Biomimetic graphene for enhanced interaction with the external membrane of astrocytes.

Graphene and graphene substrates display huge potential as material interfaces for devices and biomedical tools targeting the modulation or recovery of brain functionality. However, to be considered reliable neural interfaces, graphene-derived substrates should properly interact with astrocytes, favoring their growth and avoiding adverse gliotic reactions. Indeed, astrocytes are the most abundant cells in the human brain and they have a crucial physiological role to maintain its homeostasis and modulate synaptic transmission. In this work, we describe a new strategy based on the chemical modification of graphene oxide (GO) with a synthetic phospholipid (PL) to improve interaction of GO with brain astroglial cells. The PL moieties were grafted on GO sheets through polymeric brushes obtained by atom-transfer radical-polymerization (ATRP) between acryloyl-modified PL and GO nanosheets modified with a bromide initiator. The adhesion of primary rat cortical astrocytes on GO-PL substrates increased by about three times with respect to that on glass substrates coated with standard adhesion agents (i.e. poly-d-lysine, PDL) as well as with respect to that on non-functionalized GO. Moreover, we show that astrocytes seeded on GO-PL did not display significant gliotic reactivity, indicating that the material interface did not cause a detrimental inflammatory reaction when interacting with astroglial cells. Our results indicate that the reported biomimetic approach could be applied to neural prosthesis to improve cell colonization and avoid glial scar formation in brain implants. Additionally, improved adhesion could be extremely relevant in devices targeting neural cell sensing/modulation of physiological activity.

Interaction of graphene-related materials with human intestinal cells: an in vitro approach.

Graphene-related materials (GRM) inherit unique combinations of physicochemical properties which offer a high potential for technological as well as biomedical applications. It is not clear which physicochemical properties are the most relevant factors influencing the behavior of GRM in complex biological environments. In this study we have focused on the interaction of GRM, especially graphene oxide (GO), and Caco-2 cells in vitro. We mimiked stomach transition by acid-treatment of two representative GRM followed by analysis of their physicochemical properties. No significant changes in the material properties or cell viability of exposed Caco-2 cells in respect to untreated GRM could be detected. Furthermore, we explored the interaction of four different GO and Caco-2 cells to identify relevant physicochemical properties for the establishment of a material property-biological response relationship. Despite close interaction with the cell surface and the formation of reactive oxygen species (ROS), no acute toxicity was found for any of the applied GO (concentration range 0-80 µg ml(-1)) after 24 h and 48 h exposure. Graphene nanoplatelet aggregates led to low acute toxicity at high concentrations, indicating that aggregation, the number of layers or the C/O ratio have a more pronounced effect on the cell viability than the lateral size alone.

Flake size-dependent cyto and genotoxic evaluation of graphene oxide on in vitro A549, CaCo2 and vero cell lines.

This study was carried out by varying both graphene oxide (GO) concentration (10 μg/mL, 50 μg/mL, 100 μg/mL) and flakes sizes of 1320 nm and 130 nm. Characterization by scanning electron microscopy and Raman spectroscopy demonstrate that the area of GO flakes varies of one order of magnitude but their chemical structure remains unmodified. A 24-h cytotoxicity test showed, for A549, a loss in the viability, while the test exhibits overall a positive increase in the viability for CaCo2 and Vero. A 24-h comet assay shows a marked GO genotoxicity: for micrometer-sized GO flakes the genotoxicity is in positive correlation with the concentration, while for nanometer-sized GO flakes there was a high degree of genotoxicity at the lowest concentration tested.

Assessment of mitral regurgitation severity by Doppler color flow mapping of the vena contracta in dogs.

BACKGROUND: Quantitative and semiquantitative methods have been proposed for the assessment of MR severity, and though all are associated with limitations. Measurement of vena contracta width (VCW) has been used in clinical practice. OBJECTIVE: To measure the VCW in dogs with different levels of MR severity. ANIMALS: Two hundred and seventy-nine dogs were classified according to 5 levels of MR severity. METHODS: This was a retrospective study. EROA and regurgitant volume calculated by the PISA method, were measured and indexed to BSA. Descriptive statistics were calculated for VCW and VCW index for all categories of MR severity. Spearman's rank correlation coefficients (ρs ) were calculated to compare the results of the different methods (VCW and VCW index vs RV PISA, RV PISA index, EROA, EROA index), and between VCW and VCW index versus MR severity. RESULTS: All Spearman's rank correlation coefficients were significant (P < .001). The median values of VCW resulted of 2.9 mm (IQR 3.4-2.5) and of 4.6 mm (IQR 5.4-4.1) in the groups previously classified as mild-to-moderate and moderate-to-severe, respectively. The median values of VCW index resulted of 4.4 mm/m(2) (IQR = 5.5-4.2) in mild-to-moderate MR and of 10.8 mm/m(2) (IQR = 12.8-9.4) in moderate-to-severe MR. CONCLUSION AND CLINICAL IMPORTANCE: This is not a validation study against any previously validated invasive gold standard, the VCW method has proved easy to employ and it might be an additional tool in quantifying disease severity that supports, rather than replace, data coming from other techniques in daily clinical practice and research.

Prognostic value of 24-hour ambulatory ECG (Holter) monitoring in Boxer dogs.

BACKGROUND: Boxer dogs are reported to be predisposed to arrhythmogenic right ventricular cardiomyopathy (ARVC), but the natural history has not been well characterized and inconsistent diagnostic criteria have been applied to identify affected dogs. Echocardiographic examination findings are unremarkable in many affected Boxer dogs, and in these dogs, 24-hour ambulatory ECG (Holter) monitoring often is used for diagnostic and prognostic purposes, despite limited information available relating Holter findings to outcome. HYPOTHESIS/OBJECTIVES: Boxers with complex ventricular arrhythmias at initial presentation will have shorter survival times. The objective was to investigate the prognostic value of Holter monitoring in Boxer dogs. ANIMALS: One hundred and twenty-two Boxer dogs seen at 3 university referral hospitals. METHODS: Retrospective study. Survival times were obtained for Boxer dogs evaluated by echocardiography and a 24-hour Holter ECG. Kaplan-Meier survival analysis was used to estimate the median survival time and Cox proportional hazards analysis was used to identify variables independently associated with cardiac mortality. RESULTS: Outcome data were obtained for 122/163 dogs meeting the inclusion criteria. Of the 70 dogs that had died, 45 were considered to have suffered cardiac-related deaths. Median survival was significantly longer in dogs with a left ventricular systolic diameter (LVIDs) ≤ 35 mm compared with those with LVIDs > 35 mm (P < .001). Multivariable analysis in dogs with LVIDs ≤ 35 mm showed that the presence of ventricular tachycardia, age >4.5 years, and male sex were independent predictors of cardiac mortality. CONCLUSIONS AND CLINICAL IMPORTANCE: Holter monitoring in Boxer dogs provides valuable prognostic information.

Large area extreme-UV lithography of graphene oxide via spatially resolved photoreduction.

The ability to pattern graphene over large areas with nanometer resolution is the current request for nanodevice fabrication at the industrial scale. Existing methods do not match high throughput with nanometer resolution. We propose a high-throughput resistless extreme-UV (EUV) photolithographic approach operating with sub-micrometer resolution on large area (~10 mm(2)) graphene oxide (GO) films via spatially resolved photoreduction. The efficiency of EUV photoreduction is tested with 46.9 nm coherent light produced by a table top capillary discharge plasma source. Irradiated samples are studied by X-ray photoemission spectroscopy (XPS) and micro-Raman Spectroscopy (µRS). XPS data show that 200 mJ/cm(2) EUV dose produces, onto pristine GO, a 6% increase of sp(2) carbon bonds and a 20% decrease of C-O bonds. µRS data demonstrate a photoreduction efficiency 2 orders of magnitude higher than the one reported in the literature for UV-assisted photoreduction. GO patterning is obtained modulating the EUV dose with a Lloyd's interferometer. The lithographic features consist of GO stripes with modulated reduction degree. Such modulation is investigated and demonstrated by µRS on patterns with 2 µm periodicity.

Photoinduced work function changes by isomerization of a densely packed azobenzene-based SAM on Au: a joint experimental and theoretical study.

Responsive monolayers are key building blocks for future applications in organic and molecular electronics in particular because they hold potential for tuning the physico-chemical properties of interfaces, including their energetics. Here we study a photochromic SAM based on a conjugated azobenzene derivative and its influence on the gold work function (Φ(Au)) when chemisorbed on its surface. In particular we show that the Φ(Au) can be modulated with external stimuli by controlling the azobenzene trans/cis isomerization process. This phenomenon is characterized experimentally by four different techniques, kelvin probe, kelvin probe force microscopy, electroabsorption spectroscopy and ultraviolet photoelectron spectroscopy. The use of different techniques implies exposing the SAM to different measurement conditions and different preparation methods, which, remarkably, do not alter the observed work function change (Φ(trans)-Φ(cis)). Theoretical calculations provided a complementary insight crucial to attain a deeper knowledge on the origin of the work function photo-modulation.

Echocardiographic values in clinically healthy adult dogue de Bordeaux dogs.

OBJECTIVES: To assess the influence of body surface area, age and gender on echocardiographic parameters and to establish echocardiographic reference values for dogue de Bordeaux dogs. METHODS: Thirty-nine healthy dogue de Bordeaux dogs of both sexes, older than one year, were recruited and 31 of these were included in the study. The classic linear regression model proved to be the best way to analyse the data. The reference limits of the echocardiographic measurements were calculated using the regression equations. The difference between the mean values of body surface area in both gender groups was evaluated by using one-way ANOVA. RESULTS: A significant correlation was seen between several echocardiographic parameters and body surface area or body surface area and age, and high coefficients of determination (R2) were found. No effect of gender was detected on echocardiographic variables, except for the thickness of the left ventricular posterior wall at end diastole. CLINICAL SIGNIFICANCE: The echocardiographic parameters related to body surface area, in the absence of correlation with other independent variables (gender and age) should be interpreted with caution because their variation could be significant for the presence of heart disease. The proposed statistical model allows estimation of echocardiographic parameters in dogue de Bordeaux dogs with different body surface areas and ages.

Micron-sized [6,6]-phenyl C61 butyric acid methyl ester crystals grown by dip coating in solvent vapour atmosphere: interfaces for organic photovoltaics.

We have devised a novel dip coating procedure to form highly crystalline and macroscopic pi-conjugated architectures on solid surfaces. We have employed this approach to a technologically relevant system, i.e. the electron-acceptor [6,6]-phenyl C61 butyric acid methyl ester molecule (PCBM), which is the most commonly used electron-acceptor in organic photovoltaics. Highly ordered, hexagonal shaped crystals of PCBM, ranging between 1 to 80 mum in diameter and from 20 to 500 nm in thickness, have been grown by dip coating the substrates into a solution containing the fullerene derivative. These crystals have been found to possess a monocrystalline character, to exhibit a hexagonal symmetry and to display micron sized molecularly flat terraces. The crystals have been prepared on a wide variety of surfaces such as SiO(x), silanized SiO(x), Au, graphite, amorphous carbon-copper grids and ITO. Their multiscale characterization has been performed by atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), X-ray diffraction (XRD), optical microscopy, scanning and transmission electron microscopy (SEM, TEM).To test the stability of these electron accepting PCBM crystals, they have been coated with a complementary, electron donor hexa-peri-hexabenzocoronene (HBC) derivative by solution processing from acetone and chloroform-methanol blends. The HBC self assembles in a well-defined network of nanofibers on the PCBM substrate, and the two materials can be clearly resolved by AFM and KPFM.Due to its structural precision on the macroscopic scale, the PCBM crystals appear as ideal interface to perform fundamental photophysical studies in electron-acceptor and -donor blends, as well as workbench for unravelling the architecture vs. function relationship in organic solar cells prototypes.

Polycystic ovary syndrome and metabolic comorbidities: therapeutic options.

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women and the most common cause of anovulatory infertility, affecting 5-10% of the population. Approximately 60-70% of PCOS patients are obese. Although it is well known that obesity is associated with insulin resistance, most studies have shown that impaired insulin sensitivity is present without obesity. Hyper-insulinemia associated with insulin resistance has been causally linked to all features of the syndrome, such as hyperandrogenism, reproductive disorders, acne, hirsutism and metabolic disturbances. PCOS patients often have an atherogenic lipid profile and increased incidence of cardiovascular risk factors and type 2 diabetes. It has been demonstrated that by reducing hyper-insulinemia, insulin-lowering agents might improve endocrine and reproductive abnormalities in PCOS patients, and have numerous beneficial effects on multiple cardiovascular risk factors in PCOS. Metformin is currently the preferred insulin-sensitizing drug for chronic treatment of PCOS and has been shown to improve the metabolic profile, menstrual cyclicity and fertility in women with PCOS, and is associated with weight loss. In this review the metabolic comorbidities of PCOS and their therapeutic options are discussed.

Apoptosis and aging in mitochondrial morphology mutants of S. cerevisiae.

Cell viability during chronological aging and after apoptotic stimuli in some yeast mutants with altered mitochondrial morphology was followed; a function for the corresponding genes in the apoptotic process was assessed. MDM30 and DNM1, the genes encoding an F-box protein and the dynamin-related GTPase, respectively, are involved in triggering aging and apoptosis. In contrast, YME1, encoding a subunit of the mitochondrial inner membrane i-AAA proteinase complex, has a protective role in these processes. FIS1, the mitochondrial fission gene, might play a protective role after an apoptotic insult while it seems to promote cell death in aging cells.

Improved endocervical cell yield with Cytobrush.

A prospective study of 402 Papanicolaou smears was done comparing the effectiveness of three techniques in obtaining endocervical cells. The Zelsmyr Cytobrush cell collector yielded the greatest concentration of endocervical cells. More than one half (53.6 percent) of all cell samples obtained with the Zelsmyr Cytobrush produced "moderate" or "large" concentrations. The extended-tip spatula and cotton-tip swab techniques produced only 38.5 percent and 24.2 percent, respectively, in these categories. The Zelsmyr Cytobrush cell collector is an effective instrument, yielding increased numbers of endocervical cells on Papanicolaou smear.

Lethal hyperparathyroid crisis: hazards of phosphate administration.

Two patients with hypercalcemia crisis and parathyroid adenoma died as a result of pulmonary insufficiency. The administration of phosphate is believed to have contributed to the deaths, since the pulmonary problems appeared when the blood [Ca] X [PO4] product rose and extensive metastatic calcification was present in the pulmonary alveolar lining. The use of phosphates as calcium-lowering agents in hypercalcemia is discouraged, because phosphate appears to lower calcium levels only by intravascular precipitation.

Cytologic diagnosis of endometrial adenocarcinoma using the Endo-pap sampler.

Six hundred ambulatory women were screened with the Endo-pap cytology sampler in two medical centers. None of the women developed complications from the use of the instrument. Their smears were routinely processed together with cervical cytology smears. One hundred fifty-three of these women had a tissue diagnosis by endometrial biopsy, dilatation and curettage, or hysterectomy. Adequate cytology specimens were obtained in 93% of these patients. In these 153 patients, 32 (18%) had a tissue diagnosis of endometrial adenocarcinoma, and 31 patients had a tissue diagnosis of endometrial hyperplasia. The cytology samples obtained with this device were diagnostic of endometrial adenocarcinoma in 30 (94%) of these 32 patients and ten (32%) of the patients with endometrial hyperplasia. Two patients (1.6%) were diagnosed falsely positive. The Endo-pap cytology sampler is considered a safe and effective screening tool for endometrial adenocarcinoma. Its value in diagnosing endometrial hyperplasia remains to be determined.

Interpretation of endometrium obtained by the Endo-pap sampler and a clinical study of its use.

Endometrical cytology sampling using the Endo-pap sampler is an inexpensive, painless, and simple procedure. Tissue microfragments obtained include surface epithelial sheets, gland segments, and stromal cell aggregates. Gland segments are critical for evaluation of the sample. Glands are dilated in hyperplasia and there is nuclear crowding with increase of chromatin and nucleoli. In adenocarcinoma there is loss of glands with marked nuclear enlargement and pleomorphism. An understanding of endometrial histomorphology and its correlation with cytology is essential for accurate interpretation. In 1027 ambulatory patients screened, no complications were observed and 92% of the samples were adequate for cytologic diagnosis. Tissue diagnosis was obtained in 173 cases. There were 36 adenocarcinomas, of which 34 (94%) were diagnosed cytologically. There were 16 hyperplasias, of which 5 (31%) were diagnosed cytologically. The Endo-pap sampler was found effective in detecting endometrial adenocarcinoma. Further studies are needed to determine its diagnostic effectiveness in hyperplasia.