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The article presents background information on reports published within the issue, which are summaries of conference papers presented at the 13th International Conference on Oral Biology, held in Victoria, British Columbia, Canada, from March 14 through 16, 1994.

To study the relationship between glucose metabolic status and salivary gland function in different-aged persons, subjects with diabetes mellitus (DM = 11), impaired glucose tolerance (IGT = 26), and controls (n = 26), aged 24 to 93, were examined in the oral physiology component of the baltimore Longitudinal Study of Aging. All were generally healthy (except DM) and nonmedicated. The controls and subjects with IGT were classified using World Health Organization criteria, and diabetic status was assessed using HblAc levels. Unstimulated and 2% citrate-stimulated parotid and submandibular salivary flow rates were collected, and subjective responses to questions about salivary hypofunction were evaluated. No statistically significant differences were observed between the three groups, nor between young and old subjects with altered glucose metabolism. These findings suggest that among well-controlled individuals with altered glucose metabolism, salivary gland function is not significantly impaired [ABSTRACT FROM PUBLISHER]

Perception of oral sensory intensity was assessed in healthy, community-dwelling men (n = 46) and women (n = 41) between 25 and 93 years of age. Cross-modal matches of distance to perceived intensity were obtained for five types of oral stimuli (sugar water, salt water, heated or chilled water, water thickened with methylcellulose, and local pressure on the dorsal tongue). Differences among stimulus types were observed for measures of response size (mean, median, maximum, and range of response distance and rate of increase with stimulus strength), but not measures of judgment quality, repeatability (ICC), and conformity to a linear rise with stimulus strength (r). Age had no significant effect on any of the response measures for any stimulus type except pressure. All measures of response to lingual pressure except median size declined significantly with age. We conclude that (a) the various oral stimulus types elicit perceptions that differ in intensity but were judged with similar accuracy, and that (b) aging brings a specific decline in the perception of localized lingual pressure while both size and accuracy of intensity judgments are maintained for the other oral sensitivities tested [ABSTRACT FROM PUBLISHER]

Dementia of the alzheimer type (DAT) is the most common type of dementia among the elderly. Alzheimer's disease is a major public health problem, yet little is known about the potential oral consequences of the disease. Because saliva is believed to be essential for the preservation of oral health and function, salivary gland fluid output was evaluated in a population of essentially healthy patients with early-stage DAT. Unstimulated and stimulated parotid and submandibular salivary gland secretions were collected from 28 nonmedicated and otherwise healthy DAT patients, and 35 age-matched healthy controls. Submandibular saliva flow rates were significantly lower among the patients with DAT compared to controls, while parotid flow rates did not differ. The results suggest a selective impairment in submandibular gland function in essentially healthy patients with early-stage DAT [ABSTRACT FROM PUBLISHER]

The most significant long-term complication of radiotherapy in the head-and-neck region is hyposalivation and its related complaints, particularily xerostomia. This review addresses the pathophysiology underlying irradiation damage to salivary gland tissue, the consequences of radiation injury, and issues contributing to the clinical management of salivary gland hypofunction and xerostomia. These include ways to (1) prevent or minimize radiation injury of salivary gland tissue, (2) manage radiation-induced hyposalivation and xerostomia, and (3) restore the function of salivary gland tissue damaged by radiotherapy. [ABSTRACT FROM AUTHOR]

Classically, the 5′ and 3′ long terminal repeats (LTRs) are considered necessary but not sufficient for retroviral integration. Recently, we reported that inclusion of these and additional elements from Moloney murine leukemia virus (MoMLV) facilitated transgene integration, without retroviral integrase, when placed in an adenoviral context (AdLTR-luc vector) (Nat. Biotech. 18 (2000), 176; Biochem. Biophys. Res. Commun. 300 (2003), 115). To help understand this nonhomologous DNA recombination event, we constructed another vector, AdELP-luc, with 2.7 kb of MoMLV elements identically placed into an E1-deleted adenovirus type 5 backbone upstream of a luciferase cDNA reporter gene. Unlike AdLTR-luc, no MoMLV elements were placed downstream of the expression cassette. AdELP-luc readily infected epithelial cells in vitro. Southern hybridizations with DNA from cloned cells showed that disruption of the MoMLV sequences occurred. One cell clone, grown in vitro without any special selection medium for 9 months, exhibited stable vector integration and luciferase activity. Importantly, both Southern hybridization and FISH analyses showed that in addition to the MoMLV elements and expression cassette, substantial adenoviral sequence downstream of the luciferase cDNA was genomically integrated. These results suggest that the 2.7 kb of MoMLV sequence included in AdELP-luc have cis-acting functions and mediates an unusual integration event. [Copyright &y& Elsevier]

The frequency with which the hybrid vector AdLTR-luc mediates genomic integration [Nat. Biotech. 18 (2000) 176–180] is unknown. To address this, we constructed AdLTR-red, using the AdLTR-luc backbone and the enhanced red fluorescence protein cDNA. Kinetic studies showed that AdLTR-red and a conventional adenoviral vector, AdCMV-red, entered and transduced epithelial cells comparably. AdLTR-red integration frequency in vitro, i.e., the percentage of red clones after 10–12 doubling times from limiting dilutions, was 8.0% (36/450; at 67 particles/cell). With AdCMV-red, 0/549 clones were integration-positive. Seven days after AdLTR-luc or AdCMV-luc (1011 particles) femoral vein administration to adult rats splenocytes were prepared, stimulated with concanavalin A, and examined by FISH. AdLTR-luc integration occurred in 5–11% of mitotic rat splenocytes, while no unequivocal integration was found with AdCMV-luc. These data provide the first quantitative evidence of the frequency for genomic integration with this hybrid vector. [Copyright &y& Elsevier]

Saliva is essential for the preservation of oral-pharyngeal health, and disorders of salivary physiology are associated with numerous oral and pharyngeal problems, particularly in older people. Although salivary function is remarkably intact in healthy aging, medical problems, medications, and head and neck radiotherapy can cause salivary dysfunction and complaints of xerostomia among older people. Sjögren's syndrome, an autoimmune exocrinopathy, is the most common medical disease associated with salivary dysfunction. Medications with anticholinergic side effects will impair salivary output, and head and neck radiotherapy for cancer will cause permanent destruction of salivary glands. Treatments for salivary problems are based upon establishing a diagnosis, protecting oral and pharyngeal health, stimulating remaining glands, and replacing lost salivary fluids. [ABSTRACT FROM AUTHOR]

Head and neck cancer patients treated by radiation commonly suffer from a devastating side effect known as dry-mouth syndrome, which results from the irreversible loss of salivary gland function via mechanisms that are not completely understood. In this study, we used a mouse model of radiationinduced salivary hypofunction to investigate the outcomes of DNA damage in the head and neck region.We demonstrate that the loss of salivary function was closely accompanied by cellular senescence, as evidenced by a persistent DNA damage response (γH2AX and 53BP1) and the expression of senescence-associated markers (SA-βgal, p19ARF, and DcR2) and secretory phenotype (SASP) factors (PAI-1 and IL6). Notably, profound apoptosis or necrosis was not observed in irradiated regions. Signs of cellular senescence were also apparent in irradiated salivary glands surgically resected from human patients who underwent radiotherapy. Importantly, using IL6 knockout mice, we found that sustained expression of IL6 in the salivary gland long after initiation of radiation-induced DNA damage was required for both senescence and hypofunction. Additionally, we demonstrate that IL6 pretreatment prevented both senescence and salivary gland hypofunction via a mechanism involving enhanced DNA damage repair. Collectively, these results indicate that cellular senescence is a fundamental mechanism driving radiation-induced damage in the salivary gland and suggest that IL6 pretreatment may represent a promising therapeutic strategy to preserve salivary gland function in head and neck cancer patients undergoing radiotherapy. [ABSTRACT FROM AUTHOR]

Adenovirus (Ad) mediated expression of therapeutic proteins from salivary glands can result in the delivery of biologically active proteins into the circulation where they impart their physiological function. In recent years, Ad vector delivery to salivary glands (SGs) has emerged as a viable option for gene therapy. Here, we engineered a variant of human proinsulin (hProinsulin-B10) into an Ad vector and demonstrated its ability to transduce cell lines, and express a bioactive protein that induces the phosphorylation of AKT, a key insulin signaling molecule. We also examined its expression in mice following delivery of the vector to the parotid gland (PTG), the submandibular gland (SMG) or to the liver via the tail vein and assessed transgenic protein expression and vector containment for each delivery method. In all cases, hProinsulin-B10 was expressed and secreted into the circulation. Lower levels of circulating hProinsulin-B10 were obtained from the PTG while higher levels were obtained from the tail vein and the SMG; however, vector particle containment was best when delivered to the SMG. Expression of hProinsulin-B10 in the SMG of chemically induced diabetic mice prevented excessive hyperglycemia observed in untreated mice. These results demonstrate that hProinsulin-B10 can be expressed and secreted into the circulation from SGs and can function physiologically in vivo. The ability to remediate a diabetic phenotype in a model of type 1 diabetes mellitus is the first step in an effort that may lead to a possible therapy for diabetes. [ABSTRACT FROM AUTHOR]

Peptide hormones and their cognate receptors belonging to neuropeptide Y (NPY) family mediate diverse biological functions in a number of tissues. Recently, we discovered the presence of the gut satiation peptide YY (PYY) in saliva of mice and humans and defined its role in the regulation of food intake and body weight maintenance. Here we report the systematic analysis of expression patterns of all NPY receptors (Rs), Y1R, Y2R, Y4R, and Y5R in lingual epithelia in mice. Using four independent assays, immunohistochemistry, in situ hybridization, immunocytochemistry and RT PCR, we show that the morphologically different layers of the keratinized stratified epithelium of the dorsal layer of the tongue express Y receptors in a very distinctive yet overlapping pattern. In particular, the monolayer of basal progenitor cells expresses both Y1 and Y2 receptors. Y1Rs are present in the parabasal prickle cell layer and the granular layer, while differentiated keratinocytes display abundant Y5Rs. Y4Rs are expressed substantially in the neuronal fibers innervating the lamina propria and mechanoreceptors. Basal epithelial cells positive for Y2Rs respond robustly to PYY3-36 by increasing intracellular Ca2+ suggesting their possible functional interaction with salivary PYY. In taste buds of the circumvallate papillae, some taste receptor cells (TRCs) express YRs localized primarily at the apical domain, indicative of their potential role in taste perception. Some of the YR-positive TRCs are co-localized with neuronal cell adhesion molecule (NCAM), suggesting that these TRCs may have synaptic contacts with nerve terminals. In summary, we show that all YRs are abundantly expressed in multiple lingual cell types, including epithelial progenitors, keratinocytes, neuronal dendrites and TRCs. These results suggest that these receptors may be involved in the mediation of a wide variety of functions, including proliferation, differentiation, motility, taste perception and satiation. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate if two pharmacological agents, Tempol and D-methionine (D-met), are able to prevent oral mucositis in mice after exposure to ionizing radiation ± cisplatin.Methods and Materials: Female C3H mice, ∼8 weeks old, were irradiated with five fractionated doses ± cisplatin to induce oral mucositis (lingual ulcers). Just before irradiation and chemotherapy, mice were treated, either alone or in combination, with different doses of Tempol (by intraperitoneal [ip] injection or topically, as an oral gel) and D-met (by gavage). Thereafter, mice were sacrificed and tongues were harvested and stained with a solution of Toluidine Blue. Ulcer size and tongue epithelial thickness were measured.Results: Significant lingual ulcers resulted from 5 × 8 Gy radiation fractions, which were enhanced with cisplatin treatment. D-met provided stereospecific partial protection from lingual ulceration after radiation. Tempol, via both routes of administration, provided nearly complete protection from lingual ulceration. D-met plus a suboptimal ip dose of Tempol also provided complete protection.Conclusions: Two fairly simple pharmacological treatments were able to markedly reduce chemoradiation-induced oral mucositis in mice. This proof of concept study suggests that Tempol, alone or in combination with D-met, may be a useful and convenient way to prevent the severe oral mucositis that results from head-and-neck cancer therapy. [ABSTRACT FROM AUTHOR]

Peptide YY3-36 is a satiation hormone released postprandially into the bloodstream from L-endocrine cells in the gut epithelia. In the current report, we demonstrate PYY3-36 is also present in murine as well as in human saliva. In mice, salivary PYY3-36 derives from plasma and is also synthesized in the taste cells in taste buds of the tongue. Moreover, the cognate receptor Y2R is abundantly expressed in the basal layer of the progenitor cells of the tongue epithelia and von Ebner's gland. The acute augmentation of salivary PYY3-36 induced stronger satiation as demonstrated in feeding behavioral studies. The effect is mediated through the activation of the specific Y2 receptor expressed in the lingual epithelial cells. In a longterm study involving diet-induced obese (DIO) mice, a sustained increase in PYY3-36 was achieved using viral vectormediated gene delivery targeting salivary glands. The chronic increase in salivary PYY3-36 resulted in a significant long-term reduction in food intake (FI) and body weight (BW). Thus this study provides evidence for new functions of the previously characterized gut peptide PYY3-36 suggesting a potential simple and efficient alternative therapeutic approach for the treatment of obesity. [ABSTRACT FROM AUTHOR]

Clinical gene transfer holds promise for the treatment of many inherited and acquired disorders. A key consideration for all clinical gene transfer applications is the tight control of transgene expression. We have examined the safety and biodistribution of a serotype 2, recombinant adeno-associated viral (AAV2) vector that encodes a rapamycin-responsive chimeric transcription factor, which regulates the expression of a therapeutic transgene (human erythropoietin [hEpo]). The vector, AAV2-TF2.3w-hEpo (2.5 × 107–2.5 × 1010 particles), was administered once to a single submandibular gland of male and female mice and mediated hEpo expression in vivo following a rapamycin injection but not in its absence. Control (saline treated) and vector-treated animals maintained their weight, and consumed food and water, similarly. Vector delivery led to no significant toxicological effects as judged by hematology, clinical chemistry, and gross and microscopic pathology evaluations. On day 3 after vector delivery, vector copies were not only abundant in the targeted right submandibular gland but also detected in multiple other tissues. Vector was cleared from the targeted gland much more rapidly in female mice than in male mice. Overall, our results are consistent with the notion that administration of the AAV2-TF2.3w-hEpo vector to salivary glands posed no significant risk in mice. [ABSTRACT FROM AUTHOR]

Blood- and marrow-derived stem cells (BMDSCs) provide disease-ameliorating effects for cardiovascular and autoimmune diseases. Microchimerism from donor BMDSCs has been reported in several recipient tissues. We hypothesized that this finding suggests a potential use of BMDSCs in the treatment of salivary dysfunctions. We investigated the presence of Y chromosome-positive cells in salivary gland biopsies of 5 females who had received a marrow or blood stem cell transplant from male donors. One to 16 years after transplantation, all recipients exhibited scattered Y chromosome-positive cells in the acini, ducts, and stroma of their salivary glands (mean of 1.01%). Potentially, these cells can be markers of transplantation tolerance, contribute to neoplastic epithelial tissues, or engraft at sites of injury. In addition, transplantation of BMDSCs could be used for treatment of Sjögren’s syndrome and salivary glands damaged by therapeutic irradiation for cancers of the head and neck. [Copyright &y& Elsevier]

Purpose: To evaluate the effect of irradiation on microvascular endothelial cells in miniature pig parotid glands. Methods and Materials: A single 25-Gy dose of irradiation (IR) was delivered to parotid glands of 6 miniature pigs. Three other animals served as non-IR controls. Local blood flow rate in glands was measured pre- and post-IR with an ultrasonic Doppler analyzer. Samples of parotid gland tissue were taken at 4 h, 24 h, 1 week, and 2 weeks after IR for microvascular density (MVD) analysis and sphingomyelinase (SMase) assay. Histopathology and immunohistochemical staining (anti-CD31 and anti-AQP1) were used to assess morphological changes. MVD was determined by calculating the number of CD31- or AQP1-stained cells per field. A terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay was used to detect apoptotic cells. The activity of acid and neutral Mg2+-dependent SMase (ASMase and NSMase, respectively) was also assayed. Results: Local parotid gland blood flow rate decreased rapidly at 4 h post-IR and remained below control levels throughout the 14-day observation period. Parotid MVD also declined from 4 to 24 hours and remained below control levels thereafter. The activity levels of ASMase and NSMase in parotid glands increased rapidly from 4 to 24 h post-IR and then declined gradually. The frequency of detecting apoptotic nuclei in the glands followed similar kinetics. Conclusions: Single-dose IR led to a significant reduction of MVD and local blood flow rate, indicating marked damage to microvascular endothelial cells in miniature pig parotid glands. The significant and rapid increases of ASMase and NSMase activity levels may be important in this IR-induced damage. [ABSTRACT FROM AUTHOR]

Abstract: Salivary glands are classical exocrine glands whose external secretions result in the production of saliva. However, in addition to the secretion of exocrine proteins, salivary epithelial cells are also capable of secreting proteins internally, into the bloodstream. This brief review examines the potential for using salivary epithelial cells as a target site for in situ gene transfer, with an ultimate goal of producing therapeutic proteins for treating both systemic and upper gastrointestinal tract disorders. The review discusses the protein secretory pathways reported to be present in salivary epithelial cells, the viral gene transfer vectors shown useful for transducing these cells, model transgenic secretory proteins examined, and some clinical conditions that might benefit from such salivary gland gene transfer. [Copyright &y& Elsevier]

Abstract: Polarized salivary epithelial cells can sort secretory proteins towards either the basolateral or apical pole. Transgenic human parathyroid hormone (hPTH) exclusively sorts apically in rat submandibular glands. To help understand this specific process we modified the hPTH cDNA sequence and delivered the cDNAs to glands in vivo using adenoviral (Ad) vectors. The Ad vectors encoded: (1) the native form of hPTH (Ad.pre-pro-hPTH1–84), (2) the native sequence, but with the pro-segment deleted (Ad.pre-hPTH1–84), and (3) a sequence containing the pre-segment followed by the first 34 amino acids of hPTH (Ad.pre-hPTH1–34). hPTH production and sorting were studied after two days. All constructs were effectively transcribed in targeted glands. However, the pre-hPTH1–84 modification led to reduced hPTH secretion and production, while no immunoreactive hPTH resulted from pre-hPTH1–34 cDNA infusion. The pre-hPTH1–84 modification had no effect on apical sorting. These in vivo results show that the signal responsible for hPTH’s apical sorting does not reside in the pro-segment and that deleting both the pro-segment and the carboxyl-terminal region severely impairs post-translational processing of hPTH. [Copyright &y& Elsevier]

An abstract of the article "The Effects of Transgene and Cassette Size on Recombinant AAV2 Production and Expression.," by Corinne M. Goldsmith, Antonis Voutetakis and Bruce J. Baum is presented.

Abstract: Neuroendocrine and exocrine cells secrete proteins in either a constitutive manner or via the regulated secretory pathway (RSP), but the specific sorting mechanisms involved are not fully understood. After gene transfer to rat salivary glands, the transgenic model proteins human growth hormone (hGH) and erythropoietin (hEpo) are secreted primarily into saliva (RSP; exocrine) and serum (constitutive; endocrine), respectively. We hypothesized that fusion of hGH at either the C-terminus or the N-terminus of hEpo would re-direct hEpo from the bloodstream into saliva. We constructed and expressed two fusion proteins, hEpo-hGH and hGH-hEpo, using serotype 5-adenoviral vectors, and delivered them to rat submandibular glands in vivo via retroductal cannulation. Both the hEpo-hGH and hGH-hEpo fusion proteins, but not hEpo alone, were secreted primarily into saliva (p <0.0001 and p =0.0083, respectively). These in vivo studies demonstrate for the first time that hGH, in an N- as well as C-terminal position, influences the secretion of a constitutive pathway protein. [Copyright &y& Elsevier]

We studied the effects of specific retroviral elements in a first-generation serotype 5 adenoviral (Ad5) vector, AdLTR2EF1α-hEPO. This vector contains 858 base pair (bp) [251-bp envelope sequence plus 607-bp long-terminal repeat (LTR)] from Moloney murine leukemia virus (MoMLV), upstream of the human elongation factor-1α (EF1α) promoter and human erythropoietin (hEPO) cDNA, with the LTR sequence downstream of the polyadenylation signal. We compared expression of AdLTR2EF1α-hEPO with corresponding expressions of two conventional Ad5 vectors, AdEF1α-hEPO and AdCMV-hEPO, in vivo in submandibular glands in rats. Both the conventional vectors yielded low serum hEPO levels by day 7, and little change in hematocrits. In contrast, after receiving AdLTR2EF1α-hEPO, the rats showed elevated hEPO levels and hematocrits for 1–3 months. In vitro studies showed that the integration efficiencies of all the vectors were similar (∼10−3). Approximately 0.1% of the vector genomes were present 1 year after delivery in the case of each of the three vectors, primarily as intact linear double-strand DNA. The unique results seen with AdLTR2EF1α-hEPO are partly because of LTR enhancer activity. However, other cis-acting activity, which is not immunomodulatory but nevertheless influences promoter methylation, appears to be involved. A vector such as AdLTR2EF1α-hEPO may prove useful in clinical applications in which extended, but not “permanent,” transgene expression is desirable.Molecular Therapy (2008) 16 6, 1089–1097 doi:10.1038/mt.2008.56 [ABSTRACT FROM AUTHOR]

Treatment of most head and neck cancers includes radiotherapy. Salivary glands (SGs) in the irradiation (IR) field are irreversibly damaged resulting in severe hyposalivation. We evaluated the importance of SG endothelial cells to this IR-induced injury, and whether serotype 5 adenoviral (Ad5) vector-mediated transfer of basic fibroblast growth factor (AdbFGF) or vascular endothelial growth factor (AdVEGF) complementary DNAs would afford radioprotection. Four hours after IR, microvessel density (MVD) in SGs decreased by ∼45%. However, if mice were pre-treated with either AdVEGF or AdbFGF 48 hours before IR the loss in MVD was significantly reduced. An irrelevant vector, AdLacZ, encoding Escherichia coli β-galactosidase, was without effect. After 8 weeks, IR reduced salivary flow by ∼65% in untreated mice. Mice pre-treated (using 5 × 109 particles/gland 48 hours prior to IR) with AdLacZ exhibited a reduction in salivary flow similar to untreated mice receiving IR. However, irradiated mice pre-treated with AdbFGF or AdVEGF showed a significant improvement in their salivary flow, to ∼70% (P < 0.01) and 80% (P < 0.01), respectively, compared to non-irradiated control mice. These results are consistent with the notion that injury to the adjacent microvasculature may play an important role in SG radiation damage. Furthermore, our results suggest that a local transient treatment directed at protecting SG endothelial cells may be beneficial for patients undergoing IR for head and neck cancer.Molecular Therapy (2007) 15 12, 2101–2106. doi:10.1038/sj.mt.6300296 [ABSTRACT FROM AUTHOR]

The article focuses on a study aimed to delineate the precise function of transforming growth factor β (TGFβ) signaling in salivary gland inflammation. The TGFβ signaling in mouse salivary glands was impaired by conditionally inactivating expression of TGFβ receptor type I. The results suggested that female mice are uniquely more susceptible to developing inflammatory disorders due to impaired TGFβ signaling in their salivary glands.

Purpose: To evaluate the effects of a solitary megadose protocol of ionizing radiation (IR) on the structure and function of the miniature pig (minipig) parotid gland. Methods and Materials: Fourteen minipigs were subjected to either 15 or 20 Gy to one parotid gland with a linear accelerator, whereas another four minipigs served as non-IR controls. Salivary flow rates and salivary chemistries were measured pre-IR and 4 and 16 weeks post-IR. A quantitative assessment of gland weight and acinar area and detailed serum chemistry and hematologic analyses were also performed. Results: Parotid flow rates decreased by approximately 50% either with 20 Gy at 4 weeks, or 15 Gy at 16 weeks post-IR. In the 20 Gy group, salivary flow rates were reduced by approximately 80% at 16 weeks post-IR. A significant decrease in salivary calcium and amylase and an increase of salivary potassium levels were found in both IR groups. There were also transient alterations in serum chemistry and hematology parameters post-IR. Parotid gland weights were significantly decreased (−50%) in the 15 and 20 Gy groups at 4 and 16 weeks post-IR. Additionally, the acinar cell area in glands of both IR groups was significantly reduced from that in control glands at both the 4 and 16 weeks time points. Conclusion: Structural changes in salivary gland parenchyma occurred relatively early after IR, whereas the alterations in salivary output were relatively delayed. Further, reductions in salivary flow were not proportional to acinar cell area loss. Together, these findings suggest that nonparenchymal IR damage likely contributes to IR-induced salivary hypofunction. [Copyright &y& Elsevier]

Abstract: AQP5 and AQP8 possess targeting/retention motifs which mediate their localization to the apical and basolateral membranes, respectively, of polarized MDCK-II cells. As targeting/retention motifs have been localized to the N- or C-termini of other AQPs, we sought the location of such motifs in AQPs 5 and 8 by exchanging their corresponding N- or C-termini and examining the expression, localization, and function of the resultant chimeras. We did not detect the expression of constructs in which the C-terminus of AQP5 was replaced by the C-terminus of AQP8. Substitution of the N-terminus of AQP8 for the N-terminus of AQP5 generated a construct which was trapped intracellularly and did not significantly facilitate transepithelial fluid movement. In contrast, modifications of the N- and C-termini of AQP8 were better tolerated. Substitution of either AQP8 terminus by the corresponding AQP5 terminus generated constructs which localized to basolateral membranes and facilitated transepithelial fluid movement. Our results suggest that, unlike the other AQP targeting/retention signals reported thus far, an AQP8 basolateral targeting/retention motif might reside between the two cytosolic termini. [Copyright &y& Elsevier]

The use of critical-for-life organs (e.g., liver or lung) for systemic gene therapeutics can lead to serious safety concerns. To circumvent such issues, we have considered salivary glands (SGs) as an alternative gene therapeutics target tissue. Given the high secretory abilities of SGs, we hypothesized that administration of low doses of recombinant adeno-associated virus (AAV) vectors would allow for therapeutic levels of transgene-encoded secretory proteins in the bloodstream. We administered 109 particles of an AAV vector encoding human erythropoietin (hEPO) directly to individual mouse submandibular SGs. Serum hEPO reached maximum levels 8-12 weeks after gene delivery and remained relatively stable for 54 weeks (longest time studied). Hematocrit levels were similarly increased. Moreover, these effects proved to be vector dose-dependent, and even a dosage as low as 108 particles per animal led to significant increases in hEPO and hematocrit levels. Vector DNA was detected only within the targeted SGs, and levels of AAV copies within SGs were highly correlated with serum hEPO levels (r = 0.98). These results show that SGs appear to be promising targets with potential clinical applicability for systemic gene therapeutics. [ABSTRACT FROM AUTHOR]

Background: We examined the distribution and toxicity associated with a single salivary gland administration of a recombinant adenoviral vector, AdCMVH3, encoding human histatin 3.Methods: Adult rats received different doses of AdCMVH3 (0, 106, 3 x 107, and 109 pfu; 50 microl) via the right submandibular gland and were followed for 15 days. Food consumption, weight gain, clinical appearance, and serum chemistry were monitored, and a necropsy was performed. Vector distribution was examined by polymerase chain reaction, and selected saliva samples were tested for replication-competent adenovirus (RCA).Results: All animals survived to sacrifice (days 2, 8, and 15), and appeared normal clinically. There were no differences in food consumption, weight gain, and serum chemistry. The only consistent necropsy findings were lymphoid infiltrates and necrosis in the target submandibular glands of high-dosage animals. AdCMVH3 detection was virus dose dependent, decreased with time, and at low dose preferentially observed in the targeted gland. No RCA was detected.Conclusions: Salivary gland administration of 109 pfu AdCMVH3 elicits an initial focal pathologic response and wide tissue distribution. There is no associated systemic toxicity up to 15 days, and lower doses are primarily found in glands. [ABSTRACT FROM AUTHOR]

Summary: Background: Adult bone marrow-derived (BMD) cells could be used to repair damaged organs and tissues, but the intrinsic plasticity of these cells has been questioned by results of in-vitro studies suggesting that such cells might fuse with other cells giving the appearance of differentiation. We aimed to determine whether fusion events are important in vivo. Methods: To test whether BMD cells can colonise an epithelial tissue and differentiate there without fusion, we did in-situ hybridisation with Y and X chromosome probes labelled with 35-sulphur or digoxigenin, or labelled fluorescently. We did immunohistochemistry with anticytokeratin 13 along with fluorescence in-situ hybridisation to identify Y-chromosome positive buccal epithelial cells in cheek scrapings obtained from five females who had received either a bone-marrow transplant or an allogeneic mobilised peripheral-blood progenitor-cell transplant (enriched in CD34+ cells) from male donors. Findings: When examined 4-6 years after male-to-female marrow-cell transplantation, all female recipients had Y-chromosome-positive buccal cells (0.8-12.7%). In more than 9700 cells studied, we detected only one XXXY-positive cell (0.01%) and one XXY cell (0.01%), both of which could have arisen when an XY cell fused with an XX cell. Interpretation: Male BMD cells migrate into the cheek and differentiate into epithelial cells, an occurrence that does not depend on fusion of BMD cells to recipient cells. This finding might be an example of transdifferentiation of haemopoietic or stromal progenitor cells. Plasticity of BMD cells could be useful in regenerative medicine. [ABSTRACT FROM AUTHOR]

Transfer of the human aquaporin 1 (hAQP1) gene provides a novel way to potentially correct the severe salivary hypofunction associated with therapeutic radiation for head and neck cancer. To facilitate the study of individual cells transduced with this gene, we have designed a fusion product of the hAQP1 and jellyfish green fluorescent protein (GFP) cDNAs. An expression plasmid, pACCMVhAQP1GFP, and a recombinant adenovirus, AdhAQP1GFP, encoding this fusion product were constructed. Both the recombinant plasmid and virus directed the expression of the encoded, 55-kDa fusion protein (hAQP1GFP), which was detected in the plasma membranes of several epithelial cell lines (293, SMIE, and A5). hAQP1GFP was functionally active and facilitated fluid movement across a polarized salivary epithelial cell monolayer (∼5-fold noninfected controls) in response to an osmotic gradient. In response to a hypotonic challenge, individual epithelial cells expressing the fusion protein exhibited significantly more capacitance (used herein as an indicator of cell swelling) than control cells. Conversely, in response to a hypertonic challenge, individual infected cells shrunk more rapidly (∼2- to 3-fold) and to a greater extent than control cells. We conclude that AdhAQP1GFP is a useful experimental tool to identify and study individual cells expressing a water channel transgene. [ABSTRACT FROM AUTHOR]

This study evaluated the safety and efficacy of a single administration of a recombinant adenovirus encoding human aquaporin-1 (AdhAQP1) to the parotid glands of adult rhesus monkeys. In anticipation of possible clinical use of this virus to correct irradiation damage to salivary glands, AdhAQP1 was administered (at either 2 × 109 or 1 × 108 plaque-forming units/gland) intraductally to irradiated glands and to their contralateral nonirradiated glands. Radiation (single dose, 10 Gy) significantly reduced salivary flow in exposed glands. Virus administration resulted in gene transfer to irradiated and nonirradiated glands and was without untoward local (salivary) or systemic (sera chemistry, complete blood count) effects in all animals. However, the effect of AdhAQP1 administration varied and did not result in a consistent positive effect on salivary flow rates for all animals under these experimental conditions. We conclude that a single adenoviral-mediated gene transfer to primate salivary glands is well-tolerated, although its functional utility in enhancing fluid secretion from irradiated parotid glands is inconsistent. [ABSTRACT FROM AUTHOR]

Describes the construction of a replication-deficient, recombinant adenovirus encoding human aquaporin-1 (hAQP1). Direction of hAQP1 expression in epithelial cell lines in vitro; Localization in the apical and basolateral plasma membranes; Fluid movement across monolayers infected by AdhAQP1.

An epithelial cell line, RSMT[SUBx], has been established from the submandibular gland of weanling Fisher 344 rats by treatment of explanted tissue clumps with 3-methylocholanthrene. These cells exhibit a polygonal shape on light microscopy and a polar appearance, with desmosomes, terminal bar-like structures, surface microvilli and cytoplasmic interdigitations, when examined by electron microscopy. The cells react positively with an antiserum to cytoskeletal keratin, and a commercial monoclonal antibody to an "epithelial membrane antigen," An antiserum, prepared against early passage cells in hamsters, reacts primarily with ductal elements in tissue sections of submandibular gland, as does an antiserum prepared in mice with late passage cells. The cells are easily passaged and have been maintained for more than two years in continuous culture. [ABSTRACT FROM AUTHOR]

We have examined the safety of a replication-deficient recombinant adenovirus administered at a single, high dose intraductally to rat submandibular glands or systemically via the femoral vein. The virus used directed the synthesis of human aquaporin-1, a water channel protein, and is termed AdhAQP1. Comparisons were made 1 and 9 days post-infection with animals administered either a similar virus encoding no transgene or the viral suspension buffer. Animals were specifically not given anti-inflammatory drugs to impede the well-known immunopathologic response to recombinant adenoviral administration. Serum chemistries and hematological parameters were monitored. Rats were subjected to complete gross necropsy and selected tissues were evaluated by histopathology. Most clinical chemistry and hematology values were within normal ranges; however, evidence of inflammation (e.g., elevated lactic dehydrogenase, total leukocyte count) was seen. Gross pathology was normal, as was histopathology, excepting rare focal areas of necrosis. The results show that intrasalivary gland or intravenous AdhAQP1 administration leads to low levels of toxicity in rats. [ABSTRACT FROM AUTHOR]

An abstract of the article "Transgenic Vasoactive Intestinal Peptide Shows Local Disease Modifying Effects in a Murine Model of Sjögren's Syndrome," by Beatrijs M. Lodde and colleagues is presented.

An abstract of the article "Long-Term Transgene Expression with a Second Generation Hybrid AdenoRetroviral Vector," by Changyu Zheng, Weitan Zhang, Joseph M. Vitolo, Bruce J. Baum and colleagues is presented.

An abstract of the article "The Effect of Serine Protease Inhibitor 6 (SPI-6) Gene Transfer on a Mouse Model of Sjögren's Syndrome," by Fumi Mineshiba, Beatrijs M. Lodde, Jianghua Wang, Livia A. Casciola-Rosen, Antony Rosen, and Bruce J. Baum is presented.

An abstract of the article "Long-Term Rapamycin Control of Transgene Expression in Mouse Salivary Glands in a Single AAV Vector," by Jianghua Wang, Antonis Voutetakis, Milton Papa, Victor M. Rivera, Tim Clackson, Beatrijs M. Lodde, Fumi Mineshiba and Bruce J. Baum is presented.

The treatment of patients with head and neck cancers typically includes ionizing radiation (IR). A significant consequence of this is the irreversible damage to salivary glands in the IR field. Without saliva, these patients suffer considerable morbidity, including oral infections, mucositis, dysphagia, as well as frank discomfort. Currently, there is no adequate treatment for this condition. Previously (Delporte et al, PNAS, 1997; Shan et al, Mol Ther, 2005), we showed that serotype 5 adenoviral (Ad5) -mediated transfer of the human aquaporin-1 (hAQP1) cDNA, via AdhAQP1, resulted in a restoration of near normal salivary flow to both rat submandibular and minipig parotid glands four months following IR.In preparation for clinical studies testing this strategy, we conducted a toxicology study with AdhAQP1 in Fischer 344 rats over a 13-week period. Herein, we describe the assessment of transgenic hAQP1 expression in targeted salivary glands, as well as the neutralizing antibody responses to vector delivery. A total of 100 animals per gender were studied. On day zero, animals received either vehicle (diluent buffer), or AdhAQP1 (2 × 10e8, 8 × 10e9 or 2 × 10e11 particle units; pu) via retroductal submandibular gland delivery. Five animals per gender and dosage group were sacrificed on days 3, 15, 29, 57 and 92. Protein from submandibular gland aqueous extracts (1000×g supernatants) was slot blotted onto nitrocellulose filters, and hAQP1 detected with a polyclonal antibody. Neutralizing antibodies were measured as the dilution of serum that resulted in 50% inhibition of the transduction of 293 cells with an Ad5 vector encoding luciferase, AdRSVLuc (MOI = 10).All vector-treated animals survived until scheduled sacrifice, and in general toxicological observations were comparable to findings previously reported with similar Ad5 vectors expressing different transgenes (O'Connell et al, J Oral Pathol Med, 2003; Zheng et al, Oral Dis, 2006). Transgene expression was readily seen in day 3 samples and was detectable in most high dose samples through the day 15-time point. Thereafter (days 29, 57, 92), slot blot results from vector-treated animals were not different from those of vehicle-treated animals. Additionally, on day 3, the expression of transgene was vector dose-dependent. None of the vehicle-treated rats showed the presence of neutralizing antibodies to Ad5 vectors in their sera. However, by day 29, four animals in the 2 × 10e8 pu vector dosage group exhibited low levels of serum neutralizing antibodies (2/gender; 1:4, 1:8, 1:8, 1:16), while all animals receiving 8×10e9 pu AdhAQP1 were positive for neutralizing antibodies (1:64 – 1:256; median 1:128). Similarly, all animals receiving 2×10e11 pu AdhAQP1 were positive for neutralizing antibodies on day 29, but with much higher titers (1:256 – 1:2048; median 1:1024). These results show that following AdhAQP1 administration to rat submandibular glands, hAQP1 protein is expressed, and anti-Ad5 neutralizing antibodies are produced, in a dose and time-dependent manner.Molecular Therapy (2006) 13, S113–S113; doi: 10.1016/j.ymthe.2006.08.351 [ABSTRACT FROM AUTHOR]

An abstract of the article "Microvessel Injury and Irradiation Damage in Salivary Glands," by Ana Paola P. Cotrim, Jianghua Wang, Antonis Voutetakis, Anastasia L. Sowers, James B. Mitchell and Bruce J. Baum is presented.

Marie Ussing Nylen was a trail blazing scientist and administrative leader at the US National Institutes of Health. She accomplished this when it was extremely difficult for a woman to do so. She was also a whole person - a wife, mother, and talented athlete, that is, a well-rounded person by any definition. She was a gift to dental and oral science, as well as to those fortunate enough to know and work with her., (Published 2022. This article is a U.S. Government work and is in the public domain in the USA.)

For many years, our research group worked to develop gene transfer approaches for salivary gland disorders that lacked effective conventional therapy. The purpose of this chapter is to describe and update key methods used in this process. As described in our original chapter from the 2010 volume, we focus on one clinical condition, irradiation-induced salivary hypofunction, and address the choice of transgene and vector to be used, the construction of recombinant viral vectors, how vector delivery is accomplished, and methods for assessing vector function in vitro and in an appropriate animal model.

Purpose: Clinician-scientists are considered an endangered species for many reasons, including challenges with establishing and maintaining a career pipeline. Career outcomes from yearlong medical and dental students' research enrichment programs have not been well determined. Therefore, the authors assessed career and research outcome data from a cohort of participants in the National Institutes of Health (NIH) Clinical Research Training Program (CRTP)., Method: The CRTP provided a yearlong mentored clinical or translational research opportunity for 340 medical and dental students. Of these, 135 completed their training, including fellowships, from 1997 to January 2014. Data for 130 of 135 were analyzed: time conducting research, types of public funding (NIH grants), and publications from self-reported surveys that were verified via the NIH Research Portfolio Online Reporting Tools Web site and PubMed., Results: Nearly two-thirds (84 of 130) indicated that they were conducting research, and over half of the 84 (approximately one-third of the total cohort) spent more than 25% of time conducting research. Of those 84, over 25% received grant support from the NIH, and those further in their careers published more scholarly manuscripts., Conclusions: Data suggest that the CRTP helped foster the careers of research-oriented medical and dental students as measured by time conducting research, successful competition for federal funding, and the publication of their research. Longer follow-up is warranted to assess the impact of these mentored research experiences. Investments in mentored research programs for health professional students are invaluable to support the dwindling pipeline of biomedical researchers and clinician-scientists.