Primary culture of human labial salivary gland acini.
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Adult↗
Biomedical subjects
R S Redman
Publications and source records attributed to R S Redman.
Effects of oxygen, insulin, and glucagon concentrations on rat submandibular acini in serum-free primary culture.
The objective of these studies was to develop serum-free culture conditions for dissociated acini from rat submandibular glands. Acini were isolated from the submandibular glands of 42-46 d old rats and cultured on reconstituted rat tail collagen containing laminin in 1:1 Ham's F12 and Dulbecco's media, supplemented with BSA, transferrin, insulin, T3, EGF, dexamethasone, retinoic acid, carbamylcholine, and trace elements, and gassed with 50% O2. The acini became partly embedded in the collagen gel and rapidly enlarged throughout the first 22 d of culture, maintaining modest seromucous acinar differentiation, as judged morphologically and by mucin secretion. Parallel cultures then were grown under 20, 35, 50, and 65% O2, and evaluated morphologically and by DNA content. Growth and retention of seromucous acinar characteristics were best with 35% O2, but lipid accumulation and cell death were unacceptably high. A spectrum of concentrations of insulin and glucagon then were tried. With 0.05 micrograms/ml insulin, cellular growth and organization were orderly, lipid accumulations were not excessive, and moderate differentiation was retained through 15 d of culture. With more than 0.1 microgram/ml insulin added to or subtracted from the optimum, the detrimental effects recurred. Addition of sufficient glucagon counteracted the effects of both optimum and excessive concentrations of insulin. We now have achieved an orderly growth of moderately differentiated rat submandibular acini for 15 d in serum-free primary culture.
Animals↗
Determinants of potency and temperature-dependent function in the Aplysia bag cell peptides.
Structure-activity relationships were determined for the natural bag cell peptides (BCPs) and for a series of synthetic analogues in terms of their ability to stimulate (at 30 degrees C) and to inhibit (at 15 degrees C) bag cell adenyl cyclase. We found that the core RLRF motif shared by all these peptides is active in this assay, and is stimulatory. The histidine residue C-terminal to this motif in beta-BCP is superfluous in this respect. An electronegative residue C-terminal to RLRF is sufficient to induce temperature-dependent function. The Ala-Pro pair that is N-terminal to this motif in alpha-BCP increases potency, but does not alter function.
Adenylyl Cyclase Inhibitors↗
Peripheral ameloblastoma with unusual mitotic activity and conflicting evidence regarding histogenesis.
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Aged↗
Temporal and spatial expression of laminin, collagen types IV and I and alpha 6/beta 1 integrin receptor in the developing rat parotid gland.
We have examined the temporal expression and cellular localization of the genes and proteins for the extracellular matrix (ECM) proteins laminin (B1, B2 and A chain), collagen types alpha 1 (IV) and alpha 1 (I) and the integrin receptor complex alpha 6/beta 1, during parotid gland postnatal development. Laminin B1 and B2 isoforms and collagens alpha 1 (IV) and alpha 1 (I) mRNA steady-state levels were highest at ages 0, 7 and 14 days after birth and declined to the adult (90 days) level at 21 days and older. Laminin A chain transcripts were not detected at any age. Collagen alpha 1 (IV) and laminin were localized in the basal membrane of the developing acinar and ductal cells, while collagen alpha 1 (I) was localized in the stroma surrounding the cells. The amounts of these ECM components were high at the early stages of development and lower at later times. The pattern of expression of the alpha 6/beta 1 integrin genes during development was similar to those of laminin and collagens alpha 1 (IV) and alpha 1 (I). Accumulations of mRNA were high at 0, 7 and 14 days after birth and lower at 21 days and older. High levels of beta 1 integrin were localized in the developing acinar and ductal cell membranes at early ages (7 days); lower amounts were present in the same distribution pattern at later stages of gland development.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Reduction by intracellular calcium chelation of acetylcholine secretion without occluding the effects of adenosine at frog motor nerve endings.
1. The calcium chelators bis-(aminophenoxy)ethane-tetraacetic acid (BAPTA) or dimethyl-BAPTA (DMBAPTA) were introduced into the cytoplasm of frog motor nerve endings by use of the AM loading technique. The effects of intracellular Ca2+ chelation was studied on quantal acetylcholine (ACh) release and on the action of adenosine. 2. Intracellular BAPTA or DMBAPTA prevented the increases in quantal ACh secretion normally evoked by caffeine. 3. Intracellular DMBAPTA decreased the number of ACh quanta released by individual nerve impulses and virtually eliminated the fast phase of facilitation in response to paired nerve impulses. 4. Adenosine reduced both spontaneous and evoked secretion of ACh quanta with its usual potency and efficacy in the presence of intracellular DMBAPTA. Adenosine had no significant effect on facilitation. 5. The results, which suggest that adenosine and intracellular DMBAPTA reduce ACh secretion by different mechanisms, are consistent with the hypothesis that adenosine inhibits ACh release by reducing the ability of Ca2+ to promote ACh secretion from frog motor nerve endings.
Acetylcholine↗
Decrease in calcium currents induced by aminoglycoside antibiotics in frog motor nerve endings.
1. The effects of the aminoglycoside antibiotics, streptomycin, neomycin and gentamicin were examined on perineural currents and evoked acetylcholine (ACh) release at frog motor nerve endings. 2. In the standard solutions used previously to measure Ca2+ currents, streptomycin reduced the peak amplitude of the Ca2+ component of the perineural current. 3. In a solution in which changes in both Ca2+ currents and evoked ACh release can be recorded simultaneously, both Ca2+ currents and evoked ACh release were reduced by aminoglycosides in the potency order neomycin > streptomycin > gentamicin. This potency sequence is similar to that reported previously for these agents as inhibitors of neurally-evoked contractions of mammalian skeletal muscle. 4. These data suggest that the presynaptic inhibitory effects of aminoglycoside antibiotics at the neuromuscular junction occur as a consequence of a reduction in Ca2+ currents in the motor nerve terminal.
Acetylcholine↗
Chronology of peroxidase activity in the developing rat parotid gland.
The course of development of salivary peroxidase, an enzyme that has an important role in oral defense mechanisms, has been well documented in rat submandibular glands. However, the only report on salivary peroxidase activity in the other major salivary glands of the rat has been a cytochemical study of the adult parotid gland. In the present investigation, the accumulation of salivary peroxidase activity in developing parotid glands of rats was followed both biochemically and cytochemically. Specific activity (units per mg protein) attributable to salivary peroxidase began at 1 day after birth, then rose rapidly but unevenly, with peaks at 21 and 70 days, and no difference between the sexes at any age. Activity per gland increased progressively to 42 days in both sexes and was significantly higher in males at 70 days. The cytochemical observations on peroxidase activity localized to the rough endoplasmic reticulum and secretory granules of the developing acini were well correlated with the biochemical findings. Peroxidase-negative cells occurred in immature acini at 1 and 7 days, but only in the intercalated ducts thereafter. This observation suggests that the acini are a source of some of the ductal cells, at least during early postnatal development. The developmental pattern of specific activity differed from those of other rat parotid secretory enzymes, indicating that control of their synthesis during development is noncoordinate. The patterns of specific activity of the parotid and submandibular glands were complementary, suggesting that their combined secretions may supply biologically significant peroxidase activity to the oral cavities of rats throughout postnatal development.
Animals↗
Temperature-dependent stimulation and inhibition of adenylate cyclase by Aplysia bag cell peptides.
The bag cell peptides (alpha-, beta-, and gamma-BCP) are secreted by the neuroendocrine bag cells of Aplysia, and provide feedback modulation of bag cell excitability and cAMP levels. We report here that if 200-500 mM NaCl is included in the assay buffer, the BCPs alter adenylate cyclase activity in a manner consistent with their effects on cAMP levels in intact bag cells. Specifically, beta-BCP and the related peptide A from the atrial gland stimulate the enzyme, while the effects of alpha-BCP(1-7) and gamma-BCP are temperature-dependent, stimulating at 30 degrees C and inhibiting at 15 degrees C. Both stimulation and inhibition require GTP, suggesting mediation by Gs and Gi. The ionic requirements of stimulation and inhibition differ: Cl- is necessary to support stimulation, but not inhibition. Moreover, pertussis toxin blocks inhibition, but does not affect stimulation. These results suggest that the temperature-sensitive mechanism lies upstream from the G-proteins in the signal transduction pathway.
Adenylyl Cyclase Inhibitors↗
A selective adenosine antagonist (8-cyclopentyl-1,3-dipropylxanthine) eliminates both neuromuscular depression and the action of exogenous adenosine by an effect on A1 receptors.
The effect of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective A1 adenosine receptor antagonist, was studied at frog motor nerve endings in the hope of determining whether the inhibitory effects of exogenous or endogenous adenosine on neurotransmitter release are mediated by an A1 receptor or the postulated prejunctional "A3 receptor." These putative A3 receptors have been reported to have a lower affinity for DPCPX (>> 1 nM) than A1 receptors (50-190 pM) and have been linked to changes in Ca2+ translocation. The affinity of DPCPX as an antagonist of exogenous adenosine at frog motor nerve endings was calculated by using the Schild equation and found to range from 25 to 200 pM (n = 12). These values are consistent with the presence of A1 receptors. The effect of endogenous adenosine as a mediator of prejunctional neuromuscular depression produced by repetitive nerve impulses was fully reversed by 100 pM DPCPX. Neither prejunctional neuromuscular depression produced by endogenous or exogenous adenosine nor the reversal of depression by DPCPX was associated with changes in nerve terminal Ca2+ currents. The results demonstrate that endogenous or exogenous adenosine mediates neuromuscular depression in the frog, via an A1 receptor.
Acetylcholine↗
Vitamin E in the treatment of chemotherapy-induced mucositis.
PURPOSE: To determine the efficacy of vitamin E in the treatment of chemotherapy-induced mucositis in patients with malignancy. PATIENTS AND METHODS: A randomized, double-blind, placebo-controlled study was performed to evaluate the efficacy of topical vitamin E in the treatment of oral mucositis in patients receiving chemotherapy for various types of malignancy. A total of 18 patients, 17 of whom had solid tumors and one with acute leukemia, were included in this study. Lesions were observed daily prior to and 5 days after topical application of either vitamin E or placebo oil. RESULTS: Six of nine patients receiving vitamin E had complete resolution of their oral lesions. In eight of nine patients who received placebo, complete resolution of their oral lesions was not observed. This difference is statistically significant (p = 0.025 by Fisher's exact test). No toxicity was observed in this study. CONCLUSION: These results suggest that vitamin E may be an effective therapy in patients with chemotherapy-induced mucositis.
Administration, Topical↗
Effects of clonidine on the calcium content and morphology of rat salivary glands.
These effects were examined with and without pretreatment of animals with reserpine and the adrenergic antagonists prazosin (alpha 1), yohimbine (alpha 2) and propranolol (beta). The effects of clonidine on glandular concentrations of norepinephrine and dopamine also were examined. These effects were compared with those of xylazine, a presynaptic alpha 2-adrenergic agonist. A single, high dose of clonidine followed by an overnight fast caused marked increases in calcium content and acinar secretory granules in the submandibular and sublingual glands, similar to those caused by reserpine. However, the calcium content of the parotid gland was not altered by clonidine, although there seemed to be a modest increase in acinar secretory granules. The clonidine-induced increase in submandibular calcium content could not be attributed to any adrenergic receptor activity since it was not blocked by either alpha- or beta-adrenergic antagonists. Unlike reserpine, clonidine did not affect catecholamine concentrations in the parotid and submandibular glands. Pretreatment with reserpine did not significantly alter the clonidine-induced increase in submandibular calcium content. It is likely that the greater accumulation of acinar secretory granules is related to the increased calcium stores of the glands in clonidine- and/or reserpine-treated rats. The large differences in calcium content among the three glands might be attributable, in part, to differences in the calcium-binding capacity of their secretory granules. Possible mechanisms for the clonidine effects on salivary-gland calcium include disturbances in membrane-associated pools or gating mechanisms for calcium, which need further study.
Animals↗
Evaluation of the carcinogenic potential of toluidine blue O in the hamster cheek pouch.
Toluidine blue O has been shown to have clastogenic and mutagenic effects when tested in vitro, suggesting that it may be a carcinogen. Because this might compromise its use for cancer screening, the carcinogenic potential of this dye was investigated in the hamster cheek pouch, an established in vivo carcinogenesis model. Male hamsters were divided into seven groups at age 5 weeks. The right pouches of four groups were painted three times weekly with 2% toluidine blue or the vehicle for toluidine blue, in conjunction with submaximal applications of 9,10-dimethyl-1,2-benzanthracene (DMBA) (groups II and III, 0.5% twice weekly), and groups IV and V, 0.1% three times weekly). The right pouches of two groups received DMBA only (group I, 0.5% three times weekly, the standard maximal amount, and group VI, 0.1% three times weekly). Group VII received toluidine blue (right pouches) and toluidine blue vehicle (left pouches) three times weekly. The extent of carcinomas and other abnormalities (scored histologically) did not differ among groups receiving the same amount of DMBA with and without toluidine blue or vehicle, and no abnormalities were seen in the pouches from group VII. These results demonstrate no effect of toluidine blue as a carcinogen, cocarcinogen, or promoter.
9,10-Dimethyl-1,2-benzanthracene↗
ProELH-related peptides: influence on bag cell cAMP levels.
ProELH is the prohormone to the bag cell egg-laying peptide of Aplysia. In addition to containing the structure of the hormone (ELH) itself, proELH also contains several other secreted peptides: AP (acidic peptide) and alpha-, beta-, and gamma-bag cell peptides (BCPs). The BCPs, ranging in length from 5 to 9 amino acids, are structurally similar in that they all contain the sequence Arg-Leu-Arg-Phe. An additional peptide from the atrial gland, Atrial A, also contains this sequence. The BCPs previously have been reported to have direct feedback (autocrine) effects on the bag cells, including electrophysiological excitation and inhibition. Moreover, some of these effects are temperature-dependent. The autocrine functions of these peptides were explored here by investigating their effects on bag cell cAMP levels. In addition, we monitored the effects of Atrial A, as well as ELH and AP, which are proELH products that do not have sequence homology with the BCPs. While ELH and AP have no effect on bag cell cAMP levels, the other peptides fall into two functional classes. alpha- and gamma-BCP produce an elevation of cAMP levels at 20 degrees and a depression at 15 degrees C. The elevation in cAMP is sensitive to low Ca2+/high Mg2+. beta-BCP and Atrial A elevate cAMP levels independently of temperature, and are insensitive to low Ca2+/high Mg2+. Our results suggest that there may be multiple bag cell receptors for these peptides with the Arg-Leu-Arg-Phe sequence representing a receptor-recognition motif.
Amino Acid Sequence↗
Reciprocal expression of c-jun, proline-rich protein and amylase genes during rat parotid salivary gland development.
We have investigated the temporal expression and cellular localization of the c-jun proto-oncogene and two major rat parotid gland secretory protein genes, PRP (proline-rich protein) and amylase, during postnatal development. c-jun mRNA steady-state levels increased at days 1, 7 and 14 after birth and decreased to basal levels at 21 days and older. PRP mRNA was first detected at 14 days and abruptly increased to adult levels at day 21. Amylase transcripts were first seen at day 7 and progressively increased to adult levels by 28 days. In situ hybridization demonstrated c-jun mRNA accumulation in the differentiating acinar cells and the ducts. The c-jun mRNA accumulation with time corresponds with the proliferative activity reported to occur in these two cellular populations. PRP transcripts were present exclusively in the well differentiated acinar cells while the accumulation of amylase mRNA corresponded to the progressive commitment of parotid cells to acinar differentiation. Our data suggest that during the postnatal development of the rat parotid gland: (a) c-jun expression associates with parotid gland proliferation and precedes the expression of PRP and amylase genes, and (b) activation of PRP and amylase genes is not concomitant and apparently occurs only in differentiating acinar cells.
Age Factors↗
Temperature-dependent peptidergic feedback: potential role in seasonal egg laying in Aplysia.
alpha-Bag cell peptide (alpha-BCP), one of the secretory products of the neuroendocrine bag cells in Aplysia, has been reported by various investigators to have either excitatory or inhibitory feedback effects. Though conflicting, these results may be explained by the difference in temperature at which the experiments were performed. Because egg laying in this animal is temperature dependent, the alteration in function of this peptide by temperature may offer a possible molecular basis for the seasonal regulation of egg laying. This hypothesis was investigated by assessing the feedback actions of alpha-BCP at various temperatures. At 15 degrees C, alpha-BCP hyperpolarized bag cells, shortened the duration of synaptically evoked bag cell discharges, and reduced the number of action potentials per discharge. However, at 20 degrees C, the peptide depolarized bag cells, lengthened discharges, and increased the number of action potentials per discharge. A temperature-dependent influence on bag cell cAMP levels may underlie these effects, because alpha-BCP reduced basal cAMP levels in intact bag cells at temperatures of 15 degrees C and below, while at 17-22 degrees C it increased these levels. However, the inhibitory effects of alpha-BCP on stimulated adenylate cyclase activity in bag cell homogenates were not temperature dependent. Moreover, a low-Ca2+/high-Mg2+ solution abolished alpha-BCP's ability to increase bag cell cAMP levels at 20 degrees C. This suggests that the peptide may evoke the secretion of an excitatory modulator at the higher temperature. These results imply that alpha-BCP is autoinhibitory at typical winter temperatures, but becomes autoexcitatory as ocean temperature rises in the summer. Thus, the peptide may function in coordination with other factors to regulate egg laying in response to seasonal temperature variations.
1-Methyl-3-isobutylxanthine↗
Physostigmine-induced salivary secretion in the rat.
The purpose of this study was to see if physostigmine, a reversible cholinesterase inhibitor, affects the secretion and composition of saliva of the major salivary glands of the rat. Low doses of physostigmine did not elicit secretion. At higher doses there was significant flow from the parotid and submandibular glands within 5 min; however, no sublingual secretion was observed. The submandibular flow rate was highest for the first 5 min, then declined rapidly. The parotid flow rate initially was one-fifth of the maximum submandibular rate and then gradually decreased. The concentrations of Ca, Na and K of physostigmine-induced parotid saliva, and the Na of submandibular saliva, were similar to those with carbachol stimulation. The Ca and K concentrations of submandibular saliva were significantly higher than with carbachol or parasympathetic stimulation, and resembled those of alpha-adrenergic stimulation. The protein concentrations of physostigmine-evoked saliva from both glands were similar. The amylase activity of physostigmine-evoked parotid saliva was much higher than that of carbachol or parasympathetic stimulation. Physostigmine-evoked secretion was completely blocked by atropine, a cholinergic antagonist, and by reserpine, partially blocked by phentolamine, an alpha-adrenergic antagonist and not affected by surgical sympathectomy. Morphologically, physostigmine resulted in a moderate decrease in the number of acinar, but not ductal, secretory granules of both the parotid and submandibular glands, while the sublingual gland was unaffected. Numerous patches of parotid acini also developed vacuoles or vesicles. These results suggest that physostigmine-induced salivary secretion is mediated primarily by direct effects on cholinergic and alpha-adrenergic receptors.
Animals↗
Alpha-bag cell peptide inhibits bag cell adenylate cyclase via a GTP-dependent mechanism.
alpha-Bag cell peptide (alpha-BCP), one of several secreted peptides encoded in the precursor to the egg-laying hormone (proELH) of the neurosecretory bag cells of Aplysia, has been variously reported to have autoexcitatory or autoinhibitory effects on the cells which secrete it. Since we had found previously that alpha-BCP reduces stimulated cAMP levels in intact bag cells, an effect that would be consistent with electrophysiological inhibition, we investigated the direct effect of the peptide on adenylate cyclase in bag cell membrane preparations. alpha-Bag cell peptide did not affect basal adenylate cyclase activity, but reduced forskolin-stimulated activity by about 30%. The potency of the peptide in this assay was within the range reported for observable physiological effects: half-maximal inhibition was seen at approximately 100 nM peptide. Both basal and forskolin-stimulated enzyme activity were dependent on GTP, and the inhibitory effect of alpha-BCP was inversely dependent on the nucleotide. The non-hydrolyzable analogue, GTP-gamma-S, stimulated both basal and forskolin-stimulated enzyme activity and enhanced alpha-BCP's effect to the extent that the peptide completely inhibited forskolin's stimulation of the enzyme. The peptide's effect could be blocked by pretreatment with pertussis toxin. We conclude that alpha-BCP inhibits bag cell adenylate cyclase, an effect which is consistent with an autoinhibitory role in bag cell function. Moreover, this inhibition appears to be mediated by a GTP-binding protein.
Adenylate Cyclase Toxin↗