Search

Phenolic compounds (PC) are linked to astringency sensation. Astringency studies typically use simple models, with pure PC and/or proteins, far from what is likely to occur in the oral cavity. Different oral models have been developed here, comprising different oral epithelia (buccal mucosa (TR146) and tongue (HSC-3)) and other main oral constituents (human saliva and mucosal pellicle). These models, were used to study the interaction with two PC extracts, one rich in flavanols (a green tea extract) and one rich in anthocyanins (a red wine extract). It was observed that within a family of PC, the PC seem to have a similar binding to both TR146 and HSC-3 cell lines. When the oral constituents occur altogether, flavanols showed a higher interaction, driven by the salivary proteins. Conversely, anthocyanins showed a lower interaction when the oral constituents occur altogether, having a higher interaction only with oral cells. Epigallocatechin gallate, epicatechin gallate, epigallocatechin-3-O(3-O-methyl) gallate were the flavanols with the highest interaction. For the studied anthocyanins (delphinidin-3-glucoside, peonidin-3-glucoside, petunidin-3-glucoside and malvidin-3-glucoside), there was not a marked difference on their interaction ability. Overall, the results support that the different oral constituents can have a different function at different phases of food (PC) intake. These differences can be related to the perception of different astringency sub-qualities.

By light microscopy, the dysplastic oral epithelia due to the neoplastic processes are similar to epithelial changes due to the inflammatory processes. Scanning electron microscopy may elucidate the different surface changes between the two. The aim of this study was to examine the surface appearances of the dysplastic oral epithelia adjacent to oral squamous cell carcinoma to see if there are any surface changes. A total of 2 specimens, one specimen from each patient with oral squamous cell carcinoma, were used for this study. Each specimen was divided in two. One half was prepared for light microscopy and the other half was prepared for scanning electron microscopy. Light microscopically, the epithelia showed mild dysplasia. By scanning electron microscopy, the keratinized cells showed irregular microridges surrounding pits, which were variable and irregular in size and shape, and the nonkeratinized cells showed parallel microridges with irregularly widened intervals between each microridge. Irregular, broad, and partly swollen microridges and irregular short, stubby surface projections were also seen. The oral epithelia adjacent to oral squamous cell carcinoma showed mild dysplasia light microscopically but appeared abnormal by scanning electron microscopy. The abnormal epithelial cells showed pleomorphism, irregular and disoriented microridges, and abnormal surface microstructures.

The temperature of taste stimuli can modulate gustatory processing. Perceptual data indicate that the adapted temperature of oral epithelia also influences gustation, although little is known about the neural basis of this effect. Here, we electrophysiologically recorded orosensory responses (spikes) to 25°C (cool) and 35°C (warm) solutions of sucrose (0.1 and 0.3 M), NaCl (0.004, 0.1, and 0.3 M), and water from taste-sensitive neurons in the nucleus of the solitary tract in mice under varied thermal adaptation of oral epithelia. Conditions included presentation of taste stimuli isothermal to adaptation temperatures of 25°C (constant cooling) and 35°C (constant warming), delivery of 25°C stimuli following 35°C adaptation (relative cooling), and presentation of 35°C stimuli following 25°C adaptation (relative warming). Responses to sucrose in sucrose-oriented cells ( n = 15) were enhanced under the constant and relative warming conditions compared with constant cooling, where contiguous cooling across adaptation and stimulus periods induced the lowest and longest latency responses to sucrose. Yet compared with constant warming, cooling sucrose following warm adaptation (relative cooling) only marginally reduced activity to 0.1 M sucrose and did not alter responses to 0.3 M sucrose. Thus, warmth adaptation counteracted the attenuation in sucrose activity associated with stimulus cooling. Analysis of sodium-oriented ( n = 25) neurons revealed adaptation to cool water, and cooling taste solutions enhanced unit firing to 0.004 M (perithreshold) NaCl, whereas warmth adaptation and stimulus warming could facilitate activity to 0.3 M NaCl. The concentration dependence of this thermal effect may reflect a dual effect of temperature on the sodium reception mechanism that drives sodium-oriented cells.

To study cell kinetics of rat gingival (GE), sulcular (SE) and junctional (JE) epithelia in the steady-state and after application of mechanical pressure.Elastic bands were inserted between first and second maxillary molars of 8-week-old male rats, which were labelled with H(3) TdR and killed in groups of six to seven animals together with equal-sized groups of labelled control animals at intervals between 1 and 168 h. Autoradiographs were used to determine epithelial cell proliferation on the pressure side of M1 by calculating the percentage of (3)H TdR-labelled cells (PLC) in the basal (BL) and suprabasal (SL) layers of GE, SE and JE and to estimate median cell cycle (MCC) duration of BL cells by plotting mean and median grain counts against time.(3)H TdR-labelled cells were present in SL of SE and JE 1-12h after isotope injection suggesting that the BL might be not the only source of progenitor cells for JE as they might also be derived through migration from adjacent SE. Application of pressure significantly (ANOVA, P0.05) reduced PLC in BL of GE, SE and JE indicating a decrease of cell proliferation after 1-12h in response to pressure. In steady-state, the MCC durations of BL cells of GE, SE and JE were 39, 14 and 9h, respectively. After application of pressure, they increased significantly (chi(2)-test, P0.05) to 48, 44 and 34 h, respectively.Sustained pressure may lead to reduction of proliferative activity of these epithelia inducing slower progression of progenitor cells through the cell cycle.

The stratified squamous epithelium of the oral mucosa is characterized by significant regional variations mainly with regard to differences in the degree of keratinization. The oral mucosa is also divided into lining, masticatory, and specialized types reflecting the functions in different areas. The permeability barrier in the oral mucosa is mainly a result of membrane-coating granules composed of various lipids that differs between nonkeratinized and keratinized regions of the oral mucosa. Another feature of the environment of the oral cavity is saliva, which contains mucins that lubricate and protect the oral mucosa. Filaggrin is believed to function as a matrix protein supporting the aggregation of keratin filaments, and it has been demonstrated in especially keratinized oral mucosa like the palate. Filaggrin and its metabolites may contribute to difference in the functions and properties of the oral epithelia. Likewise, filaggrin gene (FLG) mutations and altered distribution of filaggrin/profilaggrin in oral mucosa may play a role in disorders affecting the oral epithelia, including oral contact allergy.

In humans, high concentrations of CO2, as found in carbonated beverages, evoke a mixture of sensations that include a stinging or pungent quality. The stinging sensation is thought to originate with the activation of nociceptors, which innervate the respiratory, nasal, and oral epithelia. The molecular basis for this sensation is unknown. Here we show that CO2 specifically activates a subpopulation of trigeminal neurons that express TRPA1, a mustard oil- and cinnamaldehyde-sensitive channel, and that these responses are dependent on a functional TRPA1 gene. TRPA1 is sufficient to mediate responses to CO2 as TRPA1 channels expressed in HEK-293 cells, but not TRPV1 channels, were activated by bath-applied CO2. CO2 can diffuse into cells and produce intracellular acidification, which could gate TRPA1 channels. Consistent with this mechanism, TRPA1 channels in excised patches were activated in a dose-dependent manner by intracellular protons. We conclude that TRPA1, by sensing intracellular acidification, constitutes an important component of the nociceptive response to CO2.

角化程度によるヒト口腔粘膜での上皮細胞表面糖鎖構造の発現変化を, レクチン組織化学的に検索した。粘膜の角化様式は, HE染色およびポーリー反応から,(a) 非角化,(b) 錯角化および (c) 正角化型に分類された。非角化および正角化型上皮では, 皮膚表皮と同様のレクチン結合性を上皮細胞は示した。しかしながら, 錯角化型では, PNA染色性が錯角化層の肥厚に伴い, 消失する傾向にあり, 過錯角化では完全に消失した。さらに同型上皮では, 表皮あるいは他の粘膜上皮において染色性を認めないDBAが, PNAの消失に伴い出現した。以上の結果は, 口腔粘膜上皮表面糖鎖構造の発現様式に角化程度が関与することを示し, 時にPNAとDBAの染色性の変化は, 錯角化形成過程の特徴的な現象であることが示唆された。

Covalently bound lipids have been identified and compared in keratinizing porcine epithelia including epidermis and oral epithelium from palate and gingiva. Stratum corneum was isolated by tryptic digestion, and after extensive extraction of lipids using a series of chloroform-methanol mixtures, the residual tissue was subjected to alkaline hydrolysis to release covalently bound lipids. The lipids so released were analyzed by quantitative thin-layer chromatography. Stratum corncum from each of the three anatomical sites contained ω-hydroxyceramides, ω-hydroxyacids and fatty acids. In epidermal stratum corneum the total covalently bound lipids represented 2.4% of the dry weight of the tissue, but in the oral epithelia this figure was consistently lower: 0.24% in palatal stratum corneum and 0.20% in gingival stratum corneum. Transmission electron microscopy before and after lipid extraction confirms the presence of a lipid envelope in epidermal stratum corneum and demonstrates the absence of this structure in oral stratum corneum.

Epithelial structural proteins, the keratins and keratin-associated proteins, are useful as markers of differentiation because their expression is both region-specific and differentiation-specific. In general, basal cells in all stratified oral epithelia express similar keratins, while the suprabasal cells express a specific set of markers indicating commitment to a distinct program of differentiation. Critical factors in the regulation of epithelial protein expression are now under investigation. The promoter regions of keratin genes are being characterized to determine what sequences within the genes are responsible for differential expression. One important extracellular factor that influences epithelial protein expression is retinol (vitamin A), which exerts its effects via a group of nuclear receptor proteins that may also be expressed in a region-specific manner. These molecular biological approaches enhance our understanding of the mechanisms regulating differentiation of oral epithelia and its regional complexity.

The permeability of skin and oral mucosa to various compounds has been measured but the actual pathways substances take in traversing the epithelia have not been identified. In this study, radiolabelled cholesterol, ethanol or water were placed on the surface of porcine skin, keratinized gingiva, or nonkeratinized floor of mouth mucosa, and incubated at 37 degrees C for 2 h. The tissue was then snap-frozen, and sectioned in a cryostat, picked up on precoated slides and exposed at -20 degrees C for 40 days for light microscopic autoradiography. Some tissues were freeze-dried and directly embedded in low viscosity resin and prepared for electron microscopic autoradiography. Examination of autoradiographs revealed silver grains over, or adjacent to, intercellular spaces. Counts of the grains over the extra- and intracellular compartments were made in random light and electron microscope fields. For all compounds and tissue regions, there were significantly more (p less than 0.05) grains over the intercellular spaces than over the cells. The results indicate that the intercellular compartment is the predominant route for compounds moving across the superficial barrier layer of epidermis and oral epithelia. The nature of the intercellular material is, thus, a primary determinant of epithelial permeability.

A system has been developed for examining connective tissue influence on keratinization of normal and leukoplakic human oral epithelia. Paired biopsy specimens of normal and leukoplakic mucosa were left intact or were incubated in 1 mM EDTA to permit epithelial-connective tissue separation and various recombinations of the epithelium and connective tissue. The tissues were transplanting to subdermal sites of "nude" (nu/nu) mice and were protected by polyethylene capsules. 44% of implants performed were recovered apparently vital. Preexisting structure was retained after epithelial-connective tissue separation and self-recombination. Cross-recombined specimens showed changes in patterns of keratinization including changes of keratinized leukoplakic epithelium to a non-keratinized type.

Male rats in four different age groups of 2, 9, 19 and 27 months were injected with tritiated thymidine and sacrificed 45 min later. Autoradiographic sections from the palatal and the lingual epithelia were studied. The number of basal cells per mm of length, the number of labeled cells in the basal layer, and in the suprabasal area, were counted. It was found that the progenitor cell population was not limited to the basal layer alone. Thus, the number of basal cells did not coincide with the number of progenitor cells. This study deals with changes in the oral epithelia of the rat at two age periods. One, between 2 and 9 months, is a decrease of the synthesis index while the progenitor size stays constant associated with a change from a rapid growing animal to a mature one. The second, between 9 and 27 months, is a decrease in the progenitor population and an increase in the synthesis index.

Lipid compositions have been determined by quantitative thin-layer chromatography for epidermis, floor of mouth, gingiva, palate and buccal epithelium of the pig (Sus scrofa). All of the epithelia contained phospholipids, glycosylceramides, cholesteryl sulfate, cholesteryl esters, free sterols, fatty acids and triglycerides. Epidermis, palate and gingiva had similar lipid compositions, which were characterized by the presence of O-acylglycosylceramides, O-acylceramides and relatively high proportions of ceramides. Floor of mouth and buccal epithelium, which are not keratinized, contained no O-acylglucosylceramides or O-acylceramides and very little ceramide. The higher water permeability of the non-keratinized oral regions may reflect the absence of acylglucosylceramides and the low proportions of ceramides.

Epithelial sheets prepared from murine oral epithelia (palate, lining mucosa, gingiva) and oesophagus contained dendritic and round Thy-1 positive (+) cells similar to those observed in epidermis by immunofluorescence microscopy. Bladder, intestine and tracheal epithelium did not contain such cells. Thus, cells bearing the cells-surface glycoprotein Thy-1, like 1a-antigen-bearing Langerhans cells, may be restricted to stratified squamous epithelia.

Possible changes in the structure of human oral mucosa resulting from exposure to chlorhexidine were examined in biopsy specimens of palatal and gingival mucosa obtained from three groups of young adults who had rinsed for more than 1 year (a) once or (b) twice daily with 0.2 % chlorhexidine solution or (c) with a placebo mouthwash. Specimens were quenched in liquid nitrogen and cryostat sectioned perpendicular to the epithelial surface. Sections stained with hematoxylin and eosin were used to assess the degree of keratinization of epithelia and to measure the width of the stratum corneum. Sections treated with buffered alkaline solutions were used to expand and count the number of layers of cells in the stratum corneum. All specimens examined showed evidence of keratinization and, in keeping with previous reports, palatal specimens were more frequently orthokeratinized than gingival specimens. Mean width of the stratum corneum of gingival specimens was approximately 13 μm and of palatal specimens, 23 μm. The mean number of layers of cells in the stratum corneum of the gingiva was approximately 10 and of the palate, approximately 12. Differences in the degree of keratinization and thickness of the stratum corneum between gingival and palatal specimens was statistically significant, but no statistically significant differences were found between the chlorhexidine-exposed and non-chlorhexidine-exposed palatal tissue in keratinization, layers of cells or thickness of the stratum corneum. Neither was there any statistical difference in the same parameters for the gingival specimens. The methods employed did not therefore detect any changes in the normal structure of keratinizing oral epithelia as a result of prolonged daily exposure to chlorhexidine.

A histochemical comparison was made of the demonstration of polysaccharides in dental germs and oral epithelia after a treatment with acid containing alcoholic decalcifying solutions. Decalcifying solutions were prepared with 5% acids (HCL, HCOOH, HNO3, trichloracetic acid, ethylendiamin tetracetate) in a 30 or 50% alcohol solution.1. The oral epithelium of fetal animals showed a large amount of glycogen. Glycogen of the fetal oral epithelium showed a good preservation after a treatment with acid containing alcoholic decalcifying solutions (except for the case of trichloracetic acid). No differences in the appearance of glycogen in the oral epithelium were observed between 30% and 50% alcohol decalcifying solutions.2. Nuclear staining was observed by the periodic acid-SCHIFF reaction after a treatment with acid containing decalcifying solutions. The use of HCL, HNO3, trichloracetic acid in decalcification resulted staining of the nucleus in various intensities.3. The treatment with acid containing alcohol decalcifying agents without ethylendiamin tetracetate resulted in the decalcification of the jaws of fetal dogs and rats, but almost no-decalcification in the knee joints of 4 day to 4 week post natal rats.4. The presence of glycogen in the developing tooth germs was rather low in comparison with the oral epithelium which was abundant in glycogen. The distribution patterns of glycogen in dental germ were the same as in the previous reports.

Grams of dry weight per cm3 of tissue (DRD) were determined on the successive histologic layers of rat buccal and palatal mucosa, both of which form thick layers of orthokeratin. The experimental animals were six young adult male albinos of Simonsen strain. Microdissection was used for isolation of tissue fragments from frozendashdried sections, a quartz fibre balance (according to Lowry) for weighing and a split-image microscope for measuring the dimensions of the fragments. The density of basal cells in both tissues was 0.26g/cm3 and both showed a rise of 12 per cent between basal and lower spinous cells. Succeeding layers of the palate showed a continuous rise, those of cheek a continuous decline. The greatest change in both tissues occurred between granular and keratin layer. Palatal keratin had a density of 0.63g/cm3, buccal keratin of 0.21g/cm3. Sample variability was 9–12 per cent of the average per layer per animal and greatest in cheek keratin. Individual variability was 2–6 per cent of the average for six animals. Taking changes in cell size into account, it was concluded that loss of water occurs between granular and keratin layers of the palate, but uptake of water between deeper and superficial keratin cells of the cheek. Different regions of oral orthokeratin thus showed opposite responses to their common fluid environment.