Heme-protein vibrational couplings in cytochrome c provide a dynamic link that connects the heme-iron and the protein surface

The active site of cytochrome c (Cyt c) consists of a heme covalently linked to a pentapeptide segment (Cys-X-X-Cys-His), which provides a link between the heme and the protein surface, where the redox partners of Cyt c bind. To elucidate the vibrational properties of heme c, nuclear resonance vibrational spectroscopy (NRVS) measurements were performed on (57)Fe-labeled ferric Hydrogenobacter thermophilus cytochrome c(552), including (13)C(8)-heme-, (13)C(5)(15)N-Met-, and (13)C(15)N-polypeptide (pp)-labeled samples, revealing heme-based vibrational modes in the 200- to 450-cm(-1) spectral region. Simulations of the NRVS spectra of H. thermophilus cytochrome c(552) allowed for a complete assignment of the Fe vibrational spectrum of the protein-bound heme, as well as the quantitative determination of the amount of mixing between local heme vibrations and pp modes from the Cys-X-X-Cys-His motif. These results provide the basis to propose that heme-pp vibrational dynamic couplings play a role in electron transfer (ET) by coupling vibrations of the heme directly to vibrations of the pp at the protein-protein interface. This could allow for the direct transduction of the thermal (vibrational) energy from the protein surface to the heme that is released on protein/protein complex formation, or it could modulate the heme vibrations in the protein/protein complex to minimize reorganization energy. Both mechanisms lower energy barriers for ET. Notably, the conformation of the distal Met side chain is fine-tuned in the protein to localize heme-pp mixed vibrations within the 250- to 400-cm(-1) spectral region. These findings point to a particular orientation of the distal Met that maximizes ET.     

Molecular basis of Tank-binding kinase 1 activation by transautophosphorylation

Tank-binding kinase (TBK)1 plays a central role in innate immunity: it serves as an integrator of multiple signals induced by receptor-mediated pathogen detection and as a modulator of IFN levels. Efforts to better understand the biology of this key immunological factor have intensified recently as growing evidence implicates aberrant TBK1 activity in a variety of autoimmune diseases and cancers. Nevertheless, key molecular details of TBK1 regulation and substrate selection remain unanswered. Here, structures of phosphorylated and unphosphorylated human TBK1 kinase and ubiquitin-like domains, combined with biochemical studies, indicate a molecular mechanism of activation via transautophosphorylation. These TBK1 structures are consistent with the tripartite architecture observed recently for the related kinase IKKβ, but domain contributions toward target recognition appear to differ for the two enzymes. In particular, both TBK1 autoactivation and substrate specificity are likely driven by signal-dependent colocalization events.     

Structural investigations of a Podoviridae streptococcus phage C1, implications for the mechanism of viral entry

The Podoviridae phage C1 was one of the earliest isolated bacteriophages and the first virus documented to be active against streptococci. The icosahedral and asymmetric reconstructions of the virus were calculated using cryo-electron microscopy. The capsid protein has an HK97 fold arranged into a T = 4 icosahedral lattice. The C1 tail is terminated with a φ29-like knob, surrounded by a skirt of twelve long appendages with novel morphology. Several C1 structural proteins have been identified, including a candidate for an appendage. The crystal structure of the knob has an N-terminal domain with a fold observed previously in tube forming proteins of Siphoviridae and Myoviridae phages. The structure of C1 suggests the mechanisms by which the virus digests the cell wall and ejects its genome. Although there is little sequence similarity to other phages, conservation of the structural proteins demonstrates a common origin of the head and tail, but more recent evolution of the appendages.     

Dexamethasone exposure and asparaginase antibodies affect relapse risk in acute lymphoblastic leukemia

We have previously hypothesized that higher systemic exposure to asparaginase may cause increased exposure to dexamethasone, both critical chemotherapeutic agents for acute lymphoblastic leukemia. Whether interpatient pharmaco-kinetic differences in dexamethasone contribute to relapse risk has never been studied. The impact of plasma clearance of dexamethasone and anti-asparaginase antibody levels on risk of relapse was assessed in 410 children who were treated on a front-line clinical trial for acute lymphoblastic leukemia and were evaluable for all pharmacologic measures, using multivariate analyses, adjusting for standard clinical and biologic prognostic factors. Dexamethasone clearance (mean ± SD) was higher (P = 3 × 10(-8)) in patients whose sera was positive (17.7 ± 18.6 L/h per m(2)) versus nega-tive (10.6 ± 5.99 L/h per m(2)) for anti-asparaginase antibodies. In multivariate analyses, higher dexamethasone clearance was associated with a higher risk of any relapse (P = .01) and of central nervous system relapse (P = .014). Central nervous system relapse was also more common in patients with anti-asparaginase antibodies (P = .019). In conclusion, systemic clearance of dexamethasone is higher in patients with anti-asparaginase antibodies. Lower exposure to both drugs was associated with an increased risk of relapse.     

Microbial contamination assessment of cryostored autogenous cranial bone flaps: should bone biopsies or swabs be performed?

Background

Autogenous cranioplasty infection requiring bone flap removal is under-recognised as a major complication causing significant morbidity. Microbial contamination of stored bone flaps may be a significant contributing factor. Current infection control practices and storage procedures vary. It is not known whether ‘superficial’ swabs or bone cultures provide a more accurate assessment.

Method

Twenty-five skull flaps that were cryo-stored for more than 6 months were studied. Two swab samples (superficial and deep) and a bone biopsy sample were taken from each skull flap sample and cultured. Half blood agar and half chocolate agar plates were inoculated with the swabs for anaerobic and aerobic cultures respectively. The bone biopsy samples were cultured in brain-heart broth and subcultured similar to the swabs for 5 days.

Results

Incidence of microbial contamination was 20 % in the bone flaps studied. One swab culture and five bone biopsy cultures were positive for bacterial growth, all of which contained Propionibacterium acnes (p?=?0.014). Positive cultures were from bone flaps stored less than 18 months, whereas no growth was obtained from bone flaps that were stored longer (p?=?0.014).

Conclusions

Bone biopsy culture is a more sensitive technique of assessing microbial contamination of cryo-stored autogenous bone flaps than swab cultures. The clinical implications of in vitro demonstration of microbial contamination require further study.     

The science behind the 7th edition Tumour, Node, Metastasis staging system for lung cancer

The Tumour, Node, Metastasis (TNM) system for classifying lung cancer is the cornerstone of modern lung cancer treatment and underpins comparative research; yet is continuously evolving through updated revisions. The recently published Union for International Cancer Control 7th Edition TNM Classification for lung cancer addresses many of its predecessor's shortcomings and has been subject to rigorous evidence-based methodology. It is based on a retrospective analysis of over 80 000 lung cancer patients treated between 1990 and 2000 carried out by the International Association for the Study of Lung Cancer. The dataset was truly international and included patients treated by all modalities. Extensive internal and external validation of the findings has ensured that the recommendations are robust and generalizable. For the first time, a single classification system has been shown to be applicable not only to non-small cell lung cancer, but also to be of prognostic significance in small cell lung cancer and bronchopulmonary carcinoid tumours. We review the history of the Union for International Cancer Control TNM staging system, the changes in the most recent 7th edition and the strength of the scientific basis motivating these changes. Limitations of the current staging edition are explored, post-publication independent validation studies are reviewed, and the future of TNM staging for lung cancer is discussed.     

Potential applications and human biosafety of nanomaterials used in nanomedicine

With the rapid development of nanotechnology, potential applications of nanomaterials in medicine have been widely researched in recent years. Nanomaterials themselves can be used as image agents or therapeutic drugs, and for drug and gene delivery, biological devices, nanoelectronic biosensors or molecular nanotechnology. As the composition, morphology, chemical properties, implant sites as well as potential applications become more and more complex, human biosafety of nanomaterials for clinical use has become a major concern. If nanoparticles accumulate in the human body or interact with the body molecules or chemical components, health risks may also occur. Accordingly, the unique chemical and physical properties, potential applications in medical fields, as well as human biosafety in clinical trials are reviewed in this study. Finally, this article tries to give some suggestions for future work in nanomedicine research. Copyright © 2017 John Wiley & Sons, Ltd.