[The glands of the dorso-distal mucosa of the toad Bufo marinus (Amphibia: Anura) tongue: histology and ultrastructure ]

Frequently, the studies on the lingual epithelium ultrastructure in anurans do not show differences between filiform papilae and glandular epithelia in the non-sensory dorsal epithelium. To accomplish the study of glandular epithelium, samples of dorso-distalis mucosae of Bufo marinus tongue were processed for transmission electron microscopy and also semithin sections of the same material were used for light microscopy study. The results showed that the glandular epithelium is constituted by three different types of cells: (1) serous granular secretory cells; (2) mitochondria rich cells (CRM); and (3) ciliated cells. Detailed structures of each type of cell under light and electron microscopy were given. Notably, in the lingual portion studied, secretory cells showed no signs of exocytosis of their granules, thus suggesting that they do not have a basal or continuous rate of secretory activity. Additionally, the distribution, localization and structure of CRM in the gland epithelium suggest their participation in secretory cell maturation and/or function.

[Cytogenetic testing in evaluation of the ecological situation and the effect of natural adaptogens on children and adult health]

The use of cytogenetic testing on the micronuclear test in cells of the population of children is substantiated for the estimation of mutagenicity of the territory on which they live. The positive modifying cytogenetic influence of natural adaptogens on improvement of health of organisms injured by adverse factors is established.

Subcellular localization of beta-catenin in malignant cell lines and squamous cell carcinomas of the oral cavity

BACKGROUND

Beta-catenin, an E-cadherin-associated protein involved in cell-cell adhesion and signaling, has been hypothesized to translocate to the nucleus and activate transcription in several human cancers, including oral squamous cell carcinomas (OSCC).

METHODS

In the present study, we analyzed the subcellular localization of beta-catenin in cultures of human oral normal and malignant (cell lines SCC15 and SCC25) keratinocytes and in 24 frozen samples of oral squamous cell carcinomas by a double-staining technique for nucleic acids and beta-catenin. Growth potential, as assessed by cell count at different time periods, was established for normal, SCC15 and SCC25 cell lines; oral squamous cell carcinomas were classified according to the histopathological and malignancy indexes.

RESULTS

Beta-catenin localized at the plasma membrane in the normal and SCC15 cells, not in the SCC25 cells, where it localized mostly in the perinuclear and nuclear areas. In the growth assays, SCC25 cell lines proliferated faster than in normal and SCC15 cells over a period of 6 days (cell numbers were significantly different, P < 0.0001). Carcinoma sections showed a combination of membranous, cytoplasmic and, in few invading epithelial islands of two tumors, nuclear localization of beta-catenin.

CONCLUSIONS

In oral squamous cell carcinomas, nuclear beta-catenin staining was observed only within invading islands of two carcinomas deep in the underlying connective tissue. On the basis of this study, we conclude that intranuclear beta-catenin does not appear to be a common finding in oral squamous cell carcinomas and that a clear association between intranuclear beta-catenin and histopathological and malignancy indexes in vivo could not be established.

Angioarchitectural characteristics of the anterodorsal surface of aging and young rabbit tongue: scanning electron microscopy study

The three-dimensional angioarchitecture of young and aging rabbit tongues were studied using a vascular corrosion cast method. The vascular network of different lingual papillae were observed by scanning electron microscope (SEM). Young animals showed filiform papillae distributed all over considered area, with fungiform ones among them. In comparison to developed specimens, young rabbits demonstrated dense and higher organization of microvascular network.

Ultrastructural study of the cheek oral mucosa of rats submitted to experimental chronic alcoholism

Ultrastructural features of the cheek oral mucosa of rats (Rattus norvegicus) submitted to experimental chronic alcoholism were studied by transmission electron microscopy. Sixty male rats aged three months and with a mean body weight of 250 g were divided into two experimental groups. The control group received a solid diet (Purina rat chow) and tap water ad libitum. The alcoholic group received the same solid diet but was only allowed to drink sugar cane liquor dissolved in 30 degrees Gay Lussac (v/v). The animals of the two groups were weighed and sacrificed after 60, 120, and 180 days of treatment. Samples of the oral mucosa from the cheek region were dissected and processed for ultrastructural analysis. The results showed cell alterations in the basal and intermediate layer of the mucosal epithelium. The most frequent alterations observed were an increased intercellular space, the presence of lipid droplets in the cytoplasm, and irregular nuclei with a pyknotic aspect.

Ultrastructural changes in malignant transformation of oral mucosa

Transmission electron microscopy (EM) has been used to identify the ultrastructural details of normal and cancerous human oral mucosa. However, inconsistent reports of structural descriptions have rendered transmission EM valueless in the diagnosis of oral squamous cell carcinoma (SCC) or as a prognostic indicator. To identify features of dysplasia for diagnostic purposes, normal mucosa, severe dysplasia, oral SCC and normal margin adjacent to oral SCC were used to compare the ultrastructural features of normal and premalignant oral mucosa and oral SCC. The preparatory stages of dehydration, embedding, cutting and positive staining for transmission EM were modified and tested to improve ultrastructural definition. Thin and discontinuous basal laminas were found in mucosa with severe dysplasia and normal margin adjacent to oral SCC. No basal lamina was identified in oral SCC. This study has shown that there are some ultrastructural changes during malignant transformation of oral mucosa. Together with other laboratory investigative techniques, transmission EM may be helpful in detecting malignant changes in oral mucosa.

Cytogenetic analysis of buccal cells from shoe-workers and pathology and anatomy laboratory workers exposed to n-hexane, toluene, methyl ethyl ketone and formaldehyde

People employed in the shoe manufacture and repair industry are at an increased risk for cancer, the strongest evidence being for nasal cancer and leukaemia. A possible causal role for formaldehyde is likely for cancer of the buccal cavity and nasopharynx. Exfoliated buccal cells are good source of tissue for monitoring human exposure to inhaled and ingested occupational and environmental genotoxicants. To assess the cytogenetic damage related to occupational exposure to airborne chemicals during shoe-making and the processes in pathology and anatomy laboratories, the micronuclei (MN) count per 3000 cells was measured in buccal smears from shoe-workers (group I, n = 22) exposed to mainly n-hexane, toluene and methyl ethyl ketone (MEK) and from anatomy and pathology staff (group II, n = 28) exposed to formaldehyde (FA). Eighteen male university staff were used as controls. The mean time-weighted average (TWA) concentrations of n-hexane, toluene and MEK in 10 small shoe workshops were 58.07 p.p.m., 26.62 p.p.m. and 11.39 p.p.m., respectively. The measured air concentrations of FA in the breathing zone of the anatomy and pathology laboratory workers were between 2 and 4 p.p.m. Levels of 2,5-hexadione (2,5-HD) and hippuric acid (HA), metabolic markers of n-hexane and toluene exposure, respectively, were significantly higher in the urine of workers in group I than in control subjects (p < 0.001 and p < 0.01, respectively). The mean (+/- SD) MN (0/00) [corrected] frequencies in buccal mucosa cells from workers in group I, group II and controls were 0.62 +/- 0.45%, 0.71 +/- 0.56% and 0.33 +/- 0.30%, respectively (p < 0.05 and p < 0.05 compared with controls for group I and group II, respectively). The effects of smoking, age and duration of exposure on the frequency of micronucleated buccal cells from workers in all three groups studied were also evaluated. Overall, the results suggest that occupational exposure to organic solvents, mainly n-hexane, toluene, MEK and FA, may cause cytogenetic damage in buccal cells and that use of exfoliated buccal cells seems to be appropriate to measure exposure to organic solvents.

Olfactory mucosal necrosis in male CD rats following acute inhalation exposure to hydrogen sulfide: reversibility and the possible role of regional metabolism

Hydrogen sulfide (H2S) is a potent inhibitor of cytochrome oxidase (CO) and is associated with dysosmia and anosmia in humans and nasal lesions in exposed rodents. An improved understanding of the pathogenesis of these lesions is needed to determine their toxicological relevance. We exposed 10-week-old male CD rats to 0, 30, 80, 200, or 400 ppm H2S for 3 hours/day for 1 or 5 days consecutively. The nose was histologically examined 24 hours after H2S exposure, and lesion recovery was assessed at 2 and 6 weeks following the 5-day exposure. A single 3-hour exposure to > or = 80 ppm H2S resulted in regeneration of the respiratory mucosa and full thickness necrosis of the olfactory mucosa localized to the ventral and dorsal meatus, respectively. Repeated exposure to the same concentrations caused necrosis of the olfactory mucosa with early mucosal regeneration that extended from the dorsal medial meatus to the caudal regions of the ethmoid recess. Acute exposure to 400 ppm H2S induced severe mitochondrial swelling in sustentacular cells and olfactory neurons, which progressed to olfactory epithelial necrosis and sloughing. CO immunoreactive cells were more frequently observed in regions of the olfactory mucosa commonly affected by H2S than in regions that were not. These findings demonstrate that acute exposure to >80 ppm H2S resulted in reversible lesions in the respiratory and olfactory mucosae of the CD rat and that CO immunoreactivity may be a susceptibility factor for H2S-induced olfactory toxicity in the rat.

Variability of electrophoretical mobility of nuclei in human ontogenesis

Estimation of human biological age is one of the most difficult objectives within the auksological sciences. The methods applied so far are not sufficient enough. Assessment of the electrophoretic mobility of cellular nuclei index (EMN index) offers new possibilities. The aim of the work was to examine the behaviour of EMN in various phases of human ontogenetic development. The study revealed that each of the age groups in consecutive phases of ontogenetic development presented specific values in EMN.

Scanning electron microscopy of angioarchitecture of palatine gingiva in young rabbits

The angioarchitecture of young rabbits' palatine gingiva was studied by using the corrosion resin cast method. The vascular corrosion casts were obtained using low viscosity resin (Mercox CL-2B) and were observed with scanning electron microscopy (SEM). The palatine gingiva had areas with various arrangements. The capillaries of the palatine gingiva and interdental papillae had numerous projections, but in the gingival sulcus, the blood vessels were arranged in a flattened network from their capillary extremities. The blood vessels supplying the alveolar bone were also clearly seen.

Histone H3 lysine 9 methylation is an epigenetic imprint of facultative heterochromatin

Post-translational modifications of histone amino termini are an important regulatory mechanism that induce transitions in chromatin structure, thereby contributing to epigenetic gene control and the assembly of specialized chromosomal subdomains. Methylation of histone H3 at lysine 9 (H3-Lys9) by site-specific histone methyltransferases (Suv39h HMTases) marks constitutive heterochromatin. Here, we show that H3-Lys9 methylation also occurs in facultative heterochromatin of the inactive X chromosome (Xi) in female mammals. H3-Lys9 methylation is retained through mitosis, indicating that it might provide an epigenetic imprint for the maintenance of the inactive state. Disruption of the two mouse Suv39h HMTases abolishes H3-Lys9 methylation of constitutive heterochromatin but not that of the Xi. In addition, HP1 proteins, which normally associate with heterochromatin, do not accumulate with the Xi. These observations suggest the existence of an Suv39h-HP1-independent pathway regulating H3-Lys9 methylation of facultative heterochromatin.

A qualitative and quantitative estimation of AgNORS in dysplastic and non-dysplastic leukoplakias

Using a silver staining technique, nucleolar organizer region--associated proteins (AgNORS) were studied in formalin, fixed paraffin embedded tissue blocks of normal oral buccal mucosa epithelium, leukoplakia with dysplasias and leukoplakia without dysplasias. Fifty cases, that comprised of 10 cases of normal oral buccal mucosa epithelium and 40 cases, of leukoplakia without dysplasia and with mild, moderate and severe leukoplakia were examined with respect to the relationship between AgNOR counts and histologic grading. The mean AgNOR count per nucleus increased from normal oral buccal mucosa epithelium to leukoplakia without dysplasia to leukoplakia with dysplasia. Higher counts, wider scatter and smaller size of AgNOR in the nuclei were seen as the grading of dysplasia increased from mild to severe. It is suggested that this method has potential in distinguishing between dysplastic and non dysplastic leukoplakias and for early diagnosis, prognosis and treatment planning of dysplastic lesions.

[Establishment of human immortalized oral epithelial cell line HIO615 induced by HPV16 E6 and E7]

OBJECTIVE

To establish an immortalized oral epithelial cell line.

METHODS

Normal human oral epithelial cells were transfected with HPV16E6/E7 open reading frames using recombinant retroviral system pLXSN. Expression of HPV16E6 and E7 protein were tested by Western blot in three kinds of cells. To define cellular biological characterization of HPV16E6/E7 transfected cells, a series analysis were performed, including protraction of growth curve, HE staining, immunocytochemical staining and scanning electron microscope observation. The tumorigenicity was assessed by colony formation and transplanting the cells into nude mice.

RESULTS

Human oral epithelial cells transfected with HPVE6/E7 has been in culture for over 18 months. The cell line was named HIO615. Western blot analysis showed HIO615 expressed HPV16 E6 and E7 protein. HIOC were positive for cytokeratin, tonofibril and desmosome as observed by scanning electron microscope. The number of large colonies of dense multilayer cells was low (0.77%). No tumor developed in nude mice injected subcutaneously with HIOEC.

CONCLUSION

A human immortalized oral epithelial cell line induced by HPV16E6 and E7 has been successfully established.

Morphological effects on the hard palatine mucosa of Calomys callosus submitted to experimental chronic alcoholism

The morphological effects of ethanol ingestion on the hard palatine mucosa of adult male Calomys callosus were observed. Twenty rodents were divided into two experimental groups: the control group received solid diet, Purina rat chow, and tap water ad libitum; the alcoholic group received the same solid diet and ethanol P.A. diluted 20% in water (v/v). After 270 days of treatment, all animals were sacrificed and the hard palatine mucosa were prepared for TEM and SEM methods. The epithelial cells of the alcoholic group showed some alterations like cytoplasmatic lipid droplets, pycnotic nucleus and increased mitochondrial size. The lamina propria also presented intense lipid droplets accumulation. The morphological changes suggested that chronic ethanol consumption was able to modify the integrity of the mucosa.

Characterization of organotypic keratinocyte cultures on de-epithelialized bovine tongue mucosa

Organotypic cultures have been used to study epithelial cell behavior for many years. The aim of this study was to develop an organotypic culture method that better mimics the three-dimensional morphology of interdigitating rete ridges and connective tissue papillae and that also conserves the basement membrane zone (BMZ). Bovine tongue mucosa connective tissue, separated from epithelium after 1 M NaCl incubation, was used as organotypic culture substratum for different human keratinocyte cell lines. Organotypic cultures were characterized by electron and immunofluorescence microscopy for expression of integrin subunits and extracellular matrix components. While spontaneously immortalized mucosal keratinocytes produced highly irregular stratified organotypic cultures, the normal human epidermal keratinocytes (NHEK) demonstrated culture morphology that resembled in vivo epidermis. However, in this model, the histomorphology, expression of differentiation markers involucrin, keratin 10 and 14, and integrins varied significantly between the cell lines. Some cultures appeared to have an extended survival since they were maintained up to 40 days without histological signs of degeneration. The ultrastructure of the BMZ including hemidesmosomes was similar to the normal dermo-epidermal junction. Extracellular matrix molecules, including tenascin, laminin-1 and -5, were expressed in the cultures demonstrating their secretion solely by keratinocytes. Distribution and expression of integrins in NHEK cultures was similar to that seen in vivo skin with the exception of additional expression of alpha5beta1 and alpha(v)beta6 integrins. Organotypic NHEK cultures show similarities to normal stratified epithelium and are potentially useful for multiple applications for studies on epithelial cell behavior in vitro.

[Cellular level of the body adaptation to the environmental exposure in the large industrial city (Saint-Petersburg)]

By methods of light and electron microscopy structural disturbances of heart, kidneys, liver and pancreas were studied in rats pups who were born and kept for a year at kindergartens of city districts diverse in level of environmental pollution (air and soil). The content of micronuclei in epitheliocytes of oral mucosa in 5-6 ys old children from the kindergartens was controlled in order to detect chromosome aberrations. The examination of morphofunctional state of the organs studied and cells containing micronuclei carried out in different districts of the city allowed to reveal correlation between disorders studied and the level of environmental pollution.

5-Fluorouracil induces autophagic degeneration in rat oral keratinocytes

In this study, we investigated the effect of 5-fluorouracil (5-FU) on the keratinocytes of oral epithelium. Female Lewis rats were given 5-FU i.v. and were killed 12, 24 or 36 h after injection. The buccal mucosa was dissected. The number of nuclei with DNA strand breaks and the total number of nuclei per volume of the epithelial basal cell layer was estimated using terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling. Epithelial cells were analysed by flow cytometry, transmission electron microscopy and a dye exclusion test. The number of cells with DNA strand breaks increased in 5-FU treated rats. Flow cytometry showed a decrease in cell size and an increase in granularity with increasing doses of 5-FU. Dye exclusion gave no indication of degenerate cell membranes. By transmission electron microscopy, the cells showed evidence of degeneration, shrinkage and loss of cell-to-cell contact. Vacuolation was extensive and, in contrast to apoptotic cells, nuclear chromatin condensation seemed to occur centrally in the nuclei. The results show that 5-FU treatment in vivo induces alterations in rat oral keratinocytes that are consistent with autophagic degeneration.

Fimbria-mediated bacterial adhesion to human oral epithelium

Oral mucosa biopsies and saliva samples from 12 individuals were processed for transmission (TEM) and scanning (SEM) electron microscopy with and without ruthenium red staining. Additionally performed microbiological estimations indicated in all bacteriological samples a facultative pathogenic flora. SEM and TEM investigation showed a diverse bacterial flora attached to the mucosal surface. Fimbriae comprising the glycocalyx and enabling bacterial attachment to the epithelial cells could be clearly visualised by ruthenium red. The only mode of bacterial attachment to the oral mucosa detected in the present investigation was fimbria-mediated adhesion and co-adhesion. The fimbria-mediated adhesion enables the bacterial persistence in the oral cavity and is the first step in the bacterial colonisation process.

Permeability barrier properties of oral keratinocyte cultures: a model of intact human oral mucosa

OBJECTIVES

The aim of this study was to establish whether an in vitro model of human oral mucosa had similar permeability characteristics to normal oral mucosa. Such a model would have considerable value as an alternative to the use of mucosal biopsies in studies of transmucosal drug delivery.

MATERIALS AND METHODS

Keratinocytes obtained from buccal mucosa, hard palate and abdominal skin were seeded onto inert collagen membranes (Cellagen Discs) or dead de-epidermised dermis (DDED) and grown either as submerged or air-liquid interface cultures. Subsequently the ultrastructural characteristics, permeability to water and barrier lipid content of the epithelial cultures were assessed and compared with samples of intact mucosa and skin.

RESULTS

All the cultures stratified into multilayered epithelia and displayed features of differentiation including tonofilaments, desmosomes and membrane coating granules. The permeability characteristics and barrier lipid content of the oral mucosal cultures resembled those of intact mucosa. By contrast, epidermal keratinocytes failed to produce a permeability barrier comparable with that of skin and had low levels of barrier associated lipids.

CONCLUSIONS

Cultures of human oral mucosal keratinocytes obtained from healthy adults develop similar permeability properties and barrier lipid composition to their site of origin. This model system may be useful for the evaluation of local and systemic oral mucosal drug delivery.

Neurogenic inflammation of gingivomucosal tissue in streptozotocin-diabetic rat

Previously it was assumed that nerve fibres are involved in the neurogenic inflammation induced by mechanical or chemical irriations. It has been also suggested that in diabetes mellitus the unmyelinated small diameter fibers are impaired as a result of diabetic neuropathy. Therefore, our aim was to study the alterations of the nerve processes in the gingivomucosal tissue in streptozotocin (STZ)-diabetic rats. Light- and electronmicroscopical examinations were made to analyze the changes in nerve fibres. After one week of steptozotocin treatment, the gingivomucosal tissue had inflammatory cell infiltration and some degenerated nerve fibres were also observed. Dense mitochondria, disorganization of cell organelles, and appearance of myelin-like dense bodies were found in the axons of degenerared nerve fibres. Semiquantitative analysis showed that 14 +/- 4% of the unmyelinated nerve fibres degenerated after one week of STZ treatment. However, degeneration of the myelinated nerve fibers was not observed. Two weeks after STZ treatment, most of the unmyelinated and myelinated nerve fibers showed degeneration (86 +/- 5%) and the placement of the ligature revealed a non-inflammatory connective tissue adjacent to a normal epithelium. The myelin sheath was disrupted and dark axoplasm with cytolysosomes became manifest. These findings demonstrated that both unmyelinated and myelinated nerve fibers are altered and inflammatory reaction exists in the gingivomucosal tissue only in the early stage of diabetes mellitus.

[Ultrastructural differences between leukoplakia with and without dysplasia]

Leukoplakias with similar clinical appearances have presented with very different histopathological characteristics. In this study we investigate in depth the cellular ultrastructure of the tissues which determines the clinical behaviour of these lesions.

AgNORs in hyperplasia, papilloma and oral squamous cell carcinoma

Ten inflammatory fibrous hyperplasias, ten papillomas, and nineteen oral squamous cell carcinomas were analyzed by the AgNOR technique to determine if different disturbances of oral epithelia presented different AgNOR counts. The papilloma group showed higher mean AgNOR counts (3.15 +/- 0.58) than the hyperplasia group (1.98 +/- 0.24) and smaller than the well-differentiated oral squamous cell carcinoma group (6.56 +/- 1.25) and poorly differentiated oral squamous cell carcinoma group (7.07 +/- 1.60). The differences among the groups of lesions were statistically significant (P < 0.05) except between the well differentiated oral squamous cell carcinoma group and the poorly differentiated oral squamous cell carcinoma group. Our findings suggest that the cellular proliferation ratio in papillomas is greater than hyperplasias and smaller than carcinomas.

DNA damage in buccal epithelial cells from individuals chronically exposed to arsenic via drinking water in Inner Mongolia, China

The purpose of this pilot study was to assess DNA damage in buccal cells from individuals chronically exposed to arsenic via drinking water in Ba Men, Inner Mongolia. Buccal cells were collected from 19 Ba Men residents exposed to arsenic at 527.5 +/- 23.7 micrograms/L (mean +/- SEM) and 13 controls exposed to arsenic at 4.4 +/- 1.0 micrograms/L. DNA fragmentation by the DNA ladder and TUNEL assay were used to detect DNA damage in buccal cells. In the DNA ladder assay, 89% (17/19) of the arsenic-exposed group showed < 100 bp DNA fragments, in contrast to 15% (2/13) of the controls (p < 0.0001). For the TUNEL assay, the mean frequencies of positive cells were higher in the exposed group (15.1%) than in the controls (2.0%) (p < 0.0001). This study showed that high arsenic exposure via drinking water resulted in DNA damage and DNA fragmentation in buccal cells thus may be an appropriate biomarker for assessing chronic effects of arsenic in humans. A study investigating DNA fragmentation from the individuals with low levels of arsenic exposure in this population is in progress.