Fimbria-mediated bacterial adhesion to human oral epithelium

The white-rot fungus Marasmius quercophilus C30 is able to produce several laccases. The proportion of the enzymes produced depends on culture conditions. On malt medium, LAC1 was produced continuously over the 14 days of the cultivation period and was the only activity detectable. Copper increased total laccase activity by a factor 10 and induced the transient expression of one or more extra laccases in the culture medium. A combination of copper and p-hydroxybenzoic acid made it possible to extend the expression of induced laccase activities over the cultivation period and to reach a maximum activity 30 times higher than in non-induced culture. Extracellular laccases produced in this last condition were eluted as four peaks on an anion exchange column and were partially characterized.     

Lactate dehydrogenase in developing rat oral epithelium

Freeze-dried sagittal, whole-body sections of 10-day-old rats were incubated for lactic dehydrogenase (LDH) using different media in the presence of the inhibitors urea and fluoropyruvate. Phenazine methosulfate (PMS) and menadione, which are regularly used in current histochemical media and are believed to promote the demonstration of LDH activity, were also added and shown to be insufficient for the demonstration of total LDH activity, and PMS even seemed to have an inhibitory effect on LDH activity in oral epithelium. However, cumulated data from the different incubations show that the oral epithelium of developing rats may contain two different types of LDH, one in the basal cells with possibly aerobic characteristics, and another in the spinosum/granulosum cells with anaerobic characteristics.     

Staining of oral epithelium with the zinc iodide-osmium reaction

Summary Some of the parameters affecting the staining of keratinized oral epithelium with the zinc iodide-osmium reaction were examined using light and electron microscopy and electron probe microanalysis. Factors examined were block size, incubation temperature and the effect of aldehyde prefixation. Large blocks (4 mm cube) were subdivided after incubation and the staining of the centre and edge compared. Generally the reaction was more variable at the edge than in the centre. Small blocks (1 mm cube) showed a more intense reaction when incubated at 24°C than at 4°C. In all these preparations, final reaction product was seen over Golgi systems, lysosome-like bodies, membrane-coating granules and, in the more intensely stained regions, over endoplasmic reticulum and nuclear membranes as well. In prefixed material, mitochondria were frequently stained in addition to the other organelles. Energy dispersive analysis showed the reaction product to be similar in all preparations and to contain high levels of zinc and osmium but not iodine.     

Microridges of oral mucosal epithelium in carp,Cyprinus carpio

Summary The surface of carp oral mucosa is characterized by various patterns of microridges about 0.3 m wide, 0.1 m high, and of various lengths. To elucidate the derivation and function of these microridges, the oral epithelium was examined by light- and electron microscopy. Microridges were present only on the surfaces of the superficial cells. Therefore, microridges on renewed superficial cells are presumed to be formed after old superficial cells have been discarded, and the various patterns of microridges found on the cell surface appear to indicate the progress of their development. In thin sections, the outer leaflet of the plasma membranes of microridges stained strongly with ruthenium red, and the underlying cytoplasm was packed with many fine filaments. The superficial cells contained many secretory vesicles that were PAS-positive but Alcian blue-negative at pH 2.5 and pH 1.0. However, after sulfation the vesicles gave a positive reaction with toluidine blue. These vesicles are secreted by exocytosis at the free surface of the cells. After release, the membranes of the vesicles are thought to be utilized for formation of microridges. On the basis of these observations, the possible function of microridges is discussed.This study was supported by grants from the Ministry of Education, Science and Culture, Japan     

Calcium transport across the isolated oral epithelium of scleractinian corals

Oral epithelia were isolated from Lobophyllia temprichii and Plerogyra sinuosa and placed in Ussing chambers. Calcium flux was measured under open circuit and short circuit conditions using ⁴⁵Ca. Only a small transepithelial potential of 1.5 mV was recorded under open circuit conditions and no effect on flux rates were observed when the preparation was short circuited. Unidirectional fluxes in single and paired experiments were consistently greater in the ectoderm to gastroderm direction than from gastroderm to ectoderm with net flux of Ca²⁺ frequently being more than 3x10^-4 Eq mm^-2 min^-1. A small number of paired experiments showed that net flux of Ca²⁺ was reduced by Sr²⁺ and sodium azide but not by dinitrophenol. Unidirectional fluxes from ectoderm to gastroderm appeared to have maxima in the early and late parts of the day when recorded between 0900 and 2100 hrs. It is concluded that active transport of Ca²⁺ occurs across the isolated oral epitheia and that this may be an initial step in the process of keletal Ca²⁺ deposition.     

Blocking of the cell division by stress-inducing electrical stimulation. A study in rat oral epithelium

The purpose of the present study was to localize in the cell cycle, the site of the stress-induced blockage of cells entering the mitotic phase, and to estimate the length of time this block is effective. A total of 140 rats were subjected to electrical stimulation applied by a live metal grill in the bottom of their cages. Forty animals left undisturbed in the cages were used as controls. At various intervals after the start of electrical stimulation, groups of animals were killed and histologic sections were prepared of the palatal mucosa. The number of prophases, metaphases, and ana/telophases was counted in the epithelium in three sections of each animal. Electrical stimulation for 1 min resulted in a blocking of the entrance of cells into mitosis, followed by a transient increase in the number of mitotic figures to a level much higher than that of the controls. Electrical stimulation for 10 min resulted in the maintenance of the blocking effect for approximately 45 min. By renewed electrical stimulation the period of blockage was extended for a further 35 min. In each experiment the number of prophases decreased immediately after the start of electrical stimulation, indicating that the site of the blockage of the entrance of cells into mitosis is located near the G2/M transition.     

A,B and H isoantigens in atypical oral epithelium

Summary The red cell adherence (RCA) test was used for demonstration of blood group isoantigens A, B and H in epithelial lesions of the oral cavity. Study of normal squamous epithelium of the oral cavity with immunofluorescence showed the possible association of blood group isoantigens with the intercellular substance and their probable accumulation in spaces between desmosomes. In 31 cases of malignant tumors, a complete absence of isoantigens was found in 27 (87%), and partial loss in 2 (6.5%); in 2 cases of squamous cell carcinoma, the epithelial cells retained the isoantigen (6.5%). The second group of 34 cases included non-neoplastic changes such as leukoplakia, hyperkeratosis, dyskeratosis, pseudoepitheliomatous hyperplasia, or ballooning degeneration. A complete absence of isoantigens was found in 16 cases (47%), patchy distribution in 9 cases (26.5%); the remaining 9 cases (26.5%) retained the antigens. No correlation was found between the type and degree of epithelial atypia in non-neoplastic lesions and the absence of blood group substances. The loss of isoantigens A, B and H in neoplastic, pre-neoplastic, or even some regenerative or degenerative epithelial lesions suggests an aberration in their synthesis under abnormal conditions.     

Regional variations of cell surface carbohydrates in human oral stratified epithelium

The distribution of blood group carbohydrate chains with antigen A, B, H type 2 chain (A and B precursor), and N-acetyllactosamine (H type 2 precursor) specificity was studied in human oral epithelium from different anatomical regions. These represented various epithelial differentiation patterns such as non-keratinized, parakeratinized, and orthokeratinized stratified squamous epithelium. The material included buccal and palatal epithelium from 20 persons with blood group A or O, gingival, and alveolar epithelium from 10 persons with blood group A or B, and buccal metaplastically keratinized epithelium from nine blood group A, two blood group B, and nine blood group O individuals. The blood group carbohydrate chains were examined in tissue sections by immunofluorescence microscopy. The A and B blood group antigens were detected by human blood group sera, and antigen H type 2 chains and N-acetyllactosamine by murine monoclonal antibodies. Each antigen showed a similar staining pattern in buccal and alveolar epithelium (non-keratinized) which differed considerably from that seen in palatal and gingival epithelium (ortho- and parakeratinized). The expression of blood group antigens A or B and the precursor antigen H type 2 chains in metaplastically keratinized buccal epithelium was found to differ significantly from that seen in normal non-keratinized buccal epithelium. The regional variations demonstrated in cell surface carbohydrates are suggested to reflect differences in tissue differentiation.     

Chemosensory cells in the oral epithelium of Raja clavata (Chondrichthyes)

Examination by scanning and transmission electron microscopy (SEM and TEM) has found no actual taste buds in the mouth of Raja clavata. Prominences of the epithelium on the roof and floor of the mouth, and on the oral valves, contain large numbers of innervated bipolar cells, not associated in the form of taste buds, with a cytology intimating that they have a chemosensory function. The apices of these sensory cells, each bearing a group of microvilli, protrude between the superficial epithelial cells. Neurite profiles are associated with the sensory cells; synaptic specializations are marked by a cluster of vesicles with inconspicuous dense cores and some densities on the cell membrane. Shrunken, electron-dense, cell profiles are interpreted as apoptotic. Shrunken sensory cell profiles are commoner than similar epithelial cells, especially in young individuals, indicating a relatively rapid turnover of sensory cells. The epithelium contains a variety of granulocytic leucocytes, some of which contain large phagosomes.