No difference in 4-nitroquinoline induced tumorigenesis between germ-free and colonized mice.

Variations in oral bacterial communities have been linked to oral cancer suggesting that the oral microbiome is an etiological factor that can influence oral cancer development. The 4-nitroquinoline 1-oxide (4-NQO)-induced murine oral and esophageal cancer model is frequently used to assess the effects of preventive and/or therapeutic agents. We used this model to assess the impact of the microbiome on tumorigenesis using axenic (germ-free) and conventionally housed mice. Increased toxicity was observed in germ-free mice, however, no difference in tumor incidence, multiplicity, and size was observed. Transcriptional profiling of liver tissue from germ-free and conventionally housed mice identified 254 differentially expressed genes including ten cytochrome p450 enzymes, the largest family of phase-1 drug metabolizing enzymes in the liver. Gene ontology revealed that differentially expressed genes were enriched for liver steatosis, inflammation, and oxidative stress in livers of germ-free mice. Our observations emphasize the importance of the microbiome in mediating chemical toxicity at least in part by altering host gene expression. Studies on the role of the microbiome in chemical-induced cancer using germ-free animal models should consider the potential difference in dose due to the microbiome-mediated changes in host metabolizing capacity, which might influence the ability to draw conclusions especially for tumor induction models that are dose dependent.

Survey of Primary Contact Medical and Chiropractic Clinicians on Self-Reported Knowledge and Recognition of Mild Traumatic Brain Injuries: A Pilot Study.

OBJECTIVE: The purpose of this study was to assess the self-reported knowledge of concussion recognition and treatment with first-contact family medical and chiropractic practitioners by means of a pilot study of the need, construct validity, and feasibility for further investigation of mild traumatic brain injury (MTBI) knowledge base. METHODS: Two hundred forty-eight practicing chiropractic and 120 medical physicians in the south and northeastern sections of the United States were contacted by e-mail, telephone, and postal mail to answer an 18-item survey on knowledge, diagnosis, and common practice with respect to traumatic brain injury patients. Descriptive analysis was used to assess common trends. RESULTS: Twenty-three chiropractic and 11 medical primary care practitioners returned completed surveys, making this a low-power pilot study. The majority claimed confidence in diagnosis of MTBI, but a lack of knowledge of many of the assessment tools and the international guidelines. Chiropractic and medical clinicians revealed similar competencies and differing deficiencies. Both groups admitted infrequent diagnosis of MTBI in practice. There was recognition of major TBI signs, but lack of recognition or inquiry for subtle MTBI signs. CONCLUSIONS: There is a need and feasibility for further study of the knowledge transfer to the chiropractic physician with a larger population. These findings correlate with similar medical practitioner studies, and may also support previous findings of underreporting of the prevalence of MTBI. The survey instrument appears to provide valid data on knowledge of MTBIs, with some modifications.