Chemical Etching and TEM Crystalline Quality Assessment of Single Crystalline ZnSe Ingots Grown by I2 Vapor Phase Transport

Crystalline defects were studied in single crystalline ZnSe grown by chemical transport using I2 as gaseous carrier. Transmission electronic microscopy determined an excellent structural order in the micrometric and nanometric range. Larger material areas were studied by chemical etching using different reagents to determine average dislocations density and average adjacent subgrains misorientation. Comparable micrographic results of different reagents are shown. Characterization values of ZnSe commercial substrate grown by High Pressure Bridgman (HPB) have been compared to those that correspond to our grown material wafers. Characterization proved that the semiconductor crystalline quality in our wafers is appropriate for optical devices

Efficient Synthesis of Muramic and Glucuronic Acid Glycodendrimers as Dengue Virus Antagonists

Carbohydrates are involved in many important pathological processes, such as bacterial and viral infections, by means of carbohydrate-protein interactions. Glycoconjugates with multiple carbohydrates are involved in multivalent interactions, thus increasing their binding strengths to proteins. In this work, we report the efficient synthesis of novel muramic and glucuronic acid glycodendrimers as potential Dengue virus antagonists. Aromatic scaffolds functionalized with a terminal ethynyl groups were coupled to muramic and glucuronic acid azides by click chemistry through optimized synthetic strategies to afford the desired glycodendrimers with high yields. Surface Plasmon Resonance studies have demonstrated that the compounds reported bind efficiently to the Dengue virus envelope protein. Molecular modelling studies were carried out to simulate and explain the binding observed. These studies confirm that efficient chemical synthesis of glycodendrimers can be brought about easily offering a versatile strategy to find new active compounds against Dengue virus.Ministerio de Economía y CompetitividadDepto. de Química en Ciencias FarmacéuticasFac. de FarmaciaTRUEpu

Acceptor Specificity of β-N-Acetylhexosaminidase from Talaromyces flavus: A Rational Explanation

Fungal β-N-acetylhexosaminidases, though hydrolytic enzymes in vivo, are useful tools in the preparation of oligosaccharides of biological interest. The β-N-acetylhexosaminidase from Talaromyces flavus is remarkable in terms of its synthetic potential, broad substrate specificity, and tolerance to substrate modifications. It can be heterologously produced in Pichia pastoris in a high yield. The mutation of the Tyr470 residue to histidine greatly enhances its transglycosylation capability. The aim of this work was to identify the structural requirements of this model β-N-acetylhexosaminidase for its transglycosylation acceptors and formulate a structure–activity relationship study. Enzymatic reactions were performed using an activated glycosyl donor, 4-nitrophenyl N-acetyl-β-d-glucosaminide or 4-nitrophenyl N-acetyl-β-d-galactosaminide, and a panel of glycosyl acceptors of varying structural features (N-acetylglucosamine, glucose, N-acetylgalactosamine, galactose, N-acetylmuramic acid, and glucuronic acid). The transglycosylation products were isolated and structurally characterized. The C-2 N-acetamido group in the acceptor molecule was found to be essential for recognition by the enzyme. The presence of the C-2 hydroxyl moiety strongly hindered the normal course of transglycosylation, yielding unique non-reducing disaccharides in a low yield. Moreover, whereas the gluco-configuration at C-4 steered the glycosylation into the β(1-4) position, the galacto-acceptor afforded a β(1-6) glycosidic linkage. The Y470H mutant enzyme was tested with acceptors based on β-glycosides of uronic acid and N-acetylmuramic acid. With the latter acceptor, we were able to isolate and characterize one glycosylation product in a low yield. To our knowledge, this is the first example of enzymatic glycosylation of an N-acetylmuramic acid derivative. In order to explain these findings and predict enzyme behavior, a modeling study was accomplished that correlated with the acquired experimental data

Antitumoral potential of carbamidocyclophanes and carbamidocylindrofridin A isolated from the cyanobacterium Cylindrospermum stagnale BEA 0605B

Three carbamidocyclophanes, A, F and V, and carbamidocylindrofridin A were isolated from the cultured freshwater cyanobacterium Cylindrospermum stagnale, collected in the Canary Islands. The chemical structures of these compounds were elucidated through NMR, HRMS and ECD spectroscopy. The absolute configuration of carbamidocyclophane A was confirmed using X-ray-diffraction. All compounds showed apoptotic capacity against the SK-MEL-1, SK-MEL-28 and SK-MEL-31 tumour cells. Carbamidocylindrofridin A had the highest anti-tumour potential, with an IC50 of 1 ± 0.3 μM in the SK-MEL-1 cell lineThis work was supported by the Fundación de la Universidad Autónoma de Madrid (FUAM

Cybastacines A and B: Antibiotic Sesterterpenes from a <i>Nostoc</i> sp. Cyanobacterium

Cybastacines A (<b>1</b>) and B (<b>2</b>) were discovered as a novel pentacyclic sesterterpenoid–alkaloid skeleton structure, with a guanidinium group. These molecules were isolated from a <i>Nostoc</i> sp. cyanobacterium collected in the Canary Islands. Their structures were elucidated primarily by a combination of spectroscopic analyses and X-ray diffraction. These compounds showed antibiotic activities against several clinically relevant bacterial strains

Cybastacines A and B: Antibiotic Sesterterpenes from a <i>Nostoc</i> sp. Cyanobacterium

Cybastacines A (<b>1</b>) and B (<b>2</b>) were discovered as a novel pentacyclic sesterterpenoid–alkaloid skeleton structure, with a guanidinium group. These molecules were isolated from a <i>Nostoc</i> sp. cyanobacterium collected in the Canary Islands. Their structures were elucidated primarily by a combination of spectroscopic analyses and X-ray diffraction. These compounds showed antibiotic activities against several clinically relevant bacterial strains

Ramucirumab with cisplatin and fluoropyrimidine as first-line therapy in patients with metastatic gastric or junctional adenocarcinoma (RAINFALL): a double-blind, randomised, placebo-controlled, phase 3 trial

BACKGROUND: VEGF and VEGF receptor 2 (VEGFR-2)-mediated signalling and angiogenesis can contribute to the pathogenesis and progression of gastric cancer. We aimed to assess whether the addition of ramucirumab, a VEGFR-2 antagonist monoclonal antibody, to first-line chemotherapy improves outcomes in patients with metastatic gastric or gastro-oesophageal junction adenocarcinoma. METHODS: For this double-blind, randomised, placebo-controlled, phase 3 trial done at 126 centres in 20 countries, we recruited patients aged 18 years or older with metastatic, HER2-negative gastric or gastro-oesophageal junction adenocarcinoma, an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and adequate organ function. Eligible patients were randomly assigned (1:1) with an interactive web response system to receive cisplatin (80 mg/m2, on the first day) plus capecitabine (1000 mg/m2, twice daily for 14 days), every 21 days, and either ramucirumab (8 mg/kg) or placebo on days 1 and 8, every 21 days. 5-Fluorouracil (800 mg/m2 intravenous infusion on days 1-5) was permitted in patients unable to take capecitabine. The primary endpoint was investigator-assessed progression-free survival, analysed by intention to treat in the first 508 patients. We did a sensitivity analysis of the primary endpoint, including a central review of CT scans. Overall survival was a key secondary endpoint. This study is registered with ClinicalTrials.gov, number NCT02314117. FINDINGS: Between Jan 28, 2015, and Sept 16, 2016, 645 patients were randomly assigned to receive ramucirumab plus fluoropyrimidine and cisplatin (n=326) or placebo plus fluoropyrimidine and cisplatin (n=319). Investigator-assessed progression-free survival was significantly longer in the ramucirumab group than the placebo group (hazard ratio [HR] 0·753, 95% CI 0·607-0·935, p=0·0106; median progression-free survival 5·7 months [5·5-6·5] vs 5·4 months [4·5-5·7]). A sensitivity analysis based on central independent review of the radiological images did not corroborate the investigator-assessed difference in progression-free survival (HR 0·961, 95% CI 0·768-1·203, p=0·74). There was no difference in overall survival between groups (0·962, 0·801-1·156, p=0·6757; median overall survival 11·2 months [9·9-11·9] in the ramucirumab group vs 10·7 months [9·5-11·9] in the placebo group). The most common grade 3-4 adverse events were neutropenia (85 [26%] of 323 patients in the ramucirumab group vs 85 [27%] of 315 in the placebo group), anaemia (39 [12%] vs 44 [14%]), and hypertension (32 [10%] vs 5 [2%]). The incidence of any-grade serious adverse events was 160 (50%) of 323 patients in the ramucirumab group and 149 (47%) of 315 patients in the placebo group. The most common serious adverse events were vomiting (14 [4%] in the ramucirumab group vs 21 [7%] in the placebo group) and diarrhoea (11 [3%] vs 19 [6%]). There were seven deaths in each group, either during study treatment or within 30 days of discontinuing study treatment, which were the result of treatment-related adverse events. In the ramucirumab group, these adverse events were acute kidney injury, cardiac arrest, gastric haemorrhage, peritonitis, pneumothorax, septic shock, and sudden death (n=1 of each). In the placebo group, these adverse events were cerebrovascular accident (n=1), multiple organ dysfunction syndrome (n=2), pulmonary embolism (n=2), sepsis (n=1), and small intestine perforation (n=1). INTERPRETATION: Although the primary analysis for progression-free survival was statistically significant, this outcome was not confirmed in a sensitivity analysis of progression-free survival by central independent review, and did not improve overall survival. Therefore, the addition of ramucirumab to cisplatin plus fluoropyrimidine chemotherapy is not recommended as first-line treatment for this patient population. FUNDING: Eli Lilly and Company.status: publishe