Self-Assembling Coiled-Coil Peptide Nanotubes with Biomolecular Cargo Encapsulation.

We report a coiled-coil trimeric peptide based on the known GCN4 zipper motif that self-assembles into nanotubes with diameters on the order of a few hundred nanometers to a micron. The dimensional morphology of these tubular structures was observed to be tunable by altering the properties of the buffer during assembly. Structural evidence from X-ray scattering and electron microscopy suggest that tube assembly takes place in structural tiers leading to a hexagonal close-packed arrangement of the coiled-coils.

A Library Approach to Cationic Amphiphilic Polyproline Helices that Target Intracellular Pathogenic Bacteria.

A number of pathogenic bacteria reproduce inside mammalian cells and are thus inaccessible to many antimicrobial drugs. Herein, we present a facile method to a focused library of antibacterial agents known as cationic amphiphilic polyproline helices (CAPHs). We identified three CAPHs from the library with superior cell penetration within macrophages and excellent antibacterial action against both Gram-positive and Gram-negative bacteria.

Accessing Three-Dimensional Crystals with Incorporated Guests through Metal-Directed Coiled-Coil Peptide Assembly.

Obtaining three-dimensional (3D) protein and peptide crystals on demand requires a precisely orchestrated hierarchical assembly of biopolymer building blocks. In this work, we disclose a metal-ion-mediated strategy to assemble trimeric coiled-coil peptides in a head-to-tail fashion into linear strands with interstrand interactions. This design led to hexagonal 3D peptide crystal formation within 30 min in the presence of divalent metal ions.

Dual Targeting of Intracellular Pathogenic Bacteria with a Cleavable Conjugate of Kanamycin and an Antibacterial Cell-Penetrating Peptide.

Bacterial infection caused by intracellular pathogens, such as Mycobacterium, Salmonella, and Brucella, is a burgeoning global health epidemic that necessitates urgent action. However, the therapeutic value of a number of antibiotics, including aminoglycosides, against intracellular pathogenic bacteria is compromised due to their inability to traverse eukaryotic membranes. For this significant problem to be addressed, a cleavable conjugate of the antibiotic kanamycin and a nonmembrane lytic, broad-spectrum antimicrobial peptide with efficient mammalian cell penetration, P14LRR, was prepared.

Antibacterial activity and therapeutic efficacy of Fl-P(R)P(R)P(L)-5, a cationic amphiphilic polyproline helix, in a mouse model of staphylococcal skin infection.

The antibacterial activities and therapeutic efficacy of the cationic, unnatural proline-rich peptide Fl-P(R)P(R)P(L)-5 were evaluated against multidrug-resistant Staphylococcus aureus in a mouse model of skin infection. Fl-P(R)P(R)P(L)-5 showed potent activity against all clinical isolates of S. aureus tested, including methicillin- and vancomycin-resistant S.

Scanning fluorescence correlation spectroscopy as a versatile tool to measure static and dynamic properties of soft matter systems.

We present the formalism and experimental implementation of scanning fluorescence correlation spectroscopy (SFCS) for the measurements of soft matter system structure and dynamics. We relate the SFCS function Fourier transform to the system intermediate scattering function and demonstrate how SFCS can be combined with specific labelling to measure the desired statistical and kinetic features of the system. Using DNA as a model polymer, we demonstrate the application of SFCS to measure (1) the static structure factor of the system, (2) polymer end-to-end distance distribution, and (3) polymer segmental dynamics in dilute and in dense solutions.

Targeting intracellular bacteria with an extended cationic amphiphilic polyproline helix.

An extended cationic and amphiphilic polyproline helix (CAPH) is described with a dual mode of action: effective cell penetration of human macrophages, and potent antimicrobial activity in vitro against both Gram-positive and negative pathogens, including Acinetobacter baumannii, Escherichia coli O157 and Bacillus anthracis. This dual action was successfully combined to clear pathogenic bacteria (Brucella and Salmonella) residing within macrophages.

Structure of DNA coils in dilute and semidilute solutions.

We apply scanning fluorescence correlation spectroscopy to study the structure of individual DNA coils in dilute and semidilute solutions. In dilute solutions, over two decades in length, from 0.6 to 46 μm, DNA behave as ideal chains, in agreement with theoretical predictions and in disagreement with prior experiments.

Hypernatremia in a patient treated with sodium polystyrene sulfonate.

Severe hyperkalemia requires urgent medical attention and correction in order to prevent arrhythmic complications. Sodium polystyrene sulfonate (SPS) is a cation exchange resin commonly used in the management of hyperkalemia. A recent review raised concerns regarding its effectiveness and potential adverse effects.

Kidney injury molecule-1 expression identifies proximal tubular injury in urate nephropathy.

Urate nephropathy in children is uncommon, occurring mostly in those who have undergone chemotherapy or radiotherapy. The characteristic obstruction of distal nephron tubules by uric acid precipitates is considered key to the subsequent parenchymal injury. Whether proximal tubular injury plays a role in urate nephropathy remains unclear.

Nephrotic range proteinuria: rare manifestation of scleroderma renal crisis.

The nephrotic range of proteinuria is uncommon in scleroderma renal crisis. This 46-yr-old woman with a medical history of scleroderma presented with very high blood pressure, a sudden elevation of serum creatinine, and proteinuria in the nephrotic range. Renal biopsy revealed onion-skin type of arterial changes with necrosis, confirming the presence of scleroderma nephropathy.