The impact of head and neck radiation on airway management: a retrospective data review

Canadian Journal of Anesthesia/Journal canadien d'anesthésie -     

Development of a portable electrochemical loop mediated isothermal amplification (LAMP) device for detection of hepatitis B virus

The objective of this study was to develop a simple, inexpensive prototype device for rapid detection of hepatitis B virus (HBV). The device was able to simultaneously amplify, detect and quantify the target HBV DNA. The system was fabricated from a custom-made electrochemical set-up of which the temperature was thermostatically controlled by a water bath. Real-time monitoring of HBV DNA was accomplished by measuring the response of redox indicator in the reaction mixture. Concentration of HBV DNA in the samples was determined from the peak high ratio (PHR) and threshold time relationship. The signal was processed by sigmoidal model fitting to enhance the accuracy of the results. Key parameters including concentrations of redox indicator and reaction temperatures were optimized. Sensitivity and specificity of the method toward HBV DNA were evaluated. The prototype was capable of real-time amplification and detection of HBV DNA with concentration as low as 6.18 fg μl⁻¹. The test showed high specificity against HBV DNA. The system was also able to detect HBV positive serum directly with simple thermal pretreatment instead of tedious DNA extraction. The electrochemical set-up was compatible with microfluidic platforms and can be readily adapted for efficient and high throughput point-of-care (POC) diagnosis of HBV.

A novel prototype device using LAMP and electrochemical drop cell set-up for rapid detection of hepatitis B virus.     

Changing Blue Fluorescent Protein to Green Fluorescent Protein Using Chemical RNA Editing as a Novel Strategy in Genetic Restoration

Using the transition from cytosine of BFP (blue fluorescent protein) gene to uridine of GFP (green fluorescent protein) gene at position 199 as a model, we successfully controlled photochemical RNA editing to effect site‐directed deamination of cytidine (C) to uridine (U). Oligodeoxynucleotides (ODNs) containing 5′‐carboxyvinyl‐2′‐deoxyuridine (^CVU) were used for reversible photoligation, and single‐stranded 100‐nt BFP DNA and in vitro‐transcribed full‐length BFP mRNA were the targets. Photo‐cross‐linking with the responsive ODNs was performed using UV (366 nm) irradiation, which was followed by heat treatment, and the cross‐linked nucleotide was cleaved through photosplitting (UV, 312 nm). The products were analyzed using restriction fragment length polymorphism (RFLP) and fluorescence measurements. Western blotting and fluorescence‐analysis results revealed that in vitro‐translated proteins were synthesized from mRNAs after site‐directed RNA editing. We detected substantial amounts of the target‐base‐substituted fragment using RFLP and observed highly reproducible spectra of the transition‐GFP signal using fluorescence spectroscopy, which indicated protein stability. ODNc restored approximately 10% of the C‐to‐U transition. Thus, we successfully used non‐enzymatic site‐directed deamination for genetic restoration in vitro. In the near future, in vivo studies that include cultured cells and model animals will be conducted to treat genetic disorders.     

Size Effects in Internal Friction of Nanocrystalline Aluminum Films

Al thin film is extensively used in micro-electromechanical systems (MEMS) and electronic interconnections; however, most previous research has concentrated on their quasi-static properties and applied their designs on larger scales. The present study designed a paddle-like cantilever specimen with metal films deposited on the upper surface to investigate the quasi-static properties of Al thin film at room temperature under high vacuum conditions at microscopic scales. Energy loss was determined using a decay technique in the oscillation amplitude of a vibrating structure following resonant excitation. Grain size and film thickness size were strictly controlled considering the quasi-static properties of the films. This study found that the internal friction of ultra-thin and thin Al films was more dependent on the grain boundaries than film thickness.     

Voluntary Cough Airflow Differentiates Safe Versus Unsafe Swallowing in Amyotrophic Lateral Sclerosis

Dysphagia and aspiration are prevalent in amyotrophic lateral sclerosis (ALS) and contribute to malnutrition, aspiration pneumonia, and death. Early detection of at risk individuals is critical to ensure maintenance of safe oral intake and optimal pulmonary function. We therefore aimed to determine the discriminant ability of voluntary cough airflow measures in detecting penetration/aspiration status in ALS patients. Seventy individuals with ALS (El-Escorial criteria) completed voluntary cough spirometry testing and underwent a standardized videofluoroscopic swallowing evaluation (VFSE). A rater blinded to aspiration status derived six objective measures of voluntary cough airflow and evaluated airway safety using the penetration–aspiration scale (PAS). A between groups ANOVA (safe vs. unsafe swallowers) was conducted and sensitivity, specificity, area under the curve (AUC) and likelihood ratios were calculated. VFSE analysis revealed 24 penetrator/aspirators (PAS ≥3) and 46 non-penetrator/aspirators (PAS ≤2). Cough volume acceleration (CVA), peak expiratory flow rise time (PEFRT), and peak expiratory flow rate (PEFR) were significantly different between airway safety groups (p < 0.05) and demonstrated significant discriminant ability to detect the presence of penetration/aspiration with AUC values of: 0.85, 0.81, and 0.78, respectively. CVA <45.28 L/s/s, PEFR <3.97 L/s, and PEFRT >76 ms had sensitivities of 91.3, 82.6, and 73.9 %, respectively, and specificities of 82.2, 73.9, and 78.3 % for identifying ALS penetrator/aspirators. Voluntary cough airflow measures identified ALS patients at risk for penetration/aspiration and may be a valuable screening tool with high clinical utility.     

Crystal structure and functional analysis of tetracenomycin ARO/CYC: implications for cyclization specificity of aromatic polyketides

Polyketides are a class of natural products with highly diverse chemical structures and pharmaceutical activities. Polyketide cyclization, promoted by the aromatase/cyclase (ARO/CYC), helps diversify aromatic polyketides. How the ARO/CYC promotes highly specific cyclization is not well understood because of the lack of a first-ring ARO/CYC structure. The 1.9 A crystal structure of Tcm ARO/CYC reveals that the enzyme belongs to the Bet v1-like superfamily (or STAR domain family) with a helix-grip fold, and contains a highly conserved interior pocket. Docking, mutagenesis, and an in vivo assay show that the size, shape, and composition of the pocket are important to orient and specifically fold the polyketide chain for C9-C14 first-ring and C7-C16 second-ring cyclizations. Two pocket residues, R69 and Y35, were found to be essential for promoting first- and second-ring cyclization specificity. Different pocket residue mutations affected the polyketide product distribution. A mechanism is proposed based on the structure-mutation-docking results. These results strongly suggest that the regiospecific cyclizations of the first two rings and subsequent aromatizations take place in the interior pocket. The chemical insights gleaned from this work pave the foundation toward defining the molecular rules for the ARO/CYC cyclization specificity, whose rational control will be important for future endeavors in the engineered biosynthesis of novel anticancer and antibiotic aromatic polyketides.     

Detection of human apolipoprotein B polymorphic species with one monoclonal antibody (BIP 45) against low density lipoprotein. Influence of this polymorphism on lipid levels and coronary artery stenosis

The immunoreactivity of apolipoprotein B (apo B) in plasma samples obtained from a variety of subjects was analysed by non-competitive ELISA with a polyclonal and a monoclonal (BIP 45) anti-LDL antibody. Three populations were tested: the first, comprising 244 healthy male volunteers, provided reference values; the second consisted of a population undergoing coronary angiography (n = 88) and was divided into a subgroup with (n = 64) and without (n = 24) coronary artery disease (CAD); the third was made up of 56 patients with heterozygous familial hypercholesterolemia. Total apo B (measured with the polyclonal antibody) was increased in the populations with CAD and in the heterozygous familial hypercholesterolemic subjects compared to the reference population. When monoclonal antibody BIP 45 was used in the non-competitive ELISA, three different patterns emerged in each population, corresponding to weak, intermediate and strong binding of the particles containing apo B to the monoclonal antibody. This may result from genetic polymorphism of apo B, and in the reference population the data fit a model consisting of two co-dominant apo B alleles (BIP(-) and BIP(+]; the 3 subpopulations then correspond to the 2 homozygotes and the heterozygote. The number of patients whose particles bound weakly to monoclonal BIP 45 antibody was low in the CAD population, while intermediate binding was increased in this group. Nevertheless, when the analysis of variance of allele BIP(-) was studied no significant difference between groups was established. This finding indicates that the genetic difference in apo B detected by BIP 45 may not be significant in the development of CAD. Furthermore, the apo B genetic polymorphism detected by BIP 45 is not associated with a particular lipoprotein level in the reference population.