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1.
Alzheimers Dement (Amst) ; 16(2): e12588, 2024.
Article in English | MEDLINE | ID: mdl-38638800

ABSTRACT

INTRODUCTION: Patients with Alzheimer's disease present with difficulty in lexical retrieval and reversal of the concreteness effect in nouns. Little is known about the phenomena before the onset of symptoms. We anticipate early linguistic signs in the speech of people who suffer from amnestic mild cognitive impairment (MCI). Here, we report the results of a corpus-linguistic approach to the early detection of cognitive impairment. METHODS: One hundred forty-eight English-speaking Singaporeans provided natural speech data, on topics of their choice; 74 were diagnosed with single-domain MCI (38 amnestic, 36 non-amnestic), 74 cognitively healthy. The recordings yield 267,310 words, which are tagged for parts of speech. We calculate the per-minute word counts and concreteness scores of all tagged words, nouns, and verbs in the dataset. RESULTS: Compared to controls, subjects with amnestic MCI produce fewer but more abstract nouns. Verbs are not affected. DISCUSSION: Slower retrieval of nouns and the reversal of the concreteness effect in nouns are manifested in natural speech and can be detected early through corpus-based analysis. Highlights: Reversal of the concreteness effect is manifested in patients with Alzheimer's disease (AD) and semantic dementia.The paper reports a corpus-based analysis of natural speech by people with amnestic and non-amnestic mild cognitive impairment (MCI) and cognitively healthy controls.People with amnestic MCI produce fewer and more abstract nouns than people with non-amnestic MCI and healthy controls. Verbs appear to be unaffected.The imageability problem can be detected in natural everyday speech by people with amnestic MCI, which carries a higher risk of conversion to AD.

2.
Nat Commun ; 15(1): 2598, 2024 Mar 22.
Article in English | MEDLINE | ID: mdl-38519468

ABSTRACT

Activation of the mechanistic target of rapamycin (mTOR) is a key metabolic checkpoint of pro-inflammatory T-cell development that contributes to the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE), however, the underlying mechanisms remain poorly understood. Here, we identify a functional role for Rab4A-directed endosome traffic in CD98 receptor recycling, mTOR activation, and accumulation of mitochondria that connect metabolic pathways with immune cell lineage development and lupus pathogenesis. Based on integrated analyses of gene expression, receptor traffic, and stable isotope tracing of metabolic pathways, constitutively active Rab4AQ72L exerts cell type-specific control over metabolic networks, dominantly impacting CD98-dependent kynurenine production, mTOR activation, mitochondrial electron transport and flux through the tricarboxylic acid cycle and thus expands CD4+ and CD3+CD4-CD8- double-negative T cells over CD8+ T cells, enhancing B cell activation, plasma cell development, antinuclear and antiphospholipid autoantibody production, and glomerulonephritis in lupus-prone mice. Rab4A deletion in T cells and pharmacological mTOR blockade restrain CD98 expression, mitochondrial metabolism and lineage skewing and attenuate glomerulonephritis. This study identifies Rab4A-directed endosome traffic as a multilevel regulator of T cell lineage specification during lupus pathogenesis.


Subject(s)
Glomerulonephritis , Lupus Erythematosus, Systemic , Animals , Mice , CD8-Positive T-Lymphocytes/metabolism , Endosomes/metabolism , Glomerulonephritis/metabolism , Kynurenine/metabolism , Mitochondria/metabolism , Mitophagy , TOR Serine-Threonine Kinases/metabolism , rab4 GTP-Binding Proteins/metabolism
3.
Ther Adv Hematol ; 13: 20406207221080743, 2022.
Article in English | MEDLINE | ID: mdl-35237397

ABSTRACT

The heterogeneity in disease pathology, the unpredictability in disease prognosis, and the variability in response to therapy make mantle cell lymphoma (MCL) a focus of novel therapeutic development. MCL is characterized by dysregulated expression of cyclin D1 through a chromosome t(11;14) translocation. MCL international prognostic index (MIPI), ki-67 proliferation index, and TP53 mutation status are currently utilized for prognostication. With advances in pharmacokinetic analysis and drug discovery, treatment strategy has evolved from chemotherapy to combination of targeted, epigenetic, and immune therapies. In this review, we discuss investigational and newly approved treatment approaches. In a short time, the US Food and Drug Administration (FDA) has approved five agents for the treatment of MCL: lenalidomide, an immunomodulatory agent; bortezomib, a proteasome inhibitor; and ibrutinib, acalabrutinib, and zanubrutinib, all Bruton kinase inhibitors. Epigenetic agents (e.g. cladribine and vorinostat), mammalian target of rapamycin (mTOR) inhibitors (e.g. temsirolimus and everolimus), and monoclonal antibodies and/or antibody-drug conjugates (e.g. obinutuzumab, polatuzumab, and ublituximab) are promising therapeutic agents currently under clinical trial investigation. Most recently, chimeric antigen receptor (CAR)-T cell therapy and bispecific T-cell engager (BiTE) therapy even open a new venue for MCL treatment. However, due to its intricate pathology nature and high relapse incidence, there are still unmet needs in developing optimal therapeutic strategies for both frontline and relapsed/refractory settings. The ultimate goal is to develop innovative personalized combination therapy approaches for the purpose of delivering precision medicine to cure this disease.

4.
Case Rep Med ; 2021: 4256471, 2021.
Article in English | MEDLINE | ID: mdl-34970316

ABSTRACT

A 67-year-old female patient presented asymptomatically for further evaluation of a chest mass. Other than significant smoking history, the patient had been healthy with a recently treated case of uncomplicated pneumonia. The mass originated in the aortopulmonary window of the left mediastinum and invaded proximally into the left superior pulmonary vein and subsequently into the left atrium. The mass protrusion into the mitral valve occupied 50% of the left atrium space but showed no clinical symptoms of a valvular blockade. Poorly differentiated squamous cell carcinoma was identified upon biopsy. These findings of a primary lung tumor with atrial extension in an asymptomatic patient point to the importance of age-appropriate screening and standardization treatment modalities.

5.
Lupus Sci Med ; 7(1)2020 04.
Article in English | MEDLINE | ID: mdl-32343673

ABSTRACT

OBJECTIVES: Recent investigations in humans and mouse models with lupus have revealed evidence of mitochondrial dysfunction and production of mitochondrial reactive oxygen species (mROS) in T cells and neutrophils. This can provoke numerous cellular changes including oxidation of nucleic acids, proteins, lipids and even induction of cell death. We have previously observed that in T cells from patients with lupus, the increased mROS is capable of provoking oligomerisation of mitochondrial antiviral stimulator (MAVS) and production of type I interferon (IFN-I). mROS in SLE neutrophils also promotes the formation of neutrophil extracellular traps (NETs), which are increased in lupus and implicated in renal damage. As a result, in addition to traditional immunosuppression, more comprehensive treatments for lupus may also include non-immune therapy, such as antioxidants. METHODS: Lupus-prone MRL-lpr mice were treated from weaning for 11 weeks with the mitochondria-targeted antioxidant, MitoQ (200 µM) in drinking water. Mice were then assessed for ROS production in neutrophils, NET formation, MAVS oligomerisation, serum IFN-I, autoantibody production and renal function. RESULTS: MitoQ-treated mice manifested reduced neutrophil ROS and NET formation, decreased MAVS oligomerisation and serum IFN-I, and reduced immune complex formation in kidneys, despite no change in serum autoantibody . CONCLUSIONS: These findings reveal the potential utility of targeting mROS in addition to traditional immunosuppressive therapy for lupus.


Subject(s)
Extracellular Traps/immunology , Kidney Diseases/metabolism , Lupus Erythematosus, Systemic/immunology , Mitochondria/metabolism , Organophosphorus Compounds/pharmacology , Ubiquinone/analogs & derivatives , Animals , Autoantibodies/metabolism , Disease Models, Animal , Female , Humans , Interferon Type I/immunology , Kidney/metabolism , Kidney/physiopathology , Kidney Diseases/physiopathology , Lupus Erythematosus, Systemic/physiopathology , Male , Mice , Mice, Inbred MRL lpr , Neutrophils/immunology , Oxidation-Reduction/drug effects , Oxidative Stress/immunology , Reactive Oxygen Species/metabolism , T-Lymphocytes/immunology , Ubiquinone/pharmacology
6.
JCI Insight ; 5(1)2020 01 16.
Article in English | MEDLINE | ID: mdl-31805010

ABSTRACT

Overexpression and long terminal repeat (LTR) polymorphism of the HRES­1/Rab4 human endogenous retrovirus locus have been associated with T cell activation and disease manifestations in systemic lupus erythematosus (SLE). Although genomic DNA methylation is diminished overall in SLE, its role in HRES-1/Rab4 expression is unknown. Therefore, we determined how lupus-associated polymorphic rs451401 alleles of the LTR regulate transcription from the HRES-1/Rab4 promoter and thus affect T cell activation. The results showed that cytosine-119 is hypermethylated while cytosine-51 of the promoter and the LTR enhancer are hypomethylated in SLE. Pharmacologic or genetic inactivation of DNA methyltransferase 1 augmented the expression of HRES-1/Rab4. The minimal promoter was selectively recognized by metabolic stress sensor NRF1 when cytosine-119 but not cytosine-51 was methylated, and NRF1 stimulated HRES-1/Rab4 expression in human T cells. In turn, IRF2 and PSIP1 bound to the LTR enhancer and exerted control over HRES-1/Rab4 expression in rs451401 genotype- and methylation-dependent manners. The LTR enhancer conferred markedly greater expression of HRES-1/Rab4 in subjects with rs451401CC over rs451401GG alleles that in turn promoted mechanistic target of rapamycin (mTOR) activation upon T cell receptor stimulation. HRES-1/Rab4 alone robustly activated mTOR in human T cells. These findings identify HRES-1/Rab4 as a methylation- and rs451401 allele-dependent transducer of environmental stress and controller of T cell activation.


Subject(s)
Endogenous Retroviruses/genetics , Epigenesis, Genetic , Lupus Erythematosus, Systemic/genetics , TOR Serine-Threonine Kinases/genetics , Terminal Repeat Sequences/genetics , Adaptor Proteins, Signal Transducing , Adolescent , Adult , Aged , Alleles , DNA (Cytosine-5-)-Methyltransferase 1 , DNA Methylation , Female , HCT116 Cells , HeLa Cells , Humans , Middle Aged , Nuclear Respiratory Factor 1 , Receptors, Antigen, T-Cell , T-Lymphocytes , Terminal Repeat Sequences/physiology , Transcription Factors , Young Adult
7.
Trends Immunol ; 39(7): 562-576, 2018 07.
Article in English | MEDLINE | ID: mdl-29739666

ABSTRACT

Metabolic pathways are now well recognized as important regulators of immune differentiation and activation, and thus influence the development of autoimmune diseases such as systemic lupus erythematosus (SLE). The mechanistic target of rapamycin (mTOR) has emerged as a key sensor of metabolic stress and an important mediator of proinflammatory lineage specification. Metabolic pathways control the production of mitochondrial reactive oxygen species (ROS), which promote mTOR activation and also modulate the antigenicity of proteins, lipids, and DNA, thus placing ROS at the heart of metabolic disturbances during pathogenesis of SLE. Therefore, we review here the pathways that control ROS production and mTOR activation and identify targets for safe therapeutic modulation of the signaling network that underlies autoimmune diseases, focusing on SLE.


Subject(s)
Autoimmune Diseases/metabolism , Metabolic Networks and Pathways/physiology , Animals , Humans , Reactive Oxygen Species/metabolism , Signal Transduction/physiology
8.
Behav Brain Sci ; 40: e289, 2017 01.
Article in English | MEDLINE | ID: mdl-29342718

ABSTRACT

A critical flaw in Branigan & Pickering's (B&P's) advocacy of structural priming is the absence of a theory of priming. This undermines their claims about the value of priming as a methodology. In contrast, acceptability judgments enable clearer inferences about structure. It is important to engage thoroughly with the logic behind different structural diagnostics.


Subject(s)
Judgment , Linguistics , Logic
9.
J Hematol Oncol ; 9(1): 136, 2016 12 08.
Article in English | MEDLINE | ID: mdl-27927231

ABSTRACT

BACKGROUND: Megakaryocytic cell maturation involves polyploidization, and megakaryocyte (MK) ploidy correlates with their maturation and platelet production. Retardation of MK maturation is closely associated with poor MK engraftment after cord blood transplantation and neonatal thrombocytopenia. Despite the high prevalence of thrombocytopenia in a range of setting that affect infants to adults, there are still very limited modalities of treatment. METHODS: Human CD34+ cells were isolated from cord blood or bone marrow samples acquired from consenting patients. Cells were cultured and induced using 616452 and compared to current drugs on the market such as rominplostim or TPO. Ploidy analysis was completed using propidium iodide staining and flow cytometry analysis. Animal studies consisted of transplanting human CD34+ cells into NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ mice followed by daily injections of 15 mg/kg of 616452. RESULTS: Within one week of culture, the chemical was able to induce polyploidization, the process required for megakaryocyte maturation with the accumulation of DNA content, to 64 N or greater to achieve a relative adult size. We observed fold increases as high as 200-fold in cells of 16 N or greater compared to un-induced cells with a dose-dependent manner. In addition, MK differentiated in the presence of 616452 demonstrated a more robust capacity of MK differentiation than that of MKs cultured with rominplostim used for adult idiopathic thrombocytopenic purpura (ITP) patients. In mice transplanted with human cord blood, 616452 strikingly enhanced MK reconstitution in the marrow and human peripheral platelet production. The molecular therapeutic actions for this chemical may be through TPO-independent pathways. CONCLUSION: Our studies may have an important impact on our fundamental understanding of fetal MK biology, the clinical management of thrombocytopenic neonates and leukemic differentiation therapy.


Subject(s)
Blood Platelets/cytology , Hematopoiesis , Megakaryocytes/cytology , Stem Cells/cytology , Animals , Antigens, CD34/analysis , Bone Marrow Cells/cytology , Cell Culture Techniques/methods , Cells, Cultured , Fetal Blood/cytology , Hematopoiesis/drug effects , Heterografts , Humans , Megakaryocytes/drug effects , Mice , Ploidies , Pyrazoles/pharmacology , Pyridines/pharmacology
10.
Curr Rheumatol Rep ; 18(12): 73, 2016 Dec.
Article in English | MEDLINE | ID: mdl-27812954

ABSTRACT

The mechanistic target of rapamycin (mTOR) is a central regulator in cell growth, activation, proliferation, and survival. Activation of the mTOR pathway underlies the pathogenesis of systemic lupus erythematosus (SLE). While mTOR activation and its therapeutic reversal were originally discovered in T cells, recent investigations have also uncovered roles in other cell subsets including B cells, macrophages, and "non-immune" organs such as the liver and the kidney. Activation of mTOR complex 1 (mTORC1) precedes the onset of SLE and associated co-morbidities, such as anti-phospholipid syndrome (APS), and may act as an early marker of disease pathogenesis. Six case reports have now been published that document the development of SLE in patients with genetic activation of mTORC1. Targeting mTORC1 over-activation with N-acetylcysteine, rapamycin, and rapalogs provides an opportunity to supplant current therapies with severe side effect profiles such as prednisone or cyclophosphamide. In the present review, we will discuss the recent explosion of findings in support for a central role for mTOR activation in SLE.


Subject(s)
B-Lymphocytes/metabolism , Lupus Erythematosus, Systemic/metabolism , T-Lymphocytes/metabolism , TOR Serine-Threonine Kinases/metabolism , Acetylcysteine/therapeutic use , Humans , Immunosuppressive Agents/therapeutic use , Lupus Erythematosus, Systemic/drug therapy , Sirolimus/therapeutic use
11.
Fed Pract ; 33(Suppl 5): 60S-62S, 2016 Aug.
Article in English | MEDLINE | ID: mdl-30766225

ABSTRACT

Treatment of reverse pseudohyperkalemia for a patient with chronic lymphocytic leukemia was complicated by falsely reported elevated potassium levels.

12.
Stem Cells Transl Med ; 4(7): 755-63, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25972144

ABSTRACT

UNLABELLED: : Cellular reprogramming or conversion is a promising strategy to generate desired stem cell types from somatic cells. Neural stem cells (NSCs) have the potential to regenerate central nervous system tissue and repair damage in response to injury. However, NSCs are difficult to isolate from human tissues and expand in sufficient quantities for therapy. Here, we report a method to generate neural stem cells from cord blood CD34-positive cells by ectopic expression of OCT4 in a feeder-free system. The induced cells (iNSCs) show a characteristic NSC-like morphology and can be expanded in vitro for more than 20 passages. In addition, the iNSCs are positive for neural stem cell-specific markers such as Nestin and Musashi-1 and are similar in gene expression patterns to a human neural stem cell line. The iNSCs express distinct transcriptional factors for forebrain, hindbrain, and spinal cord regions. Upon differentiation, the iNSCs are able to commit into multilineage mature neural cells. Following in vivo introduction into NOD/SCID mice, iNSCs can survive and differentiate in the mouse brain 3 months post-transplantation. Alternatively, we were also able to derive iNSCs with an episomal vector expressing OCT4. Our results suggest a novel, efficient approach to generate neural precursor cells that can be potentially used in drug discovery or regenerative medicine for neurological disease and injury. SIGNIFICANCE: This study describes a novel method to generate expandable induced neural stem cells from human cord blood cells in a feeder-free system by a single factor, OCT4. The data are promising for future applications that require the generation of large amounts of autologous neural stem cells in disease modeling and regenerative medicine.

13.
PLoS One ; 7(6): e38368, 2012.
Article in English | MEDLINE | ID: mdl-22701632

ABSTRACT

The omentum is a sheet-like tissue attached to the greater curvature of the stomach and contains secondary lymphoid organs called milky spots. The omentum has been used for its healing potential for over 100 years by transposing the omental pedicle to injured organs (omental transposition), but the mechanism by which omentum helps the healing process of damaged tissues is not well understood. Omental transposition promotes expansion of pancreatic islets, hepatocytes, embryonic kidney, and neurons. Omental cells (OCs) can be activated by foreign bodies in vivo. Once activated, they become a rich source for growth factors and express pluripotent stem cell markers. Moreover, OCs become engrafted in injured tissues suggesting that they might function as stem cells.Omentum consists of a variety of phenotypically and functionally distinctive cells. To understand the mechanism of tissue repair support by the omentum in more detail, we analyzed the cell subsets derived from the omentum on immune and inflammatory responses. Our data demonstrate that the omentum contains at least two groups of cells that support tissue repair, immunomodulatory myeloid derived suppressor cells and omnipotent stem cells that are indistinguishable from mesenchymal stem cells. Based on these data, we propose that the omentum is a designated organ for tissue repair and healing in response to foreign invasion and tissue damage.


Subject(s)
Lung Injury/therapy , Omentum/physiology , Regeneration/physiology , Tissue Engineering/methods , Tissue Transplantation/methods , Totipotent Stem Cells/transplantation , Analysis of Variance , Animals , Bleomycin/toxicity , Blotting, Western , Bronchoalveolar Lavage , Cell Proliferation , DNA Primers/genetics , Flow Cytometry , Fluorescent Antibody Technique , Lung Injury/chemically induced , Mice , Mice, Inbred C57BL , Nitric Oxide Synthase Type II/metabolism , Omentum/cytology , Omentum/transplantation , Osteopontin/metabolism , Reverse Transcriptase Polymerase Chain Reaction , T-Lymphocytes/physiology , Tissue Transplantation/physiology , Totipotent Stem Cells/physiology
14.
Biochemistry ; 51(10): 2087-99, 2012 Mar 13.
Article in English | MEDLINE | ID: mdl-22360279

ABSTRACT

Although several reports have documented nitric oxide (NO) regulation of biofilm formation, the molecular basis of this phenomenon is unknown. In many bacteria, an H-NOX (heme-nitric oxide/oxygen-binding) gene is found near a diguanylate cyclase (DGC) gene. H-NOX domains are conserved hemoproteins that are known NO sensors. It is widely recognized that cyclic di-GMP (c-di-GMP) is a ubiquitous bacterial signaling molecule that regulates the transition between motility and biofilm. Therefore, NO may influence biofilm formation through H-NOX regulation of DGC, thus providing a molecular-level explanation for NO regulation of biofilm formation. This work demonstrates that, indeed, NO-bound H-NOX negatively affects biofilm formation by directly regulating c-di-GMP turnover in Shewanella woodyi strain MS32. Exposure of wild-type S. woodyi to a nanomolar level of NO resulted in the formation of thinner biofilms, and less intracellular c-di-GMP, than in the absence of NO. Also, a mutant strain in the gene encoding SwH-NOX showed a decreased level of biofilm formation (and a decreased amount of intracellular c-di-GMP) with no change observed upon NO addition. Furthermore, using purified proteins, it was demonstrated that SwH-NOX and SwDGC are binding partners. SwDGC is a dual-functioning DGC; it has diguanylate cyclase and phosphodiesterase activities. These data indicate that NO-bound SwH-NOX enhances c-di-GMP degradation, but not synthesis, by SwDGC. These results support the biofilm growth data and indicate that S. woodyi senses nanomolar NO with an H-NOX domain and that SwH-NOX regulates SwDGC activity, resulting in a reduction in c-di-GMP concentration and a decreased level of biofilm growth in the presence of NO. These data provide a detailed molecular mechanism for NO regulation of c-di-GMP signaling and biofilm formation.


Subject(s)
Cyclic GMP/analogs & derivatives , Nitric Oxide/metabolism , Shewanella/physiology , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Base Sequence , Biofilms/growth & development , Cyclic GMP/biosynthesis , Cyclic GMP/metabolism , DNA, Bacterial/genetics , Escherichia coli Proteins/genetics , Escherichia coli Proteins/metabolism , Genes, Bacterial , Hydrolysis , Kinetics , Models, Biological , Mutation , Phosphoric Diester Hydrolases/genetics , Phosphoric Diester Hydrolases/metabolism , Phosphorus-Oxygen Lyases/genetics , Phosphorus-Oxygen Lyases/metabolism , Shewanella/genetics , Signal Transduction
15.
DNA Repair (Amst) ; 9(6): 708-17, 2010 Jun 04.
Article in English | MEDLINE | ID: mdl-20457012

ABSTRACT

We have addressed the role of the F-box helicase 1 (Fbh1) protein during genome maintenance in mammalian cells. For this, we generated two mouse embryonic stem cell lines deficient for Fbh1: one with a homozygous deletion of the N-terminal F-box domain (Fbh1(f/f)), and the other with a homozygous disruption (Fbh1(-/-)). Consistent with previous reports of Fbh1-deficiency in vertebrate cells, we found that Fbh1(-/-) cells show a moderate increase in Rad51 localization to DNA damage, but no clear defect in chromosome break repair. In contrast, we found that Fbh1(f/f) cells show a decrease in Rad51 localization to DNA damage and increased cytoplasmic localization of Rad51. However, these Fbh1(f/f) cells show no clear defects in chromosome break repair. Since some Rad51 partners and F-box-associated proteins (Skp1-Cul1) have been implicated in progression through mitosis, we considered whether Fbh1 might play a role in this process. To test this hypothesis, we disrupted mitosis using catalytic topoisomerase II inhibitors (bisdioxopiperazines), which inhibit chromosome decatenation. We found that both Fbh1(f/f) and Fbh1(-/-) cells show hypersensitivity to topoisomerase II catalytic inhibitors, even though the degree of decatenation stress was not affected. Furthermore, following topoisomerase II catalytic inhibition, both Fbh1-deficient cell lines show substantial defects in anaphase separation of chromosomes. These results indicate that Fbh1 is important for restoration of normal mitotic progression following decatenation stress.


Subject(s)
Chromosome Breakage , DNA Helicases/metabolism , Mitosis/physiology , Stress, Physiological/genetics , Anaphase/drug effects , Anaphase/genetics , Animals , Biocatalysis , Cell Line , Cell Nucleus/drug effects , Cell Nucleus/metabolism , Cell Survival/drug effects , Chromosome Breakage/drug effects , DNA Helicases/deficiency , DNA Helicases/genetics , DNA Topoisomerases, Type II/metabolism , DNA, Catenated/metabolism , Diketopiperazines , Embryonic Stem Cells/cytology , Embryonic Stem Cells/drug effects , Embryonic Stem Cells/metabolism , F-Box Proteins , Gene Deletion , Homozygote , Humans , Mice , Piperazines/pharmacology , Protein Transport , Rad51 Recombinase/metabolism , Stress, Physiological/drug effects , Topoisomerase II Inhibitors
16.
PLoS Genet ; 4(6): e1000110, 2008 Jun 27.
Article in English | MEDLINE | ID: mdl-18584027

ABSTRACT

Characterizing the functional overlap and mutagenic potential of different pathways of chromosomal double-strand break (DSB) repair is important to understand how mutations arise during cancer development and treatment. To this end, we have compared the role of individual factors in three different pathways of mammalian DSB repair: alternative-nonhomologous end joining (alt-NHEJ), single-strand annealing (SSA), and homology directed repair (HDR/GC). Considering early steps of repair, we found that the DSB end-processing factors KU and CtIP affect all three pathways similarly, in that repair is suppressed by KU and promoted by CtIP. In contrast, both KU and CtIP appear dispensable for the absolute level of total-NHEJ between two tandem I-SceI-induced DSBs. During later steps of repair, we find that while the annealing and processing factors RAD52 and ERCC1 are important to promote SSA, both HDR/GC and alt-NHEJ are significantly less dependent upon these factors. As well, while disruption of RAD51 causes a decrease in HDR/GC and an increase in SSA, inhibition of this factor did not affect alt-NHEJ. These results suggest that the regulation of DSB end-processing via KU/CtIP is a common step during alt-NHEJ, SSA, and HDR/GC. However, at later steps of repair, alt-NHEJ is a mechanistically distinct pathway of DSB repair, and thus may play a unique role in mutagenesis during cancer development and therapy.


Subject(s)
Chromosome Breakage , Chromosomes, Mammalian/genetics , DNA Breaks, Double-Stranded , DNA Repair , Animals , Antigens, Nuclear/genetics , Antigens, Nuclear/metabolism , Carrier Proteins/genetics , Carrier Proteins/metabolism , Cell Line , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Deoxyribonucleases, Type II Site-Specific/genetics , Deoxyribonucleases, Type II Site-Specific/metabolism , Endodeoxyribonucleases , Endonucleases/genetics , Endonucleases/metabolism , Genes, Reporter , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Humans , Ku Autoantigen , Mice , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Rad51 Recombinase/genetics , Rad51 Recombinase/metabolism , Rad52 DNA Repair and Recombination Protein/genetics , Rad52 DNA Repair and Recombination Protein/metabolism , Saccharomyces cerevisiae Proteins
17.
Am J Vet Res ; 67(9): 1476-83, 2006 Sep.
Article in English | MEDLINE | ID: mdl-16948589

ABSTRACT

OBJECTIVE: To compare anesthesia-related events associated with IV administration of 2 novel micellar microemulsion preparations (1% and 5%) and a commercially available formulation (1%) of propofol in horses. Animals-9 healthy horses. PROCEDURES: On 3 occasions, each horse was anesthetized with 1 of the 3 propofol formulations (1% or 5% microemulsion or 1% commercial preparation). All horses received xylazine (1 mg/kg, IV), and anesthesia was induced with propofol (2 mg/kg, IV). Induction and recovery events were quantitatively and qualitatively assessed. Venous blood samples were obtained before and at intervals following anesthesia for quantification of clinicopathologic variables. RESULTS: Compared with the commercial formulation, the quality of anesthesia induction in horses was slightly better with the micellar microemulsion formulas. In contrast, recovery characteristics were qualitatively and quantitatively indistinguishable among treatment groups (eg, time to stand after anesthesia was 34.3 +/- 7.3 minutes, 34.1 +/- 8.8 minutes, and 39.0 +/- 7.6 minutes in horses treated with the commercial formulation, 1% microemulsion, and 5% microemulsion, respectively). During recovery from anesthesia, all horses stood on the first attempt and walked within 5 minutes of standing. No clinically relevant changes in hematologic and serum biochemical analytes were detected during a 3-day period following anesthesia. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the micellar microemulsion preparation of propofol (1% or 5%) has similar anesthetic effects in horses, compared with the commercially available lipid propofol formulation. Additionally, the micellar microemulsion preparation is anticipated to have comparatively low production costs and can be manufactured in various concentrations.


Subject(s)
Anesthesia Recovery Period , Anesthesia/veterinary , Anesthetics, Intravenous/administration & dosage , Horses/physiology , Propofol/administration & dosage , Anesthetics, Intravenous/chemistry , Animals , Blood Cell Count/veterinary , Blood Chemical Analysis/veterinary , Body Temperature/drug effects , Cross-Over Studies , Dose-Response Relationship, Drug , Emulsions/administration & dosage , Emulsions/chemistry , Female , Heart Rate/drug effects , Horses/blood , Male , Micelles , Propofol/chemistry , Respiration/drug effects
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