A pathogenic role for histone H3 copper reductase activity in a yeast model of Friedreich's ataxia

Disruptions to iron-sulfur (Fe-S) clusters, essential cofactors for a broad range of proteins, cause widespread cellular defects resulting in human disease. A source of damage to Fe-S clusters is cuprous (Cu1+) ions. Since histone H3 enzymatically produces Cu1+ for copper-dependent functions, we asked whether this activity could become detrimental to Fe-S clusters. Here, we report that histone H3–mediated Cu1+ toxicity is a major determinant of cellular functional pool of Fe-S clusters. Inadequate Fe-S cluster supply, due to diminished assembly as occurs in Friedreich’s ataxia or defective distribution, causes severe metabolic and growth defects in Saccharomyces cerevisiae. Decreasing Cu1+ abundance, through attenuation of histone cupric reductase activity or depletion of total cellular copper, restored Fe-S cluster–dependent metabolism and growth. Our findings reveal an interplay between chromatin and mitochondria in Fe-S cluster homeostasis and a potential pathogenic role for histone enzyme activity and Cu1+ in diseases with Fe-S cluster dysfunction.

The histone H3-H4 tetramer is a copper reductase enzyme

Eukaryotic histone H3-H4 tetramers contain a putative copper (Cu²⁺) binding site at the H3-H3' dimerization interface with unknown function. The coincident emergence of eukaryotes with global oxygenation, which challenged cellular copper utilization, raised the possibility that histones may function in cellular copper homeostasis. We report that the recombinant Xenopus laevis H3-H4 tetramer is an oxidoreductase enzyme that binds Cu²⁺ and catalyzes its reduction to Cu¹⁺ in vitro. Loss- and gain-of-function mutations of the putative active site residues correspondingly altered copper binding and the enzymatic activity, as well as intracellular Cu¹⁺ abundance and copper-dependent mitochondrial respiration and Sod1 function in the yeast Saccharomyces cerevisiae The histone H3-H4 tetramer, therefore, has a role other than chromatin compaction or epigenetic regulation and generates biousable Cu¹⁺ ions in eukaryotes.

The influence of restorative material and glass fiber posts on fracture strength of endodontically treated premolars after extensive structure loss

OBJECTIVE

The aim of this in vitro study was to investigate the fracture strength and cuspal deflection of endodontically treated premolars restored using different composite resins along with or without fiber post application.

MATERIALS AND METHOD

Eighty intact premolars were randomly divided into eight groups (n = 10); CO group: intact teeth (control), OPR group: mesio-occlusal-distal-palatal (MODP) preparation (OPR) + endodontic treatment (ET), TC group: MODP preparation + ET + Tetric N-Ceram, TB group: MODP preparation + ET + Tetric EvoCeram Bulk Fill, SO group: MODP preparation + ET + SonicFill 2, TC-P group: MODP preparation + ET + Hahnenkratt glass fiber post + Tetric N-Ceram, TB-P group: MODP preparation + ET + Hahnenkratt glass fiber + Tetric EvoCeram Bulk Fill, and SO-P Group: MODP preparation + ET + Hahnenkratt glass fiber post + SonicFill 2. After thermocycling, specimens were subjected to a compressive load until fracture. Data were analyzed using analysis of variance and Tukey tests (P < 0.05).

RESULTS

The mean fracture strength of groups which received post treatment showed similar fracture strength values [TC-P (931.6 ± 97.9), TB-P (882.0 ± 59.7), SO-P (862.0 ± 143.0) (P > 0.05)] and was significantly higher than OPR (530.6 ± 41.7), TC (841.2 ± 93.1), TB (774.5 ± 101.8), and SO (735.0 ± 178.01) groups (P < 0.05). No significant difference was detected among groups considering cuspal deflection (P > 0.05). The fiber post insertion resulted in more unfavorable fractures.

CONCLUSION

Endodontically treated teeth restored with fiber post and bulk-fill or conventional composite resins demonstrated fracture strength values similar to intact teeth.

Histone deacetylase inhibitors provoke a tumor supportive phenotype in pancreatic cancer associated fibroblasts

Although histone deacetylase inhibitors (HDACi) are a promising class of anti-cancer drugs, thus far, they have been unsuccessful in early phase clinical trials for pancreatic ductal adenocarcinoma (PDAC). One potential reason for their poor efficacy is the tumor stroma, where cancer-associated fibroblasts (CAFs) are a prominent cell type and a source of resistance to cancer therapies. Here, we demonstrate that stromal fibroblasts contribute to the poor efficacy of HDACi's in PDAC. HDACi-treated fibroblasts show increased biological aggressiveness and are characterized by increased secretion of pro-inflammatory tumor-supportive cytokines and chemokines. We find that HDAC2 binds to the enhancer and promoter regions of pro-inflammatory genes specifically in CAFs and in silico analysis identified AP-1 to be the most frequently associated transcription factor bound in these regions. Pharmacologic inhibition of pathways upstream of AP-1 suppresses the HDACi-induced inflammatory gene expression and tumor-supportive responses in fibroblasts. Our findings demonstrate that the combination of HDACi's with chemical inhibitors of the AP-1 signaling pathway attenuate the inflammatory phenotype of fibroblasts and may improve the efficacy of HDACi in PDAC and, potentially, in other solid tumors rich in stroma.

Endoplasmic reticulum-mitochondria junction is required for iron homeostasis

The endoplasmic reticulum (ER)-mitochondria encounter structure (ERMES) is a protein complex that physically tethers the two organelles to each other and creates the physical basis for communication between them. ERMES functions in lipid exchange between the ER and mitochondria, protein import into mitochondria, and maintenance of mitochondrial morphology and genome. Here, we report that ERMES is also required for iron homeostasis. Loss of ERMES components activates an Aft1-dependent iron deficiency response even in iron-replete conditions, leading to accumulation of excess iron inside the cell. This function is independent of known ERMES roles in calcium regulation, phospholipid biosynthesis, or effects on mitochondrial morphology. A mutation in the vacuolar protein sorting 13 (VPS13) gene that rescues the glycolytic phenotype of ERMES mutants suppresses the iron deficiency response and iron accumulation. Our findings reveal that proper communication between the ER and mitochondria is required for appropriate maintenance of cellular iron levels.

Exploitation of EP300 and CREBBP Lysine Acetyltransferases by Cancer

p300 and CREB-binding protein (CBP), two homologous lysine acetyltransferases in metazoans, have a myriad of cellular functions. They exert their influence mainly through their roles as transcriptional regulators but also via nontranscriptional effects inside and outside of the nucleus on processes such as DNA replication and metabolism. The versatility of p300/CBP as molecular tools has led to their exploitation by viral oncogenes for cellular transformation and by cancer cells to achieve and maintain an oncogenic phenotype. How cancer cells use p300/CBP in their favor varies depending on the cellular context and is evident by the growing list of loss- and gain-of-function genetic alterations in p300 and CBP in solid tumors and hematological malignancies. Here, we discuss the biological functions of p300/CBP and how disruption of these functions by mutations and alterations in expression or subcellular localization contributes to the cancer phenotype.

Antitumor effects of the investigational selective MEK inhibitor TAK733 against cutaneous and uveal melanoma cell lines

BACKGROUND

TAK733 is a novel allosteric, non-ATP-binding, inhibitor of the BRAF substrates MEK-1/2.

METHODS

The growth inhibitory effects of TAK733 were assessed in a panel of 27 cutaneous and five uveal melanoma cell lines genotyped for driver oncogenic mutations. Flow cytometry, Western blots and metabolic tracer uptake assays were used to characterize the changes induced by exposure to TAK733.

RESULTS

Fourteen cutaneous melanoma cell lines with different driver mutations were sensitive to the antiproliferative effects of TAK733, with a higher proportion of BRAFV600E mutant cell lines being highly sensitive with IC50s below 1 nM. The five uveal melanoma cell lines had GNAQ or GNA11 mutations and were either moderately or highly sensitive to TAK733. The tested cell lines wild type for NRAS, BRAF, GNAQ and GNA11 driver mutations were moderately to highly resistant to TAK733. TAK733 led to a decrease in pERK and G1 arrest in most of these melanoma cell lines regardless of their origin, driver oncogenic mutations and in vitro sensitivity to TAK733. MEK inhibition resulted in increase in pMEK more prominently in NRASQ61L mutant and GNAQ mutant cell lines than in BRAFV600E mutant cell lines. Uptake of the metabolic tracers FDG and FLT was inhibited by TAK733 in a manner that closely paralleled the in vitro sensitivity assays.

CONCLUSIONS

The MEK inhibitor TAK733 has antitumor properties in melanoma cell lines with different oncogenic mutations and these effects could be detectable by differential metabolic tracer uptake.

Reversing melanoma cross-resistance to BRAF and MEK inhibitors by co-targeting the AKT/mTOR pathway

Background

The sustained clinical activity of the BRAF inhibitor vemurafenib (PLX4032/RG7204) in patients with BRAF^V600 mutant melanoma is limited primarily by the development of acquired resistance leading to tumor progression. Clinical trials are in progress using MEK inhibitors following disease progression in patients receiving BRAF inhibitors. However, the PI3K/AKT pathway can also induce resistance to the inhibitors of MAPK pathway.

Methodology/Principal Findings

The sensitivity to vemurafenib or the MEK inhibitor AZD6244 was tested in sensitive and resistant human melanoma cell lines exploring differences in activation-associated phosphorylation levels of major signaling molecules, leading to the testing of co-inhibition of the AKT/mTOR pathway genetically and pharmacologically. There was a high degree of cross-resistance to vemurafenib and AZD6244, except in two vemurafenib-resistant cell lines that acquired a secondary mutation in NRAS. In other cell lines, acquired resistance to both drugs was associated with persistence or increase in activity of AKT pathway. siRNA-mediated gene silencing and combination therapy with an AKT inhibitor or rapamycin partially or completely reversed the resistance.

Conclusions/Significance

Primary and acquired resistance to vemurafenib in these in vitro models results in frequent cross resistance to MEK inhibitors, except when the resistance is the result of a secondary NRAS mutation. Resistance to BRAF or MEK inhibitors is associated with the induction or persistence of activity within the AKT pathway in the presence of these drugs. This resistance can be potentially reversed by the combination of a RAF or MEK inhibitor with an AKT or mTOR inhibitor. These combinations should be available for clinical testing in patients progressing on BRAF inhibitors.

First Report of Chickpea chlorotic stunt virus Infecting Legume Crops in Tunisia

During a survey of legume crops in the northeast and northwest regions of Tunisia in April 2010, plants showing yellowing, reddening, and stunting symptoms were observed. A total of 281 symptomatic samples were collected: 142 plants from 10 chickpea (Cicer arietinum L.) fields, 84 plants from six faba bean (Vicia faba L.) fields, and 55 plants from six pea (Pisum sativum L.) fields. All samples were tested by the tissue-blot immunoassay procedure with the following monoclonal antibodies (MAbs): a broad-spectrum legume-luteovirus MAb (5G4), Faba bean necrotic yellows virus (FBNYV; genus Nanovirus, family Nanovirudae) (3-2E9; provided by J. Vetten, BBA, Braunschweig, Germany), Beet western yellows virus (BWYV; genus Polerovirus, family Luteoviridae) (A5977; Agdia, Elkhart, IN), Bean leafroll virus (BLRV; genus Luteovirus, family Luteoviridae) (4B10), Soybean dwarf virus (SbDV; genus Luteovirus, family Luteoviridae) (ATCC PVAS-650; American Type Culture Collection ATCC, Rockville, MD,), and a mixture of three MAbs (5-2B8, -3D5, and -5B8) to a Syrian isolate of Chickpea chlorotic stunt virus (CpCSV) (1). Serological tests showed that CpCSV was detected in 121 samples (43.06%) (62 chickpea, 57 faba bean, and 2 pea), followed by FBNYV (detected in three faba bean and three pea), BWYV (detected in three chickpea and one faba bean), and BLRV (detected in one pea sample). FBNYV, BLRV, and BWYV have been previously detected in faba bean and chickpea in Tunisia (4), but to our knowledge, this is the first report of CpCSV affecting legumes in Tunisia, which was found in seven chickpea, seven faba bean, and two pea fields. CpCSV has been reported to naturally infect legume crops such as chickpea, lentil, field pea, and faba bean as well as some leguminous weeds and a few wild non-legume plants species in many countries in West Asia and North Africa and causes economic losses on chickpea in Eritrea, Ethiopia, and Syria (1-3). Serological results of CpCSV was confirmed in four (two pea, one faba bean, and one chickpea) samples by reverse transcription (RT)-PCR using CpCSV specific primers (F:5'-TAGGCGTACTGTTCAGCGGG-3' and R:5'-TCCTTTGTCCATTCGAGGTGA-3') (3), which produced an amplicon of expected size (413 bp). No amplification was observed from healthy plant extracts. Sequence analysis revealed that the four Tunisian isolates (TuV 258-201 collected from faba bean [GenBank Accession No. HQ199310], TuC 215-201 collected from chickpea [HQ199307], and TuP 163-201 [HQ199308] and TuP 166-201 collected from pea [HQ199309]) were most similar to each other with a high sequence identity (99%) and clustered with isolates of CpCSV from Syria (GenBank Accession No. EU541270), Egypt (EU541269), and Morocco (EU541267), to which they were most closely related (98%). The Tunisian isolates also showed high sequence identity (96%) in the coat protein region with Ethiopian (GenBank Accession No. EU541257) and Sudanese (EU541263) isolates. However, all isolates are distinct from BWYV, BLRV, and SbDV (less than 70% sequence identity). Since CpCSV is transmitted by aphids only, additional studies are needed to identify the host range of the virus and the efficient aphid vectors to better understand the epidemiology of this virus under Tunisian conditions References: (1) A. D. Abraham et al. Arch.Virol. 154:791; 2009. (2) N. Y. Asaad et al. J. Phytopathol. 157:756, 2009. (3) S. G. Kumari et al. Phytopathol. Mediterr. 47:42, 2008. (4) A. Najar et al. Phytopathol. Mediterr. 39:423, 2000.

Combination therapy with vemurafenib (PLX4032/RG7204) and metformin in melanoma cell lines with distinct driver mutations

Background

A molecular linkage between the MAPK and the LKB1-AMPK energy sensor pathways suggests that combined MAPK oncogene inhibition and metabolic modulation of AMPK would be more effective than either manipulation alone in melanoma cell lines.

Materials and methods

The combination of the BRAF inhibitor vemurafenib (formerly PLX4032) and metformin were tested against a panel of human melanoma cell lines with defined BRAF and NRAS mutations for effects on viability, cell cycle and apoptosis. Signaling molecules in the MAPK, PI3K-AKT and LKB1-AMPK pathways were studied by Western blot.

Results

Single agent metformin inhibited proliferation in 12 out of 19 cell lines irrespective of the BRAF mutation status, but in one NRAS^Q61K mutant cell line it powerfully stimulated cell growth. Synergistic anti-proliferative effects of the combination of metformin with vemurafenib were observed in 6 out of 11 BRAF^V600E mutants, including highly synergistic effects in two BRAF^V600E mutant melanoma cell lines. Antagonistic effects were noted in some cell lines, in particular in BRAF^V600E mutant cell lines resistant to single agent vemurafenib. Seven out of 8 BRAF wild type cell lines showed marginally synergistic anti-proliferative effects with the combination, and one cell line had highly antagonistic effects with the combination. The differential effects were not dependent on the sensitivity to each drug alone, effects on cell cycle or signaling pathways.

Conclusions

The combination of vemurafenib and metformin tended to have stronger anti-proliferative effects on BRAF^V600E mutant cell lines. However, determinants of vemurafenib and metformin synergism or antagonism need to be understood with greater detail before any potential clinical utility of this combination.

Abstract 3584: Effects of the investigational selective MEK inhibitor TAK-733 against cutaneous and uveal melanoma cell lines

Background. There are several MEK inhibitors currently under clinical investigation, including, TAK-733, a novel non-ATP-competitive allosteric selective inhibitor of MEK. We have analyzed the sensitivity of human melanoma cell lines of different origins to TAK-733.

Methods. The half maximal inhibitory concentration (IC50) of TAK-733 was assessed in a panel of 27 skin melanoma cell lines and 5 ocular melanoma cell lines genotyped for driver and secondary oncogenic mutations. Flow cytometry was used to analyze effects on cell cycle progression, and Western blots to analyze the downstream signaling changes upon exposure to TAK-733.

Results. Among 12 BRAFV600E mutated cell lines tested, 6 were sensitive to TAK-733 with IC50s less than 10 nM, including 4 highly sensitive cell lines with IC50s below 1 nM. In 5 cell lines with BRAFV600E mutation the IC50 was higher than 100 nM and were considered highly resistant. Among 10 NRASQ61L mutant melanoma cell lines, 6 were sensitive with IC50s below 10 nM. Among 5 melanoma cell lines with wild type sequences for NRAS, BRAF, GNAQ and GNA11 genes only 1 was sensitive to TAK-733. All 5 of the uveal melanoma cell lines were highly sensitive to TAK-733 IC50 regardless of having a GNAQ or GNA11 mutations. MEK inhibition resulted in increase of pMEK more prominently in NRASQ61L mutant and GNAQ mutant cell lines than in BRAFV600E mutant cell lines. In all cases TAK-733 induced marked dose-dependent inhibition of pERK, regardless of the driver oncogenic mutation or the sensitivity or resistance to this agent in cell viability assays. Cell lines resistant to TAK-733 showed no inhibition of pAKT or pS6K, while there was a general trend towards inhibition of these two phosphorylated molecules in sensitive cell lines.

Conclusions. TAK-733 is a potent MEK inhibitor with high antitumor activity against human melanoma cell lines with BRAF, NRAS, GNAQ and GNA11 driver mutations.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3584. doi:10.1158/1538-7445.AM2011-3584

Melanomas acquire resistance to B-RAF(V600E) inhibition by RTK or N-RAS upregulation

Activating B-RAF(V600E) (also known as BRAF) kinase mutations occur in ∼7% of human malignancies and ∼60% of melanomas. Early clinical experience with a novel class I RAF-selective inhibitor, PLX4032, demonstrated an unprecedented 80% anti-tumour response rate among patients with B-RAF(V600E)-positive melanomas, but acquired drug resistance frequently develops after initial responses. Hypotheses for mechanisms of acquired resistance to B-RAF inhibition include secondary mutations in B-RAF(V600E), MAPK reactivation, and activation of alternative survival pathways. Here we show that acquired resistance to PLX4032 develops by mutually exclusive PDGFRβ (also known as PDGFRB) upregulation or N-RAS (also known as NRAS) mutations but not through secondary mutations in B-RAF(V600E). We used PLX4032-resistant sub-lines artificially derived from B-RAF(V600E)-positive melanoma cell lines and validated key findings in PLX4032-resistant tumours and tumour-matched, short-term cultures from clinical trial patients. Induction of PDGFRβ RNA, protein and tyrosine phosphorylation emerged as a dominant feature of acquired PLX4032 resistance in a subset of melanoma sub-lines, patient-derived biopsies and short-term cultures. PDGFRβ-upregulated tumour cells have low activated RAS levels and, when treated with PLX4032, do not reactivate the MAPK pathway significantly. In another subset, high levels of activated N-RAS resulting from mutations lead to significant MAPK pathway reactivation upon PLX4032 treatment. Knockdown of PDGFRβ or N-RAS reduced growth of the respective PLX4032-resistant subsets. Overexpression of PDGFRβ or N-RAS(Q61K) conferred PLX4032 resistance to PLX4032-sensitive parental cell lines. Importantly, MAPK reactivation predicts MEK inhibitor sensitivity. Thus, melanomas escape B-RAF(V600E) targeting not through secondary B-RAF(V600E) mutations but via receptor tyrosine kinase (RTK)-mediated activation of alternative survival pathway(s) or activated RAS-mediated reactivation of the MAPK pathway, suggesting additional therapeutic strategies.

Validity of the rapid strip assay test for detecting HBsAg in patients admitted to hospital in Uganda

Commercially available rapid strip assays (RSAs) for hepatitis B surface antigen (HBsAg) are used for most routine clinical testing in sub-Saharan Africa. This study evaluated the validity of RSA and a more sophisticated enzyme immunoassay (EIA) with confirmation by nucleic acid testing (NAT) in hospitalized patients in Uganda. Sera from 380 consecutive patients collected and tested for HBsAg and anti-HIV in Kampala, Uganda by RSA were sent frozen to Dallas for EIA including HBsAg, total anti-hepatitis B core, hepatitis B e antigen, and anti-HIV. NAT was performed on all HBsAg-positives and on a random sample of 102 patients that were HBsAg-negative by both assays. Overall, 31 (8%) were HBsAg positive by RSA while 50 (13%) were HBsAg-positive by EIA; 26 were concordant between the two assays. Of 55 HBsAg-positive patients, nearly all showed detectable serum hepatitis B virus (HBV) DNA by bDNA (46) or PCR (4) assay. The 26 patients who were HBsAg positive by both EIA and RSA had significantly higher median serum HBV DNA levels than the 24 patients who were HBsAg positive by EIA alone. An additional 12/102 (12%) HBsAg negative patients had very low serum HBV DNA levels by NAT. Several differences in expected results of serologic testing were observed in this large series of African patients. RSA HBsAg testing is less sensitive than EIA; even EIA failed to detect all HBV DNA positive sera. A more complex testing protocol than RSA alone will be needed in Africa to improve patient care.

Poor performance of hepatitis C antibody tests in hospital patients in Uganda

Most hepatitis C testing in Uganda is performed using commercial rapid strip assays (RSA) to detect antibodies to hepatitis C virus (anti-HCV), rather than enzyme immunoassays (EIA). The prevalence of hepatitis C antibodies in a Ugandan hospital population was determined using both methods to test their accuracy using nucleic acid testing (NAT) as a reference. Sera from 380 consecutive hospitalized Ugandan patients were tested for anti-HCV using an RSA in Uganda, with subsequent automated third-generation EIA testing in the United States, followed by NAT. Recombinant immunoblot assays (RIBA) were used as a supplementary test to detect anti-HCV epitopes. Overall, anti-HCV was detected in 48/380 (13%) by one or both antibody tests. Anti-HCV was detected in 19 (5.0%) patients by RSA and in 33 (8.7%) patients by EIA; only four patients were anti-HCV positive by both methods. Fourteen of the 48 anti-HCV positive patients had detectable serum HCV RNA, 7 each by bDNA assay or by PCR. RSA detected only 7 of 14 HCV RNA positive sera. Of 29 RNA negative but anti-HCV positive patients tested by RIBA, only two were anti-HCV positive; 27 were anti-HCV negative or indeterminate. Anti-HCV testing by RSA and/or EIA was neither sensitive nor specific for detection of ongoing HCV infection in hospitalized Ugandan patients. Our findings underscore the importance of confirmatory nucleic acid testing, which, despite its increased cost, appears essential to manage African patients with HCV.

First Report of Beet mosaic virus Infecting Chickpea (Cicer arietinum) in Tunisia

Chickpea plants with severe yellowing and tip wilting were observed in the Cap-Bon Region of Tunisia in 2006. The viral-like symptoms resulted in yield loss of approximately 25% in some fields. A total of 110 symptomatic chickpea plants was collected from nine chickpea fields and tested at the Virology Laboratory of ICARDA, Syria for eight legume viruses using tissue-blot immunoassay (TBIA) (3). Polyclonal antisera produced at the ICARDA Virology Laboratory were used to test for Chickpea chlorotic dwarf virus (genus Mastrevirus, family Geminiviridae), Broad bean stain virus (genus Comovirus, family Secoviridae), Broad bean mottle virus (genus Bromovirus, family Bromoviridae), and Bean yellow mosaic virus and Pea seed borne mosaic virus (genus Potyvirus, family Potyviridae). Antiserum to Beet mosaic virus (BtMV; genus Potyvirus, family Potyviridae) (AS-0143) was provided by the German Collection of Microorganisms and Cell Cultures (DSMZ, Braunschweig, Germany). In addition, three monoclonal antibodies (MAb) were used to detect Faba bean necrotic yellows virus (FBNYV; genus Nanovirus, family Nanoviridae) (MAb 3-2E9) (1), potyviruses (PVAS-769 [MAb PTY 3 Potyvirus Group] American Type Culture Collection, Manassas, VA), and luteoviruses (MAb B-2-5G4) (2). Twenty-two of the plants tested positive with MAb PTY 3 and BtMV antisera, 56 samples reacted with MAb B-2-5G4, and eight plants with the FBNYV MAb, whereas 24 plants tested negative with all antisera. Because reactions with the BtMV antiserum were unexpected, detection of BtMV was confirmed by reverse transcription-(RT)-PCR assays using BtMV-specific primers (LN26 and LN27) (4), which produced an amplicon of expected size (1,050 bp) from all plants that reacted with BtMV antiserum but not from plants that were serologically negative. Leaf tissue from a BtMV-infected plant was ground in 0.01 M potassium phosphate buffer, pH 7.2 (1:20, wt/vol), mixed with 0.5% celite, and used for mechanical inoculation of chickpea seedlings (cv. Beja 4). In addition, adults of three legume aphid species (Aphis craccivora, A. fabae, and Acyrthosiphon pisum) were starved for 1 h before feeding on BtMV-infected chickpea leaves for an acquisition access period of 5 min. Fifteen aphids of each species were placed on each chickpea plant, allowed to feed for 24 h, and then sprayed with an insecticide. Tip wilting symptoms appeared on plants 15 to 20 days after mechanical and aphid inoculations but not on plants used as negative control treatments (inoculated mechanically with healthy leaf tissue or with aphids that had fed on noninfected chickpea plants). Use of BtMV antiserum for TBIA analysis of inoculated plants revealed systemic BtMV infections in 35 of 92 plants inoculated mechanically and 15 of 75 plants inoculated with viruliferous A. fabae only. To our knowledge, this is the first record of BtMV infecting chickpea in Tunisia. References: (1) A. Franz et al. Ann. Appl. Biol. 128:255, 1996. (2) L. Katul. Characterization by serology and molecular biology of bean leaf roll virus and faba bean necrotic yellows virus. Ph.D. thesis. University of Gottingen, Germany, 1992. (3) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994. (4) L. G. Nemchinov et al. Arch. Virol. 149:1201, 2004.

Differential sensitivity of melanoma cell lines with BRAFV600E mutation to the specific Raf inhibitor PLX4032

Blocking oncogenic signaling induced by the BRAFV600E mutation is a promising approach for melanoma treatment. We tested the anti-tumor effects of a specific inhibitor of Raf protein kinases, PLX4032/RG7204, in melanoma cell lines. PLX4032 decreased signaling through the MAPK pathway only in cell lines with the BRAFV600E mutation. Seven out of 10 BRAFV600E mutant cell lines displayed sensitivity based on cell viability assays and three were resistant at concentrations up to 10 muM. Among the sensitive cell lines, four were highly sensitive with IC50 values below 1 muM, and three were moderately sensitive with IC50 values between 1 and 10 muM. There was evidence of MAPK pathway inhibition and cell cycle arrest in both sensitive and resistant cell lines. Genomic analysis by sequencing, genotyping of close to 400 oncogeninc mutations by mass spectrometry, and SNP arrays demonstrated no major differences in BRAF locus amplification or in other oncogenic events between sensitive and resistant cell lines. However, metabolic tracer uptake studies demonstrated that sensitive cell lines had a more profound inhibition of FDG uptake upon exposure to PLX4032 than resistant cell lines. In conclusion, BRAFV600E mutant melanoma cell lines displayed a range of sensitivities to PLX4032 and metabolic imaging using PET probes can be used to assess sensitivity.

First Report of Faba bean necrotic yellows virus Affecting Legume Crops in Azerbaijan

A total of 482 chickpea (Cicer arietinum L.), 182 lentil (Lens culinaris Medik.), 12 vetch (Vicia sativa L.), 5 field pea (Pisum sativum L.), and 3 faba bean (Vicia faba L.) samples were collected from plants with symptoms suggestive of a viral infection (leaf rolling, yellowing, and stunting) from the major legume-production areas of Azerbaijan in the 2007 and 2008 growing seasons. All samples were tested by the tissue-blot immunoassay (3) at the Virology Laboratory of ICARDA, Syria using 11 specific legume virus antisera including a monoclonal antibody (2-5H9) (1) for Faba bean necrotic yellows virus (FBNYV). Laboratory tests showed that FBNYV was detected in 73, 61, 11, 3, and 2 samples of chickpea, lentil, vetch, field pea, and faba bean, respectively. Total DNA was extracted from six FBNYV-positive samples (two chickpea, two lentil, and two vetch) and tested by PCR with the following four primer sets (FBNYV, Milk vetch dwarf virus [MDV], Subterranean clover stunt virus [SCSV], and nanovirus DNA-R primers [F103 and R101]) (2). All six Azeri samples as well as the reference nanovirus isolates (SCSV-Australia, MDV-Japan, and FBNYV-Syria) generated amplicons of the expected size (~770 bp) using the nanovirus DNA-R primers (F103 & R101). In addition, Azeri samples and FBNYV-Syria yielded a PCR amplicon of the expected size (666 bp) with the FBNYV primer pair. The MDV- and SCSV-specific primers did not generate amplicons with these six samples. Sequence analysis of the FBNYV amplicons from two isolates (AzL 282-07 from lentil [GenBank Accession No. GQ351600] and AzV 277-07 from vetch [GenBank Accession No. GQ371215]) showed that they were 99% identical with each other. Comparing the sequence of AzL 282-07 with that of other nanoviruses revealed identities of 97% (FBNYV-Spain; DQ830990), 96% (FBNYV-Iran; AM493900), 92% (FBNYV-Syria; Y11408), 92% (FBNYV-Egypt; AJ132183), 78% (MDV; AB044387) and 69% (SCSV-Australia; U16734). FBNYV has been reported to infect food legumes in many countries in West Asia and North Africa and cause economic losses on faba bean in Egypt, Jordan, and Syria. To our knowledge, this is the first record of FBNYV infecting legume crops in Azerbaijan. References: (1) A. Franz et al. Ann. Appl. Biol. 128:255, 1996. (2) S. G. Kumari et al. Phytopathol. Mediterr. 47:42, 2008. (3) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994.

CTLA4 blockade increases Th17 cells in patients with metastatic melanoma

Background

Th17 cells are CD4+ cells that produce interleukin 17 (IL-17) and are potent inducers of tissue inflammation and autoimmunity. We studied the levels of this T cell subset in peripheral blood of patients treated with the anti-CTLA4 antibody tremelimumab since its major dose limiting toxicities are inflammatory and autoimmune in nature.

Methods

Peripheral blood mononuclear cells (PBMC) were collected before and after receiving tremelimumab within two clinical trials, one with tremelimumab alone (21 patients) and another together with autologous dendritic cells (DC) pulsed with the melanoma epitope MART-1_26–35 (6 patients). Cytokines were quantified directly in plasma from patients and after in vitro stimulation of PBMC. We also quantified IL-17 cytokine-producing cells by intracellular cytokine staining (ICS).

Results

There were no significant changes in 13 assayed cytokines, including IL-17, when analyzing plasma samples obtained from patients before and after administration of tremelimumab. However, when PBMC were activated in vitro, IL-17 cytokine in cell culture supernatant and Th17 cells, detected as IL-17-producing CD4 cells by ICS, significantly increased in post-dosing samples. There were no differences in the levels of Th17 cells between patients with or without an objective tumor response, but samples from patients with inflammatory and autoimmune toxicities during the first cycle of therapy had a significant increase in Th17 cells.

Conclusion

The anti-CTLA4 blocking antibody tremelimumab increases Th17 cells in peripheral blood of patients with metastatic melanoma. The relation between increases in Th17 cells and severe autoimmune toxicity after CTLA4 blockade may provide insights into the pathogenesis of anti-CTLA4-induced toxicities.

Trial Registration

Clinical trial registration numbers: NCT0090896 and NCT00471887

The Influence of One-step Polishing Systems on the Surface Roughness and Microhardness of Nanocomposites

One-step polishing systems exhibited similar or better surface roughness values when compared to multi-step polishing systems. In all groups, mylar-strip created surfaces showed lower microhardness values than polished surfaces. Different polishing procedures did not effect the microhardness of nanocomposites. One-step polishing systems may be a good choice for polishing nanocomposites, resulting in reduced chair time.

Treatment of hepatitis B with lamivudine and tenofovir in HIV/HBV-coinfected patients: factors associated with response

As therapy for human immunodeficiency virus (HIV) infection evolves, optimizing hepatitis B virus (HBV) treatment and identifying factors that impact its response in the HIV/HBV-coinfected population is critical. We identified retrospectively 45 HBV/HIV-coinfected patients with detectable HBV DNA by the Bayer VERSANT HBV 3.0 bDNA assay (limit of quantification 2000 copies/mL) at baseline and/or year 1 of therapy. Patients were divided into three groups based on the active HBV agent in their antiretroviral regimen: group 1 (n = 15) received lamivudine; group 2 (n = 10), lamivudine plus tenofovir and group 3 (n = 20), lamivudine followed by lamivudine plus tenofovir. HBV genotypes and resistance profiles were determined by the Bayer Trugene HBV 1.0 assay. More patients in group 2 achieved HBV DNA suppression below 2000 copies/mL (80%), loss of HBe antigen (HBeAg) (40%) and loss of HBeAg and gain of anti-HBe (20%) than did patients in group 1 or 3. More patients with HBV genotype A, achieved HBV DNA suppression <2000 copies/mL than did patients with non-A genotypes [74% (26/35) vs 20% (2/10)], respectively (P = 0.003). Risk for virological nonresponse was significant in those with non-A genotypes [odds ratio (OR) 11.1; 95% CI: 2.0-50], previous HIV therapy (OR 6.5; 95% CI: 1.2-35) and <90% compliance (OR 3.7; 95% CI: 0.99-14.3). Simultaneous therapy with lamivudine/tenofovir suppresses HBV DNA more effectively than lamivudine or tenofovir added to lamivudine. More patients infected with HBV genotype A responded than the non-A patients, regardless of therapeutic regimen, compliance or prior HIV therapy.

First Report of Chickpea Chlorotic Dwarf Virus Infecting Spring Chickpea in Syria

During May 2003, a high incidence of symptoms suggestive of virus infection in spring chickpea were observed in many fields in Al-Ghab Valley, Syria, the ICARDA farm (near Aleppo, Syria), as well as in other locations in northern Syria, including the Idleb governorate. Symptoms observed were yellowing, stunting, and necrosis. A total of 1,345 chickpea samples with these symptoms (331 from Al-Ghab Valley, 269 from the ICARDA farm, and 745 from the Idleb governorate) were collected and tested for the presence of five viruses with tissue-blot immunoassay (TBIA) (4) at the Virology Laboratory of ICARDA, using the following antisera: monoclonal antibodies for Faba bean necrotic yellows virus (FBNYV, genus Nanovirus) (1); Bean leafroll virus (BLRV, family Luteoviridae) (4B10) (3); Beet western yellows virus (BWYV, genus Polerovirus, family Luteoviridae [ATCC PVAS-647, American Type Culture Collection, Manassas, VA]); and Soybean dwarf virus (SbDV, family Luteoviridae, [ATCC PVAS-650]) and polyclonal antibodies for Chickpea chlorotic dwarf virus (CpCDV, genus Mastrevirus, family Geminiviridae, provided by H. J. Vetten, BBA, Braunschweig, Germany). The most common virus present was BWYV (detected in 54.1% of samples tested), followed by CpCDV (19.2%), BLRV (10.2%), and FBNYV (5.5%). SbDV was not detected in any of the samples tested. Using immunosorbent electron microscopy, infected chickpea samples revealed low numbers of geminivirus-like particles after 15 min of incubation on CpCDV antiserum-coated grids. When CpCDV was purified from infected chickpea plants, the virus coat protein was 32 kDa with sodium dodecyl sulfate-polyacrylamide gel electrophoresis typical of CpCDV coat protein (2) and reacted strongly with CpCDV antiserum in western blots. The CpCDV vector in Syria was found to be Orosius albicinctus Distant, and is thought to be similar to Orosius orientalis (Matsumura), the reported vector of CpCDV (2). FBNYV, BWYV, and BLRV infection of chickpea have been previously reported from Syria, but to our knowledge, this is the first report of CpCDV infecting chickpea in Syria. References: (1) A. Franz et al. Ann. Appl. Biol. 128:255, 1996. (2) N. M. Horn et al. Ann. Appl. Biol. 122:467, 1993. (3) L. Katul. Characterization by serology and molecular biology of bean leaf roll virus and faba bean necrotic yellows virus. Ph.D. thesis. University of Gottingen, Germany, 1992. (4) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994.

The effect of flowable resin composites as gingival increments on the microleakage of posterior resin composites

Microleakage has been a major concern in restorative dentistry. The curing contraction of composites still presents a problem with controlling microleakage and postoperative sensitivity. This study investigated the effect of flowable materials on gingival microleakage of microhybrid and packable resin composite restorations. Ninety Class II cavities with cervical margins 1 mm below the CEJ were prepared in 45 extracted human premolars. The teeth were randomly divided into three groups (n=15). In each group, one side of each tooth was restored incrementally with respective composites-SureFil, Filtek P60 and Tetric Ceram; whereas, on the other side, flowable materials-Dyract Flow, Filtek Flow or Tetric Flow-were placed respectively as a 1-mm thick gingival increment before the resin composite restoration. The restored teeth were stored for one week in distilled water at 37 degrees C, thermocycled between 5 degrees C and 55 degrees C and immersed in 0.5% basic fuchsin for 24 hours. Dye penetration was evaluated using a stereomicroscope at 10x magnification. The data were analyzed statistically by Kruskal-Wallis analysis of variance and Mann-Whitney U-tests. The effect of flowable increments on reducing the gingival microleakage was found to be statistically significant for all restorative materials tested (p<0.05).

Fluoride release and uptake characteristics of aesthetic restorative materials

The aims of this study were firstly to investigate the fluoride-releasing characteristics of two composite resins (Tetric and Valux Plus), two polyacid-modified resin composites (Compoglass and Dyract), and conventional glass-ionomer cement (Ceramfil beta). The second aim was to assess the fluoride uptake and subsequent release from the same range of materials. Fifteen discs (6 mm diameter and 1.5 mm height) were prepared for each material. Each disc was immersed in 4 ML of deionized water within a plastic vial. The release of fluoride was measured daily at 1, 2, 3, 4, 5, 15, 30 and 60 days. After daily fluoride release was measured for 60 days, samples were refluoridated in 1000-ppm sodium fluoride (NaF) solutions (pH 6.6) for 10 min and fluoride release was measured daily for a total of 5 days. The release of fluoride from aesthetic restorative materials was measured by using specific fluoride electrode and an ionanalyser. Results were statistically analysed by two-way repeated measure ANOVA and Duncan's multiple range test. The results revealed that all fluoride-containing materials (Ceramfil beta, Compoglass, Dyract, Tetric) released fluoride initially and the release was greatest at the first day. At any time during the test period Ceramfil beta released the most and Valux Plus did not release any detectable fluoride (P < 0.01). Sample exposures to 1000 ppm NaF solution increased the 24-h fluoride release from all fluoride-containing materials. This difference lasted only 24-48 h after exposure. Ceramfil beta had a tendency to recharge not seen with the other materials (P < 0.05).

Microleakage of two polyacid-modified resin composites under different conditioning methods in primary teeth

This study evaluated the effect of different conditioning methods on micro-leakage in primary teeth. Fifty-one cervical cavities were prepared on the twenty-six extracted primary molars and divided randomly into five groups. In Group I and IV phosphoric acid, in group 11 non-rinse conditioner (NRC) was applied. In group III and V no pretreatment was used. Groups I-III were restored with Prime & Bond NT and Dyract AP and Group IV-V restored with Syntac SC and Compoglass F. The restored teeth were stored for 24 hours in distilled water at 37 degrees C, immersed in 0.5 percent basic fuchsin for 24 hours. Dye penetration was determined using a stereomicroscope. The results revealed that although enamel microleakage was not affected by the conditioning method used in both restorative materials, pretreating the cavity with phosphoric acid had a positive effect on reducing the dentin microleakage compared with conditioning by NRC.