In vitro binding of Candida albicans yeast cells to human fibronectin

The binding of Candida albicans yeast cells to human fibronectin (Fn), a major glycoprotein of mammalian cells, was studied using an in vitro assay. Adherence was quantitated in microtiter dishes coated with Fn to which radiolabeled yeast cells were added. Under optimum conditions of the assay, i.e., 1 mM CaCl2 and 70 micrograms Fn protein, approximately 40% of the radiolabeled yeast cells adhered to the Fn. Adherence to Fn was greater at 30 degrees C than at 4 degrees C and was greater with viable yeast cells than with heat-killed cells. Candida albicans (two strains) and C. tropicalis adhered to Fn to a greater extent than C. pseudotropicalis, C. krusei, or Saccharomyces cerevisiae. Pretreatment of C. albicans with chymotrypsin, pronase, or papain, but not pepsin, decreased adherence to Fn. Blocking experiments using mannan, sugars, or amino sugars were carried out by preabsorbing the Fn with each of the above-mentioned compounds. Candida mannan blocked adherence of C. albicans to Fn. The mannan effect was dose dependent. However, adherence of C. albicans to Fn was not significantly reduced by mannose, glucose, or several other sugars. The role of FN as a receptor for the binding of C. albicans yeast cells to buccal and vaginal epithelial cells was investigated also using an in vitro assay. We determined, using indirect fluorescent antibody techniques, that both buccal and vaginal epithelial cells possessed Fn. In addition, yeast cells, when pretreated with Fn, showed reduced adherence with buccal and vaginal cells when compared with nontreated cells. These studies may indicate a role for Fn in the adherence of C. albicans to buccal and vaginal epithelial cells.

Do pili play a role in pathogenicity of Haemophilus influenzae type B?

Surface components of Haemophilus influenzae type b (Hib) responsible for mucosal adherence were identified through assay of in-vitro attachment to human buccal epithelial cells (EC). Among many Hib strains from cerebrospinal fluid, blood, or the nasopharynx (NP), two isolates from NP were found to be exceptionally adherent. Adherence correlated with agglutination of human red blood cells (RBC). The adherent strains displayed pili, not previously described for Hib or other encapsulated H. influenzae. Moreover, highly adherent, piliated subpopulations of bacteria could be selected from any strain, but were lost upon subculture. Thus, the potential to express pili may be general for Hib and may aid the NP colonisation which precedes systemic invasion by this organism. Piliation was correlated with the amount of an outer membrane protein with a molecular weight of about 20,000 daltons, which had proved to be immunogenic in an 8-month-old child.

A possible relation between pKa 1 and lipid solubility and the amounts excreted in urine of some tobacco alkaloids given to man

The amount of unchanged (—)-nicotine, (—)-nornicotine, (—)-methylanabasine and (—)-anabasine excreted in the urine after oral administration to man was dependent on urinary pH while that of (—)-cotinine depended on urinary pH and on urine flow rate. No unchanged β-nicotyrine, β-nornicotyrine or myosmine was detected in urine. More nornicotine and anabasine than their corresponding tertiary amines nicotine and methylanabasine were excreted unchanged in the urine. Correlations of pKa1 and lipid solubility and the urinary excretion of these compounds were made.

Association of food lectins with human oral epithelial cells in vivo

The association of wheat germ agglutinin (WGA) and peanut agglutinin (PNA) with oral tissues after eating raw wheat-germ or raw peanuts, respectively, was determined. An indirect enzyme-linked immunoassay (ELIA) was used to detect WGA and PNA on epithelial cells. Buccal and tongue epithelial cells, and preparations of salivary sediment exhibited ELIA units of WGA and PNA significantly above background after eating 2--7 g of wheat-germ or 25 g of raw peanuts, respectively. Both lectins were detected also in preparations of salivary bacteria where they persisted for 1--6 h. Samples collected after eating raw wheat-germ and incubated with N-acetylglucosamine, or samples collected after eating raw peanuts and incubated with galactose had reduced ELIA units of lectin present. This suggests that the lectins were not non-specifically adsorbed or present as unbound food particles. Pretreating buccal epithelial cells in vitro with 25 micrograms of WGA increased the numbers of Streptococcus sanguis FC-1 cells which attached. Similarly, statistically significantly higher numbers of Strep. sanguis cells attached to buccal cells which were collected from donors after they had eaten raw wheat-germ compared to buccal cells collected prior to eating.

Evaluation of a method to study the uptake of prednisolone sodium phosphate from different oral mucosal sites

A filter paper disk method for the delivery of drugs to oral mucosal sites was evaluated. The water-soluble steroid prednisolone sodium phosphate was chosen as the tracer drug. The in vitro recovery of the steroid from the filter paper disks after placement onto glass was greater than 95% and within the pipetting error for the method. Filter paper disks containing 1.25 mg doses of prednisolone sodium phosphate were placed on three different intraoral sites for 5 minutes and the drug retention was calculated in six volunteers. The mean percentage retention at the three sites was 65.4% for the sublingual mucosa, 24.1% for the buccal mucosa, and 9.9% for the palatal mucosa. The differences between the sites were all significant. The method may be useful for studying the retention of other drugs at various oral mucosal sites and for determining the factors that affect such retention.

Effects of chlorhexidine on the structure and permeability of hamster cheek pouch mucosa

This study examined the effects of chlorhexidine (CHD) on the clinical appearance, morphology, and in vitro permeability of hamster cheek pouch mucosa. The cheek pouches were treated daily for 3 weeks with topical applications of saline, 0.2% CHD, or 2.0% CHD. Treatment with 2.0% CHD resulted in the formation of discrete white lesions in every animal in the group, whereas no changes were identified in any animal treated with 0.2% CHD or saline. Upon microscopic examination it was determined that treatment with 2.0% CHD resulted in a statistically significant (P less than 0.01) increase in epithelial thickness, when compared to the other groups, and the lesions were found to consist of hyperplastic areas of epithelium with associated inflammatory cell accumulations. Daily treatments with 2.0% CHD, 0.2% CHD or saline had no effect on the very low permeability of cheek pouch mucosa to 14C-CHD. However, treatment with 2.0% CHD resulted in decreased permeability to 3H2O (P less than 0.05) when compared to the other groups. Treatment with 2.0% CHD also resulted in a thickened permeability barrier (P less than 0.01), as determined using a tracer, horseradish peroxidase. It is concluded that topical applications of 0.2% T CHD have no detectable effect on cheek-pouch mucosa while applications of 2.0% CHD result in hyperplasia and a decrease in mucosal permeability. Our results suggest that CHD should be used with caution clinically and at a concentration of 0.2% or less.

Buccal drug absorption. II: In vitro diffusion across the hamster cheek pouch

The in vitro diffusion of a series of substituted acetanilides across the hamster cheek pouch was studied. The keratinized epithelial layer of the cheek pouch appeared to provide the major barrier to diffusion of these compounds. Linear relationships were found for plots of log epithelial permeability (Pe) versus the log of the octanol-buffer partition coefficient (PCoct; r = 0.712), and log Pe versus the log of the isooctane-buffer partition coefficient (PCiso; r = 0.869). Comparison of the in vitro data with in vivo data obtained in humans using the buccal absorption test showed good correlation (r = 0.878) between Pe and percent buccal absorption in 5 min. These results suggest that diffusion across the hamster cheek pouch may have some utility in the prediction of human buccal absorption.

The buccal absorption of some barbiturates

The buccal absorptions of five barbiturates have been determined over the pH range 3 to 9. The absorptions increased as the pH decreased until pH 5.5 when they remained constant. No correlation between the absorptions and chloroform–0.1n HCl partition coefficients was apparent, indicating that the adsorptive power of the buffer-buccal membrane interface may represent more exactly the real affinity of the membrane for barbiturates than do partition coefficients with chloroform.

Inhibition of lectin-binding to saliva-treated hydroxyapatite, to buccal epithelial cells, and to erythrocytes by salivary components

The influence of human saliva on the binding of several lectins to saliva-treated hydroxyapatite surfaces which mimic the teeth, to buccal epithelial cells, and to erythrocytes was determined. Clarified whole saliva inhibited binding of 3H-labeled concanavalin A, wheat germ, soy bean, Ulex europaeus, and peanut agglutinins to saliva-treated hydroxyapatite by 75 to 95%, depending on lectin concentration used. Different fractions of saliva-inhibited binding of different lectins. For example, salivary mucins reduced the binding of wheat germ agglutinin to saliva-treated hydroxyapatite, but they did not significantly affect binding of other lectins studied. Components of saliva also inhibited lectin-mediated hemagglutination. Using an indirect enzyme-linked immunoassay, wheat germ and peanut agglutinins were found to bind in a specific manner to human buccal epithelial cells, and this was also greatly reduced by saliva. The data suggest that one of the major functions of salivary and other alimentary secretions may be to reduce the extent of interaction of dietary lectins with mucosal surfaces.

Lipoxygenase activities of the epithelial cells of the human buccal cavity

The lipoxygenase activities of cultured human buccal epithelial cells and cells taken ex vivo from the human buccal cavity were compared. Lipoxygenation by cultured cells exhibited exclusively omega-6 positional specificity. A membrane-damaging event such as freezing was required for activation. In contrast, after simple addition of arachidonic acid, the ex vivo buccal cells produced predominantly 12-hydroxyeicosatetraenoic acid. Chromatography on chiral columns yielded products which had an (S) configuration at the site of oxygen insertion. 5-hydroxyeicosatetraenoic acid was transformed by ex vivo buccal cells to 5(S),12(S)-dihydroxyeicosatetraenoic acid. These products could have a role in modulation of inflammatory states of the oral cavity.

Differential distribution of immunohistochemically detected keratin proteins in mammalian oral epithelia

Keratin proteins were immunohistochemically demonstrated in different parts of the oral epithelium. Keratin staining in the squamous-cell epithelium was restricted to the spinous and granular cell layers, with a comparatively low reaction in the basal layer cells and none in the superficial cornified layer. In comparing the keratin staining levels, those in the buccal and sublingual epithelia were rather higher than those in the hard palatal epithelia. Staining intensities for keratin proteins were not the same in either different locations of the oral epithelium or in the same location in different animals.

Autoradiographic demonstration of DNA synthesis in selected epithelial tissues in male rats

Eleven white male rats received intravenous injections of thymidine -3H at a dose rate of 1 μc/gm body weight. The rats were killed at four-hour intervals over a 24-hour period Epithelial specimens from the hard and soft palate, cheek, skin, and tail were subjected to autoradiography. The results confirm prior data from liquid scintillation studies, which showed a maximal DNA synthesis at 4:30 to 8:45 AM and minimal synthesis at 3:40 to 8:30 PM.

Free-radical inhibition of ATPase in hamster cheek pouch homogenates

The effects of free-radicals generated by either the oxidation of hypoxanthine by xanthine oxidase (HX/XO) or the lipoxidation of arachidonic acid (AA) on the ATPase of the hamster cheek pouch has been studied. Cheek pouches were removed from female golden syrian hamsters and homogenized. ATPase activity was measured by the production of Pi at 37 degrees. HX/XO and AA were added at a final concentration of 9.6 X 10(-5) M HX with 5 X 10(-2) units HX and 5 X 10(-5) M AA with and without 1 X 10(-4) M ouabain. HX/XO produced a 24.7% inhibition alone and 35.0% when combined with ouabain. Ouabain alone produced a 7.1% inhibition. AA produced a 23.6% inhibition alone and 24.3% inhibition when combined with ouabain. Ouabain alone produced a 5.4% inhibition in this series. When AA was added in doses ranging from 1 X 10(-5) to 2 X 10(-3) M, a plot of percent inhibition versus log dose followed a typical sigmoid type curve. The IC50 was 1.5 X 10(-4) M. These results suggest that free-radicals are capable of inhibiting the ATPase found in the hamster cheek pouch tissues. The possible modes of action of the free-radicals in producing this inhibition are discussed.

Spectrofluorimetric analysis and buccal absorption of medifoxamine

Medifoxamine is a new investigational antidepressant drug. Its buccal absorption at pH 5-9, which can be considered as an in-vivo model of passive drug transfer through a lipid membrane, was studied in six normal, healthy volunteers to predict its pharmacokinetic profile in man. Maximum absorption of medifoxamine occurred at pH 8, which is close to its pKa (8.5).