Biosensor incorporating cell barrier architectures for detecting <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> alpha toxin

Alpha toxin is a common virulent factor of Staphylococcus aureus and is believed to play crucial roles in pathogenicity induced by S. aureus. Alpha toxin is also known to induce permeability to endothelial cell monolayers in vitro due to the formation of interendothelial gaps. The present study is directed towards measuring alpha toxin using a whole-cell-based biosensor. The biosensor, consisting of a confluent monolayer of human umbilical vein endothelial cells (HUVECs) on a potassium ion-selective electrode, takes advantage of cell permeability dysfunction to detect the presence of small quantities of alpha toxin. When a confluent monolayer of cells was formed on the membrane surface, the response of the electrode toward the marker ion, potassium, was inhibited. Upon exposing this sensor to varying concentrations of alpha toxin for 20 min, an increase in sensor response to potassium was observed. The response thus obtained was indirectly related to the concentration of alpha toxin. The detection limit of this sensor for alpha toxin was found to be 0.1 ng/ml. Cell monolayers were stained with silver nitrate to quantify the formation of intercellular gaps as well as to study the effect of this toxin on HUVECs morphology. A strong positive correlation was observed between the response obtained from the biosensor and the area of the intercellular gaps. Silver staining also revealed the tendency of cells to round up upon being exposed to alpha toxin. Figure Measuring alpha toxin using a whole-cell-based biosensor     

The treatment of essential voice tremor with botulinum toxin A: A longitudinal case report

The purpose of this study was to evaluate the effects of bilateral botulinum toxin injection into the thyroarytenoid (TA) muscles of a patient with essential voice tremor. Acoustic and aerodynamic data were collected weekly over a 16-week period. Flexible nasolaryngoscopy was performed prior to injection and 2, 6, 10, and 16 weeks postinjection. Perceptual analyses of the acoustic and nasolaryngoscopic data were performed. A reduction in frequency tremor and, to a lesser extent, amplitude tremor was observed during the 1-10 week period. Estimated laryngeal resistance decreased after injection and was accompanied in perceptual measures by a reduction in vocal effort, laryngeal tremor, and supraglottic hyperfunction. Essential voice tremor can be successfully attenuated with bilateral percutaneous injection of botulinum toxin A into the vocalis muscle.     

Longitudinal Effects of Botulinum Toxin Injections on Voice-Related Quality of Life (V-RQOL) for Patients with Adductory Spasmodic Dysphonia

Adductory spasmodic dysphonia is a focal dystonia of laryngeal muscles. Patients with this disorder typically have severe vocal difficulties, with significant functional, social, and emotional consequences. There is no widely accepted cure for this condition, however, botulinum toxin injections of the thyroarytenoid muscles are considered by most voice clinicians to be the state of the art treatment. Based on extensive experience treating patients for adductory spasmodic dysphonia, we feel that traditional means of voice assessment do not adequately measure either the disease severity or the treatment outcomes. That is, listening to or acoustically analyzing limited phonatory samples does not capture the functional, social, and emotional consequences of this disorder. These consequences will be reflected in a patient's voice-related quality of life (V-RQOL). Using a validated voice outcomes instrument, the V-RQOL Measure, the purpose of this study was to quantify longitudinal changes in the V-RQOL of patients with adductory spasmodic dysphonia who are undergoing botulinum toxin injections. Twenty-seven consecutive new patients presenting with dysphonia to our institution during an 18-month period were diagnosed with adductory spasmodic dysphonia, and treated patients were evaluated prospectively using the V-RQOL Measure. Results indicated that (1) V-RQOL was initially very low for these patients, (2) botulinum toxin injections improved it significantly for each injection cycle studied, and (3) the magnitude of the treatment effect appears to change across injections.     

Graphdiyne Micromotors in Living Biomedia

Graphdiyne (GDY), a new kind of two-dimensional (2D) material, was combined with micromotor technology for “on-the-fly” operations in complex biomedia. Microtubular structures were prepared by template deposition on membrane templates, resulting in functional structures rich in sp and sp² carbons with highly conjugated π networks. This resulted in a highly increased surface area for a higher loading of anticancer drugs or enhanced quenching ability over other 2D based micromotors, such as graphene oxide (GO) or smooth tubular micromotors. High biocompatibility with almost 100 % cell viability was observed in cytotoxicity assays with moving micromotors in the presence of HeLa cells. On a first example, GDY micromotors loaded with doxorubicin (DOX) were used for pH responsive release and HeLa cancer cells killing. The use of affinity peptide engineered GDY micromotors was also illustrated for highly sensitive and selective fluorescent OFF–ON detection of cholera toxin B through specific recognition of the subunit B region of the target toxin. The new developments illustrated here offer considerable promise for the use of GDY as part of micromotors in living biosystems.     

A Label-Free Electrochemical Immunosensor for Clostridium Difficile Toxin B Based on One-Step Immobilization of Thionine in a Silica Matrix

A label-free amperometric immunosensor was fabricated to test clostridium difficile toxin B. Multi-walled carbon nanotubes were modified on the surface of a glassy carbon electrode by electrodeposition. A sol-gel method was developed to encapsulate thionine in an electrochemically induced three-dimensional porous silica matrix by a one-step process. Gold nanoparticle layers were constructed by covalent bonds and electrostatic adsorption with thionine. The clostridium difficile toxin B antibody was immobilized on the gold nanoparticles to construct the immunosensor. Cyclic voltammetry and differential pulse voltammetry demonstrated that the formation of antibody-antigen complexes decreased the peak current of thionine. The morphologies of the nanocomposites were investigated by scanning electron microscopy and ultraviolet-visible spectrometry. The electrode was shown to be sensitive and specific to detect clostridium difficile toxin B from 1.0 to 80.0 ng/mL with a limit of detection of 0.3 ng/mL.     

凝胶渗透净化–超高效液相色谱–串联质谱法测定橙汁中链格孢霉毒素

建立橙汁中4种链格孢霉毒素含量测定的凝胶渗透–超高效液相色谱–串联质谱检测方法。样品用乙腈提取后,用填料为Bio-Beads-S–X3的凝胶渗透色谱柱净化,净化时流动相采用乙酸乙酯–环己烷(体积比为1∶1),流速为5 mL/min,测定时用超高效液相反相C18色谱柱分离,甲醇–水系统梯度洗脱,采用电喷雾负离子源和多反应监测(MRM)模式定性和定量。4种链格孢霉毒素的最低定量限在0.0004～0.002 mg/kg范围内,加标回收率为78.9%～111.5%,测定结果的相对标准偏差均低于9.0%(n=10)。