Hydroxyurea

Distribution by Scientific Domains
Distribution within Medical Sciences

Terms modified by Hydroxyurea

  • hydroxyurea therapy

  • Selected Abstracts


    Hydroxyurea induced skin ulceration in myeloproliferative disorders

    INTERNAL MEDICINE JOURNAL, Issue 3 2000
    C. McLINTOCK
    First page of article [source]


    Synthesis of [11C- carbonyl]hydroxyureas by a rhodium-mediated carbonylation reaction using [11C]carbon monoxide

    JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2006
    Julien Barletta
    Abstract [11C]Hydroxyurea has been successfully labelled using [11C]carbon monoxide at low concentration. The decay-corrected radiochemical yield was 38±3%, and the trapping efficiency of [11C]carbon monoxide in the order of 90±5%. This synthesis was performed by a rhodium-mediated carbonylation reaction starting with azidotrimethylsilane and the rhodium complex being made in situ by chloro(1,5-cyclooctadiene)rhodium(I) dimer ([Rh(cod)Cl]2) and 1,2- bis(diphenylphosphino)ethane (dppe). (13C)Hydroxyurea was synthesized using this method and the position of the labelling was confirmed by 13C-NMR. In order to perform accurate LC,MS identification, the derivative 1-hydroxy-3-phenyl[11C]urea was synthesized in a 35±4% decay-corrected radiochemical yield. After 13 µA h bombardment and 21 min synthesis, 1.6 GBq of pure 1-hydroxy-3-phenyl[11C]urea was collected starting from 6.75 GBq of [11C]carbon monoxide and the specific radioactivity of this compound was in the order of 686 GBq/µmol (3.47 nmol total mass). [11C]Hydroxyurea could be used in conjunction with PET to evaluate the uptake of this anticancer agent into tumour tissue in individual patients. Copyright © 2006 John Wiley & Sons, Ltd. [source]


    Hydroxyurea in children with sickle cell disease: Practice patterns and barriers to utilization,

    AMERICAN JOURNAL OF HEMATOLOGY, Issue 8 2010
    Amanda M. Brandow
    No abstract is available for this article. [source]


    Hydroxyurea in sickle cell disease: What will it take to change practice?,

    AMERICAN JOURNAL OF HEMATOLOGY, Issue 6 2010
    George F. Atweh
    No abstract is available for this article. [source]


    Long-term follow-up of 386 consecutive patients with essential thrombocythemia: Safety of cytoreductive therapy,

    AMERICAN JOURNAL OF HEMATOLOGY, Issue 4 2009
    Francesca Palandri
    Cytotoxic agents like Hydroxyurea, Busulfan and Interferon-alpha are to date the most commonly used therapeutic approaches in Essential Thrombocythemia (ET). However, few data on the efficacy and safety of these agents in the long-term are currently available. We report a retrospective analysis of the long-term outcome of 386 consecutive ET patients, followed at single Institution for a median follow-up of 9.5 years (range, 3,28.5). Cytoreductive therapy was administered to 338 patients (88%), obtaining a response in 86% of cases. Forty-five patients (12%) experienced a thrombosis. Among baseline characteristics, only history of vascular events prior to ET diagnosis predicted a higher incidence of thrombosis. Evolution in acute leukemia/myelofibrosis occurred in 6 (1,5%) and 20 (5%) patients, and was significantly higher in patients receiving sequential cytotoxic agents. Overall survival was 38% at 19 years and was poorer for patients older than 60 years, with higher leukocytes count (>15 × 109/L), hypertension and mellitus diabetes at ET diagnosis and for patients experiencing a thrombotic event during follow-up. Cytoreductive therapy was effective in decreasing platelet number with negligible toxicity; however, thrombocytosis control did not reduce the incidence of thrombosis and, for patients who received sequential therapies, the probability of disease evolution was higher and survival was poorer. Am. J. Hematol. 2009. © 2008 Wiley-Liss, Inc. [source]


    Hydroxyurea therapy lowers circulating DNA levels in sickle cell anemia,

    AMERICAN JOURNAL OF HEMATOLOGY, Issue 9 2008
    Pinar Ulug
    Hydroxyurea reduces the frequency of acute pain in sickle cell disease (SCD). We sought to determine if hydroxyurea therapy affects cell free DNA (cfDNA) levels in SCD. cfDNA levels fell in all 10 patients studied; before hydroxyurea, mean was 1,879 (95% CI 1,104,3,199) GE/mL; after hydroxyurea, mean was 780 (95% CI, 634,959) GE/mL (P = 0.002). Mean cfDNA level in the 10 HbSS adults prior to starting hydroxyurea was also significantly higher than that in 115 HbSS case controls who had never taken hydroxyurea (1,879 vs 975 GE/mL, P = 0.02). cfDNA levels may be useful in monitoring response to hydroxyurea therapy in SCD. Am. J. Hematol., 2008. © 2008 Wiley-Liss, Inc. [source]


    Traditional therapies: glucocorticoids, azathioprine, methotrexate, hydroxyurea

    CLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 7 2002
    G. Belgi
    Summary The ,old favourites' used for treatment of inflammatory diseases, and hence, the original immunomodulators, include the glucocorticoids, azathioprine, methotrexate and hydroxyurea. Glucocorticoids are still one of the most effective anti-inflammatory agents because they work on several different intracellular processes and hence, block many components that contribute to inflammatory and immune responses. They bind to intracellular glucocorticoid receptors which transport them into the nucleus. Here the receptor/steroid complex may bind to many genes that interact with transcription factors including NF,B and AP-1, to inhibit their activation, thereby preventing activation of many genes encoding immune effector and pro-inflammatory cytokines. Also, protein kinases involved in intracellular signalling, are directly activated resulting in phosphorylation of various targets of which Annexin (AXA)-1 is critical in inhibiting biosynthesis of both purines and DNA. This results in reduced proliferation of B and T lymphocytes, reduced immune effector mechanisms and reduced recruitment of mononuclear cells including monocytes into sites of immune inflammation. Methotrexate also blocks DNA synthesis and hence cellular proliferation but also induces release of adenosine. This inhibits chemotaxis of polymorph neutrophils and release of critical cytokines such as TNF-, and Interleukins 6 and 8. Hydroxyurea also inhibits DNA synthesis with inhibitory effects on proliferation of lymphocytes and possibly kerationcytes. Even though many new agents with much greater selectivity are coming through into clinical use, this group of old agents still have an absolutely central position in the therapeutic armamentarium. Their value lies in the fact that they are not ,clean' drugs with narrow effects but they inhibit a wide range of mechanisms involved in immune and inflammatory processes. [source]


    Fulminant bronchiolitis obliterans organizing pneumonia following 2 d of treatment with hydroxyurea, interferon- , and oral cytarabine ocfosfate for chronic myelogenous leukemia

    EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2004
    Georgios Kalambokis
    Abstract:, A 65-yr-old man developed increasing dyspnea and fulminant respiratory failure 48 h after introduction of hydroxyurea, oral cytarabine ocfosfate (YNK01) and interferon- , for treatment of Philadelphia chromosome-positive chronic myelogenous leukemia. The chest radiograph showed bilateral patchy infiltrates while computed tomography revealed multiple bullas, ground glass opacities, and patchy consolidations with possible cavitation. Bronchoscopic examination was normal and microbiological tests performed on all biologic fluids were negative. The patient did not respond to multiple antibiotic treatment and corticosteroid administration and died of progressive respiratory failure 5 d after chemotherapy introduction. The postmortem lung examination was consistent with the diagnosis of bronchiolitis obliterans organizing pneumonia (BOOP). [source]


    Chronic basophilic leukemia: a distinct clinico-pathologic entity?

    EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2003
    Animesh D. Pardanani
    Abstract: Objective: We sought to better define a group of rare and poorly understood myeloproliferative disorders that are characterized by prominent chronic basophilia in the absence of the Philadelphia chromosome (Ph) or its molecular equivalent. Methods: We screened our institution's electronic database from 1975 onwards, and identified four such cases. Clinical data and bone marrow pathology were carefully reviewed for these patients. Results: Two patients had prominent manifestations of basophil mediator-release and another presented with pituitary dysfunction. Bone marrow examination uniformly revealed trilineage hyperplasia with basophilia and eosinophilia, dysplastic megakaryocytic hyperplasia, and the absence of megakaryocyte clustering. An abnormal pattern of atypical mast cells was noted in two cases. While disease palliation was effectively achieved with hydroxyurea for one patient, transformation to acute myeloid leukemia was eventually observed in this case. Another patient has achieved long-term disease-free survival after undergoing allogeneic stem cell transplantation. Conclusions: Our observations reveal a striking pathologic similarity among all four cases, and suggest this disease, which may be aggressive with the potential to transform into acute leukemia, to possibly represent a distinct clinico-pathologic entity (chronic basophilic leukemia). [source]


    Optical tweezers for measuring red blood cell elasticity: application to the study of drug response in sickle cell disease

    EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 4 2003
    M. M. Brandão
    Abstract: The deformability of erythrocytes is a critical determinant of blood flow in microcirculation. By capturing red blood cells (RBC) with optical tweezers and dragging them through a viscous fluid we were able to measure their overall elasticity. We measured, and compared, the RBC deformability of 15 homozygous patients (HbSS) including five patients taking hydroxyurea (HU) for at least 6 months (HbSS/HU), 10 subjects with sickle cell trait (HbAS) and 35 normal controls. Our results showed that the RBC deformability was significantly lower in haemoglobin S (HbS) subjects (HbSS and HbAS), except for HbSS/HU cells, whose deformability was similar to the normal controls. Our data showed that the laser optical tweezers technique is able to detect differences in HbS RBC from subjects taking HU, and to differentiate RBC from normal controls and HbAS, indicating that this is a very sensitive method and can be applied for detection of drug-response in sickle cell disease. [source]


    Acute myeloid leukaemia arising from a patient with untreated essential thrombocythaemia

    EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 6 2002
    Javier Bolaños-Meade
    Abstract:, Acute myeloid leukaemia (AML) is an uncommon complication of patients with essential thrombocythaemia (ET). We report a patient with ET which progressed into AML and who had only received a few days of therapy with hydroxyurea (HU) when diagnosed with ET. This is extremely rare, as in large series no patients who were left untreated for their ET developed this complication. This case supports the theory that AML transformation can be part of the natural history of ET in some cases. [source]


    Treatment of the myeloproliferative disorders with 32P

    EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2000
    Nathaniel I. Berlin
    After World War II when 32P became widely available, it was used extensively to treat the chronic leukemias and polycythemia vera. Its use in the treatment of essential thrombocythemia began later in 1950. Today it is not widely used in the treatment of the chronic leukemia, if at all, its use in polycythemia vera appears to have decreased substantially and replaced by hydroxyurea, and its use in the management of essential thrombocythemia is not widespread. In each instance it has been replaced by a drug developed for use in cancer chemotherapy, and in some instances by interferon. It probably has wider use in polycythemia vera in the rest of Western Europe than in the UK, and there are cogent reasons to suggest that it may be the best tool for the treatment of polycythemia vera. Thus have we discarded a treatment modality that in polycythemia vera may be the best? [source]


    Coordination of DNA replication and cell division in Cyanobacteria Microcystis aeruginosa

    FEMS MICROBIOLOGY LETTERS, Issue 1 2005
    Takashi Yoshida
    Abstract Little is known about the cyanobacterial cell cycle. When either nalidixic acid or hydroxyurea was added to a synchronized culture of Microcystis aeruginosa to block DNA replication, cell division did not occur. Furthermore, transcription of the essential cell division gene, ftsZ was repressed. After DNA replication, ftsZ transcription, as well as cell division, was not affected by hydroxyl urea, suggesting that the DNA replication and cell division of M. aeruginosa are coordinated and that this coordination is partly controlled by ftsZ transcription depending on DNA replication. [source]


    Ability of human CDC25B phosphatase splice variants to replace the function of the fission yeast Cdc25 cell cycle regulator

    FEMS YEAST RESEARCH, Issue 3 2004
    Matthieu Lemaire
    Abstract CDC25 phosphatases are essential and evolutionary-conserved actors of the eukaryotic cell cycle control. To examine and compare the properties of three splicing variants of human CDC25B, recombinant fission yeast strains expressing the human proteins in place of the endogenous Cdc25 were generated and characterized. We report, that the three CDC25B variants: (i) efficiently replace the yeast counterpart in vegetative growth, (ii) partly restore the , and UV radiation DNA damage-activated checkpoint, (iii) fail to restore the DNA replication checkpoint activated by hydroxyurea. Although these yeast strains do not reveal the specific functions of the human CDC25B variants, they should provide useful screening tools for the identification of new cell cycle regulators and pharmacological inhibitors of CDC25 phosphatase. [source]


    Interactions between Swi1-Swi3, Mrc1 and S phase kinase, Hsk1 may regulate cellular responses to stalled replication forks in fission yeast

    GENES TO CELLS, Issue 6 2009
    Michie Shimmoto
    The Swi1-Swi3 replication fork protection complex and Mrc1 protein are required for stabilization of stalled replication forks in fission yeast. Hsk1 kinase also plays roles in checkpoint responses elicited by arrested replication forks. We show that both Swi1 and Swi3, the abundance of which are interdependent, are required for chromatin association of Mrc1. Co-immunoprecipitation experiments show the interactions of Swi1-Swi3, Mrc1 and Hsk1. Mrc1 interacts with Swi3 and Hsk1 proteins through its central segment (378,879) containing a SQ/TQ cluster, and this segment is sufficient for checkpoint reaction. The SQ/TQ cluster segment (536,673) is essential but not sufficient for the interactions and for resistance to replication inhibitor hydroxyurea. Mrc1 protein level is increased in hsk1,89 cells due to apparent stabilization, and we have identified a potential phosphodegron sequence. These results suggest that interactions of the Swi1-Swi3 complex and Hsk1 kinase with Mrc1 may play a role in cellular responses to stalled replication forks in fission yeast. [source]


    Human Mus81 and FANCB independently contribute to repair of DNA damage during replication

    GENES TO CELLS, Issue 10 2007
    Yuji Nomura
    Recent studies suggest a crucial role for homologous recombination (HR) in repairing replication-associated DNA lesions. In mammals, the Mus81 endonuclease and the Fanconi anemia (FA) pathway have been implicated in HR repair; however, their functional relationship has remained unexplored. Here, we knockout the genes for Mus81 and FANCB, a component of the FA core complex, in the human Nalm-6 cell line. We show that Mus81 plays an important role in cell proliferation to suppress cell death when FANCB is missing, indicating a functional linkage between Mus81 and the FA pathway. In DNA cross-link repair, roles for Mus81 and the FA pathway appear to have an overlapping function. Intriguingly, Mus81 and FANCB act independently in surviving exposure to camptothecin (CPT). Although CPT-induced FANCD2 and Mus81 foci co-localize with Rad51, loss of Mus81, but not FANCB, results in significantly decreased levels of spontaneous and CPT-induced sister chromatid exchanges (SCEs). In addition, Mus81, unlike FANCB, has no significant role in gene targeting as well as in repairing hydroxyurea (HU)-induced stalls of replication forks. Collectively, our results provide the first evidence for differential functions of Mus81 and the FA pathway in repair of DNA damage during replication in human cells. [source]


    Dicer-related drh-3 gene functions in germ-line development by maintenance of chromosomal integrity in Caenorhabditis elegans

    GENES TO CELLS, Issue 9 2007
    Masaharu Nakamura
    In the course of systematic RNA interference (RNAi)-based screens with helicase-like genes in Caenorhabditis elegans, we have identified the drh-3(D2005.5) gene as a candidate gene for protection against X-ray irradiation. This gene encodes a novel RNA helicase-like protein that is similar to two nematode Dicer-related helicases (DRH). Here, we have showed the increased expression of drh-3 transcripts during maturation of larvae to adults, and characterized the phenotype of drh-3 -interferred nematodes using feeding RNAi method. RNAi-mediated depletion of the drh-3 transcripts caused embryonic lethality of F1 progeny and temperature-sensitive reproductive capacity but did not affect the nematode life span. F1 progeny from drh-3(RNAi) animals exhibited increased lethality after X-ray irradiation or exposure to camptothecin. In drh-3(RNAi) worms, aggregated chromosomes were observed in diakinesis oocyte nuclei. In developing early zygotic embryos from drh-3(RNAi) worms, abnormally segregated chromosomes were observed and embryonic development was largely arrested at the mid-stages of embryogenesis. Finally, examination of checkpoint responses in mitotic germ cells with regards to replication arrest by hydroxyurea and X-ray-induced DNA damage suggested that both checkpoints function normally under these genotoxic stress conditions. Taken together, these results indicate that the drh-3 gene is essential for the development of germ-lines by maintaining chromosomal integrity in C. elegans. [source]


    Global analysis of functional surfaces of core histones with comprehensive point mutants

    GENES TO CELLS, Issue 1 2007
    Kazuko Matsubara
    The core histones are essential components of the nucleosome that act as global negative regulators of DNA-mediated reactions including transcription, DNA replication and DNA repair. Modified residues in the N-terminal tails are well characterized in transcription, but not in DNA replication and DNA repair. In addition, roles of residues in the core globular domains are not yet well characterized in any DNA-mediated reactions. To comprehensively understand the functional surface(s) of a core histone, we constructed 320 yeast mutant strains, each of which has a point mutation in a core histone, and identified 42 residues responsible for the suppressor of Ty (Spt - ) phenotypes, and 8, 30 and 61 residues for sensitivities to 6-azauracil (6AU), hydroxyurea (HU) and methyl-methanesulfonate (MMS), respectively. In addition to residues that affect one specific assay, residues involved in multiple reactions were found, and surprisingly, about half of them were clustered at either the nucleosome entry site, the surface required for nucleosome,nucleosome interactions in crystal packing or their surroundings. This comprehensive mutation approach was proved to be powerful for identification of the functional surfaces of a core histone in a variety of DNA-mediated reactions and could be an effective strategy for characterizing other evolutionarily conserved hub-like factors for which surface structural information is available. [source]


    VDE-initiated intein homing in Saccharomyces cerevisiae proceeds in a meiotic recombination-like manner

    GENES TO CELLS, Issue 7 2003
    Tomoyuki Fukuda
    Background: Inteins and group I introns found in prokaryotic and eukaryotic organisms occasionally behave as mobile genetic elements. During meiosis of the yeast Saccharomyces cerevisiae, the site-specific endonuclease encoded by VMA1 intein, VDE, triggers a single double-strand break (DSB) at an inteinless allele, leading to VMA1 intein homing. Besides the accumulating information on the in vitro activity of VDE, very little has been known about the molecular mechanism of intein homing in yeast nucleus. Results: We developed an assay to detect the product of VMA1 intein homing in yeast genome. We analysed mutant phenotypes of RecA homologs, Rad51p and Dmc1p, and their interacting proteins, Rad54p and Tid1p, and found that they all play critical roles in intein inheritance. The absence of DSB end processing proteins, Sae2p and those in the Mre11-Rad50-Xrs2 complex, also causes partial reduction in homing efficiency. As with meiotic recombination, crossover events are frequently observed during intein homing. We also observed that the absence of premeiotic DNA replication caused by hydroxyurea (HU) or clb5, clb6, mutation reduces VDE-mediated DSBs. Conclusion: The repairing system working in intein homing shares molecular machinery with meiotic recombination induced by Spo11p. Moreover, like Spo11p-induced DNA cleavage, premeiotic DNA replication is a prerequisite for a VDE-induced DSB. VMA1 intein thus utilizes several host factors involved in meiotic and recombinational processes to spread its genetic information and guarantee its progeny through establishment of a parasitic relationship with the organism. [source]


    The absence of ribonuclease H1 or H2 alters the sensitivity of Saccharomyces cerevisiae to hydroxyurea, caffeine and ethyl methanesulphonate: implications for roles of RNases H in DNA replication and repair

    GENES TO CELLS, Issue 10 2000
    Arulvathani Arudchandran
    Background RNA of RNA-DNA hybrids can be degraded by ribonucleases H present in all organisms including the eukaryote Saccharomyces cerevisiae. Determination of the number and roles of the RNases H in eukaryotes is quite feasible in S. cerevisiae. Results Two S. cerevisiae RNases H, related to Escherichia coli RNase HI and HII, are not required for growth under normal conditions, yet, compared with wild-type cells, a double-deletion strain has an increased sensitivity to hydroxyurea (HU) and is hypersensitive to caffeine and ethyl methanesulphonate (EMS). In the absence of RNase H1, RNase H2 activity increases, and cells are sensitive to EMS but not HU and are more tolerant of caffeine; the latter requires RNase H2 activity. Cells missing only RNase H2 exhibit increased sensitive to HU and EMS but not caffeine Conclusions Mutant phenotypes infer that some RNA-DNA hybrids are recognized by both RNases H1 and H2, while other hybrids appear to be recognized only by RNase H2. Undegraded RNA-DNA hybrids have an effect when DNA synthesis is impaired, DNA damage occurs or the cell cycle is perturbed by exposure to caffeine suggesting a role in DNA replication/repair that can be either beneficial or detrimental to cell viability. [source]


    Mis3 with a conserved RNA binding motif is essential for ribosome biogenesis and implicated in the start of cell growth and S phase checkpoint

    GENES TO CELLS, Issue 7 2000
    Hiroshi Kondoh
    Background In normal somatic cell cycle, growth and cell cycle are properly coupled. Although CDK (cyclin-dependent kinase) activity is known to be essential for cell cycle control, the mechanism to ensure the coupling has been little understood. Results We here show that fission yeast Mis3, a novel evolutionarily highly conserved protein with the RNA-interacting KH motif, is essential for ribosome RNA processing, and implicated in initiating the cell growth. Growth arrest of mis3-224, a temperature sensitive mutant at the restrictive temperature, coincides with the early G2 block in the complete medium or the G1/S block in the release from nitrogen starvation, reflecting coupling of cell growth and division. Genetic interactions indicated that Mis3 shares functions with cell cycle regulators and RNA processing proteins, and is under the control of Dsk1 kinase and PP1 phosphatase. Mis3 is needed for the formation of 18S ribosome RNA, and may hence direct the level of proteins required for the coupling. One such candidate is Mik1 kinase. mis3-224 is sensitive to hydroxyurea, and the level of Mik1 protein increases during replication checkpoint in a manner dependent upon the presence of Mis3 and Cds1. Conclusions Mis3 is essential for ribosome biogenesis, supports S phase checkpoint, and is needed for the coupling between growth and cell cycle. Whether Mis3 interacts solely with ribosomal precursor RNA remains to be determined. [source]


    Nonselective DNA damage induced by a replication inhibitor results in the selective elimination of extrachromosomal double minutes from human cancer cells

    GENES, CHROMOSOMES AND CANCER, Issue 10 2007
    Noriaki Shimizu
    Gene amplification plays a pivotal role in human malignancy. Highly amplified genes frequently localize to extrachromosomal double minutes (dmin), which usually segregate to daughter cells in association with mitotic chromosomes. We and others had shown that treatment with low-dose hydroxyurea (HU) results in the elimination of dmin and reversion of the cancer cell phenotype. HU treatment in early S-phase, when dmin are replicated, results in their detachment from chromosomes at the next M-phase, leading to the appearance of micronuclei enriched in dmin, followed by their elimination. In this article, we examined the effect of low-dose HU on the behavior of dmin in relation to DNA damage induction by simultaneously monitoring LacO-tagged dmin and phosphorylated histone H2AX (,H2AX). As expected, treatment with low-dose HU induced numerous ,H2AX foci throughout the nucleus in early S-phase, and these rarely coincided with dmin. Most chromosomal ,H2AX foci disappeared by metaphase, whereas, unexpectedly, those that persisted frequently associated with dmin. We found that these dmin aggregated, detached from anaphase chromosomes, and apparently formed micronuclei. Because ,H2AX foci likely represent DNA double strand breaks (DSBs), the response to DSBs sustained by extrachromosomal dmin appears to be different from that sustained by chromosomal loci, which may explain why DSB-inducing agents cause the selective elimination of dmin. © 2007 Wiley-Liss, Inc. [source]


    Final report of RTOG 9610, a multi-institutional trial of reirradiation and chemotherapy for unresectable recurrent squamous cell carcinoma of the head and neck,

    HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 3 2008
    Sharon A. Spencer MD
    Abstract Background. Our objectives were to determine the incidence of acute and late toxicities and to estimate the 2-year overall survival for patients treated with reirradiation and chemotherapy for unresectable squamous cell carcinoma of the head and neck (SCCHN). Methods. Patients with recurrent squamous cell carcinoma or a second primary arising in a previously irradiated field were eligible. Four weekly cycles of 5-fluorouracil 300 mg/m2 IV bolus and hydroxyurea 1.5 g by mouth were used with 60 Gy at 1.5 Gy twice-daily fractions. Toxicity was scored according to Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer (RTOG/EORTC) criteria. Results. Seventy-nine of the 86 patients enrolled were analyzable. The worst acute toxicity was grade 4 in 17.7% and grade 5 in 7.6%. Grade 3 and 4 late toxicities were found in 19.4% and 3.0%, respectively. The estimated cumulative incidence of grade 3 to 4 late effects occurring at >1 year was 9.4% (95% confidence interval [CI]: 0, 19.7) at 2 and 5 years. The 2- and 5-year cumulative incidence for grade 4 toxicity was 3.1% (95% CI: 0, 9.3). The estimated 2- and 5-year survival rates were 15.2% (95% CI: 7.3, 23.1) and 3.8% (95% CI: 0.8, 8.0), respectively. Patients who entered the study at >1 year from initial radiotherapy (RT) had better survival than did those who were <1 year from prior RT (median survival, 9.8 months vs 5.8 months; p = .036). No correlation was detected between dose received and overall survival. Three patients were alive at 5 years. Conclusion. This is the first prospective multi-institutional trial testing reirradiation plus chemotherapy for recurrent or second SCCHN. The approach is feasible with acceptable acute and late effects. The results serve as a benchmark for ongoing RTOG trials. © 2007 Wiley Periodicals, Inc. Head Neck 2008 [source]


    Chronic ethanol increases adeno-associated viral transgene expression in rat liver via oxidant and NF,B-dependent mechanisms

    HEPATOLOGY, Issue 5 2000
    Michael D. Wheeler
    Recombinant adeno-associated virus (rAAV) transduction is limited in vivo, yet can be enhanced by hydroxyurea, ultraviolet-irradiation, or adenovirus coinfection, possibly via mechanisms involving stress in the host cell. Because chronic ethanol induces oxidative stress, it was hypothesized that chronic ethanol would increase rAAV transduction in vivo. To test this hypothesis, rAAV encoding ,-galactosidase was given to Wistar rats that later received either ethanol diet or high-fat control diet via an enteral-feeding protocol for 3 weeks. Expression and activity of ,-galactosidase in the liver were increased nearly 5-fold by ethanol. The increase in transgene expression was inhibited by antioxidant diphenylene iodonium (DPI), which is consistent with the hypothesis that ethanol causes an increase in rAAV transduction via oxidative stress. Ethanol increased DNA synthesis only slightly; however, it increased the nuclear transcription factor ,B (NF,B) 4-fold, a phenomenon also sensitive to DPI. Moreover, a 6-fold increase in rAAV transgene expression was observed in an acute ischemia-reperfusion model of oxidative stress. Transgene expression was transiently increased 24 hours after ischemia-reperfusion 3 days and 3 weeks after rAAV infection. Further, adenoviral expression of superoxide dismutase or I,B, superrepressor inhibited rAAV transgene expression caused by ischemia-reperfusion. Therefore, it is concluded that ethanol increases rAAV transgene expression via mechanisms dependent on oxidative stress, and NF,B likely through enhancement of cytomegaloviral (CMV) promoter elements. Alcoholic liver disease is an attractive target for gene therapy because consumption of ethanol could theoretically increase expression of therapeutic genes (e.g., superoxide dismutase). Moreover, this study has important implications for rAAV gene therapy and potential enhancement and regulation of transgene expression in liver. [source]


    Leg ulcers and hydroxyurea: report of three cases with essential thrombocythemia

    INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 12 2002
    Zeynep Demirçay MD
    Case 1,A 65-year-old woman with essential thrombocythemia (ET) had been taking oral hydroxyurea (HU), 1000 mg daily, for 7 years. Six months ago, she developed an ulcer on the outer part of her left ankle, which healed spontaneously within 2 months. She presented with a new, tender, shallow ulcer, 2 cm × 2 cm in size, at the same site. Doppler examination revealed thrombosis of the left common femoral vein and a calcified atheroma plaque of the left common femoral artery. The dosage of HU was decreased to 500 mg daily when the platelet counts were found to be within normal levels. The ulcer completely healed within 2 months with occlusive wound dressings, and has not recurred within the follow-up period of 1 year. Case 2,A 56-year-old women presented with multiple, painful, leg ulcers of 1 year duration. She had been diagnosed as having ET and had been on HU therapy, 1500 mg/day, for the past 5 years. Interferon-,-2b was started 3 months ago, in addition to HU, which was tapered to 1000 mg daily. She had suffered from hypertension for 20 years treated with nifedipine and enalapril, and had recently been diagnosed with diabetes mellitus which was controlled by diet. Examination revealed three ulcers located on the lateral aspects of both ankles and right distal toe. Arterial and venous Doppler examinations were within normal limits. Histopathology of the ulcer revealed nonspecific changes with a mixed inflammatory cell infiltrate around dermal vessels. The ulcers completely healed within 10 weeks with topical hydrocolloid dressings. After healing, she was lost to follow-up. A year later, it was learned that she had developed a new ulcer at her right heel, 3 months after her last visit (by phone call). This ulcer persisted for 8 months until HU was withdrawn. Case 3,A 64-year-old woman with ET presented with a painful leg ulcer of 6 months' duration. She had been taking oral HU for 5 years. She had a 20-year history of hypertension treated with lisinopril. Examination revealed a punched-out ulcer of 2 cm × 2 cm over the right lateral malleolus (Fig. 1). Doppler examination of the veins revealed insufficiency of the right greater saphenous and femoral veins. Angiography showed multiple stenoses of the right popliteal and femoral arteries. As her platelet count remained high, HU was continued. During the follow-up period of 13 months, the ulcer showed only partial improvement with local wound care. Figure 1. Punched-out ulcer surrounded by an erythematous border over the right malleolus (Case 3) [source]


    Hydroxyurea therapy increases plasma erythropoietin in patients with essential thrombocythaemia or polycythaemia vera

    INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 4 2006
    P. JOHANSSON
    Summary The determination of serum/plasma erythropoietin (EPO) concentration has gained widespread use in the diagnosis of polycythaemia vera (PV). A reduced EPO concentration in a newly diagnosed essential thrombocythaemia (ET) seems to be a risk factor for thromboembolic events. In this study plasma EPO concentration was determined before and after initiated hydroxyurea (HU) therapy, 14 patients with PV or ET were included. After 1 month on HU therapy 11 of 14 patients had increased their EPO concentration compared with prior to medication. The plasma EPO was increased in all, except one patient, after 4 months HU therapy. If EPO is incorporated in the diagnostic or prognostic procedures it should be determined before myelosuppressive therapy is initiated. [source]


    Splenectomy in a case of splenic vein thrombosis unmasks essential thrombocythemia

    INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 2 2002
    R. DAS
    We report a patient with splenic vein thrombosis (SVT) in whom splenectomy resulted in the unmasking of essential thrombocythemia (ET). He had portal hypertension with haematemesis, resulting in anaemia requiring repeated blood transfusions. Investigations revealed SVT. Following splenectomy, he suffered a transient ischaemic attack episode, associated with persistent thrombocytosis (> 2000 × 109/l). Other myeloproliferative disorders were excluded and a diagnosis of ET was established. He responded to hydroxyurea but, due to financial constraints, he discontinued treatment and subsequently relapsed. The association of ET with SVT is rare and the diagnosis of ET was missed initially as the platelet count was normal prior to splenectomy. [source]


    Flow cytometric method for simultaneous assay of foetal haemoglobin containing red cells, reticulocytes and foetal haemoglobin containing reticulocytes

    INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 3 2001
    Y. Mundee
    Level of foetal haemoglobin (HbF) containing red cells (F cells) is a parameter for monitoring sickle cell anaemia (SS) patients undergoing treatment with HbF modulating drugs (including hydroxyurea (HU)). One convenient technique for F cell assay is flow cytometry. A flow cytometric method for the simultaneous assay of F cells, reticulocytes and HbF-containing reticulocytes (F reticulocytes) is described in this paper. These three parameters can be obtained within 2 h using double colour staining flow cytometry. Glutaraldehyde fixation, Triton X-100 permeabilization, monoclonal antibody to HbF Tri-colour® conjugate (MoAb-HbF-TC; deep-red fluorescence) immuno-staining and thiazole orange (TO; green fluorescence) are employed. The red cell gate was set on forward scatter (FSC) and logarithmic side scatter (logSSC) for 50 000 cells on the flow cytometer. Fluorescent signals were acquired from fluorescent channel 1 (FL1; green) and (FL4; deep-red). Coefficient of variation percent (%CVs) of intra- and inter-assay were less than 9% and 15%, respectively. EDTA, citrate, heparin and CTAD anticoagulants are all suitable; the samples can be stored at 4°C for up to 6 days. The method is a simple, rapid, convenient, reproducible and useful way of determining F cell, reticulocyte and F reticulocyte levels in sickle cell and thalassaemic patients. [source]


    Effects of histone deacetylase inhibitors on p55CDC/Cdc20 expression in HT29 cell line

    JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2006
    Giuseppe Iacomino
    Abstract In a previous work, taking advantage of the gene-array screening technology, we analysed the effects of histone deacetylase (HDAC) inhibitor sodium butyrate (NaBt), on gene transcription in HT29 human adenocarcinoma cell line. In this study, we focused our attention on p55CDC/Cdc20 gene, whose expression was dramatically reduced by NaBt treatment. Mammalian p55CDC/Cdc20 interacts with the anaphase promoting complex/cyclosome (APC/C), and is involved in regulating anaphase onset and late mitotic events. Using NaBt and trichostatin A (TSA), a member of the HDAC inhibitor family, we showed that both HDAC inhibitors totally downregulated p55CDC/Cdc20 transcription and expression. Cell cycle analysis demonstrated that NaBt arrested HT29 cells in G0/G1 phase, while TSA caused a double block in G0/G1 and G2/M phases. Moreover, p55CDC/Cdc20 showed maximal expression in S and G2/M phases of HT29 cell division cycle. Based on this evidence, and by means of specific cell cycle modulators, such as nocodazole and hydroxyurea, we demonstrated that both TSA and NaBt were responsible for loss of p55CDC/Cdc20 expression, but with different mechanisms of action. Taken together, these results suggest that targeting molecules involved in spindle mitotic checkpoint, such as p55CDC/Cdc20, might account for the high cytotoxicity of HDAC inhibitors versus malignant cells. J. Cell. Biochem. 99: 1122,1131, 2006. © 2006 Wiley-Liss, Inc. [source]


    PPAR,1 synthesis and adipogenesis in C3H10T1/2 cells depends on S-phase progression, but does not require mitotic clonal expansion

    JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2004
    Young C. Cho
    Abstract Adipogenesis is typically stimulated in mouse embryo fibroblast (MEF) lines by a standard hormonal combination of insulin (I), dexamethasone (D), and methylisobutylxanthine (M), administered with a fresh serum renewal. In C3H10T1/2 (10T1/2) cells, peroxisome proliferator-activated receptor ,1 (PPAR,1) expression, an early phase key adipogenic regulator, is optimal after 36 h of IDM stimulation. Although previous studies provide evidence that mitotic clonal expansion of 3T3-L1 cells is essential for adipogenesis, we show, here, that 10T1/2 cells do not require mitotic clonal expansion, but depend on cell cycle progression through S-phase to commit to adipocyte differentiation. Exclusion of two major mitogenic stimuli (DM without insulin and fresh serum renewal) from standard IDM protocol removed mitotic clonal expansion, but sustained equivalent PPAR,1 synthesis and lipogenesis. Different S-phase inhibitors (aphidicolin, hydroxyurea, l -mimosine, and roscovitin) each arrested cells in S-phase, under hormonal stimulation, and completely blocked PPAR,1 synthesis and lipogenesis. However, G2/M inhibitors effected G2/M accumulation of IDM stimulated cells and prevented mitosis, but fully sustained PPAR,1 synthesis and lipogenesis. DM stimulation with or without fresh serum renewal elevated DNA synthesis in a proportion of cells (measured by BrdU labeling) and accumulation of cell cycle progression in G2/M-phase without complete mitosis. By contrast, standard IDM treatments with fresh serum renewal caused elevated DNA synthesis and mitotic clonal expansion while achieved equivalent level of adipogenesis. At most, one-half of the 10T1/2 mixed cell population differentiated to mature adipocytes, even when clonally isolated. PPAR, was exclusively expressed in the cells that contained lipid droplets. IDM stimulated comparable PPAR,1 synthesis and lipogenesis in isolated cells at low cell density (LD) culture, but in about half of the cells and with sensitivity to G1/S, but not G2/M inhibitors. Importantly, growth arrest occurred in all differentiating cells, while continuous mitotic clonal expansion occurred in non-differentiating cells. Irrespective of confluence level, 10T1/2 cells differentiate after progression through S-phase, where adipogenic commitment induced by IDM stimulation is a prerequisite for PPAR, synthesis and subsequent adipocyte differentiation. © 2003 Wiley-Liss, Inc. [source]