Identification of Stem Cells in the Secretory Complex of Salivary Glands.

Salivary glands have an essential secretory function for maintaining oral and overall health. The epithelial compartment of the gland is composed of several highly specialized cell types that cooperate to secrete and deliver saliva to the oral cavity. The mouse submandibular gland has been used as a model for major salivary glands in human. The secretory complex in this model is composed of 2 secretory compartments, including acini and granular ducts connected by intercalated ducts. Contractile myoepithelial cells surround the secretory complex to facilitate salivary flow. Whether differentiated cells in the secretory complex are maintained by self-duplication or contribution from stem cells has remained an open question. Here, in analyzing the expression of basal cytokeratin (K) 14 in the secretory complex, we discovered a subset of K14(+) ductal cells in the intercalated ducts of the adult gland. These cells are distinct from the K14-expressing basal/myoepithelial cells, proliferate at a significantly higher rate than any other epithelial cell type in the gland, and reside in a spatially defined domain within the intercalated duct. Using inducible genetic lineage tracing, we show that K14(+) ductal cells represent a long-lived yet cycling population of stem cells that are established during development and contribute to the formation and maintenance of the granular ducts throughout life. Our data provide direct evidence for the existence of stem cells contributing to homeostasis of salivary glands, as well as new insights into glandular pathobiology.

Effect of biotin and pantothenic acid on performance and concentrations of avidin-binding substances in blood and milk of lactating dairy cows.

We hypothesized that pantothenic acid reduces the absorption of biotin in lactating dairy cows. Therefore, the objective of this study was to evaluate the plausible interaction between biotin and pantothenic acid on production performance and concentration of avidin-binding substances (ABS), an indicator of biotin concentration, in blood and milk of lactating dairy cows. Eight primiparous and 16 multiparous Holstein cows were assigned to 1 of 4 diet sequences in a replicated 4×4 Latin square design with 18-d periods. Cows were housed in a freestall barn and fed once daily (0730 h) by means of a Calan gate system (American Calan Inc., Northwood, NH). Treatments consisted of a control diet that contained no B-vitamins, a biotin diet that contained 0.87 mg of biotin per kilogram of dry matter (DM), a pantothenic acid diet that contained 21 mg of pantothenic acid per kilogram of DM, and a biotin plus pantothenic acid diet that contained 0.87 mg of biotin and 21 mg of calcium pantothenic acid per kilogram of DM. Four different concentrates were prepared in a commercial feed mill. These concentrates were mixed with corn silage and grass hay and delivered ad libitum as a total mixed ration. Biotin supplementation did not affect DM intake, milk yield, or milk fat, protein, lactose, and milk-urea-nitrogen concentrations. Fat, protein, and lactose yields were not affected by treatments. The fat-to-protein ratio was <1 and similar among all treatments. Biotin supplementation did not increase the concentration of ABS in plasma. The supplementation of pantothenic acid did not affect the concentration of ABS in plasma when either supplemented alone or in combination with biotin. Biotin supplementation increased the concentration of ABS in milk relative to control. Contrary to our hypothesis, the supplementation of pantothenic acid did not decrease the concentration of ABS in milk relative to the control. When cows were supplemented with both biotin and pantothenic acid, the concentration of ABS in milk was similar to that of cows supplemented with biotin alone. In conclusion, pantothenic acid did not affect the concentrations of ABS in plasma and milk, suggesting that increasing dietary supply of pantothenic acid did not inhibit biotin absorption.

The metabolism and pharmacokinetics of phospho-sulindac (OXT-328) and the effect of difluoromethylornithine.

BACKGROUND AND PURPOSE: Phospho-sulindac (PS; OXT-328) prevents colon cancer in mice, especially when combined with difluoromethylornithine (DFMO). Here, we explored its metabolism and pharmacokinetics. EXPERIMENTAL APPROACH: PS metabolism was studied in cultured cells, liver microsomes and cytosol, intestinal microsomes and in mice. Pharmacokinetics and biodistribution of PS were studied in mice. KEY RESULTS: PS undergoes reduction and oxidation yielding PS sulphide and PS sulphone; is hydrolysed releasing sulindac, which generates sulindac sulphide (SSide) and sulindac sulphone (SSone), all of which are glucuronidated. Liver and intestinal microsomes metabolized PS extensively but cultured cells converted only 10% of it to PS sulphide and PS sulphone. In mice, oral PS is rapidly absorbed, metabolized and distributed to the blood and other tissues. PS survives only partially intact in blood; of its three major metabolites (sulindac, SSide and SSone), sulindac has the highest C(max) and SSone the highest t(1/2) ; their AUC(0-24h) are similar. Compared with conventional sulindac, PS generated more SSone but less SSide, which may contribute to the safety of PS. In the gastroduodenal wall of mice, 71% of PS was intact; sulindac, SSide and SSone together accounted for <30% of the total. This finding may explain the lack of gastrointestinal toxicity by PS. DFMO had no effect on PS metabolism but significantly reduced drug level in mouse plasma and other tissues. CONCLUSIONS AND IMPLICATIONS: Our findings establish the metabolism of PS define its pharmacokinetics and biodistribution, describe its interactions with DFMO and largely explain its gastrointestinal safety.

Phospho-ibuprofen (MDC-917) incorporated in nanocarriers: anti-cancer activity in vitro and in vivo.

BACKGROUND AND PURPOSE: Phospho-ibuprofen (P-I; MDC-917) inhibits the growth of colon cancer in mice. Here, we investigated the use of nanocarriers to improve its pharmacokinetics (PKs) and anti tumour efficacy. EXPERIMENTAL APPROACH: The cellular uptake and cytotoxicity of P-I encapsulated into liposomes and micelles, and its in vitro metabolic stability, were determined in cultures of human colon adenocarcinoma cells. The performance of liposomal P-I was further evaluated in PK studies in mice, and in a model of colon cancer xenografts in nude mice. KEY RESULTS: Liposomal P-I and micellar P-I showed significantly enhanced cellular uptake in the colon cancer cells. Liposomal P-I also demonstrated increased cytotoxicity in vitro. Free P-I was metabolized rapidly to ibuprofen in the presence of purified esterases. In contrast, liposomal P-I, and to a lesser extent micellar P-I, was resistant to esterase-mediated hydrolysis. In mice, liposomal P-I partially protected P-I from hydrolysis in the circulation, and improved the biodistribution of intact P-I and its metabolites compared to free P-I. Liposomal P-I was more effective at inhibiting the growth of human colon cancer xenografts in mice, which may be explained on the basis of its improved PK profile compared to free P-I. CONCLUSIONS AND IMPLICATIONS: Liposome encapsulation of P-I partially protected P-I from esterase-mediated hydrolysis in mice, enhanced the cytotoxicity and bioavailability of P-I and increased its efficacy at inhibiting the growth of human colon cancer xenografts. These results indicate that liposomes are suitable nanocarriers for the delivery of P-I, and that the anti-tumour potential of liposomal P-I merits further evaluation.

Morphine reduces herpes simplex virus-1 pathogenesis in the murine flank.

Here we investigate the effect of morphine on herpes simplex virus-1 (HSV-1) pathogenesis using a murine flank scarification model. Murine flank scarification with HSV-1 results in primary lesions at the site of inoculation within three days and lesions at secondary sites within four days. The lesions are scored based on lesion size. Applying 0.1 mM morphine to the skin one-day post inoculation tested the effect of morphine on the formation of the herpes lesion. On days three through five, mice treated with morphine developed lesions with scores half of that observed in untreated animals, however, skin viral titers on these days were equivalent. Further, 1.0 microM morphine did not effect the replication rate of HSV-1 in Vero cells. Taken together, these data suggest the morphine reduced HSV-1 pathogenesis by modifying the host response to HSV-1 infection and not by reducing viral replication rates.