Faculty Bibliography

BACKGROUND: Amphipathic sweet and bitter tastants inhibit purified forms of the protein kinases GRK2, GRK5 and PKA activities. Here we tested whether membrane-permeable tastants may intracellularly interfere with GPCR desensitization at the whole cell context. METHODS: 2AR-transfected cells and cells containing endogenous 2AR were preincubated with membrane-permeable or impermeable tastants and then stimulated with isoproterenol (ISO). cAMP formation, 2AR phosphorylation and 2AR internalization were monitored in response to ISO stimulation. IBMX and H89 inhibitors and GRK2 silencing were used to explore possible roles of PDE, PKA, and GRK2 in the tastants-mediated amplification of cAMP formation and the tastant delay of 2AR phosphorylation and internalization. RESULTS: Membrane-permeable but not impermeable tastants amplified the ISO-stimulated cAMP formation in a concentration- and time-dependent manner. Without ISO stimulation, amphipathic tastants, except caffeine, had no effect on cAMP formation. The amplification of ISO-stimulated cAMP formation by the amphipathic tastants was not affected by PDE and PKA activities, but was completely abolished by GRK2 silencing. Amphipathic tastants delayed the ISO-induced GRK-mediated phosphorylation of 2ARs and GRK2 silencing abolished it. Further, tastants also delayed the ISO-stimulated 2AR internalization. CONCLUSION: Amphipathic tastants significantly amplify 2AR signalling and delay its desensitization via their intracellular inhibition of GRK2. GENERAL SIGNIFICANCE: Commonly used amphipathic tastants may potentially affect similar GPCR pathways whose desensitization depends on GRK2's kinase activity. Because GRK2 also modulates phosphorylation of non-receptor components in multiple cellular pathways, these gut-absorbable tastants may permeate into various cells, and potentially affect GRK2-dependent phosphorylation processes in these cells as well.

In 2005, New York University Colleges of Dentistry and Nursing formed an organizational partnership to create a unique model of interprofessional education, research, service and practice. This paper describes the first eight years of experience, from the early reaction of the public to the partnership, to examples of success and past and current challenges.

Beginning in 2012, candidate performance on the National Board Dental Examination (NBDE) has been reported as pass/fail, and only the failing candidates receive numerical scores for remediation purposes. The Joint Commission on National Dental Examinations recognizes that the numerical scores have been important information to dental schools for curriculum evaluation and that the pass/fail reports do not provide meaningful information to the schools. This article describes the process of evaluating and validating a new model for reporting standardized school-level performance data on the NBDE. Under this new model, schools are able to monitor the overall performance of their students compared to a national cohort.

BACKGROUND: Alleles of the receptor gene TAS2R38 are responsible in part for the variation in bitter taste perception of 6-n-propylthiouracil (PROP) and structurally similar compounds (eg, glucosinolates in cruciferous vegetables). At low concentrations, people with the PAV ("taster" amino acid sequence) form of TAS2R38 perceive these bitter compounds, whereas most with the AVI ("nontaster" amino acid sequence) form do not; heterozygotes (PAV/AVI) show the widest range of bitter perception. OBJECTIVES: The objectives were to examine individual differences in expression of PAV-TAS2R38 messenger RNA (mRNA) among heterozygotes, to test the hypotheses that the abundance of allele-specific gene expression accounts for the variation in human bitter taste perception, and to relate to dietary intake of bitter-tasting beverages and foods. DESIGN: Heterozygous individuals (n = 22) provided psychophysical evaluation of the bitterness of PROP, glucosinolate-containing broccoli juice, non-glucosinolate-containing carrot juice, and several bitter non-TAS2R38 ligands as well as dietary recalls. Fungiform taste papillae were examined for allele-specific TAS2R38 expression by using quantitative polymerase chain reaction. RESULTS: PAV-TAS2R38 mRNA expression was measured in 18 of 22 heterozygous subjects. Relative expression varied widely and positively correlated with ratings of bitterness intensity of PROP (P = 0.007) and broccoli juice (P = 0.004) but not of the control solutions carrot juice (P = 0.26), NaCl (P = 0.68), caffeine (P = 0.24), or urea (P = 0.47). Expression amounts were related to self-reported recent and habitual caffeine intake (P = 0.060, P = 0.005); vegetable intake was too low to analyze. CONCLUSIONS: We provide evidence that PAV-TAS2R38 expression amount correlates with individual differences in bitter sensory perception and diet. The nature of this correlation calls for additional research on the molecular mechanisms associated with some individual differences in taste perception and food intake. The trial was registered at clinicaltrials.gov as NCT01399944.

The famous Iceman 'Otzi' (South Tyrol Museum of Archaeology, Bolzano, Italy), a Neolithic human ice mummy, offers a unique opportunity to study evolutionary aspects of oral disease. The aim of this study was to assess, for the very first time, his oral cavity, which surprisingly had never been examined systematically. Based on several computed tomography (CT) scans from 1991 onwards and on macroscopic investigation, only a few findings, such as a central maxillary diastema, heavy abrasions, and missing wisdom teeth, were known. We re-evaluated the latest CT scans from 2005 and found various oral pathologies. In line with the increase of tooth decay in the Neolithic - because of diet change in this historic transition phase - several carious lesions were found, one of which penetrated into the dental pulp. In accordance with the Iceman's troubled life, as several injuries on his body and his violent death attest, mechanical trauma of one of his upper front teeth is evident. Finally, the poor periodontal condition of the Iceman's dentition (e.g. loss of alveolar bone), indicative of periodontitis, was assessed. These oral pathological findings in the Iceman's dentition provide a unique glimpse into the evolutionary history of oral conditions.

Taste cells are highly specialized, with unique histological, molecular and physiological characteristics that permit detection of a wide range of simple stimuli and complex chemical molecules contained in foods. In human, individual fungiform papillae contain from zero to as many as 20 taste buds. There is no established protocol for culturing human taste cells, although the ability to maintain taste papillae cells in culture for multiple cell cycles would be of considerable utility for characterizing the molecular, regenerative, and functional properties of these unique sensory cells. Earlier studies of taste cells have been done using freshly isolated cells in primary culture, explant cultures from rodents, or semi-intact taste buds in tissue slices. Although each of these preparations has advantages, the development of long-term cultures would have provided significant benefits, particularly for studies of taste cell proliferation and differentiation. Several groups, including ours, have been interested in the development and establishment of taste cell culture models. Most attempts to culture taste cells have reported limited viability, with cells typically not lasting beyond 3-5 d. We recently reported on a successful method for the extended culture of rodent taste cells. We here report for the first time the establishment of an in vitro culture system for isolated human fungiform taste papillae cells. Cells from human fungiform papillae obtained by biopsy were successfully maintained in culture for more than eight passages (12 months) without loss of viability. Cells displayed many molecular and physiological features characteristic of mature taste cells. Gustducin and phospholipase C beta2, (PLC-beta2) mRNA were detected in many cells by reverse transcriptase-polymerase chain reaction and confirmed by sequencing. Immunocytochemistry analysis demonstrated the presence of gustducin and PLC-beta2 expression in cultured taste cells. Cultured human fungiform cells also exhibited increases in intracellular calcium in response to appropriate concentrations of several taste stimuli indicating that taste receptors and at least some of the signalling pathways were present. These results sufficient indicate that taste cells from adult humans can be generated and maintained for at least eight passages. Many of the cells retain physiological and biochemical characteristics of acutely isolated cells from the adult taste epithelium to support their use as a model taste system. This system will enable further studies of the processes involved in proliferation, differentiation and function of mammalian taste receptor cells in an in vitro preparation. Human fungiform taste papillae used for establishing human fungiform cell culture were donated for research following proper informed consent under research protocols that were reviewed and approved by the IRB committee. The protocol (#0934) was approved by Schulman Associates Institutional Review Board Inc., Cincinnati, OH. Written protocol below is based on published parameters reported by Ozdener et al. 2011.

The ability to maintain human fungiform papillae cells in culture for multiple cell cycles would be of considerable utility for characterizing the molecular, regenerative, and functional properties of these unique sensory cells. Here we describe a method for enzymatically isolating human cells from fungiform papillae obtained by biopsy and maintaining them in culture for more than 7 passages (7 months) without loss of viability and while retaining many of the functional properties of acutely isolated taste cells. Cells in these cultures exhibited increases in intracellular calcium when stimulated with perceptually appropriate concentrations of several taste stimuli, indicating that at least some of the native signaling pathways were present. This system can provide a useful model for molecular studies of the proliferation, differentiation, and physiological function of human fungiform papillae cells

This study compared the anatomical features of the tongue in nine pairs of twins - six monozygotic and three dizygotic. The aim of the project was to determine if tongues, like any other anatomical structure, could be used to reliably predict relatedness given that tongue shape, presentation and surface can be influenced by environment. Using the method of forced choice, 30 subjects were asked to match the photographs of tongues from twins. Our data indicate that, based on visual assessment, monozygotic twins have highly similar tongues (60% matches); similarly, dizygotic twins were matched 31% of the time, which is a higher probability than would be expected from random selection. This study should help identify baseline and control data in future behavioral studies of taste, which has a genetic basis

The sense of taste is critical for human life. It informs the body about the quality of food that will be potentially ingested and stimulates metabolic processes that prepare the alimentary canal for digestion. Steady progress is being made towards understanding the early biochemical and molecular events underlying taste transduction (for a review, Breslin and Spector, 2008). However, progress to date has largely resulted from animal models. Yet, since marked differences in receptor specificity and receptor density vary among species, human taste transduction will only be understood by using human taste tissue. Here we describe a biopsy technique to collect human fungiform papillae, visible as rounded pink anterior structures, about 0.5 mm in diameter that contain taste buds. These biopsied papillae are used for several purposes including the isolation of viable taste bud cells, in situ hybridization, immunohistochemistry and, through techniques of molecular biology, the identification of taste-specific novel proteins