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Davis RL, Liang C, Edema-Hildebrand F, Riley C, Needham M, Sue CM. Fibroblast growth factor 21 is a sensitive biomarker of mitochondrial disease. Neurology 2013; 81:1819-26. [PMID: 24142477 DOI: 10.1212/01.wnl.0000436068.43384.ef] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To prospectively determine the reliability and validity of serum fibroblast growth factor 21 (FGF-21) as a biomarker for mitochondrial disease in a cross-sectional cohort of adults with mitochondrial disease from a specialist primary care and tertiary referral clinic. METHODS We recruited 140 subjects, including 54 adults with mitochondrial disease, 20 patients with nonmitochondrial neuromuscular disease, and 66 control subjects, between November 2011 and October 2012. We compared serum FGF-21 concentrations to classical biomarkers, serum creatine kinase, lactate, pyruvate, and lactate to pyruvate ratio, to determine its validity and reliability as a biomarker of mitochondrial disease. We determined the sensitivity, odds ratio (OR), and overall reliability of FGF-21 as a marker of mitochondrial disease using statistical analyses. RESULTS Median serum FGF-21 concentrations were significantly elevated in patients with mitochondrial disease and differed significantly between all experimental groups. FGF-21 showed a markedly higher diagnostic OR (45.7 [95% confidence interval = 12.6-166.5], p < 0.0001) when compared to other biomarkers and was the best predictor of disease according to sensitivity and receiver operating characteristic curve analysis. After multivariate logistic regression analysis controlling for potential confounders, FGF-21 was the only measured parameter capable of predicting mitochondrial disease. CONCLUSION This prospective study establishes serum FGF-21 levels as a sensitive biomarker of mitochondrial disease and demonstrates that they are the best predictor of this disorder when compared to serum levels of classical indicators: creatine kinase, lactate, pyruvate, and the lactate to pyruvate ratio.
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Wei WQ, Feng Q, Jiang L, Waitara MS, Iwuchukwu OF, Roden DM, Jiang M, Xu H, Krauss RM, Rotter JI, Nickerson DA, Davis RL, Berg RL, Peissig PL, McCarty CA, Wilke RA, Denny JC. Characterization of statin dose response in electronic medical records. Clin Pharmacol Ther 2013; 95:331-8. [PMID: 24096969 DOI: 10.1038/clpt.2013.202] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 09/25/2013] [Indexed: 01/14/2023]
Abstract
Efforts to define the genetic architecture underlying variable statin response have met with limited success, possibly because previous studies were limited to effect based on a single dose. We leveraged electronic medical records (EMRs) to extract potency (ED50) and efficacy (Emax) of statin dose-response curves and tested them for association with 144 preselected variants. Two large biobanks were used to construct dose-response curves for 2,026 and 2,252 subjects on simvastatin and atorvastatin, respectively. Atorvastatin was more efficacious, was more potent, and demonstrated less interindividual variability than simvastatin. A pharmacodynamic variant emerging from randomized trials (PRDM16) was associated with Emax for both. For atorvastatin, Emax was 51.7 mg/dl in subjects homozygous for the minor allele vs. 75.0 mg/dl for those homozygous for the major allele. We also identified several loci associated with ED50. The extraction of rigorously defined traits from EMRs for pharmacogenetic studies represents a promising approach to further understand the genetic factors contributing to drug response.
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Stevens CW, Aravind S, Das S, Davis RL. Pharmacological characterization of LPS and opioid interactions at the toll-like receptor 4. Br J Pharmacol 2013; 168:1421-9. [PMID: 23083095 DOI: 10.1111/bph.12028] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 10/03/2012] [Accepted: 10/10/2012] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND AND PURPOSE Previous work in our laboratory showed opioid agents inhibit cytokine expression in astrocytes. Recently, Watkins and colleagues hypothesized that opioid agonists activate toll-like receptor 4 (TLR4) signalling, which leads to neuroinflammation. To test this hypothesis, we characterized LPS and opioid effects on TLR4 signalling in reporter cells. EXPERIMENTAL APPROACH NF-κB reporter cells expressing high levels of TLR4 were used to compare LPS and opioid effects on NF-κB activation, a pathway activated by TLR4 stimulation. KEY RESULTS LPS increased TLR4 signalling in a concentration-dependent manner and was antagonized by LPS antagonist (LPS-RS, from Rhodobacter sphaeroides). A concentration ratio analysis showed that LPS-RS was a competitive antagonist. The opioid agonists, morphine and fentanyl, produced minor activation of TLR4 signalling when given alone. When tested following LPS stimulation, opioid agonists inhibited NF-κB activation but this inhibition was not blocked by the general opioid antagonist, naloxone, nor by the selective μ opioid receptor antagonist, β-FNA. Indeed, both naloxone and β-FNA also inhibited NF-κB activation in reporter cells. Further examination of fentanyl and β-FNA effects revealed that both opioid agents inhibited LPS signalling in a non-competitive fashion. CONCLUSIONS AND IMPLICATIONS These results show that LPS-RS is a competitive antagonist at the TLR4 complex, and that both opioid agonists and antagonists inhibit LPS signalling in a non-competitive fashion through a non-GPCR, opioid site(s) in the TLR4 signalling pathway. If confirmed, existing opioid agents or other drug molecules more selective at this novel site may provide a new therapeutic approach to the treatment of neuroinflammation.
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Stocker SL, Morrissey KM, Yee SW, Castro RA, Xu L, Dahlin A, Ramirez AH, Roden DM, Wilke RA, McCarty CA, Davis RL, Brett CM, Giacomini KM. The effect of novel promoter variants in MATE1 and MATE2 on the pharmacokinetics and pharmacodynamics of metformin. Clin Pharmacol Ther 2012; 93:186-94. [PMID: 23267855 DOI: 10.1038/clpt.2012.210] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Interindividual variation in response to metformin, first-line therapy for type 2 diabetes, is substantial. Given that transporters are determinants of metformin pharmacokinetics, we examined the effects of promoter variants in both multidrug and toxin extrusion protein 1 (MATE1) (g.-66T → C, rs2252281) and MATE2 (g.-130G → A, rs12943590) on variation in metformin disposition and response. The pharmacokinetics and glucose-lowering effects of metformin were assessed in healthy volunteers (n = 57) receiving metformin. The renal and secretory clearances of metformin were higher (22% and 26%, respectively) in carriers of variant MATE2 who were also MATE1 reference (P < 0.05). Both MATE genotypes were associated with altered post-metformin glucose tolerance, with variant carriers of MATE1 and MATE2 having an enhanced (P < 0.01) and reduced (P < 0.05) response, respectively. Consistent with these results, patients with diabetes (n = 145) carrying the MATE1 variant showed enhanced metformin response. These findings suggest that promoter variants of MATE1 and MATE2 are important determinants of metformin disposition and response in healthy volunteers and diabetic patients.
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Brennan SO, Oliver J, Davis RL. Epigenetic, polymorphic and mutational (Αα167Arg→Lys) contribution to a functionally abnormal fibrinogen. J Thromb Haemost 2011; 9:1410-2. [PMID: 21605328 DOI: 10.1111/j.1538-7836.2011.04337.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Assefa S, Curtis JT, Sethi S, Davis RL, Chen Y, Kaul R. Inorganic mercury exposure in prairie voles (Microtus ochrogaster) alters the expression of toll-like receptor 4 and activates inflammatory pathways in the liver in a sex-specific manner. Hum Exp Toxicol 2011; 31:376-86. [PMID: 21558144 DOI: 10.1177/0960327111407223] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Environmental exposure to mercury can cause a number of adverse effects in humans including the disruption of endocrine function that may result in sex-specific effects. The present study was designed to characterize sex-specific effects of chronic inorganic mercury exposure on toll-like receptor (TLR) 2 and TLR4 and inflammatory signaling in the liver of prairie voles (Microtus ochrogaster). Following 10 weeks of exposure to mercury via drinking water, effects on protein expression levels of TLR2 and TLR4 and the downstream p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa (NF-κB) signaling pathways were assessed. Using immunoblot analysis, we found that mercury exposure significantly enhanced the expression of TLR4 and activated p38 MAPK and NF-κB pathways in vole livers. This is the first report indicating that TLR4 may serve as a sensor for chronic mercury exposure in the liver. Further, compared to females, mercury-treated male voles exhibited significant increases in activated p38 MAPK and a greater extent of liver damage. Together, these findings establish sex-specific liver immunomodulation and cellular signaling following chronic inorganic mercury exposure. Furthermore, this study also supports the use of voles as biomarkers of environmental mercury contamination and offers a promising in vivo tool to test various therapeutic strategies for mercury detoxification.
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Wilke RA, Xu H, Denny JC, Roden DM, Krauss RM, McCarty CA, Davis RL, Skaar T, Lamba J, Savova G. The emerging role of electronic medical records in pharmacogenomics. Clin Pharmacol Ther 2011; 89:379-86. [PMID: 21248726 DOI: 10.1038/clpt.2010.260] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Health-care information technology and genotyping technology are both advancing rapidly, creating new opportunities for medical and scientific discovery. The convergence of these two technologies is now facilitating genetic association studies of unprecedented size within the context of routine clinical care. As a result, the medical community will soon be presented with a number of novel opportunities to bring functional genomics to the bedside in the area of pharmacotherapy. By linking biological material to comprehensive medical records, large multi-institutional biobanks are now poised to advance the field of pharmacogenomics through three distinct mechanisms: (i) retrospective assessment of previously known findings in a clinical practice-based setting, (ii) discovery of new associations in huge observational cohorts, and (iii) prospective application in a setting capable of providing real-time decision support. This review explores each of these translational mechanisms within a historical framework.
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Brennan SO, Davis RL, Lowen R, Baker B. Benign substitution (Aα289 Arg→Gln) in the αC region of human fibrinogen. Blood Cells Mol Dis 2010; 45:336-7. [PMID: 20870435 DOI: 10.1016/j.bcmd.2010.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 08/16/2010] [Accepted: 08/16/2010] [Indexed: 10/19/2022]
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Brennan SO, Davis RL, Conard K, Savo A, Furuya KN. Novel fibrinogen mutation γ314Thr→Pro (fibrinogen AI duPont) associated with hepatic fibrinogen storage disease and hypofibrinogenaemia. Liver Int 2010; 30:1541-7. [PMID: 20666993 DOI: 10.1111/j.1478-3231.2010.02312.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Mutation in fibrinogen genes may lead to quantitative or qualitative disorders that result in bleeding, thrombosis or hepatic fibrinogen storage disease. Only three mutations in the fibrinogen γ gene have been identified that cause hepatic endoplasmic reticulum storage of mutant fibrinogen. To investigate the possibility of hepatic fibrinogen storage disease in a 4-year-old male with persistently elevated serum aminotransferases and preserved synthetic function except for a prolonged INR. After informed consent, liver and blood samples were obtained. Liver sections were examined by light microscopy, anti-fibrinogen immunolabelling and electron microscopy. Purified fibrinogen was analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and reverse phase high performance liquid chromatography; DNA sequencing was performed using a BigDye Terminator (v. 3.1) cycle sequencing kit. Four-year-old male with persistently elevated transaminases with an INR 1.5 but otherwise normal synthetic function. Fibrinogen activity and thrombin clotting time were abnormal at 0.47 g/L and 46 s respectively. Hepatic histological examination revealed portal inflammatory infiltrates with bridging fibrosis. Clumped eosinophilic material was observed in hepatocytes that was immunoreactive to fibrinogen antisera. Ultrastructural examination showed cytoplasmic inclusions arrayed in fingerprint-like patterns. DNA sequence analysis revealed heterozygosity for a novel γ314Thr →Pro mutation (fibrinogen AI duPont) in the fibrinogen γ gene. Protein analyses showed normal patterns of Aα, Bβ and γ chains suggesting that the variant γ allele was not expressed in plasma fibrinogen. We describe only the fourth mutation to be identified, γ314Thr→Pro (fibrinogen AI duPont), giving rise to hypofibrinogenaemia and hepatic fibrinogen storage disease.
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Davis RL, Chow BF. Some Applications of the Rapid Uptake of Vitamin B12 by Resting Lactobacillus leichmannii Organisms. Science 2010; 115:351-2. [PMID: 17748850 DOI: 10.1126/science.115.2987.351] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Ahlin G, Chen L, Lazorova L, Chen Y, Ianculescu AG, Davis RL, Giacomini KM, Artursson P. Genotype-dependent effects of inhibitors of the organic cation transporter, OCT1: predictions of metformin interactions. THE PHARMACOGENOMICS JOURNAL 2010; 11:400-11. [PMID: 20567254 DOI: 10.1038/tpj.2010.54] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Common genetic variants of the liver-specific human organic cation transporter 1 (OCT1; SLC22A1) have reduced transport capacity for substrates such as the antidiabetic drug metformin. The effect of the reduced OCT1 function on drug interactions associated with OCT1 has not been investigated and was, therefore, the focus of the study presented here. HEK293 cells expressing human OCT1-reference or the variants R61C, V408M, M420del and G465R were first used to study the kinetics and inhibition pattern of the OCT1 substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium (ASP(+)). In the second part OCT1-mediated (14)C-metformin uptake was studied in the presence of drugs administered concomitantly with metformin. Transport studies using ASP(+) showed that the function of the variants decreased in the following order: OCT1-reference=V408M=M420del >R61C >>G465R. Variants M420del and R61C were more sensitive to drug inhibition, with IC(50) values up to 23 times lower than those of the OCT1-reference. Uptake studies using (14)C-metformin were in qualitative agreement with those using ASP(+), with the exception that a larger reduction in transport capacity was observed for M420del. Concomitantly administered drugs, such as verapamil and amitriptyline, revealed potential drug-drug interactions at clinical plasma concentrations of metformin for OCT1-M420del.
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Chan CS, Chen H, Bradley A, Dragatsis I, Rosenmund C, Davis RL. α8-integrins are required for hippocampal long-term potentiation but not for hippocampal-dependent learning. GENES BRAIN AND BEHAVIOR 2010; 9:402-10. [PMID: 20132319 DOI: 10.1111/j.1601-183x.2010.00569.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Integrins are heterodimeric transmembrane cell adhesion receptors that are essential for a wide range of biological functions via cell-matrix and cell-cell interactions. Recent studies have provided evidence that some of the subunits in the integrin family are involved in synaptic and behavioral plasticity. To further understand the role of integrins in the mammalian central nervous system, we generated a postnatal forebrain and excitatory neuron-specific knockout of alpha8-integrin in the mouse. Behavioral studies showed that the mutant mice are normal in multiple hippocampal-dependent learning tasks, including a T-maze, non-match-to-place working memory task for which other integrin subunits like alpha3- and beta1-integrin are required. In contrast, mice mutant for alpha8-integrin exhibited a specific impairment of long-term potentiation (LTP) at Schaffer collateral-CA1 synapses, whereas basal synaptic transmission, paired-pulse facilitation and long-term depression (LTD) remained unaffected. Because LTP is also impaired in the absence of alpha3-integrin, our results indicate that multiple integrin molecules are required for the normal expression of LTP, and different integrins display distinct roles in behavioral and neurophysiological processes like synaptic plasticity.
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Brennan SO, Davis RL, Chitlur M. New fibrinogen substitution (gammaSer313Arg) causes diminished gamma chain expression and hypodysfibrinogenaemia. Thromb Haemost 2009; 103:478-9. [PMID: 20126833 DOI: 10.1160/th09-07-0459] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 10/10/2009] [Indexed: 11/05/2022]
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Davis RL, May S, Chunilal S, Brennan SO. Two novel mutations at contiguous codons in the fibrinogen Bbeta chain associated with hypofibrinogenaemia. Thromb Haemost 2009; 101:980-982. [PMID: 19404555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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Davis RL, Homer VM, George PM, Brennan SO. A deep intronic mutation in FGB creates a consensus exonic splicing enhancer motif that results in afibrinogenemia caused by aberrant mRNA splicing, which can be corrected in vitro with antisense oligonucleotide treatment. Hum Mutat 2009; 30:221-7. [PMID: 18853456 DOI: 10.1002/humu.20839] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We previously described a novel homozygous point mutation (FGB c.115-600A>G) located deep within intron 1 of the fibrinogen beta gene (FGB), as a likely cause of afibrinogenemia. While this was the only mutation detected, its pathological mechanism was unclear. Here we show the mutation causes the inclusion of a 50-bp cryptic exon by creating a consensus heptad motif recognized by the spliceosome recruiting protein pre-mRNA splicing factor (SF2)/arginine/serine-rich alternative splicing factor (ASF) splicing factor 2/alternative splicing factor (SF2/ASF). Translation of the aberrant mRNA would result in truncation of the Bbeta chain, preventing fibrinogen synthesis. Selective introduction of a second mutation into the enhancer motif abolished the SF2/ASF binding motif and re-established normal pre-mRNA splicing. Subsequent introduction of antisense phosphorodiamidate morpholino oligonucleotides (PMOs) into transfected cells containing the mutant construct blocked the protein-RNA interaction and successfully restored normal splicing ( approximately 50% at 2 microM and approximately 90% at 10 microM). The molecular characterization of this case has revealed a unique disease mechanism, shown the importance of screening for deep intronic mutations, and provided evidence that antisense gene therapy is potentially practical for the treatment of diseases caused by this class of mutation.
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Brennan SO, Davis RL, Lowen R, Ruskova A. Deletion of five residues from the coiled coil of fibrinogen (Bbeta Asn167_Glu171del) associated with bleeding and hypodysfibrinogenemia. Haematologica 2009; 94:585-8. [PMID: 19229055 DOI: 10.3324/haematol.2008.001412] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Routine pre-surgical coagulation investigations led to the detection of a novel type of hypodysfibrinogenemia whose functional defect appears to result from an alteration in the spacing between the functional domains of the fibrinogen molecule. The detection, by reverse phase HPLC, of a minor isoform of Bbeta chain with a 554 Da decrease in mass led to the identification of a deletion of five amino acids (NVVNE) from the center of the coiled coil. The variant chain contributed only 10% of the total Bbeta material and the mutation (BbetaAsn167_Glu171del) was associated with both increased clotting times and low functional and physical fibrinogen concentrations in 3 family members. There was a significant history of pregnancy-associated bleeding and miscarriage within the first trimester. Mechanistically the 15-nucleotide deletion appears to arise from replication advancement during DNA synthesis caused by a flanking pentanucleotide repeat of AATGA.
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Davis RL, Baker B, Brennan SO. Fibrinogen Foxton: a novel BbetaA277V mutation causing low normal plasma fibrinogen concentration. Thromb Haemost 2008; 100:708-710. [PMID: 18841297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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Baker B, Brennan SO, Davis RL. Fibrinogen Foxton: A novel BβA277V mutation causing low normal plasma fibrinogen concentration. Thromb Haemost 2008. [DOI: 10.1160/th08-05-0304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Davis RL, Brennan SO. Fibrinogen Tolaga Bay: a novel gammaAla341Val mutation causing hypofibrinogenaemia. Thromb Haemost 2007; 98:1136-1138. [PMID: 18000621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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Brennan SO, Davis RL, Mosesson MW, Hernandez I, Lowen R, Alexander SJ. Congenital hypodysfibrinogenaemia (Fibrinogen Des Moines) due to a gamma320Asp deletion at the Ca2+ binding site. Thromb Haemost 2007; 98:467-9. [PMID: 17721633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
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Davis RL, Mosesson MW, Kerlin BA, Canner JA, Ruymann FB, Brennan SO. Fibrinogen Columbus: a novel gamma Gly200Val mutation causing hypofibrinogenemia in a family with associated thrombophilia. Haematologica 2007; 92:1151-2. [PMID: 17650452 DOI: 10.3324/haematol.11235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Fibrinogen is an essential component of the coagulation cascade and the acute phase response. The native 340 kDa molecule has a symmetrical trinodular structure composed of a central E-domain connected to outer D-domains by triple helical coiled-coils.1 Several mutations known to cause hypofibrinogenemia occur within the C-terminal gammaD-domain and have helped to elucidate the structurally and functionally important areas of this domain.2-5 Here we report the identification of a novel point mutation gammaG200V (fibrinogen Columbus) causing hypofibrinogenemia and co-segregating with three genetic thrombophilia risk factors.
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Brennan SO, Homer VM, Davis RL, Meyer M, George PM. Hypofibrinogenaemia associated with common gamma82Ala-->Gly mutation is not mediated by altered mRNA splicing. Thromb Haemost 2006; 96:535-7. [PMID: 17003934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
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Dulon D, Jagger DJ, Lin X, Davis RL. Neuromodulation in the Spiral Ganglion: Shaping Signals from the Organ of Corti to the CNS. J Membr Biol 2006; 209:167-75. [PMID: 16773500 DOI: 10.1007/s00232-005-0841-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Indexed: 11/25/2022]
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Kokay IC, Bull PM, Davis RL, Ludwig M, Grattan DR. Expression of the long form of the prolactin receptor in magnocellular oxytocin neurons is associated with specific prolactin regulation of oxytocin neurons. Am J Physiol Regul Integr Comp Physiol 2006; 290:R1216-25. [PMID: 16410399 DOI: 10.1152/ajpregu.00730.2005] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Magnocellular neurons of the supraoptic (SON) and paraventricular nuclei (PVN) show considerable plasticity during pregnancy and lactation. Prolactin receptors (PRL-R) have been identified in both these nuclei. The aim of this study was to investigate the cell type(s) expressing mRNA for the long form of prolactin receptor (PRL-RL) and to determine whether patterns of expression change during pregnancy and lactation. In addition, we examined effects of prolactin on excitability of oxytocin and vasopressin neurons. Sections from brains of nonpregnant, pregnant, and lactating rats were hybridized with an 35S-labeled probe to label PRL-RL mRNA together with digoxigenin-labeled probes to detect either oxytocin or vasopressin mRNA. In the SON, PRL-RL mRNA was predominantly colocalized with oxytocin mRNA, with over 80% of oxytocin neurons positive for PRL-RL mRNA. Very few (<10%) vasopressin neurons expressed PRL-RL mRNA. In the PVN, PRL-RL mRNA was also predominantly found in oxytocin neurons, and the proportion of PRL-RL-positive oxytocin neurons increased significantly during pregnancy and lactation. As in the SON, relatively few vasopressin cells contained PRL-RL mRNA. For in vivo electrophysiology, nonpregnant rats were anesthetized, and then extracellular single neuron activity was recorded in identified oxytocin and vasopressin neurons. After a period of baseline recording, the effect of prolactin (1 μg icv) on firing rate was examined. Prolactin treatment of nonpregnant rats induced a significant decrease in firing rates of oxytocin neurons. There was no effect of prolactin on the activity of vasopressin neurons. Together, these data provide strong evidence that prolactin directly and specifically regulates activity of oxytocin neurons.
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Schold SC, Kokkinakis DM, Chang SM, Berger MS, Hess KR, Schiff D, Robins HI, Mehta MP, Fink KL, Davis RL, Prados MD. O6-benzylguanine suppression of O6-alkylguanine-DNA alkyltransferase in anaplastic gliomas. Neuro Oncol 2004; 6:28-32. [PMID: 14769137 PMCID: PMC1871964 DOI: 10.1215/s115285170300019x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The purpose of the study was to determine the dose of O(6)-benzylguanine (BG) that would suppress O(6)-alkylguanine-DNA alkyltransferase (AGT) activity to undetectable levels in > 90% of anaplastic gliomas, as measured 6 h after a 1-h BG infusion. Subjects who were scheduled for surgical resection of a known or presumed anaplastic glioma received a 1-h infusion of BG. Tumor tissue was surgically removed approximately 6 h after the end of the infusion and was analyzed for AGT activity. The BG dose was escalated until at least 11 of 14 subjects had no detectable AGT activity. An additional cohort of patients received the identified effective dose of BG approximately 18 h before tumor resection in order to compare our results with an earlier study using the longer time interval. In the 79 subjects who were enrolled, there was no significant toxicity that was attributed to the BG. A dose-response relationship was determined between the BG dose and the percentage of subjects with undetectable AGT. A dose of 120 mg/m(2) suppressed AGT to less than detectable levels in 17 of 18 patients when the drug-resection interval was 6 h. With an 18-h interval, only 5 of 11 subjects had undetectable AGT at the 120-mg/m(2) dose. We conclude that a BG dose of 120 mg/m(2) given 6 h before an alkylating drug would be effective in suppressing AGT and possibly potentiating the cytotoxic effects of the drug.
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