Subgingival uptake and retention of stannous fluoride from dentifrice: Gingival crevicular fluid concentrations in sulci post-brushing.

PURPOSE: To examine the delivery of stannous fluoride to subgingival sulci following toothpaste use in a clinical population. METHODS: This was a controlled, single-site study. 23 subjects with at least 20 dental pockets, 2-4 mm with bleeding, who had not used a stannous fluoride dentifrice in the last 3 months were enrolled. After a 2-week washout period, 20 subjects returned for a baseline visit. They were instructed to refrain from brushing the night before the baseline visit. GCF samples were taken from up to 10 sites identified as sampling sites. Subjects were then given a 0.454% stannous fluoride dentifrice and soft manual toothbrush and asked to brush for 1 minute. 30 minutes after brushing, GCF was re-sampled. Subjects continued using the stannous fluoride dentifrice and soft manual toothbrush at home, twice daily for 2 weeks, in place of their usual hygiene products. At Days 1 and 14, subjects returned to the site, and 12 hours post-brushing GCF samples were taken. The samples were analyzed by ICP-MS (inductively coupled plasma mass spectrometry). A Wilcoxon signed-rank test was performed to determine the difference between post-baseline visits and baseline. Statistical tests were 2-sided using a 5% significance level. RESULTS: 20 subjects completed the trial. Significant levels of tin, a marker for stannous fluoride, were detected 30 minutes after brushing at sampling sites of 2-4 mm. The median tin level in gingival crevicular fluid (GCF) was 24.59 ng/µl, which was highly significant versus baseline (P< 0.0001). Tin levels sampled in GCF 12 hours after brushing on Days 1 and 14 were highly significant versus Baseline (P< 0.0001), showing an increasing trend with continued use. CLINICAL SIGNIFICANCE: Stannous fluoride was found to penetrate sampling sites from 2-4 mm and was retained for 12 hours. Subgingival uptake and retention of stannous fluoride following toothbrushing may play a role in detoxification effects on microbial biofilms and may contribute to the therapeutic efficacy of stannous fluoride dentifrices in promoting gingival health.

Kras(G12D) and Smad4/Dpc4 haploinsufficiency cooperate to induce mucinous cystic neoplasms and invasive adenocarcinoma of the pancreas.

Oncogenic Kras initiates pancreatic tumorigenesis, while subsequent genetic events shape the resultant disease. We show here that concomitant expression of Kras(G12D) and haploinsufficiency of the Smad4/Dpc4 tumor suppressor gene engenders a distinct class of pancreatic tumors, mucinous cystic neoplasms (MCNs), which culminate in invasive ductal adenocarcinomas. Disease evolves along a progression scheme analogous to, but distinct from, the classical PanIN-to-ductal adenocarcinoma sequence, and also portends a markedly different prognosis. Progression of MCNs is accompanied by LOH of Dpc4 and mutation of either p53 or p16. Thus, these distinct phenotypic routes to invasive adenocarcinoma nevertheless share the same overall mutational spectra. Our findings suggest that the sequence, as well as the context, in which these critical mutations are acquired helps determine the ensuing pathology.

Trp53R172H and KrasG12D cooperate to promote chromosomal instability and widely metastatic pancreatic ductal adenocarcinoma in mice.

To define the genetic requirements for pancreatic ductal adenocarcinoma (PDA), we have targeted concomitant endogenous expression of Trp53(R172H) and Kras(G12D) to the mouse pancreas, revealing the cooperative development of invasive and widely metastatic carcinoma that recapitulates the human disease. The primary carcinomas and metastases demonstrate a high degree of genomic instability manifested by nonreciprocal translocations without obvious telomere erosion-hallmarks of human carcinomas not typically observed in mice. No mutations were discovered in other cardinal tumor suppressor gene pathways, which, together with previous results, suggests that there are distinct genetic pathways to PDA with different biological behaviors. These findings have clear implications for understanding mechanisms of disease pathogenesis, and for the development of detection and targeted treatment strategies.

Dynamics of the immune reaction to pancreatic cancer from inception to invasion.

The dynamics of cancer immunosurveillance remain incompletely understood, hampering efforts to develop immunotherapy of cancer. We evaluated the evolving in vivo immune response to a spontaneous tumor in a genetically defined mouse model of pancreatic ductal adenocarcinoma from the inception of preinvasive disease to invasive cancer. We observed a prominent leukocytic infiltration even around the lowest grade preinvasive lesions, but immunosuppressive cells, including tumor-associated macrophages, myeloid-derived suppressor cells (MDSC), and regulatory T cells (Treg), dominated the early response and persisted through invasive cancer. Effector T cells, however, were scarce in preinvasive lesions, found in only a subset of advanced cancers, and showed no evidence of activation. The lack of tumor-infiltrating effector T cells strongly correlated with the presence of intratumoral MDSC with a near mutual exclusion. In vitro, we found that MDSC suppressed T-cell proliferation. Overall, our results show that suppressive cells of the host immune system appear early during pancreatic tumorigenesis, preceding and outweighing antitumor cellular immunity, and likely contribute to disease progression. Thus, in contrast to the hypothesis that an early "elimination phase" of cancer immunosurveillance is eventually overwhelmed by a growing invasive tumor, our findings suggest that productive tumor immunity may be undermined from the start. Efforts to test potent inhibitors of MDSC, tumor-associated macrophages, and Treg, particularly early in the disease represent important next steps for developing novel immunotherapy of cancer.

Histological and Gene Expression Analysis of the Effects of Menopause Status and Hormone Therapy on the Vaginal Introitus and Labia Majora.

BACKGROUND: The study aimed to determine the effect of menopausal status and hormone therapy on the introitus and labia majora at the levels of histology and gene expression. METHODS: Three cohorts of 10 women each (pre-menopause, post-menopause and post-menopause + hormone therapy) were selected based on the presentation of clinical atrophy and vaginal pH. Biopsies were obtained from the introitus (fourchette) and labia majora and processed for histology and gene expression analyses with microarrays. Other data collected included self-assessed symptoms, serum estradiol, testosterone, serum hormone binding globulin and the pH of the vagina and labia majora. RESULTS: The introitus appears exquisitely sensitive to hormone status. Dramatic changes were observed in histology including a thinning of the epithelium in post-menopausal subjects with vaginal atrophy. Furthermore, there was differential expression of many genes that may contribute to tissue remodeling in the atrophic introitus. Levels of expression of genes associated with wound healing, angiogenesis, cell migration/locomotion, dermal structure, apoptosis, inflammation, epithelial cell differentiation, fatty acid, carbohydrate and steroid metabolism were significantly different in the cohort exhibiting atrophy of the introitus. While changes were also observed at the labia, that site was considerably less sensitive to hormone status. The gene expression changes observed at the introitus in this study were very similar to those reported previously in the atrophic vagina providing further evidence that these changes are associated with atrophy. CONCLUSIONS: The histological and gene expression changes occurring within the introitus after menopause may contribute to the constellation of symptoms that constitute the genitourinary syndrome of menopause.

Wnt/beta-catenin signaling is required for development of the exocrine pancreas.

BACKGROUND: Beta-catenin is an essential mediator of canonical Wnt signaling and a central component of the cadherin-catenin epithelial adhesion complex. Dysregulation of beta-catenin expression has been described in pancreatic neoplasia. Newly published studies have suggested that beta-catenin is critical for normal pancreatic development although these reports reached somewhat different conclusions. In addition, the molecular mechanisms by which loss of beta-catenin affects pancreas development are not well understood. The goals of this study then were; 1] to further investigate the role of beta-catenin in pancreatic development using a conditional knockout approach and 2] to identify possible mechanisms by which loss of beta-catenin disrupts pancreatic development. A Pdx1-cre mouse line was used to delete a floxed beta-catenin allele specifically in the developing pancreas, and embryonic pancreata were studied by immunohistochemistry and microarray analysis. RESULTS: Pdx1-cre floxed beta-catenin animals were viable but demonstrated small body size and shortened median survival. The pancreata from knockout mice were hypoplastic and histologically demonstrated a striking paucity of exocrine pancreas, acinar to duct metaplasia, but generally intact pancreatic islets containing all lineages of endocrine cells. In animals with extensive acinar hypoplasia, putative hepatocyte transdifferention was occasionally observed. Obvious and uniform pancreatic hypoplasia was observed by embryonic day E16.5. Transcriptional profiling of Pdx1-cre floxed beta-catenin embryonic pancreata at E14.5, before there was a morphological phenotype, revealed significant decreases in the beta-catenin target gene N-myc, and the basic HLH transcription factor PTF1, and an increase of several pancreatic zymogens compared to control animals. By E16.5, there was a dramatic loss of exocrine markers and an increase in Hoxb4, which is normally expressed anterior to the pancreas. CONCLUSION: We conclude that beta-catenin expression is required for development of the exocrine pancreas, but is not required for development of the endocrine compartment. In contrast, beta-catenin/Wnt signaling appears to be critical for proliferation of PTF1+ nascent acinar cells and may also function, in part, to maintain an undifferentiated state in exocrine/acinar cell precursors. Finally, beta-catenin may be required to maintain positional identity of the pancreatic endoderm along the anterior-posterior axis. This data is consistent with the findings of frequent beta-catenin mutations in carcinomas of acinar cell lineage seen in humans.

Inhibition of Hedgehog signaling enhances delivery of chemotherapy in a mouse model of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDA) is among the most lethal human cancers in part because it is insensitive to many chemotherapeutic drugs. Studying a mouse model of PDA that is refractory to the clinically used drug gemcitabine, we found that the tumors in this model were poorly perfused and poorly vascularized, properties that are shared with human PDA. We tested whether the delivery and efficacy of gemcitabine in the mice could be improved by coadministration of IPI-926, a drug that depletes tumor-associated stromal tissue by inhibition of the Hedgehog cellular signaling pathway. The combination therapy produced a transient increase in intratumoral vascular density and intratumoral concentration of gemcitabine, leading to transient stabilization of disease. Thus, inefficient drug delivery may be an important contributor to chemoresistance in pancreatic cancer.