Potential value of animal microphysiological systems.

Microphysiological systems (MPS) are designed to recapitulate aspects of tissue/organ physiology in vivo, thereby providing potential value in safety and efficacy assessments of FDA-regulated products and regulatory decision-making. While there have been significant advances in the development, use, and proposals of qualification criteria for human organ MPS, there remains a gap in the development using animal tissues. Animal MPS may be of value in many areas including the study of zoonotic diseases, assessment of the safety and efficacy of animal therapeutics, and possibly reduction of the use of animals in regulatory submissions for animal therapeutics.

In vitro effects of cannabidiol and its main metabolites in mouse and human Sertoli cells.

Cannabidiol (CBD) is a major cannabinoid present in extracts of the plant Cannabis sativa (marijuana). While the therapeutic effects of CBD on epilepsy have been demonstrated, less is understood regarding its potential adverse effects. Recent studies revealed that CBD induced toxicity in the male reproductive system of animal models.

Mechanistic Evaluation of Black Cohosh Extract-Induced Genotoxicity in Human Cells.

Black cohosh extract (BCE) is marketed to women as an alternative to hormone replacement therapy for alleviating menopausal symptoms. Previous studies by the National Toxicology Program revealed that BCE induced micronuclei (MN) and a nonregenerative macrocytic anemia in rats and mice, likely caused by disruption of the folate metabolism pathway. Additional work using TK6 cells showed that BCE induced aneugenicity by destabilizing microtubules.

Performance of HepaRG and HepG2 cells in the high-throughput micronucleus assay for in vitro genotoxicity assessment.

The micronucleus (MN) assay is a core test used to evaluate genotoxic potential of xenobiotics. The traditional MN assay is usually conducted in cells lacking metabolic competency or by supplementing cultures with an exogenous rat S9 metabolic system, which creates a significant assay limitation for detecting genotoxic metabolites. Our previous study demonstrated that compared to HepG2, HepaRG cells exhibited a significantly higher level of CYP450 enzyme activities and detected a greater portion of genotoxic carcinogens requiring metabolic activation using the Comet assay.

Dr. Daniel Acosta and In Vitro toxicology at the U.S. Food and Drug Administration's National Center for Toxicological Research.

For the past five years, Dr. Daniel Acosta has served as the Deputy Director of Research at the National Center for Toxicological Research (NCTR), a principle research laboratory of the U.S.

Quantification of cellular associated graphene and induced surface receptor responses.

The use of graphene for biomedical and other applications involving humans is growing and shows practical promise. However, quantifying the graphitic nanomaterials that interact with cells and assessing any corresponding cellular response is extremely challenging. Here, we report an effective approach to quantify graphene interacting with single cells that utilizes combined multimodal-Raman and photoacoustic spectroscopy.

Analysis of mutation in the rat Pig-a assay: I) studies with bone marrow erythroid cells.

We have established a flow cytometry-based Pig-a assay for rat bone marrow erythroid cells (BMEs). The BME Pig-a assay uses a DNA-specific stain and two antibodies: one against the transmembrane transferrin receptor (CD71 marker) and the other against the GPI-anchored complement inhibitory protein (CD59 marker). In F344 male rats treated acutely with a total of 120 mg/kg of N-ethyl-N-nitrosourea (ENU) the frequency of CD59-deficient phenotypically mutant BMEs increased approximately 24-fold compared to the rats concurrently treated with the vehicle.

Analysis of mutation in the rat Pig-a assay: II. Studies with bone marrow granulocytes.

The in vivo erythrocyte Pig-a gene mutation assay measures the phenotypic loss of GPI-anchored surface markers. Molecular analysis of the marker-deficient erythrocytes cannot provide direct proof that the mutant phenotype is due to mutation in the Pig-a gene because mammalian erythrocytes lack genomic DNA. Granulocytes are nucleated cells that originate from myeloid progenitor cells in bone marrow as is the case for erythrocytes, and thus analysis of Pig-a mutation in bone marrow granulocytes can provide information about the source of mutations detected in the erythrocyte Pig-a assay.

In Vivo Rat T-Lymphocyte Pig-a Assay: Detection and Expansion of Cells Deficient in the GPI-Anchored CD48 Surface Marker for Analysis of Mutation in the Endogenous Pig-a Gene.

The Pig-a assay is being developed as an in vivo gene mutation assay for regulatory safety assessments. The assay is based on detecting mutation in the endogenous Pig-a gene of treated rats by using flow cytometry to measure changes in cell surface markers of peripheral blood cells. Here we present a methodology for demonstrating that phenotypically mutant rat T-cells identified by flow cytometry contain mutations in the Pig-a gene, an important step for validating the assay.

p53-competent cells and p53-deficient cells display different susceptibility to oxygen functionalized graphene cytotoxicity and genotoxicity.

Due to the distinctive physical, electrical, and chemical properties of graphene nanomaterials, numerous efforts pursuing graphene-based biomedical and industrial applications are underway. Oxidation of pristine graphene surfaces mitigates its otherwise hydrophobic characteristic thereby improving its biocompatibility and functionality. Yet, the potential widespread use of oxidized graphene derivatives raises concern about adverse impacts on human health.

Autophagy function and its relationship to pathology, clinical applications, drug metabolism and toxicity.

Autophagy is a cellular process that facilitates nutrient turnover and removal of expended macromolecules and organelles to maintain homeostasis. The recycling of cytosolic macromolecules and damaged organelles by autophagosomes occurs through the lysosomal degradation pathway. Autophagy can also be upregulated as a prosurvival pathway in response to stress stimuli such as starvation, hypoxia or cell damage.

The role of surface chemistry in the cytotoxicity profile of graphene.

Graphene and its derivative, because of their unique physical, electrical and chemical properties, are an important class of nanomaterials being proposed as foundational materials in nanomedicine as well as for a variety of industrial applications. A major limitation for graphene, when used in biomedical applications, is its poor solubility due to its rather hydrophobic nature. Therefore, chemical functionalities are commonly introduced to alter both its surface chemistry and biochemical activity.

Whole genome and normalized mRNA sequencing reveal genetic status of TK6, WTK1, and NH32 human B-lymphoblastoid cell lines.

Closely related TK6, WTK1, and NH32 human B-lymphoblastoid cell lines differ in their p53 functional status. These lines are used frequently in genotoxicity studies and in studies aimed at understanding the role of p53 in DNA repair. Despite their routine use, little is known about the genetic status of these cells.

Confirmation of Pig-a mutation in flow cytometry-identified CD48-deficient T-lymphocytes from F344 rats.

The Pig-a assay is used for monitoring somatic cell mutation in laboratory animals and humans. The assay detects haematopoietic cells deficient in glycosylphosphatidylinositol (GPI)-anchored protein surface markers using flow cytometry. However, given that synthesis of the protein markers (and the expression of their genes) is independent of the expression of the X-linked Pig-a gene and the function of its enzyme product, the deficiency of markers at the surface of the cells may be caused by a number of events (e.

Toxicity and efficacy of carbon nanotubes and graphene: the utility of carbon-based nanoparticles in nanomedicine.

Carbon-based nanomaterials have attracted great interest in biomedical applications such as advanced imaging, tissue regeneration, and drug or gene delivery. The toxicity of the carbon nanotubes and graphene remains a debated issue although many toxicological studies have been reported in the scientific community. In this review, we summarize the biological effects of carbon nanotubes and graphene in terms of in vitro and in vivo toxicity, genotoxicity and toxicokinetics.

In vivo genotoxicity of furan in F344 rats at cancer bioassay doses.

Furan, a potent rodent liver carcinogen, is found in many cooked food items and thus represents a human cancer risk. Mechanisms for furan carcinogenicity were investigated in male F344 rats using the in vivo Comet and micronucleus assays, combined with analysis of histopathological and gene expression changes. In addition, formamidopyrimidine DNA glycosylase (Fpg) and endonuclease III (EndoIII)-sensitive DNA damage was monitored as a measure of oxidative DNA damage.

The genetic toxicity of methylphenidate: a review of the current literature.

Attention deficit/hyperactivity disorder (ADHD), a common children's behavioral disorder, is characterized by inattention, hyperactivity and impulsivity. The disorder is thought to stem from abnormalities in the catecholamine pathway and the symptoms of the disorder have been successfully treated with methylphenidate (MPH) since the FDA approved the drug in the 1950s. MPH underwent the appropriate safety testing as part of the FDA approval process; however, a publication in 2005 that reported significant increases in cytogenetic damage in the lymphocytes of MPH-treated pediatric patients caused concern for patients and their families, the pharmaceutical industry and regulatory agencies.

Pubertal delay in male nonhuman primates (Macaca mulatta) treated with methylphenidate.

Juvenile male rhesus monkeys treated with methylphenidate hydrochloride (MPH) to evaluate genetic and behavioral toxicity were observed after 14 mo of treatment to have delayed pubertal progression with impaired testicular descent and reduced testicular volume. Further evaluation of animals dosed orally twice a day with (i) 0.5 mL/kg of vehicle (n = 10), (ii) 0.

Evaluation of p53 genotype on gene expression in the testis, liver, and heart from male C57BL/6 mice.

Our laboratory is conducting experiments designed to characterize the role of p53 in gene expression in the TSG-p53® mouse model. In the study reported here, gene expression levels in tissue derived from the testis, liver, and heart of male, 8-9 week old, p53 wild-type (WT), heterozygous (HET) or knockout (KO) mice were determined utilizing a targeted qPCR 84-gene array. The heart, liver and testis were selected because of the unique function and rate of cell division of each tissue.

Cytogenetic assessment of methylphenidate treatment in pediatric patients treated for attention deficit hyperactivity disorder.

Methylphenidate (MPH, Ritalin), has been prescribed to treat attention deficit/hyperactivity disorder (ADHD) since its approval by the FDA over 50 years ago. Diagnoses of pediatric patients with ADHD and the administration of MPH to treat the symptoms have increased in prevalence in recent years. A 2005 study by El-Zein et al.

The genetic toxicology of methylphenidate hydrochloride in non-human primates.

The studies presented in this work were designed to evaluate the genetic toxicity of methylphenidate hydrochloride (MPH) in non-human primates (NHP) using a long-term, chronic dosing regimen. Thus, approximately two-year old, male rhesus monkeys of Indian origin were orally exposed to MPH diluted in the electrolyte replenisher, Prang, five days per week over a 20-month period. There were 10 animals per dose group and the doses were (1) control, Prang only, (2) low, 0.

Routine diagnostic X-ray examinations and increased frequency of chromosome translocations among U.S. radiologic technologists.

The U.S. population has nearly one radiographic examination per person per year, and concern about cancer risks associated with medical radiation has increased.

Retrospective biodosimetry among United States radiologic technologists.

Measurement of chromosome translocations in peripheral blood lymphocytes has been used to quantify prior exposure to ionizing radiation, including for workers exposed to low, chronic doses. We assessed translocation frequencies in a subset of U.S.