Dye Migration Research Articles

Electrochemically Induced pH Change: Time-Resolved Confocal Fluorescence Microscopy Measurements and Comparison with Numerical Model.

Confocal fluorescence microscopy is a proven technique, which can image near-electrode pH changes. For a complete understanding of electrode processes, time-resolved measurements are required, which have not been achieved previously. Here we present the first measurements of time-resolved pH profiles with confocal fluorescence microscopy. The experimental results compare favorably with a one-dimensional reaction–diffusion model; this holds up to the point where the measurements reveal three-dimensionality in the pH distribution. Specific factors affecting the pH measurement such as attenuation of light and the role of dye migration are also discussed in detail. The method is further applied to reveal the buffer effects observed in sulfate-containing electrolytes. The work presented here is paving the way toward the use of confocal fluorescence microscopy in the measurement of 3D time-resolved pH changes in numerous electrochemical settings, for example, in the vicinity of bubbles.

Ultrasonic Effects on the Kinetics and Thermodynamics of Dyeing Wool Fiber with Reactive Dye

Decreasing the temperature for dyeing wool fiber with reactive dye using a laboratory based ultrasonic machine was investigated as a way to obtain good quality dyed samples. Ultrasonic irradiation was used to reduce dyeing time and temperature whilst increasing dye migration and fastness. The ultrasonic machine was set at a 40 kHz frequency level, with effective power of 130 W and heating power of 350 W to carry out the dyeing process of the wool fiber within the temperature range 60-80 °C. The dyeing processes used both ultrasonic dyeing and without ultrasonic dyeing to obtain the laboratory results. At every dyeing stage from 60 °C to 80 °C, the exhaustion rate of dyeing was measured. Ultrasonic dyeing yielded better results compared to without ultrasonic dyeing. The diffusion coefficient, partition ratio, and standard affinity increased with the increased dyeing temperature and the use of an ultrasonic bath. The efficiency of ultrasonic dyeing was measured and the absorption rate constant was at least 55 % greater than without ultrasonic dyeing at every dyeing temperature i.e. 60 °C, 70 °C, and 80 °C. The color fastness to washing and rubbing was better for samples dyed with ultrasonic dyeing. Scanning electron microscopy (SEM) was used to measure the surface changes of the fiber. SEM analysis showed no evidence of scale damage on the wool fiber surface.

Digital Textile Printing: A New Alternative to Short-Run Textile Printing in Ghana

This paper is a part of a broader research into textile design technology and trends across the world and their reflection on the local Ghanaian textile industry. It places conventional manual screen printing and digital textile printing technologies side by side and discusses the various drawbacks of screen printing as against the advantages of digital textile printing to illustrate a path for a wider consideration of the latter in Ghanaian small to medium scale textile production. Short-run textile printing commissions are the main source of jobs for small to medium scale textile producers in Ghana. And manual screen printing is the main process employed by these small-scale textile printers. However, screen printing has various layers of limitations such as poor registration of the design, stains, pinholes, colour correctness, colour consistency, colour smear, dye migration, scorching, improper curing, amongst others. These layers of limitations negatively affect the overall outcome of the prints. So, as it stands now, short-run textile printing commissions are either produced manually, of course, with several inconsistencies or outsourced to China and other countries at a higher production cost. This is because, the large-scale textile factories in Ghana could print a minimum of 2400 yards due to their machine settings, calibration and running cost to make the least returns. This study highlights some of the milestones in the development of digital textiles print machines and examines some of the key aspects of their tremendous production aptitudes for short-run textile commissions. The case study research method is used because data comes largely from documentation, archival records, interviews and physical artefacts.
 Keywords: Textile Design, Digital Textile Printing, Screen Printing, Short-run Prints.

An inkjet‐printed sulfonephthalein dye indicator array for volatile amine detection

Colorimetric indicators are versatile for applications such as intelligent food packaging, for reflecting the actual quality and/or monitoring distribution history of food products. In this study, a colorimetric indicator array composed of sulfonephthalein dyes was successfully developed by piezoelectric inkjet printing, for the detection of volatile amines-the primary spoilage gases for fish and seafood products. The printing inks were formulated in water/ethanol/1-butanol mixture. By refilling the printer's cartridges with our formulated inks and controlling the red, green, and blue color parameters, a 7×9 indicator array was printed onto inkjet transparency films. The color response of the indicator array was tested with different volatile amines at various concentrations. The array indicator was capable of discriminating six different volatile amines: ammonia, trimethylamine, dimethylamine, triethylamine, piperidine, and hydrazine. The printability of the inks was investigated by characterizing their density, surface tension, and dynamic viscosity, dictating that all formulated inks were printable fluid. The microstructural morphologies of the printed dyes on transparency films were evaluated using scanning electron microscopy. Interactions of the dye with the volatiles were studied by Fourier transform infrared spectroscopy. In summary, the piezoelectric inkjet printing method presented in this study offers a convenient, efficient, and flexible means to fabricate colorimetric indicators for detecting food spoilage volatiles. These indicators are promising as sensing components in intelligent packaging systems, to reveal the freshness of fish products by correlating with quality parameters such as total volatile basic nitrogen, microbial growth, and sensory attributes. Further studies on the feasibility of using the array indicators in real food packaging systems, development of strategy to mitigate the potential migration of the indicator dyes, and designing array patterns optimal for machine/human interpretation, are important to commercialize the technology. PRACTICAL APPLICATION: Piezoelectric inkjet printing offers a convenient way to fabricate sensing materials and aligns with industrial packaging operations. The use of indicators on food package helps consumers more accurately perceive real-time food quality information.

Mechanical stretch upregulates connexin43 in human trabecular meshwork cells.

Primary open angle glaucoma (POAG) patients have hallmark increases in intraocular pressure (IOP) and noted dysfunction of the trabecular meshwork (TM). Connexin43 (Cx43) is a gap junction widely expressed on the TM that is important for intercellular communication. The human gene is known as gap junction alpha-1 (GJA1). Since the role of Cx43 in the TM is not fully understood, we set out to determine the effect of excess mechanical stretch on cultured human trabecular meshwork cells (hTMCs) and to specifically investigate the effect of stretch on Cx43 expression and function. Primary hTMCs were cultured and subjected to 48 hours of 15% cyclic mechanical stretch at a frequency of 1 Hz. Levels of apoptosis and necrosis secondary to stretch were investigated using colorimetric assays. The effect of stretch on gap junction Cx43 and GJA1 was investigated by RT-PCR, immunoblotting and immunofluorescence. The migration of Lucifer Yellow dye was used to assess intercellular communication. Stretch significantly increased the rates of apoptosis and necrosis in hTMCs. The increased rate of injury in stretched hTMCs was further associated with significant upregulation of GJA1 mRNA and Cx43 protein. Upregulation of Cx43 protein was concomitant to increased intercellular communication. We have shown stretch to increase GJA1 gene and Cx43 protein expression, as well as intercellular communication. We have further shown stretch to be injurious to hTMCs. Upregulation of Cx43 in the hTM subsequent to stretch is a novel finding, which may be useful in elucidating the mechanism of TM injury in POAG patients.

Skin incision versus laser - the influence of different techniques on scar formation and lymphatic drainage in rats. A preliminary report.

IntroductionThe constantly rising number of skin malignancies and increasing cancer awareness encourage more people to visit outpatient clinics in order to have various skin lesions removed. Despite the fact that scarring is a physiological response to any excision procedure, minimizing the size of it is a goal of every good practitioner. Therefore the question arises whether different techniques used to remove skin lesions may impact the formation and quality of skin scars.AimTo perform an evaluation of skin scars formed by laser and surgical incisions and their influence on lymphatic outflow in rats.Material and methodsFive male rats were used. Using methylene blue, the migration of dye through lymphatic channels of the lower extremity was measured. Afterwards, transverse incisions were made distally using laser and a surgical blade. Wounds were left to heal by secondary intention. After 4 weeks dye migration assessment was repeated and tissue samples were obtained for microscopic evaluation.ResultsWounds after surgical incisions healed entirely. Wounds after laser treatment had not healed, with a visible area of granulation tissue and hair loss. Significantly worse dye migration was observed in rat extremities after laser therapy than after surgical incision (p = 0.007).ConclusionsThe results of the study show that the size of the scar can depend on the incision technique used. Larger scars after laser therapy limit the lymphatic flow of the skin, which may have an adverse effect on mapping sentinel lymph nodes. However, this hypothesis requires further research.

Nanocellulose for gel electrophoresis

HypothesisCellulose nanofibres produced by TEMPO-mediated oxidation can form gels. This study presents a proof-of-concept for gel electrophoresis with nanocellulose (NC). ExperimentsTEMPO-oxidised cellulose nanofibre dispersion is chemically cross-linked by inducing amide linkages to produce gel slabs for electrophoretic separation. Nanocellulose gel slabs 1 cm thick containing Tris/Borate/EDTA (TBE) buffer were casted. Different cross-linker types and ratios are investigated to assess the migration of conventional electrophoresis tracking dyes. FindingsTracking dyes (bromophenol blue and orange G) can diffuse within the gel at different rates and therefore separate. Changing the cross-linker length from EDA to HMDA (C2- to C6-chain) increases the overall network pore size resulting in a faster migration rate for both bromophenol blue and orange G. Increasing the cross-linker concentration stabilises the HMDA-NC gel (no extension) during the electrophoresis run without any effect on the dye migration rate. Increasing the voltage increases the migration rates for both orange G and bromophenol blue. Further development is required to cast the gels evenly and to prevent bubble formation during the cross-linking process. This will enable to effectively separate mixtures of proteins. Nanocellulose gels can become a novel substrate for sustainable biomedical separation and diagnostics by electrophoresis.

The protective effect of endothelin receptor antagonists against surgically induced impairment of gastrointestinal motility in rats.

Endothelin (ET) receptor antagonists: BQ-123 (ETA), BQ-788 (ETB), tezosentan (dual ET receptor antagonist) protect against the development of postoperative ileus (POI) evoked by ischemia-reperfusion (I/R). The current experiments explored whether ET antagonists prevent the occurrence of POI evoked by surgical gut manipulation. Intestinal transit was assessed by measuring the rate of dye migration subsequent to skin incision (SI), laparotomy (L), or laparotomy and surgical gut handling (L+M) in diethyl ether anaesthesized rats (E). Experimental animals were randomly sub-divided into two groups depending on the time of recovery following surgery: viz. either 2 or 24 h (early or late phase POI). E and SI did not affect the gastrointestinal (GI) transit. In contrast, L and L+M significantly reduced GI motility in comparison to untreated group (UN). Tezosentan (10 mg/kg), BQ-123 and BQ-788 (1 mg/kg) protected against development of L+M evoked inhibition of intestinal motility in the course of late phase, but not early phase POI. Furthermore, tezosentan alleviated the decrease in the contractile response of the longitudinal jejunal smooth muscle strips to carbachol in vitro induced by L+M. The serum ET(1–21) concentration was not increased in either the early or the late phase POI groups after surgery compared to control animals. This study indicates that delay in the intestinal transit in late phase of surgically induced POI involves an ET-dependent mechanism.

A freshness indicator for monitoring chicken-breast spoilage using a Tyvek® sheet and RGB color analysis

Abstract In this study, a simple, inexpensive, and high-confidence freshness indicator was developed to detect chicken-breast spoilage using a pH-sensitive dye, bromocresol green (BCG); color changes in the freshness indicator were analyzed using RGB digital images. The indicator consisted of a three-layered structure, using a Tyvek® sheet with high gas and vapor permeability as the inner layer, BCG-immobilized with the binding polymer as the color-changing layer, and a low-density polyethylene film as the outer layer. Color changes in the indicator were correlated with CO2 and total volatile basic nitrogen contents and bacterial growth in the chicken breast, which were quantified using digital images captured on a smartphone. When the indicator turned yellow from green, it indicated spoilage; further, a large difference was observed in the RGB values. The proposed freshness indicator with no dye migration is highly feasible, safe, and reliable for the real-time monitoring of quality changes in chicken breasts. Digital image processing via a smartphone makes it a simple and accurate method, allowing consumers to judge food quality easily and reliably.

Synthesis and application of N-butyl substituted phthalimide disperse dyes

Three azo dyes were synthesized using N-butyl substituted phthalimides as diazo components. All of the synthesized intermediate derivatives and dyes were characterized by mass spectrometry, proton nuclear magnetic resonance, infrared (IR) and elemental analyses. Synthesized dyes were also evaluated for their dyeing behavior and fastness properties toward polyester fabric. The ultraviolet-visible absorption maxima of the dyes were observed in the range of 445–563 nm. Bromo and cyano substitutions at the 3- and/or 5- positions of the phthalimide ring resulted in hypsochromic and bathochromic shifts, respectively. IR spectra peaks at 1770 and 1395 cm−1 of hydrolyzed dye showed that C–O groups appeared under relatively mild alkaline conditions. The K/ S values of dyed polyester/elastane fabrics decreased obviously as the pH value increased. Hydrolysis of the phthalimide ring was found to be largely influenced by steric effects rather than inductive effects. Bromo substituted dyes have the lowest rates of hydrolysis. Compared with S-type dyeing disperse dyes, phthalimide dyes have lower dyeing rates and lower levelness of dye migration. The ωB97XD/6-311G(d,p) calculation found that pi-stacking interactions of phthalimide–benzene and phthalimide–phthalimide dimers increased the dye–fiber and dye–dye interactions.

Black chokeberry (Aronia melanocarpa) pomace extract immobilized in chitosan for colorimetric pH indicator film application

During this study, different amounts of black chokeberry (Aronia Melanocarpa) pomace extract were mixed with chitosan to prepare colorimetric pH indicator films. The monomeric anthocyanin and total phenol content of ultrasonically extracted chokeberry pomace solution were determined by pH differential method and Folin-Ciocaltau assay. ATR-FTIR spectroscopy, CIELab method, solubility, swelling ability, dye migration and tensile strength measurements were used to characterize the films. The pomace extract contained enough active components to highly reduce the solubility and swelling of chitosan. The indicator films maintained their integrity even at acidic pH which was attributed to the interactions between the polymer chains and the phenolic components of the extract. With higher extract content, a higher resistance to water was observed, which also resulted in reduced dye migration. The immobilized dye in chitosan films responded well to the pH change and showed a high color difference from pH 1 to pH 10.

23. Constitutively Active Signal Transducer and Activator of Transcription-3; an Oncogene that Increases Gap Junctional, Intercellular Communication


 Gap junctions are specialized intercellular channels that connect the cytoplasm of adjacent cells and mediate the direct exchange of small ions and molecules between them. Gap junctional intercellular communication (GJIC) is usually blocked, or down regulated, in cells transformed by oncogenes, such as Src. One of the Src effector pathways leading to transformation and GJIC suppression is the Ras/Raf/MEK/ERK pathway that has a prominent etiological role in cell proliferation, differentiation and cell survival; inhibition of this pathway in vSrc transformed cells restores GJIC. In addition, the distinct downstream effector of Src that is obligatory for neoplasia is the signal transducer and activator of transcription-3 (Stat3). Stat3 is up regulated in a range of tumors, and a modified version, the constitutively active form of Stat3 (Stat3C), has been shown to function as an oncogene. To examine the role of Stat3 upon the Src-mediated, GJIC suppression, Stat3 was down regulated in rat liver epithelial T51B cells expressing activated Src. The extent of GJIC was determined by the migration of the fluorescent dye, Lucifer Yellow, through adherent cells subsequent to electroporation. The results demonstrate that, contrary to inhibition of the Ras pathway, Stat3 inhibition in cells expressing activated Src does not restore GJIC. On the contrary, Stat3 inhibition in normal cells with high GJIC levels eliminated junctional permeability. Interestingly, our results also demonstrate that expression of Stat3C T51B cells and human lung cancer SK-LuCi6 cells, which have extensive communication and low Src levels, increased GJIC. Therefore, Stat3 is actually required for and increases junctional permeability.

Effect of ultrasound on dyeing of wool fabric with acid dye

Wool fiber strength and handle is damaged by holding for prolonged periods at normal dyeing temperatures (98 °C). Lower dyeing temperatures can be employed to color wool whilst reducing damage caused to the fiber. However, these lower temperature dyeing processes often have a long dyeing time and/or require the addition of chemicals to achieve adequate dye exhaustion and migration. The use of ultrasonic irradiation was used to reduce dyeing times and temperatures whilst increasing dye migration and fastness. It has used 30 kHz frequency level, effective power of 120 and 350 W heating power in ultrasonic machine. In this work, wool dyeing was carried out on single jersey knitted fabric using an acid dye with and without ultrasonic irradiation at 60, 70, and 80 °C. Dye exhaustion was measured using UV/visible absorbance of the dye bath before and during the dyeing cycle. For the measurement of nodal/anti-nodal point of energy, at 60, 70, and 80 °C dyeing was done in open bath of ultrasonic machine with and without sonication at high liquor ratio. To compare the dye uptake (%) at high/conventional process, sample was dyed at 95 °C. Optical and scanning electron microscopy were used to measure the diameter and surface changes of the fiber, respectively. Wash and rub fastness was measured on the dyed fabrics after rinsing and drying. Ultrasonic irradiation during the dyeing of wool caused an increase in the dye exhaustion rate for acid dye. This change in rate is believed to have been caused by a reduction in the viscous boundary layer of liquor surrounding the fiber present in an ultrasonic irradiated environment. An increased dye migration due to cuticle cracking and fiber swelling was not deemed to have occurred as wet fiber diameter was not changed by submersion in the dye liquor in the presence of ultrasound and no surface cracking was evident in scanning electron microscopy images. Some cuticle structure changes occurred with turning up or ripping off of the cuticle tips evident. Both wash and rub fastness were improved for ultrasonically dyed fiber with dyeing temperatures of 70 and 80 °C being suitable for the low-temperature dyeing of wool.

TMIC-29. MYELOID DERIVED SUPPRESSOR CELLS’ TRAFFICKING INTO GBM IS REGULATED BY CXCR2 SIGNALING

Survival of glioma patients treated with the current standard of care remains dismal. Immunotherapeutic approaches harnessing the cytotoxic and memory potential of the host immune system have shown great benefit in other cancers. It is imperative to develop multipronged approaches when aiming to generate a robust anti-tumor immune response. Our results show that MDSCs constitute >40% of the tumor-infiltrating immune cells. These cells express IL-4Rα, inducible nitric oxide synthase (iNOS), arginase, programmed death ligand 1 (PDL1), and CD80, molecules that are critically involved in antigen-specific T cell suppression. MDSC depletion strongly enhanced the efficacy of herpes simplex type-I thymidine kinase (TK) plus Fms-like tyrosine kinase ligand (Flt3L)-mediated immune stimulatory gene therapy. Also, combining PDL1 or CTLA-4 immune checkpoint blockade greatly improved the efficacy of TK/Flt3L gene therapy. Overall, our data indicates that strategies that inhibit MDSC recruitment to the GBM TME hold great promise for increasing the efficacy of gene therapy-mediated immunotherapies for GBM. Experiments to determine the mechanism of MDSC trafficking to the TME point towards the receptor CXCR2. Microarray analysis of glioma cell lines and neurospheres showed elevated levels of CXCL1 and CXCL2 mRNA. CXCR2 inhibitor suppressed the migration of MDSCs towards GBM cells in a transwell migration assay. Conditioned media from GBM neurospheres also enhanced the permeability of an in vitro blood brain barrier model as indicated by the increased migration of size exclusion dyes. Blocking CXCR2 on endothelial cells and/or pericytes abrogated this increase in BBB permeability. Thus our data suggests that the CXCR2 receptor can regulate MDSC migration into the TME by directly impacting MDSC migration or by altering the BBB permeability. Future experiments are aimed at using the Vav-Cre mediated conditional deletion of CXCR2 on myeloid cells and pharmacological inhibition of CXCR2 to investigate its role in glioma progression in vivo.

Identifying connexin expression and determining gap junction intercellular communication in rainbow trout cells.

Gap junctions are groups of membrane-bound channels that allow the passage of small molecules and ions between cells, permitting cell-cell communication. Because of their importance in cell homeostasis, gap junction presence and function were characterized in three commonly studied rainbow trout cell lines, namely RTgill-W1, RTgutGC, and RTG-2. Firstly, gap junction presence was determined by screening for gap junction protein alpha 7 and alpha 1 (GJA7 and GJA1) presence at the transcript level and GJA7 at the protein level. GJA7 was successfully identified at both the transcript and protein levels, and GJA1 was detected at the transcript level in all three cell lines. This is the first report of a GJA7 full-length transcript sequence in rainbow trout cells. Gap junction function, as determined by gap junction intercellular communication (GJIC), was examined using Lucifer yellow dye migration with the scrape and load technique; visualized by fluorescence microscopy. Phorbol 12-myristate 13-acetate (PMA), a gap junction inhibitor, was used to confirm the presence of functional gap junctions. Effects of serum deprivation on GJIC were also monitored; 24-h serum deprivation resulted in greater dye migration compared with 30-min serum deprivation. Both RTG-2 and RTgill-W1 showed significant dye migration that was inhibited by PMA while RTgutGC did not. Human foreskin fibroblast (HFF-1) cells were used as a positive control for gap junction presence and function. Taken together, our study shows that rainbow trout cells express connexin transcripts and proteins, and RTG-2 and, to a lesser extent, RTgill-W1 cells are able to perform GJIC.

Quantification of the asymmetric migration of the lipophilic dyes, DiO and DiD, in homotypic co-cultures of chondrosarcoma SW-1353 cells.

DiO and DiD are lipophilic cell labelling dyes used in the staining of cells in vivo and in vitro. The aim of the present study was to quantify the asymmetrical distribution of dyes in co-cultured cells and to measure the intercellular transfer of DiO and DiD. DiO and DiD were applied separately to stain two identical populations of SW-1353 human chondrosarcoma cells that were subsequently co-cultured (homotypic co-culture). The intercellular migration of dyes in the co-cultured cells was measured by flow cytometry and recorded under a fluorescent microscope. DiD and DiO caused no effect on the proliferation of cells, the degradation rate of the two dyes was comparable and crossover effects between dyes were negligible. The results of the present study suggested that asymmetrical intercellular migration of DiD and DiO was responsible for the asymmetrical distribution of these dyes in co-cultured cells. To take advantage of the lipophilic dyes migration in the double-stained co-cultured cells we suggest to apply mixed-dyes controls prior to the flow cytometric analysis. These controls are performed by staining cells with a 1:1 mix of the two dyes and would enable the estimation of the intensity of intercellular contact in co-culture systems. A 1:1 premix of DiO and DiD was applied to estimate cellular effect on intercellular exchange of lipid dyes in co-cultures incubated with cycloheximide and cytochalasin B. The cellular effect contributed 6–7% of intercellular migration of the lipophilic dyes, DiO and DiD. The majority of the observed intercellular transfer of these dyes was due to non-cellular, passive transfer.

Sustained release of the candidate antiretroviral peptides T-1249 and JNJ54310516-AFP from a rod insert vaginal ring.

Administration of biomacromolecular drugs in effective quantities from conventional vaginal rings is hampered by poor drug permeability in the polymers from which rings are commonly constructed. Here, we report the formulation development and testing of rod insert rings for sustained release of the candidate antiretroviral peptides T-1249 and JNJ54310516-AFP (JNJ peptide), both of which have potential as HIV microbicides. Rod inserts were prepared comprising antiviral peptides T-1249 or JNJ peptide in combination with a hydrophilic excipient (sodium chloride, sodium glutamate, lactose or zinc acetate) dispersed at different loadings within a medical grade silicone elastomer. The inserts were tested for weight change and swelling when immersed in simulated vaginal fluid (SVF). Dye migration into the inserts was also assessed visually over 28 days. In vitro release of T-1249 and JNJ peptide from rings containing various insert types was tested. Weight change and degree of swelling of rods immersed in SVF was dependent on the type and concentration of excipient present. The rods displayed the following rank order in terms of weight change: sodium glutamate > zinc acetate ≈ sodium chloride > lactose. The weight change and degree of swelling of the inserts did not correlate with the level of dye uptake observed. In vitro release of T-1249 was improved through addition of lactose, sodium chloride and sodium glutamate, while release of JNJ peptide was improved through addition of sodium chloride or sodium glutamate. Sustained release of hydrophobic peptides can be achieved using a rod insert ring design formulated to include a hydrophilic excipient. Release rates were dependent upon the type of excipient used. The degree of release improvement with different inserts partially reflects their ability to imbibe surrounding fluid and swell in aqueous environments.

Suitability of polystyrene as a functional barrier layer in coloured food contact materials

Functional barriers in food contact materials (FCMs) are used to prevent or reduce migration from inner layers in multilayer structures to food. The effectiveness of functional barrier layers was investigated in coloured polystyrene (PS) bowls due to their intended condition of use with hot liquids such as soups or stew. Migration experiments were performed over a 10-day period using USFDA-recommended food simulants (10% ethanol, 50% ethanol, corn oil and Miglyol) along with several other food oils. At the end of the 10 days, solvent dyes had migrated from the PS bowls at 12, 1 and 31 000 ng cm–2 into coconut oil, palm kernel oil and Miglyol respectively, and in coconut oil and Miglyol the colour change was visible to the human eye. Scanning electron microscope (SEM) images revealed that the functional barrier was no longer intact for the bowls exposed to coconut oil, palm kernel oil, Miglyol, 10% ethanol, 50% ethanol and goat’s milk. Additional tests showed that 1-dodecanol, a lauryl alcohol derived from palm kernel oil and coconut oil, was present in the PS bowls at an average concentration of 11 mg kg–1. This compound is likely to have been used as a dispersing agent for the solvent dye and aided the migration of the solvent dye from the PS bowl into the food simulant. The solvent dye was not found in the 10% ethanol, 50% ethanol and goat’s milk food simulants above their respective limits of detection, which is likely to be due to its insolubility in aqueous solutions. A disrupted barrier layer is of concern because if there are unregulated materials in the inner layers of the laminate, they may migrate to food, and therefore be considered unapproved food additives resulting in the food being deemed adulterated under the Federal Food Drug and Cosmetic Act.

An in vitro comparision of apical leakage in immediate versus delayed post space preparation using EndoREZ and RoekoSeal root canal sealers

Context: The newer resin and silicone-based sealers have a shorter setting time when compared to conventional zinc oxide-based sealers. This factor may influence the effect of the timing of post space preparation on the integrity of remaining apical root canal filling. Aims: The purpose of this study was to evaluate the apical dye leakage of samples obturated with EndoREZ and RoekoSeal root canal sealers with reference to the timing (immediate and delayed) of post space preparation. Settings and Design: An in vitro study using extracted human teeth as study samples and the method of apical dye penetration to determine the apical micro-leakage microscopically. Materials and Methods: Seventy single-rooted anterior extracted teeth were instrumented and divided into ix groups; fifteen teeth in groups 1, 2, 3, and 4 and five teeth in groups 5 and 6. In groups 1 and 2, specimens were obturated with warm vertical compaction and EndoREZ sealer. In groups 3 and 4, specimens were obturated with warm vertical compaction and RoekoSeal sealer. Immediate post space was prepared in groups 1 and 3. The samples in groups 2 and 4, the post space was prepared after placing the teeth in saline at 37°C for 1 week. Groups 5 and 6 represented positive and negative controls, respectively. The samples were then placed in methylene blue for 72 hours. The samples were then sectioned longitudinally and the amount of linear apical dye migration was evaluated. Statistical Analysis Used: One-way analysis of variance (ANOVA) and multiple pair-wise comparisions using Tukeys multiple post hoc procedures. Results: There was a statistically significant difference in the mean apical dye micro-leakage values in between the EndoREZ and RoekoSeal groups, i. e., groups 1, 2 and groups 3, 4. Conclusions: EndoREZ root canal sealer groups exhibited a higher mean apical dye micro-leakage value as compared to the RoekoSeal root canal sealer groups. Immediate post space preparation resulted in a relatively lower mean apical dye micro-leakage as compared to delayed post space preparation, but the difference was not statistically significant.

HIV-1 Tat C phosphorylates VE-cadherin complex and increases human brain microvascular endothelial cell permeability.

BackgroundHuman brain microvascular endothelial cells (hBMVECs) are integral part of the blood brain barrier. Post-translational modifications of adherens junction proteins regulate the permeability of human brain microvascular endothelial cells. Pro-inflammatory signals can induce tyrosine phosphorylation of adherens junction proteins. The primary objective of this work is to provide a molecular model; how the HIV-1 Tat protein can compromise the BBB integrity and eventually lead to neurological consequences. We exposed hBMVECs to recombinant HIV-1 clade C Tat protein to study the effect of HIV-1 Tat C on permeability of hBMVECs. Trans-endothelial electrical resistance and fluorescent dye migration assay have been used to check the permeability of hBMVECs. DCFDA staining has been used for intracellular reactive oxygen species (ROS) detection. Western blotting has been used to study the expression levels and co-immunoprecipitation has been used to study the interactions among adherens junction proteins.ResultsHIV-1 Tat C protein induced NOX2 and NOX4 expression level and increased intracellular ROS level. Redox-sensitive kinase; PYK2 activation led to increased tyrosine phosphorylation of VE-cadherin and β-catenin, leading to disruption of junctional assembly. The dissociation of tyrosine phosphatases VE-PTP and SHP2 from cadherin complex resulted into increased tyrosine phosphorylation of VE-cadherin and β-catenin in HIV-1 Tat C treated hBMVECs.ConclusionUnrestricted phosphorylation of junctional proteins in hBMVECs, in response to HIV-1 Tat C protein; leads to the disruption of junctional complexes and increased endothelial permeability.