Production of a gonadotropin-releasing hormone 2 receptor knockdown (GNRHR2 KD) swine line.

Swine are the only livestock species that produce both the second mammalian isoform of gonadotropin-releasing hormone (GNRH2) and its receptor (GNRHR2). Previously, we reported that GNRH2 and GNRHR2 mediate LH-independent testosterone secretion from porcine testes. To further explore this ligand-receptor complex, a pig model with reduced GNRHR2 expression was developed. Small hairpin RNA sequences targeting porcine GNRHR2 were subcloned into a lentiviral-based vector, lentiviral particles were generated and microinjected into the perivitelline space of zygotes, and embryos were transferred into a recipient. One GNRHR2 knockdown (KD) female was born that subsequently produced 80 piglets from 6 litters with 46 hemizygous progeny (57% transgenic). Hemizygous GNRHR2 KD (n = 10) and littermate control (n = 7) males were monitored at 40, 100, 150, 190, 225 and 300 days of age; body weight and testis size were measured and serum was isolated and assayed for testosterone and luteinizing hormone (LH) concentrations. Body weight of GNRHR2 KD boars was not different from littermate controls (P = 0.14), but testes were smaller (P < 0.05; 331.8 vs. 374.8 cm3, respectively). Testosterone concentrations tended (P = 0.06) to be reduced in GNRHR2 KD (1.6 ng/ml) compared to littermate control (4.2 ng/ml) males, but LH levels were similar (P = 0.47). The abundance of GNRHR2 mRNA was reduced (P < 0.001) by 69% in testicular tissue from mature GNRHR2 KD (n = 5) versus littermate control (n = 4) animals. These swine represent the first genetically-engineered model to elucidate the function of GNRH2 and its receptor in mammals.

IL-33 increases ST2+ Tregs and promotes metastatic tumour growth in the lungs in an amphiregulin-dependent manner.

Regulatory T cells (Tregs) facilitate primary and metastatic tumour growth through the suppression of anti-tumour immunity. Emerging evidence suggests a distinct role for Tregs in mediating tissue repair and barrier integrity in the lungs by IL-33 mediated production of the growth factor amphiregulin (AREG). Dependent on the type of cancer and local microenvironment, AREG may induce tumour cell proliferation, invasion, migration or resistance to apoptosis by signaling through the epidermal growth factor receptor (EGFR). We have found that IL-33 is dramatically increased in and around metastatic tumour foci in the lungs of mice bearing orthotopic murine mammary tumours. We observed that Tregs express significantly more of the IL-33 receptor, ST2, relative to conventional T cells, that ST2+ Tregs accumulate in the lungs of metastatic tumour-bearing mice, and that ST2+ Tregs produce significantly more AREG than ST2- Tregs. The intranasal administration of recombinant IL-33 increased the proportion of AREG producing ST2+ Tregs and enhanced the level of phosphorylated EGFR in the metastatic lungs. While recombinant AREG did not impact mammary tumour cell proliferation in vitro despite inducing a dose-dependent increase in phosphorylated EGFR, intranasal administration of AREG resulted in a ten-fold increase in pulmonary metastatic tumour burden in vivo. Further, the intranasal administration of recombinant IL-33 significantly increased metastatic tumour burden in the lungs in an amphiregulin-dependent manner. These data identify ST2+ Tregs as a microenvironmental source of AREG in the lungs of mice with orthotopic metastatic mammary tumours and highlight an important role for AREG in promoting metastatic tumour growth in the lungs.

Endodontic working length assessment. Comparison of storage phosphor digital imaging and radiographic film.

OBJECTIVE: This study compared the difference in interpretation of the position of endodontic file tips between two imaging systems: photostimulable storage phosphor luminescence imaging versus radiographic film. STUDY DESIGN: Thirteen patients were selected at random. Preoperative and trial file length radiographs were made with a dual image receptor composed of a Digora Digital Imaging Plate and a piece of Ektaspeed Plus film. Exposure techniques for E-speed film were used. Root length and file length measurements were made from digital images with the Digora system's measuring tools. Measurements were also made on radiographic film with a 7 x measuring magnifier. Root length, file length, and their difference were compared for both film and digital images. RESULTS: Differences were found to be less in digital than in film images. Photostimulable storage phosphor luminescence imaging performed similarly to Ektaspeed Plus film for measuring root lengths, but file tip positions (especially of small file sizes) were difficult to visualize with E-speed film. CONCLUSIONS: The smaller difference between file tip and root apex found with digital imaging suggests that this technique is more accurate to assess trial file length. This imaging modality for assessing file positions during root canal treatment may be beneficial to the practitioner.

Effect of the geometry of the intraoral position-indicating device on effective dose.

OBJECTIVE: The objective of this study was to calculate and compare the effective dose and to estimate risk from the use of intraoral position-indicating devices of differing geometries. STUDY DESIGN: Thermoluminescent dosimeters were placed at selected sites in the upper portion of a tissue-equivalent human phantom to record the equivalent dose to weighted tissues and organs. The phantom was exposed to simulated complete mouth surveys with either a long (29.8 cm) or short (19.6 cm) round open-end position-indicating device, a long (35.3 cm) or short (23.3 cm) rectangular open-end position-indicating device, or a pointed (29.6 cm) closed-end position-indicating device. RESULTS: The effective dose was calculated as the sum of the equivalent doses to each organ or tissue multiplied by that organ or tissue's weighting factor. The salivary glands were included as part of the remainder. The effective dose ranged from 362 micro Sv for the pointed position-indicating device, to 63 micro Sv for both the long and the short rectangular position-indicating devices. CONCLUSIONS: These effective doses were calculated to represent a probability for stochastic effects that range in magnitude from 26 x 10(-6) to 4.6 x 10(-6).

A pilot study of 2 methods for control of dental unit biofilms.

OBJECTIVE: This pilot study was conducted to clinically evaluate 2 different concentrations of sodium hypochlorite for the control of dental unit biofilms and to evaluate the efficacy of pasteurizing dental treatment water for patient care. METHOD AND MATERIALS: Two dental units with no prior chemical treatment were retrofitted with self-contained water systems for this study. One dental unit was treated with 5,000 ppm of sodium hypochlorite and the other with 1,500 ppm. Treatment consisted of a 10-minute contact with the dental unit water lines, followed by a flush with a buffer solution. A pasteurizer was equipped with autoclavable spigots to provide dental treatment water. Heterotrophic Plate Count Samplers (Millipore) water sampler kits were used to quantify microbial contamination as absolute colony-forming units per millimeter. Scanning electron micrographs were taken of water line lumens to compare pretreatment and posttreatment biofilms. RESULTS: Pasteurized water was significantly less contaminated than was tap water. No significant difference in contamination was found between the 5,000 ppm and 1,500 ppm treatment chairs, either in the reservoir water or effluent water. Scanning electron micrographs demonstrated removal of the biofilms after sodium hypochlorite treatments, regardless of the concentration used. CONCLUSION: There was no significant difference between the abilities of 5,000- and 1,500-ppm concentrations of sodium hypochlorite to control contamination of dental treatment water and biofilms. Pasteurization of tap water can reduce contamination; this water can be used as acceptable dental treatment water (< 200 CFU/mL).

Temporomandibular joint space analysis.

Radiographic interpretation of the temporomandibular joint (TMJ) frequently revolves around a determination of condyle concentricity. The purpose of this study was to establish the relationship between actual and radiographic joint space, the latter determined from lateral corrected tomograms made by a Soredex Scanora. Vacuum-formed shims were placed over the condylar heads of a human skull and tomographic images of the TMJs were made. These shims were measured using a caliper and the mean thickness was used to represent actual joint space. Thickness of the shims fabricated for the right condyle varied from .15 mm (1 shim) to 1.60 mm (5 shims). The resulting radiographs were measured to determine the extent to which actual and radiographic joint space compared.

E-learning and the future of dental education: opinions of administrators and information technology specialists.

The digital revolution and growth of the Internet have led to many innovations in the area of electronic learning (e-learning). To survive and prosper, educators must be prepared to respond creatively to these changes. Administrators and information technology specialists at six dental schools and their parent institutions were interviewed regarding their opinions of the impact that e-learning will have on the future of dental education. Interview questions encompassed vision, rate of change, challenges, role of faculty, resources, enrolment, collaboration, responsibility for course design and content, mission and fate of the institution. The objective of this qualitative study was to sample the opinions of educational administrators and information technology specialists from selected US universities regarding the impact of e-learning on dental education to detect trends in their attitudes. Responses to the survey indicated disagreement between administrators and informational technology specialists regarding the rate of change, generation of resources, impact on enrolment, responsibility for course design and content, mission and fate of the university. General agreement was noted with regard to vision, challenges, role of faculty and need for collaboration.

Calcification of the interclinoid and petroclinoid ligaments of sella turcica: a radiographic study of the prevalence.

OBJECTIVES: The purpose of this study was to evaluate the prevalence of calcifications of the sella turcica, in particular, calcification of the interclinoid and petroclinoid ligaments (PCL). DESIGN: Radiographic analysis of preoperative cephalometric film images. SETTING AND SAMPLE POPULATION: Lateral cephlometric radiographs of 255 subjects presenting for orthodontic evaluation were reviewed. The number of subjects selected for this study was determined by power analysis. EXPERIMENTAL VARIABLE: Two calibrated raters reviewed cephalometric projections and scored the films using a standardized rating scale. OUTCOME MEASURE: The rating scale classified interclinoid ligaments (ICL) into one of four categories depending on the degree of calcification and PCLs as either, no calcification, partial or complete calcification. RESULTS: Of all subjects, calcification of the ICL ranged from 39% rated as more than half calcified to 8% completely calcified. Petroclinoid analysis revealed 67% with no calcification, 23% with partial calcification and 9% completely calcified. Spearman's correlations were computed between age and the degree of calcification and between the degree of calcification for these two ligaments with a significant association between age and degree of calcification in the PCL, r = 0.185 (p = 0.003) and a significant association between the degree of calcification in the petroclinoid and ICLs, r = 0.186 (p = 0.003). In addition, chi-squared tests demonstrated statistically significant associations between the presence of calcification in the PCL to the distribution of age (p = 0.041) and between the presence of calcification in the ICL to the distribution of age (p = 0.045). CONCLUSION: As calcification of these ligaments has suggestive associations with disease entities, their recognition as a variant of normal anatomy should be evaluated when assessing cephalometric radiographs.

Cutaneous odontogenic sinus tract to the chin: a case report.

We report a case of cutaneous odontogenic sinus tract to the chin. The patient first noticed the cutaneous condition in 1977. Inappropriate medical and dental treatment was ineffective. Correct diagnosis and treatment was completed in 1993. We offer diagnostic and treatment guidelines for the management of similar cases.

Influence of the digital image display monitor on observer performance.

OBJECTIVE: To assess the influence of the display monitor on observer performance. MATERIAL AND METHODS: Artificial enamel lesions were created in 40 extracted teeth at random using 1/4 and 1/2 round burs. Teeth were mounted in dental stone blocks to simulate a hemidentition. Approximate exposures were recorded at 70 kVp using a Digota (Soredex, Orion Corp, Helsinki, Finland) digital imaging system, calibrated to achieve optimum density. Six dentists rated each image on a five-point scale for the presence or absence of a lesion. Radiographic images were viewed on the following monitors: (1) AlphaScan 711 (Sampo Corp.); (2) Multiscan 17 Se II (Sony Electronics Inc.); (3) DS 2000 (Clinton Electronics Corp.) and (4) Latitude CP Laptop (Dell Computer Corp.). Raters were allowed to magnify and to adjust density and contrast of each image at will. Receiver Operating Characteristic (ROC) analysis was performed and curves were plotted for each image. Data was subjected to repeated measures analysis of variance and ordinal logistic regression to test for significance between variables and to determine odds ratios. RESULTS: Mean ROC curve areas ranged from 0.8728 for the Sampo monitor to 0.8395 for the Sony. Repeated measures analysis of variance showed significant differences between observers (P < 0.0001), lesion size (P < 0.0001), examiner/monitor interaction (P < 0.033) and examiner/block interaction (P < 0.013). However, no significant difference was found between monitors. CONCLUSION: This study suggests that observer performance is independent of the visual characteristics of the display monitor.

Effect of different background lighting conditions on diagnostic performance of digital and film images.

OBJECTIVE: To compare the performance of a photostimulable phosphor (PSP) imaging system with radiographic film for the detection of approximal lesions under two background lighting conditions. METHODS: Bitewing exposures were made of the extracted human teeth with artificial approximal lesions using D-speed and E-speed radiographic film and a PSP imaging plate. Eight dentists rated 12 approximal surfaces in each image on a 5-point scale. Images were viewed with overhead fluorescent room lighting on and off. ROC curves were generated for each image receptor and lighting condition. Repeated measures analysis of variance ANOVA tested differences between observers, lesion size, image receptor, lighting condition. RESULTS: Mean ROC curve areas for D-speed film viewed in full ambient light scored highest (0.8030) followed by E-speed film using dark conditions (0.7386). The lowest mean curve area was found when PSP (enhanced mode) images were viewed in a dark room (0.6726). Significant differences were found between observers, lesion size, image receptor and image receptor-lesion size interaction. No significant difference was found with background lighting. CONCLUSIONS: Background lighting does not appear to effect the ability to detect artificial approximal lesions.

Clinical benefits of oral irrigation for periodontitis are related to reduction of pro-inflammatory cytokine levels and plaque.

BACKGROUND: Although a growing body of evidence indicates that oral irrigation with water has therapeutic benefits in periodontitis, the mechanisms of action have not been elucidated. The aims of this study were: (1) to analyze the effects of oral irrigation (Water Pik Oral Irrigator) on the clinical signs of adult periodontitis (AP) and on the levels of interleukin-1 beta (IL-beta), prostaglandin-E2 (PGE2), interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) in GCF, and (2) to analyze the influence of the periodontitis-related IL-1 genotype (IL-1GT) on these variables. METHOD: A single-center, blinded study in otherwise healthy humans (n= 52) with localized mild to moderate AP was carried out, using the following groups: group A (n= 12), no oral hygiene for 14 days; group B (n=20), routine oral hygiene (ROH) for 14 days; group C (n=20), supra-gingival oral irrigation plus ROH for 14 days. Group A patients were crossed-over to group C for 14 days (=day 28) after a professional prophylaxis. Group assignment was randomized by a coin toss, with the exception of group A subjects, who were self-selected as per recommendations of the internal review board for human subjects. GCF was sampled from 3 study teeth per patient and analyzed for IL-1 beta, PGE2, IL-10 and IFN gamma by ELISA on days 0, 7, 14 and 28. Probing pocket depths (PPD), clinical attachment levels (CAL), bleeding on probing (BOP), gingival index (GI) and plaque index (PI) were measured by a calibrated examiner (TWS) on days 0, 14 and 28. Analysis of covariance was performed using SAS 6.12 and Proc Mixed with group and IL-1GT as the factors and the baseline levels as the covariate, with output being least squares means and least significant difference (LSD). Significant differences were declared if the p-value for the F-statistic was < or =0.05. RESULTS: Oral irrigation plus ROH resulted in a significant reduction in PPD, BOP, GI and PI, as well as IL-beta levels by 7 days and PGE2 levels by 14 days, relative to ROH or no oral hygiene. Interestingly, decreased IL-1 beta levels in patients using oral irrigation plus ROH was accompanied by a trend for increased levels of the "anti-inflammatory" cytokine IL-10. ROH reduced GI, BOP and PI, and PGE2 levels by 14 days, but had no effect on IL-1 beta or IL-10 levels relative to no oral hygiene. The effects of no oral hygiene were reversed by a prophy followed by oral irrigation plus ROH for 14 days. No clinical differences were evident between IL-1 GT (+) patients (n= 1) and GT (-) patients (n=40), but the former had significantly elevated levels of GCF IL-10 and borderline increases in IL-1 beta (p=0.07). CONCLUSIONS: Oral irrigation with water for 14 days had an improved therapeutic benefit for AP over that of routine oral hygiene alone and this improvement was accompanied by a down-modulation of the pro-inflammatory cytokine profile in GCF.