Office of Testing and Research

Silver Spring, MD, United States

Office of Testing and Research

Silver Spring, MD, United States
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Liu F.,National Center for Toxicological Research (NCTR) | Patterson T.A.,National Center for Toxicological Research (NCTR) | Sadovova N.,Toxicologic Pathology Associates | Zhang X.,National Center for Toxicological Research (NCTR) | And 6 more authors.
Toxicological Sciences | Year: 2013

Ketamine, a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist, is frequently used in pediatric general anesthesia. Accumulating evidence from animal experiments has demonstrated that ketamine causes neuronal cell death during the brain growth spurt. To elucidate the underlying mechanisms associated with ketamine-induced neuronal toxicity and search for approaches or agents to prevent ketamine's adverse effects on the developing brain, a primary nerve cell culture system was utilized. Neurons harvested from the forebrain of newborn rats were maintained under normal control conditions or exposed to either ketamine (10μM) or ketamine plus l-carnitine (an antioxidant; 1-100μM) for 24h, followed by a 24-h withdrawal period. Ketamine exposure resulted in elevated NMDA receptor (NR1) expression, increased generation of reactive oxygen species (ROS) as indicated by higher levels of 8-oxoguanine production, and enhanced neuronal damage. Coadministration of l-carnitine significantly diminished ROS generation and provided near complete protection of neurons from ketamine-induced cell death. NMDA receptors regulate channels that are highly permeable to calcium, and calcium imaging data demonstrated that neurons exposed to ketamine had a significantly elevated amplitude of calcium influx and higher intracellular free calcium concentrations ([Ca2+]i) evoked by NMDA (50μM), compared with control neurons. These findings suggest that prolonged ketamine exposure produces an increase in NMDA receptor expression (compensatory upregulation), which allows for a higher/toxic influx of calcium into neurons once ketamine is removed from the system, leading to elevated ROS generation and neuronal cell death. l-Carnitine appears to be a promising agent in preventing or reversing ketamine's toxic effects on neurons at an early developmental stage. Published by Oxford University Press 2012.

Sarkar S.,National Center for Toxicological Research (NCTR) | Mann D.,Wayne State University | Bowyer J.F.,National Center for Toxicological Research (NCTR) | Hanig J.P.,Office of Testing and Research | And 3 more authors.
Current Neurovascular Research | Year: 2014

Although selective neurodegeneration of nigro-striatal dopaminergic neurons is widely accepted as a cause of Parkinson's disease (PD), the role of vascular components in the brain in PD pathology is not well understood. However, the neurodegeneration seen in PD is known to be associated with neuroinflammatory- like changes that can affect or be associated with brain vascular function. Thus, dysfunction of the capillary endothelial cell component of neurovascular units present in the brain may contribute to the damage to dopaminergic neurons that occurs in PD. An animal model of PD employing acute, sub-acute and chronic exposures of mice to methyl-phenyl-tetrahydropyridine (MPTP) was used to determine the extent to which brain vasculature may be damaged in PD. Fluoro-Turquoise gelatin labeling of microvessels and endothelial cells was used to determine the extent of vascular damage produced by MPTP. In addition, tyrosine hydroxylase (TH) and NeuN were employed to detect and quantify dopaminergic neuron damage in the striatum (CPu) and substantia nigra (SNc). Gliosis was evaluated through GFAP immunohistochemistry. MPTP treatment drastically reduced TH immunoreactive neurons in the SNc (20.68±2.83 in acute; 22.98±2.14 in sub-acute; 10.20 ±2.24 in chronic vs 34.88 ±2.91in controls; p<0.001). Similarly, TH immunoreactive terminals were dramatically reduced in the CPu of MPTP treated mice. Additionally, all three MPTP exposures resulted in a decrease in the intensity, length, and number of vessels in both CPu and SNc. Degenerative vascular changes such as endothelial cell 'clusters' were also observed after MPTP suggesting that vasculature damage may be modifying the availability of nutrients and exposing blood cells and/or toxic substances to neurons and glia. In summary, vascular damage and degeneration could be an additional exacerbating factor in the progression of PD, and therapeutics that protect and insure vascular integrity may be novel treatments for PD. © 2014 Bentham Science Publishers.

PubMed | Office of Biotechnology Products and Office of Testing and Research
Type: | Journal: BioMed research international | Year: 2016

Formulating appropriate storage conditions for biopharmaceutical proteins is essential for ensuring their stability and thereby their purity, potency, and safety over their shelf-life. Using a model murine IgG3 produced in a bioreactor system, multiple formulation compositions were systematically explored in a DoE design to optimize the stability of a challenging antibody formulation worst case. The stability of the antibody in each buffer formulation was assessed by UV/VIS absorbance at 280nm and 410nm and size exclusion high performance liquid chromatography (SEC) to determine overall solubility, opalescence, and aggregate formation, respectively. Upon preliminary testing, acetate was eliminated as a potential storage buffer due to significant visible precipitate formation. An additional 2(4) full factorial DoE was performed that combined the stabilizing effect of arginine with the buffering capacity of histidine. From this final DoE, an optimized formulation of 200mM arginine, 50mM histidine, and 100mM NaCl at a pH of 6.5 was identified to substantially improve stability under long-term storage conditions and after multiple freeze/thaw cycles. Thus, our data highlights the power of DoE based formulation screening approaches even for challenging monoclonal antibody molecules.

PubMed | Office of Biotechnology Products, U.S. National Institute of Standards and Technology and Office of Testing and Research
Type: Journal Article | Journal: Journal of pharmaceutical sciences | Year: 2015

Consistent high-quality antibody yield is a key goal for cell culture bioprocessing. This endpoint is typically achieved in commercial settings through product and process engineering of bioreactor parameters during development. When the process is complex and not optimized, small changes in composition and control may yield a finished product of less desirable quality. Therefore, changes proposed to currently validated processes usually require justification and are reported to the US FDA for approval. Recently, design-of-experiments-based approaches have been explored to rapidly and efficiently achieve this goal of optimized yield with a better understanding of product and process variables that affect a products critical quality attributes. Here, we present a laboratory-scale model culture where we apply a Plackett-Burman screening design to parallel cultures to study the main effects of 11 process variables. This exercise allowed us to determine the relative importance of these variables and identify the most important factors to be further optimized in order to control both desirable and undesirable glycan profiles. We found engineering changes relating to culture temperature and nonessential amino acid supplementation significantly impacted glycan profiles associated with fucosylation, -galactosylation, and sialylation. All of these are important for monoclonal antibody product quality.

Sapsford K.E.,Center for Devices and Radiological Health | Lauritsen K.,Office of the Commissioner | Tyner K.M.,Office of Testing and Research
Therapeutic Delivery | Year: 2012

The US FDA is the US agency responsible for regulating intelligent drug-delivery systems (IDDS). IDDS can be classified as a device, drug, biologic or combination product. In this perspective, the current regulatory framework for IDDS and future perspectives on how the field is expected to evolve from a regulatory standpoint is discussed. © 2012 Future Science Ltd.

Sarkar S.,National Center for Toxicological Research (NCTR) | Chigurupati S.,National Center for Toxicological Research (NCTR) | Raymick J.,Toxicology Pathology Associates | Mann D.,Wayne State University | And 6 more authors.
NeuroToxicology | Year: 2014

Parkinson's disease (PD) is a progressive motor disease of unknown etiology in the majority of cases. The clinical features of PD emerge due to selective degeneration of dopamine (DA) neurons in the substantia nigra pars compacta (SNc), which project to the caudate putamen (CPu) where they release DA. In the current in vivo mouse model study, we tested trehalose for its ability to protect against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced damage to DA neurons. Trehalose is a naturally occurring disaccharide present in plants and animals and appears capable of protecting cells against various environmental stresses. The effect of trehalose is likely due to its action as a pharmacological chaperone which promotes protein stability. In the present study, there were four treatment groups: saline only (control); probenecid only; MPTP. +. probenecid; and trehalose. +. MPTP. +. probenecid. MPTP-induced losses in tyrosine hydroxylase and DA transporter immunoreactivity in the ventral midbrain SNc and CPu were significantly reduced by trehalose. Decreases in CPu dopamine levels produced by MPTP were also blocked by trehalose. Microglial activation and astrocytic hypertrophy induced by MPTP were greatly reduced by trehalose, indicating protection against neuroinflammation. These effects are commensurate with the observed trehalose sparing of motor deficits produced by MPTP in this mouse model. Two tight junctional proteins, ZO-1 and occludin, are downregulated following MPTP treatment and trehalose blocks this effect. Likewise, the glucose transporter-1 that is expressed in brain endothelial cells is also protected by trehalose from MPTP-induced down-regulation. This study is the first to demonstrate using fluoro-turoquoise FT gel perfusion techniques, the protection afforded by trehalose from MPTP-induced damage to microvessels and endothelial and suggests that trehalose therapy may have the potential to slow or ameliorate PD pathology. © 2014.

Louie A.,Florida College | Boyne M.T.,Office of Testing and Research | Patel V.,Center for Drug Evaluation and Research | Huntley C.,U.S. National Institutes of Health | And 8 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2015

A recent report found that generic parenteral vancomycin products may not have in vivo efficacies equivalent to those of the innovator in a neutropenic murine thigh infection model despite having similar in vitro microbiological activities and murine serum pharmacokinetics. We compared the in vitro and in vivo activities of six of the parenteral vancomycin products available in the United States. The in vitro assessments for the potencies of the vancomycin products included MIC/minimal bactericidal concentration (MBC) determinations, quantifying the impact of human and murine serum on the MIC values, and time-kill studies. Also, the potencies of the vancomycin products were quantified with a biological assay, and the human and mouse serum protein binding rates for the vancomycin products were measured. The in vivo studies included dose-ranging experiments with the 6 vancomycin products for three isolates of Staphylococcus aureus in a neutropenic mouse thigh infection model. The pharmacokinetics of the vancomycin products were assessed in infected mice by population pharmacokinetic modeling. No differences were seen across the vancomycin products with regard to any in vitro evaluation. Inhibitory sigmoid maximal bacterial kill (Emax) modeling of the relationship between vancomycin dosage and the killing of the bacteria in mice in vivo yielded similar Emax and EC50 (drug exposure driving one-half Emax) values for bacterial killing. Further, there were no differences in the pharmacokinetic clearances of the 6 vancomycin products from infected mice. There were no important pharmacodynamic differences in the in vitro or in vivo activities among the six vancomycin products evaluated. © 2015 American Society for Microbiology. All Rights Reserved.

PubMed | Div. II, Office of Testing and Research and Div. of Post Marketing Activities II
Type: | Journal: Biotechnology progress | Year: 2016

Linkage of upstream cell culture with downstream processing and purification is an aspect of Quality by Design crucial for efficient and consistent production of high quality biopharmaceutical proteins. In a previous Plackett-Burman screening study of parallel bioreactor cultures we evaluated main effects of 11 process variables, such as agitation, sparge rate, feeding regimens, dissolved oxygen set point, inoculation density, supplement addition, temperature, and pH shifts. In this follow-up study, we observed linkages between cell culture process parameters and downstream capture chromatography performance and subsequent antibody attributes. In depth analysis of the capture chromatography purification of harvested cell culture fluid yielded significant effects of upstream process parameters on host cell protein abundance and behavior. A variety of methods were used to characterize the antibody both after purification and buffer formulation. This analysis provided insight in to the significant impacts of upstream process parameters on aggregate formation, impurities, and protein structure. This report highlights the utility of linkage studies in identifying how changes in upstream parameters can impact downstream critical quality attributes. 2016 American Institute of Chemical Engineers Biotechnol. Prog., 2016.

Miesegaes G.R.,Office of Biotechnology Products | Lute S.,Office of Biotechnology Products | Strauss D.M.,Eli Lilly and Company | Read E.K.,Office of Biotechnology Products | And 6 more authors.
Biotechnology and Bioengineering | Year: 2012

Traditionally, post-production culture harvest capture of therapeutic monoclonal antibodies (mAbs) is performed using Protein A chromatography. We investigated the efficiency and robustness of cation exchange chromatography (CEX) in an effort to evaluate alternative capture methodologies. Up to five commercially available CEX resins were systematically evaluated using an experimentally optimized buffer platform and a design-of-experiment (DoE) approach for their ability to (a) capture a model mAb with a neutral isoelectric point, (b) clear three model viruses (porcine parvovirus, CHO type-C particles, and a bacteriophage). This approach identified a narrow operating space where yield, purity, and viral clearance were optimal under a CEX capture platform, and revealed trends between viral clearance of PPV and product purity (but not yield). Our results suggest that after unit operation optimization, CEX can serve as a suitable capture step. © 2012 Wiley Periodicals, Inc.

Levy M.J.,Office of Testing and Research | Gucinski A.C.,Office of Testing and Research | Sommers C.D.,Office of Testing and Research | Ghasriani H.,Office of Testing and Research | And 3 more authors.
Analytical and Bioanalytical Chemistry | Year: 2014

The FDA has approved more than 100 protein and peptide drugs with hundreds more in the pipeline (Lanthier et al. in Nat Rev Drug Discov 7(9):733-737, 2008). Many of these originator biologic products are now coming off patent and are being manufactured by alternate methods than the innovator as follow-on drugs. Because changes to the production method often lead to subtle differences (e.g., degradation products, different posttranslational modifications or impurities) in the therapeutic (Schiestl et al. in Nat Biotechnol 29(4):310-312, 2011), there is a critical need to define techniques to test and insure the quality of these drugs. In addition, the emergence of protein therapeutics manufactured by unapproved methodologies presents an ongoing and growing regulatory challenge. In this work, high-resolution mass spectrometry was used to determine the presence or absence of posttranslational modifications for one FDA-approved and three foreign-sourced, unapproved filgrastim products. Circular dichroism (CD) was used to compare the secondary structure and probe the temperature stability of these products. Native 2D 1H,15N-heteronuclear singular quantum coherence (HSQC) NMR test was applied to these samples to compare the higher-order structure of the four products. Finally, a cell proliferation assay was performed on the filgrastims to compare their bioactivity, and stressed filgrastim was tested in the bioassay to better understand the effects of changes in protein structure on activity. The results showed that orthogonal approaches are capable of characterizing the physiochemical properties of this protein drug and assessing the impact of structural changes on filgrastim purity and potency. © 2013 Springer-Verlag Berlin Heidelberg (outside the USA).

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