TiO2 Nanoparticles and Commensal Bacteria Alter Mucus Layer Thickness and Composition in a Gastrointestinal Tract Model

Nanoparticles (NPs) are used in food packaging and processing and have become an integral part of many commonly ingested products. There are few studies that have focused on the interaction between ingested NPs, gut function, the mucus layer, and the gut microbiota. In this work, an in vitro model of gastrointestinal (GI) tract is used to determine whether, and how, the mucus layer is affected by the presence of Gram‐positive, commensal Lactobacillus rhamnosus; Gram‐negative, opportunistic Escherichia coli; and/or exposure to physiologically relevant doses of pristine or digested TiO₂ NPs. Caco‐2/HT29‐MTX‐E12 cell monolayers are exposed to physiological concentrations of bacteria (expressing fluorescent proteins) and/or TiO₂ nanoparticles for a period of 4 h. To determine mucus thickness and composition, cell monolayers are stained with alcian blue, periodic acid schiff, or an Alexa Fluor 488 conjugate of wheat germ agglutinin. It is found that the presence of both bacteria and nanoparticles alter the thickness and composition of the mucus layer. Changes in the distribution or pattern of mucins can be indicative of pathological conditions, and this model provides a platform for understanding how bacteria and/or NPs may interact with and alter the mucus layer.     

Neuromodulation of Astrocytic K+ Clearance

Potassium homeostasis is fundamental for brain function. Therefore, effective removal of excessive K+ from the synaptic cleft during neuronal activity is paramount. Astrocytes play a key role in K+ clearance from the extracellular milieu using various mechanisms, including uptake via Kir channels and the Na⁺-K⁺ ATPase, and spatial buffering through the astrocytic gap-junction coupled network. Recently we showed that alterations in the concentrations of extracellular potassium ([K⁺]_o) or impairments of the astrocytic clearance mechanism affect the resonance and oscillatory behavior of both the individual and networks of neurons. These results indicate that astrocytes have the potential to modulate neuronal network activity, however, the cellular effectors that may affect the astrocytic K+ clearance process are still unknown. In this study, we have investigated the impact of neuromodulators, which are known to mediate changes in network oscillatory behavior, on the astrocytic clearance process. Our results suggest that while some neuromodulators (5-HT; NA) might affect astrocytic spatial buffering via gap-junctions, others (DA; Histamine) primarily affect the uptake mechanism via Kir channels. These results suggest that neuromodulators can affect network oscillatory activity through parallel activation of both neurons and astrocytes, establishing a synergistic mechanism to maximize the synchronous network activity.     

A study of the phosphorescence mechanism of polycrystalline diamond films

A study of the phosphorescence mechanisms in polycrystalline diamond films was carried out through their thermoluminescent (TL) vanishing glow response. The polycrystalline diamond films phosphoresced when kept at room or higher temperatures after being excited with a UV light source. The observed behaviour of shallow and deep traps during the phosphorescence process can be explained with a simple time-dependent model. The diamond film phosphorescence was induced by exciting with a UV light source of 4 W and 254 nm wavelength. The TL vanishing glow curves were integrated from room temperature to 350°C at a linear heating rate of 10°C s^-1 in a N₂ atmosphere. The optical response of the diamond films was studied by means of its luminescence spectra, showing a broad emission band centered around 500 nm.     

Granulomatous amebic encephalitis due to Balamuthia mandrillaris (Leptomyxiidae): report of four cases from Mexico

OBJECTIVE: The influence of psychogenic factors on voiding generally manifests as an irritative syndrome and rarely in the form of acute or chronic urinary retention. The diagnosis and treatment of this uncommon urological pathology are reviewed and our experience is presented. METHODS: We conducted a retrospective study on 5 patients with psychogenic urinary retention (3 males and 2 females), aged 20 to 28 years (mean age 23.4), that had been treated at our urological services over the last 6 years. Three patients (2 males and 1 female) had a history of depression, one patient had a somatic form of disorder (mimicking) and one patient was diagnosed as having schizophrenia one year after he had presented with urinary retention. The physical and neurological examinations were normal in all 5 patients and the radiological evaluation was normal in all but one patient who had bilateral hydronephrosis. The pressure/flow test disclosed absence of detrusor muscle contraction in all 5 patients; 3 had incomplete voiding by abdominal pressure and had more than 500 ml residual urine. All patients received psychiatric therapy, and intermittent catheterization and urinary rehabilitation until residual urine less than 100 ml was achieved. CONCLUSIONS: The importance of the urodynamic study in the diagnosis of this condition is underscored. Definitive diagnosis can only be established after discarding other pathologies. The initial treatment must always be conservative; irreversible surgical procedures must not be performed. Treatment is by intermittent catheterization, urinary rehabilitation and supportive psychiatric therapy.     

Nanostructure development in polystyrene‐b‐polybutadiene‐b‐poly(methyl methacrylate) (SBM) thin films by atomic force microscopy: Effect of copolymer composition and solvent

Surface morphology development for SBM triblock copolymer thin films has been studied by atomic force microscopy. The effect of copolymer composition and solvent on the final morphology has been investigated. Obtained results indicated that depending on the block ratio (symmetric or asymmetric with minority middle block) and solvent, lamellar, hexagonal, cylindrical, or spheres in lamellae (ls)‐type morphologies can be achieved at film surfaces. The influence of the interaction parameters among blocks and solvents and cohesive energy values of block pairs on the final morphology has been proved. POLYM. ENG. SCI., 58:422–429, 2018. © 2017 Society of Plastics Engineers     

Illumination-induced surface charges on thin diamond films at different wavelengths

Contact angle studies of pure water droplets were carried out on thin diamond films. The films were deposited on a fresh Si 111 wafer by plasma assisted chemical vapour deposition (PACVD) and confirmed to be diamond by Raman spectroscopy and scanning electron microscopy. Advancing and receding contact angles were measured as a function of droplet volume by using different incident wavelengths: red, green and violet. Large differences in the contact angles were observed, depending on the wavelength of the incident light. These differences are usually related to the existence of illumination-induced surface charges or electromagnetically active inhomogeneities in the diamond films. The results show that this technique is sufficiently sensitive to correlate changes in the contact angle with changes in the wavelength used.