The adhesive strength of fiber post-to-canal dentin with Aniline green, Fotoenticine activated by PDT, green tea, and ozone as a final irrigant

AIM

The effect of novel final disinfection protocols Malachite green (MG), Fotoenticine® (FTC), Green tea extract (GTE), and Ozonated water (OW) on the bond strength of prefabricated glass fiber posts (PGFP) adhered to canal dentin.

MATERIAL AND METHOD

The canals of fifty premolars with closed apices were cleansed and obturated. The specimens were randomly assigned to one of five groups based on the final irrigant used, with the control group receiving NaOCl+EDTA and the experimental groups receiving MG, FTC, OW, and GTE. The GFP was cemented with a self-etching, dual-cure paste; the bond strength was estimated with a universal testing machine; and failure analysis was conducted with a stereomicroscope.

RESULTS

The highest PBS was observed in the coronal third of Group 4 (using ozonated water as the final irrigant), whereas the lowest bond integrity was observed in the apical section of Group 2 (1.02-0.54 MPa) using Malachite green as the final irrigant. Group 1, Group 4, and Group 5 exhibited no significant difference in the bond integrity of GFP to dentin when compared to Group 2 (p>0.05). In addition, comparable bond score values were obtained for Groups 2 and 3 (p>0.05).

CONCLUSION

The results of this study suggest that OW and GTE may be effective final disinfectants for root canals, as they increase the bond strength of resin-luting cement.

A Nickel-Containing Polyoxomolybdate as an Efficient Antibacterial Agent for Water Treatment

In view of the water pollution issues caused by pathogenic microorganisms and harmful organic contaminants, nontoxic, environmentally friendly, and efficient antimicrobial agents are urgently required. Herein, a nickel-based Keggin polyoxomolybdate [Ni(L)(HL)]₂H[PMo₁₂O₄₀] 4H₂O (1, HL = 2-acetylpyrazine thiosemicarbazone) was prepared via a facile hydrothermal method and successfully characterized. Compound 1 exhibited high stability in a wide range of pH values from 4 to 10. 1 demonstrated significant antibacterial activity, with minimum inhibitory concentration (MIC) values in the range of 0.0019–0.2400 µg/mL against four types of bacteria, including Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli), and Agrobacterium tumefaciens (A. tumefaciens). Further time-kill studies indicated that 1 killed almost all (99.9%) of E. coli and S. aureus. Meanwhile, the possible antibacterial mechanism was explored, and the results indicate that the antibacterial properties of 1 originate from the synergistic effect between [Ni(L)(HL)]⁺ and [PMo₁₂O₄₀]³⁻. In addition, 1 presented effective adsorption of basic fuchsin (BF) dyes. The kinetic data fitted a pseudo-second-order kinetic model well, and the maximum adsorption efficiency for the BF dyes (29.81 mg/g) was determined by the data fit of the Freundlich isotherm model. The results show that BF adsorption was dominated by both chemical adsorption and multilayer adsorption. This work provides evidence that 1 has potential to effectively remove dyes and pathogenic bacteria from wastewater.

Role of TRPV4-P2X7 Pathway in Neuropathic Pain in Rats with Chronic Compression of the Dorsal Root Ganglion

Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable non-selective cation channel that is involved in the development of neuropathic pain. P2X7 receptor (P2X7) belongs to a class of ATP-gated nonselective cation channels that plays an important role in neuropathic pain. Nevertheless, little is known about the interaction between them for neuropathic pain. In this paper, we investigated role of TRPV4-P2X7 pathway in neuropathic pain. We evaluated the effect of TRPV4-P2X7 pathway on neuropathic pain in a chronic compression of the dorsal root ganglion (DRG) (hereafter termed CCD) model. We analyzed the effect of P2X7 on mechanical and thermal hyperalgesia mediated by TRPV4 in CCD. Furthermore, we assessed the effect of TRPV4 on the expression of P2X7 and the release of IL-1β and IL-6 in DRG after CCD. We found that intraperitoneal injection of TRPV4 agonist GSK-1016790A led to a significant increase of mechanical and thermal hyperalgesia in CCD, which was partially suppressed by P2X7 blockade with antagonist Brilliant Blue G (BBG). Then, we further noticed that GSK-1016790A injection increased the P2X7 expression of CCD, which was decreased by TRPV4 blockade with antagonist RN-1734 and HC-067047. Furthermore, we also discovered that the expressions of IL-1β and IL-6 were upregulated by GSK-1016790A injection but reduced by RN-1734 and HC-067047. Our results provide evidence that P2X7 contributes to development of neuropathic pain mediated by TRPV4 in the CCD model, which may be the basis for treatment of neuropathic pain relief.

Comparative proteomic analysis provides insight into the key proteins as potential targets underlying the effect of malachite green against Ichthyophthirius multifiliis

Target identification is important for drug discovery. Unfortunately, no drug targets have been found in Ichthyophthirius multifiliis until now and further limited development of the novel drug for Ichthyophthiriasis. In this study, an iTRAQ-based quantitative proteomic analysis was used to find the target of malachite green (MG), exhibiting greater efficacy than the existing drugs, against I. multifiliis trophonts in situ. We also verified the proteomic results by RT-qPCR, TEM and cell apoptosis assay. Our results showed that major variations in protein abundance were found among many of the ribosome proteins, indicating ribosome might be a candidate target. Furthermore, GO and KEGG pathway analyses of differentially expressed proteins (DEPs) revealed that ribosome and PI3K-Akt signalling pathway were remarkably enriched. Taken together, the above DEPs were also verified by RT-qPCR and morphological observations. This study provides insights into the key proteins enriched in PI3K-Akt signal pathway and ribosome pathway as potential targets of MG killing I. multifiliis, which could be served as targets for other less toxic drugs and be tested as potential treatments for I. multifiliis.

P2X7 receptor antagonist BBG inhibits endoplasmic reticulum stress and pyroptosis to alleviate postherpetic neuralgia

Postherpetic neuralgia (PHN) is the most common complication of acute herpes zoster. The treatment of PHN remains a challenge for clinical pain management. The present study investigated the P2X7 receptor antagonist brilliant blue G (BBG) whether inhibits endoplasmic reticulum stress and pyroptosis (a necrotic form of cell death) and alleviates PHN. Varicella zoster virus (VZV)-infected CV-1 cells were used to induce PHN model. Mechanical paw withdrawal thresholds were measured using an ascending series of von Frey filaments. Immunohistochemistry was used to detect the expression of P2X7R in nerve tissues. Western blot was used to determine the expression of endoplasmic reticulum (ER) stress and pyroptosis-related molecules. The expression of IL-1β and IL-18 in tissue homogenate was detected by ELISA. The PHN rat has the lower paw withdrawal threshold, but higher expression of P2X7 in nerve tissues. And, endoplasmic reticulum stress was activated and pyroptosis was increased in PHN rats. BBG can decrease pain thresholds and reduce ER stress and pyroptosis in PHN rats. In addition, ER stress activator tunicamycin (TM) can reverse the effect of BBG on the paw withdrawal thresholds, endoplasmic reticulum stress, and pyroptosis. Therefore, P2X7 receptor antagonist BBG alleviates PHN by activating ER stress and reducing pyroptosis.

P2X7 receptor antagonism increases regulatory T cells and reduces clinical and histological graft-versus-host disease in a humanised mouse model

Graft-versus-host disease (GVHD) is a severe inflammatory response arising from allogeneic haematopoietic stem cell transplantation. Previous studies revealed that antagonism of the P2X7 receptor with Brilliant Blue G (BBG) reduced liver GVHD but did not alter clinical GVHD in a humanised mouse model. Therefore, the present study aimed to trial a modified injection regime using more frequent dosing of BBG to improve outcomes in this model of GVHD. NOD-scid IL2Rγnull (NSG) mice were injected intraperitoneally (i.p.) with 10 × 106 human peripheral blood mononuclear cells (hPBMCs) (day 0), then daily with BBG (50 mg/kg) or saline (days 0-10). BBG significantly reduced clinical score, mortality and histological GVHD compared with saline treatment (endpoint). BBG significantly increased proportions of human regulatory T cells (Tregs) and human B cells and reduced serum human interferon-γ compared with saline treatment prior to development of clinical GVHD (day 21). To confirm the therapeutic benefit of P2X7 antagonism, NSG mice were injected i.p. with 10 × 106 hPBMCs (day 0), then daily with pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) (300 mg/kg) or saline (days 0-10). PPADS increased human Treg proportions compared with saline treatment (day 21), but potential clinical benefits were confounded by increased weight loss with this antagonist. To investigate the role of P2X7 antagonism on Treg survival, hPBMCs were cultured in reduced serum conditions to promote cell death. BBG increased proportions of Tregs (and B cells) compared with saline under these conditions. In conclusion, P2X7 antagonism reduces clinical and histological GVHD in a humanised mouse model corresponding to an increase in human Tregs.

Effect of Photodynamic Therapy on Microorganisms Responsible for Dental Caries: A Systematic Review and Meta-Analysis

The aim of this study was to perform a systematic review of the literature followed by a meta-analysis about the efficacy of photodynamic therapy (PDT) on the microorganisms responsible for dental caries. The research question and the keywords were constructed according to the PICO strategy. The article search was done in Embase, Lilacs, Scielo, Medline, Scopus, Cochrane Library, Web of Science, Science Direct, and Pubmed databases. Randomized clinical trials and in vitro studies were selected in the review. The study was conducted according the PRISMA guideline for systematic review. A total of 34 articles were included in the qualitative analysis and four articles were divided into two subgroups to perform the meta-analysis. Few studies have achieved an effective microbial reduction in microorganisms associated with the pathogenesis of dental caries. The results highlight that there is no consensus about the study protocols for PDT against cariogenic microorganisms, although the results showed the PDT could be a good alternative for the treatment of dental caries.

Low-cost internal controls for detection of Giardia cysts in water samples

Giardia cysts stained with hot carbolfuchsin were used as internal controls in a concentration method for surface water samples. The morphological integrity of stained cysts and the stain's stability and intensity were tested with each of the chemical reagents used in the aluminum sulfate flocculation method. No alterations in morphology or color were noted. The stained cyst preparation has a low cost, high stability, and suitability for both light and immunofluorescent microscopy, making it affordable to researchers in low- and middle-income countries.

The role of P2X7R/ERK signaling in dorsal root ganglia satellite glial cells in the development of chronic postsurgical pain induced by skin/muscle incision and retraction (SMIR)

The mechanisms of chronic postsurgical pain remain to be elucidated. We reported here that skin/muscle incision and retraction (SMIR), a rat model of postsurgical pain, phosphorylated the extracellular regulated protein kinases (ERK) signaling components c-Raf, MEK (ERK kinase) and ERK1/2 in lumbar 3 dorsal root ganglion (L3 DRG) in rats. Intrathecal injection of ERK specific inhibitor SCH772984 suppressed the mechanical allodynia induced by SMIR. Furthermore, SMIR upregulated tumor necrosis factor alpha (TNFα) in L3 DRG, which could be inhibited by SCH772984. Intrathecal injection of TNF antagonist Etanercept could also inhibit the mechanical allodynia and the increased ERK phosphorylation in L3 DRG induced by SMIR. In addition, immunofluorescent data showed that P2X7R was located exclusively in GFAP labeled satellite glial cells and was highly colocalized with p-ERK1/2 following SMIR. Pretreatment with P2X7R antagonist Brilliant Blue G (BBG) could also block the mechanical allodynia, inhibited the phosphorylation of c-Raf, MEK, ERK1/2, and decrease the expression of TNF-α. Finally, intrathecal injection of BzATP produced mechanical allodynia and induced ERK phosphorylation in satellite glial cells in L3 DRG. Thus, P2X7R activation in satellite glial cells in L3 DRG, leading to a positive feedback between ERK pathway activation and TNF-α production, is suggested to be involved in the induction of chronic postsurgical pain following SMIR.

Inhibition of inflammasome activation improves lung acute injury induced by carrageenan in a mouse model of pleurisy

The inflammasome NLRP3 is a molecular pathway activated by a wide range of cellular insults to elicit innate immune defenses through the activation of caspase-1 and the maturation of proinflammatory cytokines, such as IL-1β and IL-18. The expression of NRLP3 is abnormally elevated in numerous human inflammatory diseases, including pulmonary diseases. An injection of carrageenan (CAR) into the pleural cavity triggered an acute inflammatory response, leading to tissue damage, inflammatory exudates, leukocyte infiltration, and increased myeloperoxidase activity. The aim of this study was to assess the effect of the inflammasome blocking agents BAY 11-7082 (30 mg/kg, i.p.) and Brilliant Blue G (BBG) (45.5 mg/kg, i.p.) in a mouse model of CAR-induced pleurisy. Treatment with BAY 11-7082 or BBG 1 h after CAR injection attenuated pulmonary membrane thickening and polymorphonuclear leukocyte infiltration, reduced NF-κB translocation in the nucleus, and inhibited the assembly of the NRLP3/ASC/caspase-1 complex. Treatment with BAY 11-7082 or BBG also down-regulated iNOS, nitrotyrosine, and poly-ADP-ribosyl polymerase expression and inhibited CAR-induced apoptosis. Our results demonstrate that treatment with inflammasome-blocking agents can significantly reduce the development of acute CAR-induced lung injury.-Fusco, R. Gugliandolo, E., Biundo, F., Campolo, M., Di Paola, R., Cuzzocrea, S. Inhibition of inflammasome activation improves lung acute injury induced by carrageenan in a mouse model of pleurisy.

The Beneficial Effects of P2X7 Antagonism in Rats with Bile Duct Ligation-induced Cirrhosis

Splanchnic angiogenesis in liver cirrhosis often leads to complications as gastroesophageal variceal hemorrhage and the treatment efficacy is adversely affected by poor portal-systemic collateral vasoresponsiveness related to nitric oxide (NO). Purinergic receptor subtype P2X7 participates in the modulation of inflammation, angiogenesis, fibrogenesis and vasoresponsiveness, but the relevant influence in cirrhosis is unknown. Common bile duct-ligated (CBDL) or sham-operated Spraque-Dawley rats received brilliant blue G (BBG, a P2X7 antagonist and food additive) or vehicle from the 15th to 28th day after operations, then hemodynamics, mesenteric angiogenesis, portal-systemic shunting, liver fibrosis, and protein expressions of angiogenic and fibrogenic factors were evaluated. The influence of oxidized ATP (oATP, another P2X7 receptor antagonist) on the collateral vasoresponsiveness to arginine vasopressin (AVP) was also surveyed. BBG decreased superior mesenteric artery (SMA) flow, portal-systemic shunting, mesenteric vascular density, and mesenteric protein expressions of vascular endothelial growth factor (VEGF), VEGF receptor 2 (VEGFR2), phospho (p)-VEGFR2, platelet-derived growth factor (PDGF), PDGF receptor beta (PDGFRβ), cyclooxygenase (COX)-1, COX-2, and endothelial NO synthase (eNOS) in CBDL rats. BBG also ameliorated liver fibrosis and down-regulated hepatic interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), PDGF, IL-1β, transforming growth factor-beta (TGF-β), p-extracellular-signal-regulated kinases (ERK), and alpha-smooth muscle actin (α-SMA) expressions in CBDL rats. The collateral vasocontractility to AVP was enhanced by oATP. oATP down-regulated eNOS, inducible NOS (iNOS), VEGF, Akt, p-Akt, and nuclear factor-kappa B (NF-κB) expressions in splenorenal shunt, the most prominent intra-abdominal collateral vessel in rodents. P2X7 antagonism alleviates splanchnic hyperemia, severity of portal-systemic shunting, mesenteric angiogenesis, liver fibrosis, and enhances portal-systemic collateral vasoresponsiveness in cirrhotic rats. P2X7 blockade may be a feasible strategy to control cirrhosis and complications.

The selective antagonism of P2X7 and P2Y1 receptors prevents synaptic failure and affects cell proliferation induced by oxygen and glucose deprivation in rat dentate gyrus

Purinergic P2X and P2Y receptors are broadly expressed on both neurons and glial cells in the central nervous system (CNS), including dentate gyrus (DG). The aim of this research was to determine the synaptic and proliferative response of the DG to severe oxygen and glucose deprivation (OGD) in acute rat hippocampal slices and to investigate the contribution of P2X₇ and P2Y₁ receptor antagonism to recovery of synaptic activity after OGD. Extracellular field excitatory post-synaptic potentials (fEPSPs) in granule cells of the DG were recorded from rat hippocampal slices. Nine-min OGD elicited an irreversible loss of fEPSP and was invariably followed by the appearance of anoxic depolarization (AD). Application of MRS2179 (selective antagonist of P2Y₁ receptor) and BBG (selective antagonist of P2X₇ receptor), before and during OGD, prevented AD appearance and allowed a significant recovery of neurotransmission after 9-min OGD. The effects of 9-min OGD on proliferation and maturation of cells localized in the subgranular zone (SGZ) of slices prepared from rats treated with 5-Bromo-2′-deoxyuridine (BrdU) were investigated. Slices were further incubated with an immature neuron marker, doublecortin (DCX). The number of BrdU⁺ cells in the SGZ was significantly decreased 6 hours after OGD. This effect was antagonized by BBG, but not by MRS2179. Twenty-four hours after 9-min OGD, the number of BrdU⁺ cells returned to control values and a significant increase of DCX immunofluorescence was observed. This phenomenon was still evident when BBG, but not MRS2179, was applied during OGD. Furthermore, the P2Y₁ antagonist reduced the number of BrdU⁺ cells at this time. The data demonstrate that P2X₇ and P2Y₁ activation contributes to early damage induced by OGD in the DG. At later stages after the insult, P2Y₁ receptors might play an additional and different role in promoting cell proliferation and maturation in the DG.

Role of P2X purinoceptor 7 in neurogenic pulmonary edema after subarachnoid hemorrhage in rats

Introduction

Neurogenic pulmonary edema (NPE) is an acute and serious complication after subarachnoid hemorrhage (SAH) with high mortality. The present study aimed to test the therapeutic potential of brilliant blue G (BBG), a selective P2X purinoceptor 7 (P2X7R) antagonist, on NPE in a rat SAH model.

Methods

SAH was induced by endovascular perforation. 86 Sprague-Dawley rats were randomly divided into sham, vehicle-, or BBG-treatment groups. Mortality, body weight, SAH grading, neurological deficits, NPE clinical symptoms, and pulmonary index were measured at 24 hours following SAH. Western blot, gelatin zymography, lung histopathology, and immunofluorescence staining were performed in the left lung lobe to explore the underlying mechanisms at 24 hours post-surgery.

Results

The incidence of clinical symptoms was correlated with pulmonary index. P2X7R and the marker of alveolar type I epithelial cells (the mucin-type glycoprotein T1-α) immunoreactivities were generally co-localized. BBG administration decreased mature interleukin-1β, myeloperoxidase, and matrix metallopeptidase-9 activation, but increased tight junction proteins, such as ZO-1 and occludin, which ameliorated pulmonary edema via anti-inflammation and improved neurological deficits.

Conclusion

P2X7R inhibition prevented NPE after SAH by attenuating inflammation. Thus, BBG is a potential therapeutic application for NPE after SAH and warrants further research.

[A case of prolonged reduction in arterial oxygen saturation measured by pulse oxymetry after administering patent blue in an elderly patient]

A 93-year-old woman with a vulvar cancer was scheduled for resection of the tumor and sentinel lymph node biopsy under general anesthesia. At the beginning of the operation, a total of 20 ml of 2.5% patent blue was injected into the tumor and the surroundings to identify sentinel lymph node. After the injection, arterial oxygen saturation measured by pulse oximetry gradually dropped to 80%. The oxygen saturation recovered to the original level at 300 min post-injection, but blue pigmentation distributed throughout her body persisted until the following day. Her perioperative course was uneventful. In case of desaturation after dye injection, it is important to rule out true hypoxemia immediately by performing arterial blood gas analysis. Conversely, CO-oximetry is not necessarily useful for accurate diagnosis.

Dynamic increase in extracellular ATP accelerates photoreceptor cell apoptosis via ligation of P2RX7 in subretinal hemorrhage

Photoreceptor degeneration is the most critical cause of visual impairment in age-related macular degeneration (AMD). In neovascular form of AMD, severe photoreceptor loss develops with subretinal hemorrhage due to choroidal neovascularization (CNV), growth of abnormal blood vessels from choroidal circulation. However, the detailed mechanisms of this process remain elusive. Here we demonstrate that neovascular AMD with subretinal hemorrhage accompanies a significant increase in extracellular ATP, and that extracellular ATP initiates neurodegenerative processes through specific ligation of Purinergic receptor P2X, ligand-gated ion channel, 7 (P2RX7; P2X7 receptor). Increased extracellular ATP levels were found in the vitreous samples of AMD patients with subretinal hemorrhage compared to control vitreous samples. Extravascular blood induced a massive release of ATP and photoreceptor cell apoptosis in co-culture with primary retinal cells. Photoreceptor cell apoptosis accompanied mitochondrial apoptotic pathways, namely activation of caspase-9 and translocation of apoptosis-inducing factor (AIF) from mitochondria to nuclei, as well as TUNEL-detectable DNA fragmentation. These hallmarks of photoreceptor cell apoptosis were prevented by brilliant blue G (BBG), a selective P2RX7 antagonist, which is an approved adjuvant in ocular surgery. Finally, in a mouse model of subretinal hemorrhage, photoreceptor cells degenerated through BBG-inhibitable apoptosis, suggesting that ligation of P2RX7 by extracellular ATP may accelerate photoreceptor cell apoptosis in AMD with subretinal hemorrhage. Our results indicate a novel mechanism that could involve neuronal cell death not only in AMD but also in hemorrhagic disorders in the CNS and encourage the potential application of BBG as a neuroprotective therapy.

Double staining cytologic samples with quantitative Feulgen-thionin and anti-Ki-67 immunocytochemistry as a method of distinguishing cells with abnormal DNA content from normal cycling cells

OBJECTIVE

To improve ploidy analysis in the detection of high-grade cervical dysplasias by combining it with anti-Ki-67 immunocytochemistry in a double staining procedure to distinguish between cells with abnormal DNA content and normal cycling cells.

STUDY DESIGN

Cervical cytology specimens from 49 patients with various diagnoses, mostly dysplasias, from a previous study were used. Samples were double stained with Feulgen-thionin and anti-Ki-67 immunocytochemistry. Ki-67-negative cells were noncycling, so nondiploid Ki-67-negative cells were likely truly abnormal cells.

RESULTS

The area under the receiver operating characteristic curve for the ability to identify high-grade dysplasias was 0.73 for double staining and 0.74 for thionin-only ploidy analysis on Cytospin specimens. At 90% specificity, sensitivities for double staining and thionin alone were 45% and 32%, respectively, but the difference was not statistically significant.

CONCLUSION

Double staining with Feulgen-thionin and anti-Ki-67 immunocytochemistry does not improve the ability of ploidy analysis of cervical cytology specimens to separate high-grade and low-grade dysplasias, but our insights into the technical aspects of double staining, especially the effects of antigen retrieval, give hope that this technique could be applied to other immunocytochemical stains that would have a greater ability to improve ploidy analysis.

Anti-prion activity of Brilliant Blue G

Background

Prion diseases are fatal neurodegenerative disorders with no effective therapy currently available. Accumulating evidence has implicated over-activation of P2X7 ionotropic purinergic receptor (P2X7R) in the progression of neuronal loss in several neurodegenerative diseases. This has led to the speculation that simultaneous blockade of this receptor and prion replication can be an effective therapeutic strategy for prion diseases. We have focused on Brilliant Blue G (BBG), a well-known P2X7R antagonist, possessing a chemical structure expected to confer anti-prion activity and examined its inhibitory effect on the accumulation of pathogenic isoforms of prion protein (PrPres) in a cellular and a mouse model of prion disease in order to determine its therapeutic potential.

Principal Findings

BBG prevented PrPres accumulation in infected MG20 microglial and N2a neural cells at 50% inhibitory concentrations of 14.6 and 3.2 µM, respectively. Administration of BBG in vivo also reduced PrPres accumulation in the brains of mice with prion disease. However, it did not appear to alleviate the disease progression compared to the vehicle-treated controls, implying a complex role of P2X7R on the neuronal degeneration in prion diseases.

Significance

These results provide novel insights into the pathophysiology of prion diseases and have important implications for the treatment.

Effects of propofol on P2X7 receptors and the secretion of tumor necrosis factor-α in cultured astrocytes

Upon CNS injury, adenosine-5'-triphosphate is released and acts on P2X7 receptors, which might influence many cytokines secretion from glial cells and, in turn, affects the survival of neurons. Propofol, an intravenous anesthetic, has been shown to provide neuroprotective effect. However, the effect of propofol on astrocyte-associated processes remains to be clarified. In this study, we investigated the effects of propofol on P2X7 activity in astrocytes and tumor necrosis factor-α (TNF-α) secretion from these cells and thereby to infer the possible role(s) of glial P2X7 receptors in propofol neural protective effects. Whole-cell patch clamp results showed that in clinically relevant concentrations (3.3, 10 or 33 μM), propofol increased the P2X7 current amplitudes significantly and propofol in 10 μM extended the inactivation times of P2X7 receptors. Enzyme-linked immunosorbent assay showed that propofol increased the secretion of TNF-α from astrocytes in high concentration (300 μM), while inhibited in clinically relevant concentration (10 μM). Both of these effects were not influenced by Brilliant blue G. These results suggest that in clinically relevant concentrations, propofol increases the activity of P2X7 receptors in activated astrocytes, but this does not contribute to the downregulation of the secretion of TNF-α.

Decolorization of malachite green, decolorization kinetics and stoichiometry of ozone-malachite green and removal of antibacterial activity with ozonation processes

This study aimed to identify degradation intermediates and to investigate the stoichiometry of decolorization and degradation, decolorization kinetics, and removal of antibacterial activity of malachite green (MG) using ozonization processes. The decolorization of MG was optimal at an acidic pH value of 3 based on molecular ozone attack on MG molecules. The stoichiometric ratio of decolorization between ozone and MG was calculated to be 7.0 with a regression coefficient of 0.995, whereas the ratio for degradation was calculated as 13.1 with a regression coefficient of 0.998. With MG concentrations in the range of 0.30-1.82 mM, the concentration of decolorized MG increased with higher initial concentrations of MG, whereas the ozonolytic decolorization rates of MG, decreased with increasing initial concentration. The pseudo-first-order degradation rate constants (k') decreased with the initial concentration and ranged from 0.769 to 0.223 min(-1). Twelve different intermediates were produced during the ozonation of MG with ozonation times between 5 min and 30 min and were identified by GC-MS. Although 86% of MG in the reaction mixture was removed by ozonation after 10 min, the decrease of antibacterial activity was very low (10%) for Bacillus subtilis and Staphylococcus epidermidis because the degradation intermediates, phenol and benzoic acid, also have antibacterial activity. The antibacterial activity of both MG and its intermediates were removed successfully with ozonation times above 26 min.

Purinergic receptor functionality is necessary for infection of human hepatocytes by hepatitis delta virus and hepatitis B virus

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) are major sources of acute and chronic hepatitis. HDV requires the envelope proteins of HBV for the processes of assembly and infection of new cells. Both viruses are able to infect hepatocytes though previous studies have failed to determine the mechanism of entry into such cells. This study began with evidence that suramin, a symmetrical hexasulfated napthylurea, could block HDV entry into primary human hepatocytes (PHH) and was then extrapolated to incorporate findings of others that suramin is one of many compounds that can block activation of purinergic receptors. Thus other inhibitors, pyridoxal-phosphate-6-azophenyl-2′,4′-disulfonate (PPADS) and brilliant blue G (BBG), both structurally unrelated to suramin, were tested and found to inhibit HDV and HBV infections of PHH. BBG, unlike suramin and PPADS, is known to be more specific for just one purinergic receptor, P2X7. These studies provide the first evidence that purinergic receptor functionality is necessary for virus entry. Furthermore, since P2X7 activation is known to be a major component of inflammatory responses, it is proposed that HDV and HBV attachment to susceptible cells, might also contribute to inflammation in the liver, that is, hepatitis.

Evidence for synergism of the antimicrobial peptide piscidin 2 with antiparasitic and antioomycete drugs

Piscidins are potent, broad-spectrum, host-produced antimicrobial peptides (AMPs) that appear to constitute the most common AMP family in teleost fish. Here, we show that piscidin 2 has potent activity against the water mould Saprolegnia, one of the most important pathogens of freshwater fish. The minimum oomyceticidal concentration (MOC₁₀₀) of piscidin 2 against zoospores of three pathogenic isolates of Saprolegnia ranged from 12.5 to 25.0 μg mL⁻¹. This piscidin concentration is well within levels that have been estimated to be present in at least some fish (1-32.5 μg mL⁻¹). In the presence of either copper or malachite green, two drugs commonly used to treat water moulds, there was evidence for partial synergism (PSYN) with piscidin 2. There was also evidence for PSYN after exposure of the ciliate parasite Tetrahymena pyriformis to piscidin 2 plus copper. Our data provide further evidence that piscidins may be an important host defence against skin and gill pathogens and that the piscidin levels in host tissue might influence the success of drug treatments.

Rapid coomassie blue staining of protein gels

Coomassie brilliant blue R250 (CBR-250) and silver staining are the most widely used methods for the routine visualization of proteins separated by SDS-PAGE. CBR-250 is an organic dye that complexes with basic amino acids, such as arginine, lysine, and histidine, as well as tyrosine. Conventional CBR-250 staining is capable of detecting as little as 30-100 ng of protein, but sensitivity can be improved by performing the staining and destaining at elevated temperatures. The method described in this protocol, which is a modified version of the conventional Coomassie protocol, speeds up the destaining process for faster results with increased sensitivity and is compatible with mass-spectrometry-based methods for identifying proteins.

Microwave-enhanced H2O2-based process for treating aqueous malachite green solutions: intermediates and degradation mechanism

This work was originally performed to compare H(2)O(2)-based degradation of aqueous malachite green (MG) under microwave (MW)-enhanced and conventional heating (CH)-enhanced conditions, with the whole reaction courses traced by UV-vis spectrophotometer. The results showed that the higher discoloration rates of MG were available during MW-enhanced process, implying that the special heating way of MW might be more benefit for the generation of hydroxyl radicals than that of CH. Furthermore, major intermediates were separated and identified by HPLC-ESI-MS and GC-MS techniques. On the basis of 53 intermediates, degradation mechanism was deduced as follows: firstly, N-de-methylation reactions. Secondly, adduction reactions. Thirdly, decomposition of conjugated structure reactions of MG. Fourthly, removal of benzene reactions. Finally, open-ring reactions. Additionally, results revealed that microwave-enhanced H(2)O(2)-based treatment had more advantages, such as higher degradation efficiency, and no removal of catalyst after treatment.

A permeant regulating its permeation pore: inhibition of pannexin 1 channels by ATP

Pannexin 1 forms a large membrane channel that, based on its biophysical properties and its expression pattern, is a prime candidate to represent an ATP release channel. Pannexin 1 channel activity is potentially deleterious for cells as indicated by its involvement in the P2X7 death complex. Here we describe a negative feedback loop controlling pannexin 1 channel activity. ATP, permeant to pannexin 1 channels, was found to inhibit its permeation pathway when applied extracellularly to oocytes expressing pannexin 1 exogenously. ATP analogues, including benzoylbenzoyl-ATP, suramin, and brilliant blue G were even more effective inhibitors of pannexin 1 currents than ATP. These compounds also attenuated the uptake of dyes by erythrocytes, which express pannexin 1. The rank order of the compounds in attenuation of pannexin 1 currents was similar to their binding affinities to the P2X7 receptor, except that receptor agonists and antagonists both were inhibitory to the channel. Mutational analysis identified R75 in pannexin 1 to be critical for ATP inhibition of pannexin 1 currents.

Control of freshwater fish louse Argulus coregoni: a step towards an integrated management strategy

Harmful infections by ectoparasites of the genus Argulus occur repeatedly in freshwater fish farming operations where the management has largely been ineffective. Preventative methods and regular monitoring are rarely applied, so that chemical interventions become necessary. According to the Integrated Pest Management (IPM) approach, a sustainable management or control program for a parasite should be based on knowledge of the ecology of the parasite along with adoption of several prevention and control methods, the application of which is dependent upon the prevailing infection level. The application of multiple management tactics is especially important because parasites can develop resistance to chemical treatments. We took a step towards sustainable management of Argulus populations and tested the effect of several types of treatments on survival of A. coregoni at different stages in its life cycle. Parasite juveniles and adults were highly sensitive to potassium permanganate treatments (0.01 g l(-1)), which lead to 100% mortality, whereas treatments with formalin (0.6 ml l(-1)), sodium chloride (20 g l(-1)) or malachite-green/formalin were not effective. Mechanical treatment by shaking infected fish in a hand net was an effective means of detaching parasites from the fish, and resulted in > 80% decreases in parasite numbers. Compared to eggs in control treatments, both drying over a minimum period of 24 h and formalin treatments (120 ml l(-1)) led to significantly higher mortality of A. coregoni eggs. Other treatments, i.e. drying over a period of 15 h, baths in potassium permanganate (1 g l(-1)) or sodium chloride (50 g l(-1)), did not significantly affect the viability of eggs. Based on the present results and previously published papers, we present an initial framework showing how A. coregoni populations could be managed effectively.

Comparative effects of cationic triarylmethane, phenoxazine and phenothiazine dyes on horse serum butyrylcholinesterase

The kinetic effects of a selection of triarylmethane, phenoxazine and phenothiazine dyes (pararosaniline (PR), malachite green (MG), methyl green (MeG); meldola blue (MB), nile blue (NB), nile red (NR); methylene blue (MethB)) and of ethopropazine on horse serum butyrylcholinesterase were studied spectrophotometrically at 25( degrees )C in 50mM MOPS buffer, pH 8, using butyrylthiocholine as substrate. PR, MeG, MB and ethopropazine acted as linear mixed type inhibitors of the enzyme, with respective K(i) values of 4.5+/-0.50 microM, 0.41+/-0.007 microM, 0.44+/-0.086 microM and 0.050+/-0.0074 microM. MG, NB, MethB and NR caused complex, nonlinear inhibition pointing to cooperative binding at two sites. Intrinsic K' values ( identical with[I](2)(0.5) extrapolated to [S]=0) for MG, NB, NR and MethB were 0.20+/-0.096 microM, 0.0018+/-0.0015 microM, 0.92+/-0.23 microM and 0.23+/-0.08 microM. NB stood out as a potent inhibitor effective at nM levels. Comparison of inhibitory effects on horse and human serum butyrylcholinesterases suggested that the two enzymes must have distinct microstructural features.

Trityl dyes patent blue V and brilliant blue G - clinical relevance and in vitro analysis of the function of the outer blood-retinal barrier

The use of vital dyes during vitrectomy allows easier removal of less recognizable structures like epiretinal membranes or the internal limiting membrane (ILM). In recent years, numerous studies have investigated the use of indocyanine green (ICG), trypan blue (Membrane Blue), triamcinolone, autologous blood and presently trityl dyes such as patent blue V (PBV, Blueron), crystal violet and brilliant blue G (BBG, Brilliant Peel) in chromovitrectomy. Reports on potential risks of these dyes, especially ICG, such as reduced visual acuity, possible visual field defects or alterations of the retinal pigment epithelium (RPE) limited their application. A systematic review of the literature up to July 2007 was performed using Medline (http://www.ncbi.nlm.nih.gov/ PubMed/) where we specifically searched for relevant information regarding the laboratory as well as clinical use of PB and BBG. To evaluate the effect of PB and BBG on the RPE, PB and BBG have been added to an in vitro model of the outer blood-retinal barrier to assess dye-associated barrier properties. Two concentrations of PB (2.4 and 1.2 mg/ml) and BBG (0.25 and 2.4 mg/ml) were investigated. To simulate in vivo conditions of a fluid-filled eye and an air-filled eye the dyes were added either to the culture medium or directly to the RPE cells where they remained for 2.5 min. To determine barrier properties, transepithelial resistance (TER) was measured at 3 days of follow-up. Ultrastructural integrity of RPE cells was evaluated by transmission electron microscopy. Following application of PB, barrier properties in the fluid- as well as in the air-filled eye showed only mild, transient and no significant decrease in TER. BBG did not cause a breakdown of the outer bloodretinal barrier at the concentration of 0.25 mg/ml in the model of the fluid-filled eye. The concentration of 2.4 mg/ml in the model of the fluid-filled eye as well as both concentrations in the model of the air-filled eye showed a minor decrease after 1.5 h, which was no longer observed after 24 h. Transmission electron microscopy did not show any dye-associated ultrastructural alterations to the RPE cells. In clinical use, PB showed only mild staining of epiretinal membranes and moderate staining of the ILM. Although BBG did not stain epiretinal membranes, it represents an appropriate candidate for the future, as BBG has a high affinity for the ILM. The use of trityl dyes in the posterior eye segment seems to be safe concerning damage to the RPE and its barrier function, especially when the dye is applied to the fluid-filled eye.

Mycobacterium smegmatis mc2 155 fbiC and MSMEG_2392 are involved in triphenylmethane dye decolorization and coenzyme F420 biosynthesis

Mycobacteria can tolerate relatively high concentrations of triphenylmethane dyes such as malachite green and methyl violet. To identify mycobacterial genes involved in the decolorization of malachite green, a transposon mutant library of Mycobacterium smegmatis mc2 155 was screened for mutants unable to decolorize this dye. One of the genes identified was MSMEG_5126, an orthologue of Mycobacterium bovis fbiC encoding a 7,8-didemethyl-8-hydroxy-5-deazariboflavin (FO) synthase, which is essential for the biosynthesis of the electron carrier coenzyme F420. The other gene identified was MSMEG_2392, encoding an alanine-rich protein with a DUF121 domain. The minimum inhibitory concentrations (MICs) for malachite green and methyl violet of the six fbiC mutants and two MSMEG_2392 mutants were one-third and one-fifth, respectively, of the MIC of the parent strain M. smegmatis mc2 155. Representative fbiC and MSMEG_2392 mutant strains were also sensitive to oxidative stress caused by the redox-cycling agents plumbagin and menadione, and the sensitivity was reversed in the complemented strains. HPLC analysis of representative fbiC and MSMEG_2392 strains revealed that, while the fbiC mutant lacked both coenzyme F420 and FO, the MSMEG_2392 mutant contained FO but not coenzyme F420. These results indicate that MSMEG_2392 is involved in the biosynthesis of coenzyme F420.

Inhibition of choline oxidase by quinoid dyes

Choline oxidase catalyzes the oxidation of choline to glycine-betaine, with betaine-aldehyde as intermediate and molecular oxygen as primary electron acceptor. This study reports on the inhibitory effects of triarylmethanes (cationic malachite green; neutral leukomalachite green), phenoxazines (cationic, meldola blue and nile blue; neutral nile red) and a structurally-related phenothiazine (methylene blue) on choline oxidase, assayed at 25 degrees C in 50 mM MOPS buffer, pH 7, using choline as substrate. Methylene B acted as a competitive inhibitor with K(i) = 74 +/- 7.2 microM, pointing to the choline-binding site of the enzyme as a target site. Nile B caused noncompetitive inhibition of enzyme activity with K(i) = 20 +/- 4.5 microM. In contrast to methylene B and nile B, malachite G and meldola B caused complex, nonlinear inhibition of choline oxidase, with estimated K(i) values in the micromolar range. The difference in kinetic pattern was ascribed to the differential ability of the dyes to interact (and interfere) with the flavin cofactor, generating different perturbations in the steady-state balance of the catalytic process.

P2X4 is up-regulated in gingival fibroblasts after periodontal surgery

Several studies have shown that surgical detachment of marginal gingiva close to the cervical cementum of molar teeth in a rat mandible is a distinct stimulus for alveolar bone resorption. Recently, we found that P2X4, an ATP-receptor, is significantly up-regulated in marginal gingival cells soon after surgery. We hypothesized that local release of ATP signaling through P2X4 elicits activation of osteoclasts on the alveolar bone surface. In this study, we identified intense immunoreactivity of gingival fibroblasts to P2X4-specific antibodies and a 6.4-fold increase in expression by real-time RT-PCR. Moreover, a single local application, at the time of surgery, of Apyrase (which degrades ATP) or Coomassie Brilliant Blue (an antagonist of purinoreceptors) significantly reduced alveolar bone loss. We propose that ATP flowing from cells after surgery can directly activate P2X4 receptors in the sensor cells of marginal gingiva through Ca(2+) signaling, or by direct activation of osteoclasts on the bone surface.

Protein stains for proteomic applications: which, when, why?

This review recollects literature data on sensitivity and dynamic range for the most commonly used colorimetric and fluorescent dyes for general protein staining, and summarizes procedures for the most common PTM-specific detection methods. It also compiles some important points to be considered in imaging and evaluation. In addition to theoretical considerations, examples are provided to illustrate differential staining of specific proteins with different detection methods. This includes a large body of original data on the comparative evaluation of several pre- and post-electrophoresis stains used in parallel on a single specimen, horse serum run in 2-DE (IPG-DALT). A number of proteins/protein spots are found to be over- or under-revealed with some of the staining procedures.

Bactericidal effect of malachite green and red laser on Actinobacillus actinomycetemcomitans

The aim of this study was to investigate the ability of malachite green (MG) combined with a low-power red laser to kill Actinobacillus actinomycetemcomitans and to investigate MG photodegradation after photodynamic therapy (PDT) by optical absorption spectroscopy. The etiology of periodontal disease is that microorganisms form a bacterial biofilm on the surface of the teeth. It is an infectious disease and A. actinomycetemcomitans is considered an important agent in biofilm ecology. Instead of using antibiotics, PDT is an alternative approach to eradicate bacteria. Cultures of A. actinomycetemcomitans were exposed to a 30 mW diode red laser, in the presence or absence of MG. A group of cultures was treated in dark conditions in the presence of MG (0.01% w/v) for 5 min. In the presence of MG, two exposure times for laser irradiation were used: t=3 min (energy dose=5.4 J/cm(2)), and t=5 min (energy dose=9 J/cm(2)). The samples were diluted and bacterial colonies were counted and converted into colony forming units. Absorption spectra of the bacterial suspensions, MG, MG-stained bacterial suspensions, and photosensitized bacterial suspensions were obtained. A. actinomycetemcomitans can be photoinactivated by a red laser in the presence of MG. Significant differences were observed between the two energy doses used (p<0.05). Red laser alone and MG alone were not able to kill bacteria. Optical absorption showed that MG is photobleached after irradiation. These results indicate that A. actinomycetemcomitans can be photosensitized by red laser combined with MG and that the dye is photodegraded following irradiation.

Decreased Phosphoactive ERKs and JNKs in Malachite-Green-Transformed Syrian Hamster Embryo Fibroblasts Are Associated with Increased Phosphoactive p38 Kinase: Possible Therapeutic Importance

BACKGROUND

Malachite green (MG), consisting of green crystals with a metallic lustre, is highly soluble in water, cytotoxic to various mammalian cells and also acts as a liver tumor promoter. In view of its industrial importance and possible exposure of human beings, MG poses a potential environmental health hazard. We have earlier reported the malignant transformation of Syrian hamster embryo (SHE) cells by MG.

METHODS

Cell transformation assays were carried out as described in the literature. Western blotting and flow cytometry were carried out by standard methods.

RESULTS

In this study, we have studied the role of all three isoforms of mitogen-activated protein (MAP) kinases, i.e. extracellular regulated kinases (ERKs), Jun N-terminal kinases (JNKs) and p38 kinase in the MG-transformed SHE fibroblasts compared to controls. Our results showed that transformed cells were associated with decreased expression of ERKs and JNKs as evidenced by Western blotting studies. However, the p38 MAP kinase was found to be upregulated. Flow cytometric DNA histogram analysis indicated an increase in the expression of S phase cells in the transformed cell line as compared to their control counterparts.

CONCLUSIONS

The present studies indicate that decreased phosphoactive ERKs and JNKs and increased phosphoactive p38 kinase are associated with increased S phase cells during transformation of SHE cells by MG.

Elevated phosphorylation of Chk1 and decreased phosphorylation of Chk2 are associated with abrogation of G2/M checkpoint control during transformation of Syrian hamster embryo (SHE) cells by Malachite green

Malachite green (MG), consisting of green crystals with a metallic lustre, is highly soluble in water, cytotoxic to various mammalian cells and also acts as a liver tumor promoter. In view of its industrial importance and possible exposure to human beings, MG poses a potential environmental health hazard. We have earlier reported the malignant transformation of Syrian hamster embryo (SHE) cells in primary culture by MG. In this study, we have studied the ability of MG to cause DNA damage, cell cycle arrest in mimosine synchronised and the possible roles of Chk1, Chk2, Cdc2, Cdc25C, 14-3-3 and Cyclin B1 in control and MG transformed SHE cells in order to understand the differential mechanisms associated with G2/M checkpoint control. Exposure of MG to control and transformed cells causes DNA damage. Flow cytometric analysis of mimosine synchronised cells when exposed to MG showed an increase of G2/M phase in control cells whereas no such accumulation of cells at the G2/M phase was observed in response to MG in transformed cells. Western blots of phosphoactive forms of Chk1 and Chk2 cells showed opposing levels. Control cells treated with MG showed a decrease in Chk1 and increase in Chk2, whereas the transformed cells treated with MG showed an increase in Chk1 and decrease in Chk2. Also a decrease in Cdc25C, 14-3-3 and Cyclin B1 was observed in MG treated transformed cells, whereas MG treated control cells showed elevated levels. Stabilization of the proteins seems to be the possible mechanism. The present study indicates elevated phosphorylation of Chk1 and decreased phosphorylation of Chk2 and decreased levels of Cyclin B1 are the critical changes associated with abrogation of G2/M checkpoint control during transformation of SHE cells by MG.

Effect of fast green dye on some biophysical properties of thymocytes and splenocytes of albino mice

Although fast green (FG) is widely used as food colorant by the cosmetics and drug industries, there is no evidence about whether FG affects leukocytes. The aim was to investigate the effect of FG on leukocytes. Male albino mice were subdivided into five equal groups: four of them were given 125, 250, 375 and 500 mg kg(-1) bw day(-1) FG in drinking water for 44 days. The fifth (control group) was given pure water only. During the experimental period changes in body weight, lymphoid organs weight (absolute and relative) as well as the total count and viability of lymphoid cells for the treated groups showed that FG was an immunotoxic agent. The structural effects induced by FG on thymocytes and splenocytes were investigated through measurements of their dielectric spectra in the frequency range 20-100,000 Hz. The estimated dielectric parameters of the treated groups reflected the changes occurring to lymphocytes by FG administration and indicated that FG dye is an immunotoxic agent. It is shown that the dielectric methodology can be used for the identification of lymphocyte modification induced by food colorants.

Decavanadate, a P2X receptor antagonist, and its use to study ligand interactions with P2X7 receptors

In this study we have studied decavanadate effects at P2X receptors. Decavanadate competitively blocked 2'- and 3'-O-(4benzoylbenzoyl) ATP (BzATP) stimulated ethidium accumulation in HEK293 cells expressing human recombinant P2X7 receptors (pK(B) 7.5). The effects of decavanadate were rapid (minutes) in both onset and offset and contrasted with the much slower kinetics of pyridoxal 5-phosphate (P5P), Coomassie brilliant blue (CBB) and 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN62). Decavanadate competitively blocked the slowly reversible, or irreversible, blockade of the P2X7 receptor produced by P5P and oxidised ATP suggesting competition for a common binding site. However, the interaction between decavanadate and KN62 was non-competitive. Decavanadate also blocked P2X2 and P2X4 receptors but with slightly lower potency. These data demonstrate that decavanadate is the first reversible and competitive antagonist of the P2X7 receptor and is a useful tool for studying the mechanism of interaction of ligands with the P2X7 receptor.

Protein isolation and second-dimension electrophoretic separation

Protocols for the proteome analysis of Arabidopsis tissues based on 2 D gel electrophoresis are given for leaves and roots as well as for seeds. The protocols contain a detailed description of the sample preparation step and of the solubilization of proteins. We then describe our protocols for the isoelectric focusing, the transfer of the strips from the first to the second dimension, SDS-PAGE as the second dimension of electrophoretic separation, staining of the gels using colloidal Coomassie blue, and finally drying of the gels between cellophane sheets. Notes contain additional background information on critical steps. Our protocols allow the analysis of leaves, roots, or seeds from different Arabidopsis ecotypes, from mutants or from plants subjected to various environmental conditions.

P2 receptor blockade attenuates fever and cytokine responses induced by lipopolysaccharide in rats

Adenosine 5'-triphosphate (ATP) has been shown to induce release of cytokines implicated in fever, including interleukin(IL)-1beta, IL-6, and tumour necrosis factor-alpha (TNF-alpha). The role of ATP-mediated purinergic signalling in fever and cytokine release during systemic inflammation was investigated by studying the effects of P2 receptor antagonists suramin, pyridoxal-5'-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS), and Brilliant Blue G (BBG) on changes in body temperature and the increases in plasma levels of IL-1beta, IL-6, and TNFalpha induced by bacterial lipopolysaccharide (LPS) in rats. LPS (Escherichia coli; 50 microg kg(-1))-induced febrile response was attenuated by suramin (25 mg kg(-1) and 100 mg kg(-1)), PPADS (25 mg kg(-1)), and a more selective P2X(7) receptor antagonist BBG (100 mg kg(-1)) injected intraperitoneally before the induction of fever. The increase in plasma concentrations of IL-1beta and IL-6, measured 1 h after LPS treatment, was reduced by PPADS (25 mg kg(-1)) and BBG (100 mg kg(-1)). LPS-induced increase in plasma TNF-alpha concentration was also markedly attenuated by BBG (100 mg kg(-1)), but not by PPADS (25 mg kg(-1)). These data indicate that purinergic signalling plays an important role in the mechanisms responsible for the LPS-induced febrile response and increases in the levels of circulating cytokines. We suggest that ATP acting via P2X(7) receptors induces release of pyrogenic cytokines to mediate fever during systemic inflammation.

Retinal tolerance to dyes

BACKGROUND

Dye solutions for intraoperative staining of epiretinal membranes and the internal limiting membrane improve the visualisation of these thin structures and facilitate their removal. In the present study the authors investigated the effects of indocyanine green 0.05%, trypan blue 0.15%, and patent blue 0.48% on bovine retinal function.

METHODS

Bovine retina preparations were perfused with a standard solution and the electroretinogram (ERG) was recorded repeatedly. After recording of stable ERG amplitudes the nutrient solution was substituted by one of the dye solutions. The duration of retinal exposure to a dye solution was varied between 10 seconds and 2 minutes. Thereupon, the preparation was reperfused with standard solution for at least 115 minutes. The percentage of b-wave reduction after exposition was calculated.

RESULTS

Reductions of the b-wave amplitude were found for each dye solution tested. The effects after application of patent blue and indocyanine green were completely reversible within the recovery time for an exposure period of 60 and 30 seconds, respectively. The application of trypan blue lead to a loss of the b-wave when the retina was exposed for 15 seconds or longer. This effect was only partly reversible within the recovery time.

CONCLUSION

The ERG showed toxic effects of trypan blue after a short period of retinal exposure. The intraocular application of trypan blue should be limited to selected cases. However, intraocular application of indocyanine green and patent blue in a sufficient concentration and taking account of a short period of retinal exposure seems possible.

Effects of malachite green (MG) and its major metabolite, leucomalachite green (LMG), in two human cell lines

Malachite green (MG) is still illegally used as a fungicide in aquaculture. In fish it is absorbed and metabolised to its major reduced metabolite, leucomalachite green (LMG). This latter represents the main residue found in fish tissues and may persist for several months. Since MG, suspected to act as a tumour promoter in vitro and in vivo, might be also present as a residue in fish, the present study was undertaken to ascertain the in vitro toxicity of both compounds in two human tumour cell lines (Caco-2 and HEp-2). After 24h incubation with MG, significant decreases of cell viability, measured by neutral red uptake (NRU) or total protein content (TPC) as well as proliferation capability (colony-forming ability, CFA) were noticed in HEp-2 cells; the mean IC(50) value was about 2 microM. As regards the differentiated Caco-2 cells, MG caused a dose-related significant cytotoxicity, measured either by MTT test, the LDH leakage or NRU, with a mean IC(50) value of about 15 microM. By contrast, LMG disclosed, in both cell lines, a lower cytotoxicity compared to MG. These results also show that HEp-2 cells are more sensitive than intestinal cells to the toxic action of both compounds.

In vitro differentiation of mouse embryonic stem cells: enrichment of endodermal cells in the embryoid body

Embryonic stem (ES) cells have the potential to differentiate into all three germ layers, providing new perspectives not only for embryonic development but also for the application in cell replacement therapies. Even though the formation of an embryoid body (EB) in a suspension culture has been the most popular method to differentiate ES cells into a wide range of cells, not much is known about the characteristics of EB cells. To this end, we investigated the process of EB formation in the suspension culture of ES cells at weekly intervals for up to 6 weeks. We observed that the central apoptotic area is most active in the first week of EB formation and that the cell adhesion molecules, except beta-catenin, are highly expressed throughout the examination period. The sequential expression of endodermal genes in EBs during the 6-week culture correlated closely with that of normal embryo development. The outer surface of EBs stained positive for alpha-fetoprotein and GATA-4. When isolated from the 2-week-old EB by trypsin treatment, these endodermal lineage cells matured in vitro into hepatocytes upon stimulation with various hepatotrophic factors. In conclusion, our results demonstrate that endodermal cells can be retrieved from EBs and matured into specific cell types, opening new therapeutic usage of these in vitro differentiated cells in the cell replacement therapy of various diseases.

Inhibition of human plasma cholinesterase by malachite green and related triarylmethane dyes: Mechanistic implications

The inhibitory effects of the cationic triarylmethane (TAM+) dyes, pararosaniline (PR+), malachite green (MG+), and methyl green (MeG+) on human plasma cholinesterase (BChE) were studied at 25 degrees C in 100 mM Mops, pH 8.0, with butyrylthiocholine as substrate. PR+ and MG+ caused linear mixed inhibition of enzyme activity. The respective inhibitory parameters were K(i) = 1.9 +/- 0.23 microM, alpha = 13 +/- 48, beta = 0 and K(i) = 0.28 +/- 0.037 microM, alpha = 23 +/- 7.4, beta = 0. MeG+ acted as a competitive inhibitor with K(i) = 0.12 +/- 0.017 microM (alpha, infinity, beta, not applicable). The K(i) values were within the same range reported for a number of ChE inhibitors including propidium ion, donepezil, and the phenothiazines, suggesting that TAM+s are active site ligands. On the other hand, the alpha values failed to correlate with values previously reported for a number of ChE inhibitors. It appears that mixed inhibition is the combined result of more than one type of binding and S-I interference. The impact of ligands at the choline-specific and peripheral anionic sites (or, possibly, accessory structural domains) on BChE activity needs to be studied in further detail.

Effect on oximetry of dyes used for sentinel lymph node biopsy

HYPOTHESIS

There are differences between readings of peripheral blood oxygen saturation when the effect on saturation values of methylene blue is compared with that of isosulfan blue when used in sentinel lymph node biopsy in patients with breast cancer.

DESIGN

Prospective randomized study.

SETTING

University tertiary care center.

PATIENTS

Thirty-two women undergoing surgery for breast cancer using sentinel lymph node biopsy.

INTERVENTIONS

Sentinel lymph node biopsy using methylene blue (16 patients) and isosulfan blue (16 patients); there was also a control group of 6 surgical patients in whom dyes were not used.

MAIN OUTCOME MEASURES

Peripheral saturation of blood using pulse oximetry, oxygen saturation by blood-gas analysis, partial oxygen pressure by blood-gas analysis, and plasma dye levels, recorded before dye injection and 15, 30, and 60 minutes afterward.

RESULTS

The 2 dyes interfered with the peripheral saturation reading, but only isosulfan blue showed significant differences. The differences in blood-gas analysis values between the 2 groups and with regard to the controls were not significant.

CONCLUSIONS

Methylene blue interferes less than isosulfan blue in the peripheral saturation reading. Desaturation is factitious in both cases, and does not correspond to alterations in blood-gas analysis values.

Problems caused by high concentration of ATP on activation of the P2X7 receptor in bone marrow cells loaded with the Ca2+ fluorophore fura-2

Fura-2 is one of the most used fluorophore for measuring intracellular calcium concentration ([Ca2+]i). In mouse bone marrow cell suspensions ATP produces a biphasic effect: till 1 mM, ATP produces increases in [Ca2+]i; from 1 mM on an increase is observed, that is followed by the decrease in the 340/380 nm ratio (R340/380). At high ATP (4 mM) concentration fura-2 leaked from loaded bone marrow cell suspensions. We observed that ATP decreases fluorescence in the absorption and excitation spectra of fura-2, consequently the emitted one is decreased including the isobestic point (360 nm). ATP analogs: BzATP, ATPyS and UTP, but not alphabetaATP, ADP or AMP, promote decrease of fluorescence in the isobestic point of fura-2. The physical/chemical process that reduces the absorption and excitation of fura-2 by ATP is unknown. The P2X7 inhibitors, Mg2+ (5 mM), OxATP (300 microM) and Brilliant Blue (100 nM), blocked the efflux of fura-2 and ATP-induced R340/380 decrease. The J774 cell line and mononuclear cells with a higher expression of P2X7 receptors show the same decrease in R340/380 as that induced by ATP. In the HL-60 cell line, myeloid cells and erythroblasts extracted from bone marrow, such effect does not occur. It is concluded that the use of the fluorescent Ca2+ indicator fura-2 does not allow the correct measurement of [Ca2+]i in these cells in the presence of a higher concentration of ATP which activated the P2X7 receptor.

Differential protein composition of bovine whey: a comparison of whey from healthy animals and from those with clinical mastitis

During clinical mastitis in dairy cows, the quantity of milk produced decreases and the composition of the milk is altered. As the severity of inflammation associated with the disease increases, the chemical composition of milk approaches that of blood as a consequence of increased permeability of the blood mammary barrier, or de novo intramammary synthesis, as has been suggested for mammary associated serum amyloid A3. A better understanding of these events may provide new approaches for the diagnosis and treatment of mastitis. The objective of this study was to document the changes in the protein composition of milk during clinical mastitis using a proteomic approach, with the objective of identifying new diagnostic markers of mastitis. Whey from dairy cows with clinical mastitis was compared to whey from healthy animals by two-dimensional gel electrophoresis (2-DE) with colloidal Coomassie staining and matrix-assisted desorption/ionization mass spectrometry. Increases in the concentrations of proteins of blood serum origin, including serotransferrin and albumin, were identified in mastitic whey compared to normal whey, while concentrations of the major whey proteins alpha-lactalbumin and beta-lactoglobulin were reduced in mastitic whey. Mass spectrometry subsequently confirmed the location of albumin, alpha-lactalbumin and beta-lactoglobulin on the 2-DE gels at M(r)/pI of 69 294/5.8, 14 200/4.5 and 19 883/4.9 respectively.

Proteome reference maps of Medicago truncatula embryogenic cell cultures generated from single protoplasts

Using a combination of two-dimensional gel electrophoresis (2-DE) protein mapping and mass spectrometry (MS) analysis, we have established proteome reference maps of Medicago truncatula embryogenic tissue culture cells. The cultures were generated from single protoplasts, which provided a relatively homogeneous cell population. We used these to analyze protein expression at the globular stages of somatic embryogenesis, which is the earliest morphogenetic embryonic stage. Over 3000 proteins could reproducibly be resolved over a pI range of 4-11. Three hundred and twelve protein spots were extracted from colloidal Coomassie Blue-stained 2-DE gels and analyzed by matrix-assisted laser desorption/ionization-time of flight MS analysis and tandem MS sequencing. This enabled the identification of 169 protein spots representing 128 unique gene products using a publicly available expressed sequence tag database and the MASCOT search engine. These reference maps will be valuable for the investigation of the molecular events which occur during somatic embryogenesis in M. truncatula. The proteome reference maps and supplementary materials will be available and updated for public access at http://semele.anu.edu.au/.

New Functions of the Thylakoid Membrane Proteome of Arabidopsis thaliana Revealed by a Simple, Fast, and Versatile Fractionation Strategy

Identification of membrane proteomes remains challenging. Here, we present a simple, fast, and scalable off-line procedure based on three-phase partitioning with butanol to fractionate membrane proteomes in combination with both in-gel and in-solution digestions and mass spectrometry. This should help to further accelerate the field of membrane proteomics. Using this new strategy, we analyzed the salt-stripped thylakoid membrane of chloroplasts of Arabidopsis thaliana. 242 proteins were identified, at least 40% of which are integral membrane proteins. The functions of 86 proteins are unknown; these include proteins with TPR, PPR, rhodanese, and DnaJ domains. These proteins were combined with all known thylakoid proteins and chloroplast (associated) envelope proteins, collected from primary literature, resulting in 714 non-redundant proteins. They were assigned to functional categories using a classification developed for MapMan (Thimm, O., Blasing, O., Gibon, Y., Nagel, A., Meyer, S., Kruger, P., Selbig, J., Muller, L. A., Rhee, S. Y., and Stitt, M. (2004) Plant J. 37, 914-939), updated with information from primary literature. The analysis elucidated the likely location of many membrane proteins, including 190 proteins of unknown function, holding the key to better understanding the two membrane systems. The three-phase partitioning procedure added a new level of dynamic resolution to the known thylakoid proteome. An automated strategy was developed to track possible ambiguous identifications to more than one gene model or family member. Mass spectrometry search results, ambiguities, and functional classifications can be searched via the Plastid Proteome Database.

A PTEN-like Phosphatase with a Novel Substrate Specificity

We show that a novel PTEN-like phosphatase (PLIP) exhibits a unique preference for phosphatidylinositol 5-phosphate (PI(5)P) as a substrate in vitro. PI(5)P is the least characterized member of the phosphoinositide (PI) family of lipid signaling molecules. Recent studies suggest a role for PI(5)P in a variety of cellular events, such as tumor suppression, and in response to bacterial invasion. Determining the means by which PI(5)P levels are regulated is therefore key to understanding these cellular processes. PLIP is highly enriched in testis tissue and, similar to other PI phosphatases, exhibits poor activity against several proteinaceous substrates. Despite a recent report suggesting a role for PI(5)P in the regulation of Akt, the overexpression of wild-type or catalytically inactive PLIP in Chinese hamster ovary-insulin receptor cells or a dsRNA-mediated knockdown of PLIP mRNA levels in Drosophila S2 cells does not alter Akt activity or phosphorylation. The unique in vitro catalytic activity and detailed biochemical and kinetic analyses reported here will be of great value in our continued efforts to identify in vivo substrate(s) for this highly conserved phosphatase.

Assessing factors for reliable quantitative proteomics based on two-dimensional gel electrophoresis

We statistically analysed various factors to get accurate estimates of protein quantities from two-dimensional gels. Yeast proteins were labelled with (35)S or stained with Coomassie Brilliant Blue G-250, and spots were automatically quantified with software packages Kepler, ImageQuaNT, Melanie 3.0 and Progenesis. The different software packages proved to have very similar performances. With (35)S-labelled actin spot as a reference, we studied the staining efficiency of colloidal Coomassie blue as a function of amino acid composition of the protein, and derived an equation to estimate the number of molecules per cell from blue-stained proteins. Absolute quantification of most glycolytic enzymes was carried out in two yeast strains.