Publications by authors named "Alison L Young"

13 Publications

  • Page 1 of 1

Bbc3 loss enhances survival and protein clearance in neurons exposed to the organophosphate pesticide chlorpyrifos.

Toxicol Sci 2021 Jul 21. Epub 2021 Jul 21.

Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH.

Exposure to environmental toxicants can increase the risk of developing age-related neurodegenerative disorders. Exposure to the widely used organophosphate pesticide chlorpyrifos (CPF) is associated with increased risk of developing Alzheimer's disease (AD) and Parkinson's disease (PD), but the cellular mechanisms underlying CPF toxicity in neurons are not completely understood. We evaluated CPF toxicity in mouse primary cortical neuronal cultures, using RNA-Seq to identify cellular pathways modulated by CPF. CPF exposure altered the expression of genes associated with intrinsic apoptosis, significantly elevating expression of the pro-apoptotic mediator Bbc3/Puma. Bbc3 loss attenuated CPF driven neurotoxicity, induction of other intrinsic apoptosis regulatory genes including Trp53 and Pmaip1 (encoding the NOXA protein), and cleavage of apoptosis executors caspase 3 and PARP. CPF exposure was associated with enhanced expression of ER stress-related genes and proteins and the accumulation of high molecular weight protein species in primary neuronal cultures. No evidence of alterations in the ubiquitin-proteosome system were observed, however, autophagy-related proteins were upregulated in CPF-treated Bbc3-/- neuronal cultures compared with identically exposed WT cultures. Elevated autophagy-related protein expression in Bbc3-/- neuronal cultures was associated with a reduction in CPF-induced high molecular weight alpha-synuclein and tau immunoreactive protein aggregates. Studies indicate that Bbc3-/- neuronal cultures enhance the ER stress response and upregulate protein clearance mechanisms as a component of resistance to CPF-mediated toxicity.
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http://dx.doi.org/10.1093/toxsci/kfab090DOI Listing
July 2021

Plasma-borne indicators of inflammasome activity in Parkinson's disease patients.

NPJ Parkinsons Dis 2021 Jan 4;7(1). Epub 2021 Jan 4.

Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor and non-motor symptoms and loss of dopaminergic neurons of the substantia nigra. Inflammation and cell death are recognized aspects of PD suggesting that strategies to monitor and modify these processes may improve the management of the disease. Inflammasomes are pro-inflammatory intracellular pattern recognition complexes that couple these processes. The NLRP3 inflammasome responds to sterile triggers to initiate pro-inflammatory processes characterized by maturation of inflammatory cytokines, cytoplasmic membrane pore formation, vesicular shedding, and if unresolved, pyroptotic cell death. Histologic analysis of tissues from PD patients and individuals with nigral cell loss but no diagnosis of PD identified elevated expression of inflammasome-related proteins and activation-related "speck" formation in degenerating mesencephalic tissues compared with controls. Based on previous reports of circulating inflammasome proteins in patients suffering from heritable syndromes caused by hyper-activation of the NLRP3 inflammasome, we evaluated PD patient plasma for evidence of inflammasome activity. Multiple circulating inflammasome proteins were detected almost exclusively in extracellular vesicles indicative of ongoing inflammasome activation and pyroptosis. Analysis of plasma obtained from a multi-center cohort identified elevated plasma-borne NLRP3 associated with PD status. Our findings are consistent with others indicating inflammasome activity in neurodegenerative disorders. Findings suggest mesencephalic inflammasome protein expression as a histopathologic marker of early-stage nigral degeneration and suggest plasma-borne inflammasome-related proteins as a potentially useful class of biomarkers for patient stratification and the detection and monitoring of inflammation in PD.
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http://dx.doi.org/10.1038/s41531-020-00147-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7782812PMC
January 2021

Evaluation of a Mainstream Model of Genetic Testing for Men With Prostate Cancer.

JCO Oncol Pract 2021 02 24;17(2):e204-e216. Epub 2020 Sep 24.

Medical Oncology, Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia.

Purpose: To identify the approximately 12% with inherited cancer predisposition, all men with metastatic prostate cancer (mPC) should be offered germline genetic testing. This guides treatment choices and impacts cancer prevention in the family. Limited genetic services globally present a barrier to testing. This study tested a potential solution, "mainstreaming," where counseling and testing are performed by the patient's oncologist.

Patients And Methods: Men with mPC at three Australian sites were offered germline genetic testing at their medical oncology appointment. Panel testing (, , , , , , , , , , , , , , , and ) was performed on saliva/blood (Invitae, San Francisco, CA). Primary outcomes were clinician and patient satisfaction. Secondary outcomes included mutation rates and resource allocation.

Results: Of 66 men offered testing, 63 (95%) accepted. Four pathogenic variants were identified (two , one , and one ). Fifty patients and nine clinicians completed questionnaires. Satisfaction was high. All patients were pleased to have had testing overall, 98% (46 of 47) to have had testing at their usual oncology appointment, and all to receive results from their usual specialist, rather than a separate genetics appointment. A total of 88% (7 of 8) of clinicians felt confident, and all were satisfied with mainstreaming. Mainstreaming was resource efficient, requiring 87% fewer genetic consultations than traditional genetic counseling.

Conclusion: This study demonstrates that mainstreaming of men with mPC is feasible, resource efficient, and satisfactory for clinicians and patients. Widespread implementation as standard of care would facilitate timely access to genetic testing for men with mPC.
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http://dx.doi.org/10.1200/OP.20.00399DOI Listing
February 2021

The effect of botulinum toxin on ureteral inflammation.

World J Urol 2021 Jun 21;39(6):2197-2204. Epub 2020 Jul 21.

Department of Urology, Dartmouth-Hitchcock, 1 Medical Center Dr, Lebanon, NH, USA.

Purpose: The impact of onabotulinum toxin type A (BoNT-A) on bladder afferent nerve pathways and chemosensory functions is an active area of investigation. There may be a role for BoNT-A in disorders of the ureter; however, no histologic studies have assessed the effects of BoNT-A on ureteral tissue. Our objective was to develop an animal model of ureteral inflammation and determine the impact of ureteral BoNT-A instillation on known mechanisms of inflammation.

Methods: The safety and feasibility of a novel animal model of ureteral inflammation was assessed. Through open cystotomy, the effect of ureteral BoNT-A instillation on inflammation was determined through H&E, masson's trichrome, Ki-67 stain, and prostaglandin E (PGE) synthase expression, a known marker of pain and inflammation in ureteral tissue. Urothelial microstructure was assessed using electron microscopy and standard histologic techniques.

Results: All experiments were carried to completion, and no systemic signs of botulinum toxicity were seen. BoNT-A exposure was associated with a decrease in PGE synthase expression in a dose-dependent fashion. BoNT-A exposure was not found to impact collagen deposition or cell proliferation. Disruption of tight junctions between urothelial cells was observed under conditions of inflammation.

Conclusion: We describe the feasibility of a novel in vivo model of ureteral inflammation and report the first histologic study of the effects of BoNT-A on the ureter. Preliminary findings show that BoNT-A attenuates ureteral PGE synthase expression under conditions of inflammation. The application of BoNT-A may provide anti-inflammatory and analgesic effects in the context of ureteral disorders.
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http://dx.doi.org/10.1007/s00345-020-03365-yDOI Listing
June 2021

Slc6a3-dependent expression of a CAPS-associated Nlrp3 allele results in progressive behavioral abnormalities and neuroinflammation in aging mice.

J Neuroinflammation 2020 Jul 17;17(1):213. Epub 2020 Jul 17.

Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, 1 Rope Ferry Road, Hanover, NH, 03755, USA.

Background: An association between neuroinflammation and age-related neurologic disorders has been established but the molecular mechanisms and cell types involved have not been thoroughly characterized. Activity of the proinflammatory NLRP3 inflammasome is implicated in Alzheimer's and Parkinson's disease and our recent studies in patients suggest that dopaminergic neurons within the degenerating mesencephalon express NLRP3 throughout the progression of PD. Here, we directly test the impact of enhanced inflammasome activity in mesencephalic neurons by characterizing motor function, tissue integrity, and neuroinflammation in aging mice harboring hyperactivating mutations within the endogenous murine Nlrp3 locus, enabled only in cells expressing the dopaminergic neuron-specific Slc6a3 promoter.

Methods: We compared mice harboring inducible alleles encoding the cryopyrin-associated periodic syndrome activating mutations Nlrp3 and Nlrp3 inserted into the endogenous mouse Nlrp3 locus. Tissue specific expression was driven by breeding these animals with mice expressing Cre recombinase under the control of the dopaminergic neuron-specific Slc6a3 promoter. The experimental mice, designed to express hyperactive NLRP3 only when the endogenous mouse Nlrp3 promotor is active in dopaminergic neurons, were analyzed throughout 18 months of aging using longitudinal motor function assessments. Biochemical and histologic analyses of mesencephalic tissues were conducted in 1- and 18-month-old animals.

Results: We observed progressive and significant deficits in motor function in animals expressing Nlrp3, compared with animals expressing Nlrp3 and Nlrp3. Age-dependent neuroinflammatory changes in the mesencephalon were noted in all animals. Analysis of GFAP-immunoreactive astrocytes in the substantia nigra revealed a significant increase in astrocyte number in animals expressing Nlrp3 compared with Nlrp3 and Nlrp3. Further analysis of Nlrp3 striatal tissues indicated genotype specific gliosis, elevated Il1b expression, and both morphologic and gene expression indicators of proinflammatory A1 astrocytes.

Conclusions: Dopaminergic neurons have the potential to accumulate NLRP3 inflammasome activators with age, including reactive oxygen species, dopamine metabolites, and misfolded proteins. Results indicate the Nlrp3 locus is active in dopaminergic neurons in aging mice, and that the hyperactive Nlrp3 allele can drive neuroinflammatory changes in association with progressive behavioral deficits. Findings suggest neuronal NLRP3 inflammasome activity may contribute to neuroinflammation observed during normal aging and the progression of neurologic disorders.
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http://dx.doi.org/10.1186/s12974-020-01866-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7368774PMC
July 2020

Challenges and strategies proposed by genetic health professionals to assist with family communication.

Eur J Hum Genet 2019 11 12;27(11):1630-1638. Epub 2019 Jun 12.

Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Randwick, NSW, Australia.

Hereditary genetic conditions have implications for the whole family and therefore genetic health professionals (GHPs) interact with multiple family members, sometimes individually and sometimes in aggregate. Family communication is important to ensure dissemination of genetic information to potentially affected relatives and to facilitate supportive family interactions around genetic testing and risk management decisions. Yet, little is known about how GHPs perceive and manage these interactions. A total of 73 GHPs working across Australian cancer genetic clinics participated in semi-structured focus groups or interviews to elucidate what aspects of family communication they found most challenging, the strategies they used, and whether current academic training provides sufficient guidance to address familial concerns. Patients' lack of understanding about the importance of communicating genetic information to at-risk relatives was the most common challenge reported. GHPs reported that the patients' concern for their families' emotional responses as well as wider family system challenges (e.g. estrangement) affected family communication. Common strategies during consultations included structuring appointments logistically to account for family dynamics and post-consultation use of family letters and follow-up appointments. GHPs generally felt equipped with the skills and training provided to address patient concerns, but also desired upskilling in techniques relating to systemic family issues and behavioural change. Reflective practice strategies were requested by geneticists and nurses to foster therapeutic skill usage. Additional family therapy training while on the job may be beneficial in order to meet current challenges faced in clinical practice and can be provided as further professional development.
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http://dx.doi.org/10.1038/s41431-019-0447-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6871519PMC
November 2019

expression in mesencephalic neurons and characterization of a rare polymorphism associated with decreased risk of Parkinson's disease.

NPJ Parkinsons Dis 2018 15;4:24. Epub 2018 Aug 15.

1Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth and Dartmouth-Hitchcock Medical Center, Lebanon, NH USA.

Neuroinflammation is a well-characterized pathophysiology occurring in association with the progression of Parkinson's disease. Characterizing the cellular and molecular basis of neuroinflammation is critical to understanding its impact on the incidence and progression of PD and other neurologic disorders. Inflammasomes are intracellular pro-inflammatory pattern-recognition receptors capable of initiating and propagating inflammation. These cellular complexes are well characterized in the innate immune system and activity of the NLRP3 inflammasome has been reported in microglia. NLRP3 inflammasome activity has been associated with Alzheimer's disease, and recent reports, from our laboratory and others, indicate that is required for neuroinflammation and nigral cell loss in animal models of PD. has not yet been characterized in PD patients. Here we characterize in PD using immunohistologic and genetic approaches. Histologic studies revealed elevated expression in mesencephalic neurons of PD patients. Analysis of exome sequencing data for genetic variation of identified multiple single-nucleotide polymorphisms (SNPs) including rs7525979 that was associated with a significantly reduced risk of developing PD. Mechanistic studies conducted in HEK293 cells indicated that the synonymous SNP, rs7525979, alters the efficiency of translation impacting NLRP3 protein stability, ubiquitination state, and solubility. These data provide evidence that dopaminergic neurons are a cell-of-origin for inflammasome activity in PD and are consistent with recent animal studies, suggesting that inflammasome activity may impact the progression of PD.
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http://dx.doi.org/10.1038/s41531-018-0061-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6093937PMC
August 2018

Editor's Highlight: Nlrp3 Is Required for Inflammatory Changes and Nigral Cell Loss Resulting From Chronic Intragastric Rotenone Exposure in Mice.

Toxicol Sci 2017 09;159(1):64-75

Department of Molecular and Systems Biology.

Complex interactions between genetic and environmental factors are widely believed to underlie the incidence and progression of Parkinson's disease (PD). Rotenone is a naturally occurring metabolic toxin employed as an insecticide and piscicide identified as a risk factor for the development of PD in agricultural workers. The Nlrp3 inflammasome is an intracellular mediator that can initiate an inflammatory cascade in response to cellular stress. Reports by others indicating that NLRP3 expression was detectable in tissues obtained from Alzheimer's disease patients and that the PD-associated protein α-synuclein could activate inflammasomes in cultured glial cells, prompted us to test the prediction that Nlrp3 was required for the development of Parkinson's-like changes resulting from rotenone exposure in mice. We exposed wild type and Nlrp3-/- mice to chronic low doses of intragastric rotenone and conducted longitudinal behavioral and serum cytokine analysis followed by evaluation of neuroinflammatory and neurodegenerative endpoints in brain tissues. We observed progressive rotenone-dependent changes in serum cytokine levels and circulating leukocytes in wild type mice not observed in Nlrp3-/- mice. Analysis of brain tissues revealed Nlrp3-dependent neuroinflammation and nigral cell loss in mice exposed to rotenone as compared with mice exposed to vehicle alone. Together, our findings provide compelling evidence of a role for Nlrp3 in nigral degeneration and neuroinflammation resulting from systemic rotenone exposure and suggest that the suppression of NLRP3 activity may be a rational neuroprotective strategy for toxin-associated PD.
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http://dx.doi.org/10.1093/toxsci/kfx117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837210PMC
September 2017

Family Communication, Risk Perception and Cancer Knowledge of Young Adults from BRCA1/2 Families: a Systematic Review.

J Genet Couns 2017 Dec 30;26(6):1179-1196. Epub 2017 Jun 30.

Behavioral Sciences Unit Proudly Supported by the Kids with Cancer Foundation, Kids Cancer Centre, Level 1 South, Sydney Children's Hospital, High Street, Randwick, NSW, 2031, Australia.

Understanding challenges in familial communication of cancer risk has informed genetic service delivery. Parent-child interactions have received considerable attention, but few studies focus on young adulthood experiences within BRCA1/2 families. Young adults are approaching, or at a life stage where awareness of hereditary cancer risk is vital for informed choice of risk management options. This review assesses family communication, risk perception and cancer knowledge held by 18-40 year old individuals who have a parent with a BRCA1/2 gene mutation or carry the gene mutation themselves. Thirteen papers met the inclusion criteria. One utilized a 'mixed methods' methodology and the remaining used a qualitative approach. Findings were synthesized into themes and reported narratively. In general, parents are communicating openly about genetic risk with young adult offspring, but there is evidence that some young adults are withholding information from their parents about their own test results. Risk perception is influenced by a family history of cancer, childbearing plans and health providers' advice. Misconceptions about genetic risk appear to be common and gaps in hereditary cancer knowledge are evident. It is unclear whether incorrect knowledge was passed from parents to offspring. Health providers need to provide developmentally appropriate services for emerging adults (18-25 years old), with particular support in navigating through risk management options.
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http://dx.doi.org/10.1007/s10897-017-0125-4DOI Listing
December 2017

PDGF Engages an E2F-USP1 Signaling Pathway to Support ID2-Mediated Survival of Proneural Glioma Cells.

Cancer Res 2016 05 7;76(10):2964-76. Epub 2016 Mar 7.

Department of Genetics, Dartmouth College, Hanover, New Hampshire. Norris Cotton Cancer Center, Dartmouth College, Hanover, New Hampshire. Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire. Department of Pediatrics, Dartmouth College, Hanover, New Hampshire.

Glioblastoma is the most aggressive primary brain tumor and responds poorly to currently available therapies. Transcriptomic characterization of glioblastoma has identified distinct molecular subtypes of glioblastoma. Gain-of-function alterations leading to enhanced platelet-derived growth factor (PDGF) signaling are commonly observed in the proneural subtype of glioblastoma and can drive gliomagenesis. However, little is known about the downstream effectors of PDGF signaling in glioblastoma. Using a mouse model of proneural glioma and comparative transcriptomics, we determined that PDGF signaling upregulated ubiquitin-specific peptidase 1 (Usp1) to promote the survival of murine proneural glioma cells. Mechanistically, we found that PDGF signaling regulated the expression of the E2F transcription factors, which directly bound to and activated Usp1 Furthermore, PDGF-mediated expression of USP1 led to the stabilization of Inhibitor of DNA-binding 2 (ID2), which we found to be required for glioma cell survival. Genetic ablation of Id2 delayed tumor-induced mortality, and pharmacologic inhibition of USP1, resulting in decreased ID2 levels, also delayed tumorigenesis in mice. Notably, decreased USP1 expression was associated with prolonged survival in patients with proneural glioblastoma, but not with other subtypes of glioblastoma. Collectively, our findings describe a signaling cascade downstream of PDGF that sustains proneural glioblastoma cells and suggest that inhibition of the PDGF-E2F-USP1-ID2 axis could serve as a therapeutic strategy for proneural glioblastoma featuring increased PDGF signaling. Cancer Res; 76(10); 2964-76. ©2016 AACR.
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http://dx.doi.org/10.1158/0008-5472.CAN-15-2157DOI Listing
May 2016

Acute pancreatitis accelerates initiation and progression to pancreatic cancer in mice expressing oncogenic Kras in the nestin cell lineage.

PLoS One 2011 28;6(11):e27725. Epub 2011 Nov 28.

Department of Medicine, Dartmouth Medical School, Hanover, New Hampshire, United States of America.

Targeting of oncogenic Kras to the pancreatic Nestin-expressing embryonic progenitor cells and subsequently to the adult acinar compartment and Nestin-expressing cells is sufficient for the development of low grade pancreatic intraepithelial neoplasia (PanIN) between 2 and 4 months. The mice die around 6 month-old of unrelated causes, and it is therefore not possible to assess whether the lesions will progress to carcinoma. We now report that two brief episodes of caerulein-induced acute pancreatitis in 2 month-old mice causes rapid PanIN progression and pancreatic ductal adenocarcinoma (PDAC) development by 4 months of age. These events occur with similar frequency as observed in animals where the oncogene is targeted during embryogenesis to all pancreatic cell types. Thus, these data show that oncogenic Kras-driven PanIN originating in a non-ductal compartment can rapidly progress to PDAC when subjected to a brief inflammatory insult.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0027725PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3225359PMC
April 2012

Deletion of Rb accelerates pancreatic carcinogenesis by oncogenic Kras and impairs senescence in premalignant lesions.

Gastroenterology 2011 Sep 27;141(3):1091-101. Epub 2011 May 27.

Department of Medicine, Department of Pharmacology, and Toxicology, Dartmouth Medical School, Hanover, New Hampshire, USA.

Background & Aims: Rb1 encodes a cell-cycle regulator that is functionally disrupted in most human cancers. Pancreatic ductal adenocarcinomas (PDACs) have a high frequency of mutations in KRAS and INK4A/CDKN2A that might allow cells to bypass the regulatory actions of retinoblastoma (RB). To determine the role of loss of RB function in PDAC progression, we investigated the effects of Rb disruption during pancreatic malignant transformation initiated by oncogenic Kras.

Methods: We generated mice with pancreas-specific disruption of Rb, in the absence or presence of oncogenic Kras, to examine the role of RB in pancreatic carcinogenesis.

Results: In the presence of oncogenic Kras, loss of Rb from the pancreatic epithelium accelerated formation of pancreatic intraepithelial neoplasia (PanIN), increased the frequency of cystic neoplasms, and promoted rapid progression toward PDAC. Early stage cancers were characterized by acute pancreatic inflammation, associated with up-regulation of proinflammatory cytokines within the pancreas. Despite the presence of markers associated with oncogene-induced senescence, low-grade PanIN were highly proliferative and expressed high levels of p53. Pancreatic cancer cell lines derived from these mice expressed high levels of cytokines, and transcriptional activity of p53 was impaired.

Conclusions: Rb encodes a tumor suppressor that attenuates progression of oncogenic Kras-induced carcinogenesis in the pancreas by mediating the senescence response and promoting activity of the tumor suppressor p53.
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http://dx.doi.org/10.1053/j.gastro.2011.05.041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3163782PMC
September 2011

Acute pancreatitis markedly accelerates pancreatic cancer progression in mice expressing oncogenic Kras.

Biochem Biophys Res Commun 2009 May 16;382(3):561-5. Epub 2009 Mar 16.

Department of Medicine, Dartmouth Medical School, Hanover, NH 03755, USA.

Chronic pancreatitis increases by 16-fold the risk of developing pancreatic ductal adenocarcinoma (PDAC), one of the deadliest human cancers. It also appears to accelerate cancer progression in genetically engineered mouse models. We now report that in a mouse model where oncogenic Kras is activated in all pancreatic cell types, two brief episodes of acute pancreatitis caused rapid PanIN progression and accelerated pancreatic cancer development. Thus, a brief inflammatory insult to the pancreas, when occurring in the context of oncogenic Kras(G12D), can initiate a cascade of events that dramatically enhances the risk for pancreatic malignant transformation.
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http://dx.doi.org/10.1016/j.bbrc.2009.03.068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2927854PMC
May 2009
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