Controlled Covalent Functionalization of Multiwalled Carbon Nanotubes using [4 + 2] Cycloaddition of Benzocyclobutenes

Surface modification of carbon nanotubes (CNTs) through covalent functionalization is vital for the development of high-performance composite materials, chemosensors, nanoelectronics, photovoltaic devices, as well as for a range of biomedical applications. Several methods have been developed to functionalize CNTs. The introduction of acid groups by acid digestion disrupts the structural integrity of CNTs. Apart from shortening the tubes, oxidatively generated acid groups are inhomogenously located at the tips of broken CNTs and, hence, functionalization using acid groups as precursors does not give a statistical distribution of functional groups throughout the surface of the CNTs.

Morphology and Deformation Mechanisms and Tensile Properties of Tetrafunctional Multigraft Copolymers

Morphology and deformation mechanisms and tensile properties of tetrafunctional multigraft (MG) polystrene-g-polyisoprene (PS-g-PI) copolymers were investigated dependent on PS volume fraction and number of branch points. The combination of various methods such as TEM, real time synchrotron SAXS, rheo-optical FTIR, and tensile tests provides comprehensive information at different dimension levels.TEMand SAXS studies revealed that the number of branch points has no obvious influence on the microphase-separated morphology of tetrafunction MG copolymers with 16 wt % PS. But for tetrafunctional MG copolymers with 25 wt % PS, the size and integrity of PS microdomains decrease with increasing number of branch point. The deformation mechanisms ofMGcopolymers are highly related to the morphology. Dependent on the microphase-separated morphology and integrity of the PS phase, the strain-induced orientation of the PS phase is at different size scales. Polarized FT-IR spectra analysis reveals that, for all investigated MG copolymers, the PI phase shows strain-induced orientation along SD at molecular scale. The proportion of the PI block effectively bridging PS domains controls the tensile properties of the MGcopolymers at high strain, while the stress-strain behavior in the low-mediate strain region is controlled by the continuity of PS microdomains. The special molecular architecture, which leads to the higher effective functionality of PS domains and the higher possibility for an individual PI backbone being tethered with a large number of PS domains, is proposed to be the origin of the superelasticity for MG copolymers.

A Pilot Study to Determine the Effectiveness of Probiotic Use in Elderly Patients with Antibiotic-Associated Diarrhea

Long-term care settings have the majority of their patients on multiple antibiotics, and outbreaks of antibiotic-associated diarrhea and Clostridium difficile are common. Probiotics have been used with these patients to reduce these side effects. Probiotics can re-establish the composition of intestinal microflora, enhance immune response, and clear pathogens from the host which may reduce the symptoms of antibiotic-associated diarrhea. Therefore, the goal of this study was to conduct a retrospective study of the effectiveness of using probiotic in elderly patients in a long-term care facility in a Midwestern city who suffered from antibiotic-associated diarrhea. The probiotic, CulturelleTM had been administered once a day to eight males and twelve female patients who were taking antibiotics and stool consistency and number were recorded. Out of the original group, seven of the patients receiving the probiotic appeared to have positive effects while two patients had negative effects on stools. Thirteen patients showed no change in stool consistency and number. It was difficult to determine the effects of the probiotic due to the use by the facility of a bowel movement protocol for preventing constipation and impaction, and the lack of dietary records. Published studies in patients in long-term facilities vary greatly in terms of trial design, type and dose of probiotic and duration of treatment, which may explain why probiotics work for some patients and not for others. Probiotic use is becoming more accepted with antibiotic-associated diarrhea but due to the lack of definitive evidence about efficacy and the safety of probiotic use, more studies need to be conducted. Advisors: Kaye Stanek Krogstrand and Julie Albrecht

Intestinal permeability parameters in obese patients are correlated with metabolic syndrome risk factors

Background & aims: Altered intestinal permeability has been shown to be associated with metabolic alterations in animal models of obesity, but not in humans. The aim of this study was to assess intestinal permeability in obese women and verify if there is any association with anthropometric measurements, body composition or biochemical variables. Methods: Twenty lean and twenty obese females participated in the study. Anthropometric measurements, body composition and blood pressure were assessed and biochemical analyses were performed. Administration of lactulose and mannitol followed by their quantification in urine was used to assess the intestinal permeability of volunteers. Results: The obese group showed lower HDL (p < 0.05), higher fasting glucose, insulin, HOMA index and lactulose excretion than the lean group (p < 0.05), suggesting increased paracellular permeability. Lactulose excretion showed positive correlation (p < 0.05) with waist and abdominal circumference. Blood insulin and the HOMA index also increased with the increase in mannitol and lactulose excretion and in the L/M ratio (p < 0.05). L/M ratio presented a negative correlation with HDL concentration (p < 0.05). Conclusions: We demonstrated that intestinal permeability parameters in obese women are positively correlated with anthropometric measurements and metabolic variables. Therapeutic interventions focused on intestine health and the modulation of intestinal permeability should be explored in the context of obesity. (C) 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

A novel protein refolding protocol for the solubilization and purification of recombinant peptidoglycan-associated lipoprotein from Xylella fastidiosa overexpressed in Escherichia coil

Xylella fastidiosa is a Gram-negative xylem-limited plant pathogenic bacterium responsible for several economically important crop diseases. Here, we present a novel and efficient protein refolding protocol for the solubilization and purification of recombinant X. fastidiosa peptidoglycan-associated lipoprotein (XfPal). Pal is an outer membrane protein that plays important roles in maintaining the integrity of the cell envelope and in bacterial pathogenicity. Because Pal has a highly hydrophobic N-terminal domain, the heterologous expression studies necessary for structural and functional protein characterization are laborious once the recombinant protein is present in inclusion bodies. Our protocol based on the denaturation of the XfPal-enriched inclusion bodies with 8 M urea followed by buffer-exchange steps via dialysis proved effective for the solubilization and subsequent purification of XfPal, allowing us to obtain a large amount of relatively pure and folded protein. In addition, XfPal was biochemically and functionally characterized. The method for purification reported herein is valuable for further research on the three-dimensional structure and function of Pal and other outer membrane proteins and can contribute to a better understanding of the role of these proteins in bacterial pathogenicity, especially with regard to the plant pathogen X. fastidiosa. (C) 2012 Elsevier Inc. All rights reserved.

Characterization of cuticular hydrocarbons of diploid and haploid males, workers and queens of the stingless bee Melipona quadrifasciata

Males, queens and workers of stingless bees show differences in external morphology, behaviour and roles within a colony. In addition, each individual has a cuticular chemical signature responsible for mutual communication that is essential for maintaining the integrity of the colony. In this paper we characterize the cuticular hydrocarbon composition of newly emerged diploid and haploid males, workers and virgin queens of Melipona quadrifasciata by gas chromatography-mass spectrometry (GC/MS) analysis. This is the first time that the cuticular profile of diploid males in a species of stingless bee has been characterized. We found differences in the cuticular hydrocarbon composition among males, workers and virgin queens, recording both qualitative and quantitative differences among individuals of different phenotypes. However, no compound was found exclusively in diploid males. The cuticular chemical profiles of haploid and diploid males were very similar to those of workers. Moreover, the cuticular lipids of males and workers were significantly different from those of queens. Tricosane, pentacosene-2 and 7-methyl-heptacosane were the compounds responsible for this significant separation. This result correlates with the behavioural and morphological differences among these phenotypes.

Differential expression of toll-like receptor mRNAs in recurrent aphthous ulceration

BACKGROUND: Toll-like receptors (TLR) are membrane proteins that recognize conserved molecules derived from bacterial, viral, fungal or host tissues. They are responsible for promoting the production of cytokines and chemokines, increasing the expression of costimulatory molecules and influencing the T Helper response (Th) toward either a Th1 or Th2 profile, thereby modulating the regulatory T cell response and controlling the integrity of the epithelial barrier. The key factors responsible for increased susceptibility to recurrent aphthous ulceration (RAU) are unclear, and because TLRs are involved in both immune regulation and control of the epithelial barrier, a deficiency in TLR activity is likely to cause increased susceptibility. METHODS: We investigated the gene expression of TLRs one through 10 in tissue samples and peripheral blood mononuclear cells (PBMC) of RAU patients in comparison to healthy controls using real-time quantitative reverse transcription PCR. RESULTS: The analysis of mRNA expression levels in oral lesion showed significant (P < 0.01) overexpression of the TLR2(similar to 6-fold) gene and decreased expression of the TLR3 (similar to 5-fold) and TLR5 (similar to 6-fold) genes in comparison with healthy oral mucosa. The analysis of mRNA expression in PBMC indicated a down-regulation of TLR5 gene expression in the cells from RAU patients (P < 0.05; similar to 2-fold). CONCLUSION: Our results support the hypothesis that a subset of RAU patients has fewer TLR expression that have been tentatively implicated in antiinflammatory effects. This derangement of TLR gene expression may cause an overlay exuberant inflammation reaction in situations where normal individuals are resistant. J Oral Pathol Med (2012) 41: 8085

Long-term effects of oil pollution in mangrove forests (Baixada Santista, Southeast Brazil) detected using a GIS-based multitemporal analysis of aerial photographs

Oil spills are potential threats to the integrity of highly productive coastal wetlands, such as mangrove forests. In October 1983, a mangrove area of nearly 300 ha located on the southeastern coast of Brazil was impacted by a 3.5 million liter crude oil spill released by a broken pipeline. In order to assess the long-term effects of oil pollution on mangrove vegetation, we carried out a GIS-based multitemporal analysis of aerial photographs of the years 1962, 1994, 2000 and 2003. Photointerpretation, visual classification, class quantification, ground-truth and vegetation structure data were combined to evaluate the oil impact. Before the spill, the mangroves exhibited a homogeneous canopy and well-developed stands. More than ten years after the spill, the mangrove vegetation exhibited three distinct zones reflecting the long-term effects of the oil pollution. The most impacted zone (10.5 ha) presented dead trees, exposed substrate and recovering stands with reduced structural development. We suggest that the distinct impact and recovery zones reflect the spatial variability of oil removal rates in the mangrove forest. This study identifies the multitemporal analysis of aerial photographs as a useful tool for assessing a system's capacity for recovery and monitoring the long-term residual effects of pollutants on vegetation dynamics, thus giving support to mangrove forest management and conservation.

Influence of different shrinking temperatures and vacuum conditions on the ability of psychrotrophic Clostridium to cause 'blown pack' spoilage in chilled vacuum-packaged beef

This study determined the ability of psychrotrophic Clostridium strains isolated from vacuum-packaged beefs and abattoir environments to cause 'blown-pack' spoilage of vacuum-packaged beef stored at 2 and 15 degrees C. The influence of shrinking temperatures (83, 84 and 87 degrees C) and vacuum pressure (6 and 9 mbar) on the occurrence of such spoilage as well as the effects of simulated transportation (500 km) on the integrity of packages was determined. At 15 degrees C and 2 degrees C, twelve and six strains caused 'blown-pack' spoilage, respectively. The combination of vacuum pressure (9 mbar) combined with shrinking temperature (87 degrees C) retarded the occurrence of spoilage. The simulated transportation under the experimental conditions did not affect the integrity of packages. More studies that assess the factors that may contribute for the occurrence of 'blown-pack' spoilage should be performed to avoid the occurrence of such spoilage during its shelf-life. (C) 2012 Elsevier Ltd. All rights reserved.

Cytogenetic instability of dental pulp stem cell lines

Human adult stem cells (hASCs) offer a potentially renewable source of cell types that are easily isolated and rapidly expanded for use in regenerative medicine and cell therapies without the complicating ethical problems that are associated with embryonic stem cells. However, the eventual therapeutic use of hASCs requires that these cells and their derivatives maintain their genomic stability. There is currently a lack of systematic studies that are aimed at characterising aberrant chromosomal changes in cultured ASCs over time. However, the presence of mosaicism and accumulation of karyotypic abnormalities within cultured cell subpopulations have been reported. To investigate cytogenetic integrity of cultured human dental stem cell (hDSC) lines, we analysed four expanded hDSC cultures using classical G banding and fluorescent in situ hybridisation (FISH) with X chromosome specific probe. Our preliminary results revealed that about 70% of the cells exhibited karyotypic abnormalities including polyploidy, aneuploidy and ring chromosomes. The heterogeneous spectrum of abnormalities indicates a high frequency of chromosomal mutations that continuously arise upon extended culture. These findings emphasise the need for the careful analysis of the cytogenetic stability of cultured hDSCs before they can be used in clinical therapies.

An evaluation of dosimetric characteristics of MAGIC gel modified by adding formaldehyde (MAGIC-f)

Purpose: To evaluate the dosimetric characteristics of a new formulation of MAGIC gel, called MAGIC-f, which contains the addition of 3.3% formaldehyde, resulting in a gel with increased thermal stability. Methods: MAGIC-f gel was prepared and stored in hermetically sealed plastic containers. After irradiation, magnetic resonance images (MRI) were acquired to evaluate dose and dose distribution. Dosimetric characterization was performed by means of depth dose measurements, dose response sensitivity and linearity, temporal stability, energy and dose rate dependence, dose integration using sequential beams, temperature influence during MRI acquisition and dose distribution integrity. Results: MAGIC-f depth dose measurements are compatible with the dosimetric table data within +/- 4% uncertainty. The dosimeter's R-2 response varies linearly with dose at least from 0 to 6 Gy. The time-course of the sensitivity of the dosimeter following irradiation, indicated stabilization after 2 weeks. The dosimeter's response to irradiation was altered by 6% when increasing the energy from cobalt beams to 10 MV beams. The dose rate dependence of this new formulation of gel dosimeter is small: less than 2.5% for a variation from 200 to 500 cGy/min, and the dependence with the fractionation scheme is about 50% smaller than for standard MAGIC gel, The dependence on scanning temperature was also verified, and the integrity of the dose distribution was confirmed for a period of 90 days. Conclusions: The results demonstrate the applicability of this new dosimeter in tridimensional dose distribution measurements. (C) 2012 Elsevier Ltd. All rights reserved.

Translocation capture sequencing: A method for high throughput mapping of chromosomal rearrangements

Chromosomal translocations require formation and joining of DNA double strand breaks (DSBs). These events disrupt the integrity of the genome and are involved in producing leukemias, lymphomas and sarcomas. Translocations are frequent, clonal and recurrent in mature B cell lymphomas, which bear a particularly high DNA damage burden by virtue of activation-induced cytidine deaminase (AID) expression. Despite the ubiquity of genomic rearrangements, the forces that underlie their genesis are not well understood. Here, we provide a detailed description of a new method for studying these events, translocation capture sequencing (TC-Seq). TC-Seq provides the means to document chromosomal rearrangements genome-wide in primary cells, and to discover recombination hotspots. Demonstrating its effectiveness, we successfully estimate the frequency of c-myc/IgH translocations in primary B cells, and identify hotspots of AID-mediated recombination. Furthermore. TC-Seq can be adapted to generate genome-wide rearrangement maps in any cell type and under any condition. (C) 2011 Elsevier B.V. All rights reserved.

Obstructive acute abdomen due to intestinal intussusception in adolescent

Introduction: Intestinal intussusception is a rare disease out of childhood. It is represented by an invagination of a bowel into the lumen of the adjacent segment. Case Report: This article reports a case of 14 year-old patient presenting intestinal obstruction caused by an intussusception at the level of the terminal ileum. A surgical resection of the invaginated segment was done and the histopathological study disclosed no evidence of malignancy. Discussion: In children, it is usually idiopathic, but among adolescents and adults it is often related to anatomic lesions, some of them neoplastic with high risk of malignancy. Preoperative diagnosis of intestinal intussusception is difficult due to its nonspecific and subacute symptoms. Computed tomography and ultrassonography can confirm the intussusception through characteristic images. Conclusion: Intestinal intussusception in adolescents is a rare and often misdiagnosed disease, deserving special attention from surgeons and general doctors.

Constipation Is More Frequent Than Diarrhea in Patients Fed Exclusively by Enteral Nutrition: Results of an Observational Study

Background: Digestive complications in enteral nutrition (EN) can negatively affect the nutrition clinical outcome of hospitalized patients. Diarrhea and constipation are intestinal motility disorders associated with pharmacotherapy, hydration, nutrition status, and age. The aim of this study was to analyze the frequency of these intestinal motility disorders in patients receiving EN and assess risk factors associated with diarrhea and constipation in hospitalized patients receiving exclusive EN therapy in a general hospital. Materials and Methods: The authors performed a sequential and observational study of 110 hospitalized adult patients fed exclusively by EN through a feeding tube. Patients were categorized according to the type of intestinal transit disorder as follows: group D (diarrhea, 3 or more watery evacuations in 24 hours), group C (constipation, less than 1 evacuation during 3 days), and group N (absence of diarrhea or constipation). All prescription drugs were recorded, and patients were analyzed according to the type and amount of medication received. The authors also investigated the presence of fiber in the enteral formula. Results: Patients classified in group C represented 70% of the study population; group D comprised 13%, and group N represented 17%. There was an association between group C and orotracheal intubation as the indication for EN (P<.001). Enteral formula without fiber was associated with constipation (logistic regression analysis: P<.001). Conclusion: Constipation is more frequent than diarrhea in patients fed exclusively by EN. Enteral diet with fiber may protect against medication-associated intestinal motility disorders. The addition of prokinetic drugs seems to be useful in preventing constipation. (Nutr Clin Pract. XXXX;xx:xx-xx)

Effect of dental tissue conditioners and matrix metalloproteinase inhibitors on type I collagen microstructure analyzed by Fourier transform infrared spectroscopy

This study aimed to evaluate the chemical interaction of collagen with some substances usually applied in dental treatments to increase the durability of adhesive restorations to dentin. Initially, the similarity between human dentin collagen and type I collagen obtained from commercial bovine membranes of Achilles deep tendon was compared by the Attenuated Total Reflectance technique of Fourier Transform Infrared (ATR-FTIR) spectroscopy. Finally, the effects of application of 35% phosphoric acid, 0.1M ethylenediaminetetraacetic acid (EDTA), 2% chlorhexidine, and 6.5% proanthocyanidin solution on microstructure of collagen and in the integrity of its triple helix were also evaluated by ATR-FTIR. It was observed that the commercial type I collagen can be used as an efficient substitute for demineralized human dentin in studies that use spectroscopy analysis. The 35% phosphoric acid significantly altered the organic content of amides, proline and hydroxyproline of type I collagen. The surface treatment with 0.1M EDTA, 2% chlorhexidine, or 6.5% proanthocyanidin did not promote deleterious structural changes to the collagen triple helix. The application of 6.5% proanthocyanidin on collagen promoted hydrogen bond formation. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.