Creating Order in Ultrastable Phosphonate Metal-Organic Frameworks via Isolable Hydrogen-Bonded Intermediates.

The stability presented by trivalent metal-organic frameworks (MOFs) makes them an attractive class of materials. With phosphonate-based ligands, crystallization is a challenge, as there are significantly more binding motifs that can be adopted due to the extra oxygen tether compared to carboxylate counterparts and the self-assembly processes are less reversible. Despite this, we have reported charge-assisted hydrogen-bonded metal-organic frameworks (HMOFs) consisting of [Cr(HO)] and phosphonate ligands, which were crystallographically characterized.

Characterization and assembly of the Pseudomonas aeruginosa aspartate transcarbamoylase-pseudo dihydroorotase complex.

Pseudomonas aeruginosa is a virulent pathogen that has become more threatening with the emergence of multidrug resistance. The aspartate transcarbamoylase (ATCase) of this organism is a dodecamer comprised of six 37 kDa catalytic chains and six 45 kDa chains homologous to dihydroorotase (pDHO). The pDHO chain is inactive but is necessary for ATCase activity.

Pressure-induced activation of latent dihydroorotase from Aquifex aeolicus as revealed by high pressure protein crystallography.

Dihydroorotase (DHOase) is involved in the de novo synthesis of pyrimidine in virtually all organisms, and it is usually associated with two other enzymes found in this biosynthetic pathway, carbamylphosphate synthetase and/or aspartate transcarbamylase (ATCase). In the hyperthermophilic bacterium Aquifex aeolicus, ATCase and DHOase are noncovalently associated. Upon dissociation, ATCase keeps its activity entirely while DHOase is totally inactivated.

Activation of Latent Dihydroorotase from Aquifex aeolicus by Pressure.

Elevated hydrostatic pressure was used to probe conformational changes of Aquifex aeolicus dihydroorotase (DHO), which catalyzes the third step in de novo pyrimidine biosynthesis. The isolated protein, a 45-kDa monomer, lacks catalytic activity but becomes active upon formation of a dodecameric complex with aspartate transcarbamoylase (ATC). X-ray crystallographic studies of the isolated DHO and of the complex showed that association induces several major conformational changes in the DHO structure.

Plasma complement biomarkers distinguish multiple sclerosis and neuromyelitis optica spectrum disorder.

Background: Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are autoimmune inflammatory demyelinating diseases of the central nervous system. Although distinguished by clinicoradiological and demographic features, early manifestations can be similar complicating management. Antibodies against aquaporin-4 support the diagnosis of NMOSD but are negative in some patients.

Antimony/Graphitic Carbon Composite Anode for High-Performance Sodium-Ion Batteries.

Although the room-temperature rechargeable sodium-ion battery has emerged as an attractive alternative energy storage solution for large-scale deployment, major challenges toward practical sodium-ion battery technology remain including identification and engineering of anode materials that are both technologically feasible and economical. Herein, an antimony-based anode is developed by incorporating antimony into graphitic carbon matrices using low-cost materials and scalable processes. The composite anode exhibits excellent overall performance in terms of packing density, fast charge/discharge capability and cyclability, which is enabled by the conductive and compact graphitic network.

The comparative hemodynamic efficacy of lower limb muscles using transcutaneous electrical stimulation.

Background: Circulation in the limbs can be augmented using transcutaneous electrical stimulation devices. The optimum muscle stimulation sites for enhancement of vascular hemodynamic parameters have not been identified.

Methods: Seven suitable anatomic sites were identified within the right leg.

The diabetic foot: the importance of coordinated care.

Because of the severe morbidity and mortality associated with diabetes, diabetic foot care is an essential component of a peripheral vascular service. The goal of this article is to describe the vascular diabetic foot care pathway and how the coordinated foot care service for diabetic patients is delivered at King's College Hospital, London.

Intersubunit communication in the dihydroorotase-aspartate transcarbamoylase complex of Aquifex aeolicus.

Aspartate transcarbamoylase and dihydroorotase, enzymes that catalyze the second and third step in de novo pyrimidine biosynthesis, are associated in dodecameric complexes in Aquifex aeolicus and many other organisms. The architecture of the dodecamer is ideally suited to channel the intermediate, carbamoyl aspartate from its site of synthesis on the ATC subunit to the active site of DHO, which catalyzes the next step in the pathway, because both reactions occur within a large, internal solvent-filled cavity. Channeling usually requires that the reactions of the enzymes are coordinated so that the rate of synthesis of the intermediate matches its rate of utilization.

The mononuclear metal center of type-I dihydroorotase from Aquifex aeolicus.

Background: Dihydroorotase (DHO) is a zinc metalloenzyme, although the number of active site zinc ions has been controversial. E. coli DHO was initially thought to have a mononuclear metal center, but the subsequent X-ray structure clearly showed two zinc ions, α and β, at the catalytic site.

The impact of arterial pedal arch quality and angiosome revascularization on foot tissue loss healing and infrapopliteal bypass outcome.

Objective: This study evaluated the effect of pedal arch quality on the amputation-free survival and patency rates of distal bypass grafts and its direct impact on the rate of healing and time to healing of tissue loss after direct angiosome revascularization in patients with critical limb ischemia (CLI).

Methods: Between 2004 and 2011, patients undergoing distal bypass for CLI (Rutherford 4-6) were divided in groups taking into consideration the state of the pedal arch and direct angiosome revascularization (DAR) and non-DAR. Angiography was used to divide the pedal arch into three groups: complete pedal arch (CPA), incomplete pedal arch (IPA), and no pedal arch (NPA).

The smallest active carbamoyl phosphate synthetase was identified in the human gut archaeon Methanobrevibacter smithii.

The genome of the major intestinal archaeon Methanobrevibacter smithii contains a complex gene system coding for carbamoyl phosphate synthetase (CPSase) composed of both full-length and reduced-size synthetase subunits. These ammonia-metabolizing enzymes could play a key role in controlling ammonia assimilation in M. smithii, affecting the metabolism of gut bacterial microbiota, with an impact on host obesity.

FLASH knockdown sensitizes cells to Fas-mediated apoptosis via down-regulation of the anti-apoptotic proteins, MCL-1 and Cflip short.

FLASH (FLICE-associated huge protein or CASP8AP2) is a large multifunctional protein that is involved in many cellular processes associated with cell death and survival. It has been reported to promote apoptosis, but we show here that depletion of FLASH in HT1080 cells by siRNA interference can also accelerate the process. As shown previously, depletion of FLASH halts growth by down-regulating histone biosynthesis and arrests the cell cycle in S-phase.

Development of real-time assays for impedance-based detection of microbial double-stranded DNA targets: optimization and data analysis.

A real-time, label free assay was developed for microbial detection, utilizing double-stranded DNA targets and employing the next generation of an impedimetric sensor array platform designed by Sharp Laboratories of America (SLA). Real-time curves of the impedimetric signal response were obtained at fixed frequency and voltage for target binding to oligonucleotide probes attached to the sensor array surface. Kinetic parameters of these curves were analyzed by the integrated data analysis package for signal quantification.

Electronic properties of metal-arene functionalized graphene.

We have employed first-principles density-functional calculations to study the electronic characteristics of covalently functionalized graphene by metal-bis-arene chemistry. It is shown that functionalization with M-bis-arene (M = Ti, V, Cr, Mn, Fe) molecules leads to an opening in the bandgap of graphene (up to 0.81 eV for the Cr derivative), and as a result, transforms it from a semimetal to a semiconductor.

FAM129B/MINERVA, a novel adherens junction-associated protein, suppresses apoptosis in HeLa cells.

A recent proteomics study identified FAM129B or MINERVA as a target of the MAP kinase (Erk1/2) signaling cascade in human melanoma cells. Phosphorylation of the protein was found to promote cell invasion and the dissociation of the protein from the cell-cell junctions. Suppression of apoptosis during metastasis is a prerequisite for the survival and spread of cancer cells.

Efficient on-column conversion of IgG1 trisulfide linkages to native disulfides in tandem with Protein A affinity chromatography.

Protein trisulfide linkages are generated by the post-translational insertion of a sulfur atom into a disulfide bond. Molecular heterogeneity was detected in a recombinant IgG(1) monoclonal antibody (mAb) and attributed to the presence of a protein trisulfide moiety. The predominant site of trisulfide modification was the bond between the heavy and light chains.

Concentration of proteins and removal of solutes.

The dramatic advances in recombinant DNA and proteomics technology over the past decade have supported a tremendous growth in biologics applied to diagnostics, biomarkers, and commercial therapeutic markets. In particular, antibodies and fusion proteins have now become a main focus for a broad number of clinical indications, including neurology, oncology, and infectious diseases with projected increase in novel first-class molecules and biosimilar entities over the next several years. In line with these advances are the improved analytical, development, and small-scale preparative methods employed to elucidate biologic structure, function, and interaction.

Dihydroorotase from the hyperthermophile Aquifex aeolicus is activated by stoichiometric association with aspartate transcarbamoylase and forms a one-pot reactor for pyrimidine biosynthesis.

In prokaryotes, the first three enzymes in pyrimidine biosynthesis, carbamoyl phosphate synthetase (CPS), aspartate transcarbamoylase (ATC), and dihydroorotase (DHO), are commonly expressed separately and either function independently (Escherichia coli) or associate into multifunctional complexes (Aquifex aeolicus). In mammals the enzymes are expressed as a single polypeptide chain (CAD) in the order CPS-DHO-ATC and associate into a hexamer. This study presents the three-dimensional structure of the noncovalent hexamer of DHO and ATC from the hyperthermophile A.

Electrical detection of the temperature induced melting transition of a DNA hairpin covalently attached to gold interdigitated microelectrodes.

The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, manner. The structural state of the hairpin was assessed by measuring four different electronic properties of the GIME (capacitance, impedance, dissipation factor and phase angle) as a function of temperature from 25 degrees C to 80 degrees C. Consistent changes in all four electronic properties of the GIME were observed over this temperature range, and attributed to the transition of the attached single-stranded DNA (ssDNA) from an intramolecular, folded hairpin structure to a melted ssDNA.

The sole serine/threonine protein kinase and its cognate phosphatase from Aquifex aeolicus targets pyrimidine biosynthesis.

Serine/Threonine kinases participate in complex, interacting signaling pathways in eukaryotes, prokaryotes, and archae. While most organisms contain many different kinases, the extreme hyperthermophile, Aquifex aeolicus encodes a single hypothetical Ser/Thr kinase. A gene homologous to eukaryotic protein phosphatases overlaps the kinase gene by a single base pair.

Atlas-based segmentation of white matter tracts of the human brain using diffusion tensor tractography and comparison with classical dissection.

The technique of diffusion tensor tractography is gaining increasing prominence as a non-invasive method for studying the architecture of the white matter pathways in the human brain. Numerous studies have been published that attempt to identify or reconstruct particular pathways of interest. An atlas or map of all the pathways in the white matter would be particularly useful for providing detailed anatomical data that is not available in studies based on conventional MRI data.

Purification of an Fc-fusion biologic: clearance of multiple product related impurities by hydrophobic interaction chromatography.

An hydrophobic interaction chromatography step was developed for the large-scale production of an Fc-fusion biologic. Two abundant product-related impurities were separated from the active monomer using a Butyl resin and a simple step-wash and step-elution strategy. Capacity and resolution of the HIC step was optimal when sodium sulfate was employed as the lyotropic salt and pore size of the Butyl resin was 750A.

Protein kinase C modulates the up-regulation of the pyrimidine biosynthetic complex, CAD, by MAP kinase.

The multifunctional protein CAD initiates de novo pyrimidine biosynthesis in mammalian cells. CAD is activated by MAP kinase (Erk1/2) just prior to the S phase of the cell cycle, when the demand for pyrimidine nucleotides is greatest, and down-regulated as the cells emerge from S phase by protein kinase A (PKA) phosphorylation. MAP kinase phosphorylates Thr456, while PKA phosphorylates Ser1406 and Ser1859, although only Ser1406 is involved in regulation.