scholarly journals Proteoglycan and glycosaminoglycan synthesis in embryonic mouse salivary glands: effects of beta-D-xyloside, an inhibitor of branching morphogenesis.

1983 ◽  
Vol 96 (5) ◽  
pp. 1443-1450 ◽  
Author(s):  
H A Thompson ◽  
B S Spooner
Keyword(s):  
Salivary Glands ◽  
Dermatan Sulfate ◽  
Branching Morphogenesis ◽  
Proteoglycan Synthesis ◽  
Embryonic Mouse ◽  
Glycosaminoglycan Synthesis ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent ◽  
Stimulation Of

The proteoglycans and glycosaminoglycans synthesized by embryonic mouse salivary glands during normal morphogenesis and in the presence of beta-xyloside, an inhibitor of branching morphogenesis, have been partially characterized. Control and rho-nitrophenyl-beta-D-xyloside-treated salivary rudiments synthesize proteoglycans that are qualitatively similar, based on mobility on Sepharose CL-4B under dissociative conditions and glycosaminoglycan composition. However, beta-xyloside inhibits total proteoglycan-associated glycosaminoglycan synthesis by 50%, and also stimulates synthesis of large amounts of free chondroitin (dermatan) sulfate. This free glycosaminoglycan accounts for the threefold stimulation of total glycosaminoglycan synthesis in beta-xyloside-treated cultures. Several observations suggest that the disruption of proteoglycan synthesis rather than the presence of large amounts of free glycosaminoglycan is responsible for the inhibition of branching morphogenesis. (a) We have been unable to inhibit branching activity by adding large amounts of chondroitin (dermatan) sulfate, extracted from beta-xyloside-treated cultures, to the medium of salivary rudiments undergoing morphogenesis. (b) In the range of 0.1-0.4 mM beta-xyloside, the dose-dependent inhibition of branching morphogenesis is directly correlated with the inhibition of proteoglycan synthesis. The stimulation of free glycosaminoglycan synthesis is independent of dose in this range, since stimulation is maximal even at the lowest concentration used, 0.1 mM. The data strongly suggest that the inhibition of branching morphogenesis is caused by the disruption of proteoglycan synthesis in beta-xyloside-treated salivary glands.

Pentoxifylline inhibits the proliferation and glycosaminoglycan synthesis of cultured fibroblasts derived from patients with Graves' ophthalmopathy and pretibial myxoedema

1993 ◽  
Vol 129 (4) ◽  
pp. 322-327 ◽  
Author(s):  
Chih-Cheng Chang ◽  
Tien-Chun Chang ◽  
Shine CS Kao ◽  
Yea-Fhey Kuo ◽  
Li-Fei Chien
Keyword(s):  
Extraocular Muscles ◽  
Cultured Fibroblasts ◽  
Glycosaminoglycan Synthesis ◽  
Fibroblast Cultures ◽  
Graves Ophthalmopathy ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Presence And Absence ◽  
Dose Dependent ◽  
Pretibial Myxoedema

Excessive amounts of glycosaminoglycans accumulate in the extraocular muscles of patients with Graves' ophthalmopathy and in the affected skin of patients with pretibial myxoedema. It is widely accepted that fibroblasts are the sources of glycosaminoglycan synthesis. Pentoxifylline, an analogue of the methylxanthine theobromine, inhibits the proliferation and certain biosynthetic activities of fibroblasts derived from normal human skin and from skin of patients with some fibrotic disorders. Our objective was to determine whether pentoxifylline has similar effects on fibroblasts derived from patients with Graves' ophthalmopathy and pretibial myxoedema and could serve as a candidate for the treatment of these manifestations. Fibroblasts from the extraocular muscles of two patients with Graves' ophthalmopathy and normal extraocular muscles of two subjects with strabismus, as well as the affected skin of two patients with pretibial myxoedema were cultured in vitro in the presence and absence of pentoxifylline to assay its effect on the proliferation of fibroblasts and their production of glycosaminoglycans. In subconfluent fibroblast cultures, pentoxifylline treatment caused a dose-dependent inhibition of serum-driven fibroblast proliferation. In confluent fibroblast cultures both in the presence and absence of serum, exposure to pentoxifylline similarly resulted in a dose-dependent inhibition of glycosaminoglycan synthesis for all these different kinds of fibroblasts. These findings may form the rationale for a clinical trial using pentoxifylline for the treatment of Graves' ophthalmopathy and pretibial myxoedema.

Russell's viper venom stimulates insulin secretion from rat islets of Langerhans

1993 ◽  
Vol 136 (1) ◽  
pp. 27-33 ◽  
Author(s):  
P. M. Jones ◽  
F. M. Mann
Keyword(s):  
Insulin Secretion ◽  
Islets Of Langerhans ◽  
Prolonged Exposure ◽  
Blue Dye ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Russell’S Viper ◽  
Rat Islets Of Langerhans ◽  
Dose Dependent ◽  
Stimulation Of

ABSTRACT Burmese Russell's viper venom (RVV) caused a dose-and temperature-dependent stimulation of insulin secretion from islets of Langerhans isolated from rat pancreas by collagenase digestion. RVV stimulated both basal and glucose-induced insulin secretion at concentrations which did not compromise islet cell viability as assessed by exclusion of trypan blue dye. The effects of RVV on insulin secretion could not be attributed to the activation of protein kinase C (PKC), since down-regulation of PKC by prolonged exposure to a tumour-promoting phorbol ester did not abolish subsequent secretory responses to RVV. However, RVV-induced insulin secretion was inhibited in the absence of extracellular Ca2 +, and RVV did not stimulate insulin secretion from Ca2+-clamped electrically permeabilized islets at either substimulatory (50 nmol/l) or stimulatory (10 μmol/l) concentrations of Ca2 +, suggesting that changes in cytosolic Ca2+ are important in the stimulation of insulin secretion by RVV. The phospholipase A2 (PLA2) inhibitor quinacrine caused a dose-dependent inhibition of RVV-induced insulin secretion, suggesting that the activation of PLA2, perhaps in response to Ca2+ influx, may be partially responsible for RVV-induced insulin secretion. Journal of Endocrinology (1993) 136, 27–33

scholarly journals The role of GTP in prostaglandin E1 stimulation of adenylate cyclase in platelet membranes

1983 ◽  
Vol 214 (1) ◽  
pp. 231-234 ◽  
Author(s):  
J M Stein ◽  
B R Martin
Keyword(s):  
Adenylate Cyclase ◽  
Prostaglandin E1 ◽  
Platelet Membrane ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent ◽  
Stimulation Of

Adenylate cyclase activity in platelet membrane preparations was measured in the presence of prostaglandin E1 (PGE1), GTP and a non-hydrolysable analogue of GDP, guanosine 5′-[beta-thio]diphosphate (GDP[beta S]). A dose-dependent inhibition of adenylate cyclase by GDP[beta S] was observed that could be reversed either by adding increased amounts of GTP or of PGE1.

scholarly journals Uncoupling of chondroitin sulfate glycosaminoglycan synthesis by brefeldin A.

1991 ◽  
Vol 115 (5) ◽  
pp. 1463-1473 ◽  
Author(s):  
R C Spiro ◽  
H H Freeze ◽  
D Sampath ◽  
J A Garcia
Keyword(s):  
Chondroitin Sulfate ◽  
Functional Organization ◽  
Core Protein ◽  
Brefeldin A ◽  
Glycosaminoglycan Synthesis ◽  
Core Proteins ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Golgi Network ◽  
Dose Dependent

Brefeldin A has dramatic, well-documented, effects on the structural and functional organization of the Golgi complex. We have examined the effects of brefeldin A (BFA) on the Golgi-localized synthesis and addition of chondroitin sulfate glycosaminoglycan carbohydrate side chains. BFA caused a dose-dependent inhibition of chondroitin sulfate glycosaminoglycan elongation and sulfation onto the core proteins of the melanoma-associated proteoglycan and the major histocompatibility complex class II-associated invariant chain. In the presence of BFA, the melanoma proteoglycan core protein was retained in the ER but still acquired complex, sialylated, N-linked oligosaccharides, as measured by digestion with endoglycosidase H and neuraminidase. The initiation of glycosaminoglycan synthesis was not affected by BFA, as shown by the incorporation of [6-3H]galactose into a protein-carbohydrate linkage region that was sensitive to beta-elimination. The ability of cells to use an exogenous acceptor, p-nitrophenyl-beta-D-xyloside, to elongate and sulfate core protein-free glycosaminoglycans, was completely inhibited by BFA. The effects of BFA were completely reversible in the absence of new protein synthesis. These experiments indicate that BFA effectively uncouples chondroitin sulfate glycosaminoglycan synthesis by segregating initiation reactions from elongation and sulfation events. Our findings support the proposal that glycosaminoglycan elongation and sulfation reactions are associated with the trans-Golgi network, a BFA-resistant, Golgi subcompartment.

Effects of colchicine and vinblastine on in vitro gastric secretion.

1979 ◽  
Vol 236 (5) ◽  
pp. E550
Author(s):  
D K Kasbekar ◽  
G S Gordon
Keyword(s):  
Gastric Secretion ◽  
Cytochalasin B ◽  
Pepsinogen Secretion ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Kinetics Of ◽  
Dose Dependent ◽  
Kinetics Of Inhibition ◽  
Stimulation Of

The effects of colchicine and vinblastine on in vitro bullfrog gastric mucosal preparations were studied with respect to H+ and pepsinogen secretion. In the concentration range of 1--50 mM, an initial but transient colchicine-mediated stimulation of H+ secretion is followed by a dose-dependent inhibition. The transient stimulation of H+ secretion can be confirmed in resting preparations in the absence of added secretagogues. In the same concentration range, colchicine inhibits pepsinogen secretion to a greater degree than H+ secretion. Vinblastine (10(-5)--5 X 10(-4) M) was more effective than colchicine in inhibiting both H+ and pepsinogen secretion. The kinetics of inhibition of secretion by both colchicine and vinblastine were slow. Cytochalasin B had no effect on either secretion.

Gastrin and somatostatin secretion by perfused rat stomach: functional linkage of antral peptides

1980 ◽  
Vol 238 (6) ◽  
pp. G495-G501 ◽  
Author(s):  
B. Saffouri ◽  
G. C. Weir ◽  
K. N. Bitar ◽  
G. M. Makhlouf
Keyword(s):  
Inverse Relationship ◽  
Rat Stomach ◽  
Gastrin Secretion ◽  
Functional Linkage ◽  
Somatostatin Secretion ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Stimulation Of

The isolated vascularly perfused rat stomach was used to study the polarity, kinetics, and stoichiometry of gastrin and somatostatin secretion and the interaction of the two antral peptides. The secretion of gastrin (79%) and somatostatin (95%) was predominantly in the circulation. Methacholine (5 x 10(-8) to 5 x 10(-4) M) produced a biphasic dose-dependent increase in gastrin secretion. The maximal gastrin response (434 +/- 89% above basal levels; P less than 0.001) was partially inhibited by 10(-8) M atropine and completely inhibited by 10(-7) M atropine. Methacholine produced a dose-dependent inhibition of somatostatin secretion; the inhibition was blocked by atropine. An inverse relationship between the secretion of gastrin and somatostatin was noted in the basal state and during infusion of methacholine or prostaglandin E2; the latter had effects on gastrin and somatostatin secretion opposite to those of methacholine. The data, together with data reported elsewhere that somatostatin antiserum stimulates gastrin secretion in the perfused stomach, are consistent with the hypothesis that gastric somatostatin secretion exerts a continuous restraint on basal gastrin secretion and that stimulation of gastrin secretion may be mediated in part by inhibition of somatostatin secretion.

scholarly journals CXCL9 and CXCL11 Chemokines Modulation by Peroxisome Proliferator-Activated Receptor-α Agonists Secretion in Graves’ and Normal Thyrocytes

2010 ◽  
Vol 95 (12) ◽  
pp. E413-E420 ◽  
Author(s):  
Alessandro Antonelli ◽  
Silvia Martina Ferrari ◽  
Silvia Frascerra ◽  
Cinzia Pupilli ◽  
Caterina Mancusi ◽  
...  
Keyword(s):  
Peroxisome Proliferator ◽  
Thyroid Cells ◽  
Peroxisome Proliferator Activated Receptor ◽  
Dependent Inhibition ◽  
Pparγ Agonists ◽  
Dose Dependent Inhibition ◽  
And Control ◽  
Dose Dependent ◽  
Stimulation Of

Context: Peroxisome proliferator-activated receptor (PPAR)-α has been shown to exert immunomodulatory effects in autoimmune disorders. However, until now, no data were present in the literature about the effect of PPARα activation on CXCL9 and CXCL11 chemokines in general or on secretion of these chemokines in thyroid cells. Objective and Design: The presence of PPARα and PPARγ has been evaluated by real-time-PCR in Graves’ disease (GD) and control cells in primary culture. Furthermore, we have tested the role of PPARα and PPARγ activation on CXCL9 and CXCL11 secretion in GD and control cells after stimulation of these chemokines secretion with IFNγ and TNFα. Results: This study shows the presence of PPARα and PPARγ in GD and control cells. A potent dose-dependent inhibition by PPARα-agonists was observed on the cytokines-stimulated secretion of CXCL9 and CXCL11 in GD and control cells. The potency of the PPARα agonists used was maximum on the secretion of CXCL9, reaching about 90% of inhibition by fenofibrate and 85% by ciprofibrate. The relative potency of the compounds was different with each chemokine; for example, gemfibrozil exerted a 55% inhibition on CXCL11, whereas it had a weaker activity on CXCL9 (40% inhibition). PPARα agonists were stronger (ANOVA, P < 0.001) inhibitors of CXCL9 and CXCL11 secretion in thyrocytes than PPARγ agonists. Conclusions: Our study shows the presence of PPARα in GD and control thyrocytes. PPARα activators are potent inhibitors of the secretion of CXCL9 and CXCL11, suggesting that PPARα may be involved in the modulation of the immune response in the thyroid.

Differences between antigenic determinants of pig and cat zona pellucida proteins

Reproduction ◽  
2000 ◽  
pp. 15-23 ◽  
Author(s):  
K Jewgenow ◽  
M Rohleder ◽  
I Wegner
Keyword(s):  
In Vitro Fertilization ◽  
Zona Pellucida ◽  
Antigenic Determinants ◽  
Vitro Fertilization ◽  
Contraceptive Vaccine ◽  
Sperm Binding ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

Despite many efforts, the control of reproduction in feral cat populations is still a problem in urban regions around the world. Immunocontraception is a promising approach; thus the present study examined the suitability of the widely used pig zona pellucida proteins (pZP) for contraception in feral domestic cats. Purified zona pellucida proteins obtained from pig and cat ovaries were used to produce highly specific antisera in rabbits. Antibodies against pZP raised in rabbits or lions were not effective inhibitors of either in vitro sperm binding (cat spermatozoa to cat oocytes) or in vitro fertilization in cats, whereas antibodies against feline zona pellucida proteins (fZP) raised in rabbits showed a dose-dependent inhibition of in vitro fertilization. Immunoelectrophoresis, ELISA and immunohistology of ovaries confirmed these results, showing crossreactivity of anti-fZP sera to fZP and to a lesser extent to pZP, but no interaction of anti-pZP sera with fZP. It is concluded that cat and pig zonae pellucidae express a very small number of shared antigenic determinants, making the use of pZP vaccine in cats questionable. A contraceptive vaccine based on feline zona pellucida determinants will be a better choice for the control of reproduction in feral cats if immunogenity can be achieved.

Antioxidant effects and in vitro cytotoxicity on human cancer cell lines of flavonoid-rich Flamboyant (Delonix regia (Bojer) Raf.) flower extract

2020 ◽  
Vol 21 ◽  
Author(s):  
Putthiporn Khongkaew ◽  
Phanphen Wattanaarsakit ◽  
Konstantinos I. Papadopoulos ◽  
Watcharaphong Chaemsawang
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Cancer Cell ◽  
Leukemia Cell ◽  
Leukemia Cell Line ◽  
Flower Extract ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Murine Leukemia Cell ◽  
Dose Dependent

Background: Cancer is a noncommunicable disease with increasing incidence and mortality rates both worldwide and in Thailand. Its apparent lack of effective treatments is posing challenging public health issues. Introduction: Encouraging research results indicating probable anti-cancer properties of the Delonix regia flower extract (DRE) have prompted us to evaluate the feasibility of developing a type of product for future cancer prevention or treatment. Methods and Results: In the present report, using High Performance Liquid Chromatography (HPLC), we demonstrate in the DRE, the presence of high concentrations of three identifiable flavonoids, namely rutin 4.15±0.30 % w/w, isoquercitrin 3.04±0.02 %w/w, and myricetin 2.61±0.01 % w/w respectively while the IC50 of DPPH and ABTS assay antioxidation activity was 66.88±6.30 µg/ml and 53.65±7.24 µg/ml respectively. Discussion: Our cancer cell line studies using the MTT assay demonstrated DREs potent and dose dependent inhibition of murine leukemia cell line (P-388: 35.28±4.07% of cell viability remaining), as well as of human breast adenocarcinoma (MCF-7), human cervical carcinoma (HeLa), human oral cavity carcinoma (KB), and human colon carcinoma (HT-29) cell lines in that order of magnitude. Conclusion: Three identifiable flavonoids (rutin, isoquercitrin and myricetin) with high antioxidation activity and potent and dose dependent inhibition of murine leukemia cell line and five other cancer cell lines were documented in the DRE. The extract’s lack of cytotoxicity in 3 normal cell lines is a rare advantage not usually seen in current antineoplastic agents. Yet another challenge of the DRE was its low dissolution rate and long-term storage stability, issues to be resolved before a future product can be formulated.

Investigation on the antibacterial activity of electronic cigarette liquids (ECLs): a proof of concept study

2020 ◽  
Vol 21 ◽  
Author(s):  
Virginia Fuochi ◽  
Massimo Caruso ◽  
Rosalia Emma ◽  
Aldo Stivala ◽  
Riccardo Polosa ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Bacterial Species ◽  
A549 Cells ◽  
Bactericidal Effect ◽  
Minimal Bactericidal Concentration ◽  
Viability Assay ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

Background: The key ingredients of e-cigarettes liquid are commonly propane-1,2-diol (also called propylene glycol) and propane-1,2,3-triol (vegetal glycerol) and their antimicrobial effects are already established. The nicotine and flavors which are often present in e-liquids can interfere with the growth of some microorganisms. Objective: The effect of the combining these elements in e-liquids is unknown. The aim of the study was to investigate the possible effects of these liquids on bacterial growth in the presence or absence of nicotine and flavors. Methods: Susceptibilities of pathogenic strains (Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis and Sarcina lutea) were studied by means of a multidisciplinary approach. Cell viability and antioxidant assays were also evaluated. Results: All e-liquids investigated showed antibacterial activity against at least one pathogenic strain. A higher activity was correlated to the presence of flavors and nicotine. Discussion: In most cases the value of minimal bactericidal concentration is equal to the value of minimal inhibitory concentration showing that these substances have a bactericidal effect. This effect was observed in concentrations up to 6.25% v/v. Antioxidant activity was also correlated to presence of flavors. Over time, the viability assay in human epithelial lung A549 cells showed a dose-dependent inhibition of cell growth. Conclusion: Our results have shown that flavors considerably enhance the antibacterial activity of propane-1,2-diol and propane-1,2,3-triol. This study provides important evidence that should be taken into consideration in further investigative approaches, to clarify the different sensitivity of the various bacterial species to e-liquids, including the respiratory microbiota, to highlight the possible role of flavors and nicotine.

Sign in / Sign up

Export Citation Format

Share Document