Publications by authors named "J Härtner"

26 Publications

  • Page 1 of 1

Flexible High-Resolution Force and Dimpling Measurement System for Pia and Dura Penetration during In Vivo Microelectrode Insertion into Rat Brain.

IEEE Trans Biomed Eng 2021 Apr 2;PP. Epub 2021 Apr 2.

Objective: Understanding the in vivo force and tissue dimpling during micro-electrode implantation into the brain are important for neuro-electrophysiology to minimize damage while enabling accurate placement and stable chronic extracellular electrophysiological recordings. Prior studies were unable to measure the sub-mN forces exerted during in vivo insertion of small electrodes. Here, we have investigated the in vivo force and dimpling depth profiles during brain surface membrane rupture (including dura) in anesthetized rats.

Methods: A N-resolution cantilever beam-based measurement system was designed, built, and calibrated and adapted for in vivo use. A total of 244 in vivo insertion tests were conducted on 8 anesthetized rats with 121 through pia mater and 123 through dura and pia combined.

Results: Both microwire tip sharpening and diameter reduction reduced membrane rupture force (insertion force) and eased brain surface penetration. But dimpling depth and rupture force are not always strongly correlated. Multi-shank silicon probes showed smaller dimpling and rupture force per shank than single shank devices.

Conclusion: A force measurement system with flexible range and N-level resolution (up to 0.032 N) was achieved and proved feasible. For both pia-only and dura-pia penetrations in anesthetized rats, the rupture force and membrane dimpling depth at rupture are linearly related to the microwire diameter.

Significance: We have developed a new system with both N-level resolution and capacity to be used in vivo for measurement of force profiles of various neural interfaces into the brain. This allows quantification of brain tissue cutting and provides design guidelines for optimal neural interfaces.
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http://dx.doi.org/10.1109/TBME.2021.3070781DOI Listing
April 2021

Tactile acuity of fingertips and hand representation size in human Area 3b and Area 1 of the primary somatosensory cortex.

Neuroimage 2021 May 27;232:117912. Epub 2021 Feb 27.

Functional Imaging Unit, Center for Diagnostic Radiology, University Medicine of Greifswald, Walther-Rathenau-Str.46, D-17475 Greifswald, Germany. Electronic address:

Intracortical mapping in monkeys revealed a full body map in all four cytoarchitectonic subdivisions of the contralateral primary somatosensory cortex (S1), as well as positive associations between spatio-tactile acuity performance of the fingers and their representation field size especially within cytoarchitectonic Area 3b and Area 1. Previous non-invasive investigations on these associations in humans assumed a monotonous decrease of representation field size from index finger to little finger although the field sizes are known to change in response to training or in disease. Recent developments improved noninvasive functional mapping of S1 by a) adding a cognitive task during repetitive stimulation to decrease habituation to the stimuli, b) smaller voxel size of fMRI-sequences, c) surface-based analysis accounting for cortical curvature, and d) increase of spatial specificity for fMRI data analysis by avoidance of smoothing, partial volume effects, and pial vein signals. We here applied repetitive pneumatic stimulation of digit 1 (D1; thumb) and digit 5 (D5; little finger) on both hands to investigate finger/hand representation maps in the complete S1, but also in cytoarchitectonic Areas 1, 2, 3a, and 3b separately, in 21 healthy volunteers using 3T fMRI. The distances between activation maxima of D1 and D5 were evaluated by two independent raters, blinded for performance parameters. The fingertip representations showed a somatotopy and were localized in the transition region between the crown and the anterior wall of the post central gyrus agreeing with Area 1 and 3b. Participants were comprehensively tested for tactile performance using von Freyhair filaments to determine cutaneous sensory thresholds (CST) as well as grating orientation thresholds (GOT) and two-point resolution (TPD) for spatio-tactile acuity testing. Motor performance was evaluated with pinch grip performance (Roeder test). We found bilateral associations of D1-D5 distance for GOT thresholds and partially also for TPD in Area 3b and in Area 1, but not if using the complete S1 mask. In conclusion, we here demonstrate that 3T fMRI is capable to map associations between spatio-tactile acuity and the fingertip representation in Area 3b and Area 1 in healthy participants.
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http://dx.doi.org/10.1016/j.neuroimage.2021.117912DOI Listing
May 2021

Modifications in fMRI Representation of Mental Rotation Following a 6 Week Graded Motor Imagery Training in Chronic CRPS Patients.

J Pain 2021 Jan 6. Epub 2021 Jan 6.

Functional Imaging Unit, Institute of Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, Germany. Electronic address:

Complex regional pain syndrome (CRPS) is a neuropathic pain condition that is difficult to treat. For behavioral interventions, graded motor imagery (GMI) showed relevant effects, but underlying neural substrates in patient groups have not been investigated yet. A previous study investigating differences in the representation of a left/right hand judgment task demonstrated less recruitment of subcortical structures, such as the putamen, in CRPS patients than in healthy controls. In healthy volunteers, the putamen activity increased after a hand judgment task training. In order to test for longitudinal effects of GMI training, we investigated 20 CRPS patients in a wait-list crossover design with 3 evaluation time points. Patients underwent a 6 week GMI treatment and a 6 week waiting period in a randomized group assignment and treatment groups were evaluated by a blinded rater. When compared to healthy matched controls at baseline, CRPS patients showed less functional activation in areas processing visual input, left sensorimotor cortex, and right putamen. Only GMI treatment, but not the waiting period showed an effect on movement pain and hand judgment task performance. Regression analyses revealed positive associations of movement pain with left anterior insula activation at baseline. Right intraparietal sulcus activation change during GMI was associated with a gain in performance of the hand judgment task. The design used here is reliable for investigating the functional representation of the hand judgment task in an intervention study. PERSPECTIVE: Twenty chronic CRPS patients underwent a 6 week GMI intervention in a randomized wait-list crossover design. functional MRI was tested pre and post for the hand lateralization task which improved over GMI but not over WAITING. Performance gain was positively related to right parietal functional MRI activation.
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http://dx.doi.org/10.1016/j.jpain.2020.12.003DOI Listing
January 2021

Characterizing the human APOE epsilon 4 knock-in transgene in female and male rats with multimodal magnetic resonance imaging.

Brain Res 2020 11 31;1747:147030. Epub 2020 Jul 31.

Northeastern Univ, Center for Translational NeuroImaging, Boston, MA, United States; Northeastern Univ, Dept. Pharmaceutical Sciences, Boston, MA, United States. Electronic address:

The APOE Ɛ4 genotype is the most prevalent genetic risk for Alzheimer's disease (AD). Women carriers of Ɛ4 have higher risk for an early onset of AD than men. Human imaging studies suggest apolipoprotein Ɛ4 may affect brain structures associated with cognitive decline in AD many years before disease onset. It was hypothesized that female APOE Ɛ4 carriers would present with decreased cognitive function and neuroradiological evidence of early changes in brain structure and function as compared to male carriers. Six-month old wild-type (WT) and human APOE Ɛ4 knock-in (TGRA8960), male and female Sprague Dawley rats were studied for changes in brain structure using voxel-based morphometry, alteration in white and gray matter microarchitecture using diffusion weighted imaging with indices of anisotropy, and functional coupling using resting state BOLD functional connectivity. Images from each modality were registered to, and analyzed, using a 3D MRI rat atlas providing site-specific data on over 168 different brain areas. Quantitative volumetric analysis revealed areas involved in memory and arousal were significantly different between Ɛ4 and wild-type (WT) females, with few differences between male genotypes. Diffusion weighted imaging showed few differences between WT and Ɛ4 females, while male genotypes showed significant different measures in fractional anisotropy and apparent diffusion coefficient. Resting state functional connectivity showed Ɛ4 females had greater connectivity between areas involved in cognition, emotion, and arousal compared to WT females, with male Ɛ4 showing few differences from controls. Interestingly, male Ɛ4 showed increased anxiety and decreased performance in spatial and episodic memory tasks compared to WT males, with female genotypes showing little difference across behavioral tests. The sex differences in behavior and diffusion weighted imaging suggest male carriers of the Ɛ4 allele may be more vulnerable to cognitive and emotional complications compared to female carriers early in life. Conversely, the data may also suggest that female carriers are more resilient to cognitive/emotional problems at this stage of life perhaps due to altered brain volumes and enhanced connectivity.
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http://dx.doi.org/10.1016/j.brainres.2020.147030DOI Listing
November 2020

ADAR1-Dependent RNA Editing Promotes MET and iPSC Reprogramming by Alleviating ER Stress.

Cell Stem Cell 2020 08 11;27(2):300-314.e11. Epub 2020 May 11.

Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), Universidade de Santiago de Compostela (USC)-Health Research Institute (IDIS), Santiago de Compostela 15782, Spain; Department of Physiology, USC, Santiago de Compostela 15782, Spain. Electronic address:

RNA editing of adenosine to inosine (A to I) is catalyzed by ADAR1 and dramatically alters the cellular transcriptome, although its functional roles in somatic cell reprogramming are largely unexplored. Here, we show that loss of ADAR1-mediated A-to-I editing disrupts mesenchymal-to-epithelial transition (MET) during induced pluripotent stem cell (iPSC) reprogramming and impedes acquisition of induced pluripotency. Using chemical and genetic approaches, we show that absence of ADAR1-dependent RNA editing induces aberrant innate immune responses through the double-stranded RNA (dsRNA) sensor MDA5, unleashing endoplasmic reticulum (ER) stress and hindering epithelial fate acquisition. We found that A-to-I editing impedes MDA5 sensing and sequestration of dsRNAs encoding membrane proteins, which promote ER homeostasis by activating the PERK-dependent unfolded protein response pathway to consequently facilitate MET. This study therefore establishes a critical role for ADAR1 and its A-to-I editing activity during cell fate transitions and delineates a key regulatory layer underlying MET to control efficient reprogramming.
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http://dx.doi.org/10.1016/j.stem.2020.04.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7415614PMC
August 2020

A Retrospective Cohort Study to Assess the Impact of an Inpatient Infectious Disease Telemedicine Consultation Service on Hospital and Patient Outcomes.

Clin Infect Dis 2020 02;70(5):763-770

Network Office of Research and Innovation, Lehigh Valley Health Network, Allentown, Pennsylvania.

Background: Here, we review our experience of providing inpatient infectious disease (ID) consultations using real-time interactive telemedicine assessments. We sought to obtain a baseline and document trends regarding the use of telemedicine ID (teleID) consults as an adjunct to the standard of care through the time period in which teleID consultations were introduced.

Methods: Data were pulled via manual, retrospective chart reviews of the electronic medical record. Primary outcomes included lengths of stay (LOS), antibiotic usage, and relapse incidences.

Results: There were a total of 244 patients at 1 remote hospital site who were provided with ID consultations, either in person, via teleID, or both. Before the availability of teleID (pre-teleID), there were 73 patients transferred for ID consults, while 171 patients were seen via teleID once available. While all 73 patients in the pre-teleID group were transferred from the remote hospital to the hub hospital, only 14 (8.2%) of all remote hospital patients assessed by teleID were transferred. Patient LOS across both facilities decreased when patients were seen via teleID, compared to pre-teleID (P = .0001). The median number of days that patients received antibiotics decreased in the teleID group (median 15, interquartile range [IQR] 9-25), compared to the pre-teleID group (median 19, IQR 11-28), but this decrease was not statistically significant (P = .0770). There was no statistically significant difference in relapse rates, although data were lacking because of patients being lost to follow-up.

Conclusions: ID telemedicine practice directed at inpatients appears to be a promising route of care.
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http://dx.doi.org/10.1093/cid/ciz293DOI Listing
February 2020

In search of early neuroradiological biomarkers for Parkinson's Disease: Alterations in resting state functional connectivity and gray matter microarchitecture in PINK1 -/- rats.

Brain Res 2019 03 31;1706:58-67. Epub 2018 Oct 31.

Center for Translational NeuroImaging, Northeastern Univ, Boston, MA, United States. Electronic address:

Parkinson's Disease (PD) is the second most common neurodegenerative disorder, with 60,000 new cases diagnosed each year in the US. There are multiple animal models of PD that attempt to mimic the effects of the disease through genetic alteration. Combined with advanced imaging techniques, these animal models are critical in tracking the neurobiological and behavioral aspects of disease progression and identifying early biomarkers of PD. PTEN-induced putative kinase 1 (PINK1) is a mitochondrial protein kinase involved in protecting neurons from stress-induced mitochondrial dysfunction. A mutation in the PINK1 gene that alters its function can increase the risk for autosomal recessive familial PD and similarly, through genetic deletion of portions of the PINK1 gene in animal models (i.e., "PINK1 knock-out (-/-) rats) produces a progressive loss of dopaminergic neurons in the substantia nigra which is analogous to the pathological hallmarks in human PD patients. In this exploratory study, we used volumetric analysis, resting-state functional connectivity MRI (rs-fcMRI) and diffusion-weighted imaging (DWI) to identify neurobiological differences between wild-type (WT) and PINK1 (-/-) rats. All voxel-based measures for each modality were registered to a rat MRI atlas with 171 segmented and annotated brain regions allowing for the measurement of subtle changes in brain function and architecture that go well beyond typical clinical MRI scanning protocols. Basal ganglia, the mesencephalic dopamine system, the limbic cortex, and the hippocampal complex showed changes in putative gray matter microarchitecture, reflected by shifts in quantitative anisotropy. Rs-fcMRI revealed altered resting state connectivity in many brain areas including the basal ganglia, amygdala, cortex, septum, pons etc. Taken together, these results inform us on a wide range of whole-brain changes occurring in a PD rat model in the absence of cognitive and motor deficits, serving as potential biomarkers and targets for treatment.
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http://dx.doi.org/10.1016/j.brainres.2018.10.033DOI Listing
March 2019

Evidence of Neurobiological Changes in the Presymptomatic PINK1 Knockout Rat.

J Parkinsons Dis 2018 ;8(2):281-301

NOVA Southeastern University, Ft. Lauderdale, FL, USA.

Background: Genetic models of Parkinson's disease (PD) coupled with advanced imaging techniques can elucidate neurobiological disease progression, and can help identify early biomarkers before clinical signs emerge. PTEN-induced putative kinase 1 (PINK1) helps protect neurons from mitochondrial dysfunction, and a mutation in the associated gene is a risk factor for recessive familial PD. The PINK1 knockout (KO) rat is a novel model for familial PD that has not been neuroradiologically characterized for alterations in brain structure/function, alongside behavior, prior to 4 months of age.

Objective: To identify biomarkers of presymptomatic PD in the PINK1 -/- rat at 3 months using magnetic resonance imaging techniques.

Methods: At postnatal weeks 12-13; one month earlier than previously reported signs of motor and cognitive dysfunction, this study combined imaging modalities, including assessment of quantitative anisotropy across 171 individual brain areas using an annotated MRI rat brain atlas to identify sites of gray matter alteration between wild-type and PINK1 -/- rats.

Results: The olfactory system, hypothalamus, thalamus, nucleus accumbens, and cerebellum showed differences in anisotropy between experimental groups. Molecular analyses revealed reduced levels of glutathione, ATP, and elevated oxidative stress in the substantia nigra, striatum and deep cerebellar nuclei. Mitochondrial genes encoding proteins in Complex IV, along with mRNA levels associated with mitochondrial function and genes involved in glutathione synthesis were reduced. Differences in brain structure did not align with any cognitive or motor impairment.

Conclusions: These data reveal early markers, and highlight novel brain regions involved in the pathology of PD in the PINK1 -/- rat before behavioral dysfunction occurs.
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http://dx.doi.org/10.3233/JPD-171273DOI Listing
October 2019

Interaction of Norepinephrine and Glucocorticoids Modulate Inhibition of Principle Cells of Layer II Medial Entorhinal Cortex in Male Mice.

Front Synaptic Neurosci 2018 28;10. Epub 2018 Mar 28.

Neuroscience Program, Tulane Brain Institute, Tulane University, New Orleans, LA, United States.

Spatial memory processing requires functional interaction between the hippocampus and the medial entorhinal cortex (MEC). The grid cells of the MEC are most abundant in layer II and rely on a complex network of local inhibitory interneurons to generate spatial firing properties. Stress can cause spatial memory deficits in males, but the specific underlying mechanisms affecting the known memory pathways remain unclear. Stress activates both the autonomic nervous system and the hypothalamic-pituitary-adrenal axis to release norepinephrine (NE) and glucocorticoids, respectively. Given that adrenergic receptor (AR) and glucocorticoid receptor (GR) expression is abundant in the MEC, both glucocorticoids and NE released in response to stress may have rapid effects on MEC-LII networks. We used whole-cell patch clamp electrophysiology in MEC slice preparations from male mice to test the effects of NE and glucocorticoids on inhibitory synaptic inputs of MEC-LII principal cells. Application of NE (100 μM) increased the frequency and amplitude of spontaneous inhibitory post-synaptic currents (sIPSCs) in approximately 75% of the principal cells tested. Unlike NE, bath application of dexamethasone (Dex, 1 μM), a synthetic glucocorticoid, or corticosterone (1 μM) the glucocorticoid in rodents, rapidly decreased the frequency of sIPSCs, but not miniature (mIPSCs) in MEC-LII principal cells. Interestingly, pre-treatment with Dex prior to NE application led to an NE-induced increase in sIPSC frequency in all cells tested. This effect was mediated by the α1-AR, as application of an α1-AR agonist, phenylephrine (PHE) yielded the same results, suggesting that a subset of cells in MEC-LII are unresponsive to α1-AR activation without prior activation of GR. We conclude that activation of GRs primes a subset of principal cells that were previously insensitive to NE to become responsive to α1-AR activation in a transcription-independent manner. These findings demonstrate the ability of stress hormones to markedly alter inhibitory signaling within MEC-LII circuits and suggest the intriguing possibility of modulation of network processing upstream of the hippocampus.
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http://dx.doi.org/10.3389/fnsyn.2018.00003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883071PMC
March 2018

RNA-editing enzymes ADAR1 and ADAR2 coordinately regulate the editing and expression of Ctn RNA.

FEBS Lett 2017 09 30;591(18):2890-2904. Epub 2017 Aug 30.

Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, IL, USA.

Adenosine deaminases acting on RNA (ADARs) are proteins that catalyse widespread A-to-I editing within RNA sequences. We recently reported that ADAR2 edits and stabilizes nuclear-retained Cat2 transcribed nuclear RNA (Ctn RNA). Here, we report that ADAR1 coordinates with ADAR2 to regulate editing and stability of Ctn RNA. We observe an RNA-dependent interaction between ADAR1 and ADAR2. Furthermore, ADAR1 negatively regulates interaction of Ctn RNA with RNA-destabilizing proteins. We also show that breast cancer (BC) cells display elevated ADAR1 but not ADAR2 levels, compared to nontumourigenic cells. Additionally, BC patients with elevated levels of ADAR1 show low survival. Our findings provide insights into overlapping substrate preferences of ADARs and potential involvement of ADAR1 in BC.
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http://dx.doi.org/10.1002/1873-3468.12795DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5612911PMC
September 2017

Adenosine-to-inosine RNA editing by ADAR1 is essential for normal murine erythropoiesis.

Exp Hematol 2016 10 1;44(10):947-63. Epub 2016 Jul 1.

St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia; Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia. Electronic address:

Adenosine deaminases that act on RNA (ADARs) convert adenosine residues to inosine in double-stranded RNA. In vivo, ADAR1 is essential for the maintenance of hematopoietic stem/progenitors. Whether other hematopoietic cell types also require ADAR1 has not been assessed. Using erythroid- and myeloid-restricted deletion of Adar1, we demonstrate that ADAR1 is dispensable for myelopoiesis but is essential for normal erythropoiesis. Adar1-deficient erythroid cells display a profound activation of innate immune signaling and high levels of cell death. No changes in microRNA levels were found in ADAR1-deficient erythroid cells. Using an editing-deficient allele, we demonstrate that RNA editing is the essential function of ADAR1 during erythropoiesis. Mapping of adenosine-to-inosine editing in purified erythroid cells identified clusters of hyperedited adenosines located in long 3'-untranslated regions of erythroid-specific transcripts and these are ADAR1-specific editing events. ADAR1-mediated RNA editing is essential for normal erythropoiesis.
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http://dx.doi.org/10.1016/j.exphem.2016.06.250DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5035604PMC
October 2016

RNA editing by ADAR1 prevents MDA5 sensing of endogenous dsRNA as nonself.

Science 2015 Sep 23;349(6252):1115-20. Epub 2015 Jul 23.

St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia. Department of Medicine, St. Vincent's Hospital, University of Melbourne, Fitzroy, Victoria 3065, Australia.

Adenosine-to-inosine (A-to-I) editing is a highly prevalent posttranscriptional modification of RNA, mediated by ADAR (adenosine deaminase acting on RNA) enzymes. In addition to RNA editing, additional functions have been proposed for ADAR1. To determine the specific role of RNA editing by ADAR1, we generated mice with an editing-deficient knock-in mutation (Adar1(E861A), where E861A denotes Glu(861)→Ala(861)). Adar1(E861A/E861A) embryos died at ~E13.5 (embryonic day 13.5), with activated interferon and double-stranded RNA (dsRNA)-sensing pathways. Genome-wide analysis of the in vivo substrates of ADAR1 identified clustered hyperediting within long dsRNA stem loops within 3' untranslated regions of endogenous transcripts. Finally, embryonic death and phenotypes of Adar1(E861A/E861A) were rescued by concurrent deletion of the cytosolic sensor of dsRNA, MDA5. A-to-I editing of endogenous dsRNA is the essential function of ADAR1, preventing the activation of the cytosolic dsRNA response by endogenous transcripts.
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http://dx.doi.org/10.1126/science.aac7049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5444807PMC
September 2015

MicroRNA-21 integrates pathogenic signaling to control pulmonary hypertension: results of a network bioinformatics approach.

Circulation 2012 Mar 27;125(12):1520-32. Epub 2012 Feb 27.

Brigham and Women's Hospital, New Research Building, 77 Ave. Louis Pasteur, Boston, MA 02115, USA.

Background: Pulmonary hypertension (PH) is driven by diverse pathogenic etiologies. Owing to their pleiotropic actions, microRNA molecules are potential candidates for coordinated regulation of these disease stimuli.

Methods And Results: Using a network biology approach, we identify microRNA associated with multiple pathogenic pathways central to PH. Specifically, microRNA-21 (miR-21) is predicted as a PH-modifying microRNA, regulating targets integral to bone morphogenetic protein (BMP) and Rho/Rho-kinase signaling as well as functional pathways associated with hypoxia, inflammation, and genetic haploinsufficiency of BMP receptor type 2. To validate these predictions, we have found that hypoxia and BMP receptor type 2 signaling independently upregulate miR-21 in cultured pulmonary arterial endothelial cells. In a reciprocal feedback loop, miR-21 downregulates BMP receptor type 2 expression. Furthermore, miR-21 directly represses RhoB expression and Rho-kinase activity, inducing molecular changes consistent with decreased angiogenesis and vasodilation. In vivo, miR-21 is upregulated in pulmonary tissue from several rodent models of PH and in humans with PH. On induction of disease in miR-21-null mice, RhoB expression and Rho-kinase activity are increased, accompanied by exaggerated manifestations of PH.

Conclusions: A network-based bioinformatic approach coupled with confirmatory in vivo data delineates a central regulatory role for miR-21 in PH. Furthermore, this study highlights the unique utility of network biology for identifying disease-modifying microRNA in PH.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.111.060269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3353408PMC
March 2012

MicroRNA-21 promotes fibrosis of the kidney by silencing metabolic pathways.

Sci Transl Med 2012 Feb;4(121):121ra18

Regulus Therapeutics, San Diego, CA 92121, USA.

Scarring of the kidney is a major public health concern, directly promoting loss of kidney function. To understand the role of microRNA (miRNA) in the progression of kidney scarring in response to injury, we investigated changes in miRNA expression in two kidney fibrosis models and identified 24 commonly up-regulated miRNAs. Among them, miR-21 was highly elevated in both animal models and in human transplanted kidneys with nephropathy. Deletion of miR-21 in mice resulted in no overt abnormality. However, miR-21(-/-) mice suffered far less interstitial fibrosis in response to kidney injury, a phenotype duplicated in wild-type mice treated with anti-miR-21 oligonucleotides. Global derepression of miR-21 target mRNAs was readily detectable in miR-21(-/-) kidneys after injury. Analysis of gene expression profiles up-regulated in the absence of miR-21 identified groups of genes involved in metabolic pathways, including the lipid metabolism pathway regulated by peroxisome proliferator-activated receptor-α (Pparα), a direct miR-21 target. Overexpression of Pparα prevented ureteral obstruction-induced injury and fibrosis. Pparα deficiency abrogated the antifibrotic effect of anti-miR-21 oligonucleotides. miR-21 also regulated the redox metabolic pathway. The mitochondrial inhibitor of reactive oxygen species generation Mpv17l was repressed by miR-21, correlating closely with enhanced oxidative kidney damage. These studies demonstrate that miR-21 contributes to fibrogenesis and epithelial injury in the kidney in two mouse models and is a candidate target for antifibrotic therapies.
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http://dx.doi.org/10.1126/scitranslmed.3003205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3672221PMC
February 2012

MicroRNA-21 limits in vivo immune response-mediated activation of the IL-12/IFN-gamma pathway, Th1 polarization, and the severity of delayed-type hypersensitivity.

J Immunol 2011 Sep 17;187(6):3362-73. Epub 2011 Aug 17.

Division of Allergy and Immunology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.

An altered balance between Th1 and Th2 cytokines is responsible for a variety of immunoinflammatory disorders such as asthma, yet the role of posttranscriptional mechanisms, such as those mediated by microRNAs (miRs), in adjusting the relative magnitude and balance of Th cytokine expression have been largely unexplored. In this study, we show that miR-21 has a central role in setting a balance between Th1 and Th2 responses to Ags. Targeted ablation of miR-21 in mice led to reduced lung eosinophilia after allergen challenge, with a broadly reprogrammed immunoactivation transcriptome and significantly increased levels of the Th1 cytokine IFN-γ. Biological network-based transcriptome analysis of OVA-challenged miR-21(-/-) mice identified an unexpected prominent dysregulation of IL-12/IFN-γ pathways as the most significantly affected in the lungs, with a key role for miR-21 in IFN-γ signaling and T cell polarization, consistent with a functional miR-21 binding site in IL-12p35. In support of these hypotheses, miR-21 deficiency led dendritic cells to produce more IL-12 after LPS stimulation and OVA-challenged CD4(+) T lymphocytes to produce increased IFN-γ and decreased IL-4. Further, loss of miR-21 significantly enhanced the Th1-associated delayed-type hypersensitivity cutaneous responses. Thus, our results define miR-21 as a major regulator of Th1 versus Th2 responses, defining a new mechanism for regulating polarized immunoinflammatory responses.
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http://dx.doi.org/10.4049/jimmunol.1101235DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3175642PMC
September 2011

Role of ADARs in mouse development.

Curr Top Microbiol Immunol 2012 ;353:197-220

St. Vincent's Institute of Medical Research and Department of Medicine, St. Vincent's Hospital, University of Melbourne, Melbourne, VIC 3065, Australia.

RNA editing by deamination of adenosine to inosine (A-to-I editing) is a physiologically important posttranscriptional mechanism that can regulate expression of genes by modifying their transcripts. A-to-I editing is mediated by adenosine deaminases acting on RNA (ADAR) that can catalytically exchange adenosines to inosines, with varying efficiency, depending on the structure of the RNA substrates. Significant progress in understanding the biological function of mammalian ADARs has been made in the past decade by the creation and analysis of gene-targeted mice with disrupted or modified ADAR alleles. These studies have revealed important roles of ADARs in neuronal and hematopoietic tissue during embryonic and postnatal stages of mouse development.
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http://dx.doi.org/10.1007/82_2011_150DOI Listing
February 2012

ADAR1 is essential for the maintenance of hematopoiesis and suppression of interferon signaling.

Nat Immunol 2009 Jan 7;10(1):109-15. Epub 2008 Dec 7.

Department of Pediatric Oncology, Dana-Farber Cancer Institute; Harvard Medical School, Boston, Massachusetts 02115, USA.

The deaminase ADAR1 edits adenosines in nuclear transcripts of nervous tissue and is required in the fetal liver of the developing mouse embryo. Here we show by inducible gene disruption in mice that ADAR1 is essential for maintenance of both fetal and adult hematopoietic stem cells. Loss of ADAR1 in hematopoietic stem cells led to global upregulation of type I and II interferon-inducible transcripts and rapid apoptosis. Our findings identify ADAR1 as an essential regulator of hematopoietic stem cell maintenance and suppressor of interferon signaling that may protect organisms from the deleterious effects of interferon activation associated with many pathological processes, including chronic inflammation, autoimmune disorders and cancer.
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http://dx.doi.org/10.1038/ni.1680DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2701568PMC
January 2009

Specificity of ADAR-mediated RNA editing in newly identified targets.

RNA 2008 Jun 22;14(6):1110-8. Epub 2008 Apr 22.

Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.

Adenosine deaminases that act on RNA (ADARs) convert adenosines to inosine in both coding and noncoding double-stranded RNA. Deficiency in either ADAR1 or ADAR2 in mice is incompatible with normal life and development. While the ADAR2 knockout phenotype can be attributed to the lack of editing of the GluR-B receptor, the embryonic lethal phenotype caused by ADAR1 deficiency still awaits clarification. Recently, massive editing was observed in noncoding regions of mRNAs in mice and humans. Moreover, editing was observed in protein-coding regions of four mRNAs encoding FlnA, CyFip2, Blcap, and IGFBP7. Here, we investigate which of the two active mammalian ADAR enzymes is responsible for editing of these RNAs and whether any of them could possibly contribute to the phenotype observed in ADAR knockout mice. Editing of Blcap, FlnA, and some sites within B1 and B2 SINEs clearly depends on ADAR1, while other sites depend on ADAR2. Based on our data, substrate specificities can be further defined for ADAR1 and ADAR2. Future studies on the biological implications associated with a changed editing status of the studied ADAR targets will tell whether one of them turns out to be directly or indirectly responsible for the severe phenotype caused by ADAR1 deficiency.
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http://dx.doi.org/10.1261/rna.923308DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2390793PMC
June 2008

Liver disintegration in the mouse embryo caused by deficiency in the RNA-editing enzyme ADAR1.

J Biol Chem 2004 Feb 12;279(6):4894-902. Epub 2003 Nov 12.

Department of Molecular Neurobiology, Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany.

ADAR1 (adenosine deaminase acting on RNA-1) is widely expressed in mammals, but its biological role is unknown. We show here by gene targeting that ADAR1 selectively edits in vivo two of five closely spaced adenosines in the serotonin 5-hydroxytryptamine subtype 2C receptor pre-mRNA of nervous tissue; and hence, site-selective adenosine-to-inosine editing is indeed a function of ADAR1. Remarkably, homozygosity for two different null alleles of ADAR1 caused a consistent embryonic phenotype appearing early at embryonic day 11 and leading to death between embryonic days 11.5 and 12.5. This phenotype manifests a rapidly disintegrating liver structure, along with severe defects in definitive hematopoiesis, encompassing both erythroid and myeloid/granuloid progenitors as well as spleen colony-forming activity from the aorta-gonad-mesonephros region and fetal liver. Probably as a consequence of these developmental impairments, ADAR1-deficient embryonic stem cells failed to contribute to liver, bone marrow, spleen, thymus, and blood in adult chimeric mice. Thus, ADAR1 subserves critical steps in developing non-nervous tissue, which are likely to include transcript editing.
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http://dx.doi.org/10.1074/jbc.M311347200DOI Listing
February 2004

Regulation of ion channel/neurotransmitter receptor function by RNA editing.

Curr Opin Neurobiol 2003 Jun;13(3):279-83

Department of Molecular Neurobiology, Max-Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany.

RNA editing by select adenosine deamination (A-to-I editing) alters functional determinants in certain ion channels and neurotransmitter receptors in vertebrates and invertebrates. In most cases, edited and unedited versions of a given receptor/channel co-exist to expand the functional space of the receptor population. Recent studies have characterized K(+) channels in squid that are edited at multiple positions, revealed a role for Q/R site editing in AMPA receptor assembly, and demonstrated a link between serotonin levels and the extent of editing of a mammalian serotonin receptor.
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http://dx.doi.org/10.1016/s0959-4388(03)00062-xDOI Listing
June 2003

Point mutation in an AMPA receptor gene rescues lethality in mice deficient in the RNA-editing enzyme ADAR2.

Nature 2000 Jul;406(6791):78-81

Department of Molecular Neurobiology, Max-Planck Institute for Medical Research, Heidelberg, Germany.

RNA editing by site-selective deamination of adenosine to inosine alters codons and splicing in nuclear transcripts, and therefore protein function. ADAR2 (refs 7, 8) is a candidate mammalian editing enzyme that is widely expressed in brain and other tissues, but its RNA substrates are unknown. Here we have studied ADAR2-mediated RNA editing by generating mice that are homozygous for a targeted functional null allele. Editing in ADAR2-/- mice was substantially reduced at most of 25 positions in diverse transcripts; the mutant mice became prone to seizures and died young. The impaired phenotype appeared to result entirely from a single underedited position, as it reverted to normal when both alleles for the underedited transcript were substituted with alleles encoding the edited version exonically. The critical position specifies an ion channel determinant, the Q/R site, in AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate) receptor GluR-B pre-messenger RNA. We conclude that this transcript is the physiologically most important substrate of ADAR2.
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http://dx.doi.org/10.1038/35017558DOI Listing
July 2000

The effects of prenatal care utilization and maternal risk factors on pregnancy outcome between Mexican Americans and non-Hispanic whites.

J Natl Med Assoc 1993 Mar;85(3):195-202

Department of Family Resources and Human Development, Arizona State University, Tempe 85287-2502.

This study evaluates the effects of prenatal care classification and levels of maternal risk status on pregnancy outcomes in Mexican Americans and non-Hispanic whites in Arizona. All live birth certificates from 1986 and 1987 were reviewed yielding a total population of 101,206 (26,827 Mexican Americans). The adequacy of prenatal care was evaluated based on an index that includes six prenatal care groups. Two levels of maternal risk status (low and high) were defined based on a series of maternal risk factors. Overall, Mexican Americans had a greater proportion of maternal risk factors and a greater proportion of mothers with inadequate or no prenatal care compared with non-Hispanic whites. Prematurity and macrosomia were more prevalent than low birthweight in Mexican Americans. Low-risk status and adequate prenatal care regardless of ethnicity were found to be associated with a lower prevalence of low birthweight and preterm delivery. Whites, however, had a greater variation in the prevalence of low birthweight associated with changes in prenatal care utilization and maternal risk status compared with Mexican Americans. Finally, logistic regression analysis showed an independent effect of prenatal care, maternal risk status, maternal age, and maternal birthplace in predicting the overall low birthweight rate in Mexican Americans. The implications of these results are discussed relative to the usefulness of prenatal care as a health-care intervention in Mexican Americans.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2571882PMC
March 1993

Mexican-Americans' use of prenatal care and its relationship to maternal risk factors and pregnancy outcome.

Am J Prev Med 1992 Jan-Feb;8(1):1-7

Department of Family Resources and Human Development, Arizona State University, Tempe 85287-2502.

We evaluate the adequacy of prenatal care use and the association of use to a series of maternal risk factors and pregnancy outcomes, such as low birthweight, preterm delivery, and macrosomia in both Mexican-Americans and non-Hispanic whites in Arizona. The data came from all live-birth certificates from 1986 and 1987 for a total of 101,202 (26,826 Mexican-Americans). We evaluated the adequacy of prenatal care using a redesigned index that accounts for three factors: the month when prenatal care began, the number of prenatal care visits, and the duration of pregnancy. From this index we identified six prenatal care groups: intensive, adequate, intermediate, inadequate, no-care, and missing/unknown. Overall, we observed ethnic differences in patterns of prenatal care use, social profiles, and medical risk factors. Non-Hispanic whites, compared to Mexican-Americans, showed a greater risk for low birthweight and preterm delivery in those groups receiving poor prenatal care versus those who received adequate care. Within Mexican-Americans the risk of low birthweight was not the same for all subgroups. A higher overall prevalence of preterm delivery and macrosomia in comparison to low birthweight occurred in Mexican-Americans. We discuss the implications of the results for the identification, interpretation, evaluation, and public health significance of perinatal health problems of Mexican-Americans.
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June 1992

Breast-feeding policies and routines among Arizona hospitals and nursery staff: results and implications of a descriptive study.

J Am Diet Assoc 1991 Aug;91(8):923-5

Maricopa Department of Health Services, Division of Public Health, Phoenix, AZ 85006.

In 1988, Arizona's 61 hospitals providing obstetrical services were canvased with regard to hospital routines that favor either breast-feeding or bottle-feeding. Forty-five hospitals provided responses that were used in the survey. Practices favoring breast-feeding, which were reported by a majority of the hospitals (more than 50%), were demand feeding, staff assessment for "latch-on" (the action of nipple presentation and sucking initiation) and positioning, "rooming-in" (the practice of minimal mother-infant separation), and information about follow-up support services. Hospital practices suggested to promote bottle-feeding were the provision of pacifiers and supplemental water or glucose, issuance of formula packs at discharge, and a first feed of sterile water. A positive significant relationship was identified for policies advocating breast-feeding and the prevalence of breast-feeding encouragement from professional staff. Of 44 respondents, 41 indicated that their hospital's policies endorse breast-feeding as the ideal method of feeding healthy newborns. Hospital staff perceived that they encourage mothers to breast-feed and offer support to those who initiate breast-feeding. On the basis of this information, we conclude that dietetics practitioners should evaluate current breast-feeding practices and integrate policies supportive of breast-feeding into the health care system.
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August 1991

Lower-extremity amputations in NIDDM. 12-yr follow-up study in Pima Indians.

Diabetes Care 1988 Jan;11(1):8-16

Diabetes and Arthritis Epidemiology Section, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, Arizona.

The incidence of lower-extremity amputations was estimated in the Pima Indians of the Gila River Indian Community in Arizona, a population with a high prevalence of non-insulin-dependent diabetes mellitus (NIDDM). Between 1972 and 1984, from a study population of 4399 subjects, lower-extremity amputations were performed on 84 patients, 80 (95%) of whom had NIDDM. Among diabetic subjects, the incidence rate of first lower-extremity amputations was higher in men than in women. Rates increased significantly with increasing duration of diabetes. Presence of medial arterial calcification, retinopathy, or nephropathy; absence of patellar tendon reflexes; impaired great toe vibration-perception threshold; and degree of fasting and 2-h postload hyperglycemia were significant risk factors for amputations. Serum cholesterol concentration, blood pressure, age, and absence of Achilles tendon reflexes were not predictive of amputations. The death rate was greater in diabetic amputees than in diabetic nonamputees of similar age, sex, and duration of diabetes, and a significant increase in cardiovascular deaths was observed in diabetic subjects with amputations. The incidence rate of lower-extremity amputations in diabetic Pima Indians is higher than that reported in other diabetic populations. This may reflect differences in risk or a more complete case ascertainment than was possible in previous studies. If the latter is true, the rate of amputations in diabetic individuals may be higher than has been previously appreciated.
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http://dx.doi.org/10.2337/diacare.11.1.8DOI Listing
January 1988

Stability of carmustine in the presence of sodium bicarbonate.

Am J Hosp Pharm 1980 May;37(5):677-8

The stability of carmustine in 5% dextrose injection and 0.9% sodium chloride injection, with and without added sodium bicarbonate, was studied at room temperature. Solutions of carmustine (0.1 mg/ml) in dextrose or saline with and without added sodium bicarbonate (1 meq/ml) were prepared. After 0, 15, 30, 60, and 90 minutes, aliquots of each test solution were analyzed for carmustine using the Bratton-Marshall test with absorbance at 540 nm. There was no significant decomposition of carmustine in dextrose or saline alone. However, the addition of sodium bicarbonate increased carmustine degradation; after 90 minutes, approximately 73% of the active drug remained. It is recommended that carmustine be neither admixed with nor administered piggyback with parenteral infusion solutions containing sodium bicarbonate.
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May 1980