Salivary Epithelium Research Articles

Lysophosphatidic acid cooperates with EGF in inducing branching morphogenesis of embryonic mouse salivary epithelium

Epithelial morphogenesis is supported by diffusible growth factors and by nondiffusible cell substrata, such as laminin and fibronectin. When embedded in a laminin-rich basement-membrane substratum, embryonic mouse submandibular epithelium undergoes cell proliferation and branching morphogenesis in response to epidermal growth factor (EGF) in mesenchyme-free culture but not in serum-free medium. In this study, we sought to identify the biologically active factor in serum. As this factor was heat-stable and trypsin-resistant, the lipid fraction was analyzed. Horse serum was fractionated by ethanol extraction, Folch partition with chloroform-methanol-water, and high-performance liquid chromatography, and we tested the branch-inducing activity of each fraction. We also analyzed the partially purified fraction with a mass spectrometer, indicating that the active fraction largely consisted of lysophosphatidyl-hexose. Finally we identified the molecule as lysophosphatidic acid (LPA), because, whereas lysophosphatidyl-inositol had only a slight branch-inducing activity, its relevant LPA fully substituted for serum and induced branching morphogenesis in cooperation with EGF. LPA receptor genes were expressed in submandibular epithelial cells. DNA-synthesizing cells were abundant only when cultured in the presence of both EGF and LPA, but not either singly.

Cystic lesion of the parotid following drug‐induced toxic epidermal necrolysis (Lyell's syndrome)

A 32-year-old woman developed a unilateral cyst of the duct of parotid gland 4 months after severe oral involvement of drug-induced toxic epidermal necrolysis (TEN). The pathomechanism leading to the TEN epidermal destruction had presumably involved the salivary epithelium as well, leading to the development of the cystic lesion. The patient had low serum lipase levels, but high serum amylase levels at the time of TEN. These serological markers could represent a clue for the risk of developing cystic lesions of the large salivary glands following TEN.

Sialadenoma papilliferum of the buccal mucosa: A case report of a rare localization and review of the literature

AbstractSialadenoma papilliferum is a rare, benign salivary gland tumor which most commonly arises in the palate. It is an exophytic papillary proliferation that involves mucosal surface or epidermis and salivary duct epithelium. Approximately 11% of sialadenoma papilliferum cases were reported in the buccal mucosa. The sialadenoma papilliferum is often misinterpreted as squamous papilloma by surgeons.In this case, sialadenoma papilliferum located in the buccal mucosa of a 64-year-old man is reported. The mass was asymptomatic, slow-growing, movable and was clinically similar to the lipoma. A surgical excision was performed and after 22 months there has been no recurrence.

Antisense inhibition of transglutaminase 2 affects development of mouse embryo submandibular gland in organ culture

Tissue transglutaminase (TGase 2) has been implicated in numerous cellular functions, i.e., apoptosis, differentiation, extracellular matrix protein cross-linking and organogenesis. Earlier report of the strong transient expression of TGase 2 localized at the anchoring sites of muscle bundles of human embryo and recent findings of a similar transient expression of the TGase 2 in the salivary myoepithelial cells of mouse embryo indicated a definitive role of TGase 2 in the cytodifferentiation of myoepithelial cells. To understand functional role(s) of TGase 2 in the organogenesis of salivary gland, antisense inhibition of TGase 2 expression was performed in the organ culture of mouse embryo submandibular gland. The antisense of TGase 2 transfection tested using oral keratinocyte cell line, KB cells, elicited significant inhibition of cellular transglutaminase expression. The same antisense treatment of submandibular glands in organ culture also resulted in the suppression of cellular TGase 2 expression as indicated by weak immunoreaction against anti-TGase 2 in the myoepithelial cells of submandibular glands in contrast to strong reaction in those of the normal and sense-treated glands. Antisense to TGase 2 treatment induced retarded growth of salivary epithelium in 1 week and severe aberrant growth of salivary ducts and acini in 2 weeks and also expression of apoptotic inducer, Bax specifically localized in the myoepithelial cells, suggesting apoptotic state of myoepithelial cells. These data suggest that the antisense inhibition of TGase 2 expression affects the cytodifferentiation of ductal cells and myoepithelial cells, and resulted in severe retardation of tubuloalveolar structure formation of salivary gland.

Transglutaminase 2 expression in the salivary myoepithelial cells of mouse embryo

Earlier a strong transient expression of transglutaminase 2 (TGase 2) localized at the anchoring sites of muscle bundles in human embryo was observed. In this study, we report a similar transient expression of the TGase 2 in the salivary myoepithelial cells of mouse embryo by immunohistochemistry, RNA in situ hybridisation, and RT-PCR. From 35 submandibular glands of mouse embryos and postnatal mice, a consistent expression of TGase 2 in the myoepithelial cells via a stage-specific manner was identified by mono-clonal antibody to TGase 2 immunostaining. A similar expression pattern of TGase 2 in the myoepithelial cells was also observed by RNA in situ hybridisation analysis. The expression of TGase 2 in the salivary epithelium and mesenchyme during the prenatal 14.5-15.5 days was found minimally diffusely spread and became intensely focalised in the myoepithelial cells of salivary acini and ducts during the prenatal 16.5-18.5 days but thereafter gradually decreased until postnatal 7 days and remained weak in postnatal 3 weeks. Such transient rise and fall expressions of TGase 2 were also found with the sequential amount of RT-PCR products during the same period. The alpha-smooth muscle actin (alpha-SMA) as a positive control in the myoepithelial cells of mouse submandibular glands was consistently expressed during the prenatal and postnatal period. These results of transient expression of TGase 2 in the myoepithelial cells coincided with the formation of the dendritic basket structure in the periphery of acini and ducts, suggest a possible catalytic role of transglutaminase in a newly formed cellular matrixes during the cytodifferentiating stage of mouse prenatal and neonatal submandibular glands.

Oral carcinoma in situ with extensive dendritic melanocytic colonization

A 49-year-old, well nourished, well developed, African-American man presented by referral to the oral and maxillofacial surgeon's office for the evaluation and management of a 2 × 2-cm deeply pigmented lesion with an erythematous border located in his left soft palatal mucosa. The lesion was superficial but contained a small area of central ulceration. Review of his past medial history was significant for peripheral vascular disease and diabetes. Review of his social history revealed a 30-packs/year history of smoking and daily consumption of alcoholic beverages. An incisional biopsy showed carcinoma in situ with extensive dendritic melanocytic colonization. The dysplastic changes also focally involved salivary gland ductal epithelium. Immunohistochemical staining with anti-HMB45 and anti-S-100 protein antibodies clearly delineated the dendritic melanocytes and melanocytic processes. Staining with broad spectrum cytokeratin was strong and diffuse. An outside expert was consulted and agreed with our interpretation. The lesion was excised with clear margins and the resection specimen showed findings identical to the biopsy. Melanocytic colonization is a well recognized occurrence in various primary and metastatic tumors including oral and cutaneous squamous cell carcinoma, but the incidence remains low and the significance of such finding remains to be determined. Various theories have been proposed to explain the proliferation and colonization of melanocytes, including the liberation of cytokines, growth factors, or other unknown factors by cancer cells. It has been suggested also that in ulcerated lesions, the presence of the melanocytes may represent cells that migrated into the existing lesion. In this case report, we review the literature and theories of etiology. The keratinocyte-melanocyte relationship is also investigated in this interesting entity.

Effect of hyperglycaemia on glucose concentration of human nasal secretions.

Glucose is not detectable in airways secretions of normoglycaemic volunteers, but is present at 1-9 mmol x l(-1) in airways secretions from people with hyperglycaemia. These observations suggest the existence of a blood glucose threshold at which glucose appears in airways secretions, similar to that seen in renal and salivary epithelia. In the present study we determined the blood glucose threshold at which glucose appears in nasal secretions. Blood glucose concentrations were raised in healthy human volunteers by 20% dextrose intravenous infusion or 75 g oral glucose load. Nasal glucose concentrations were measured using modified glucose oxidase sticks as blood glucose concentrations were raised. Glucose appeared rapidly in nasal secretions once blood glucose was clamped at approx. 12 mmol x l(-1) ( n =6). On removal of the clamp, nasal glucose fell to baseline levels in parallel with blood glucose concentrations. An airway glucose threshold of 6.7-9.7 mmol x l(-1) was identified ( n =12). In six subjects with normal glucose tolerance, blood glucose concentrations rose above the airways threshold and nasal glucose became detectable following an oral glucose load. The presence of an airway glucose threshold suggests that active glucose transport by airway epithelial cells normally maintains low glucose concentrations in airways secretions. Blood glucose exceeds the airway threshold after a glucose load even in people with normal glucose tolerance, so it is likely that people with diabetes or hyperglycaemia spend a significant proportion of each day with glucose in their airways secretions.

Regulation of cadherin junctions during mouse submandibular gland development.

Submandibular gland (SMG) development involves branching morphogenesis of the salivary epithelium into the surrounding mesenchyme, accompanied by proliferation and differentiation of immature salivary cells along acinar and ductal cell lineages. During development, salivary cell sorting and cell-cell adhesion are likely to be directed by cadherin adhesion receptors. We show that two classic cadherins, N- and E-cadherin, participate in SMG development. Early in embryonic morphogenesis, both cadherins displayed diffuse staining with regionalized localization to cell-cell borders. At this stage, significant pools of N- and E-cadherins were Triton-soluble, suggesting that fractions of these molecules were not localized to stable junctional complexes associated with the actin cytoskeleton. With cytodifferentiation, cadherins became progressively Triton-insoluble, and this correlated with their organization at cell-cell interfaces. In the cytodifferentiated SMG, N-cadherin was absent, whereas E-cadherin remained at cell-cell interfaces. Early in morphogenesis, beta-catenin was also primarily Triton-soluble, and its association with the actin cytoskeleton and localization to the adherens junctions increased with cytodifferentiation. Greater recruitment of cadherins and beta-catenin to cell-cell borders was paralleled by changes in membrane association of two Rho GTPases, Cdc42 and RhoA. N-cadherin was detected only at early stages of postnatal development, whereas E-cadherin and beta-catenin became progressively Triton-insoluble during differentiation. Our results indicate that N-cadherin functions transiently in SMG development. On the other hand, E-cadherin and beta-catenin appear to play different roles during tissue organization and cytodifferentiation. In early morphogenesis, E-cadherin and beta-catenin are likely to participate in SMG remodeling, whereas during cytodifferentiation, they form stable cell-cell contacts, and may collaborate with Rho GTPases in the establishment and maintenance of salivary cell polarity.

CD40 on salivary gland epithelial cells: high constitutive expression by cultured cells from Sjögren’s syndrome patients indicating their intrinsic activation

CD40 has been identified in an expanding list of haematopoietic and non-haematopoietic cells and has received an increased interest based on its role in a variety of cell-mediated responses and its potential to participate in the pathogenesis of chronic inflammatory disorders. Sjögren's syndrome (SS) is an autoimmune exocrinopathy, which is characterized by chronic lymphocytic infiltration of exocrine glands and aberrant activation of epithelial tissues. We studied the expression of CD40 protein in cultured non-neoplastic salivary gland epithelial cell (SGEC) lines as well as in minor SG biopsies obtained from 17 SS patients and 12 controls. Immunocytochemical and flow cytometric analyses had revealed the occurrence of constitutively expressed CD40 molecules on the surface of long-term cultured SGEC lines, which could be further induced by interferon-gamma (IFN-gamma) and IL-1beta cytokines, but not tumour necrosis factor-alpha (TNF-alpha), IL-4, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF) or IFN-alpha. Triggering of SGEC through CD40 enhanced the surface expression of the adhesion molecule intercellular adhesion molecule-1 (ICAM-1)/CD54, but not MHC class I and class II (HLA-DR) molecules. Spontaneous CD40 expression was significantly higher in SGEC lines derived from SS patients, compared with controls (P < 0.001), which is suggestive of their intrinsically activated status. In SG biopsies, CD40 was constitutively expressed by lymphocytes, ductal epithelial cells and endothelial cells but not by other glandular cell types, such as acinar cells, myoepithelial cells and fibroblasts. In addition, CD40L staining was also detected in 30--50% of the infiltrating lymphocytes in the biopsies of SS patients. Our findings indicate the immunoregulatory potential of SGEC and lend further support to a model of intrinsic activation in salivary epithelia in SS, whereby these cells actively participate in the induction and maintenance of lymphocytic infiltrates of patients.

Activated caspase 3 and cleaved poly(ADP-ribose)polymerase in salivary epithelium suggest a pathogenetic mechanism for Sjögren's syndrome.

Apoptosis is an organized energy-dependent process of cellular self-destruction carried out by proteolytic enzymes such as the caspases. These enzymes may play a role in epithelial cell apoptosis in Sjögren's syndrome (SS). A classical caspase substrate is poly(ADP-ribose)polymerase (PARP), a DNA repair enzyme. To elucidate the molecular mechanisms responsible for salivary gland dysfunction in SS, we studied the expression of caspase and PARP in SS salivary gland biopsies. The presence of activated caspases (caspases 3 and 9) and cleaved PARP (85 kDa) in SS biopsies was demonstrated by immunohistochemistry using specific polyclonal antibodies. Initial studies performed with an antibody reagent that recognizes both active and inactive forms of caspase 3 identified this enzyme in SS salivary ductal and acinar cells. Activated caspase 3 and cleaved PARP were strongly expressed in ductal and acinar cells in SS salivary glands (13/15). Ductal and acinar cells from normal salivary glands (n=5) stained with less intensity compared with SS tissue. Staining for activated caspase 9 was negative in all samples. Likewise, infiltrating lymphocytes were negative for caspase 3, caspase 9 and cleaved PARP. This study shows that caspase 3 is important in the salivary dysfunction of SS, while caspase 9 appears not to be involved.

Activation of epithelial and myoepithelial cells in the salivary glands of patients with Sjögren's syndrome: high expression of intercellular adhesion molecule-1 (ICAM.1) in biopsy specimens and cultured cells.

ICAM.1 (CD54) is a surface protein expressed on epithelial and other nonhematopoietic cells upon activation and is known to play an important role in the stimulation of T cells by the provision of cellular adhesion and costimulatory support. Sjogren's syndrome (SS) is an autoimmune exocrinopathy, which is characterized by chronic lymphocytic infiltration of exocrine glands and aberrant activation of epithelial tissues. To address the contribution of ICAM.1 in the pathogenesis of SS, the expression of this protein was studied by immunohistochemistry and flow cytometry in minor salivary gland (SG) biopsies as well as in cultured SG epithelial cell (SGEC) lines obtained from 18 SS patients and 16 controls. In biopsies from SS patients (but not controls), strong ICAM.1 was expressed by infiltrating mononuclear cells (52%) and by a significant proportion of periacinar myoepithelial cells (18%). In addition, a patchy pattern of moderate ICAM.1 expression was detected in 31% of ductal epithelia of SS patients. These ICAM.1-expressing epithelial and myoepithelial cells were observed throughout glandular tissues and were not confined in areas proximal to lymphoid infiltrates. In support to an intrinsic activation profile of SGEC in SS, long-term cultured non-neoplastic SGEC lines derived from SS patients displayed significantly upregulated spontaneous expression of ICAM.1, compared to controls (P < 0.05). The high expression of ICAM.1 protein by the salivary epithelium of SS patients is likely suggestive of its important role in the pathogenesis of the disorder. Further, our results support a model of intrinsic activation of salivary epithelial and myoepithelial cells in SS, whereby these cells actively participate in the induction and maintenance of lymphocytic infiltrates of patients.

Tissue Engineering of Human Salivary Gland Organoids

Radiation therapy for malignant head and neck tumours is mainly responsible for inadvertent damage of the salivary glands. Xerostomia is the major symptom of this condition, with consequent mucositis, dental caries, dysphagia and nutritional deficits. At present there is no routine treatment for radiation-induced salivary dysfunction. Based on the principles of tissue engineering, this study presents a new experimental concept for reconstituting salivary gland function after radiation therapy for head and neck cancer. Human parotid cells were cultured with two different types of commercially available microcarriers - Cytodex 3 and Cytopore 1 - for up to 3 weeks in vitro . Cultures were controlled daily by means of inverted microscopy. Medium samples were tested for alpha-amylase, tissue polypeptide antigen (TPA) and S100 in order to control parotid cell function in vitro . The vitality of the cells was investigated by in vitro staining with erythrosine. Immunocytochemical analysis for amylase and cytokeratin was performed in order to confirm epithelial character and maintain acinar cell type. Parotid gland cells could be cultured in a differentiated and vital state on both types of microcarriers for up to 3 weeks. Almost all of the cultured cells exhibited immunoreactivity for cytokeratin. High concentrations of TPA, a specific marker for salivary duct epithelium, indicated persistent differentiation of this cell type in vitro . Positivity for amylase was detectable in 20-45% of cells growing on the microcarriers, and especially on Cytodex 3. Decreasing amylase levels in the culture medium indicated functional deficiencies of the remaining acinar cells. Tissue engineering of human salivary gland organoids on microcarriers is a new approach for potential causative treatment of radiation-induced xerostomia. Before clinical application can be considered significant improvements in the in vitro cultivation of salivary gland tissue and scaffold design have to be realized.

Induction of Salivary Gland Epithelial Cell Injury in Sjogren's Syndrome: In Vitro Assessment of T Cell-derived Cytokines and Fas Protein Expression

Sjogren's syndrome (SS) is an exocrinopathy characterized by T cell infiltrates, salivary gland epithelial cell (SGEC) apoptosis and high Fas and FasL expression. To address the participation of T cell-derived cytokines and of Fas apoptotic pathway in SS glandular lesions, we utilized non-neoplastic SGEC lines established from SS patients and controls. Possibly attesting to their intrinsic activation, cell lines derived from SS patients displayed significantly higher constitutive Fas and FasL than controls. Surface co-expression of Fas and FasL was not associated with spontaneous fratricide apoptosis. SGEC were resistant to anti-Fas-mediated apoptosis (possibly owing to the constitutive expression of anti-apoptotic proteins cFLIP and Bcl-2), but became sensitive after protein or RNA synthesis inhibition. IFN-γ and TNF-α were able to upregulate surface Fas and FasL, whereas IL-1β downregulated surface FasL. IFN-γ (but not several other cytokines) reduced the survival of SGEC in a dose- and time-dependent manner and induced Fas/FasL-mediated apoptosis, directly and via anoikia. Dexamethasone inhibited the upregulation of Fas and FasL by IFN-γ and the induction of SGEC apoptosis and detachment by anti-Fas mAb or IFN-γ. Our findings indicate the injurious role of IFN-γ for the salivary epithelia of SS patients through the induction of Fas-mediated apoptosis and anoikia.

Cholangiocytes and primary biliary cirrhosis: prediction and predication

Although there have been descriptions of primary biliary cirrhosis (PBC) for more than 100 years, this condition first attracted the attention of immunologists in 1965, when patients’ sera were found to have antimitochondrial antibodies (AMAs) (1). The mitochondrial autoantigens, which are highly conserved among mitochondria and even chloroplasts (2) of divergent species, have been identified as the E2 components of the 2-oxo-acid dehydrogenase family — particularly the 74-kDa E2 subunit of the pyruvate dehydrogenase complex, which catalyzes the formation of acetyl CoA. The structurally and functionally related mitochondrial proteins BCOADC-E2 and OGDC-E2, as well as the E3 binding protein (3), are also found as autoantigens in PBC patients. Work with recombinant autoantigens has shown that the presence of AMAs is virtually diagnostic of PBC and that, while they may be detected in the sera of asymptomatic people years before the clinical diagnosis of PBC, they are very rarely found in non-PBC individuals (4, 5). The B cell epitope of PDC-E2 is found on the lipoyl domains, and antibody binding occurs when the antigen is complexed with lipoic acid (6). In fact, there are only five proteins in mammals that contain lipoic acid, and four of the five are autoantigens in PBC. Lipoic acid is bound to the lysine residue of the inner lipoyl domain, where it functions as a swinging arm to capture electrons during oxidative phosphorylation. Related work using cloned PDC-E2–specific T cell lines shows that the immunodominant T cell epitope also falls within the lipoyl domains. Interestingly, the frequency of PDC-E2–specific CD4+ T cell precursors is 100-fold higher in the liver than in PBMCs (7) in PBC patients, suggesting that these cells are recruited to the liver during the progression of the disease. However, the precise pathogenic role of these T cells is still under investigation. Despite the advances in the molecular characterization of immunoreactivity, a number of unexplained questions remain regarding the epidemiology and tissue specificity of this disease (3). Why is PBC overwhelmingly more common in women? Why is PBC not found in childhood? Why are granulomas found, and why is eosinophilia present in periductal inflammatory infiltrates? Why is PBC relatively more specific for small bile ducts than large bile ducts? Why should PBC recur following liver transplantation? Why is the incidence of PBC so much higher in families with an index case, even when there is no obvious MHC class I or class II association? What is the significance of the observation that some monoclonal antibodies to mitochondria appear to uniquely stain the bile duct cells in patients with PBC? Finally, why does the immune response induce damage to only a minor population of cells, those of the small ducts and ductules of the biliary and salivary epithelia?

High spontaneous CD40 expression by salivary gland epithelial cells in Sjogren's syndrome: possible evidence for intrinsic activation of epithelial cells

CD40 is a surface protein originally identified on B cells. Its interaction with CD40L on T cells plays an important role in the activation, proliferation and differentiation of B cells. During the recent years, CD40 has been identified in an expanding list of hemopoietic and nonhemopoietic cells and has received an increased interest based on its role in a variety of cell-mediated responses and its potential to participate in the pathogenesis of chronic inflammatory disorders. Sjogren's Syndrome (SS) is an autoimmune exocrinopathy, which is characterized by chronic lymphocytic infiltration of exocrine glands and aberrant activation of epithelial tissues. To investigate the participation of CD40 in the pathogenesis of SS, the expression of this protein was studied in cultured non-neoplastic salivary gland (SG) epithelial cell (SGEC) lines as well as in minor SG biopsies obtained from 17 SS patients and 12 controls. Immunocytochemical and flow cytometric analysis has revealed the occurrence of constitutively expressed CD40 molecules on the surface of our long-term cultured SGEC lines, which could be further induced by IFNγ and IL-1β, but not TNFα, IL-4, IL-6, GM-CSF and IFNγ. In SGEC lines derived from SS patients, the spontaneous expression of membranous CD40 was significantly higher compared to controls (P < 0,001), which is likely suggestive of their activated status. In SG biopsies, CD40 was constitutively expressed by B cells, ductal epithelial cells and endothelial cells but not by other glandular cell types, such as acinar cells, myoepithelial cells and fibroblasts. In addition, CD40L staining was also detected in 30-50% of the infiltrating T cells in the biopsies of SS patients. Our results possibly reveal the immunoregulatory potential of SGEC and lend further support to a model of intrinsic activation in salivary epithelia in SS, whereby these cells actively participate in the induction and maintenance of lymphocytic infiltrates of patients.

EGF-dependent lobule formation and FGF7-dependent stalk elongation in branching morphogenesis of mouse salivary epithelium in vitro.

When supplemented with appropriate growth factors, salivary gland epithelial explants isolated from mouse embryos undergo branching morphogenesis in vitro in the absence of mesenchyme. Epidermal growth factor (EGF) induces lobule formation, while fibroblast growth factor 7 (FGF7) promotes stalk elongation. A mixture of EGF and FGF7 produces an intermediate morphology, which resembles the branching pattern of salivary epithelium observed in vivo. To investigate how lobule formation and stalk elongation are related to the pattern of epithelial cell proliferation induced by EGF and FGF7, we performed a bromodeoxyuridine labeling study in whole-mount preparations. During the initial steps of lobule formation in EGF cultures, cleft and non-cleft regions had similar proliferative activity. However, once clefts had fully deepened, cells with low proliferative activity appeared at the bottom of the clefts. In contrast, during stalk elongation in FGF7 cultures, distal regions of the explants always showed higher proliferative activity than proximal regions. These results suggest that stalk elongation, but not cleft formation, may result from differential cell proliferation.

EGF‐dependent lobule formation and FGF7‐dependent stalk elongation in branching morphogenesis of mouse salivary epithelium in vitro

EGF‐dependent lobule formation and FGF7‐dependent stalk elongation in branching morphogenesis of mouse salivary epithelium in vitro

Significant role of laminin-1 in branching morphogenesis of mouse salivary epithelium cultured in basement membrane matrix.

Mouse submandibular epithelium shows branching morphogenesis in mesenchyme-free conditions when covered with a basement membrane matrix (Matrigel) in medium supplemented with epidermal growth factor. In the present study, the role of laminin-1 (LN1), a major glycoprotein of Matrigel, in this culture system was defined. When the epithelium was cultured in a LN1-nidogen gel, the epithelium showed much branching, comparable to that observed with Matrigel. By electron microscopy, only a felt-like matrix was formed on the epithelial surface in the LN1-nidogen gel cultures, while an organized basal lamina structure was formed on the epithelial surface in direct or transfilter recombination cultures with mesenchyme. Next, the epithelium covered with Matrigel was cultured in medium containing either biologically active peptides from LN1, IKVAV-including peptide (2097-2108), AG10 (2183-2194), AG32 (2370-2381) or AG73 (2719-2730) from the alpha1 chain, or YIGSR-including peptide (926-933) from the beta1 chain. Only AG73 (RKRLQVQLSIRT from the alpha1 chain carboxyl-terminal globular domain) inhibited the epithelial branching in Matrigel. These results suggest that LN1-nidogen can support the branching morphogenesis of submandibular epithelium even if LN1-nidogen is not assembled into an intact basal lamina, and that the AG73 sequence is an important site on LN1, which interacts with submandibular epithelial cells.

Transepithelial fluid shift generated by osmolarity gradients in unstimulated perfused rat submandibular glands.

The effects of osmotic gradients on transepithelial water movements were examined in unstimulated perfused submandibular glands of the rat. Osmotic gradients were applied transepithelially by adding sucrose to or removing it from the perfusate. An infusion of hypotonic perfusate shifted fluid from the interstitium to the lumen (luminal fluid shift) transiently, whereas an infusion of hypertonic perfusate shifted fluid from the lumen to the interstitium (interstitial fluid shift) transiently. The amount of fluid shifted from lumen to interstitium increased as the luminal fluid osmolarity was raised or as the perfusate osmolarity was reduced. Thus, fluid movements across the salivary epithelium were shown to be simply dependent on the osmolarity difference between lumen and interstitium. To estimate the effective pore radius of the epithelium, non-electrolyte solutions (urea, dimethylurea, diethylurea, mannitol, sucrose and maltotriose) were also used as luminal solutions. The results from non-electrolyte experiments showed that the effective pore radius of the passage for non-electrolytes was slightly larger than 0.38 nm. Solutes smaller than mannitol were less effective in opposing the interstitial fluid shift, and the value of effective pore radius in this report was similar to that of the secretory water pathway that has been measured in solvent drag studies (0.4 0.45 nm). These findings suggest that the passage for non-electrolytes may be water transport pathway in salivary epithelium.

Undifferentiated carcinoma of the parotid gland in a white patient: Detection of Epstein-Barr virus by in situ hybridization

Paraffin sections of an undifferentiated salivary gland carcinoma of lymphoepithelioma type, arising in a white (Greek) patient and confirmed by immunohistochemistry, were examined for the presence of Epstein-Barr virus (EBV), using in situ hybridization to detect EBV-specific EBER1 message. Epstein-Barr virus was detected in malignant epithelial cells, but was not found in lymphoid stroma or in residual benign salivary epithelium. These results confirm the existence of an association between EBV and tumor cells of undifferentiated carcinoma of parotid gland. This is the first demonstration of EBV in a salivary gland lymphoepithelioma arising in a non-Eskimo, white patient. This finding suggests that the association of EBV with undifferentiated salivary gland carcinoma may exist in geographic regions remote from Greenland.