Oriented Cell Growth on Self-Assembled Bacteriophage M13 Thin Films

Fibrillar M13 bacteriophages were used as basic building blocks to generate thin films with aligned nanogrooves, which, upon chemical grafting with RGD peptides, guide cell alignment and orient the cell outgrowth along defined directions

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Immobilization of Escherichia coli Cells by Use of the Antimicrobial Peptide Cecropin P1

An immobilization scheme for bacterial cells is described, in which the antimicrobial peptide cecropin P1 was used to trap Escherichia coli K-12 and O157:H7 cells on microtiter plate well surfaces. Cecropin P1 was covalently attached to the well surfaces, and E. coli cells were allowed to bind to the peptide-coated surface. The immobilized cells were detected colorimetrically with an anti-E. coli antibody-horseradish peroxidase conjugate. Binding curves were obtained in which the signal intensities were dependent upon the cell concentration and upon the amount of peptide attached to the well surface. After normalization for the amount of peptide coupled to the surface and the relative binding affinity of the antibody for each strain, the binding data were compared, which indicated that there was a strong preference for E. coli O157:H7 over E. coli K-12. The cells could be immobilized reproducibly at pH values ranging from 5 to 10 and at ionic strengths up to 0.50 M

Orientation difference of chemically immobilized and physically adsorbed biological molecules on polymers detected at the solid/liquid interfaces in situ

A surface sensitive second order nonlinear optical technique, sum frequency generation vibrational spectroscopy, was applied to study peptide orientation on polymer surfaces, supplemented by a linear vibrational spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy. Using the antimicrobial peptide Cecropin P1 as a model system, we have quantitatively demonstrated that chemically immobilized peptides on polymers adopt a more ordered orientation than less tightly bound physically adsorbed peptides. These differences were also observed in different chemical environments, for example, air versus water. Although numerous studies have reported a direct correlation between the choice of immobilization method and the performance of an attached biological molecule, the lack of direct biomolecular structure and orientation data has made it difficult to elucidate the relationship between structure, orientation, and function at a surface. In this work, we directly studied the effect of chemical immobilization method on biomolecular orientation/ordering, an important step for future studies of biomolecular activity. The methods for orientation analysis described within are also of relevance to understanding biosensors, biocompatibility, marine-antifouling, membrane protein functions, and antimicrobial peptide activities

RNA aptasensor for rapid detection of natively folded type A botulinum neurotoxin

A surface plasmon resonance based RNA aptasensor for rapid detection of natively folded type A botulinum neurotoxin is reported. Using detoxified recombinant type A botulinum neurotoxin as the surrogate, the aptasensor detects active toxin within 90 min. The detection limit of the aptasensor in phosphate buffered saline, carrot juice, and fat free milk is 5.8 ng/ml, 20.3 ng/ml and 23.4 ng/ml, respectively, while that in 5-fold diluted human serum is 22.5 ng/ml. Recovery of toxin from disparate sample matrices are within 91-116%. Most significant is the ability of this aptasensor to effectively differentiate the natively folded toxin from denatured, inactive toxin, which is important for homeland security surveillance and threat assessment. The aptasensor is stable for more than 30 days and over 400 injections/regeneration cycles. Such an aptasensor holds great promise for rapid detection of active botulinum neurotoxin for field surveillance due to its robustness, stability and reusability

Aqueous Processing and Fiber Spinning of Recombinant Spider Silks

Spiders have captured the interest of scientists for many years because spider silks are among the toughest materials, having properties that surpass some man-made synthetic materials. Spinning recombinant silk to duplicate those properties has proved to be extremely difficult. This is the first known report of spinning recombinant silk fibers in an aqueous environment. The method seeks to keep the protein soluble throughout the process, not unlike the way the spider stores and spins silk. Recombinant silk proteins were produced by bacterial fermentation in which the cell pellets were lyophilized and lysed with organic acid. Silk protein was purified from the lysate by chromatography and processed in dilute denaturing buffer into a fiber spinning solution. Circular dichroism measurements of the silk solutions revealed an increase in β-sheet content as a function of time. Time-dependent self-association of silk protein was monitored in solution by dynamic light scattering. Furthermore, the observed increase in β-sheet content and self-association appear to be required for fiber formation. Recombinant silk fibers were 10−60 μm in diameter, water insoluble, and birefringent, indicating molecular orientation within the fiber