Chromatin structure and the state of human organism

The state of chromatin in human buccal epithelium cell nuclei upon the influence of sport trainings was investigated. Chromatin state was evaluated in interphase buccal cell nuclei after orcein staining. The heterochromatin granule quantity (HGQ) was estimated in 30 nuclei per sample, and for every donor the mean HGQ value per 30 cells was determined. Donors of masculine sex, aged from 18 to 48 years performed training walks and samples of buccal epithelium were collected. Sportive charges induced the process of chromatin condensation in cell nuclei. After the period of repose (24-48 h) the HGQ decreased to control level therefore the process of chromatin decondensation was observed. The state of chromatin changes in connection with circadian rhythm. Chromatin became more condensed at nighttime and less condensed in the morning. Hormones such as adrenaline, noradrenaline, and hydrocortisone in vitro induced the increase of HGQ.

Evaluation of cisplatin + 5-FU, carboplatin + 5-FU, and ifosfamide + epirubicine regimens using the micronuclei test and nuclear abnormalities in the buccal mucosa

In the present work, the micronuclei (MN) test was performed in buccal mucosal samples from patients with cancer, with (pre- and post-treatment) and without genotoxic chemotherapy (GC), identified micronucleated cells (MNC) and nuclear abnormalities (binucleated cells (BN), pycnosis (PN), "broken-egg" (BE), condensed chromatin (CC), karyorrhexis (KR), and karyolysis (KL). The objective was to evaluate the genotoxicity of cisplatin + 5-Fluorouracil (5-FU), carboplatin (CBP) + 5-Fluorouracil, and ifosfamide (IFO) + epirubicine (EPI) regimens. The ifosfamide + epirubicine regimen described here produced a micronucleogenic effect, whereas the regimens using platinum compounds were cytotoxic for buccal mucosal cells, which probably explain the absence of increase of micronucleated cells in these samples compared with basal levels. In patients with cancer (with and without genotoxic chemotherapy), the numbers of MNC, PN, KR, total nuclear abnormalities and KL increased, together with a decrease in BN cells and CC. On the other hand, as consequence of the cytotoxicity of the drugs, the number of binucleated cells decreased and the number of karyolytic cells increased. These results could be used as a cytotoxicity marker in the future studies for different drugs.

The assessment of cell proliferation during 9,10-dimethyl-1,2-benzanthracene-induced hamster tongue carcinogenesis by means of histone H3 mRNA in situ hybridization

The aim of this study was to investigate cell kinetics and ultrastructural changes during carcinogenesis using a hamster 9,10-dimethyl-1,2-benzanthracene (DMBA)-induced tongue cancer model. Five squamous cell carcinomas, five dysplastic epithelia, seven hyperplastic epithelia, and four normal epithelia were obtained from 21 hamster tongues by applying 1.0% acetone solution of DMBA on the left lingual mucosa after scratching with a root canal broach. Ultrastructural examination revealed that the number of microvilli increased, whereas that of desmosomes decreased during carcinogenesis. Cell proliferation was analyzed by means of 5-bromodeoxyuridine (BrdU) immunohistochemistry and in situ hybridization (ISH) for histone H3 mRNA. The BrdU and histone H3 mRNA labeling indices (LIs) were lowest for normal epithelium, higher for hyperplastic and dysplastic epithelia, and highest for squamous cell carcinoma. Cytoplasmic histone H3 mRNA and nuclear BrdU were localized in virtually identical areas of serial sections. The correlation coefficient for the relationship between these two LIs was 0.97 ( P << 0.001). These results suggest that the assessment of cell proliferation using H3 mRNA ISH will be a useful technique for investigating biological behavior during carcinogenesis.

Effect of cadmium on the floor of the mouth on rats during lactation

Cadmium (Cd) present in the air, drinking water and food has the potential to affect the health of people, mainly those who live in highly industrialized regions. Cd affects placental function, may cross the placental barrier and directly modify fetal development. It is also excreted into milk. The body is particularly susceptible to Cd exposure during perinatal period. The effect on rat oral epithelium (floor of the mouth) after continuous exposure to drinking water containing low levels of Cd during lactation was studied. Female rats were supplied with ad libitum drinking water containing 300 mg/l of CdCl2 throughout the whole lactation period. Control animals received a similar volume of water without Cd. Lactating rats (21 day-old) were killed by lethal dose of anesthetic. The heads were retrieved, fixed in "alfac" solution (alcohol, acetic acid and formaldehyde) for 24 h, serially sectioned in frontal plane, at the level of the first molars. The 6 micro m sections were then stained with hematoxylin and eosin. Nuclear epithelium parameters were estimated, as well as cytoplasm and cell volume, nucleus/cytoplasm ratio, numeric and surface densities, and epithelial thickness. Mean body weight was 34.86 g for the control group and 18.56 g for the Cd-treated group. Histologically, the floor of the mouth epithelium was thinner in the treated group, with smaller and more numerous cells. In this experiment, Cd induced epithelial hypotrophy, indicating a direct action in oral mucosa cells, besides retarded development of the pups.

Genetic damage in exfoliated cells from oral mucosa of individuals exposed to X-rays during panoramic dental radiographies

The genotoxic effects of X-ray emitted during dental panoramic radiography were evaluated in exfoliated cells from oral epithelium through a differentiated protocol of the micronucleus test. Thirty-one healthy individuals agreed to participate in this study and were submitted to this procedure for diagnosis purpose after being requested by the dentist. All of them answered a questionnaire before the examination. Cells were obtained from both sides of the cheek by gentle scrapping with a cervical brush, immediately before the exposure and after 10 days. Cytological preparations were stained according to Feulgen-Rossenbeck reaction and analyzed under light and laser scanning confocal microscopies. Micronuclei, nuclear projections (buds and broken eggs) and degenerative nuclear alterations (condensed chromatin, karyolysis and karyorrhexis) were scored. The frequencies of micronuclei, karyolysis and pycnosis were similar before and after exposure (P > 0.90), whereas the condensation of the chromatin and the karyorrhexis increased significantly after exposure (P < 0.0001). In contrast, both bud and broken egg frequencies were significantly higher before the examination (P < 0.005), suggesting that these structures are associated to the normal epithelium differentiation. The results suggest that the X-ray exposure during panoramic dental radiography induces a cytotoxic effect by increasing apoptosis. We also believe that the score of other nuclear alterations in addition to the micronucleus improves the sensitivity of genotoxic effects detection.

[Adhesion of lactic acid bacteria to epithelium of different cavities of the human organism]

During investigation of adhesive properties of lactic acid bacteria it was found out that 11 strains adhered to buccal intestinal and vaginal epithelium of human. The highest adhesive activity was detected in enterococci (adhesive index 7.75-14.26), lower one--in streptococci (6.40-9.16). In lactobacilli adhesive properties manifested in different ways: Lactobacillus acidophilus strains adhered more often to buccal epithelium (2.58-4.60) and rarely--to intestinal and vaginal. L. plantarum manifested high adhesive activity (8.03 -9.69) to buccal epithelium and lower one--to the rest of epithelium types. Monosaccharide composition of glycocalix of 6 strains of lactic acid bacteria was studied to understand the adhesion mechanism. It was shown that surface structures of this microorganism interact with plant lectins, specific to certain monosaccharides.

Ultrastructures of mechanoreceptors in the oral mucosa

The present review describes the fine structures of lamellated mechanoreceptive corpuscles, Merkel cell-neurite complexes and free nerve endings in the oral mucosae of mammals, with special attention to axon terminals and lamellar cells. The mechanoreceptive nerve endings of the oral mucosa were studied using histochemistry, immunohistochemistry and transmission electron microscopy techniques. The organized mechanoreceptive corpuscles are present in the mucosae of gingiva, cheek, tongue and soft and hard palate. They are elongated or globular in shape, being located in the connective tissue papillae. The capsule is composed of several layers of cytoplasmic extensions of perineural cells. Numerous bundles of collagen fibers are noted at the periphery of the corpuscle. The lamellated corpuscles are surrounded by several layers of superimposed flattened capsular cell processes. The interlamellar spaces are 0.2-0.4 micron in width and filled with thin fibrillar collagen fibers embedded in the amorphous substance. The lamellar cells contain rich microtubules and are characterized by the presence of caveolae on the surface plasma membrane. The terminal axon contains an abundance of mitochondria and small clear vesicles (20-50 nm in diameter). There are neurofilaments in the center of the axon terminal. Intermediate-type junctions are seen between the adjacent lamellar cells and between the axon and adjacent lamellae. The free nerve endings are found in the subepithelial regions, very close to the basal laminae of mucosal epithelium. They are surrounded by a thin cytoplasm of Schwann cells. Sometimes Schwann cell basal larinae become multilayered. Merkel cells are present within the basal layer of mucosal epithelium and contain characteristic electron-dense granules that are located almost exclusively at the side of cytoplasm in contact with axon terminals. Intermediate-type junctions are noted between axon terminals and Merkel cells.

Merkel cells, corpuscular nerve endings and free nerve endings in the mouse palatine mucosa express three subtypes of vesicular glutamate transporters

The hard palate of rodents is a mucous membrane covered by a keratinized epithelium that typically contains Merkel cell (MC)-neurite complexes. MCs have engendered considerable research activity because of their involvement in mechanoreception and possibly also Merkel cell carcinomas. MCs derive from the neural crest, differentiate under control of peripheral nerve factors, are enriched in large dense core vesicles, and secrete neuropeptides and other neuroactive molecules. Upon stimulation, MC-neurite complexes produce slowly adapting type I responses. Here we emphasize that the murine hard palate is a highly differentiated sensory region, as shown by intravital staining with a styryl dye and immunocytochemistry with antibodies to vesicular glutamate transporters (VGLUTs). The entire palate contained densities of sensory endings and MC-neurite complexes, that nearly paralleled in abundance the vibrissal pads. MCs were differentially distributed in the murine palate; clusters of MCs were most abundant in the antemolar and intermolar rugae, while individual MCs were particularly enriched in the rugae at the mid-portion of the palate and in the postrugal field. VGLUT1, VGLUT2 and VGLUT3 were expressed in MCs throughout, although immunostained MCs were most frequently encountered in intermolar than antemolar rugae. The same transporters were also present in corpuscular endings at the summit of the rugae and in intraepithelial free nerve endings throughout the palate. VGLUTs presumably load glutamate into large dense core vesicles in MCs and into small clear vesicles in corpuscular and free nerve endings. The data suggest that glutamate release, or co-release, is likely to represent an important functional aspect of palatine Merkel cells and neighboring corpuscular and free nerve endings.

Optical sectioning using a fiber probe with an angled illumination-collection geometry: evaluation in engineered tissue phantoms

We present a fiber optic probe that combines polarized illumination and detection with an angled distal probe geometry to detect the size-dependent scattering at a specific depth within epithelium. Analysis of the scattering signal by use of Mie theory allows the extraction of scatterer size and size distribution-key parameters for precancer detection. The probe was evaluated in two tissue phantoms: polystyrene beads atop collagen gel and multiple layers of cancer cells atop collagen. We also present in vivo measurements in the oral cavity of normal volunteers. The sizes of scatterers extracted from the scattering spectra corresponded to independently measured values.

Separated dental laminae are present in the upper jaw of Mesoamerican lungless salamanders (Amphibia, Plethodontidae)

Plethodontid salamander species from Northern America exhibit a single, unseparated dental lamina in the upper jaw, which consistently provides teeth for the unpaired premaxillary and the two maxillary bones. During the distinct mating season, adult males of these species bear long, monocuspid, unbladed teeth in the entire upper jaw, which are used during courtship. However, plethodontid salamander species from Southern Central America studied so far show either three separated dental laminae or a single dental lamina with three distinguishable tooth-producing parts connected by non-producing parts. These species reproduce aseasonally and sexually mature males permanently bear long, monocuspid, unbladed teeth on the premaxillary only. As the formation of these long, monocuspid teeth depends on the presence of androgen-receptors in the tooth-forming tissues, the morphological separation of the dental lamina in plethodontid salamanders from Southern Central America is very likely to be a prerequisite for a region-specific expression of androgen-receptors in the tooth-forming tissues controlling the differentiated shape formation of teeth in these species. Seven species of plethodontid salamanders from Costa Rica and Panama were examined and, in all, a tendency to exhibit three separate dental lamina in the upper jaw was found, although the morphological separation is definitive only in Bolitoglossa colonnea, B. lignicolor, B. pesrubra, B. schizodactyla and B. striatula. B. dofleini and B. marmorea show a continuous dental lamina with non-producing parts at the transitional sites between the parts associated with the premaxillary and the maxillary bones.

[Experimental study on in vitro lamina propria engineering using oral fibroblast and polyglycolic acids]

PURPOSE

This study investigated the feasibility of lamina propria engineering in vitro using expanded oral fibroblast(OFC) and Polyglycolic Acids (PGA).

METHODS

OFC were isolated by tissue explant method and expanded in vitro. OFC (20x10(6)) of 3rd passage were collected and then seeded onto PGA unwoven fibers to form a cell-scaffold. The constructs were cultured in DMEM +10% FBS. The cell-scaffold constructs were observed continuously by microscope. Small fragments were harvested at 1 week for electromicroscope, histological and RT-PCR analysis.

RESULTS

At the sixth day, a neo-lamina propria was formed. HE and Masson stain revealed the formation of collagen fibers. RT-PCR revealed the new forming collagen was mainly type I collagen.

CONCLUSION

lamina propria tissue is possible to engineer in vitro using oral fibroblast and polyglycolic acids. At this basis, we can construct bi-layer tissue engineering oral mucosa in the further research.

[Morphological and cytochemical features of the gingival mucosal epithelium in women during different phases of the menstrual cycle]

Morphological analysis of smears of the gingival epithelium by computer-aided morphometry was carried out in women during the secretory and proliferation phases of the menstrual cycle. During the secretory phase the cell ratio was characterized by higher percentage of epitheliocytes in the terminal stages of differentiation. Size of the nuclei and cytoplasm of intermediate cells, concentration of total protein in them, number of the nucleolar organizer zones, and degree of bacterial contamination of epitheliocytes is higher during the secretory phase than during the proliferation phase.

Microcirculation and micromorphology of healthy and inflamed gingivae

Inflammation changes the microcirculatory and micromorphological dynamics of human gingiva. Laser Doppler flowmetry (LDF) and a replica technique for scanning electron microscopy (SEM) were used to examine the facial soft tissues of six maxillary anterior teeth, before and after treatment, in 12 patients exhibiting clinically healthy tissues and in 12 others with moderate gingivitis. All patients received oral hygiene instructions and scaling. The gingiva in the gingivitis group became healthy within 3 months after treatment. LDF results were recorded at the free gingivae, interdental gingivae, attached gingivae, and alveolar mucosae of the six maxillary anterior teeth. The gingival blood flows in the gingivitis group before treatment were significantly different from those in the healthy gingiva group. Flows were restored to the same level as the healthy gingiva, with no significant difference, at P > 0.01, 3 months after treatment. However, there were significant differences among sites during the same period. In addition, blood flow was reduced to a normal level after the inflammation subsided. Initially, the gingival morphology of the inflamed sites exhibited irregular free gingival margins, in contrast to that of healthy gingivae, which were characterized by rounded margins closely adapted to the tooth. One month post-treatment, the gingivae exhibited a wrinkled appearance, but they had reverted to normal micromorphology by 3 months post-treatment. The replica impression technique can be used to record gingival micromorphology both before and after reduction of inflammation.

Scanning electron microscopic observations of the basement membranes with dithiothreitol separation

Scanning electron microscopic (SEM) studies of the interstitial surface of the lamina densa can be performed with dithiothreitol separation, which is the only method of exposing this surface. SEM observation revealed the three-dimensional structures of the meshwork in the lamina densa and anchoring fibrils in dithiothreitol-separated specimens. Detection of the components of the basement membrane can be performed by immunoscanning electron microscopy on this exposed surface by comparing the backscattered and the secondary electron images. SEM observation also revealed the fine structure of the lamina fibroreticularis using separated dermis or the lamina propria mucosae.

Evaluation of cisplatin + 5-FU, carboplatin + 5-FU, and ifosfamide + epirubicine regimens using the micronuclei test and nuclear abnormalities in the buccal mucosa

In the present work, the micronuclei (MN) test was performed in buccal mucosal samples from patients with cancer, with (pre- and post-treatment) and without genotoxic chemotherapy (GC), identified micronucleated cells (MNC) and nuclear abnormalities (binucleated cells (BN), pycnosis (PN), "broken-egg" (BE), condensed chromatin (CC), karyorrhexis (KR), and karyolysis (KL)). The objective was to evaluate the genotoxicity of cisplatin+5-Fluorouracil (5-FU), carboplatin (CBP)+5-Fluorouracil, and ifosfamide (IFO)+epirubicine (EPI) regimens. The ifosfamide+epirubicine regimen described here produced a micronucleogenic effect, whereas the regimens using platinum compounds were cytotoxic for buccal mucosal cells, which probably explains the absence of increase of micronucleated cells in these samples compared with basal levels. In patients with cancer (with and without genotoxic chemotherapy), the numbers of micronucleated cells, pycnosis and karyolysis increased, together with a decrease in binucleated cells and chromatin-condensed. On the other hand, as consequence of the cytotoxicity of the drugs, the number of binucleated cells decreased and the number of karyolytic cells increased. These results could be used as a cytotoxicity marker in future studies for different drugs.

Ultrastructure of the gingiva in cardiac patients treated with or without calcium channel blockers

OBJECTIVES

In the last few years, several studies have suggested that periodontal diseases are related to the development of atherosclerosis and its complications. Our objective was to study the ultrastructural morphology of the gingiva from cardiac patients, some of whom were treated and some not with calcium channel blockers compared to a control group.

MATERIAL AND METHODS

Fifty-five patients were studied and grouped in the following way: (a) healthy group (HG) (n=12) healthy patients with at least two pockets between 3 and 5 mm; (b) cardiac group (CG) (n=12) patients with cardiac disease untreated with calcium channel blockers; (c) diltiazem group (DG) (n=13) cardiac patients treated with diltiazem; (d) nifedipine group (NG) (n=18) cardiac patients treated with nifedipine.

RESULTS

Ultrastructural studies in the CG showed inflammatory cells, collagen fibers disruption and a more extended morphologically compromised fibroblast mitochondria. Morphometric studies in CG showed mitochondria that were impaired in number but increased in volume, suggesting metabolic cell suffering. In DG and NG, morphometric data were similar to HG. The presence of myofibroblasts and collagen neosynthesis was detected in DG and NG.

CONCLUSIONS

Our data showed differences in the ultrastructure of the gingival fibroblasts between the studied groups; the DG and NG showed features that could be interpreted as an attempt to restore the cellular metabolic function.

[Electron microscopy in oral squamous cell carcinoma of elderly patients]

OBJECTIVES

Squamous cell carcinoma is the most frequent tumor occurring in the oral cavity. The aim of the study is to point out the fine-structural characteristics of the tumor cells and of the adjacent stromal cells, trying to establish a correlation between these characteristics and the biological behavior of the tumor.

MATERIAL AND METHODS

We performed an electron microscopic investigation for tree elderly patients diagnosed with oral squamous cell carcinoma.

RESULTS

The tumoral cells presented nuclear abnormalities and the reduction of the intercellular cohesion, through an increase in the intercellular spaces, and desmosomal modifications. Through the abundance and the variety of the cellular types, the stromal component represented a positive response from the host.

CONCLUSIONS

In the diagnosis of the oral carcinoma, the electron microscopic exam supplements the light microscopic investigation, revealing important morphologic elements at a subcellular level (regarding the nucleus, cellular organelles, and junctions).

Mitochondrial volume densities in the smokeless tobacco-treated hamster cheek pouch epithelium

OBJECTIVES

To compare the morphological changes and quantitative distribution of mitochondria in the hamster cheek pouch (HCP) epithelium treated with smokeless tobacco (ST).

MATERIALS AND METHODS

Archives of experimental material from previously published studies (Ashrafi et al., 1992) were utilized. Animals in experimental group received moist ST (snuff) in their right pouch, 5 days weekly for 24 months, while no snuff was given to control group. After 24 months, the epithelial tissues were processed for electron microscopy study. Volume densities of mitochondria were assessed by morphometry.

MAIN OUTCOME MEASURES

Mitochondrial volume densities in the two groups, experimental vs control.

RESULTS

In both control and experimental groups mitochondria were concentrated between the nucleus and basal cell plasma membrane. A decrease in the mean mitochondrial volume density (Vvmit) was observed from the basal layer to the more superficial layers in both groups. The experimental HCP displayed more mitochondria than control, and the granular epithelial cell layer in experimental group showed significantly a higher mean Vvmit than the control group (P = 0.03). It was concluded that greater numbers of mitochondria were retained in ST-treated granular cells of the hyperplastic epithelia than in the normal epithelium.

The effect of diabetes mellitus on the expression of Argyrophilic nucleolar organizer regions (AgNORs) in mucosal epithelium under experimental denture bases in rats

BACKGROUND

Expression of argyrophilic nucleolar organizer regions (AgNOR) was counted on mucosal epithelium to detect whether the AgNOR count (the number of AgNOR per nucleus) is, for 20 weeks, affected by streptozotocin-induced diabetes mellitus.

METHODS

Diabetic rats were applied non-denture wearing, non-pressure contact, continuous pressure (0.5, 1.5 or 3.4 kPa) and intermittent pressure (10.5, 33.0 or 81.7 kPa), respectively.

RESULTS

In the non-denture wearing or the non-pressure contact group, AgNOR count was almost constant (ranging 1.86-1.92) without significant difference. Under continuous pressure, AgNOR count significantly decreased at earlier stage and finally recovered to the non-pressure contact group. A similar effect of continuous pressure appeared to manifest itself in intermittent pressure, but to a greater degree. Consequently, AgNOR count under intermittent pressure showed no recovery at 20-week stage.

CONCLUSION

: Diabetes mellitus exerted, by itself, no influence on the cellular proliferative activity under continuous pressure, whereas the activity deteriorated under intermittent pressure.

Element release from titanium devices used in oral and maxillofacial surgery

Optical microscopy, scanning electron microscopy and X-ray microanalysis (EDS system) were used on c.p. titanium devices (21 grids and 10 plates) removed from 28 patients without signs of inflammation 6-24 months after surgery. Plates, grids and surrounding tissue were investigated to evaluate the titanium release and accumulation. Titanium was only present in the interfacial bone, probably due to fretting, and in all fibrous tissue surrounding the devices. Titanium content followed a decreasing gradient extending from the device surface and was not detected at a distance greater than 1mm. High titanium levels were found in blood cells in the connective tissue. In conclusion, titanium release from the devices stops only after bone is laid down on the titanium surfaces. Titanium release does not seem to interfere with the osteogenic process but perhaps may interact with it.

Evaluation of argyrophilic nucleolar organizer regions in oral tumor progression

The aim of this study was to compare the presence of nucleolar organizer regions (NORs) in normal oral mucosa, dysplasia and microinvasive carcinoma. All histological specimens were reviewed according to the modified classification and staging system for oral leukoplakia described by van-der-Waal et al. [Oral Oncol. 36 (2000) 264]. NOR quantification was performed with an image analyzer after staining by the argyrophilic nucleolar region technique. The morphometric results were statistically different for normal mucosa, dysplasia and microinvasive carcinoma. It was concluded that an increase of NOR activity follows the disease progression and may reflect the degree of cellular proliferation and malignancy.

The electrophoretical activity of the buccal epithelium cells nuclei in newborns of smoking mothers

The electrophoretical activity of nuclei (EMN) occurs in all cells of the human body. The EMN is variable and depends on the particular stage of human ontogenesis. The factors that modify the ontogenesis may influence the electrophoretical activity of nuclei. The aim of the study was to compare the index of electrophoretical activity of nuclei (index EMN) derived from the buccal epithelium of 40-week newborns (n = 26) from healthy, single pregnancies of smoking mothers with newborns (n = 31) of non-smoking mothers. The cells of the buccal epithelium were analysed using light microscope in the environment of alternating field (voltage 20-30 V; intensity 0.1 mA; frequency 1-2 Hz) generated by Biotest processor. In each group we estimated the number of cells with mobile nuclei and cells with motionless nuclei per 100 cells being observed. The result of this research was that there is not activity of nuclei in the group of newborns of smoking mothers (index EMN = 0 with p < 0.05). The absence of activity of nuclei makes it impossible to use the EMN method for estimation of biological age in the group of newborns of smoking mothers.

Recapitulation of oral mucosal tissues in long-term organotypic culture

To test the influence of fibroblasts on epithelial morphology and expression of keratinocyte proteins and barrier lipids, we bioengineered homotypic and heterotypic oral mucosae and skin using cultured adult human cells. Fibroblasts were allowed to modify collagen type I gels for 2 weeks before keratinocytes were added. The organotypic cultures were then grown at the air-liquid interface for 4 weeks. In homotypic combinations, epithelial morphology and protein expression closely mimicked those in vivo. In heterotypic combinations, the morphology resembled that in vivo and keratinocytes expressed their typical markers, except when skin keratinocytes were recombined with alveolar fibroblasts; they expressed K19, K4, and K13, which is similar to oral mucosal epithelia rather than to the epidermis. Morphologically, the stratum corneum layers were typical for the epithelial tissues. Grafting the bioengineered cultures to the backs of Nude mice did not change the results, suggesting that our findings are not merely a culture phenomenon. Lipid profiles of the homotypic combinations mimicked the profiles found in the normal epithelial tissues, except that the engineered alveolar epithelium expressed more ceramide 2 than that in vivo. In the heterotypic combinations, keratinocytes appeared to control the lipid profile, except in the combination of skin keratinocytes with alveolar fibroblasts, wherein the ceramide profile appeared to be partly that of alveolar epithelium and partly that of epidermis. These results suggest that cultured adult fibroblasts and keratinocytes are sufficient to recapitulate graftable oral tissues, and, except for alveolar fibroblasts, the type of fibroblast had little influence on keratinocyte differentiation.

Metabolic polymorphisms and the micronucleus frequency in buccal epithelium of adolescents living in an urban environment

Micronuclei and other biomarkers were evaluated in oral cells from 11- to 16-year-old girls living in a foster home in the central area of México City. Variables analyzed for possible association with these biomarkers include smoking habits, body mass index, metabolic polymorphisms for NAT1 and GSTM1 and whether the cells were obtained from the cheek or pharynx. The results indicated that individuals having the NAT1*10 homozygous genotype showed a significant increase in chromatin buds and binucleated cells. When the damage in the cheek was compared with damage in the pharynx, a significant increase in micronuclei and binucleated cells was found for the latter tissue in all the individuals analyzed.