Quantitative Endogenous Polyamine Analysis via Capillary Electrophoresis/Mass Spectrometry: Characterization and Practical Considerations.

Commonly used analytical techniques for polyamine analysis, including derivatization and mixed-mode liquid chromatography (LC), have inherent disadvantages. Capillary electrophoresis (CE) is uniquely suited to analyze small, highly charged molecules because analytes are separated on the basis of their electrophoretic mobility, not polarity or association with a stationary phase. Microfluidic CE-mass spectrometry (mCE-MS) is a relatively recent addition to commercially available CE offerings that streamlines traditional CE-MS interfacing and has the potential to improve upon classic CE challenges to robustness and reproducibility.

The longevity factor spermidine is part of a highly heritable complex erythrocyte phenotype associated with longevity.

Extreme longevity in humans is known to be a heritable trait. In a well-established twin erythrocyte metabolomics and proteomics database, we identified the longevity factor spermidine and a cluster of correlated molecules with high heritability estimates. Erythrocyte spermidine is 82% heritable and significantly correlated with 59 metabolites and 22 proteins.

Early Infant Male Circumcision Decisions in Zambia: Demographic and Familial Influences.

Public health initiatives in Zambia encourage the uptake of early infant male circumcision (EIMC) as an HIV prevention strategy. This study assessed EIMC parental decision-making during perinatal care in Lusaka, Zambia, focusing on the influence of sociodemographic factors, family, and friends. A longitudinal pilot perinatal intervention, Like Father Like Son (LFLS), was implemented among 300 couples attending antenatal clinics in four urban community health centers.

DNAzyme-Catalyzed Site-Specific N-Acylation of DNA Oligonucleotide Nucleobases.

We used in vitro selection to identify DNAzymes that acylate the exocyclic nucleobase amines of cytidine, guanosine, and adenosine in DNA oligonucleotides. The acyl donor was the 2,3,5,6-tetrafluorophenyl ester (TFPE) of a 5'-carboxyl oligonucleotide. Yields are as high as >95 % in 6 h.

Near Room-Temperature Intrinsic Exchange Bias in an Fe Intercalated ZrSe Spin Glass.

Some magnetic systems display a shift in the center of their magnetic hysteresis loop away from zero field, a phenomenon termed exchange bias. Despite the extensive use of the exchange bias effect, particularly in magnetic multilayers, for the design of spin-based memory/electronics devices, a comprehensive mechanistic understanding of this effect remains a longstanding problem. Recent work has shown that disorder-induced spin frustration might play a key role in exchange bias, suggesting new materials design approaches for spin-based electronic devices that harness this effect.

Concerted Proton-Coupled Electron Transfer to a Graphite Adsorbed Metalloporphyrin Occurs by Band to Bond Electron Redistribution.

Surface immobilized catalysts are highly promising candidates for a range of energy conversion reactions, and atomistic mechanistic understanding is essential for their rational design. Cobalt tetraphenylporphyrin (CoTPP) nonspecifically adsorbed on a graphitic surface has been shown to undergo concerted proton-coupled electron transfer (PCET) in aqueous solution. Herein, density functional theory calculations on both cluster and periodic models representing π-stacked interactions or axial ligation to a surface oxygenate are performed.

Structural evidence for intermediates during O formation in photosystem II.

In natural photosynthesis, the light-driven splitting of water into electrons, protons and molecular oxygen forms the first step of the solar-to-chemical energy conversion process. The reaction takes place in photosystem II, where the MnCaO cluster first stores four oxidizing equivalents, the S to S intermediate states in the Kok cycle, sequentially generated by photochemical charge separations in the reaction center and then catalyzes the O-O bond formation chemistry. Here, we report room temperature snapshots by serial femtosecond X-ray crystallography to provide structural insights into the final reaction step of Kok's photosynthetic water oxidation cycle, the S→[S]→S transition where O is formed and Kok's water oxidation clock is reset.

XFEL serial crystallography reveals the room temperature structure of methyl-coenzyme M reductase.

Methyl-Coenzyme M Reductase (MCR) catalyzes the biosynthesis of methane in methanogenic archaea, using a catalytic Ni-centered Cofactor F430 in its active site. It also catalyzes the reverse reaction, that is, the anaerobic activation and oxidation, including the cleavage of the CH bond in methane. Because methanogenesis is the major source of methane on earth, understanding the reaction mechanism of this enzyme can have massive implications in global energy balances.

Enhanced and Selective MALDI-MS Detection of Peptides via the Nanomaterial-Dependent Coffee Ring Effect.

Nanomaterials have been explored as alternative matrices in MALDI-MS to overcome some of the limitations of conventional matrices. Recently, we demonstrated a new means by which nanomaterials can improve peptide ionization and detection in MALDI-MS analyses by exploiting the tendency of nanomaterials to form "coffee rings" upon drying from liquids. In the current work, we investigate how nanomaterial size and composition affect the signal enhancement of peptides through the coffee-ring effect.

Graphite Conjugation Eliminates Redox Intermediates in Molecular Electrocatalysis.

The efficient interconversion of electrical and chemical energy requires the intimate coupling of electrons and small-molecule substrates at catalyst active sites. In molecular electrocatalysis, the molecule acts as a redox mediator which typically undergoes oxidation or reduction in a separate step from substrate activation. These mediated pathways introduce a high-energy intermediate, cap the driving force for substrate activation at the reduction potential of the molecule, and impede access to high rates at low overpotentials.

Strong Electronic Coupling of Molecular Sites to Graphitic Electrodes via Pyrazine Conjugation.

Glassy carbon electrodes were functionalized with redox-active moieties by condensation of o-phenylenediamine derivatives with o-quinone sites native to graphitic carbon surfaces. Electrochemical and spectroscopic investigations establish that these graphite-conjugated catalysts (GCCs) exhibit strong electronic coupling to the electrode, leading to electron transfer (ET) behavior that diverges fundamentally from that of solution-phase or surface-tethered analogues. We find that (1) ET is not observed between the electrode and a redox-active GCC moiety regardless of applied potential.

Pseudo-fivefold diffraction symmetries in tetrahedral packing.

We review the way in which atomic tetrahedra composed of metallic elements pack naturally into fused icosahedra. Orthorhombic, hexagonal, and cubic intermetallic crystals based on this packing are all shown to be united in having pseudo-fivefold rotational diffraction symmetry. A unified geometric model involving the 600-cell is presented: the model accounts for the observed pseudo-fivefold symmetries among the different Bravais lattice types.

Common bile duct stenosis and pancreatitis in Kawasaki disease: two cases and a review of the literature.

We report 2 children with Kawasaki disease, who developed pancreatitis and common bile duct abnormalities. After reviewing the literature, we conclude that Kawasaki disease may lead to such changes as a result of the underlying vasculitis characterizing this disease, or of direct inflammation of the biliary tree.

[Public health ethics as applied ethics. Debates on the legitimacy and limits of public health engagement].

Public health engagement is strongly connected to a relatively new concept of health promotion. This concept focuses on a general health-related attitude which is to be established through the networking of multiple institutional and private actors. Hence the practical realization of this concept leads to extensive transitions concerning the institutions and health-related interventions involved.

Reflux patterns in the ovarian and hypogastric veins in patients with varicose veins and signs of pelvic venous incompetence.

Patients with varicose veins who also had clinical and/or duplex ultrasound findings suspicious of pelvic venous incompetence (PVI) underwent selective retrograde catheter phlebography of the pelvic veins. One hundred and one patients (all female, mean age 49.3 years) underwent selective phlebography of the pelvic veins.

Clinical findings and lung pathology in children with cystic fibrosis.

Cystic fibrosis pulmonary disease is assessed by pulmonary function tests, arterial blood gases, and chest X-rays, but the correlation with lung pathology is unknown. We reviewed the clinical findings and lung pathology of 21 cystic fibrosis patients who had lung transplant. Pulmonary function tests, Brasfield scores, arterial blood gases, and age were correlated with lung pathology.

Operative treatment of supracondylar fractures of the humerus in children. The consequences of pin placement.

Background: The commonly accepted treatment of displaced supracondylar fractures of the humerus in children is fracture reduction and percutaneous pin fixation; however, there is controversy about the optimal placement of the pins. A crossed-pin configuration is believed to be mechanically more stable than lateral pins alone; however, the ulnar nerve can be injured with the use of a medial pin. It has not been proved that the added stability of a medial pin is clinically necessary since, in young children, pin fixation is always augmented with immobilization in a splint or cast.

Reliability of a modified Gartland classification of supracondylar humerus fractures.

Fracture-classification systems are used to recommend treatment and predict outcomes. In this study, a modified Gartland classification system of supracondylar humerus fractures in children was assessed for intraobserver and interobserver variability. Five observers classified radiographs of 50 consecutive children with extension supracondylar humerus fractures on three separate occasions.

The radiological approach to precocious puberty.

Precocious puberty is caused by a heterogeneous group of disorders, which range from idiopathic to malignant tumours. The radiologist's role is to help: (1) differentiate precocious puberty from pubertal variants; (2) identify the underlying cause of precocity if present; and (3) assess for effectiveness of treatment. This pictorial review discusses the types of precocious puberty and their underlying aetiologies, differentiates precocious puberty from pubertal variants and illustrates the appropriate imaging evaluation for the patient diagnosed with precocious puberty.

Complications of cancer therapy in children: a radiologist's guide.

As advances in cancer therapy improve the prognosis of patients with childhood malignancies, awareness of the consequences of treatment methods assumes increasing importance. All cancer treatment modalities are associated with toxic effects, and the spectrum of therapy-induced complications involves all organ systems. Radiologists have a pivotal role in detecting these sequelae, which can be categorized by the affected organ system and by whether they occur (a) at diagnosis or during initial therapy or (b) after the completion of treatment.

Variability in measurement of acetabular index in normal and dysplastic hips, before and after reduction.

This study examined the variability in the measurement of the acetabular index (AI) in normal and dysplastic hips, both before and after reduction. This variability for dysplastic hips is greater than that of normal hips. The variability is greater before an open or closed reduction than after reduction, and the variability after an open reduction is nearly 3 times greater than after a closed reduction.