Formation of gel and solid phases in acrylic cuvettes upon exposure to DMSO, oxygen and light: implications for fluorescence spectroscopy.

We here report the formation of a turbid-gel phase in acrylic cuvettes upon exposure to pure Dimethyl Sulfoxide (DMSO) at room temperature. The observed phenomenon occurred over a 10 h to 14 h incubation in the presence of environmental oxygen. After the turbid gel was removed from the cuvette, it became a white solid exhibiting unique emission behavior.

Aβ Amyloid Fibers Drastically Alter the Topography and Mechanical Properties of Lipid Membranes.

Alzheimer's disease (AD) is related to the fibrillation of the Aβ peptides at neuronal membranes, a process that depends on the lipid composition and may impart different physical states to the membrane. In the present work, we study the properties of the Aβ peptide when mixed with a zwitterionic lipid (DMPC), using the Langmuir monolayer technique as an approach to control membrane physical conditions. First, we build on previous characterizations of pure Aβ monolayers and observe that, in addition to high shear, these films present a pronounced compressional hysteresis.

Interfacial Aβ fibril formation is modulated by the disorder-order state of the lipids: The concept of the physical environment as amyloid inductor in biomembranes.

The behavior of amphiphilic molecules such as lipids, peptides and their mixtures at the air/water interface allow us to evaluate and visualize the arrangement formed in a confined and controlled surface area. We have studied the surface properties of the zwitterionic DPPC lipid and Aβ(1-40) amyloid peptide in mixed films at different temperatures (from 15 to 40 °C). In this range of temperature the surface properties of pure Aβ(1-40) peptide remained unchanged, whereas DPPC undergoes its characteristic liquid-expanded → liquid-condensed bidimensional phase transition that depends on the temperature and lateral pressure.

Melittin-solid phospholipid mixed films trigger amyloid-like nano-fibril arrangements at air-water interface.

We used the Langmuir monolayers technique to study the surface properties of melittin toxin mixed with either liquid-condensed DSPC or liquid-expanded POPC phospholipids. Pure melittin peptide forms stable insoluble monolayers at the air-water interface without interacting with Thioflavin T (Th-T), a sensitive probe to detect protein amyloid formation. When melittin peptide is mixed with DSPC lipid at 50 % of peptide area proportion at the surface, we observed the formation of fibril-like structures detected by Brewster angle microscopy (BAM), but they were not observable with POPC.

Gangliosides smelt nanostructured amyloid Aβ(1-40) fibrils in a membrane lipid environment.

Gangliosides induced a smelting process in nanostructured amyloid fibril-like films throughout the surface properties contributed by glycosphingolipids when mixed with 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC)/Aβ(1-40) amyloid peptide. We observed a dynamical smelting process when pre-formed amyloid/phospholipid mixture is laterally mixed with gangliosides. This particular environment, gangliosides/phospholipid/Aβ(1-40) peptide mixed interfaces, showed complex miscibility behavior depending on gangliosides content.

Stitching together a nm thick peptide-based semiconductor sheet using UV light.

Langmuir monolayer allows for a two-dimensional nano-scale organization of amphiphilic molecules. We have adapted this technique to measure lateral and transverse conductivity in confined peptide nanosheets for the first time. We reported that two retro-isomers amphipathic peptides form stable monolayers showing a semiconductor-like behavior.

Aβ-Amyloid Fibrils Are Self-Triggered by the Interfacial Lipid Environment and Low Peptide Content.

We studied the surface properties of Aβ(1-40) amyloid peptides mixed with 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) (liquid state) or 1,2-disteraoyl-phosphatidylcholine (DSPC) (solid state) phospholipids by using nanostructured lipid/peptide films (Langmuir monolayers). Pure Aβ(1-40) amyloid peptides form insoluble monolayers without forming fibril-like structures. In a lipid environment [phospholipid/Aβ(1-40) peptide mixtures], we observed that both miscibility and stability of the films depend on the peptide content.

Experimental diabetes impairs maternal reproductive performance in pregnant Wistar rats and their offspring.

Unlabelled: The aim of this study was to determine the effect of mild hyperglycemia on metabolism during pregnancy, the maternal reproductive performance, and the characteristics of the offspring in neonatal mild diabetic-induced Wistar rats. The experimental diabetes model was generated by neonatal streptozotocin administration (100 mg of streptozotocin/Kg bw/sc) in female Wistar rats. At adulthood, the control and diabetic group were mated.

Concentration of Zinc, Copper, Iron, Calcium, and Magnesium in the Serum, Tissues, and Urine of Streptozotocin-Induced Mild Diabetic Rat Model.

The present study aimed to investigate, in the streptozotocin-induced mild diabetic rat model, the zinc (Zn), copper (Cu), iron (Fe), calcium (Ca), and magnesium (Mg) concentration in serum, liver, and kidney tissues, and urine samples from adult Wistar rats treated neonatally with streptozotocin (STZ). Diabetes was induced by subcutaneous administration of streptozotocin (100 mg/Kg) in female Wistar rats of 2 days old (STZ, n = 10). Control group (CG, n = 10) received only sodium-citrate buffer.