Synthesis of C-substituted triazoles,isoxazoles, and pyrazoles by 1,3-dipolar cycloaddition to acetylenic sugars

Addition of phenyl azide to 3,5-di-O-acetyl-6,7-dideoxy-1,2-O-isopropylidene-β-l-idio-hept-6-ynofuranose (1) and subsequent saponification gave a 4-substituted 1-phenyl-1,2,3-triazole derivative (3) whose optical rotatory dispersion (o.r.d.) curve was positive. The α-d-gluco analog (5) of 1 similarly gave the 5-epimer (7) of 3; its o.r.d. curve was negative. Both 3 and 7 were degraded to the known 1-phenyl-1,2,3-triazole-4-carboxaldehyde. Similarly, addition of 2,4,6-trimethylbenzonitrile N-oxide to 1 or 5 gave the corresponding, crystalline 3-mesitylisoxazoles as single products; ¹³C-n.m.r. spectroscopy was used to establish the orientation of addition. Related 3-mesitylisoxazoles (11 and 13) were obtained from 1,2:3,4-di-O-isopropylidene-d-glycero-α-d-galacto-oct-7-ynopyranose (10) and its l-glycero 6-epimer (12), respectively; 11 showed the expected, large levorotation, and the 6-epimer 13 was also levorotatory. Benzonitrile (N-phenyl)imine, prepared in situ from 1-(α-chlorobenzylidene)-2-phenylhydrazine and base, did not react with 10 (or its 6-epimer 12), but did react with the 6-keto analog to give a 5-substituted 1,3-diphenyl-1,2-diazole.     

Reaction of derivatives of methyl 2,3-O-benzylidene-6-deoxy-α-L-mannopyranoside with butyllithium: Synthesis of methyl 2, 6-dideoxy-4-O-methyl-α-L-erytho-hexopyranosid-3-ulose

Methyl 2,3-O-benzylidene-6-deoxy-α-L-mannopyranoside (2) reacted with butyllithium to give a mixture of 1,5-anhydro-3-C-butyl-1,2,6-trideoxy-L-ribo-hex-1-enitol (3) and its L-arabino analogue (4), together with methyl 2,3,6-trideoxy-α-L-erythro-hex-2-enopyranoside (5). In contrast, the 4-O-methyl analogue (8) of 2 was converted by butyllithium into methyl 2,6-dideoxy-4-O-methyl-α-L-erythro-hexo-pyranosid-3-ulose (9), which was further characterized as its oxime 10. The 4-O-benzyl analogue of 8, obtained as two separate diastereoisomers (6 and 7) differing in configuration at C-2 of the dioxolane ring, gave a complex mixture of products on treatment with butyllithium.     

Uptake of calcium by microvillous membranes of intestinal epithelial cells

Uptake or “binding” of Ca²⁺ ions by microvillous membranes occurs in the absence or presence of ATP. In its absence uptake is independent of temperature (3–37°C), reduced by the presence of other cations and is dependent upon pH and the number and type of “binding” sites of which there are at least two classes. Under certain conditions uptake of Ca²⁺ is increased by ATP. The degree of stimulation is dependent upon both the concentration of Ca²⁺ and ATP, the time and temperature of incubation and is partly dependent upon the presence of Mg²⁺ ions.     

Studies of insulin release and rat pancreatic islet metabolism with diastereomers of D-glucose

Studies of insulin release with diastereomers and other analogues of D-glucose demonstrated that only sugars which undergo oxidation to CO₂ stimulate insulin release by the pancreatic islet. None of the non-metabolizable diastereomers of glucose stimulated insulin release in the presence of a substimulatory concentration of glucose for fuel. Although 5.5 mM glucose formed 77% as much CO₂ as 16.7 mM mannose and twice that of 16.7 mM fructose, 5.5 mM glucose did not stimulate insulin release whereas 16.7 mM mannose and fructose did stimulate insulin release. These results indicate that the important stimulus for glucose-induced insulin release involves metabolism of glucose, but that the stimulus does not involve solely a fuel function of glucose.     

CD33‐targeting extracellular vesicles deliver antisense oligonucleotides against FLT3‐ITD and miR‐125b for specific treatment of acute myeloid leukaemia

IntroductionAcute Myeloid Leukaemia (AML) is the most common blood cancer in adults. Although 2 out of 3 AML patients go into total remission after chemotherapies and targeted therapies, the disease recurs in 60%–65% of younger adult patients within 3 years after diagnosis with a dramatically decreased survival rate. Therapeutic oligonucleotides are promising treatments under development for AML as they can be designed to silence oncogenes with high specificity and flexibility. However, there are not many well validated approaches for safely and efficiently delivering oligonucleotide drugs. This issue could be resolved by utilizing a new generation of delivery vehicles such as extracellular vesicles (EVs).MethodsIn this study, we harness red blood cell‐derived EVs (RBCEVs) and engineer them via exogenous drug loading and surface functionalization to develop an efficient drug delivery system for AML. Particularly, EVs are designed to target CD33, a common surface marker with elevated expression in AML cells via the conjugation of a CD33‐binding monoclonal antibody onto the EV surface.ResultsThe conjugation of RBCEVs with the CD33‐binding antibody significantly increases the uptake of RBCEVs by CD33‐positive AML cells, but not by CD33‐negative cells. We also load CD33‐targeting RBCEVs with antisense oligonucleotides (ASOs) targeting FLT3‐ITD or miR‐125b, 2 common oncogenes in AML, and demonstrate that the engineered EVs improve leukaemia suppression in in vitro and in vivo models of AML.ConclusionTargeted RBCEVs represent an innovative, efficient, and versatile delivery platform for therapeutic ASOs and can expedite the clinical translation of oligonucleotide drugs for AML treatments by overcoming current obstacles in oligonucleotide delivery.

In this study, we harness red blood cell‐derived EVs (RBCEVs) and engineer them with surface functionalization and exogenous drug loading to develop an efficient drug delivery system for AML. Anti‐CD33 antibody was conjugated to RBCEVs using an enzymatic method combined with the streptavidin‐biotin system. We load the antibody conjugated RBCEVs with ASOs targeting FLT3‐ITD or miR‐125b, 2 common oncogenes in AML, and demonstrate that the treatment with engineered EVs improve leukaemia suppression both in vitro and in vivo.     

Structural and electronic properties of the liver fluke hemoglobin heme cavity by nuclear magnetic resonance: hemin isotope labeling

Reconstitution of liver fluke (Dicrocoelium dendriticum) apo-hemoglobin with hemins selectively deuterated at specific positions has permitted the assignment of several heme resonances in the proton nuclear magnetic resonance spectrum of the Met-aquo and Met-cyano forms of the holoprotein. It was established that in the Met-aquo form the meso protons resonate at positions characteristic of a six-co-ordinated in-plane iron. From this, we deduced that the Met-aquo species retains a bound water molecule at pH values as low as 4.5. The orientation of the proximal histidine imidazole ring with respect to the heme group in the cavity was determined through the identification of the heme methyl signals and the analysis of the hyperfine shift pattern in the Met-cyano hemoglobin proton nuclear magnetic resonance spectrum. Compared to sperm whale myoglobin, the heme appears to be rotated by 180 degrees about the alpha, gamma meso-axis. Protein isomers with the heme group in a reversed orientation were not detected, even shortly after reconstitution. In the Met-cyano form, the resonances most affected by the Bohr transition were shown to arise from the heme propionates.     

Following the recovery of naso-pharyngeal cancer patients by trace elements in hair using statistical pattern recognition methods

This article describes a study where the recovery of nasopharyngeal cancer (NPC) patients was traced by trace elements (TEs) in hair of these patients. These patients whose concentrations of TEs in hair were studied are volunteers who were divided into three groups B, C, and D. Group B was made up of volunteers who had just been diagnosed as having NPC, group C and group D were made up of volunteers who had been diagnosed as having NPC after 3 and 6 mo, respectively, of treatment. For comparison, a control group, namely group A, which was made up of volunteers from healthy persons was added to this study. By implementation of statistic pattern recognition methods, it has been found that the concentrations of TEs in hair can remarkably reflect different recovery phases of NPC patients.