Recent Research Articles from UNTHSC

Recent research articles indexed in PubMed from authors affiliated with the UNT Health Science Center.

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The dual modulatory effects of efavirenz on GABAA receptors are mediated via two distinct sites.

Mon, 05/01/2017 - 07:36
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The dual modulatory effects of efavirenz on GABAA receptors are mediated via two distinct sites.

Neuropharmacology. 2017 Apr 26;:

Authors: Huang R, Chen Z, Dolan S, Schetz JA, Dillon GH

Abstract
Efavirenz is a widely prescribed medicine used to treat type 1 human immunodeficiency virus (HIV-1), the most prevalent pathogenic strain of the virus responsible for the acquired immune deficiency syndrome (AIDS) pandemic. Under prescribed dosing conditions, either alone or in combination therapy, efavirenz-induced CNS disturbances are frequently reported. Efavirenz was recently reported to interact in a similar concentration range with a number of receptors, transporters and ion channels including recombinant rat α1β2γ2 GABAA receptors whose actions were potentiated (Gatch et al., 2013; Dalwadi et al., 2016). Now we report on the molecular mechanism of efavirenz on GABAA receptors as a function of concentration and subunit composition via whole-cell recordings of GABA-activated currents from HEK293 cells expressing varying subunit configurations of GABAA receptors. Efavirenz elicited dual effects on the GABA response; it allosterically potentiated currents at low concentrations, whereas it inhibited currents at higher concentrations. The allosteric potentiating action on GABAA receptors was pronounced in the α1β2γ2, α2β2γ2 and α4β2γ2 configurations, greatly diminished in the α6β2γ2 configuration, and completely absent in the α3β2γ2 or α5β2γ2 configuration. In stark contrast, the inhibitory modulation of efavirenz at higher concentrations was evident in all subunit configurations examined. Moreover, efavirenz-induced modulatory effects were dependent on GABA concentration ([GABA]), with a pronounced impact on currents activated by low [GABA] but little effect at saturating [GABA]. Mutation of a highly-conserved threonine to phenylalanine in transmembrane domain 2 of the α1 subunit abolished the inhibitory effect of efavirenz in α1β2 receptors. Finally, mutations of any of the three conserved extracellular residues in α1/2/4 subunits to the conserved residues at the corresponding positions in α3/5 subunits (i.e., R84P, M89L or I120L) completely eliminated he potentiating effect of efavirenz in α1β2γ2 configuration. These findings demonstrate that efavirenz's positive allosteric modulation of the GABAA receptor is mediated via a novel allosteric site associated with the extracellular domain of the receptor.

PMID: 28456686 [PubMed - as supplied by publisher]

Genome Sequence of a Providencia stuartii Strain Isolated from Luciliasericata Salivary Glands.

Sun, 04/30/2017 - 07:32
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Genome Sequence of a Providencia stuartii Strain Isolated from Luciliasericata Salivary Glands.

Genome Announc. 2017 Apr 27;5(17):

Authors: Yuan Y, Zhang Y, Fu S, Crippen TL, Visi DK, Benbow ME, Allen MS, Tomberlin JK, Sze SH, Tarone AM

Abstract
We present here the draft genome sequence of a Providencia stuartii strain, derived from the salivary glands of larval Lucilia sericata, a common blow fly important to forensic, medical, and veterinary science. The genome sequence will help dissect coinfections involving P. stuartii and Proteus mirabilis, as well as blow fly-bacteria interactions.

PMID: 28450516 [PubMed - in process]

Antibacterial activity of the novel semisynthetic lantibiotic NVB333 in vitro and in experimental infection models.

Wed, 04/26/2017 - 07:36
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Antibacterial activity of the novel semisynthetic lantibiotic NVB333 in vitro and in experimental infection models.

J Antibiot (Tokyo). 2016 Dec;69(12):850-857

Authors: Boakes S, Weiss WJ, Vinson M, Wadman S, Dawson MJ

Abstract
NVB333 is a novel semisynthetic lantibiotic derived from the amide coupling of 3,5-dichlorobenzylamine to the C-terminal of deoxyactagardine B. The in vitro activity of NVB333 includes efficacy against clinically relevant pathogens including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus spp. NVB333 shows no cross-resistance with other antibiotics tested and a very low propensity for resistance development. After intravenous dosing NVB333 has high exposure in mouse plasma and shows generally improved in vivo activity compared with vancomycin in mouse infection models despite modest MIC values. In thigh infection models, promising efficacy was demonstrated against several strains of S. aureus including methicillin-resistant S. aureus (MRSA) and vancomycin-intermediate S. aureus (VISA) strains, and against Enterococcus faecalis UNT126-3. Area under the concentration curve (AUC)/MIC was shown to be the best predictor of efficacy against S. aureus UNT103-3 with an AUC/MIC of 138 (uncorrected for protein binding) achieving a static effect. NVB333 was also effective in a disseminated infection model where it conferred complete survival from the MRSA strain ATCC 33591. NVB333 showed rather modest lung penetration after intravenous dosing (AUC in lung 2-3% of plasma AUC), but because of very high plasma exposure, therapeutic levels of compound were achieved in the lung. Efficacy at least equal to vancomycin was demonstrated against an MRSA strain (UNT084-3) in a bronchoalveolar infection model. The impressive in vivo efficacy of NVB333 and strong resistance prognosis makes this compound an interesting candidate for development for treating systemic Gram-positive infections.

PMID: 27189121 [PubMed - indexed for MEDLINE]

Tip110 Deletion Impaired Embryonic And Stem Cell Development Involving Down-Regulation Of Stem Cell Factors Nanog, Oct4 And Sox2.

Tue, 04/25/2017 - 07:38
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Tip110 Deletion Impaired Embryonic And Stem Cell Development Involving Down-Regulation Of Stem Cell Factors Nanog, Oct4 And Sox2.

Stem Cells. 2017 Apr 24;:

Authors: Whitmill A, Liu Y, Timani KA, Niu Y, He JJ

Abstract
HIV-1 Tat-interacting protein of 110 kDa, Tip110, plays important roles in multiple biological processes. In this study, we aimed to characterize the function of Tip110 in embryonic development. Transgenic mice lacking expression of a functional Tip110 gene (Tip110(-/-) ) died post-implantation, and Tip110(-/-) embryos exhibited developmental arrest between 8.5 and 9.5 days post coitum. However, in vitro cultures of Tip110(-/-) embryos showed that Tip110 loss did not impair embryo growth from the zygote to the blastocyst. Extended in vitro cultures of Tip110(-/-) blastocysts showed that Tip110 loss impaired both blastocyst outgrowth and self-renewal and survival of blastocyst-derived embryonic stem cells. Microarray analysis of Tip110(-/-) embryonic stem cells revealed that Tip110 loss altered differentiation, pluripotency, and cycling of embryonic stem cells and was associated with down-regulation of several major stem cell factors including Nanog, Oct4, and Sox2 through a complex network of signaling pathways. Taken together, these findings document for the first time the lethal effects of complete loss of Tip110 on mammalian embryonic development and suggest that Tip110 is an important regulator of not only embryonic development but also stem cell factors. This article is protected by copyright. All rights reserved.

PMID: 28436127 [PubMed - as supplied by publisher]

Tryptophan Fluorescence Yields and Lifetimes as a Probe of Conformational Changes in Human Glucokinase.

Sun, 04/23/2017 - 07:33
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Tryptophan Fluorescence Yields and Lifetimes as a Probe of Conformational Changes in Human Glucokinase.

J Fluoresc. 2017 Apr 22;:

Authors: Zelent B, Bialas C, Gryczynski I, Chen P, Chib R, Lewerissa K, Corradini MG, Ludescher RD, Vanderkooi JM, Matschinsky FM

Abstract
Five variants of glucokinase (ATP-D-hexose-6-phosphotransferase, EC 2.7.1.1) including wild type and single Trp mutants with the Trp residue at positions 65, 99, 167 and 257 were prepared. The fluorescence of Trp in all locations studied showed intensity changes when glucose bound, indicating that conformational change occurs globally over the entire protein. While the fluorescence quantum yield changes upon glucose binding, the enzyme's absorption spectra, emission spectra and fluorescence lifetimes change very little. These results are consistent with the existence of a dark complex for excited state Trp. Addition of glycerol, L-glucose, sucrose, or trehalose increases the binding affinity of glucose to the enzyme and increases fluorescence intensity. The effect of these osmolytes is thought to shift the protein conformation to a condensed, high affinity form. Based upon these results, we consider the nature of quenching of the Trp excited state. Amide groups are known to quench indole fluorescence and amides of the polypeptide chain make interact with excited state Trp in the relatively unstructured, glucose-free enzyme. Also, removal of water around the aromatic ring by addition of glucose substrate or osmolyte may reduce the quenching.

PMID: 28432632 [PubMed - as supplied by publisher]

Effect of short-term DHEA supplementation on serum and hippocampal estrogen concentrations in perimenopausal female rhesus macaques.

Sun, 04/23/2017 - 07:33
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Effect of short-term DHEA supplementation on serum and hippocampal estrogen concentrations in perimenopausal female rhesus macaques.

Neurobiol Aging. 2017 Mar 31;:

Authors: Urbanski HF, Sorwell KG, Prokai L, Kohama SG

Abstract
The hippocampus of rhesus macaques expresses genes that encode key enzymes involved in the intracrine conversion of dehydroepiandrosterone (DHEA) to estradiol. Therefore, it is plausible that supplementary DHEA may enhance hippocampal estradiol concentrations and help to compensate for the marked postmenopausal attenuation of circulating estrogen levels. To test this hypothesis, we used LC-MS/MS to measure estradiol and estrone concentrations in the serum and hippocampus of young and old perimenopausal female rhesus macaques, as well as old perimenopausal females that received daily DHEA (5 mg) oral supplementation for 1 week. Despite lower concentrations of these estrogens in the serum of the older animals, their concentrations in the hippocampus did not show any obvious differences due to age or to DHEA supplementation. The results suggest that de novo estrogen synthesis in the brain may compensate for the perimenopausal loss of estrogens in the circulation even without supplemental DHEA.

PMID: 28431754 [PubMed - as supplied by publisher]

Erratum to: More Comprehensive Forensic Genetic Marker Analyses for Accurate Human Remains Identification Using Massively Parallel DNA Sequencing.

Sat, 04/22/2017 - 07:43
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Erratum to: More Comprehensive Forensic Genetic Marker Analyses for Accurate Human Remains Identification Using Massively Parallel DNA Sequencing.

BMC Genomics. 2017 Apr 20;18(1):312

Authors: Ambers AD, Churchill JD, King JL, Stoljarova M, Gill-King H, Assidi M, Abu-Elmagd M, Buhmeida A, Al-Qahtani M, Budowle B

PMID: 28427331 [PubMed - in process]

Caspase-3-Dependent Proteolytic Cleavage of Tau Causes Neurofibrillary Tangles and Results in Cognitive Impairment During Normal Aging.

Tue, 04/18/2017 - 07:32
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Caspase-3-Dependent Proteolytic Cleavage of Tau Causes Neurofibrillary Tangles and Results in Cognitive Impairment During Normal Aging.

Neurochem Res. 2016 Sep;41(9):2278-88

Authors: Means JC, Gerdes BC, Kaja S, Sumien N, Payne AJ, Stark DA, Borden PK, Price JL, Koulen P

Abstract
Mouse models of neurodegenerative diseases such as Alzheimer's disease (AD) are important for understanding how pathological signaling cascades change neural circuitry and with time interrupt cognitive function. Here, we introduce a non-genetic preclinical model for aging and show that it exhibits cleaved tau protein, active caspases and neurofibrillary tangles, hallmarks of AD, causing behavioral deficits measuring cognitive impairment. To our knowledge this is the first report of a non-transgenic, non-interventional mouse model displaying structural, functional and molecular aging deficits associated with AD and other tauopathies in humans with potentially high impact on both new basic research into pathogenic mechanisms and new translational research efforts. Tau aggregation is a hallmark of tauopathies, including AD. Recent studies have indicated that cleavage of tau plays an important role in both tau aggregation and disease. In this study we use wild type mice as a model for normal aging and resulting age-related cognitive impairment. We provide evidence that aged mice have increased levels of activated caspases, which significantly correlates with increased levels of truncated tau and formation of neurofibrillary tangles. In addition, cognitive decline was significantly correlated with increased levels of caspase activity and tau truncated by caspase-3. Experimentally induced inhibition of caspases prevented this proteolytic cleavage of tau and the associated formation of neurofibrillary tangles. Our study shows the strength of using a non-transgenic model to study structure, function and molecular mechanisms in aging and age related diseases of the brain.

PMID: 27220334 [PubMed - indexed for MEDLINE]

Effects of low-dose aspirin on maternal blood pressure and vascular function in an experimental model of gestational hypertension.

Mon, 04/17/2017 - 07:39

Effects of low-dose aspirin on maternal blood pressure and vascular function in an experimental model of gestational hypertension.

Pharmacol Res. 2017 Apr 12;:

Authors: Osikoya O, Jaini PA, Nguyen A, Valdes M, Goulopoulou S

Abstract
Daily intake of low-dose aspirin after 12weeks of gestation is currently recommended as a preventative intervention in pregnancies in high risk of developing preeclampsia. This recommendation is based on epidemiological evidence, whereas experimental studies investigating the exact mechanisms of aspirin action during pregnancy are lacking. We previously showed that treating pregnant rats with a synthetic mimetic of unmethylated CpG DNA (bacterial DNA) caused preeclampsia-like characteristics such as maternal hypertension and increased cyclooxygenase (COX) expression and activity. In this study, we tested the hypothesis that daily maternal treatment with low-dose aspirin would prevent the development of maternal hypertension, reduce COX activity and thromboxane A2 (TxA2) production, and improve maternal vascular function in pregnant rats exposed to CpG ODN during gestation. Pregnant rats were treated with ODN2395 (synthetic CpG DNA) or saline (vehicle) on gestational days (GD) 14, 16, 18. Daily low-dose aspirin treatment (1.5mg/kgBW) started on GD10 and continued throughout gestation. Pregnant rats treated with ODN2395 had greater systolic blood pressure compared to controls (120±4mmHg vs. 100±5mmHg, p=0.03) and aspirin did not prevent this increase (p=0.86). Aspirin prevented ODN2395-induced increases of TxB2 (TxA2 metabolite) in serum and mesenteric arteries. ODN2395 increased expression of COX-1 and COX-2 in mesenteric and uterine arteries and aspirin abolished these effects. Aspirin reduced contractile responses to phenylephrine and U46619 (TxA2 mimetic) in mesenteric arteries from control rats but not from ODN2395-treated rats. In conclusion, treatment with low-dose aspirin reduced systemic and vascular COX expression and activity but did not prevent the development of maternal hypertension induced by exposure to unmethylated CpG DNA (bacterial DNA).

PMID: 28412461 [PubMed - as supplied by publisher]

Parent and Health Care Provider Perceptions for Development of a Web-Based Weight Management Program for Survivors of Pediatric Acute Lymphoblastic Leukemia: A Mixed Methods Study.

Sat, 04/15/2017 - 07:35

Parent and Health Care Provider Perceptions for Development of a Web-Based Weight Management Program for Survivors of Pediatric Acute Lymphoblastic Leukemia: A Mixed Methods Study.

JMIR Cancer. 2017 Feb 09;3(1):e2

Authors: Folta S, Chang W, Hill R, Kelly M, Meagher S, Bowman WP, Zhang FF

Abstract
BACKGROUND: Survivors of pediatric acute lymphoblastic leukemia (ALL) may experience unhealthy weight gain during treatment, which has been associated with higher risk for chronic health issues.
OBJECTIVE: The purpose of this study was to obtain feedback on weight management in pediatric ALL survivors and on the content and implementation of a Web-based weight management program.
METHODS: Study participants included 54 parent survey respondents and 19 pediatric oncology professionals in 4 focus groups. Survey questions included report of child weight status and interest in participating in weight management programming at various time points. Pediatric oncology professionals were asked about the preferred topics and timing, as well as their role. Focus group data were analyzed by a multidisciplinary research team for common themes.
RESULTS: The mean age of survivors was 6.5 years. By parent report, 19% of children were overweight and 25% were obese. Preferred timing for weight management program participation was within 3 months of starting maintenance chemotherapy (23/53, 43%) or within 12 months after completion of all cancer treatments (18/53, 34%). Pediatric oncology professionals likewise considered the maintenance phase appropriate. They considered parenting to be an important topic to include and indicated that their most appropriate roles would be promotion and support.
CONCLUSIONS: Parents and pediatric oncology professionals are interested in and supportive of early weight management in pediatric ALL survivors. Future research needs to identify strategies to integrate this into pediatric cancer care and to evaluate the feasibility and efficacy of these strategies.

PMID: 28410182 [PubMed - in process]

Comments on 'A note on the variance of the estimate of the fixation index F'.

Sat, 04/15/2017 - 07:35
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Comments on 'A note on the variance of the estimate of the fixation index F'.

J Genet. 2016 06;95(2):229-30

Authors: Chakraborty R

PMID: 27350663 [PubMed - indexed for MEDLINE]

Combining Injectable Plasma Scaffold with Mesenchymal Stem/Stromal Cells for Repairing Infarct Cavity after Ischemic Stroke.

Thu, 04/13/2017 - 07:34
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Combining Injectable Plasma Scaffold with Mesenchymal Stem/Stromal Cells for Repairing Infarct Cavity after Ischemic Stroke.

Aging Dis. 2017 Apr;8(2):203-214

Authors: Zhang H, Sun F, Wang J, Xie L, Yang C, Pan M, Shao B, Yang GY, Yang SH, ZhuGe Q, Jin K

Abstract
Stroke survivors are typically left with structural brain damage and associated functional impairment in the chronic phase of injury, for which few therapeutic options exist. We reported previously that transplantation of human embryonic stem cell (hESC)-derived neural stem cells together with Matrigel scaffolding into the brains of rats after focal ischemia reduced infarct volume and improved neurobehavioral performance. Matrigel is a gelatinous protein mixture extracted from mouse sarcoma cells, thus would not be approved for use as a scaffold clinically. In this study, we generated a gel-like scaffold from plasma that was controlled by changing the concentration of CaCl2. In vitro study confirmed that 10-20 mM CaCl2 and 10-40% plasma did not affect the viability and proliferation of human and rat bone marrow mesenchymal stem/stromal cells (BMSCs) and neural stem cells (NSCs). We transplanted plasma scaffold in combination of BMSCs into the cystic cavity after focal cerebral ischemia, and found that the atrophy volume was dramatically reduced and motor function was significantly improved in the group transplanted with scaffold/BMSCs compared with the groups treated with vehicle, scaffold or BMSCs only. Our data suggest that plasma-derived scaffold in combination of BMSCs is feasible for tissue engineering approach for the stroke treatment.

PMID: 28400986 [PubMed]

Salvianolic Acid B (Sal B) Protects Retinal Pigment Epithelial Cells from Oxidative Stress-Induced Cell Death by Activating Glutaredoxin 1 (Grx1).

Thu, 04/13/2017 - 07:34
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Salvianolic Acid B (Sal B) Protects Retinal Pigment Epithelial Cells from Oxidative Stress-Induced Cell Death by Activating Glutaredoxin 1 (Grx1).

Int J Mol Sci. 2016 Nov 03;17(11):

Authors: Liu X, Xavier C, Jann J, Wu H

Abstract
Protein glutathionylation, defined as the formation of protein mixed disulfides (PSSG) between cysteine residues and glutathione (GSH), can lead to cell death. Glutaredoxin 1 (Grx1) is a thiol repair enzyme which catalyzes the reduction of PSSG. Therefore, Grx1 exerts strong anti-apoptotic effects by improving the redox state, especially in times of oxidative stress. However, there is currently no compound that is identified as a Grx1 activator. In this study, we identified and characterized Salvianolic acid B (Sal B), a natural compound, as a Grx1 inducer, which potently protected retinal pigment epithelial (RPE) cells from oxidative injury. Our results showed that treatment with Sal B protected primary human RPE cells from H₂O₂-induced cell damage. Interestingly, we found Sal B pretreatment upregulated Grx1 expression in RPE cells in a time- and dose-dependent manner. Furthermore, NF-E2-related factor 2 (Nrf2), the key transcription factor that regulates the expression of Grx1, was activated in Sal B treated RPE cells. Further investigation showed that knockdown of Grx1 by small interfering RNA (siRNA) significantly reduced the protective effects of Sal B. We conclude that Sal B protects RPE cells against H₂O₂-induced cell injury through Grx1 induction by activating Nrf2 pathway, thus preventing lethal accumulation of PSSG and reversing oxidative damage.

PMID: 27827892 [PubMed - indexed for MEDLINE]

Global genetic variation of select opiate metabolism genes in self-reported healthy individuals.

Wed, 04/12/2017 - 07:36
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Global genetic variation of select opiate metabolism genes in self-reported healthy individuals.

Pharmacogenomics J. 2017 Apr 11;:

Authors: Wendt FR, Pathak G, Sajantila A, Chakraborty R, Budowle B

Abstract
CYP2D6 is a key pharmacogene encoding an enzyme impacting poor, intermediate, extensive and ultrarapid phase I metabolism of many marketed drugs. The pharmacogenetics of opiate drug metabolism is particularly interesting due to the relatively high incidence of addiction and overdose. Recently, trans-acting opiate metabolism and analgesic response enzymes (UGT2B7, ABCB1, OPRM1 and COMT) have been incorporated into pharmacogenetic studies to generate more comprehensive metabolic profiles of patients. With use of massively parallel sequencing, it is possible to identify additional polymorphisms that fine tune, or redefine, previous pharmacogenetic findings, which typically rely on targeted approaches. The 1000 Genomes Project data were analyzed to describe population genetic variation and statistics for these five genes in self-reported healthy individuals in five global super- and 26 sub-populations. Findings on the variation of these genes in various populations expand baseline understanding of pharmacogenetically relevant polymorphisms for future studies of affected cohorts.The Pharmacogenomics Journal advance online publication, 11 April 2017; doi:10.1038/tpj.2017.13.

PMID: 28398354 [PubMed - as supplied by publisher]

Development and validation of a novel multiplexed DNA analysis system, InnoTyper(®) 21.

Mon, 04/10/2017 - 07:33
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Development and validation of a novel multiplexed DNA analysis system, InnoTyper(®) 21.

Forensic Sci Int Genet. 2017 Mar 18;29:80-99

Authors: Brown H, Thompson R, Murphy G, Peters D, La Rue B, King J, Montgomery AH, Carroll M, Baus J, Sinha S, Wendt FR, Song B, Chakraborty R, Budowle B, Sinha SK

Abstract
We report here a novel multiplexed DNA analysis system consisting of 20 Alu markers and Amelogenin for analysis of highly degraded forensic biological samples. The key to the success of the system in obtaining results from degraded samples is the primer design yielding small amplicon size (60-125bp) for all 20 markers. The markers included in the InnoTyper(®) 21 system are bi-allelic, having two possible allelic states (insertion or null) and thus termed INNULs. The markers are short interspersed nuclear elements (SINEs), a category of retrotransposable elements (REs) which are non-coding genomic DNA repeat sequences, or "mobile insertion elements," comprising approximately 40% of the human genome. Alu elements are primate specific SINEs that have reached a copy number in excess of one million in the human genome, which makes these markers highly sensitive and desirable for forensic samples with extremely degraded DNA. Until now however, due to the inherent size difference associated with insertion and no insertion alleles, the use of Alu REs has not been practical for forensic applications. The novel primer design described herein has allowed the development of a multiplexed Alu system yielding fragment sizes amenable to degraded DNA samples, as frequently encountered in missing persons cases or forensic samples such as hair shafts. Although use of Alus in human identity has been studied using single marker amplification and reported before, we report for the first time development and validation of a system with multiplexed RE markers. Studies performed include PCR optimization, species specificity, sensitivity, degradation and inhibition, precision and accuracy, nonprobative samples, mixture, and population database studies. A population study using 592 samples including five populations was performed using InnoTyper 21. The data indicated the random match probability for the combination of these 20 Alu markers was greater than 1 in 3.8 million for the populations studied, indicating the greater statistical power of these autosomal nuclear DNA markers over haplotype systems typically used in such degraded samples. Results demonstrate the system is successful in obtaining results from highly degraded DNA. A sensitivity study performed demonstrated at least 95% recovery of alleles from as low as 50pg of total input DNA, and partial profiles from as low as 25pg. This study has demonstrated that the bi-allelic INNULs in the InnoTyper 21 system provide a sensitivity of detection and a power of discrimination that makes them useful for human identification of extremely degraded samples.

PMID: 28391141 [PubMed - as supplied by publisher]

Methylene blue inhibits GABAA receptors by interaction with GABA binding site.

Mon, 04/10/2017 - 07:33
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Methylene blue inhibits GABAA receptors by interaction with GABA binding site.

Neuropharmacology. 2017 Apr 05;:

Authors: Chen Z, Liu R, Yang SH, Dillon GH, Huang R

Abstract
Methylene blue (MB) is commonly used in diagnostic procedures and is also used to treat various medical conditions. Neurological effects of MB have been reported in clinical observations and experimental studies. Thus the modulation of GABAA receptor function by MB was investigated. Whole-cell GABA-activated currents were recorded from HEK293 cells expressing various GABAA receptor subunit configurations. MB inhibition of GABA currents was apparent at 3 μM, and it had an IC50 of 31 μM in human α1β2γ2 receptors. The MB action was rapid and reversible. MB inhibition was not mediated via the picrotoxin site, as a mutation (T6'F of the β2 subunit) known to confer resistance to picrotoxin had no effect on MB-induced inhibition. Blockade of GABAA receptors by MB was demonstrated across a range of receptors expressing varying subunits, including those expressed at extrasynaptic sites. The sensitivity of α1β2 receptors to MB was similar to that observed in α1β2γ2 receptors, indicating that MB's action via the benzodiazepine or Zn(2+) site is unlikely. MB-induced inhibition of GABA response was competitive with respect to GABA. Furthermore, mutation of α1 F64 to A and β2 Y205 to F in the extracellular N-terminus, both residues which are known to comprise GABA binding pocket, remarkably diminished MB inhibition of GABA currents. These data suggest that MB inhibits GABAA receptor function by direct or allosteric interaction with the GABA binding site. Finally, in mouse hippocampal CA1 pyramidal neurons, MB inhibited GABA-activated currents as well as GABAergic IPSCs. We demonstrate that MB directly inhibits GABAA receptor function, which may underlie some of the effects of MB on the CNS.

PMID: 28390894 [PubMed - as supplied by publisher]

Edoxaban: Defining place in therapy for the newest direct acting oral anticoagulant.

Mon, 04/10/2017 - 07:33
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Edoxaban: Defining place in therapy for the newest direct acting oral anticoagulant.

Am J Med. 2017 Apr 05;:

Authors: Gibson CM, Finks SW

Abstract
Edoxaban is the most recently approved factor Xa inhibitor within the class of direct oral anticoagulants (DOACs). Like other DOACs, edoxaban was approved by the FDA for treatment of venous thromboembolism and prevention of stroke in patients with non-valvular atrial fibrillation. Similar to other DOACs, edoxaban has fewer drug-drug interactions than warfarin and does not require routine laboratory monitoring. Unlike other DOACs, edoxaban has yet to be approved for secondary or postoperative venous thromboembolism thromboprophylaxis. Currently, no antidote for edoxaban is available. To optimally prescribe agents in the DOAC class, it is critical that providers 1) understand how the agents compare and 2) identify specific settings where one agent may be preferred over another.

PMID: 28390791 [PubMed - as supplied by publisher]

Fluorescence properties of doxorubicin in PBS buffer and PVA films.

Sun, 04/09/2017 - 07:38

Fluorescence properties of doxorubicin in PBS buffer and PVA films.

J Photochem Photobiol B. 2017 Mar 30;170:65-69

Authors: Shah S, Chandra A, Kaur A, Sabnis N, Lacko A, Gryczynski Z, Fudala R, Gryczynski I

Abstract
We studied steady-state and time-resolved fluorescence properties of an anticancer drug Doxorubicin in a saline buffer and poly-vinyl alcohol (PVA) film. Absorption of Doxorubicin, located at blue-green spectral region, allows a convenient excitation with visible light emitting diodes or laser diodes. Emission of Doxorubicin with maximum near 600nm can be easily detected with photomultipliers and CCD cameras. Both, absorption and fluorescence spectra in polymeric matrix show more pronounced vibronic structures than in solution. Also, the steady-state anisotropy in the polymer film is significantly higher than in the saline solution. In PVA film the fluorescence anisotropy is about 0.30 whereas in the saline buffer only 0.07. Quantum efficiencies of Doxorubicin were compared to a known standard Rhodamine 101 which has fluorescence emission in a similar spectral region. The quantum yield of Doxorubicin in PVA film is more than 10% and about twice higher than in the saline solution. Similarly, the lifetime of doxorubicin in PVA film is about 2ns whereas in the saline solution only about 1ns. The fluorescence anisotropy decays show that Doxorubicin molecules are freely rotating in the saline buffer with a correlation time of about 290ps, and are almost completely immobilized in the PVA film. The spectroscopic investigations presented in this manuscript are important, as they provide answers to changes in molecular properties of Doxorubicin depending changes in the local environment, which is useful when synthesizing nanoparticles for Doxorubicin entrapment.

PMID: 28390260 [PubMed - as supplied by publisher]

Pyruvate preserves antiglycation defenses in porcine brain after cardiac arrest.

Sat, 04/01/2017 - 07:33

Pyruvate preserves antiglycation defenses in porcine brain after cardiac arrest.

Exp Biol Med (Maywood). 2017 Jan 01;:1535370217703353

Authors: Scott GF, Nguyen AQ, Cherry BH, Hollrah RA, Salinas I, Williams AG, Ryou MG, Mallet RT

Abstract
Cardiac arrest (CA) and cardiocerebral resuscitation (CCR)-induced ischemia-reperfusion imposes oxidative and carbonyl stress that injures the brain. The ischemic shift to anaerobic glycolysis, combined with oxyradical inactivation of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), provokes excessive formation of the powerful glycating agent, methylglyoxal. The glyoxalase (GLO) system, comprising the enzymes glyoxalase 1 (GLO1) and GLO2, utilizes reduced glutathione (GSH) supplied by glutathione reductase (GR) to detoxify methylglyoxal resulting in reduced protein glycation. Pyruvate, a natural antioxidant that augments GSH redox status, could sustain the GLO system in the face of ischemia-reperfusion. This study assessed the impact of CA-CCR on the cerebral GLO system and pyruvate's ability to preserve this neuroprotective system following CA. Domestic swine were subjected to 10 min CA, 4 min closed-chest CCR, defibrillation and 4 h recovery, or to a non-CA sham protocol. Sodium pyruvate or NaCl control was infused (0.1 mmol/kg/min, intravenous) throughout CCR and the first 60 min recovery. Protein glycation, GLO1 content, and activities of GLO1, GR, and GAPDH were analyzed in frontal cortex biopsied at 4 h recovery. CA-CCR produced marked protein glycation which was attenuated by pyruvate treatment. GLO1, GR, and GAPDH activities fell by 86, 55, and 30%, respectively, after CA-CCR with NaCl infusion. Pyruvate prevented inactivation of all three enzymes. CA-CCR sharply lowered GLO1 monomer content with commensurate formation of higher molecular weight immunoreactivity; pyruvate preserved GLO1 monomers. Thus, ischemia-reperfusion imposed by CA-CCR disabled the brain's antiglycation defenses. Pyruvate preserved these enzyme systems that protect the brain from glycation stress. Impact statement Recent studies have demonstrated a pivotal role of protein glycation in brain injury. Methylglyoxal, a by-product of glycolysis and a powerful glycating agent in brain, is detoxified by the glutathione-catalyzed glyoxalase (GLO) system, but the impact of cardiac arrest (CA) and cardiocerebral resuscitation (CCR) on the brain's antiglycation defenses is unknown. This study in a swine model of CA and CCR demonstrated for the first time that the intense cerebral ischemia-reperfusion imposed by CA-resuscitation disabled glyoxalase-1 and glutathione reductase (GR), the source of glutathione for methylglyoxal detoxification. Moreover, intravenous administration of pyruvate, a redox-active intermediary metabolite and antioxidant in brain, prevented inactivation of glyoxalase-1 and GR and blunted protein glycation in cerebral cortex. These findings in a large mammal are first evidence of GLO inactivation and the resultant cerebral protein glycation after CA-resuscitation, and identify novel actions of pyruvate to minimize protein glycation in postischemic brain.

PMID: 28361585 [PubMed - as supplied by publisher]

Tuberculin skin test and interferon-gamma release assay use among privately insured persons in the United States.

Thu, 03/30/2017 - 07:34
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Tuberculin skin test and interferon-gamma release assay use among privately insured persons in the United States.

Int J Tuberc Lung Dis. 2017 Mar 28;:

Authors: Owusu-Edusei K, Stockbridge EL, Winston CA, Kolasa M, Miramontes R

Abstract
<h2>OBJECTIVE:</h2><p>To describe tuberculin skin test (TST) and interferon-gamma release assay (IGRA) (i.e., QuantiFERON(&reg;)-TB &lsqb;QFT&rsqb; and T-SPOT(&reg;).<italic>TB</italic> &lsqb;T-SPOT&rsqb;) use among privately insured persons in the United States over a 15-year period.</p><h2>METHODS:</h2><p>We used current procedural terminology (CPT) codes for the TST and IGRAs to extract out-patient claims (2000&ndash;2014) and determined usage (claims/100&thinsp;000). The &chi;(2) test for trend in proportions was used to describe usage trends for select periods.</p><h2>RESULTS:</h2><p>The TST was the dominant (&gt;80&percnt;) test in each year. Publication of guidelines preceded the assignment of QFT and T-SPOT CPT codes by 1 year (2006 for QFT; 2011 for T-SPOT). QFT usage was higher (<italic>P</italic> &lt; 0.01) than T-SPOT in each year. The average annual increase in the use of QFT was higher than that of T-SPOT (35 vs. 3.8/100&thinsp;000), and more so when the analytic period was 2011&ndash;2014 (65 vs. 38/100&thinsp;000). However, during that 4-year period (2011&ndash;2014), TST use trended downward, with an average annual decrease of 28/100&thinsp;000. The annual proportion of enrollees tested ranged from 1.1&percnt; to 1.5&percnt;.</p><h2>CONCLUSIONS:</h2><p>These results suggest a gradual shift from the use of the TST to the newer IGRAs. Future studies can assess the extent, if any, to which the shift from the use of the TST to IGRAs evolved over time.</p&gt.

PMID: 28351463 [PubMed - as supplied by publisher]

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