Publications by authors named "Robin Webb"

17 Publications

  • Page 1 of 1

Neural Stem Cell Extracellular Vesicles Disrupt Midline Shift Predictive Outcomes in Porcine Ischemic Stroke Model.

Transl Stroke Res 2020 08 6;11(4):776-788. Epub 2019 Dec 6.

Regenerative Bioscience Center, University of Georgia, Athens, GA, 30602, USA.

Magnetic resonance imaging (MRI) is a clinically relevant non-invasive imaging tool commonly utilized to assess stroke progression in real time. This study investigated the utility of MRI as a predictive measure of clinical and functional outcomes when a stroke intervention is withheld or provided, in order to identify biomarkers for stroke functional outcome under these conditions. Fifteen MRI and ninety functional parameters were measured in a middle cerebral artery occlusion (MCAO) porcine ischemic stroke model. Multiparametric analysis of correlations between MRI measurements and functional outcome was conducted. Acute axial and coronal midline shift (MLS) at 24 h post-stroke were associated with decreased survival and recovery measured by modified Rankin scale (mRS) and were significantly correlated with 52 measured acute (day 1 post) and chronic (day 84 post) gait and behavior impairments in non-treated stroked animals. These results suggest that MLS may be an important non-invasive biomarker that can be used to predict patient outcomes and prognosis as well as guide therapeutic intervention and rehabilitation in non-treated animals and potentially human patients that do not receive interventional treatments. Neural stem cell-derived extracellular vesicle (NSC EV) was a disruptive therapy because NSC EV administration post-stroke disrupted MLS correlations observed in non-treated stroked animals. MLS was not associated with survival and functional outcomes in NSC EV-treated animals. In contrast to untreated animals, NSC EVs improved stroked animal outcomes regardless of MLS severity.
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http://dx.doi.org/10.1007/s12975-019-00753-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7340639PMC
August 2020

Chondroitin Sulfate Glycosaminoglycan Scaffolds for Cell and Recombinant Protein-Based Bone Regeneration.

Stem Cells Transl Med 2019 06 21;8(6):575-585. Epub 2019 Jan 21.

Regenerative Bioscience Center, University of Georgia, Athens, Georgia, USA.

Bone morphogenetic protein 2 (BMP-2)-loaded collagen sponges remain the clinical standard for treatment of large bone defects when there is insufficient autograft, despite associated complications. Recent efforts to negate comorbidities have included biomaterials and gene therapy approaches to extend the duration of BMP-2 release and activity. In this study, we compared the collagen sponge clinical standard to chondroitin sulfate glycosaminoglycan (CS-GAG) scaffolds as a delivery vehicle for recombinant human BMP-2 (rhBMP-2) and rhBMP-2 expression via human BMP-2 gene inserted into mesenchymal stem cells (BMP-2 MSC). We demonstrated extended release of rhBMP-2 from CS-GAG scaffolds compared to their collagen sponge counterparts, and further extended release from CS-GAG gels seeded with BMP-2 MSC. When used to treat a challenging critically sized femoral defect model in rats, both rhBMP-2 and BMP-2 MSC in CS-GAG induced comparable bone formation to the rhBMP-2 in collagen sponge, as measured by bone volume, strength, and stiffness. We conclude that CS-GAG scaffolds are a promising delivery vehicle for controlling the release of rhBMP-2 and to mediate the repair of critically sized segmental bone defects. Stem Cells Translational Medicine 2019;8:575-585.
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http://dx.doi.org/10.1002/sctm.18-0141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6525555PMC
June 2019

Trisomy of human chromosome 21 enhances amyloid-β deposition independently of an extra copy of APP.

Brain 2018 08;141(8):2457-2474

Department of Neurodegenerative Disease, UCL Institute of Neurology, London, WC1N 3BG UK.

Down syndrome, caused by trisomy of chromosome 21, is the single most common risk factor for early-onset Alzheimer's disease. Worldwide approximately 6 million people have Down syndrome, and all these individuals will develop the hallmark amyloid plaques and neurofibrillary tangles of Alzheimer's disease by the age of 40 and the vast majority will go on to develop dementia. Triplication of APP, a gene on chromosome 21, is sufficient to cause early-onset Alzheimer's disease in the absence of Down syndrome. However, whether triplication of other chromosome 21 genes influences disease pathogenesis in the context of Down syndrome is unclear. Here we show, in a mouse model, that triplication of chromosome 21 genes other than APP increases amyloid-β aggregation, deposition of amyloid-β plaques and worsens associated cognitive deficits. This indicates that triplication of chromosome 21 genes other than APP is likely to have an important role to play in Alzheimer's disease pathogenesis in individuals who have Down syndrome. We go on to show that the effect of trisomy of chromosome 21 on amyloid-β aggregation correlates with an unexpected shift in soluble amyloid-β 40/42 ratio. This alteration in amyloid-β isoform ratio occurs independently of a change in the carboxypeptidase activity of the γ-secretase complex, which cleaves the peptide from APP, or the rate of extracellular clearance of amyloid-β. These new mechanistic insights into the role of triplication of genes on chromosome 21, other than APP, in the development of Alzheimer's disease in individuals who have Down syndrome may have implications for the treatment of this common cause of neurodegeneration.
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http://dx.doi.org/10.1093/brain/awy159DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6061702PMC
August 2018

Human Neural Stem Cell Extracellular Vesicles Improve Recovery in a Porcine Model of Ischemic Stroke.

Stroke 2018 05 12;49(5):1248-1256. Epub 2018 Apr 12.

Regenerative Bioscience Center (R.L.W., E.E.K., B.J.J., S.S., F.D.W., S.L. Stice)

Background And Purpose: Recent work from our group suggests that human neural stem cell-derived extracellular vesicle (NSC EV) treatment improves both tissue and sensorimotor function in a preclinical thromboembolic mouse model of stroke. In this study, NSC EVs were evaluated in a pig ischemic stroke model, where clinically relevant end points were used to assess recovery in a more translational large animal model.

Methods: Ischemic stroke was induced by permanent middle cerebral artery occlusion (MCAO), and either NSC EV or PBS treatment was administered intravenously at 2, 14, and 24 hours post-MCAO. NSC EV effects on tissue level recovery were evaluated via magnetic resonance imaging at 1 and 84 days post-MCAO. Effects on functional recovery were also assessed through longitudinal behavior and gait analysis testing.

Results: NSC EV treatment was neuroprotective and led to significant improvements at the tissue and functional levels in stroked pigs. NSC EV treatment eliminated intracranial hemorrhage in ischemic lesions in NSC EV pigs (0 of 7) versus control pigs (7 of 8). NSC EV-treated pigs exhibited a significant decrease in cerebral lesion volume and decreased brain swelling relative to control pigs 1-day post-MCAO. NSC EVs significantly reduced edema in treated pigs relative to control pigs, as assessed by improved diffusivity through apparent diffusion coefficient maps. NSC EVs preserved white matter integrity with increased corpus callosum fractional anisotropy values 84 days post-MCAO. Behavior and mobility improvements paralleled structural changes as NSC EV-treated pigs exhibited improved outcomes, including increased exploratory behavior and faster restoration of spatiotemporal gait parameters.

Conclusions: This study demonstrated for the first time that in a large animal model novel NSC EVs significantly improved neural tissue preservation and functional levels post-MCAO, suggesting NSC EVs may be a paradigm changing stroke therapeutic.
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http://dx.doi.org/10.1161/STROKEAHA.117.020353DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5916046PMC
May 2018

Human Neural Stem Cell Extracellular Vesicles Improve Tissue and Functional Recovery in the Murine Thromboembolic Stroke Model.

Transl Stroke Res 2018 10 28;9(5):530-539. Epub 2017 Dec 28.

ArunA Biomedical, Athens, GA, 30602, USA.

Over 700 drugs have failed in stroke clinical trials, an unprecedented rate thought to be attributed in part to limited and isolated testing often solely in "young" rodent models and focusing on a single secondary injury mechanism. Here, extracellular vesicles (EVs), nanometer-sized cell signaling particles, were tested in a mouse thromboembolic (TE) stroke model. Neural stem cell (NSC) and mesenchymal stem cell (MSC) EVs derived from the same pluripotent stem cell (PSC) line were evaluated for changes in infarct volume as well as sensorimotor function. NSC EVs improved cellular, tissue, and functional outcomes in middle-aged rodents, whereas MSC EVs were less effective. Acute differences in lesion volume following NSC EV treatment were corroborated by MRI in 18-month-old aged rodents. NSC EV treatment has a positive effect on motor function in the aged rodent as indicated by beam walk, instances of foot faults, and strength evaluated by hanging wire test. Increased time with a novel object also indicated that NSC EVs improved episodic memory formation in the rodent. The therapeutic effect of NSC EVs appears to be mediated by altering the systemic immune response. These data strongly support further preclinical development of a NSC EV-based stroke therapy and warrant their testing in combination with FDA-approved stroke therapies.
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http://dx.doi.org/10.1007/s12975-017-0599-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6132936PMC
October 2018

Pig Induced Pluripotent Stem Cell-Derived Neural Rosettes Parallel Human Differentiation Into Sensory Neural Subtypes.

Cell Reprogram 2017 04 7;19(2):88-94. Epub 2017 Mar 7.

1 Regenerative Bioscience Center, University of Georgia , Rhodes Center for Animal and Dairy Science, Athens, Georgia .

The pig is the large animal model of choice for study of nerve regeneration and wound repair. Availability of porcine sensory neural cells would conceptually allow for analogous cell-based peripheral nerve regeneration in porcine injuries of similar severity and size to those found in humans. After recently reporting that porcine (or pig) induced pluripotent stem cells (piPSCs) differentiate into neural rosette (NR) structures similar to human NRs, here we demonstrate that pig NR cells could differentiate into neural crest cells and other peripheral nervous system-relevant cell types. Treatment with either bone morphogenetic protein 4 or fetal bovine serum led to differentiation into BRN3A-positive sensory cells and increased expression of sensory neuron TRK receptor gene family: TRKA, TRKB, and TRKC. Porcine sensory neural cells would allow determination of parallels between human and porcine cells in response to noxious stimuli, analgesics, and reparative mechanisms. In vitro differentiation of pig sensory neurons provides a novel model system for neural cell subtype specification and would provide a novel platform for the study of regenerative therapeutics by elucidating the requirements for innervation following injury and axonal survival.
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http://dx.doi.org/10.1089/cell.2016.0057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016089PMC
April 2017

High content imaging quantification of multiple in vitro human neurogenesis events after neurotoxin exposure.

BMC Pharmacol Toxicol 2016 12 1;17(1):62. Epub 2016 Dec 1.

Interdisciplinary Toxicology Program, University of Georgia, Athens, GA, 30602, USA.

Background: Our objective was to test neural active compounds in a human developmental neurotoxicity (DNT) model that represents neural tube stages of vulnerability. Previously we showed that 14 days in vitro (DIV 14) was sufficient to generate cryopreserved neuronal cells for post thaw neurite recovery assays. However, short exposure and assessment may not detect toxicants that affect an early neurogenesis continuum, from a mitotic human neural progenitor (hNP) cell population through the course of neurite outgrowth in differentiating neurons. Therefore, we continuously exposed differentiating hNP cells from DIV 0 through DIV 14 to known toxicants and endocrine active compounds in order to assess at DIV 14 effects of these compounds in a human DNT maturation model for neurogenesis.

Methods: The Human DNT continuum (DIV 0 to DIV 14) was determined using immunocytochemistry for SOX1+ (proliferating hNP) and HuC/D+ (post mitotic neurons). The cumulative effects of five compounds was observed on neurite outgrowth in (βIII-tubulin+) and (HuC/D+) cells using high content imaging. All data were analyzed using a one-way ANOVA with a significance threshold of p < 0.05.

Results: During maturation in vitro, the neural cultures transitioned from uniform hNP cells (DIV 0) to predominantly mature post mitotic neuronal neurons (HuC/D+, 65%; DIV14) but also maintained a smaller population of hNP cells (SOX1+). Using this DNT maturation model system, Bis-1, testosterone, and β-estradiol inhibited neuronal maturation at micromolar levels but were unaffected by acetaminophen. β-estradiol also disrupted neurite extension at 10 μM. Treating cells in this window with Bisphenol A (BPA) significantly inhibited neurite outgrowth and branching in these continuum cultures but only at the highest concentrations tested (10 μM).

Conclusions: Cumulative effects of neurotoxicant exposure during a maturation continuum altered human neurogenesis at lower exposure levels than observed in acute exposure of static cryopreserved neurite recovery neurons cultures. Unlike prior acute studies, β-estradiol was highly toxic when present throughout the continuum and cytotoxicity was manifested starting early in the continuum via a non-estrogen receptor α (ER α) mechanism. Therefore, the effect of neural developmental neurotoxins can and should be determined during the dynamic process of human neural maturation.
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http://dx.doi.org/10.1186/s40360-016-0107-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5131404PMC
December 2016

Pig Induced Pluripotent Stem Cell-Derived Neural Rosettes Developmentally Mimic Human Pluripotent Stem Cell Neural Differentiation.

Stem Cells Dev 2015 Aug 6;24(16):1901-11. Epub 2015 May 6.

1 Regenerative Bioscience Center, University of Georgia , Rhodes Center for Animal and Dairy Science, Athens, Georgia .

For diseases of the brain, the pig (Sus scrofa) is increasingly being used as a model organism that shares many anatomical and biological similarities with humans. We report that pig induced pluripotent stem cells (iPSC) can recapitulate events in early mammalian neural development. Pig iPSC line (POU5F1(high)/SSEA4(low)) had a higher potential to form neural rosettes (NR) containing neuroepithelial cells than either POU5F1(low)/SSEA4(low) or POU5F1(low)/SSEA4(high) lines. Thus, POU5F1 and SSEA4 pluripotency marker profiles in starting porcine iPSC populations can predict their propensity to form more robust NR populations in culture. The NR were isolated and expanded in vitro, retaining their NR morphology and neuroepithelial molecular properties. These cells expressed anterior central nervous system fate markers OTX2 and GBX2 through at least seven passages, and responded to retinoic acid, promoting a more posterior fate (HOXB4+, OTX2-, and GBX2-). These findings offer insight into pig iPSC development, which parallels the human iPSC in both anterior and posterior neural cell fates. These in vitro similarities in early neural differentiation processes support the use of pig iPSC and differentiated neural cells as a cell therapy in allogeneic porcine neural injury and degeneration models, providing relevant translational data for eventual human neural cell therapies.
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http://dx.doi.org/10.1089/scd.2015.0025DOI Listing
August 2015

Bridging integrator 1 (BIN1) protein expression increases in the Alzheimer's disease brain and correlates with neurofibrillary tangle pathology.

J Alzheimers Dis 2014 ;42(4):1221-7

Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA University of Kentucky Center for Muscle Biology, University of Kentucky, Lexington, KY, USA.

Recent genome wide association studies have implicated bridging integrator 1 (BIN1) as a late-onset Alzheimer's disease (AD) susceptibility gene. There are at least 15 different known isoforms of BIN1, with many being expressed in the brain including the longest isoform (iso1), which is brain-specific and localizes to axon initial segments and nodes of Ranvier. It is currently unknown what role BIN1 plays in AD. We analyzed BIN1 protein expression from a large number (n = 71) of AD cases and controls from five different brain regions (hippocampus, inferior parietal cortex, inferior temporal cortex, frontal cortex (BA9), and superior and middle temporal gyri). We found that the amount of the largest isoform of BIN1 was significantly reduced in the AD brain compared to age-matched controls, and smaller BIN1 isoforms were significantly increased. Further, BIN1 was significantly correlated with the amount of neurofibrillary tangle (NFT) pathology but not with either diffuse or neuritic plaques, or with the amount of amyloid-β peptide. BIN1 is known to be abnormally expressed in another human disease, myotonic dystrophy, which also features prominent NFT pathology. These data suggest that BIN1 is likely involved in AD as a modulator of NFT pathology, and that this role may extend to other human diseases that feature tau pathology.
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http://dx.doi.org/10.3233/JAD-132450DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4198456PMC
July 2015

Injuries in Elite Men's Lacrosse: An Observational Study During the 2010 World Championships.

Orthop J Sports Med 2014 Jul 28;2(7):2325967114543444. Epub 2014 Jul 28.

Stanley Primary Care Centre Stanley, County Durham, UK.

Background: There are limited data on injuries sustained during men's lacrosse. As the sport gains popularity, practitioners will be more likely to treat lacrosse players.

Purpose: To analyze data from the 2010 World Lacrosse Championships.

Study Design: Descriptive epidemiology study.

Methods: This was a prospective observational study of injuries reported during the 2010 World Lacrosse Championships. An injury surveillance questionnaire was completed, and data were categorized into body part injured, diagnosis, mechanism, and time of injury.

Results: Over 9 days, 667 players from 29 countries competed in 105 games. A total of 150 injuries were sustained by 129 individuals aged 16 to 46 years. Five times more injuries occurred during games than in training (69.3% [n = 104] vs 13.3% [n = 20]; rate ratio [95% CI] = 5.2 [4.9-5.5]), resulting in 39.5 injuries per 1000 hours played. The most frequent mechanism was contact (53.3%; n = 80), including direct impact with another player (30%; n = 45), with a stick (16.7%; n = 25), or with a ball (5.3%; n = 8). Change of direction and/or speed were the most common noncontact mechanisms (27.3%; n = 41). The most frequently reported injuries were contusions (32.0%; n = 48), sprains (22.7%; n = 34), and strains (22.7%; n = 34). The lower limb was the most injured body part (50.7%; n = 76) compared with the upper limb (23.3%; n = 35; rate ratio [95% CI] = 2.2 [2.1-2.3]). The ankle was the most injured joint (14.0%; n = 21), followed by the shoulder (10.0%; n = 15).

Conclusion: As participation expands, health professionals may become more responsible for treating lacrosse players. Players are susceptible to a range of injuries. Familiarity with the common injury patterns could help treatment and prevention. Despite differences in rules during international competition, this study corroborates reports from North America.

Clinical Relevance: The epidemiology of men's lacrosse injuries needs to be documented and understood to effectively prevent injuries. The 2014 World Championships are to be held in Denver, Colorado (July 10-19, 2014), and it is important that practitioners treating players are aware of the differences in the international game. Publication of these data will allow for those planning lacrosse tournaments to do so more effectively.
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http://dx.doi.org/10.1177/2325967114543444DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4588532PMC
July 2014

Postmortem Pittsburgh Compound B (PiB) binding increases with Alzheimer's disease progression.

J Alzheimers Dis 2012 ;32(1):127-38

Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536-0230, USA.

The development of imaging reagents is of considerable interest in the Alzheimer's disease (AD) field. Some of these, such as Pittsburgh Compound B (PiB), were designed to bind to the amyloid-β peptide (Aβ), the major component of amyloid deposits in the AD brain. Although these agents were designed for imaging amyloid deposits in vivo, a major avenue of evaluation relies on postmortem cross validation with established indices of AD pathology. In this study, we evaluated changes in the postmortem binding of PiB and its relationship to other aspects of Aβ-related pathology in a series of AD cases and age-matched controls. We also examined cases of preclinical AD (PCAD) and amnestic mild cognitive impairment (MCI), both considered early points in the AD continuum. PiB binding was found to increase with the progression of the disease and paralleled increases in the less soluble forms of Aβ, including SDS-stable Aβ oligomers. Increased PiB binding and its relationship to Aβ was only significant in a brain region vulnerable to the development of AD pathology (the superior and middle temporal gyri) but not in an unaffected region (cerebellum). This implies that the amyloid deposited in disease-affected regions may possess fundamental, brain region specific characteristics that may not as yet be fully appreciated. These data support the idea that PiB is a useful diagnostic tool for AD, particularly in the early stage of the disease, and also show that PiB could be a useful agent for the discovery of novel disease-related properties of amyloid.
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http://dx.doi.org/10.3233/JAD-2012-120655DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3607315PMC
February 2013

β-Secretases, Alzheimer's Disease, and Down Syndrome.

Curr Gerontol Geriatr Res 2012 28;2012:362839. Epub 2012 Feb 28.

Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536-0230, USA.

Individuals with Down Syndrome (DS), or trisomy 21, develop Alzheimer's disease (AD) pathology by approximately 40 years of age. Chromosome 21 harbors several genes implicated in AD, including the amyloid precursor protein and one homologue of the β-site APP cleaving enzyme, BACE2. Processing of the amyloid precursor protein by β-secretase (BACE) is the rate-limiting step in the production of the pathogenic Aβ peptide. Increased amounts of APP in the DS brain result in increased amounts of Aβ and extracellular plaque formation beginning early in life. BACE dysregulation potentially represents an overlapping biological mechanism with sporadic AD and a common therapeutic target. As the lifespan for those with DS continues to increase, age-related concerns such as obesity, depression, and AD are of growing concern. The ability to prevent or delay the progression of neurodegenerative diseases will promote healthy aging and improve quality of life for those with DS.
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http://dx.doi.org/10.1155/2012/362839DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3299320PMC
August 2012

BACE2 expression increases in human neurodegenerative disease.

Am J Pathol 2012 Jan 7;180(1):337-50. Epub 2011 Nov 7.

Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536-0230, USA.

β-Secretase, the rate-limiting enzymatic activity in the production of the amyloid-β (Aβ) peptide, is a major target of Alzheimer's disease (AD) therapeutics. There are two forms of the enzyme: β-site Aβ precursor protein cleaving enzyme (BACE) 1 and BACE2. Although BACE1 increases in late-stage AD, little is known about BACE2. We conducted a detailed examination of BACE2 in patients with preclinical to late-stage AD, including amnestic mild cognitive impairment, and age-matched controls, cases of frontotemporal dementia, and Down's syndrome. BACE2 protein and enzymatic activity increased as early as preclinical AD and were found in neurons and astrocytes. Although the levels of total BACE2 mRNA were unchanged, the mRNA for BACE2 splice form C (missing exon 7) increased in parallel with BACE2 protein and activity. BACE1 and BACE2 were strongly correlated with each other at all levels, suggesting that their regulatory mechanisms may be largely shared. BACE2 was also elevated in frontotemporal dementia but not in Down's syndrome, even in patients with substantial Aβ deposition. Thus, expression of both forms of β-secretase are linked and may play a combined role in human neurologic disease. A better understanding of the normal functions of BACE1 and BACE2, and how these change in different disease states, is essential for the future development of AD therapeutics.
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http://dx.doi.org/10.1016/j.ajpath.2011.09.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3338345PMC
January 2012

Effects of nonsteroidal anti-inflammatory drugs on amyloid-beta pathology in mouse skeletal muscle.

Neurobiol Dis 2010 Sep 20;39(3):449-56. Epub 2010 May 20.

Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536-0230, USA.

Sporadic inclusion body myositis (sIBM) is a common age-related inflammatory myopathy characterized by the presence of intracellular inclusions that contain the amyloid-beta (Abeta) peptide, a derivative of the amyloid precursor protein (APP). Abeta is believed to cause Alzheimer's disease (AD), suggesting that a link may exist between the two diseases. If AD and sIBM are linked, then treatments that lower Abeta in brain may prove useful for sIBM. To test this hypothesis, transgenic mice that overexpress APP in skeletal muscle were treated for 6 months with a variety of nonsteroidal anti-inflammatory drugs (NSAIDs; naproxen, ibuprofen, carprofen or R-flurbiprofen), a subset of which reduce Abeta in brain and cultured cells. Only ibuprofen lowered Abeta in muscle, and this was not accompanied by corresponding improvements in phenotype. These results indicate that the effects of NSAIDs in the brain may be different from other tissues and that Abeta alone cannot account for skeletal muscle dysfunction in these mice.
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http://dx.doi.org/10.1016/j.nbd.2010.05.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2910117PMC
September 2010

Efficient activation of reconstructed rat embryos by cyclin-dependent kinase inhibitors.

PLoS One 2010 Mar 19;5(3):e9799. Epub 2010 Mar 19.

Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America.

Background: Over the last decade a number of species, from farm animals to rodents, have been cloned using somatic cell nuclear transfer technology (SCNT). This technique has the potential to revolutionize the way that genetically modified animals are made. In its current state, the process of SCNT is very inefficient (<5% success rate), with several technical and biological hurdles hindering development. Yet, SCNT provides investigators with powerful advantages over other approaches, such as allowing for prescreening for the desired level of transgene expression and eliminating the excess production of undesirable wild-type animals. The rat plays a significant role in biomedical research, but SCNT has been problematic for this species. In this study, we address one aspect of the problem by evaluating methods of activation in artificially constructed rat embryos.

Principal Findings: We demonstrate that treatment with a calcium ionophore (ionomycin) combined with a variety of cyclin-dependent kinase inhibitors is an effective way to activate rat embryos. This is in contrast to methods developed for the mouse embryo, which tolerates much less specific chemical treatments. Methods developed to activate mouse embryos do not translate well to rat embryos.

Conclusions: Activation methods developed for one species will not necessarily translate to another species, even if it is closely related. Further, the parthenogenic response to chemical activators is not always a reliable indicator of how reconstructed embryos will react to the same activation method. A better understanding of rat oocyte physiology, although essential for developing better models of disease, may also provide insights that will be useful for making the SCNT process more efficient.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0009799PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841646PMC
March 2010

BACE1 and BACE2 enzymatic activities in Alzheimer's disease.

J Neurochem 2010 Feb 4;112(4):1045-53. Epub 2009 Dec 4.

Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, USA.

beta-Secretase is the rate limiting enzymatic activity in the production of the amyloid-beta peptide (Abeta) and is thought to be involved in Alzheimer's disease (AD) pathogenesis. Although BACE1 (beta-site APP Cleaving Enzyme 1, EC 3.4.23.46) has received significant attention, the related BACE2 (EC 3.4.23.45) has not. Though BACE2 is also expressed in the brain, its potential role in AD has not been resolved. In this study, we compared the activities of both BACE1 and BACE2, which were isolated from the same samples of frontal cortex from both AD-affected individuals and age-matched controls. BACE1 activity showed a significant positive correlation with the amount of extractable Abeta, and BACE1 protein and activity were significantly increased in AD cases. Unexpectedly, there were substantial total amounts of BACE2 protein and enzymatic activity in the human brain. BACE2 activity did not change significantly in the AD brain, and was not related to Abeta concentration. These data indicate that BACE1 likely accounts for most of the Abeta produced in the human brain, and that BACE2 activity is not a likely contributor. However, as both forms of BACE compete for the same substrate pool, even small changes in BACE2 activity could have consequences for human disease.
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http://dx.doi.org/10.1111/j.1471-4159.2009.06528.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819564PMC
February 2010

Palate pleasers.

Authors:
Robin Webb

Diabetes Forecast 2009 Jun;62(6):46-52, 54

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June 2009