Curtis A. Machida

Curtis A. Machida Curtis A. Machida, Ph.D. (1982, Oregon Health & Science University)

Research Professor

Research Interests

Latent and Reactivated Herpesviruses in Symptomatic Endodontic Lesions (H. Li [Graduate
Endodontology Research], V. Chen, K. Kent, J. C. Baumgartner, and C. A. Machida)

Herpesviruses have recently been implicated in the pathogenesis of periapical pathosis, acute periodontitis, and acute inflammation of the gingiva and oral mucosa. Periapical pathosis has been hypothesized to be a multi-stage inflammatory endodontic disease initiated by migration of pathogenic microorganisms into the dental pulp and consequently leading to an influx of inflammatory cells containing latent herpesviruses. Irreversible pulpitis is an inflammation of the pulp tissue causing severe symptoms, including intolerable pain, thermal sensitivity, and hypersensitivity to mastication and palpation. The inflamed pulp, or pulpitis, eventually leads to pulpal necrosis and apical periodontitis. Periapical pathoses are severe endodontic diseases that result in the destruction of the bone surrounding the apices of the root, and can progress to periapical abscess and cellulitis and in severe cases to fascial space infections. The objectives of this research are to ascertain the presence of human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) in symptomatic irreversible pulpitis, acute periapical abscess, and persistent periapical lesions, and to determine the potential role of bone resorption-inducing cytokines and other immune factors in periapical pathosis.

Rapid and Quantitative Test for Cariogenic Streptococci and Assessment of Dental Caries Risk (S. Fazilat [Graduate Pediatric Dentistry Research], J. Kimmell, R. Sauerwein, T. Finlayson, H. Katz-Sagi, T. Maier, and C. A. Machida)

Caries treatment represents one of the most important aspects of dental practice, and caries management has historically focused on the removal of carious tissue and restoration of the tooth. Over the past several years, dentistry has undergone a paradigm shift in caries management towards improved diagnosis of noncavitated and incipient carious lesions and away from tooth restoration. The objectives of this research are to develop a more rapid and quantitative test for mutans streptococci, including the Streptococcus mutans and Streptococcus sobrinus strains, the major microbiological determinants for dental caries. The majority of commercialized tests evaluating microbiological determinants of dental caries utilize growth of mutans streptococci on selective agars in the presence of specific antibiotic, primarily high sucrose-containing medium and the antibiotic bacitracin. However, these tests are semiquantitative and require 48-72 hours for development of bacterial colonies. ATP bioluminescence has been widely used as a quantitative measure of microbial numbers. This research project will utilize bacitracin pre-selection and ATP bioluminescence to develop a rapid chairside test for mutans streptococci. This enhanced ATP bioluminescence test will examine and quantitate ATP contained only within mutans streptococci and will provide a direct indicator for the degree of risk for dental caries.

Effect of Archwire Ligation Technique on the Microbial Colonization of Cariogenic Microorganisms (P. Pellegrini [Graduate Orthodontics Research], R. Sauerwein, J. Kimmell, T. Finlayson, T. Maier, and C. A. Machida)

Cariogenic microorganisms that surround orthodontic appliances promote enamel demineralization and potential alteration in the appearance of the tooth surface. The purpose of this research is to measure and compare the levels of Streptococcus mutans and Lactobacilli from dental plaque at the bracket-tooth interface of two distinct orthodontic bracket types: One with a traditional elastomeric ligation and the other with self-ligation. Measurement of microorganism number will use ATP bioluminescence and viable cell plating on enriched and selective growth medium.

Research Support

National Institutes of Health
Oral Biotech
Oregon Clinical and Translational Research Institute
OHSU School of Dentistry

Representative Publications

Li B, Wyman TE, Moudgil T, Marracci GH, Ju CF, Machida CA. Nucleocytoplasmic export of type D simian retrovirus genomic RNA: Identification of important genetic subregions and interacting cellular proteins. Virology 1999; 264(1):37-54.

Li B, Axthelm MK, Machida CA. Simian retrovirus serogroup 5: partial gag-prt sequence and viral RNA distribution in an infected rhesus macaque. Virus Genes 2000; 21(3):241-8.

Li B, Nguyen S, Li X, Machida CA. Simian retrovirus vectors for gene transfer in nonhuman primate cells. Virus Research 2001; 75(2):155-68.

Li, B and Machida, CA. (2003) Development of simian retrovirus vectors for gene delivery. In: Virus for Gene Therapy: Methods and Protocols. (CA Machida, ed.) Humana Press.

Li, B, Li X, Bai Y, Hou J-W, Ma M, and Machida CA. (2004). Simian retrovirus constitutive transport element recognizes the ribosomal protein L10 and translocon protein in a yeast three-hybrid assay. Virus Research 99:69-80.

Machida, CA. (2005). Book review for Antisense Therapeutics: Second Edition. Humana Press. Totowa, New Jersey. Published in: Molecular Biotechnology 30:89.

Bai Y, Lu H, and Machida CA. (2006). CRM 1-mediated degradation and agonist-induced downregulation of beta 1-adrenergic receptor mRNAs. Biochem Biophysica Acta – Cell and Molecular Biology. 1763(10):1076-89.