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Journal of neurochemistry (1)
Sensors (Basel, Switzerland) (1)
Armstrong, David L. (1)
Bhunia, Arun K. (1)
Ess, Daniel (1)
Geng, Tao (1)
Hahm, Byoung Kwon (1)
Hahm, Byoung-Kwon (1)
Kim, Giyoung (1)
Kothapalli, Aparna (1)
Morgan, Mark T. (1)
Nanduri, Viswaprakash (1)
Rossie, Sandra (1)
Sanchez-Ortiz, Efrain (1)
Valadez, Angela (1)
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Protein phosphatase 5 protects neurons against amyloid β toxicity
Armstrong, David L.
Journal of neurochemistry
Amyloid β (Aβ) is thought to promote neuronal cell loss in Alzheimer’s disease (AD), in part through the generation of reactive oxygen species (ROS) and subsequent activation of mitogen-activated protein kinase (MAPK) pathways. Protein phosphatase 5 (PP5) is a ubiquitously expressed serine/threonine phosphatase which has been implicated in several cell stress response pathways and shown to inactivate MAPK pathways through key dephosphorylation events. Therefore we examined whether PP5 protects dissociated embryonic rat cortical neurons in vitro from cell death evoked by Aβ. As predicted, neurons in which PP5 expression was decreased by siRNA treatment were more susceptible to Aβ toxicity. In contrast, overexpression of PP5, but not the inactive PP5 mutant, H304Q, prevented MAPK phosphorylation and neurotoxicity induced by Aβ. PP5 also prevented cell death caused by direct treatment with H2O2, but did not prevent Aβ-induced production of ROS. Thus, the neuroprotective effect of PP5 requires its phosphatase activity and lies downstream of Aβ-induced generation of ROS. In summary, our data indicate that PP5 plays a pivotal neuroprotective role against cell death induced by Aβ and oxidative stress. Consequently, PP5 might be an effective therapeutic target in AD and other neurodegenerative disorders in which oxidative stress is implicated.
PP5; protein phosphatase 5; amyloid β; Alzheimer’s disease; neuroprotection; oxidative stress
Antibody Immobilization on Waveguides Using a Flow–Through System Shows Improved Listeria monocytogenes Detection in an Automated Fiber Optic Biosensor: RAPTOR™
Morgan, Mark T.
Bhunia, Arun K.
Sensors (Basel, Switzerland)
Recent outbreaks of food borne illnesses continue to support the need for rapid and sensitive methods for detection of foodborne pathogens. A method for detecting Listeria monocytogenes in food samples was developed using an automated fiber-optic-based immunosensor, RAPTOR™. Detection of L. monocytogenes in phosphate buffered saline (PBS) was performed to evaluate both static and flow through antibody immobilization methods for capture antibodies in a sandwich assay. Subsequent detection in frankfurter samples was conducted using a flow through immobilization system. A two stage blocking using biotinylated bovine serum albumin (b-BSA) and BSA was effectively employed to reduce the non-specific binding. The sandwich assay using static or flow through mode of antibody immobilization could detect 1×103 cfu/ml in PBS. However, the effective disassociation constant Kd and the binding valences for static modes of antibody immobilization in spiked PBS samples was 4×105cfu/ml and 4.9 as compared to 7×104 cfu/ml and 3.9 for flow through method of antibody immobilization. Thus the sensitive flow-through immobilization method was used to test food samples, which could detect 5×105cfu/ml of L. monocytogenes in frankfurter sample. The responses at the lowest detectable cell numbers in the frankfurter samples was 92.5 ± 14.6 pA for L. monocytogenes to comparative responses of 27.9 ± 12.2 and 31 ± 14.04 pA obtained from Enterococcus faecalis and Lactobacillus rhamnosus (control species), respectively. The effective Kd and binding valency from spiked frankfurter samples was 4.8×105 cfu/ml and 3.1, thus showing highly sensitive detection can be achieved using the RAPTOR™ biosensor even in the presence of other bacterial species in the matrix.
Biosensor; Listeria monocytogenes; fiber optic sensor; immunosensor; RAPTOR
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