David Chu

All Publications

• Longevity in a fish bowl LAB ANIMAL Chu, D. 2016; 45 (3): 93-93

  View details for Web of Science ID 000371197200014

  View details for PubMedID 26886667

• A "Pedi" Cures All: Toenail Trimming and the Treatment of Ulcerative Dermatitis in Mice PLOS ONE Adams, S. C., Garner, J. P., Felt, S. A., Geronimo, J. T., Chu, D. K. 2016; 11 (1)

  Abstract

  Ulcerative Dermatitis (UD) is the most common cause of unplanned euthanasia in mice used in research, with prevalence rates reported between 4 and 21%. UD is characterized by a deep, ulcerative lesion that appears most commonly over the dorsal neck and is attendant with an intense pruritus. The underlying cause of UD is currently unknown, and as a consequence, there are no directed therapies that resolve lesions reliably. However, there is a growing body of evidence that suggests a behavioral component to the onset, maintenance, and progression of UD lesions. Scratching behavior in response to the intense pruritus associated with UD lesions may be an effective target for interventional therapies. We hypothesized that interfering with scratching behavior by trimming the toenails of mice with UD, would resolve UD lesions. To test this hypothesis, we first evaluated the efficacy of toenail trims with a single application of Vetericyn at the time of treatment versus our previous standard of care, topical Tresaderm applied daily. We found that toenail trims were significantly more effective at resolving lesions (n = 39 toenail trims, n = 100 Tresaderm, p<0.0001) with 93.3% of animals healing by 14 days (median time to lesion resolution). Furthermore, dorsal neck lesions did not recur by 42 days after a single toenail trim (n = 54); however, flank lesions did not resolve and the outcome of the two lesion distributions following treatment were significantly different (p<0.0001). Finally, we implemented toenail trims at an institutional level and found similar efficacies (approximately 90%) for toenail trims regardless of one-time topical supplement used (triple antibiotic ointment, Tresaderm, and Vetericyn, n = 55, 58, 18, p = 0.63). This is the first report of a highly effective treatment for one of the most serious welfare issues in laboratory mice.

  View details for DOI 10.1371/journal.pone.0144871

  View details for Web of Science ID 000367805100014

  View details for PubMedCentralID PMC4703297

• Three cheers for the three-spined stickleback Heng, K., Thompson, A., Chu, D., Kingsley, D. M. Nature Publishing. 2016 ; Lab Animal (volumn 45 number 11): 421
• Processing and secretion of ROP13: A unique Toxoplasma effector protein INTERNATIONAL JOURNAL FOR PARASITOLOGY Turetzky, J. M., Chu, D. K., Hajagos, B. E., Bradley, P. J. 2010; 40 (9): 1037-1044

  Abstract

  Like most intracellular pathogens, Toxoplasma synthesizes and secretes an arsenal of proteins to successfully invade its host cell and hijack host functions for intracellular survival. The rhoptries are key secretory organelles that inject proteins into the host cell where they are positioned to co-opt host processes, although little is known regarding how these proteins exert their functions. We show here that the rhoptry protein ROP13 is synthesized as a pre-pro-protein that is processed in the parasite. Processing occurs at a conserved SphiXE cleavage site as mutagenesis of glutamic acid to alanine at the P1 position disrupts ROP13 maturation. We also demonstrate that processing of the prodomain is not necessary for rhoptry targeting and secretion. While gene disruption reveals that ROP13 is not essential for growth in fibroblasts in vitro or for virulence in vivo, we find that ROP13 is a soluble effector protein that can access the cytoplasm of host cells. Exogenously expressed ROP13 in human cells remains cytosolic but also appears toxic, suggesting that over-expression of this effector protein is disrupting some function within the host cell.

  View details for DOI 10.1016/j.ijpara.2010.02.014

  View details for Web of Science ID 000280022700006

  View details for PubMedID 20359481

• Alternative Group Housing for Small Bullfrog Colonies Chu, D. American Association for Laboratory Animal Science. Memphis, TN. 2010 ; Tech Talk (15(3)): 3
• Uterine epithelioid trophoblastic tumor in an African green monkey (Chlorocebus aethiops sabaeus) 56th National Meeting of the American-Association-for-Laboratory-Animal-Science (AALAS) Chu, D., Shih, I., Knezevich, M., Sheth, S. AMER ASSOC LABORATORY ANIMAL SCIENCE. 2007: 92–96

  Abstract

  A uterine mass was detected on physical exam in a multiparous African green monkey as an incidental finding, and the well-circumscribed mass was removed via hysterectomy. Histologically, the mass consisted of sheets, nests, and cords of uniform intermediate trophoblastic cells with eosinophilic or clear cytoplasm. These neoplastic cells aggregated around blood vessels, forming islands of viable tumor cells amid extensive areas of coagulative necrosis with calcification in a 'geographic' pattern of necrosis. Immunohistochemistry of the trophoblastic cells revealed strong and diffuse staining for pancytokeratin AE1/3 and p63, with weak and moderate staining for human placental lactogen and placental alkaline phosphatase, respectively. Immunohistochemical staining for smooth muscle actin, epithelial membrane antigen, and human chorionic gonadotropin was negative. Overall, the histologic and immunohistochemical features of this tumor were consistent with those of epithelioid trophoblastic tumor. This rare tumor type has not been reported previously to occur in African green monkeys.

  View details for Web of Science ID 000245325200015

  View details for PubMedID 17343360

• Comparing isoflurane with tribromoethanol anesthesia for echocardiographic phenotyping of transgenic mice JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE Chu, D. K., Jordan, M. C., Kim, J. K., Couto, M. A., Roos, K. P. 2006; 45 (4): 8-13

  Abstract

  Cardiac phenotyping of transgenic mice typically requires anesthesia. Chemical-grade tribromoethanol (TBE) is commonly used for this purpose due to its relatively short duration of action, modest cardiodepressive effects, and its noncontrolled status. In the present study, we used both genders of C57BL/6;C3H-Tg(Slc8a1)hKdp transgenic (TG) mice and C57BL/6;C3H wild-type (WT) mice to evaluate isoflurane (ISF) as a pharmaceutical-grade alternative to TBE for echocardiography and electrocardiography. Baseline target physiologic heart rates (beats per minute) were established by use of telemetry as 544 +/- 10 in WT mice and 580 +/- 21 in TG mice. TG and WT animals were anesthetized with either 0.8% to 1% inhalational ISF or 250 mg/kg intraperitoneal TBE. The following parameters were measured or calculated according to the previously defined physiologic heart rates: end diastolic and systolic dimensions; posterior wall and ventricular septal thicknesses; left ventricular mass, aortic ejection times; left ventricular fractional shortening; velocity of circumferential fiber shortening; and left ventricular ejection fraction. No significant difference between anesthetics was found for any measured cardiac parameters. However, the time required for data acquisition was significantly shorter for ISF (10 min) than for TBE (14 min). This study demonstrates that comparable echocardiographic results can be obtained at higher throughput by use of pharmaceuticalgrade ISF than with chemical-grade TBE.

  View details for Web of Science ID 000239352300002

  View details for PubMedID 16884172

• Arthropod infestation in a colony of mice LAB ANIMAL Chu, D. K., Couto, M. A. 2005; 34 (9): 25-27

  View details for Web of Science ID 000232348700005

  View details for PubMedID 16195733