Combined NMR and X-ray diffraction study of structural aspects, dynamics and charge ordering mechanism in LixVOPO4.2H2O intercalation compounds.

We carried out a detailed investigation of the local ordering and dynamics of the lithium intercalation in paramagnetic LixVOPO4.2H2O (with 0 < x ≤ 1) materials. This question was addressed using a combination of X-ray diffraction, 31P and 7Li MAS NMR experiments. We first studied the structure of the fully ordered end-member of the series, Li1VOPO4.2H2O, revisiting the X-ray single crystal diffraction data on the basis of the information provided by 31P MAS NMR. We then carried out 7Li MAS and exchange NMR experiments and 31P MAS experiments on the polycrystalline powders obtained after partial lithium insertion in VOPO4.2H2O phases. These experiments evidenced an unexpected ageing of the material related with lithium dynamics between the VOPO4 layers and a V4+/V5+ charge ordering mechanism within the layers.

[Erectile dysfunction evaluation after brachytherapy for low risk prostate adenocarcinoma: prospective study of patients with a baseline IIEF5>16]. / Évolution de la fonction érectile après curiethérapie prostatique : étude prospective chez des patients ayant un score IIEF5 initial>16.

PURPOSE: To evaluate erectile function (EF) prospectively from 1 to 2 years post-brachytherapy in patients with a baseline IIEF5 score>16. METHODS: Between 2007 and 2012, 179 patients underwent an exclusive brachytherapy for localised low risk prostate adenocarcinoma. Neo-adjuvant hormotherapy (15.6%) and post-brachytherapy intake phosphodiesterase inhibitors (PDE5i) were not considered as exclusion criteria. EF was evaluated via a scoring questionnaire IIEF5 before the surgical implantation, at month 12 and 24 post-operation. Only patients with an initial IIEF5 score>16 were included. RESULTS: Of the 179 patients, 102 (57%) had a baseline IIEF5>16. At 12 months, 51.1% maintained an IIEF5>16 and 24.5% had a mild to moderate erectile dysfunction (ED), so that a total of 75.6% with IIEF5≥12. About 18% of patients had used PDE5i. At 24 months, 53.2% had an IIEF5>16 and 80.6% had an IIEF5≥12. Severe ED was reported in only 14.5% of the patients. The mean IIEF5 was 16.2 with an average decline of 5 points from the initial stage. All patients who were treated with PDE5i (27%) could have sexual intercourse. EF at baseline was reported as the only predictive factor of ED in multivariate analysis, 70% of patient without ED initially, had an IIEF5>16 at 1 and 2 years. CONCLUSION: Severe ED was quite rare (14%) during the first 2 years post-brachytherapy and more than half of patients maintained an IIEF5>16. The main predictive factor was the erectile function at baseline. LEVEL OF EVIDENCE: 4.

[Tolerance and efficacy of preoperative radiation therapy for elderly patients treated for rectal cancer]. / Tolérance et efficacité de la radiothérapie préopératoire chez les patients âgés atteints d'un cancer du rectum.

PURPOSE: To retrospectively assess the impact of age on tolerance and oncologic outcomes treated by neoadjuvant treatment for patients of 70 years old or above with locally advanced rectal cancer. PATIENTS AND METHODS: Ninety-one consecutive patients were divided into three groups: group 1 from 70 to 75 years (n=31); group 2: 76 to 79 years (n=31) and group 3, patients aged 80 years or above (n=29). Radiation therapy was delivered according two schemes: 25Gy in five fractions (short scheme) or 45 to 50Gy with a classical fractionation (long scheme). Long scheme patients received a concomitant chemotherapy with 5-fluoro-uracile alone or associated with oxaliplatin. RESULTS: The three groups were comparable for performance status, Charlson's score and T staging. Long scheme radiation therapy and chemotherapy were performed in 77.5, 74.5 and 48.3% of patients (P=0.03) and 77.4, 71 and 41.4% (P=0.006) in the groups 1, 2 and 3, respectively. All patients treated with the short scheme irradiation received the treatment without any acute toxicity. In the long scheme group, 65% of patients received the treatment on time and grade 3 or above toxicity was observed in 12% of patients who did not receive oxaliplatin and in 48% of patients who received oxaliplatin. The overall survival rate at 3 and 5 years was 66.9% and 60.8% in the group 1, 90.5% and 75.9% in the group 2 and 80.5% and 73.8% in the group 3 (P=0.15). CONCLUSION: Neoadjuvant treatment is feasible with encouraging survival rates for patients aged 70 years and older. Short scheme radiation therapy seems to be an interesting option in this population.

Impact of learning curve and technical changes on dosimetry in low-dose brachytherapy for prostate cancer.

PURPOSE: To assess the impact of experience and technical changes on peri- and postimplantation (1 month later) dosimetry for permanent prostate brachytherapy (PPB). PATIENTS AND METHODS: From July 2003 to May 2010, 150 prostate cancer patients underwent low-dose, loose-seed I(125) PPB as monotherapy with intraoperative planning. Patients were divided into three groups-P1 (n = 64), P2 (n = 45), P3 (n = 41)-according to the technical changes that occurred during the study period: use of an automatic stepper at the beginning of P2 and a high-frequency ultrasound probe in P3. Peri- and postimplantation dosimetric parameters (on day 30) were reported: D90 (dose received by 90% of prostate volume), V100 and V150 (prostate volume receiving, respectively, 100% and 150% of the prescribed dose), D2 cc and D0.1 cc (doses received by 2 cc and 0.1 cc of the rectum), R100 (rectum volume that received 100% of the prescribed dose), and D10 and D30 (doses received by 10% and 30% of the urethra, only during peri-implantation). RESULTS: We observed a decrease in the number of needles and seeds used over time. The mean peri-implantation D90 was 187.52 Gy without a significant difference between the three periods (p = 0.48). The postimplantation D90, V100, and V150 parameters were, respectively, 168.3 Gy, 91.9%, and 55% with no significant difference between the three periods. The peri-implantation and postimplantation D0.1 cc and R100 significantly decreased over time; on day 30: D0.1 cc P1 = 223.1 Gy vs. D0.1 cc P3 = 190.4 Gy (p = 8.10(-5)) and R100 P1 = 1.06 cc vs. R100 P3 = 0.53 cc (p = 0.0008). CONCLUSION: We observed a learning curve for the implantation parameters, which led to a significant decrease in the rectal doses without having any impact on the prostate dosimetric parameters.

NMR study of the LiMnPO(4)·OH and MPO(4)·H(2)O (M = Mn, V) homeotypic phases and DFT calculations.

Following our previous work on the tavorite-like LiFePO(4)·OH and FePO(4)·H(2)O phases, we report here the magnetic and NMR characterizations of analogous LiMnPO(4)·OH, MnPO(4)·H(2)O and VPO(4)·H(2)O phases together with the DFT calculations of the NMR shifts. The first two compounds exhibit Curie-Weiss type magnetic behavior with Curie constants close to the theoretical ones for HS Mn(3+), while the vanadium compound is very close to a pure Curie-type behavior. (7)Li, (31)P and (1)H MAS NMR spectra are reported for the three compounds, and show strong Fermi-contact shifts for the first two nuclei, while the sign and magnitude of the (1)H shifts are very different for the three phases. DFT calculations (FLAPW in GGA+U approximation) using the WIEN2k code and the experimental susceptibilities are shown to reproduce closely the experimental data. This situation is compared to the case of the homologous and isostructural Fe compounds, which exhibit much more complex magnetic behaviors.

Electric field gradient calculations in paramagnetic compounds using the PAW approach. Application to ²³Na NMR in layered vanadium phosphates.

This article presents ab initio calculations of electric field gradient (EFG) parameters as a tool for the structural characterization of paramagnetic crystalline compounds. Previously reported ²³Na NMR parameters of vanadium + IV containing vanado-phosphate compounds were computed within density functional theory using both cluster and fully periodic approaches. Quadrupolar parameter values measured by ²³Na NMR experiments were reproduced with a level of accuracy comparable to that achievable in diamagnetic compounds and allowed the assignment of observed ²³Na NMR signals. This work demonstrates the utility of the periodic planewave pseudopotential + PAW approach for the calculation of EFG parameters in paramagnetic compounds.

[Erythropoietin and radiotherapy]. / Erythropoïétine et radiothérapie.

Erythropoietin (EPO) is a glycoprotein hormone. This hormone is a growth factor for red blood cells precursors in the bone marrow. The decrease of oxygen partial pressure, a reduced number of erythrocytes caused by bleeding or excessive destruction, or increased tissues oxygen requirements lead to increased secretion of EPO. Its action takes place on bone marrow erythroblastic cells through specific receptors. EPO stimulates the proliferation of red cell precursors stem cells in the bone marrow, thus increasing their production in one to two weeks. The effectiveness of EPO at increasing haemoglobin and improving patients' quality of life has been demonstrated by several studies. However, its use in radiotherapy remains controversial. While tumour hypoxia caused by anaemia is a factor of radio resistance and thus a source of local failure, tumour expression of EPO receptors presents a significant risk for tumour progression and neo-angiogenesis, which would be increased during the administration of EPO. The purpose of this article is to answer the question: is there a place for EPO in combination with radiotherapy in the management of cancer?

Na2[(VO)2(HPO4)2C2O4].2H2O: crystal structure determination from combined powder diffraction and solid-state NMR.

The vanadyl oxalatophosphate Na2[(VO)2(HPO4)2C2O4].2H2O has been synthesized by hydrothermal treatment. Its structure has been determined and refined by combining X-ray powder diffraction and solid-state NMR techniques. It crystallizes with monoclinic symmetry in space group P2(1), a = 6.3534(1) A, b = 17.1614(3) A, c = 6.5632(1) A, beta = 106.597(1) degrees . The structure is related to that of (NH4)2[(VO)2(HPO4)2C2O4].5H2O, which was previously reported. The vanadium phosphate framework consists of infinite [(VO)(HPO4)] chains of corner-sharing vanadium octahedra and hydrogenophosphate tetrahedra. The oxalate groups ensure the connection between the chains to form a 2D structure. The sodium ions and the water molecules are located between the anionic [(VO)2(HPO4)2C2O4]2- layers. The thermal decomposition has been studied in situ by temperature-dependent X-ray diffraction and thermogravimetry. It takes place in three stages, where the first two correspond to water removal and the last to the decomposition of the oxalate group and water elimination, leading to the final product NaVOPO4.

New mercury vanadium phosphate hydrate Hg(4)(-)(x)()O(1-)(y)()((VO)(PO(4))(2).H(2)O with unprecedented tetrahedral oxo-cluster [Hg( approximately )(4)O( approximately )(5)].

The new mercury vanadium phosphate hydrate Hg(4)(-)(x)()O(1)(-)(y)()(VO)(PO(4))(2).H(2)O has been synthesized under hydrothermal conditions. X-ray investigations led to orthorhombic symmetry, space group P2(1)2(1)2(1) (No. 19), a = 6.3632(2) A, b = 12.4155(5) A, c = 14.2292(6) A, Z = 4. The crystal structure was solved and refined from single-crystal diffractometer data to residuals R[F(2) > 2sigmaF(2)] = 0.039, R(w)(F(2)) = 0.055. The VPO framework consists of infinite one-dimensional [VO(PO(4))(2)]( infinity ) chains with corner-connected VO(6) octahedra and PO(4) tetrahedra. The chains run along the [100] direction and are held together by the unprecedented tetrahedral cationic units [Hg(4)(-)(x)()O(1)(-)(y)()](4+). Presence of Hg-Hg bonding contacts is proved from theoretical calculations.

Hydrothermal synthesis, thermal, and magnetic data on new alkaline vanadium phosphate My(VO)9 + x(PO4)4x(HPO4)12 - 4x with M = Cs+ (y = 5.29, x = 1) and M = NH4+, Rb+ (y approximately 5, x approximately 1).

Brownish platelet crystals of My(VO)9 + x(PO4)4x(HPO4)12 - 4x (M = Cs+, NH4+ and Rb+) were prepared hydrothermally. The structure of Cs approximately 5(VO)10(PO4)4(HPO4)8 was solved from single-crystal X-ray diffraction data in the centrosymmetric monoclinic space group C2/c (No. 15) a = 21.1951(8) A, b = 12.2051(4) A, c = 20.6230(8) A, beta = 109.742(2) degrees, Z = 4 (R1(Fo) = 0.054, wR2(Fo2) = 0.123). The structure of Cs approximately 5(VO)10(PO4)4(HPO4)8 is described and compared to that of K2(VO)3(HPO4)4 previously reported by Lii. For the three compounds, thermogravimetric data and susceptibility measurements were investigated and were found to be in agreement with the structural study.