The soft palate is an important site of adaptation for transmissible influenza viruses.

Influenza A viruses pose a major public health threat by causing seasonal epidemics and sporadic pandemics. Their epidemiological success relies on airborne transmission from person to person; however, the viral properties governing airborne transmission of influenza A viruses are complex. Influenza A virus infection is mediated via binding of the viral haemagglutinin (HA) to terminally attached α2,3 or α2,6 sialic acids on cell surface glycoproteins. Human influenza A viruses preferentially bind α2,6-linked sialic acids whereas avian influenza A viruses bind α2,3-linked sialic acids on complex glycans on airway epithelial cells. Historically, influenza A viruses with preferential association with α2,3-linked sialic acids have not been transmitted efficiently by the airborne route in ferrets. Here we observe efficient airborne transmission of a 2009 pandemic H1N1 (H1N1pdm) virus (A/California/07/2009) engineered to preferentially bind α2,3-linked sialic acids. Airborne transmission was associated with rapid selection of virus with a change at a single HA site that conferred binding to long-chain α2,6-linked sialic acids, without loss of α2,3-linked sialic acid binding. The transmissible virus emerged in experimentally infected ferrets within 24 hours after infection and was remarkably enriched in the soft palate, where long-chain α2,6-linked sialic acids predominate on the nasopharyngeal surface. Notably, presence of long-chain α2,6-linked sialic acids is conserved in ferret, pig and human soft palate. Using a loss-of-function approach with this one virus, we demonstrate that the ferret soft palate, a tissue not normally sampled in animal models of influenza, rapidly selects for transmissible influenza A viruses with human receptor (α2,6-linked sialic acids) preference.

Basal cell adenocarcinoma arising from the minor salivary gland in the soft palate: a case report.

Basal cell adenocarcinomas (BCACs) of the oral minor salivary gland are very rare neoplasms. We report on an 86-year-old woman with BCAC arising from the minor salivary gland in the soft palate. Histologically, the tumor was located in the submucosa and showed microinvasion into the adjacent soft tissue without encapsulation. It contained tiny tumor islands with solid and tubular patterns, as well as myxoid stroma. The neoplastic cells were basaloid cells and were composed of large pale cells and small dark cells. They were positive for alpha-smooth muscle actin, cytokeratin 14, and vimentin in the periphery of the tumor island, showing a myoepithelial differentiation. The myxoid stroma was positive for alcian blue and colloidal iron. Apical membranes of the neoplastic cells were positive for MUC1 and CEA. The present case is the 14th documented case of oral BCAC (the fifth case of palatal BCAC).

Sialadenoma papilliferum: immunohistochemical study.

Sialadenoma papilliferum (SP) is a rare benign tumour of salivary gland origin, which has been included among the ductal papillomas in the latest classification of tumours by the World Health Organisation. Two SP from the minor salivary gland of the palate of middle age patients were presented and studied by immunohistochemical. Our results showed presence of cytokeratins (CKs) 13, 14, 7, 8, 19 and absence of vimentin and smooth muscle actin. This immunoprofile is similar to the excretory duct of salivary gland.

Morphological characterization of the levator veli palatini muscle in children born with cleft palates.

OBJECTIVE: The aim of this study was to analyze, morphologically and biochemically, one of the soft palate muscles, the levator veli palatini (LVP), in children born with cleft palate. SUBJECTS AND METHODS: Biopsies were obtained from nine male and three female infants in connection with the early surgical repair of the hard and soft palate. Samples from five adult normal LVP muscles were used for comparison. The muscle morphology, fiber type and myosin heavy chain (MyHC) compositions, capillary supply, and content of muscle spindles were analyzed with different enzyme-histochemical, immunohistochemical, and biochemical techniques. RESULTS: Compared with the normal adult subjects, the LVP muscle from the infantile subjects with cleft had a smaller mean fiber diameter, a larger variability in fiber size and form, a higher proportion of type II fibers, a higher amount of fast MyHCs, and a lower density of capillaries. No muscle spindles were observed. Moreover, one-third of the biopsies from the infantile subjects with cleft LVP either lacked muscle tissue or contained only a small amount. CONCLUSIONS: The LVP muscle from children with cleft palate has a different morphology, compared with the normal adult muscle. The differences might be related to different stages in maturation of the muscles, changes in functional demands with growth and age, or a consequence of the cleft. The lack of contractile tissue in some of the cleft biopsies offers one possible explanation to a persistent postsurgical velopharyngeal insufficiency in some patients, despite a successful surgical repair.

Development and maturation of taste buds of the palatal epithelium of the rat: histological and immunohistochemical study.

Palatal taste buds are intriguing partners in the mediation of taste behavior and their spatial distribution is functionally important for suckling behavior, especially in the neonatal life. Their prenatal development has not been previously elucidated in the rat, and the onset of their maturation remains rather controversial. We delineated the development and frequency distribution of the taste buds as well as the immunohistochemical expression of alpha-gustducin, a G protein closely related to the transduction of taste stimuli, in the nasoincisor papilla (NIP) and soft palate (SP) from the embryonic day 17 (E17) till the postnatal day 70 (PN70). The main findings in the present study were the development of a substantial number of taste pores in the SP of fetal rats (60.3 +/- 1.7 out of 122.8 +/- 5.5; mean +/- SD/animal at E19) and NIP of neonatal rats (9.8 +/- 1.0 out of 44.8 +/- 2.2 at PN4). alpha-gustducin-like immunoreactivity (-LI) was not expressed in the pored taste buds of either prenatal or newborn rats. The earliest expression of alpha-gustducin-LI was demonstrated at PN1 in the SP (1.5 +/- 0.5 cells/taste bud; mean +/- SD) and at PN4 in the NIP (1.4 +/- 0.5). By age the total counts of pored taste buds continuously increased and their morphological features became quite discernible. They became pear in shape, characterized by distinct pores, long subporal space, and longitudinally oriented cells. Around the second week, a remarkable transient decrease in the total number of taste buds was recorded in the oral epithelium of NIP and SP, which might be correlated with the changes of ingestive behaviors. The total counts of cells showing alpha-gustducin-LI per taste bud gradually increased till the end of our investigation (14.1 +/- 2.7 in NIP and 12.4 +/- 2.5 in SP at PN70). We conclude that substantial development of taste buds began prenatally in the SP, whereas most developed entirely postnatal in the NIP. The present study provides evidence that the existence of a taste pore which is considered an important criterion for the morphological maturation of taste buds is not enough for the onset of the taste transduction, which necessitates also mature taste cells. Moreover, the earlier maturation of palatal taste buds compared with the contiguous populations in the oral cavity evokes an evidence of their significant role in the transmission of gustatory information, especially in the early life of rat.

Epithelial-connective tissue boundary in the oral part of the human soft palate.

The papillary layer of the oral part of the human soft palate was studied in 31 subjects of different age by means of histological, immunohistochemical and scanning electron microscopical methods. For scanning electron microscopy a new maceration method was introduced. Results determine epithelial thickness, height and density of connective tissue papillae and their 3-dimensional architecture inside the lining epithelium as well as the collagenous arrangement of the openings of the glandular ducts. The individual connective tissue papillae of the soft palate are compared with the connective tissue boundary on the other side of the oral cavity. The connective tissue plateaux carrying a variable number of connective tissue papillae were found to be the basic structural units of the papillary body. The function of the epithelial-connective tissue interface and the extracellular matrix arrangement in the lamina propria are discussed in order to promote the comparability of normal with pathologically altered human soft palates.

Distribution of two VIP-related peptides, helospectin and pituitary adenylate cyclase activating peptide (PACAP), in the human upper respiratory system.

Helospectin (HS) and pituitary adenylate cyclase activating peptide (PACAP) are newly discovered peptides isolated from the salivary gland venom of the lizard Heloderma horridum and the ovine hypothalamus, respectively. They show chemical similarities to vasoactive intestinal polypeptide (VIP), appear to have similar functions and are present in gut, brain, lung, male and female genitourinary tract. In the present study, the distribution of the helospectin and PACAP-27 in the human upper respiratory system was investigated using indirect immunofluorescence and electron-microscopical ABC-pre-embedding methods. Immunohistochemistry revealed helospectin-like (HS-LI) and PACAP-like (PACAP-LI) immunoreactivity in nerve fibers in human nasal, the larynx (vocal cord, ventricular fold, epiglottis), the tongue and the soft palate mucosa. Helospectin-LI and PACAP-LI containing nerve fibers were mainly found in close association to blood vessels and glandular structures. Colocalization studies carried out by application of double immunofluorescence showed that HS and/(or) PACAP-LI coexist with VIP in apparently the same nerve fibers in the upper respiratory system, although single nerve fibers seem to exclusively express helospectin. The localization patterns of helospectin and PACAP-LI in the human upper respiratory system suggests their possible involvement in the regulation of secretory activities and local blood flow.

Regulatory peptides in the human soft palate.

The distributions of vasoactive intestinal polypeptide, peptide, histidine methionine, helospectin, neuropeptide Y and its C-flanking peptide, substance P and calcitonin gene-related peptide were studied in the human soft palate using immunocytochemical techniques. Peptide-containing nerve fibers were found to form a dense network around glandular acini, excretory ducts and blood vessels, as well as beneath and within the epithelium. Chromogranin A, bombesin-flanking peptide and calcitonin gene-related peptide immunoreactivities were detected in endocrine-like cells located in excretory ducts.

Regulatory peptides and general neuroendocrine markers in human nasal mucosa, soft palate and larynx.

Various peptide immunoreactivities in the respiratory system have been reported, indicating complex physiological mechanisms. There is only little information on the upper respiratory system of man. The present study was carried out to demonstrate regulatory peptides in the nasal mucosa, larynx (vocal cords and ventricular folds) and soft palate of man using highly efficient immunocytochemical methods. In addition, some peptide immunoreactivities were measured by use of radioimmunoassay (RIA). Using indirect immunofluorescence and immunogold-silver staining (IGSS) with silver acetate autometallography, a series of peptides could be detected, including vasoactive intestinal polypeptide (VIP), peptide histidine methionine (PHM), galanin, calcitonin gene-related peptide (CGRP), substance P, neuropeptide tyrosine (NPY), C-flanking peptide of NPY (CPON) and somatostatin. In addition, antibodies to protein gene-product (PGP) 9.5, neuron-specific enolase (NSE), S-100, PHE-5 and neurofilament proteins gave positive reactions in tissue sections. Using RIA, CGRP, substance P, and neurokinin A were measured. Our results demonstrate a complex network of regulatory peptide-containing nerve fibers and the possible existence of endocrine cells regulating various functions of the upper respiratory system, which need to be further investigated.