Accessible sialic acid content of oral epithelial cells from healthy and gingivitis subjects

The purpose of the present study was to determine if there were differences in the quantity of accessible sialic acid on superficial epithelial cells collected from different areas of the mouth, and from healthy subjects with good oral hygiene, as compared to subjects with gingivitis. Superficial epithelial cells were collected by gently scraping the tongue dorsum, hard palate, free gingiva and buccal epithelium. The cells were washed and treated with clostridial neuraminidase to release accessible sialic acid; this was quantitated using a fluorometric assay. Buccal cells released an average of 62.6 ng sialic acid per 10,000 cells, which was nearly 3-fold more than cells from the hard palate (24.1 ng), free gingiva (21.9 ng), or tongue (15.4 ng). Buccal and free gingival cells collected from 5 healthy subjects had significantly higher levels of accessible sialic acid on their surface than cells collected from 5 subjects with gingivitis. These differences were significant at the p less than 0.001 and p less than 0.01 levels, respectively. The data obtained suggest that the oral hygiene status of an individual can influence the quantity of accessible sialic acid residues on oral epithelium; this would be expected to influence the attachment and colonization of bacteria which bind to sialic acid-containing receptors.

The fine structure and elemental analysis of keratinized epithelium of the filiform papillae analysis on the dorsal tongue in the American alligator (Alligator mississippiensis)

The filiform papillae of subadult alligator (120 cm-260 cm total length) tongues are examined by scanning electron microscopy and electron microprobe analysis. The filiform papillae form cone-like structures and are observed over the entire dorsal surface of a relatively long tongue with a round tip. The filiform papillae are composed of four layers; outer, upper intermediate, lower intermediate, and basal layer. The keratinized epithelial cells are analysed by the sulphur (S), and nitrogen (N) content levels. The S content is higher than that of N. In the anterior side of the filiform papillae, this content is lower than that in the posteriors. The S content is highest of all at about 2 microns in depth from the surface. These results suggest that the use of S concentration measurements may serve to be an effective tool for a simple, offhand evaluation of keratinization.

Peptide-containing nerve fibers in the circumvallate papillae

The occurrence and distribution of an array of neuropeptides and dopamine-beta-hydroxylase in the circumvallate papillae of monkey, pig, cow, ferret, cat, rat and mouse was studied by immunocytochemistry. The animals were chosen to represent species with different diets. Substance P/neurokinin A- and calcitonin gene-related peptide-containing fibers were numerous in the circumvallate papillae of all animals examined, with the highest frequency in monkey, pig, cow, rat and mouse; in ferret and cat moderate numbers were detected. Vasoactive intestinal peptide/peptide histidine isoleucine amide-containing fibers were numerous in the circumvallate papillae of pig, while they were moderate in number in monkey, ferret and mouse. Neuropeptide Y-containing fibers were few to moderate in number in the circumvallate papillae of all species. Galanin-containing fibers were numerous in the pig circumvallate papillae, while only a few fibers could be detected in monkey, cow, cat, rat and mouse. Somatostatin-containing fibers were seen only in the cat circumvallate papillae, gastrin-releasing peptide-containing fibers in the cow and cat, cholecystokinin/gastrin-containing fibers in the pig and cow. Dopamine-beta-hydroxylase-containing fibers were detected in all animals studied. They were few to moderate in number in the circumvallate papillae. There was no obvious link between the peptidergic innervation pattern and the food habits.

Leucine-enkephalin-, neurokinin A- and cholecystokinin-like immunoreactivities in the guinea pig tongue

The occurrence of these neuropeptides was examined by immunofluorescence. Leu-Enk-like immunoreactivity was seen in nerve fibres associated with the epithelium, blood vessels and lingual salivary glands as well as in ganglionic cells within the tongue. Neuropeptide A-like immunoreactivity was found in nerve fibres associated with the epithelium, taste buds, blood vessels and lingual salivary glands. Cholecystokinin-like immunoreactivity was found in some nerve fibres around blood vessels as well as in ganglionic cells. The coexistence of these neuropeptides and substance P was also demonstrated in some nerve fibres and ganglionic cells within the tongue. Like substance P, these neuropeptides could be involved in blood flow regulation, salivation and as trophic factors for taste buds.

A postmortem study of senile amyloidosis of the tongue

In a postmortem study, the authors examined 50 tongue specimens from old people, in order to detect amyloid deposits. No single case could be detected.

Expression of hair-related keratins in a soft epithelium: subpopulations of human and mouse dorsal tongue keratinocytes express keratin markers for hair-, skin- and esophageal-types of differentiation

The dorsal surfaces of mammalian tongues are covered with numerous projections known as filiform papillae whose morphology varies in different species. Using a panel of monoclonal antibodies to keratins as probes, we have established that, in both human and mouse, the interpapillary epithelia express mainly the "esophageal-type" keratins, while the papillary epithelia express "skin-type" keratins as well as some keratins reacting with a monoclonal antibody (AE13) to hair keratins. The AE13-reactive proteins of the mouse were found to be very similar to those of authentic mouse hair keratins. However, the corresponding protein of human tongue appears to be different from all known human keratins. This protein has a MW of 51K; it is relatively acidic; it is sulfhydryl-rich, as revealed by iodoacetic acid-induced charge and apparent size shift; it shares an epitope with all the known acidic human hair keratins; and it is associated with keratin fibrils in vivo. This protein may therefore be regarded as a novel type I "hard" keratin. These data establish that mammalian dorsal tongue epithelia can be divided into at least three compartments that undergo mainly "esophageal-", "skin-" and "hair"-types of differentiation. Different keratin filaments, e.g., those of the esophageal- and hair-types, exhibit strikingly different degrees of lateral aggregation, which can potentially account for the different physical strength and rigidity of various cellular compartments. Our data also suggest the possibility that variations in papillary structure in human and mouse may arise from different spatial arrangements of specific keratinocytes, and/or from the expression of specialized hair-related keratins.

Immunocytochemical localization and biochemical analysis of alpha and beta keratins in the avian lingual epithelium

The alpha and beta keratins are found as 10-nm and 3-nm cytoplasmic filaments, respectively. While the alpha keratins are produced in essentially all vertebrate epithelia (Franke et al.: Exp. Cell Res., 116:429-445, 1978; Sun et al.: Proc. Natl. Acad. Sci. USA, 76:2813-2817, 1979), the beta keratins have been demonstrated only in specific epithelial tissues of birds and reptiles (Sawyer et al.: In: Biology of the Integument: Vertebrates. J. Bereiter-Hahn, A.G. Matoltsy, and K.S. Richards, eds. Springer-Verlag, Berlin, Vol. 2, pp. 194-238, 1986; Landmann: In: Biology of the Integument: Vertebrates. J. Bereiter-Hahn, A.G. Matoltsy, and K.S. Richards, eds. Springer-Verlag, Berlin, Vol. 2, pp. 150-187, 1986). Recently, Homberger and Brush (Zoomorphology, 106:103-114, 1986) have demonstrated that within the lingual epithelium of parrots, beta keratins are expressed exclusively in the anterior ventral region. While it is well established that epidermal-dermal interactions are important for the regional expression of the beta keratin genes in the avian scutate scales and feathers, little is known about the expression of beta keratins in other epithelial structures such as the tongue. We have used biochemical and immunocytochemical techniques to analyze the alpha and beta keratins of the lingual epithelium of the chick as an initial step in the characterization of this model system for developmental studies. We have found that alpha keratins are present throughout the lingual epithelium. The anterior ventral epithelium contains alpha keratin polypeptides characteristic of skin-type differentiation, while the epithelium of the dorsal and posterior ventral regions contains alpha keratin polypeptides characteristic of esophageal-type differentiation (O'Guin et al.: In: Current Topics in Developmental Biology: The Molecular and Developmental Biology of Keratins. A.A. Moscona and A. Monroy, eds. R.H. Sawyer, vol. ed. Academic Press, New York, Vol. 22, pp. 282-306, 1987). Beta keratins are produced only in the differentiated epithelial cells of the anterior ventral region of the tongue. Immunoelectron microscopy demonstrates that the alpha and beta keratins of the stratum intermedium and corneum of the anterior ventral region are found together in the large filament bundles characteristic of this region. The preexistence of the alpha keratins in the cells destined to produce beta keratins as well as the colocalization of these keratins in the filament bundles of these cells suggests that a functional relationship may exist between the alpha and beta keratins.

Expression pattern of two related cystic fibrosis-associated calcium-binding proteins in normal and abnormal tissues

This paper reports further study of the identity and function of a protein shown to be elevated in serum from cystic fibrosis (CF) patients and clinically normal heterozygotes. Monoclonal antibodies, specifically recognizing the tentatively named cystic fibrosis antigen (CFAg), were produced. Immunoaffinity purification of CFAg from several sources revealed two components: 11 x 10(3) and 14 x 10(3) Mr protein. cDNA clones corresponding to each protein have been isolated. Data-base comparisons of the deduced amino acid sequences suggest that both genes encode related but distinct calcium-binding proteins. We propose the name calgranulin A and B, for the 11 x 10(3) and 14 x 10(3) Mr components, respectively. It is clear from the assignment of the calgranulin genes to chromosome 1 that neither is the product of the mutant CF gene, which maps to chromosome 7. We have used the monoclonal antibodies to study the tissue distribution of the two proteins in a wide-ranging immunohistological survey. Where possible the pattern of expression was confirmed by RNA blot analysis. Strong calgranulin expression in granulocytes was confirmed. In addition to myeloid cells, a restricted subset of normal stratified squamous epithelia were found to be calgranulin-positive. These included tongue, oesophagus and buccal cells, the last of which has been shown to have altered calmodulin activity in CF patients. Using indirect alkaline phosphatase staining, tissue sections of lung, pancreas and skin (normally considered sites where the CF defect is expressed) were not calgranulin-positive. However, by indirect immunofluorescence, nasal polyp sections showed weak patchy calgranulin expression in some epithelial cells, and stronger, higher frequency expression when such cells were briefly cultured.(ABSTRACT TRUNCATED AT 250 WORDS)

Spatial map of salts and saccharides on dog tongue

Front and rear regions of dog tongue were tested for spatial heterogeneity with respect to monovalent chloride salts (NaCl, KCl, and NH4Cl) and sweet tastants (sucrose, D-glucose, and L-glucose) by placing them in Ussing chambers where the open-circuit potential, Voc, and short-circuit current, Isc, were measured. The responses of Voc and Isc to 0.5 M NaCl were greater in the front of the tongue than in the rear, whereas the responses of Voc and Isc to 0.5 M sucrose were greater in the rear of the tongue than in the front. These results are similar to those of published neurophysiological measurements from the chorda tympani nerve and thalamus. These data suggest that the spatial heterogeneities seen in higher taste centers are present in the isolated lingual epithelium where primary taste transduction events occur.

A cross-sectional study of the effects of alcohol on the protein profile of rat lingual epithelium

Sodium dodecyl sulphate-polyacrylamide slab gel electrophoresis, and subsequent densitometric analysis of rat lingual epithelial proteins, showed that for expression of previously reported protein alterations in the lingual epithelium of alcoholic rats, chronic alcohol consumption is required. Alterations in the levels of a high molecular-weight glycoprotein and a 30 k dalton protein in the rat lingual epithelium became significant following 60 days of alcohol consumption. Alterations in the levels of a 28 k dalton protein required more time to become significant. The results provided no evidence of a precursor/product relationship between the high molecular-weight glycoprotein and the two lower molecular-weight proteins.

Evidence for heterogeneity in the 160/165 × 10(3) Mr glycoprotein components of desmosomes

We have prepared both monoclonal and polyclonal antibody preparations directed against the 160/165 × 10(3) Mr glycoproteins (desmogleins) of bovine tongue epithelial desmosomes. The polyclonal antibody preparation recognizes desmosomes in a number of mouse tissues, e.g. mouse skin, heart, bladder and trachea, as determined by immunofluorescence microscopy. Furthermore, the polyclonal antibodies recognize polypeptide(s), present in the high salt, Triton-insoluble residues (‘cytoskeleton preparations’) of mouse skin, heart, bladder and trachea, which comigrate with the 160/165 × 10(3) Mr glycoproteins of bovine tongue epithelial desmosomes as determined by ‘Western’ immunoblotting. Conversely, the monoclonal 160/165 × 10(3) Mr antibody preparation recognizes desmosomes of stratified squamous epithelial tissues but not desmosomes in other tissue types. Moreover, whereas the monoclonal antibodies recognize 160/165 × 10(3) Mr polypeptides in mouse skin cell cytoskeletons they show no immunoreactivity with the cytoskeleton preparations of mouse bladder, trachea and heart following immunoblotting. These results suggest therefore that although there are conserved epitopes of the 160/165 × 10(3) Mr glycoproteins there are also epitopes of these molecules which vary from tissue to tissue. Double label immunofluorescence observations of cryostat sections of mouse skin using the monoclonal antibodies and antibodies directed against desmoplakin, a plaque component of desmosomes, reveal that the monoclonal antibodies do not recognize certain desmosomes in basal cells which are recognized by desmoplakin antibodies. Indeed, double label observations of cryostat sections of mouse skin using the monoclonal antibodies and human autoantibodies which react with hemidesmosomal components suggest that the monoclonal antibodies stain desmosomes located along the apical surfaces of basal cells but fail to recognize desmosomes along the lateral surfaces of these same cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta 2-microglobulin amyloidosis (AB2M) in patients undergoing long-term hemodialysis. A new type of amyloid

Amyloidosis has been increasingly recognized in association with renal failure and chronic hemodialysis. This report describes three patients who had long-term hemodialysis (between 7-18 years), in whom deposits developed of a new type of amyloid of beta 2-microglobulin origin. Beta 2-microglobulin amyloid (AB2M) was found in multiple organs, i.e., bone, subendocardium, gastrointestinal blood vessels, tongue, and carpal tunnel connective tissue. AB2M displayed characteristic amyloid features on conventional light and polarized microscopic examination after congo red staining. However immunostaining with anti-amyloid A protein, kappa, and lambda antisera were negative. The studied material reacted positively with beta 2-microglobulin antisera, identifying AB2M in all three cases. Ultrastructural study revealed an unusual curvi-linear fibrillar configuration. AB2M appears to be a new subtype of systemic amyloidosis secondary to renal failure and long-term hemodialysis.

Elevated concentrations of elements and abnormalities of neuromuscular junctions in tongue muscles of Down's syndrome

X-ray spectrometry was used to measure the concentrations of calcium, iron, copper and zinc in tongue muscles from patients with Down's syndrome (DS) undergoing partial glossectomy. Similar measurements on samples from autopsies served as controls. Electron microscopy was used to examine neuromuscular junctions. The calcium and copper were significantly elevated and correlated in DS while the iron and zinc showed little change. The copper increase is probably connected with the known high level of Zn-Cu superoxide dismutase (SOD), coded for by chromosome 21. (In DS there is a trisomy 21). The excess of SOD may interfere with free radicals needed for excitation-contraction coupling and may be instrumental in damaging junctional membranes. The high calcium may result from such membrane damage. It is suggested that neuromuscular junction pathology, either genetic or free radical induced, may cause the tongue weakness in DS.

The histology and carbohydrate histochemistry of the lingual glands in vervet monkeys

The lingual salivary glands of the vervet monkey were examined for the first time to establish their histological appearance and mucosubstance histochemistry. Sero-mucous and mucous glands are present. The mucin content of the serous glands is a neutral mucin, that of the mucus glands a carboxylated or sulphated sialomucin. The reason for the variation between cells was not established. Anterior lingual glands were not detected in any of the tongues examined.

Aminoalkylsilane-treated glass slides as support for in situ hybridization of keratin cDNAs to frozen tissue sections under varying fixation and pretreatment conditions

Attempts to investigate the cellular localization of keratin mRNAs by in situ hybridization with specific [35S]-labelled cDNA probes to mouse epithelia have been seriously impeded by the uncontrollable detachment of frozen tissue sections on conventionally coated glass slides (i.e. those coated with egg white, gelatin, collagen). Similarly, a variety of other coating and attachment devices have proved to be unsatisfactory or impracticable for large scale investigations. These difficulties were completely overcome and in situ hybridization was possible after a short immersion of the glass slides in a 2% solution of 3-aminopropyltriethoxysilane in acetone. This treatment provides the glass surface with aminoalkyl groups which are apparently able to react covalently with aldehyde or ketone functions of frozen tissue sections. The resulting firm adhesion of the sections enabled us to investigate the influence of different fixation and prehybridization procedures on the quality of the in situ hybridization. It was found that especially harsh prehybridization, involving hydrochloric acid, heat and proteinase K treatment, drastically reduces the morphological integrity of the sections, thus rendering a reliable assignment of the label difficult. In contrast, a mild prehybridization, consisting mainly of a rehydration of the sections in phosphate-buffered saline and equilibration in 0.1 M glycine, leaves the morphology intact and leads to a highly efficient and specific in situ hybridization.

Keratin proteins in human oral mucosa

We have examined the keratin proteins in normal human oral mucosa from 6 different regions including hard palate, buccal mucosa, tongue, gingiva and floor of the mouth. Urea-dithiothreitol extracts of EDTA separated epithelia were analysed by SDS-PAGE and immunoblotting. Eight samples from each region were investigated and showed very little individual variation in the keratin profile on Coomasie Blue-stained gels. The keratinizing hard palate and gingiva expressed identical patterns and resembled the pattern of epidermis from the flank region. The normally non-keratinizing buccal mucosa and the mucosa of the floor of the mouth expressed polypeptides distinctly different from those of the keratinizing epithelia and lacked the high molecular weight keratins. The dorsal surface of the tongue and the commissure region showed a pattern intermediate between keratinizing and non-keratinizing epithelia. The greater sensitivity of the immunoblotting technique revealed that the non-keratinizing epithelia synthesized one of the high molecular polypeptides and that the tongue produced all the bands found in keratinizing epithelia, but in very small quantities. There are, thus, distinct differences in the keratin expression of oral epithelia which are related to the pattern of keratinization assessed histologically.

Variation and frequency of cytokeratin polypeptide patterns in human squamous non-keratinizing epithelium

The squamous non-keratinizing epithelium of the human upper digestive tract was analyzed for keratin-like cytoskeletal proteins (cytokeratins) by both high resolution one- and two-dimensional gel electrophoresis. The Triton/high salt-insoluble portion of pure epithelial homogenates contains a number of SDS- and urea-extractable polypeptides, whose two-dimensional gel pattern (NEpHG/SDS) typically represents a defined subset of human cytokeratins. The cytoskeletal preparations of epithelial tissue samples obtained from different individuals were found to be uniform with respect to their content of cytokeratin polypeptides 55.0 kD/basic, 52.0 kD/acidic, and 49.0 kD/acidic. However, we have observed that four basic members of apparent molecular weight 60.0, 59.0, 56.5, and 56.0 kD occur at an inconstant rate. Consequently, the cytokeratin polypeptide patterns appeared highly variable as a result of the presence of constant plus compositionally different subsets of inconstant members. From the analysis of cytoskeletal portions of more than 300 individual tissue samples we demonstrate eight different keratin-like polypeptide patterns including their frequencies and propose the existence of no more than nine. These, most probably, encompass all the possible inter-individual variations to which the cytokeratins of this type of epithelium will combine for forming intermediate-sized filaments in vivo. We furthermore hypothesize that the observed variation of cytokeratin patterns may reflect a polymorphism of genes coding for the variable keratin-like polypeptide members.

Different patterns of cytokeratin expression in the normal epithelia of the upper respiratory tract

The distribution and type of cytokeratins present in the normal human epithelia of the nasopharynx, oropharynx, tongue, palatine tonsil, epiglottis, vocal cord, and laryngeal ventricle were studied using immunohistochemical techniques and by gel electrophoresis of cytoskeletal proteins microdissected from frozen tissues. Noncornifying stratified epithelia covering the oropharynx, tongue, surface of the palatine tonsil, pharyngeal surface of the epiglottis, and vocal cord were all found to contain cytokeratins nos. 4, 5, 6, 13, 14, and 15, together with minor amounts of cytokeratin no. 19, i.e., a pattern similar to that previously reported for esophageal epithelium. The immunohistochemical reaction with KA4, an antibody specific for cytokeratins nos. 14, 15, 16, and 19, revealed reactivity confined to the basal epithelial cells of the tongue, oropharynx, pharyngeal epiglottis, and two out of five samples of vocal cords. This same antibody reacted with the entire thickness of three out of the five true vocal cords which were shown by gel electrophoresis to also contain cytokeratins nos. 16 and 17. Gel electrophoresis revealed that the pseudostratified columnar epithelium covering the laryngeal ventricle was more complex, in that it contained cytokeratins nos. 5, 13, 14, 15, and 17, which are typical of stratified epithelia, as well as cytokeratins nos. 7, 8, 18, and 19, which are characteristic of simple epithelia. This pattern is similar to that found in bronchial epithelium. The laryngeal surface of the epiglottis exhibited cytokeratins nos. 4, 5, 7, 8, 13, 14, 15, 17, 18, and 19, i.e., a pattern combining features of both esophageal- and bronchial-type epithelia. The reaction of these epithelia containing columnar cells with antibody RGE-53, which is specific for cytokeratin no. 18, revealed a staining reaction confined to the superficial columnar cells, whereas KA1 stained only the basal cells of these epithelia. The results of our study make it possible to distinguish two types of noncornifying stratified squamous epithelium, namely the 'esophageal type' which covers the tongue, oropharynx, and pharyngeal surface of the epiglottis, and another type which overlies the vocal cords and the transitional zone between the pharyngeal and laryngeal surfaces of the epiglottis. Furthermore, there appear to be variants of pseudostratified columnar epithelium, i.e., the usual bronchial type lining the laryngeal ventricle, and a type with a thicker subcolumnar cell compartment that is found on the laryngeal surface of the epiglottis. The patterns of expression of cytokeratins in the respiratory tract are compared with those of other epithelia.

Significance of two desmosome plaque-associated polypeptides of molecular weights 75 000 and 83 000

Isolated desmosomes from bovine epidermis contain two major polypeptides of mol. wts. 75 000 (D6) and 83 000 (D5) which, like the desmoplakins of mol. wt. greater than 200 000, are associated with the insoluble desmosomal plaque structure. We have characterized these two polypeptides and examined their significance by peptide map comparisons and translation of bovine epidermal mRNA in vitro. Polypeptide D5 is different from polypeptide D6 by its apparent mol. wt., its isoelectric pH (approximately 6.35, whereas D6 is a basic polypeptide isoelectric at pH approximately 8.5) and its peptide map. By all these criteria desmosomal polypeptides D5 and D6 are also different from cytokeratins, desmoplakins and the glycosylated desmosomal proteins. Both polypeptides are synthesized from different mRNAs separable by gel electrophoresis on agarose: mRNA coding for polypeptide D5 is approximately 3500 nucleotides long, that for D6 is significantly shorter (estimated to 3050 nucleotides), and both contain relatively large proportions of non-coding sequences. The translational products of these mRNAs co-migrate, on two-dimensional gel electrophoresis, with the specific polypeptides from bovine epidermis, indicating that they are genuine polypeptides and are not the result of considerable post-translational processing or modification of precursor molecules. The cell and tissue distribution of these two cytoskeletal proteins and possible functions are discussed.

Light microscopic detection of sugar residues in glycoconjugates of salivary glands and the pancreas with lectin-horseradish peroxidase conjugates. I. Mouse

Mouse salivary glands and pancreases were stained with a battery of ten horseradish peroxidase-conjugated lectins. Lectin staining revealed striking differences in the structure of oligosaccharides of stored intracellular secretory glycoproteins and glycoconjugates associated with the surface of epithelial cells lining excretory ducts. The percentage of acinar cells containing terminal alpha-N-acetylgalactosamine residues varied greatly in submandibular glands of 30 male mice, but all submandibular acinar cells contained oligosaccharides with terminal sialic acid and penultimate beta-galactose residues. The last named dimer was abundant in secretory glycoprotein of all mucous acinar cells in murine sublingual glands and an additional 20-50% of these cells in all glands contained terminal N-acetylglucosamine residues. In contrast, terminal alpha-N-acetylgalactosamine was abundant in sublingual serous demilune secretions. Serous acinar cells in the exorbital lacrimal gland, posterior lingual gland, parotid gland and pancreas exhibited a staining pattern unique to each organ. In contrast, the apical cytoplasm and surface of striated duct epithelial cells in the submandibular, sublingual, parotid and exorbital lacrimal gland stained similarly. A comparison of staining with conjugated lectins reported biochemically to have very similar carbohydrate binding specificity has revealed some remarkable differences in their reactivity, suggesting different binding specificity for the same terminal sugars having different glycosidic linkages or with different penultimate sugar residues.

Alphafoetoprotein uptake by cloned cell lines derived from a nickel-induced rat rhabdomyosarcoma

Rat, mouse, pig and chicken alphafoetoproteins (AFP), rat serum albumin and egg albumin, or their fluoresceinated conjugates were added to cultures of several cloned cell lines isolated from a nickel-induced rat rhabdomyosarcoma. The intracellular uptake of assayed proteins was revealed by the indirect immunoperoxidase technique and/or by direct fluorescence microscopy. All the clones examined bound AFP, and all but one internalized the protein. The protein localized in the membrane and the cytoplasm, as well as along straight processes interconnecting cells. Nuclei were always AFP negative. The protein uptake of fluoresceinated conjugates of AFP and serumalbumin was already visible 15 min after incubation and progressed with time to reach a plateau 4-5 h later. Ultrastructural radioautographs of cells incubated with [3H]-AFP (rat) showed protein accumulation in several organelles and particularly in lipid droplets. Parallel to these observations, the intracellular presence of AFP within myofibrillar structures was demonstrated in tongue sections of rat foetuses and neonates. The results presented here provide experimental evidence of the reappearance in cloned cell lines derived from a primary rhabdomyosarcoma of a property pertaining to foetal striated muscle.

The substance P content of peripheral tissues in several mammals

Levels of substance P immunoreactivity (SPI) were determined in several skin and mucosal areas, in parts of the sympathetic nervous system, the urinary, biliary and respiratory systems of cats, rabbits and guinea-pigs, and in various skin and mucosal areas of humans by radioimmunoassay. Salient findings are (1) The general distribution pattern of SPI in rabbits was similar to that in rodents. (2) The highest SPI tissue levels were found in the sympathetic nervous system, notably in guinea-pigs. (3) The guinea-pig also had the highest SPI levels in ureter, urinary bladder and bile duct. (4) The aorta, pulmonary artery and portal vein of the rabbit contained very low amounts of SPI, the concentration in the carotid sinus being several fold higher. (5) Skin SPI content was generally highest in the cat, especially in the hindpaw-pad, and lowest in abdominal and back skin. (6) SPI levels found in postmortem human skin and mucosal samples are comparable to those found in other mammals. The observations are discussed in view of the sensory innervation of the various tissues.

Work in progress: NMR anatomy of the larynx and tongue base

The normal anatomy of the larynx and base of the tongue as seen on nuclear magnetic resonance (NMR) images was studied. Scans of normal volunteers were obtained using a 3.5 kilogauss (0.35 T) superconductive magnet and a 3.0 kilogauss (0.3 T) permanent magnet. The NMR images were compared with images obtained by CT and with anatomical sections of these regions. Although resolution is not comparable to that seen on scans obtained with modern CT equipment, there are some advantages to NMR imaging. These include availability of multiple projections, ease of identifying blood vessels and differentiating them from lymph nodes, and the possibility of improved tissue specificity.