CsI that is deposited on the surfaces of the reactor coolant system. However, depending on the conditions, CsI can volatilize or react with oxidants to produce I2(g). Theoretical and experimental studies demonstrate that the oxidation of iodide depends on the temperature and in the presence of oxidants in the gas. It is also slightly influenced by the crystallinity of the CsI particles and the nature of the support. In case of a high temperature deposition, the iodine release started at temperature lower than 300 °C. For the CsI vapour and aerosol depositions, the iodine is detected only at temperature above 450 °C and become very important above 550 °C.

Pellagra-like condition is xeroderma pigmentosum/Cockayne syndrome complex and niacin confers clinical benefit.

An extremely rare pellagra-like condition has been described, which was partially responsive to niacin and associated with a multisystem involvement. The condition was proposed to represent a novel autosomal recessive entity but the underlying mutation remained unknown for almost three decades. The objective of this study was to identify the causal mutation in the pellagra-like condition and investigate the mechanism by which niacin confers clinical benefit. Autozygosity mapping and exome sequencing were used to identify the causal mutation, and comet assay on patient fibroblasts before and after niacin treatment to assess its effect on DNA damage. We identified a single disease locus that harbors a novel mutation in ERCC5, thus confirming that the condition is in fact xeroderma pigmentosum/Cockayne syndrome (XP/CS) complex. Importantly, we also show that the previously described dermatological response to niacin is consistent with a dramatic protective effect against ultraviolet-induced DNA damage in patient fibroblasts conferred by niacin treatment. Our findings show the power of exome sequencing in reassigning previously described novel clinical entities, and suggest a mechanism for the dermatological response to niacin in patients with XP/CS complex. This raises interesting possibilities about the potential therapeutic use of niacin in XP.

[Prostate cancer boost using high-dose-rate brachytherapy: impact of the learning curve on the dosimetry]. / Curiethérapie de haut débit de dose après radiothérapie externe d'un cancer de prostate : impact de la courbe d'apprentissage sur la dosimétrie.

PURPOSE: To analyse the influence of the learning curve on dosimetric data for high-dose-rate brachytherapy prostate cancer boost. PATIENTS AND METHODS: From February 2009 to May 2012, after a first course of external beam radiation therapy (46Gy/23 fractions), 124 patients underwent high-dose-rate brachytherapy boost using Plato™ (Nucletron, an Elekta company, Elekta AB, Stockholm, Sweden). The impact of the learning curve on the dosimetric quality of the prostate implant was assessed. The dosimetric data have been analysed: clinical target volume (CTV), D90 (dose to 90 % of CTV), D100, V100 (part on the CTV receiving 100 % of the dose), V150, V200 and DHI (dose non-homogeneity index). The doses delivered to 0.1, 1 and 2 cm(3) of the rectum and urethra were calculated. RESULTS: During the study period (39 months), a significant reduction of V150 (P<0.001), V200 (P<0.001), D0.1rectum (P<0.001), D1rectum (P<0.001), D2rectum (P<0.001), D0.1urethra (P<0.001), and D1urethra (P<0.002) was observed associated with a significant degradation of the D90 (P<0.001) but not significant for the V100 (P=0.29) and the D100 (P=0.3). CONCLUSION: This study confirms that the dosimetric quality of high-dose-rate brachytherapy prostate implant is significantly improved during the learning curve period.

Excessively redundant umbilical skin as a potential early clinical feature of Morquio syndrome and FKBP14-related Ehlers-Danlos syndrome.

Several umbilical abnormalities have been linked to and utilized to aid in the clinical diagnosis of certain syndromes. For instance, umbilical skin redundancy has long been recognized as a core feature of Rieger syndrome although its association with other disorders is unknown. In this article, we report for the first time the occurrence of this distinct clinical sign in association with two other syndromes: Morquio syndrome and FKBP14-related Ehlers-Danlos syndrome (EDS). Our observation is clinically significant because patients with Morquio syndrome are often diagnosed only after they develop typical skeletal manifestations, which reduces the efficacy of available enzyme replacement therapy, so the umbilical sign we report here can facilitate a much earlier diagnosis. In addition, the extreme rarity of FKBP14-related Ehlers-Danlos syndrome (EDS) can greatly delay the diagnosis of this condition unless it is recognized in the differential diagnosis of redundant umbilical skin as we argue in this report.

Mutations in ALDH1A3 cause microphthalmia.

Microphthalmia is an important inborn error of eye development that can be associated with multisystem involvement. Anophthalmia is more severe and rarer. Single mutations in an expanding list of genes are known to cause this spectrum of anomaly. In one branch of a multiplex family with microphthalmia and anophthalmia, autozygome analysis excluded all known microphthalmia genes at the time of doing this study. Exome sequencing and autozygome filtration identified a novel homozygous variant in ALDH1A3. Subsequently, we identified another homozygous variant in 2 of the 10 probands with microphthalmia we specifically screened for mutations in ALDH1A3. Interestingly, the other branch of the original family was found to segregate anophthalmia/syndactyly with a novel homozygous SMOC1 variant. Our data support the very recent and independent identification of ALDH1A3 as a disease gene in microphthalmia. Locus heterogeneity should be considered in consanguineous families even for extremely rare phenotypes.

A large-acceptance beam-deceleration module for retrofitting into ion-source beam lines.

We describe a large-acceptance deceleration module capable of decelerating large-emittance full-intensity ion beams typical of ECR ion sources to very low energies with high efficiency. The deceleration module is designed to permit convenient retrofitting into an existing beam line to replace, e.g., the first Faraday cup after magnetic analysis of the beam extracted from the ion source. For starting energies of 10 keV, and incident ion currents as large as 300 µA, deceleration efficiencies have been measured to be greater than 80% for final energies as low as 70 eV. The decelerated beam intensity can be monitored either by insertion of a beam catcher floating at the final deceleration voltage or from the current to the exit grid itself, with suitable correction applied for the grid transparency factor. The behavior of the deceleration optics was modeled using SIMION, incorporating the effects of intra-beam space charge repulsion. We describe a recent application of this deceleration module to study near-surface He bubble and blister formation of a W target heated to 1250 K and irradiated with a 98 eV He ion beam with a flux of ∼10(16) cm(-2) s(-1).

Osteochondroma of the peroneal tubercle. A report of two cases.

We report two patients with pain on the lateral side of the ankle and foot which was due to stenosing tenosynovitis of the peroneal tendons caused by an osteochondroma of the peroneal tubercle. Surgical treatment produced a good result in both cases. The condition is uncommon, but should be borne in mind as a possible cause of pain in this region.