Conditional TNF-α Overexpression in the Tooth and Alveolar Bone Results in Painful Pulpitis and Osteitis.

Tumor necrosis factor-α (TNF-α) is a proalgesic cytokine that is commonly expressed following tissue injury. TNF-α expression not only promotes inflammation but can also lead to pain hypersensitivity in nociceptors. With the established link between TNF-α and inflammatory pain, we identified its increased expression in the teeth of patients affected with caries and pulpitis. We generated a transgenic mouse model (TNF-α(glo)) that could be used to conditionally overexpress TNF-α. These mice were bred with a dentin matrix protein 1 (DMP1)-Cre line for overexpression of TNF-α in both the tooth pulp and bone to study oral pain that would result from subsequent development of pulpitis and bone loss. The resulting DMP1/TNF-α(glo) mice show inflammation in the tooth pulp that resembles pulpitis while also displaying periodontal bone loss. Inflammatory infiltrates and enlarged blood vessels were observed in the tooth pulp. Pulpitis and osteitis affected the nociceptive neurons innervating the orofacial region by causing increased expression of inflammatory cytokines within the trigeminal ganglia. With this new mouse model morphologically mimicking pulpitis and osteitis, we tested it for signs of oral pain with an oral function assay (dolognawmeter). This assay/device records the time required by a mouse to complete a discrete gnawing task. The duration of gnawing required by the DMP1/TNF-α(glo) mice to complete the task was greater than that for the controls; extended gnaw time in a dolognawmeter indicates reduced orofacial function. With the DMP1/TNF-α(glo) mice, we have shown that TNF-α expression alone can produce inflammation similar to pulpitis and osteitis and that this mouse model can be used to study dental inflammatory pain.

Disposable versus reusable biopsy forceps for colorectal epithelial cell proliferation in humans.

The performance of various measures of rectal mucosal proliferation has been evaluated in the literature, but the performance of the forceps used to obtain the tissue has received little attention. We used data from two large studies of proliferation at a single institution to compare reusable and disposable endoscopic forceps. Endoscopic pinch biopsies were taken 10 cm from the anal verge using either reusable or disposable, oval-cupped, sheathed forceps. The specimens were fixed, embedded, and sectioned, taking care to orient the specimens longitudinally. Five sections were placed on each slide. We determined how many slides did not contain eight scorable crypts (inadequate) and how many sections were necessary to identify eight complete crypts. There were 395 subjects who had biopsies taken with reusable forceps and 185 subjects who had biopsies taken with disposable forceps. The specimens were inadequate in 27.6% of the reusable forceps specimens versus 2.7% of the disposable forceps (P < 0.0001). The mean number of tissue sections necessary to identify eight scorable crypts for the reusable forceps was 3.82 (SD, 0.87) compared with 3.17 (SD, 0.83) for disposable forceps (P = 0.0001). The specimens taken with the disposable forceps were better, probably because the forceps were sharper. We believe that the better quality of the specimens and the sterility justify the higher cost of disposable forceps. We would urge investigators in proliferation studies to evaluate the biopsy equipment as carefully as they evaluate other aspects of their methods.

Elevated carbon dioxide influences yield and photosynthetic responses of hydroponically-grown [correction of glown] sweetpotato.

The response of 'TI-155' and 'Georgia Jet' sweetpotato cultivars to elevated CO2 concentrations of 400 (ambient), 750 and 1000 micromoles mol-1 were evaluated under controlled environment conditions using the nutrient film technique (NFT). Growth chamber conditions included photosynthetic photon flux (PPF) of 600 micromoles m-2 s-1, 14/10 light/dark period, and 70% +/- 5% RH. Plants were grown using a modified half-Hoagland nutrient solution with a pH range of 5.5-6.0 and an electrical conductivity of 0.12 S m-1. Gas exchange measurements were made using infrared gas analysis, an open-flow gas exchange system, and a controlled-climate cuvette. Photosynthetic (Pn) measurements were made at CO2 ranges of 50 to 1000 micromoles mol-1. Storage root yield/plant increased with CO2 up to 750 but declined at 1000 micromoles mol-1. Storage root dry matter (DM) and foliage dry weight increased with increasing CO2. Harvest index (HI) for both cultivars was highest at 750 micromoles mol-1. The PPF vs Pn curves were typical for C3 plants with saturation occurring at approximately 600 micromoles m-2 s-1. CO2 concentration did not significantly influence net Pn, transpiration, water-use-efficiency (WUE), and stomatal conductance. As measurement CO2 concentration increased, net Pn and WUE increased while transpiration and stomatal conductance decreased.