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Biomedical subjects

C K Yeh

Publications and source records attributed to C K Yeh.

At least 37 records · Page 2Linked to original sources
PubMed1992

Differential expression of early response genes, c-jun, c-fos, and jun B, in A5 cells.

We examined the expression of c-fos, c-jun, and jun B after activation of different signal transduction pathways in the A5 rat salivary epithelial cell line. Stimulation of beta-adrenergic receptors by isoproterenol, or addition of 8-bromoadenosine 3',5'-cyclic monophosphate, induces the expression of c-fos and jun B by a protein kinase A-mediated pathway. Phorbol 12-myristate 13-acetate (PMA) induces the expression of all three genes, but with different kinetics. While c-fos and jun B mRNA levels increase early (1 h) after stimulation and transiently, those of c-jun remain higher than control even after stimulation for 8 h and return to basal levels by 24 h. Inhibitors of protein kinase C block the effect of PMA on c-fos, c-jun, and jun B expression, indicating that these genes are also regulated by a protein kinase C-mediated mechanism in A5 cells. Increases in cytosolic Ca2+ by A23187 or ionomycin induce only the expression of c-fos gene. This induction is abolished when A5 cells are loaded with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid before treatment with the ionophores, or when serum is excluded from the incubation medium. Exclusion of serum from the medium does not change the effects of isoproterenol or PMA on c-fos, c-jun, or jun B. These results strongly suggest that serum factors act synergistically with Ca2+ to induce c-fos expression in A5 cells. The studies presented here indicate that different signal transduction pathways operate in A5 cells for the induction of c-fos, c-jun, and jun B genes.

Animals↗
PubMed1992

Human immunodeficiency virus (HIV) and HIV infected cells in saliva and salivary glands of a patient with systemic lupus erythematosus.

A young woman with systemic lupus erythematosus (SLE) was infected with human immunodeficiency virus 1 (HIV-1) and about 6 years later developed persistent bilateral parotid gland enlargement. It was unclear whether this represented salivary gland involvement as a component of her SLE (secondary Sjögren's syndrome) or the initial clinical manifestation of her HIV-1 infection. HIV proviral DNA was found in individual salivary glandular secretions and in whole saliva. Additionally, cells positive for HIV RNA were isolated from whole saliva. A parotid gland biopsy revealed infiltrating lymphocytes containing large amounts of HIV RNA.

Adult↗
PubMed1992

Further studies of salivary inhibition of HIV-1 infectivity.

An HIV-1/ATH8-cell cytopathic system was used to characterize the previously reported anti-HIV-1 activity of human saliva. Inhibitory activity was demonstrated by monitoring viable cell counts, HIV-1 p24 core antigen, and reverse transcriptase levels. Nonfiltered whole saliva, sterilized by irradiation, protected the ATH8 cells from HIV-1 infection. When HIV-1/saliva mixtures were filtered following incubation, the quantity of virus was significantly less (approximately 50%) than in HIV-1/media-filtered controls, suggesting that salivary aggregation and/or agglutination may be involved in the inhibitory activity. However, a sufficient number of apparently morphologically intact viral particles were still present in the HIV-1/saliva filtrates to lead to infection. When saliva was filtered prior to incubation with HIV-1, these filtrates showed substantial inhibitory activity, although reduced compared with that of non-prefiltered saliva. We conclude that saliva likely has several means by which to inhibit HIV-1 infectivity.

Adult↗
PubMed1992

Envelope-specific antibodies in the saliva of individuals vaccinated with recombinant HIV-1 gp160.

HIV-1-specific antibodies have been detected in the saliva of seropositive individuals and may play a role in preventing oral transmission of the virus. We have analyzed saliva samples obtained from HIV-1-seronegative individuals who were immunized with various dosages of a recombinant HIV-1 envelope glycoprotein (gp160) vaccine for the presence of antibodies to HIV-1. Antibodies specific for envelope glycoproteins were detected in saliva from all of the volunteers, with those vaccinated with the higher doses of 640 and 1,280 micrograms showing the strongest responses. Peak salivary antibody titers were obtained 4-14 weeks after vaccination; they then gradually dropped in parallel with serum antibody titers. These envelope-specific antibodies were detected in whole saliva and in submandibular saliva but not in parotid saliva, suggesting that the source of antibodies in saliva is from serum transudation. The class of reactive antibodies was found to be IgG. The HIV-1-specific antibodies in the saliva of vaccinated individuals may offer local protection against HIV-1 infection.

AIDS Vaccines↗
PubMed1991

Characteristics of c-fos and jun B gene expression in A5 cells after beta-adrenoreceptor stimulation and during the cell cycle.

The beta-adrenoreceptor agonist isoproterenol elevates cAMP concentrations in the A5 rat salivary epithelial cell line and rapidly and transiently induces the expression of c-fos and jun B at 30 and 60 min following continuous stimulation of these cells. The induction of both genes is mediated by cAMP. We show here that the inducibility of these genes by isoproterenol or 8-BrcAMP is transcriptionally regulated and short (5 min) incubations of A5 cells with either agent is sufficient to trigger the induction of c-fos and jun B. We also have investigated the expression and inducibility of these genes during the A5 cell cycle. Both c-fos and jun B mRNA are elevated at the early phase of the cell cycle and are detectable throughout the cycle. At different stages of the cell cycle in synchronous A5 cells, both genes are as highly induced by isoproterenol or 8-BrcAMP as in asynchronous A5 cells. These studies provide the first evidence for the transcriptional regulation of c-fos and jun B by beta-adrenergic receptor stimulation or cAMP in an epithelial cell line (A5) and demonstrate the coordinate expression and inducibility of these genes at the different stages of the A5 cell cycle.

Adrenergic beta-Agonists↗
PubMed1991

Detection of proviral sequences in saliva of patients infected with human immunodeficiency virus type 1.

Single samples of saliva collected from 20 human immunodeficiency virus type I (HIV-1) seropositive patients were tested by the polymerase chain reaction for HIV-1 proviral sequences using primers from the long terminal repeat (LTR), gag, and env regions of the virus. Proviral sequences were detected in the saliva of 50% of the patients. Sequential samples of saliva, collected at four different times, from each of six additional patients led to the detection of proviral sequences in 100% of the patients. Since, however, the detection of HIV-1 required not only the highly sensitive polymerase chain reaction, but also multiple samples, it appears that under ordinary circumstances infected cells are present in saliva in low numbers. Although this may explain the lack of transmission of HIV-1 by casual contact through the salivary route to household members and health-care workers, the presence of infected cells in the saliva of a high percentage of patients argues for avoidance of sexually intimate situations involving prolonged and repeated contact with saliva.

Adult↗
PubMed1991

Evidence that M3 muscarinic receptors in rat parotid gland couple to two second messenger systems.

The binding affinities of muscarinic antagonists were compared with their abilities to block carbachol (CCh)-mediated stimulation of Ca2+ mobilization and inhibition of isoproterenol-elicited adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in rat parotid cells. The binding of [3H]quinuclidinyl benzilate (QNB) to membranes was inhibited by antagonists with the following potencies (dissociation constant, nM): atropine (1.1) approximately 4-diphenylacetoxy-N-methylpiperidine methbromide (4-DAMP) (1.6) much greater than pirenzepine (136) greater than 11-[[2-[(diethylamino)methyl-1-piperidinyl]-acetyl]acetyl]-5,11- dihydro-6H-pyrido[2,3-b][1,4]-benzodiazepine-6-one (AF-DX 116) (5,293). AF-DX 116 blocked Ca2+ mobilization and inhibition of cAMP accumulation with low affinities [inhibitory concentration at 50% (IC50) = 3150 and 6,528 nM, respectively], whereas 4-DAMP blocked these responses with considerably higher affinities (IC50 = 4.3 and 11.4 nM, respectively). Schild plots of 4-DAMP and AF-DX 116 antagonism of CCh-stimulated inositol trisphosphate accumulation showed inhibitor constant (Ki) values of 0.85 and 1,585 nM, respectively, whereas Schild plots of 4-DAMP, AF-DX 116, and methoctramine antagonism of CCh-induced inhibition of cAMP accumulation showed Ki values of 1.3, 1,585, and 2,754 nM, respectively. Preincubation of cells with 0.1 mM 3-isobutyl-1-methylxanthine did not prevent the capacity of CCh to inhibit cAMP accumulation. Pertussis toxin blocked the CCh-elicited and Gi-mediated inhibition of cAMP formation. Northern blot analysis showed the presence of mRNA for the M3, but not for the M2, subtype in parotid gland. An immunochemical procedure using m1-m5 specific antibodies was performed in parotid membranes and showed that the m3 receptor accounts for 93% of precipitable receptors. These data suggest that M3 receptors in the rat parotid are coupled to both the stimulation of Ca2+ mobilization and the inhibition of cAMP accumulation.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Influence of beta-adrenergic stimulation on glycosylation of a major, secretory N-linked glycoprotein from rat parotid salivary gland.

beta-Adrenergic stimulation with 10 microM isoproterenol increased the [3H]-mannose/[14C]-leucine ratio (three- to six-fold) of protein extracts in double-radiolabelled rat parotid acinar cells. Characteristics of oligosaccharides in a major parotid glycoprotein (Mr approximately 220,000; gp 220) were studied. Gp 220 from control and experimental cells was endoglycosidase H-insensitive, endoglycosidase F-sensitive and bound both concanavalin A and wheat germ agglutinin. Gp 220 was removed from concanavalin A-Sepharose by sequential elution with 10 mM alpha-methyl glucoside and 0.5 M alpha-methyl mannoside. These findings suggest that (1) oligosaccharides in gp 220 have both a biantennary complex and hybrid oligosaccharide chains, and (2) beta-adrenoreceptor stimulation has little effect on the gross oligosaccharide structures of this glycoprotein.

Animals↗
PubMed1990

Regulation of proto-oncogenes and salivary gland cell proliferation.

The proto-oncogenes c-fos and c-jun express proteins targeted into the nucleus. The fos and jun proteins form a heterodimeric complex that binds to regulatory elements in the promoter region of specific genes to influence their transcription. Through such a mechanism, the fos and jun proteins have been suggested to link extracellular stimuli to short- and long-term functional changes in cells. Recently we have shown that beta-adrenergic receptor stimulation of rat parotid acinar cells in vitro or addition of 8-BrcAMP in a rat submandibular cell line (RSMT-A5) increases the expression of the c-fos gene in a time-dependent manner. Maximal responses were found at 60 min. The expression of the c-fos gene did not correlate with DNA synthesis in either cell type, and c-fos transcripts were undetectable in the glands of animals treated for eight days with isoproterenol. The new data presented here extended our observations to c-jun gene expression in both salivary cell types where a similar pattern of expression for this proto-oncogene was seen. Conversely, treatment of rats with isoproterenol for nine days resulted in the appearance of two c-abl mRNAs of unique size, in addition to the known 5.3-kb c-abl transcripts. The data suggest that beta-adrenergic receptor stimulation or exposure to 8-BrcAMP induces the early expression of the "nuclear proto-oncogenes" c-fos and c-jun before changes are noted in salivary epithelial cell proliferation. Differences in c-abl mRNA size, occurring later, may be associated with the morphological and biochemical changes known to occur in rat parotid glands after chronic beta-adrenoreceptor stimulation.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1989

Kaposi's sarcoma of the parotid gland in acquired immunodeficiency syndrome.

A patient with acquired immunodeficiency syndrome complained of a dry mouth and bilateral swelling of the parotid glands. Kaposi's sarcoma (KS) was found within the tissue of the parotid gland. Although KS is a common manifestation of acquired immunodeficiency syndrome, the presence of KS in the salivary glands is very rare. The human immunodeficiency virus I (HIV-I) genome was not identified in parotid glandular cells or in KS cells in this case, although the virus was detected in infiltrating lymphocytes and in tissue macrophages.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Longitudinal evaluation of major salivary gland function in HIV-1 infected patients.

Parotid and submandibular gland function were evaluated in 12 HIV-1 antibody-positive men at two visits separated by a median interval of 14.5 months (range 6-22 months). Unstimulated and stimulated flow rates, and the concentrations of total protein, lysozyme, albumin and lactoferrin in these secretions, were determined. Parotid and submandibular gland secretions changed in a specific fashion with time. Lysozyme levels in both glandular stimulated secretions showed significant changes (approximately 40% and 70% elevated, between visits, in parotid and submandibular saliva, respectively). In addition, the frequency with which albumin was detected in unstimulated parotid secretions increased with time. These findings support earlier results suggesting the presence of alterations in major salivary gland function following HIV-1 infection. Submandibular gland function appears to manifest these alterations earlier, but with time the parotid secretions show similar changes.

Albumins↗
PubMed1989

High levels of oral yeasts in early HIV-1 infection.

Ten human immunodeficiency virus-1 (HIV-1) infected homosexual or bisexual individuals (ages 24-45) with no history of opportunistic infection were examined, by culture, for the presence of yeasts in whole saliva and on oral mucosa. All were HIV-1 antibody-positive men, non-smokers, non-denture wearers, and taking no medication. The mean salivary level of yeast was four logs higher in the HIV-1 infected group compared to a control group of normal, unmedicated, non-smoking men (ages 20-41) who denied any risk behavior for HIV-1 infection. Identification of the yeast in these HIV-1 positive individuals established that Candida albicans was the predominant species found in whole saliva and on buccal mucosa and tongue. Distinct hyphae were observed with only one mucosal sample. No significant correlation was found between whole saliva yeast concentration and the T4/T8 lymphocyte ratios or absolute number of T4 cells. No correlation was observed between oral yeast concentration and anti-C. albicans IgA titers. The high level of oral yeast in these individuals prior to the development of opportunistic infections is consistent with the suggestion that oral defense mechanisms are compromised in individuals following HIV-1 infection.

Adult↗
PubMed1989

Salivary inhibition of HIV-1 infectivity: functional properties and distribution in men, women, and children.

Human salivary gland secretions inhibit infection of human lymphocytes by the human immunodeficiency virus 1 (HIV-1), the causative agent of the acquired immune deficiency syndrome (AIDS). This activity was found in saliva collected directly from the orifice of the major salivary gland ducts and the whole saliva of healthy male volunteers. In the current report, the observations on salivary secretions are expanded to a greater number of individuals, including healthy women and children, and men infected with HIV-1.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Beta-adrenergic regulation of c-fos gene expression in an epithelial cell line.

Stimulation of beta-adrenoreceptors in the RSMT-A5 epithelial cell line is accompanied by an early and transient increase in the expression of the proto-oncogene c-fos. Maximal induction was at 30 min, returning to basal levels after 2 h. Similar results were obtained when cells were incubated with 8-bromo-cAMP. The induction of c-fos is specific since the expression of p53, a transformation-related gene, is not modulated by isoproterenol or 8-bromo-cAMP. The increase in c-fos gene expression is not associated with proliferative activity in these epithelial cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1988

Oral defense mechanisms are impaired early in HIV-1 infected patients.

We have examined the hypothesis that individuals infected with human immune deficiency virus type 1 (HIV-1) experience significant, specific alterations in mechanisms protecting the oral cavity prior to the appearance of AIDS-related systemic opportunistic infections. In a study of 13 early-stage, stable anti-HIV antibody positive patients, parotid salivary function was found to be generally intact. In contrast, several indicators of submandibular gland dysfunction were detected. In particular, stimulated fluid output was decreased and salivary lysozyme levels were increased relative to controls by 50-60% for both resting (p less than 0.05) and stimulated (p less than 0.001) conditions. Also, the frequency of albumin detection in submandibular saliva samples was approximately 65% in HIV-1 infected patients vs. 0% in controls (p less than 0.05). In addition, cytologic evaluation of oral mucosa revealed a fivefold increase in the prevalence of candidal hyphae in HIV-1 infected patients compared to controls (41% vs. 8%, p less than 0.05). We conclude that normal oral defense mechanisms show signs of compromise in HIV-1 infected individuals. We suggest that (a) effects of HIV-1 infection are seen early in the oral cavity, (b) impairment of oral defense mechanisms may facilitate entry of microorganisms with an attendant increased risk of morbidity and mortality, and (c) intensive oral surveillance and prophylactic care should be part of the routine management afforded to AIDS patients soon after HIV-1 infection is recognized.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Microtubule disruption enhances prostaglandin E2 production in osteoblastic cells.

Prostaglandins have been implicated in the response of bone to mechanical stimuli. To explore the potential role of the cytoskeleton in the control of prostaglandin production, we examined the effect of cytoskeleton disrupting agents on arachidonic acid metabolism in rat calvaria osteoblastic cells. We found that microtubule disrupting agents increase prostaglandin E production 4-5-fold. Stimulation was first detectable at 4 h and rose sharply between 4 and 8 h. 2 h exposure to 1 microM colchicine was sufficient to produce the maximum effect. Cytochalasin B at concentrations which caused marked shape changes had no effect on prostaglandin E production or on its stimulation by colchicine. Taxol, a stabilizer of microtubules, reduced the colchicine effect. The increase in prostaglandin E production was associated with enhanced conversion of arachidonic acid to prostaglandin E2 rather than enhanced release of arachidonic acid from phospholipids. This increase in enzymatic activity was not abolished by cycloheximide treatment at concentrations which inhibited 90% of protein synthesis in the cells.

Alkaloids↗
PubMed1984

Tensile forces enhance prostaglandin E synthesis in osteoblastic cells grown on collagen ribbons.

An experimental system has been developed to examine the prostaglandin (PG) production induced by tensile mechanical forces in bone cells cultured on collagen ribbons. Fetal rat calvaria cells (osteoblast-enriched) were grown on collagen ribbons. The collagen ribbons were stretched under culture conditions in a machine that recorded force and displacement. Repeated stretching of the collagen ribbons (8 times, 5-10%, over 2 hours) increased the rate of prostaglandin synthesis approximately 3.5-fold over that of cells on nonstretched ribbons. This system should provide a suitable method to quantitatively study the effect of mechanical forces on various parameters of PG synthesis.

Animals↗