Keratin pattern in human oral buccal and hard palate mucosa

Abstract – As a preliminary study the keratin proteins of human oral stratified epithelia from buccal mucosa and hard palate were investigated using SDS-PAGE technique. The keratinized hard palate consistently showed six polypeptides varying in molecular weight from 47 to 67 k daltons, whereas the nonkeratinized buccal epithelium lacked the larger polypeptides and showed three polypeptides with molecular weight from 50 to 56 k daltons. The individual variations in the SDS-gel pattern from eight clinically normal individuals were restricted to minor quantitative differences.     

Comparative permeability of various chemical markers through human vaginal and buccal mucosa as well as porcine buccal and mouth floor mucosa

A number of drugs undergo extensive first-pass metabolism after oral administration, necessitating large doses for effective therapeutic responses in the body. Buccal administration of drugs is becoming more popular because the drugs diffuse into the systemic circulation directly, circumventing the first-pass metabolism. Lower concentrations thus need to be administered and side effects may be minimized. In this study, one of the classic models for human buccal permeability, i.e. the porcine buccal mucosal model, is compared with the more recent human vaginal model and both these are in turn further compared to porcine mouth floor mucosa. To determine the permeability of the different markers (arecoline, 17beta-estradiol, water and vasopressin), a continuous flow-through perfusion system was used (20 degrees C, 24h). Mean steady state flux values were compared statistically using a t-test at a significance level of 5%. Porcine buccal mucosa showed a consistently lower permeability towards all the markers than the other mucosae tested. Porcine mouth floor mucosa was found to be more permeable than porcine buccal mucosa. From these studies we concluded that human vaginal and porcine mouth floor mucosae were superior models for human buccal mucosa than porcine buccal mucosa, using in vitro permeability studies with various chemical markers.     

Ultrastructural investigation of hard palate mucosa under complete dentures

An ultrastructural investigation was made to study the tissue changes occurring under complete dentures. Biopsy from 45 patient specimens were obtained from lesions of hard palate mucosa. Narrow intercellular space with less distinct bridges, loosely knit arrangement of tonofilaments, prominent endoplasmic reticulum, and vacuolar conformation of mitochondria were observed in the cells of epithelium. The underlying connective tissue was characterized by a preponderance of newly formed collagen fibers and numerous fibroblasts. Macrophages were located in the lamina propria and perivascular regions. Lymphocytes, neutrophils, and plasma cells were seen in moderate numbers. These cells, when present in clusters, should be considered as a component of the defense system.     

Langerhans cell surface densities in rat oral mucosa and human buccal mucosa

We determined surface densities of Langerhans cells (LCs) in rat oral mucosa and human buccal mucosa by enumerating ATPase-positive dendritic cells in epithelial whole mounts. For the rat, mean surface densities per mm² were 160 in anterior buccal mucosa, 640 in posterior buccal mucosa, 430 in the palate and 340 in the tongue. Human buccal mucosa showed a density of 890 cells per mm². We conclude that LC densities in oral mucosa approximate those of external body sites, making them available in numbers sufficient to accomplish their postulated antigen-presenting functions.     

Langerhans cell surface densities in rat oral mucosa and human buccal mucosa

We determined surface densities of Langerhans cells (LCs) in rat oral mucosa and human buccal mucosa by enumerating ATPase-positive dendritic cells in epithelial whole mounts. For the rat, mean surface densities per mm2 were 160 in anterior buccal mucosa, 640 in posterior buccal mucosa, 430 in the palate and 340 in the tongue. Human buccal mucosa showed a density of 890 cells per mm2. We conclude that LC densities in oral mucosa approximate those of external body sites, making them available in numbers sufficient to accomplish their postulated antigen-presenting functions.     

Identification of epidermal growth factor receptor in human buccal mucosa

EGF receptor was identified and its binding characteristics were determined. Buccal mucosa was obtained from 12 healthy volunteers (6 males and 6 females) and assayed individually for [125I]-EGF binding. The specific binding of [125I]-EGF to the receptor ranged from 2.85 to 6.12 fmol/mg protein. There was no significant difference in binding between male and female (4.31 +/- 0.61 versus 3.94 +/- 0.53 fmol/mg protein; mean +/- SEM). Individual tissue homogenates were pooled for Scatchard analysis and cross-linking experiments. Scatchard analysis produced curvilinear plots with a Kd of 0.71 nM and Bmax of 0.024 pmol/mg protein for the high-affinity binding sites, and Kd of 435 nM and Bmax of 9.92 pmol/mg protein for the low-affinity binding sites. To determine the molecular weight of the EGF receptor, the [125I]-EGF and receptor complex were cross-linked by DSS and subjected to SDS-PAGE. The autoradiogram of the gel revealed one major protein band of 160K and a minor band of 170 K, characteristics shared with the EGF receptors in other tissues. The study is thought to be the first to demonstrate the presence of the EGF receptor in human buccal tissue and to show its biochemical features.     

Comparative permeability of human vaginal and buccal mucosa to water

There is currently a resurgence of interest in the oral mucosa as a route for drug delivery. The relative scarcity of human oral mucosa for in vitro permeability studies, and the fact that vaginal mucosa is histologically similar and more abundant than the former, caused us to compare these 2 tissues with respect to their barrier properties to water. Specimens of fresh, clinically-healthy human vaginal and buccal mucosa from non-smokers were taken from excised tissue obtained during vaginal hysterectomies and various oral surgical procedures. Biopsies from each specimen were mounted in flow-through diffusion cells and their permeability to tritiated water determined using a continuous flow-through perfusion system. Specimens were examined histologically before and after permeability experiments and similarities between vaginal and buccal tissues verified. No statistically significant differences between mean steady state flux values (10–16 h) for vaginal and buccal mucosa. respectively, were found. Human vaginal mucosa is therefore as permeable as buccal mucosa to water, and these results warrant further investigation with other compounds to establish whether vaginal mucosa may be a useful model for buccal mucosa for drug permeability studies.     

Epithelial outgrowths from human buccal mucosa transplants in nude mice

Abstract – The histologic features of epithelial outgrowths from transplants of human buccal mucosa in nude mice are described. Ninety-six samples of normal buccal mucosa were transplanted to subcutaneous sites in the flank region of nude mice. The tissue specimens were maintained in the mice for periods ranging from 1 to 67 d and were protected from overlying murine cutaneous and subcutaneous tissue by polyethylene capsules or by Millipore® filters. The epithelial outgrowths from the transplants were formed over murine connective tissue, with and without substantial infiltrate of neutrophils, and over Millipore filter with and without interjacent murine connective tissue. The stratified: squamous epithelium was essentially unkeratinized and thinner than that overlying originally transplanted connective tissue. The histologic features of the outgrowths were similar irrespective of the technique used or the type of underlying tissue.     

Smooth-surfaced, nonpainful swelling in the buccal mucosa

A typical example of irritation fibrosis arising in the buccal mucosa has been presented. Clinicians are cautioned that although this common oral lesion generally appears clinically in a fairly characteristic manner, to rule out a more serious, similar appearing disease, these lesions should be surgically excised and examined microscopically.     

Distribution of glands in the mucosa of the hard palate and its relation to carcinoma.

Carcinoma of the hard palate in women who practice reverse smoking is very common in Visakhapatnam. This carcinoma usually occurs in the middle of the posterior half of the hard palate and not in the soft palate or in the anterior half of hard palate. The volume of the glandular tissue in the mucosa of the hard palate is maximum to the right or left half of the midline in the posterior half in both fetuses and adults. The localization of the carcinoma of the hard palate in reverse smokers corresponds to the glandular area of the mucosa of the hard palate.     

Toxic effects of two dental materials on human buccal epithelium in vitro and monkey buccal mucosa in vivo

Confluent cultures of human buccal epithelial cells were exposed to graded dilutions of Gluma Bond or 3M Etching Liquid for 5 min. The cytotoxic effects induced by this treatment were observed (epithelial cell damage, growth inhibition). In vivo, monkey buccal mucosa was exposed to Gluma Bond or 3M Etching Liquid for 5 min. Biopsies were taken after 24 h, and the buccal epithelium processed for light microscopic examination. The toxic reactions to Gluma Bond were far more pronounced compared with the toxic reactions to 3M Etching Liquid in both models. Data obtained suggest that the in vitro model may be useful in assessing mucosal toxicity and in studying mechanisms of toxic action.     

Toxic effects of two dental materials on human buccal epithelium in vitro and monkey buccal mucosa in vivo

Abstract – Confluent cultures of human buccal epithelial cells were exposed to graded dilutions of Gluma Bond or 3M Etching Liquid for 5 min. The cytotoxic effects induced by this treatment were observed (epithelial cell damage, growth inhibition). In vivo, monkey buccal mucosa was exposed to Gluma Bond or 3M Etching Liquid for 5 niin. Biopsies were taken after 24 h, and the buccal epithelium processed for light microscopic examination. The toxic reactions to Gluma Bond were far more pronounced compared with the toxic reactions to 3M Etching Liquid in both models. Data obtained suggest that the in vitro model may be useful in assessing mucosal toxicity and in studying mechanisms of toxic action.     

Stimulation of human buccal mucosa fibroblasts in vitro by betel-nut alkaloids

Oral submucous fibrosis (OSF) is characterized by excessive collagen production by mucosal fibroblasts and is associated with the habitual chewing of betel-nuts (Areca catechu); nut extracts stimulate fibroblast activity in vitro. The metabolism of arecoline, the major alkaloid in the nut, by human buccal mucosa fibroblasts in vitro was investigated; alkaloid metabolites extracted from culture media were analysed by gas chromatography and thin-layer chromatography. [3H]-arecoline was metabolized predominantly to [3H]-arecaidine and this was accompanied by a concentration-dependent stimulation of collagen synthesis and cell proliferation. Arecaidine was a more potent stimulator than arecoline. The rate of hydrolysis of a series of synthetic arecaidine esters (methyl, ethyl, butyl, propyl and pentyl) by fibroblasts was closely correlated with the extent of stimulation of collagen synthesis. Thus fibroblasts are responsive to the major metabolite of arecoline and hydrolysis of the ester group may be necessary for this action. Exposure of buccal mucosa fibroblasts to these alkaloids in vivo may contribute to the accumulation of collagen in OSF.     

Diffusion of reduced arecoline and arecaidine through human vaginal and buccal mucosa

Because alkaloids from areca nut, arecoline and arecaidine, have been implicated in the development of oral submucous fibrosis, we determined their diffusion kinetics through human buccal and vaginal mucosa. Four clinically healthy vaginal mucosa specimens (mean patient age +/- standard deviation: 47 +/- 15 years; age range: 31-60 years) and 4 buccal mucosa specimens from 2 male patients and 2 female patients (mean patient age +/- standard deviation: 31 +/- 9 years; age range: 17-53 years) were obtained during surgery. In vitro flux rates of reduced arecoline and arecaidine (r-arecoline and r-arecaidine) were determined by use of a flow-through diffusion apparatus. Analysis of variance, a Duncan multiple range test, and an unpaired t-test were used to determine steady state kinetics and flux differences over time intervals. Although statistically significant differences were observed between flux values for both alkaloids and tissues at certain time points, these were not considered to be of biological (clinical) significance. However, the flux rates across both mucosa of r-arecoline were significantly higher statistically than those of rarecaidine. The findings demonstrated the differences in the diffusion kinetics between r-arecoline and r-arecaidine across human buccal and vaginal mucosa, an observation that could be explained in terms of their ionisation characteristics. Additionally, the results obtained further support the hypothesis that human vaginal mucosa can be used as a model for buccal mucosa in studies of permeability to various chemical compounds.