Publications by authors named "Mark J Hoenerhoff"

57 Publications

Multiethnic PDX models predict a possible immune signature associated with TNBC of African ancestry.

Breast Cancer Res Treat 2021 Apr 12;186(2):391-401. Epub 2021 Feb 12.

Department of Internal Medicine, Michigan Medicine, University of Michigan, 1500 East Medical Center Drive, RCC 7314, Ann Arbor, MI, 48105, USA.

Purpose: Triple-negative breast cancer (TNBC) is an aggressive subtype most prevalent among women of Western Sub-Saharan African ancestry. It accounts for 15-25% of African American (AA) breast cancers (BC) and up to 80% of Ghanaian breast cancers, thus contributing to outcome disparities in BC for black women. The aggressive biology of TNBC has been shown to be regulated partially by breast cancer stem cells (BCSC) which mediate tumor recurrence and metastasis and are more abundant in African breast tumors.

Methods: We studied the biological differences between TNBC in women with African ancestry and those of Caucasian women by comparing the gene expression of the BCSC. From low-passage patient derived xenografts (PDX) from Ghanaian (GH), AA, and Caucasian American (CA) TNBCs, we sorted for and sequenced the stem cell populations and analyzed for differential gene enrichment.

Results: In our cohort of TNBC tumors, we observed that the ALDH expressing stem cells display distinct ethnic specific gene expression patterns, with the largest difference existing between the GH and AA ALDH+ cells. Furthermore, the tumors from the women of African ancestry [GH/AA] had ALDH stem cell (SC) enrichment for expression of immune related genes and processes. Among the significantly upregulated genes were CD274 (PD-L1), CXCR9, CXCR10 and IFI27, which could serve as potential drug targets.

Conclusions: Further exploration of the role of immune regulated genes and biological processes in BCSC may offer insight into developing novel approaches to treating TNBC to help ameliorate survival disparities in women with African ancestry.
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http://dx.doi.org/10.1007/s10549-021-06097-8DOI Listing
April 2021

Development of Mast Cell and Eosinophil Hyperplasia and HLH/MAS-Like Disease in NSG-SGM3 Mice Receiving Human CD34+ Hematopoietic Stem Cells or Patient-Derived Leukemia Xenografts.

Vet Pathol 2021 01 19;58(1):181-204. Epub 2020 Nov 19.

5417St. Jude Children's Research Hospital, Memphis, TN, USA.

Immunocompromised mouse strains expressing human transgenes are being increasingly used in biomedical research. The genetic modifications in these mice cause various cellular responses, resulting in histologic features unique to each strain. The NSG-SGM3 mouse strain is similar to the commonly used NSG (NOD gamma) strain but expresses human transgenes encoding stem cell factor (also known as KIT ligand), granulocyte-macrophage colony-stimulating factor, and interleukin 3. This report describes 3 histopathologic features seen in these mice when they are unmanipulated or after transplantation with human CD34+ hematopoietic stem cells (HSCs), virally transduced hCD34+ HSCs, or a leukemia patient-derived xenograft. The first feature is mast cell hyperplasia: unmanipulated, naïve mice develop periductular pancreatic aggregates of murine mast cells, whereas mice given the aforementioned human cells develop a proliferative infiltrative interstitial pancreatic mast cell hyperplasia but with human mast cells. The second feature is the predisposition of NSG-SGM3 mice given these human cells to develop eosinophil hyperplasia. The third feature, secondary hemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS)-like disease, is the most pronounced in both its clinical and histopathologic presentations. As part of this disease, a small number of mice also have histiocytic infiltration of the brain and spinal cord with subsequent neurologic or vestibular signs. The presence of any of these features can confound accurate histopathologic interpretation; therefore, it is important to recognize them as strain characteristics and to differentiate them from what may be experimentally induced in the model being studied.
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http://dx.doi.org/10.1177/0300985820970144DOI Listing
January 2021

Protons and High-Linear Energy Transfer Radiation Induce Genetically Similar Lymphomas With High Penetrance in a Mouse Model of the Aging Human Hematopoietic System.

Int J Radiat Oncol Biol Phys 2020 11 4;108(4):1091-1102. Epub 2020 Jul 4.

Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida; Department of Radiation Oncology, University of Miami, Miami, Florida. Electronic address:

Purpose: Humans are exposed to charged particles in different scenarios. The use of protons and high-linear energy transfer (LET) in cancer treatment is steadily growing. In outer space, astronauts will be exposed to a mixed radiation field composed of both protons and heavy ions, in particularly the long-term space missions outside of earth's magnetosphere. Thus, understanding the radiobiology and transforming potential of these types of ionizing radiation are of paramount importance.

Methods And Materials: We examined the effect of 10 or 100 cGy of whole-body doses of protons or Si ions on the hematopoietic system of a genetic model of aging based on recent studies that showed selective loss of the MLH1 protein in human hematopoietic stems with age.

Results: We found that Mlh1 deficient animals are highly prone to develop lymphomas when exposed to either low doses of protons or Si ions. The lymphomas that develop are genetically indistinguishable, in spite of different types of damage elicited by low- and high-LET radiation. RNA sequencing analyses reveal similar gene expression patterns, similar numbers of altered genes, similar numbers of single nucleotide variants and insertions and deletions, and similar activation of known leukemogenic loci.

Conclusions: Although the incidence of malignancy is related to radiation quality, and increased due to loss of Mlh1, the phenotype of the tumors is independent of LET.
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http://dx.doi.org/10.1016/j.ijrobp.2020.06.070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7572653PMC
November 2020

Unique microRNA alterations in hepatocellular carcinomas arising either spontaneously or due to chronic exposure to Ginkgo biloba extract (GBE) in B6C3F1/N mice.

Arch Toxicol 2020 07 18;94(7):2523-2541. Epub 2020 Apr 18.

Cellular and Molecular Pathology Branch, DNTP, NIEHS, Research Triangle Park, NC, 27709, USA.

Ginkgo biloba extract (GBE) is used in traditional Chinese medicine as a herbal supplement for improving memory. Exposure of B6C3F1/N mice to GBE in a 2-year National Toxicology Program (NTP) bioassay resulted in a dose-dependent increase in hepatocellular carcinomas (HCC). To identify key microRNAs that modulate GBE-induced hepatocarcinogenesis, we compared the global miRNA expression profiles in GBE-exposed HCC (GBE-HCC) and spontaneous HCC (SPNT-HCC) with age-matched vehicle control normal livers (CNTL) from B6C3F1/N mice. The number of differentially altered miRNAs in GBE-HCC and SPNT-HCC was 74 (52 up and 22 down) and 33 (15 up and 18 down), respectively. Among the uniquely differentially altered miRNAs in GBE-HCC, miR-31 and one of its predicted targets, Cdk1 were selected for functional validation. A potential miRNA response element (MRE) in the 3'-untranslated regions (3'-UTR) of Cdk1 mRNA was revealed by in silico analysis and confirmed by luciferase assays. In mouse hepatoma cell line HEPA-1 cells, we demonstrated an inverse correlation between miR-31 and CDK1 protein levels, but no change in Cdk1 mRNA levels, suggesting a post-transcriptional effect. Additionally, a set of miRNAs (miRs-411, 300, 127, 134, 409-3p, and 433-3p) that were altered in the GBE-HCCs were also altered in non-tumor liver samples from the 90-day GBE-exposed group compared to the vehicle control group, suggesting that some of these miRNAs could serve as potential biomarkers for GBE exposure or hepatocellular carcinogenesis. These data increase our understanding of miRNA-mediated epigenetic regulation of GBE-mediated hepatocellular carcinogenesis in B6C3F1/N mice.
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http://dx.doi.org/10.1007/s00204-020-02749-8DOI Listing
July 2020

Effects of Trio and Pair Breeding of Mice on Environmental Parameters and Nasal Pathology and Their Implications for Cage Change Frequency.

J Am Assoc Lab Anim Sci 2020 05 28;59(3):288-297. Epub 2020 Feb 28.

Refinement and Enrichment Advancements Laboratory (REAL), University of Michigan, Ann Arbor, Michigan;, Email:

According to the , cage change frequencies must be considered when cage density requirements are exceeded. We monitored ammonia, carbon dioxide, cage wetness, health status, and breeding parameters of trio and pair breeding cages containing CD1 mice in ventilated and static microisolation caging (4 cages per condition) daily for approximately 6 wk. Minimum cage change frequencies for each condition were determined on the basis of performance data. At 3 d after cage change, static trio and pair cages had average ammonia levels of 74 and 38 ppm. Ventilated cages remained below the 25ppm threshold reported to be potentially deleterious for mice until at least day 7 after cage change. By 7 d after cage change, ammonia levels had risen to an average of 100 ppm and 64 ppm in static trio and pair cages and to 34 ppm and 20 ppm in ventilated trio and pair cages, respectively. Ammonia levels in ventilated cages continued to rise slowly through day 14 after cage change. CO₂ levels exceeded 5000 ppm in all groups at 2 d after cage change. Pair breeders in ventilated cages took the longest-10 to 14 d-to reach cage wetness threshold scores. On day 7, pups in trio static cages were noted to have decreased and squinted eyes, whereas in ventilated cages containing trios and pairs, these clinical signs were rare to absent. Histologically, there was an increasing incidence and severity of nasal lesions in weanlings with increasing housing density and decreasing ventilation, consistent with nasal epithelial toxicity. Given these parameters, we concluded that under the current husbandry conditions, it may be necessary to change breeders in static cages more frequently than every 7 d. Additional studies are necessary to evaluate the effects of more frequent cage changes on reproductive parameters, given that cage changing is stressful for mice and affects breeding results.
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http://dx.doi.org/10.30802/AALAS-JAALAS-19-000074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7210739PMC
May 2020

Histology Atlas of the Developing Mouse Urinary System With Emphasis on Prenatal Days E10.5-E18.5.

Toxicol Pathol 2019 10 10;47(7):865-886. Epub 2019 Oct 10.

Experimental Pathology Laboratories, Inc, Research Triangle Park, NC, USA.

Congenital abnormalities of the urinary tract are some of the most common human developmental abnormalities. Several genetically engineered mouse models have been developed to mimic these abnormalities and aim to better understand the molecular mechanisms of disease. This atlas has been developed as an aid to pathologists and other biomedical scientists for identification of abnormalities in the developing murine urinary tract by cataloguing normal structures at each stage of development. Hematoxylin and eosin- and immunohistochemical-stained sections are provided, with a focus on E10.5-E18.5, as well as a brief discussion of postnatal events in urinary tract development. A section on abnormalities in the development of the urinary tract is also provided, and molecular mechanisms are presented as supplementary material. Additionally, overviews of the 2 key processes of kidney development, branching morphogenesis and nephrogenesis, are provided to aid in the understanding of the complex organogenesis of the kidney. One of the key findings of this atlas is the histological identification of the ureteric bud at E10.5, as previous literature has provided conflicting reports on the initial point of budding. Furthermore, attention is paid to points where murine development is significantly distinct from human development, namely, in the cessation of nephrogenesis.
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http://dx.doi.org/10.1177/0192623319873871DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6814567PMC
October 2019

Genome-wide promoter DNA methylation profiling of hepatocellular carcinomas arising either spontaneously or due to chronic exposure to Ginkgo biloba extract (GBE) in B6C3F1/N mice.

Arch Toxicol 2019 08 5;93(8):2219-2235. Epub 2019 Jul 5.

Cellular and Molecular Pathology Branch, Division of National Toxicology Program (DNTP), National Institute of Environmental Health Sciences (NIEHS), 111 T.W. Alexander Drive, Research Triangle Park, NC, 27709, USA.

Epigenetic modifications, such as DNA methylation, play an important role in carcinogenesis. In a recent NTP study, chronic exposure of B6C3F1/N mice to Ginkgo biloba extract (GBE) resulted in a high incidence of hepatocellular carcinomas (HCC). Genome-wide promoter methylation profiling on GBE-exposed HCC (2000 mg/kg group), spontaneous HCC (vehicle-control group), and age-matched vehicle control liver was performed to identify differentially methylated genes in GBE-exposed HCC and spontaneous HCC. DNA methylation alterations were correlated to the corresponding global gene expression changes. Compared to control liver, 1296 gene promoters (719 hypermethylated, 577 hypomethylated) in GBE-exposed HCC and 738 (427 hypermethylated, 311 hypomethylated) gene promoters in spontaneous HCC were significantly differentially methylated, suggesting an impact of methylation on GBE-exposed HCC. Differential methylation of promoter regions in relevant cancer genes (cMyc, Spry2, Dusp5) and their corresponding differential gene expression was validated by quantitative pyrosequencing and qRT-PCR, respectively. In conclusion, we have identified differentially methylated promoter regions of relevant cancer genes altered in GBE-exposed HCC compared to spontaneous HCC. Further study of unique sets of differentially methylated genes in chemical-exposed mouse HCC could potentially be used to differentiate treatment-related tumors from spontaneous-tumors in cancer bioassays and provide additional understanding of the underlying epigenetic mechanisms of chemical carcinogenesis.
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http://dx.doi.org/10.1007/s00204-019-02505-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6830449PMC
August 2019

Long-term Effects of Hypothermic Ex Situ Perfusion on Skeletal Muscle Metabolism, Structure, and Force Generation After Transplantation.

Transplantation 2019 10;103(10):2105-2112

Department of Orthopaedic Surgery, University of Michigan Health System, Ann Arbor, MI.

Background: Hypothermic ex situ perfusion (HESP) systems are used to prolong allograft survival in solid organ transplantations and have been shown to be superior to static cold storage (SCS) methods. However, the effect of this preservation method on limb allograft survival and long-term function has not yet been tested. In this study, we investigated the long-term effects of the HESP on skeletal muscle metabolism, structure, and force generation and compared it with the current standard of preservation.

Methods: Forty male Lewis rats (250 ± 25 g) were divided into 5 groups, including naive control, sciatic nerve transection or repair, immediate transplantation, SCS, and HESP. For the SCS group, limbs were preserved at 4°C for 6 hours. In the HESP group, limbs were continuously perfused with oxygenated histidine-tryptophan-ketoglutarate (HTK) solution at 10-15°C for 6 hours. Hemodynamic and biochemical parameters of perfusion were recorded throughout the experiment. At 12 weeks, electromyography and muscle force measurements (maximum twitch and tetanic forces) were obtained along with muscle samples for histology and metabolomics analysis.

Results: Histology demonstrated 48% myocyte injury in the HESP group compared with 49% in immediate transplantation (P = 0.96) and 74% in the SCS groups (P < 0.05). The maximum twitch force measurement revealed a significantly higher force in the HESP group compared with the SCS group (P = 0.029). Essential amino acid levels of the gastrocnemius muscle did not reach significance, with the exception of higher proline levels in the HESP group.

Conclusions: HESP using HTK protects viability of the limb but fails to restore muscle force in the long term.
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http://dx.doi.org/10.1097/TP.0000000000002800DOI Listing
October 2019

Inflammasome activation is required for human rhinovirus-induced airway inflammation in naive and allergen-sensitized mice.

Mucosal Immunol 2019 07 15;12(4):958-968. Epub 2019 May 15.

Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.

Activation of the inflammasome is a key function of the innate immune response that regulates inflammation in response to microbial substances. Inflammasome activation by human rhinovirus (RV), a major cause of asthma exacerbations, has not been well studied. We examined whether RV induces inflammasome activation in vivo, molecular mechanisms underlying RV-stimulated inflammasome priming and activation, and the contribution of inflammasome activation to RV-induced airway inflammation and exacerbation. RV infection triggered lung mRNA and protein expression of pro-IL-1β and NLRP3, indicative of inflammasome priming, as well as cleavage of caspase-1 and pro-IL-1β, completing inflammasome activation. Immunofluorescence staining showed IL-1β in lung macrophages. Depletion with clodronate liposomes and adoptive transfer experiments showed macrophages to be required and sufficient for RV-induced inflammasome activation. TLR2 was required for RV-induced inflammasome priming in vivo. UV irradiation blocked inflammasome activation and RV genome was sufficient for inflammasome activation in primed cells. Naive and house dust mite-treated NLRP3-/- and IL-1β-/- mice, as well as IL-1 receptor antagonist-treated mice, showed attenuated airway inflammation and responsiveness following RV infection. We conclude that RV-induced inflammasome activation is required for maximal airway inflammation and hyperresponsiveness in naive and allergic mice. The inflammasome represents a molecular target for RV-induced asthma exacerbations.
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http://dx.doi.org/10.1038/s41385-019-0172-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6668626PMC
July 2019

Do GISTs Occur in Rats and Mice? Immunohistochemical Characterization of Gastrointestinal Tumors Diagnosed as Smooth Muscle Tumors in The National Toxicology Program.

Toxicol Pathol 2019 07 7;47(5):577-584. Epub 2019 May 7.

2 Division of National Toxicology Program, Cellular and Molecular Pathology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA. Venkannagari is now with the Bain and Company Inc, Boston, MA, USA. Mark is now with the Unit for Laboratory Animal Medicine, University of Michigan, Ann Arbor, MI, USA.

The majority of the tumors in the gastrointestinal (GI) tract of rats and mice, with spindle cell morphology, are diagnosed as smooth muscle tumors (SMTs). Similarly, several decades ago human GI tumors with spindle cell morphology were also diagnosed as SMTs. However, later investigations identified most of these tumors in humans as gastrointestinal stromal tumors (GISTs). The GISTs are considered to arise from the interstitial cells of Cajal located throughout the GI tract. Positive immunohistochemical staining with CKIT antibody is a well-accepted diagnostic marker for GISTs in humans. Since there is a considerable overlap between the histomorphology of SMTs and GISTs, it is not possible to distinguish them on hematoxylin and eosin stained sections. As a result, GISTs are not routinely diagnosed in toxicological studies. The current study was designed to evaluate the tumors diagnosed as leiomyoma or leiomyosarcoma in the National Toxicology Program's 2-year bioassays using CKIT, smooth muscle actin, and desmin immunohistochemistry. The results demonstrate that most of the mouse SMTs diagnosed as leiomyoma or leiomyosarcoma are likely GISTs, whereas in rats the tumors are likely SMTs and not GISTs.
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http://dx.doi.org/10.1177/0192623319845838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7836069PMC
July 2019

The Endothelin-A Receptor Antagonist Zibotentan Induces Damage to the Nasal Olfactory Epithelium Possibly Mediated in Part through Type 2 Innate Lymphoid Cells.

Toxicol Pathol 2019 02 30;47(2):150-164. Epub 2018 Dec 30.

1 Unit for Laboratory Animal Medicine, University of Michigan, Ann Arbor, Michigan, USA.

Zibotentan, an endothelin-A receptor antagonist, has been used in the treatment of various cardiovascular disorders and neoplasia. Castrated athymic nude mice receiving zibotentan for a preclinical xenograft efficacy study experienced weight loss, gastrointestinal bloat, and the presence of an audible respiratory click. Human side effects have been reported in the nasal cavity, so we hypothesized that the nasal cavity is a target for toxicity in mice receiving zibotentan. Lesions in the nasal cavity predominantly targeted olfactory epithelium in treated mice and were more pronounced in castrated animals. Minimal lesions were present in vehicle control animals, which suggested possible gavage-related reflux injury. The incidence, distribution, and morphology of lesions suggested direct exposure to the nasal mucosa and a possible systemic effect targeting the olfactory epithelium, driven by a type 2 immune response, with group 2 innate lymphoid cell involvement. Severe nasal lesions may have resulted in recurrent upper airway obstruction, leading to aerophagia and associated clinical morbidity. These data show the nasal cavity is a target of zibotentan when given by gavage in athymic nude mice, and such unanticipated and off-target effects could impact interpretation of research results and animal health in preclinical studies.
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http://dx.doi.org/10.1177/0192623318816295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7357205PMC
February 2019

Digital Microscopy, Image Analysis, and Virtual Slide Repository.

ILAR J 2018 12;59(1):66-79

Famke Aeffner, DVM PhD DACVP, is a principal pathologist in the Comparative Biology and Safety Sciences Department at Amgen Inc. in South San Francisco, California. Hibret Adissu, DVM PhD DVSc DACVP, is an investigative pathologist in the Laboratory of Cancer Biology and Genetics, Center for Cancer Research, at the National Cancer Institute in Bethesda, Maryland. Michael C. Boyle, DVM PhD DACVP DABT, is a principal pathologist in the Comparative Biology and Safety Sciences at Amgen Inc. in Thousand Oaks, California. Robert D. Cardiff, MD PhD, is a distinguished professor of pathology (emeritus) at the Center for Comparative Medicine at the University of California in Davis, California. Erik Hagendorn is a senior scientist of informatics at AbbVie Bioresearch in Worcester, Massachusetts. Mark J. Hoenerhoff, DVM PhD DACVP, is an associate professor and veterinary pathologist at the In Vivo Animal Core, Unit for Laboratory Animal Medicine, at the University of Michigan in Ann Arbor, Michigan. Robert Klopfleisch, DVM PhD DACVP, is an associate professor at the Institute of Veterinary Pathology of the Freie Universitaet Berlin, in Berlin, Germany. Susan Newbigging, BSc MSc DVM DVSc, is a pathologist and Director of The Pathology Core at the Toronto Center of Phenogenomics in Toronto, Ontario, Canada. Dirk Schaudien, DVM PhD DACVP, is a veterinary pathologist at the Fraunhofer Institute for Toxicology and Experimental Medicine, in Hannover, Germany. Oliver Turner, BSC(Hons), BVSc MRCVS PhD DACVP DABT, is a senior pathologist in the Preclinical Safety department of Novartis Pharmaceuticals in East Hanover, New Jersey. Kristin Wilson, DVM PhD DACVP, is a pathologist at Flagship Biosciences Inc. in Westminster, Colorado.

Advancements in technology and digitization have ushered in novel ways of enhancing tissue-based research via digital microscopy and image analysis. Whole slide imaging scanners enable digitization of histology slides to be stored in virtual slide repositories and to be viewed via computers instead of microscopes. Easier and faster sharing of histologic images for teaching and consultation, improved storage and preservation of quality of stained slides, and annotation of features of interest in the digital slides are just a few of the advantages of this technology. Combined with the development of software for digital image analysis, digital slides further pave the way for the development of tools that extract quantitative data from tissue-based studies. This review introduces digital microscopy and pathology, and addresses technical and scientific considerations in slide scanning, quantitative image analysis, and slide repositories. It also highlights the current state of the technology and factors that need to be taken into account to insure optimal utility, including preanalytical considerations and the importance of involving a pathologist in all major steps along the digital microscopy and pathology workflow.
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http://dx.doi.org/10.1093/ilar/ily007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6927898PMC
December 2018

Nitric oxide-releasing semi-crystalline thermoplastic polymers: preparation, characterization and application to devise anti-inflammatory and bactericidal implants.

Biomater Sci 2018 Nov;6(12):3189-3201

Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.

Semi-crystalline thermoplastics are an important class of biomaterials with applications in creating extracorporeal and implantable medical devices. In situ release of nitric oxide (NO) from medical devices can enhance their performance via NO's potent anti-thrombotic, bactericidal, anti-inflammatory, and angiogenic activity. However, NO-releasing semi-crystalline thermoplastic systems are limited and the relationship between polymer crystallinity and NO release profile is unknown. In this paper, the functionalization of poly(ether-block-amide) (PEBA), Nylon 12, and polyurethane tubes, as examples of semi-crystalline polymers, with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) within, is demonstrated via a polymer swelling method. The degree of crystallinity of the polymer plays a crucial role in both SNAP impregnation and NO release. Nylon 12, which has a relatively high degree of crystallinity, exhibits an unprecedented NO release duration of over 5 months at a low NO level, while PEBA tubing exhibits NO release over days to weeks. As a new biomedical application of NO, the NO-releasing PEBA tubing is examined as a cannula for continuous subcutaneous insulin infusion. The released NO is shown to enhance insulin absorption into the bloodstream probably by suppressing the tissue inflammatory response, and thereby could benefit insulin pump therapy for diabetes management.
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http://dx.doi.org/10.1039/c8bm00849cDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6246781PMC
November 2018

Mlh1 deficiency increases the risk of hematopoietic malignancy after simulated space radiation exposure.

Leukemia 2019 05 1;33(5):1135-1147. Epub 2018 Oct 1.

Sylvester Comprehensive Cancer Center, University of Miami, Miami, FL, USA.

Cancer-causing genome instability is a major concern during space travel due to exposure of astronauts to potent sources of high-linear energy transfer (LET) ionizing radiation. Hematopoietic stem cells (HSCs) are particularly susceptible to genotoxic stress, and accumulation of damage can lead to HSC dysfunction and oncogenesis. Our group recently demonstrated that aging human HSCs accumulate microsatellite instability coincident with loss of MLH1, a DNA Mismatch Repair (MMR) protein, which could reasonably predispose to radiation-induced HSC malignancies. Therefore, in an effort to reduce risk uncertainty for cancer development during deep space travel, we employed an Mlh1 mouse model to study the effects high-LET Fe ion space-like radiation. Irradiated Mlh1 mice showed a significantly higher incidence of lymphomagenesis with Fe ions compared to γ-rays and unirradiated mice, and malignancy correlated with increased MSI in the tumors. In addition, whole-exome sequencing analysis revealed high SNVs and INDELs in lymphomas being driven by loss of Mlh1 and frequently mutated genes had a strong correlation with human leukemias. Therefore, the data suggest that age-related MMR deficiencies could lead to HSC malignancies after space radiation, and that countermeasure strategies will be required to adequately protect the astronaut population on the journey to Mars.
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http://dx.doi.org/10.1038/s41375-018-0269-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6443507PMC
May 2019

Nonproliferative and Proliferative Lesions of the Rat and Mouse Endocrine System.

J Toxicol Pathol 2018 28;31(3 Suppl):1S-95S. Epub 2018 Jul 28.

Ohio University, Department of Biomedical Sciences, Athens, Ohio, USA.

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) Project (www.toxpath.org/inhand.asp) is a joint initiative among the Societies of Toxicological Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in the endocrine organs (pituitary gland, pineal gland, thyroid gland, parathyroid glands, adrenal glands and pancreatic islets) of laboratory rats and mice, with color photomicrographs illustrating examples of the lesions. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for endocrine lesions in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.
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http://dx.doi.org/10.1293/tox.31.1SDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6108091PMC
July 2018

Functions of the COPII gene paralogs SEC23A and SEC23B are interchangeable in vivo.

Proc Natl Acad Sci U S A 2018 08 31;115(33):E7748-E7757. Epub 2018 Jul 31.

Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109;

Approximately one-third of the mammalian proteome is transported from the endoplasmic reticulum-to-Golgi via COPII-coated vesicles. SEC23, a core component of coat protein-complex II (COPII), is encoded by two paralogous genes in vertebrates ( and ). In humans, SEC23B deficiency results in congenital dyserythropoietic anemia type-II (CDAII), while SEC23A deficiency results in a skeletal phenotype (with normal red blood cells). These distinct clinical disorders, together with previous biochemical studies, suggest unique functions for SEC23A and SEC23B. Here we show indistinguishable intracellular protein interactomes for human SEC23A and SEC23B, complementation of yeast Sec23 by both human and murine SEC23A/B, and rescue of the lethality of deficiency in zebrafish by a -expressing transgene. We next demonstrate that a coding sequence inserted into the murine locus completely rescues the lethal SEC23B-deficient pancreatic phenotype. We show that SEC23B is the predominantly expressed paralog in human bone marrow, but not in the mouse, with the reciprocal pattern observed in the pancreas. Taken together, these data demonstrate an equivalent function for SEC23A/B, with evolutionary shifts in the transcription program likely accounting for the distinct phenotypes of SEC23A/B deficiency within and across species, a paradigm potentially applicable to other sets of paralogous genes. These findings also suggest that enhanced erythroid expression of the normal gene could offer an effective therapeutic approach for CDAII patients.
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http://dx.doi.org/10.1073/pnas.1805784115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6099849PMC
August 2018

Exome Sequencing of Fresh-frozen or Formalin-fixed Paraffin-embedded B6C3F1/N Mouse Hepatocellular Carcinomas Arising Either Spontaneously or due to Chronic Chemical Exposure.

Toxicol Pathol 2018 08 25;46(6):706-718. Epub 2018 Jul 25.

1 Division of the National Toxicology Program, NIEHS, Research Triangle Park, North Carolina, USA.

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide; however, the mutational properties of HCC-associated carcinogens remain largely uncharacterized. We hypothesized that mechanisms underlying chemical-induced HCC can be characterized by evaluating the mutational spectra of these tumors. To test this hypothesis, we performed exome sequencing of B6C3F1/N HCCs that arose either spontaneously in vehicle controls ( n = 3) or due to chronic exposure to gingko biloba extract (GBE; n = 4) or methyleugenol (MEG; n = 3). Most archived tumor samples are available as formalin-fixed paraffin-embedded (FFPE) blocks, rather than fresh-frozen (FF) samples; hence, exome sequencing from paired FF and FFPE samples was compared. FF and FFPE samples showed 63% to 70% mutation concordance. Multiple known (e.g., Ctnnb1T41A, BrafV637E) and novel (e.g., Erbb4C559S, Card10A700V, and Klf11P358L) mutations in cancer-related genes were identified. The overall mutational burden was greater for MEG than for GBE or spontaneous HCC samples. To characterize the mutagenic mechanisms, we analyzed the mutational spectra in the HCCs according to their trinucleotide motifs. The MEG tumors clustered closest to Catalogue of Somatic Mutations in Cancer signatures 4 and 24, which are, respectively, associated with benzo(a)pyrene- and aflatoxin-induced HCCs in humans. These results establish a novel approach for classifying liver carcinogens and understanding the mechanisms of hepatocellular carcinogenesis.
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http://dx.doi.org/10.1177/0192623318789398DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6117200PMC
August 2018

Utilization of Ultrasound Guided Tissue-directed Cellular Implantation for the Establishment of Biologically Relevant Metastatic Tumor Xenografts.

J Vis Exp 2018 05 25(135). Epub 2018 May 25.

Departments of Surgery, C.S Mott Children's and Women's Hospital, The University of Michigan Medical School;

Preclinical testing of anticancer therapies relies on relevant xenograft models that mimic the innate tendencies of cancer. Advantages of standard subcutaneous flank models include procedural ease and the ability to monitor tumor progression and response without invasive imaging. Such models are often inconsistent in translational clinical trials and have limited biologically relevant characteristics with low proclivity to produce metastasis, as there is a lack of a native microenvironment. In comparison, orthotopic xenograft models at native tumor sites have been shown to mimic the tumor microenvironment and replicate important disease characteristics such as distant metastatic spread. These models often require tedious surgical procedures with prolonged anesthetic time and recovery periods. To address this, cancer researchers have recently utilized ultrasound-guided injection techniques to establish cancer xenograft models for preclinical experiments, which allows for rapid and reliable establishment of tissue-directed murine models. Ultrasound visualization also provides a noninvasive method for longitudinal assessment of tumor engraftment and growth. Here, we describe the method for ultrasound-guided injection of cancer cells, utilizing the adrenal gland for NB and renal sub capsule for ES. This minimally invasive approach overcomes tedious open surgery implantation of cancer cells in tissue-specific locations for growth and metastasis, and abates morbid recovery periods. We describe the utilization of both established cell lines and patient derived cell lines for orthotopic injection. Pre-made commercial kits are available for tumor dissociation and luciferase tagging of cells. Injection of cell suspension using image-guidance provides a minimally invasive and reproducible platform for the creation of preclinical models. This method is utilized to create reliable preclinical models for other cancers such as bladder, liver and pancreas exemplifying its untapped potential for numerous cancer models.
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http://dx.doi.org/10.3791/57558DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6101425PMC
May 2018

Reduced Disc Shedding and Phagocytosis of Photoreceptor Outer Segment Contributes to Kava Kava Extract-induced Retinal Degeneration in F344/N Rats.

Toxicol Pathol 2018 07 27;46(5):564-573. Epub 2018 May 27.

1 National Toxicology Program, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, North Carolina, USA.

There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava kava extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essential to maintain the homeostasis of the photoreceptor layer and is regulated by melatonin signaling. Therefore, reduced photoreceptor outer segment disc shedding and subsequent lower number of phagosomes in the RPE and alterations in the melatonin pathway may have contributed to the increased incidences of retinal degeneration observed in F344/N rats in the 2-year KKE bioassay.
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http://dx.doi.org/10.1177/0192623318778796DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6027611PMC
July 2018

Bacterial and Infections in the Lungs of Gene-Knockout Rabbits with Severe Combined Immunodeficiency.

Front Immunol 2018 9;9:429. Epub 2018 Mar 9.

Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical Center, University of Michigan Medical School, Ann Arbor, MI, United States.

Using the CRISPR/Cas9 gene-editing technology, we recently produced a number of rabbits with mutations in immune function genes, including FOXN1, PRKDC, RAG1, RAG2, and IL2RG. Seven founder knockout rabbits (F0) and three male IL2RG null (-/y) F1 animals demonstrated severe combined immunodeficiency (SCID), characterized by absence or pronounced hypoplasia of the thymus and splenic white pulp, and absence of immature and mature T and B-lymphocytes in peripheral blood. Complete blood count analysis showed severe leukopenia and lymphocytopenia accompanied by severe neutrophilia. Without prophylactic antibiotics, the SCID rabbits universally succumbed to lung infections following weaning. Pathology examination revealed severe heterophilic bronchopneumonia caused by in several animals, but a consistent feature of lung lesions in all animals was a severe interstitial pneumonia caused by , as confirmed by histological examination and PCR analysis of genes. The results of this study suggest that these SCID rabbits could serve as a useful model for human SCID to investigate the disease pathogenesis and the development of gene and drug therapies.
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http://dx.doi.org/10.3389/fimmu.2018.00429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5854650PMC
June 2019

Obesity and High-Fat Diet Induce Distinct Changes in Placental Gene Expression and Pregnancy Outcome.

Endocrinology 2018 04;159(4):1718-1733

Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan.

Obese women are at high risk of pregnancy complications, including preeclampsia, miscarriage, preterm birth, stillbirth, and neonatal death. In the current study, we aimed to determine the effects of obesity on pregnancy outcome and placental gene expression in preclinical mouse models of genetic and nutritional obesity. The leptin receptor (LepR) null-reactivatable (LepRloxTB), LepR-deficient (Leprdb/+), and high-fat diet (HFD)-fed mice were assessed for fertility, pregnancy outcome, placental morphology, and placental transcriptome using standard quantitative polymerase chain reaction (qPCR) and qPCR arrays. The restoration of fertility of LepRloxTB was performed by stereotaxic delivery of adeno-associated virus-Cre into the hypothalamic ventral premammillary nucleus. Fertile LepRloxTB females were morbidly obese, whereas the wild-type mice-fed HFD showed only a mild increase in body weight. Approximately 80% of the LepRloxTB females had embryo resorptions (∼40% of the embryos). In HFD mice, the number of resorptions was not different from controls fed a regular diet. Placentas of resorbed embryos from obese mice displayed necrosis and inflammatory infiltrate in the labyrinth and changes in the expression of genes associated with angiogenesis and inflammation (e.g., Vegfa, Hif1a, Nfkbia, Tlr3, Tlr4). In contrast, placentas from embryos of females on HFD showed changes in a different set of genes, mostly associated with cellular growth and response to stress (e.g., Plg, Ang, Igf1, Igfbp1, Fgf2, Tgfb2, Serpinf1). Sexual dimorphism in gene expression was only apparent in placentas from obese LepRloxTB mice. Our findings indicate that an obese environment and HFD have distinct effects on pregnancy outcome and the placental transcriptome.
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http://dx.doi.org/10.1210/en.2017-03053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6456933PMC
April 2018

Alternative NHEJ pathway proteins as components of MYCN oncogenic activity in human neural crest stem cell differentiation: implications for neuroblastoma initiation.

Cell Death Dis 2017 12 13;8(12):3208. Epub 2017 Dec 13.

Department of Pediatrics, C.S. Mott Children and Women's Hospital, The University of Michigan Medical School, Ann Arbor, MI, USA.

Neuroblastoma is a cancer of neural crest stem cell (NCSC) lineage. Signaling pathways that regulate NCSC differentiation have been implicated in neuroblastoma tumorigenesis. This is exemplified by MYCN oncogene targets that balance proliferation, differentiation, and cell death similarly in normal NCSC and in high-risk neuroblastoma. Our previous work discovered a survival mechanism by which MYCN-amplified neuroblastoma circumvents cell death by upregulating components of the error-prone non-canonical alternative nonhomologous end-joining (alt-NHEJ) DNA repair pathway. Similar to proliferating stem cells, high-risk neuroblastoma cells have enhanced DNA repair capacity, overcoming DNA damage with higher repair efficiency than somatic cells. Adequate DNA maintenance is required for lineage protection as stem cells proliferate and during tumor progression to overcome oncogene-induced replication stress. On this basis, we hypothesized that alt-NHEJ overexpression in neuroblastoma is a cancer cell survival mechanism that originates from DNA repair systems of NCSC, the presumed progenitor cell of origin. A human NCSC model was generated in which inducible MYCN triggered an immortalized phenotype capable of forming metastatic neuroectodermal tumors in mice, resembling human neuroblastoma. Critical alt-NHEJ components (DNA Ligase III, DNA Ligase I, and Poly [ADP-ribose polymerase 1]) were highly expressed in normal early NCSC, and decreased as cells became terminally differentiated. Constitutive MYCN expression maintained high alt-NHEJ protein expression, preserving the expression pattern of the immature neural phenotype. siRNA knockdown of alt-NHEJ components reversed MYCN effects on NCSC proliferation, invasion, and migration. DNA Ligase III, Ligase I, and PARP1 silencing significantly decreased neuroblastoma markers expression (TH, Phox2b, and TRKB). These results utilized the first human NCSC model of neuroblastoma to uncover an important link between MYCN and alt-NHEJ expression in developmental tumor initiation, setting precedence to investigate alt-NHEJ repair mechanics in neuroblastoma DNA maintenance.
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http://dx.doi.org/10.1038/s41419-017-0004-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5870584PMC
December 2017

Neutrophil-Particle Interactions in Blood Circulation Drive Particle Clearance and Alter Neutrophil Responses in Acute Inflammation.

ACS Nano 2017 11 19;11(11):10797-10807. Epub 2017 Oct 19.

Department of Chemical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States.

Although nano- and microparticle therapeutics have been studied for a range of drug delivery applications, the presence of these particles in blood flow may have considerable and understudied consequences to circulating leukocytes, especially neutrophils, which are the largest human leukocyte population. The objective of this work was to establish if particulate drug carriers in circulation interfere with normal neutrophil adhesion and migration. Circulating blood neutrophils in vivo were found to be capable of rapidly binding and sequestering injected carboxylate-modified particles of both 2 and 0.5 μm diameter within the bloodstream. These neutrophil-particle associations within the vasculature were found to suppress neutrophil interactions with an inflamed mesentery vascular wall and hindered neutrophil adhesion. Furthermore, in a model of acute lung injury, intravenously administered drug-free particles reduced normal neutrophil accumulation in the airways of C57BL/6 mice between 52% and 60% versus particle-free mice and between 93% and 98% in BALB/c mice. This suppressed neutrophil migration resulted from particle-induced neutrophil diversion to the liver. These data indicate a considerable acute interaction between injected particles and circulating neutrophils that can drive variations in neutrophil function during inflammation and implicate neutrophil involvement in the clearance process of intravenously injected particle therapeutics. Such an understanding will be critical toward both enhancing designs of drug delivery carriers and developing effective therapeutic interventions in diseases where neutrophils have been implicated.
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http://dx.doi.org/10.1021/acsnano.7b03190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5709153PMC
November 2017

Tissue-directed Implantation Using Ultrasound Visualization for Development of Biologically Relevant Metastatic Tumor Xenografts.

In Vivo 2017 Sep-Oct;31(5):779-791

Department of Surgery, C.S Mott Children's and Women's Hospital, Mott Solid Tumor Oncology Program, The University of Michigan Medical School, Ann Arbor, MI, U.S.A.

Background: Advances in cancer therapeutics depend on reliable in vivo model systems. To develop biologically relevant xenografts, ultrasound was utilized for tissue-directed implantation of neuroblastoma (NB) cell line and patient-derived tumors in the adrenal gland, and for renal subcapsular engraftment of Ewing's sarcoma (ES).

Materials And Methods: NB xenografts were established by direct adrenal injection of luciferase-transfected NB cell lines (IMR32, SH-SY5Y, SK-N-BE2) or NB patient-derived tumor cells (UMNBL001, UMNBL002). ES xenografts were established by renal subcapsular injection of TC32, A673, CHLA-25, or A4573 cells. Progression was monitored by in vivo imaging.

Results: Tumors progressed to local disease with metastasis evident by 5 weeks. Metastatic sites included cortical bone, lung, liver, and lymph nodes. Xenografted tumors retained immunochemical features of the original cancer.

Conclusion: Human NB adrenal xenografts, including two patient-derived orthotopic, and ES renal subcapsular xenografts were established by ultrasound without open surgery. Tissue-directed implantation is an effective technique for developing metastatic preclinical models.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5656850PMC
http://dx.doi.org/10.21873/invivo.11131DOI Listing
May 2018

SEC23B is required for pancreatic acinar cell function in adult mice.

Mol Biol Cell 2017 Jul 24;28(15):2146-2154. Epub 2017 May 24.

Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109

Mice with germline absence of SEC23B die perinatally, exhibiting massive pancreatic degeneration. We generated mice with tamoxifen-inducible, pancreatic acinar cell-specific deletion. Inactivation of exclusively in the pancreatic acinar cells of adult mice results in decreased overall pancreatic weights from pancreatic cell loss (decreased pancreatic DNA, RNA, and total protein content), as well as degeneration of exocrine cells, decreased zymogen granules, and alterations in the endoplasmic reticulum (ER), ranging from vesicular ER to markedly expanded cisternae with accumulation of moderate-density content or intracisternal granules. Acinar deletion results in induction of ER stress and increased apoptosis in the pancreas, potentially explaining the loss of pancreatic cells and decreased pancreatic weight. These findings demonstrate that SEC23B is required for normal function of pancreatic acinar cells in adult mice.
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http://dx.doi.org/10.1091/mbc.E17-01-0001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5509426PMC
July 2017

Clinical Assessment of Urinary Tract Damage during Sustained-Release Estrogen Supplementation in Mice.

Comp Med 2017 02;67(1):11-21

Unit for Laboratory Animal Medicine (ULAM), University of Michigan, Ann Arbor, Michigan;, Email:

Estrogen supplementation is a key component of numerous mouse research models but can adversely affect the urinary system. The goal of this study was to develop a clinical scoring system and identify biomarkers of occult urinary tract lesions prior to the development of systemic illness in mice. Ovariectomized or sham-surgery SCID mice were implanted subcutaneously with a placebo pellet or one containing sustained-release estradiol (0.18 mg 60-d release 17β-estradiol). Mice were assessed twice weekly for 4 to 6 wk by using a clinical scoring system that included body condition, general activity, posture, hair coat, hydration, abdominal distension, urine staining of coat and skin, and ability to urinate. Samples were collected weekly for urinalysis, BUN, creatinine, and serum estradiol levels. Terminal samples were analyzed for histopathologic lesions. Compared with placebo controls, estradiolsupplemented mice had higher serum estradiol levels at weeks 2 and 3; significant differences in total clinical scores by the 3-wk time point; and in body condition, general activity, posture, hair coat, and urine staining scores by the 6-wk terminal time point. Urinary tract lesions included hydronephrosis, pyelonephritis, cystitis, and urolithiasis. All mice with urolithiasis had crystalluria, and 5 of the 6 mice with pyelonephritis or hydroureter had dilute urine (that is, specific gravity less than 1.030). However, these findings were not specific to mice with lesions. A total clinical score of 3.5 (maximum, 24) identified estradiol-supplemented mice with 83% specificity and 50% sensitivity, but no single clinical parameter, biomarker, or the total clinical score accurately predicted occult urinary tract lesions. Considering the lesions we observed, prudence is warranted when using pelleted sustained-release estradiol in mice, and important parameters to monitor for animal health include urine staining, body condition score, urine sediment, and urine specific gravity.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5310620PMC
February 2017

Chemical Exacerbation of Light-induced Retinal Degeneration in F344/N Rats in National Toxicology Program Rodent Bioassays.

Toxicol Pathol 2016 08 26;44(6):892-903. Epub 2016 May 26.

Cellular and Molecular Pathology Branch, National Toxicology Program, National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, North Carolina, USA

Retinal degeneration due to chronic ambient light exposure is a common spontaneous age-related finding in albino rats, but it can also be related to exposures associated with environmental chemicals and drugs. Typically, light-induced retinal degeneration has a central/hemispherical localization whereas chemical-induced retinal degeneration has a diffuse localization. This study was conducted to identify and characterize treatment-related retinal degeneration in National Toxicology Program rodent bioassays. A total of 3 chronic bioassays in F344/N rats (but not in B6C3F1/N mice) were identified that had treatment-related increases in retinal degeneration (kava kava extract, acrylamide, and leucomalachite green). A retrospective light microscopic evaluation of the retinas from rats in these 3 studies showed a dose-related increase in the frequencies of retinal degeneration, beginning with the loss of photoreceptor cells, followed by the inner nuclear layer cells. These dose-related increased frequencies of degenerative retinal lesions localized within the central/hemispherical region are suggestive of exacerbation of light-induced retinal degeneration.
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http://dx.doi.org/10.1177/0192623316650050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4965291PMC
August 2016

Achieving 12 Hour Normothermic Ex Situ Heart Perfusion: An Experience of 40 Porcine Hearts.

ASAIO J 2016 Jul-Aug;62(4):470-6

From the *Extracorporeal Life Support Laboratory, Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan; †Department of Surgery, Columbia University Medical Center, New York, New York; ‡In Vivo Animal Core, Unit for Laboratory Animal Medicine, University of Michigan Medical School, Ann Arbor, Michigan; §Advanced Platform Technology Center, VA Ann Arbor Health Care System, Ann Arbor, Michigan; ¶Department of Surgery, Section of Transplant Surgery, and ‖Department of Pediatric Cardiology, University of Michigan Health Systems, Ann Arbor, Michigan.

Although total body perfusion with extracorporeal life support (ECLS) can be maintained for weeks, individual organ perfusion beyond 12 hours has yet to be achieved clinically. Normothermic ex situ heart perfusion (ESHP) offers the potential for prolonged cardiac preservation. We developed an ESHP system to study the effect of perfusate variables on organ preservation, with the ultimate goal of extending organ perfusion for ≥24 hours. Forty porcine hearts were perfused for a target of 12 hours. Hearts that maintained electromechanical activity and had a <3× increase in vascular resistance were considered successful preservations. Perfusion variables, metabolic byproducts, and histopathology were monitored and sampled to identify factors associated with preservation failure. Twenty-two of 40 hearts were successfully preserved at 12 hours. Successful 12 hour experiments demonstrated lower potassium (4.3 ± 0.8 vs. 5.0 ± 1.2 mmol/L; p = 0.018) and lactate (3.5 ± 2.8 vs. 4.5 ± 2.9 mmol/L; p = 0.139) levels, and histopathology revealed less tissue damage (p = 0.003) and less weight gain (p = 0.072). Results of these early experiments suggest prolonged ESHP is feasible, and that elevated lactate and potassium levels are associated with organ failure. Further studies are necessary to identify the ideal perfusate for normothermic ESHP.
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http://dx.doi.org/10.1097/MAT.0000000000000382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4925299PMC
November 2017

A precursor-inducible zebrafish model of acute protoporphyria with hepatic protein aggregation and multiorganelle stress.

FASEB J 2016 05 2;30(5):1798-810. Epub 2016 Feb 2.

Department of Molecular and Integrative Physiology, Department of Internal Medicine, and Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, Michigan, USA

Protoporphyria is a metabolic disease that causes excess production of protoporphyrin IX (PP-IX), the final biosynthetic precursor to heme. Hepatic PP-IX accumulation may lead to end-stage liver disease. We tested the hypothesis that systemic administration of porphyrin precursors to zebrafish larvae results in protoporphyrin accumulation and a reproducible nongenetic porphyria model. Retro-orbital infusion of PP-IX or the iron chelator deferoxamine mesylate (DFO), with the first committed heme precursor α-aminolevulinic acid (ALA), generates high levels of PP-IX in zebrafish larvae. Exogenously infused or endogenously produced PP-IX accumulates preferentially in the liver of zebrafish larvae and peaks 1 to 3 d after infusion. Similar to patients with protoporphyria, PP-IX is excreted through the biliary system. Porphyrin accumulation in zebrafish liver causes multiorganelle protein aggregation as determined by mass spectrometry and immunoblotting. Endoplasmic reticulum stress and induction of autophagy were noted in zebrafish larvae and corroborated in 2 mouse models of protoporphyria. Furthermore, electron microscopy of zebrafish livers from larvae administered ALA + DFO showed hepatocyte autophagosomes, nuclear membrane ruffling, and porphyrin-containing vacuoles with endoplasmic reticulum distortion. In conclusion, systemic administration of the heme precursors PP-IX or ALA + DFO into zebrafish larvae provides a new model of acute protoporphyria with consequent hepatocyte protein aggregation and proteotoxic multiorganelle alterations and stress.-Elenbaas, J. S., Maitra, D., Liu, Y., Lentz, S. I., Nelson, B., Hoenerhoff, M. J., Shavit, J. A., Omary, M. B. A precursor-inducible zebrafish model of acute protoporphyria with hepatic protein aggregation and multiorganelle stress.
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http://dx.doi.org/10.1096/fj.201500111RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4836371PMC
May 2016

Renal Cell Carcinomas in Vinylidene Chloride-exposed Male B6C3F1 Mice Are Characterized by Oxidative Stress and TP53 Pathway Dysregulation.

Toxicol Pathol 2016 Jan 17;44(1):71-87. Epub 2015 Dec 17.

Cellular and Molecular Pathology Branch, Division of the National Toxicologic Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA

Vinylidene chloride (VDC) has been widely used in the production of plastics and flame retardants. Exposure of B6C3F1 mice to VDC in the 2-year National Toxicology Program carcinogenicity bioassay resulted in a dose-dependent increases in renal cell hyperplasia, renal cell adenoma, and renal cell carcinomas (RCCs). Among those differentially expressed genes from controls and RCC of VDC-exposed mice, there was an overrepresentation of genes from pathways associated with chronic xenobiotic and oxidative stress as well as c-Myc overexpression and dysregulation of TP53 cell cycle checkpoint and DNA damage repair pathways in RCC. Trend analysis comparing RCC, VDC-exposed kidney, and chamber control kidney showed a conservation of pathway dysregulation in terms of overrepresentation of xenobiotic and oxidative stress, and DNA damage and cell cycle checkpoint pathways in both VDC-exposed kidney and RCC, suggesting that these mechanisms play a role in the pathogenesis of RCC in VDC-exposed mice.
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http://dx.doi.org/10.1177/0192623315610820DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4752433PMC
January 2016