scholarly journals Insulin-responsive cultured foetal-rat hepatocytes. Their preparation and characterization

1984 ◽  
Vol 223 (1) ◽  
pp. 39-46 ◽  
Author(s):  
D C DeSante ◽  
L Little ◽  
D E Peavy ◽  
F Vinicor
Keyword(s):  
Monolayer Culture ◽  
Cultured Cells ◽  
Rat Hepatocytes ◽  
Dependent Manner ◽  
Deoxyribonuclease I ◽  
Haematopoietic Cells ◽  
Foetal Rat ◽  
The Relationship ◽  
Dose Dependent ◽  
Scatchard Plots

An improved non-perfusion method for the preparation of cultured foetal-rat hepatocytes is described. Digestion of the liver with collagenase and deoxyribonuclease I gave yields of 40 × 10(6) hepatocytes/g of liver. The plating efficiency of hepatocytes in medium with 10 microM-cortisol was 50%. Cell morphology and metabolism were maintained through 3 days of monolayer culture, with minimal contamination by haematopoietic cells or fibroblasts. The cultured cells bound and degraded 125I-insulin in a time- and dose-dependent manner. The estimated ED50 for competitive binding at 37 degrees C was 1.1 nM. Curvilinear Scatchard plots were observed, with estimates of 16 500 high-affinity sites (Kd = 813 pM) and 53 000 low-affinity sites (Kd = 23 nM) per cell. The cultured cells demonstrated a glycogenic response to insulin, with an estimated ED50 of 120 pM. The degree of glycogenic response to insulin varied with time in culture: 500% above basal on day 1, 200% on day 2, and only 150% on day 3. Cultured foetal cells also exhibited a time-dependent uptake of 2-aminoisobutyric acid, which, in contrast with previous reports with adult cells, was not stimulated by the presence of 10 nM-insulin. Cultured foetal hepatocytes may provide an interesting model with which to study the relationship between insulin-receptor binding and insulin action.

scholarly journals Kahweol Exerts Skin Moisturizing Activities by Upregulating STAT1 Activity

2021 ◽  
Vol 22 (16) ◽  
pp. 8864
Author(s):  
Hongxi Chen ◽  
Mohammad Amjad Hossain ◽  
Jong-Hoon Kim ◽  
Jae Youl Cho
Keyword(s):  
Proper Time ◽  
Radical Scavenging ◽  
Polymerase Chain Reaction Analysis ◽  
Luciferase Assay ◽  
Dependent Manner ◽  
Diphenyltetrazolium Bromide ◽  
Polymerase Chain ◽  
Radical Scavenging Ability ◽  
The Relationship ◽  
Dose Dependent

Kahweol is a diterpene present in coffee. Until now, several studies have shown that kahweol has anti-inflammatory and anti-angiogenic functions. Due to the limited research available about skin protection, this study aims to discern the potential abilities of kahweol and the possible regulation targets. First, the cytotoxicity of kahweol was checked by 3-4-5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide assay, while 2,20-azino-bis (3ethylbenzothiazoline-6-sulphonic acid) diammonium salt and 1-diphenyl-2-picryl-hydrazyl were used to examine the radical scavenging ability. Polymerase chain reaction analysis was performed to explore the proper time points and doses affecting skin hydration and barrier-related genes. Luciferase assay and Western blotting were used to explore the possible transcription factors. Finally, fludarabine (a STAT1 inhibitor) was chosen to discern the relationship between skin-moisturizing factors and STAT1. We found that HaCaT cells experienced no toxicity from kahweol, and kahweol displayed moderate radical scavenging ability. Moreover, kahweol increased the outcome of HAS1, HAS2, occludin, and TGM-1 from six hours in a dose-dependent manner as well as the activation of STAT1 from six hours. Additionally, kahweol recovered the suppression of HAS2, STAT1-mediated luciferase activity, and HA secretion, which was all downregulated by fludarabine. In this study, we demonstrated that kahweol promotes skin-moisturizing activities by upregulating STAT1.

Tolbutamide inhibits glucagon-induced phosphorylation of 6PF-2-K/Fru-2,6-P2ase in rat hepatocytes

1995 ◽  
Vol 268 (3) ◽  
pp. E391-E396
Author(s):  
H. Ayame ◽  
A. Matsutani ◽  
H. Inoue ◽  
T. Kaneko ◽  
K. Kaku
Keyword(s):  
Rat Hepatocytes ◽  
Bifunctional Enzyme ◽  
Dependent Manner ◽  
Enzyme Protein ◽  
Dependent Protein ◽  
Sulfonylurea Drugs ◽  
Dose Dependent ◽  
Increased Activity ◽  
Reduced Activity

In previous studies, we demonstrated that tolbutamide inhibits a phosphorylation of hepatic 6-phosphofructo-2-kinase (6PF-2-K)/fructose-2,6-bisphosphatase (Fru-2,6-P2ase) catalyzed by the adenosine 3',5'-cyclic monophosphate-dependent protein kinase in a reconstruction system using the purified enzyme from the rat liver. In the current study, to assess a role of tolbutamide on hepatic 6PF-2-K/Fru-2,6-P2ase physiologically, we used intact rat hepatocytes and examined effects of tolbutamide on a phosphorylation of the bifunctional enzyme in the presence of glucagon. Glucagon induced a rapid phosphorylation of hepatic 6PF-2-K/Fru-2,6-P2ase accompanied by an inhibition of 6PF-2-K activity and a stimulation of Fru-2,6-P2ase activity in a dose-dependent manner. Tolbutamide inhibited glucagon-induced phosphorylation of the bifunctional enzyme protein in a dose-dependent manner. By adding 2 mM tolbutamide, reduced activity of 6PF-2-K and increased activity of Fru-2,6-P2ase in the presence of 10(-9) M glucagon were partially restored. The present results suggest the possibility that tolbutamide modulates the activity of hepatic 6PF-2-K/Fru-2,6-P2ase through inhibiting a phosphorylation of the enzyme protein. The counterregulatory influence of tolbutamide on the effect of glucagon suggests a possible mechanism for the extrapancreatic effect of sulfonylurea drugs.

scholarly journals Effects of Caffeoylquinic Acid Derivatives and C-Flavonoid from Lychnophora ericoides on in vitro Inflammatory Mediator Production

2010 ◽  
Vol 5 (5) ◽  
pp. 1934578X1000500 ◽  
Author(s):  
Michel David dos Santos ◽  
Guanjie Chen ◽  
Maria Camila Almeida ◽  
Denis Melo Soares ◽  
Glória Emília Petto de Souza ◽  
...  
Keyword(s):  
Inflammatory Mediators ◽  
Cultured Cells ◽  
Dependent Manner ◽  
Caffeoylquinic Acid ◽  
Inflammatory Mediator Production ◽  
Dicaffeoylquinic Acid ◽  
Tnf Α ◽  
Dose Dependent Fashion ◽  
Dose Dependent

In this study we aimed at evaluating the effect of the major polar constituents of the medicinal plant Lychnophora ericoides on the production of inflammatory mediators produced by LPS-stimulated U-937 cells. The 6,8-di- C-β-glucosylapigenin (vicenin-2) presented no effect on tumor necrosis factor (TNF)-α production, but inhibited, in a dose-dependent manner, the production of prostaglandin (PG) E2 without altering the expression of cyclooxygenase (COX) -2 protein. 3,5-Dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid, at lower concentrations, had small but significant effects on reducing PGE2 levels; at higher doses these compounds stimulated PGE2 and also TNF-α production by the cells. All the caffeoylquinic acid derivatives, in a dose-dependent fashion, were able to inhibit monocyte chemoattractant protein-3 synthesis/release, with 4,5-DCQ being the most potent at the highest tested concentration. These results add important information on the effects of plant natural polyphenols, namely vicenin-2 and caffeoylquinic acid derivatives, on the production of inflammatory mediators by cultured cells.

scholarly journals Peptidic degron for IMiD-induced degradation of heterologous proteins

2019 ◽  
Vol 116 (7) ◽  
pp. 2539-2544 ◽  
Author(s):  
Vidyasagar Koduri ◽  
Samuel K. McBrayer ◽  
Ella Liberzon ◽  
Adam C. Wang ◽  
Kimberly J. Briggs ◽  
...  
Keyword(s):  
Protein Function ◽  
Cultured Cells ◽  
Ex Vivo ◽  
Ease Of Use ◽  
Dependent Manner ◽  
Heterologous Proteins ◽  
Ubiquitin Ligase Complex ◽  
Dose Dependent ◽  
Current Systems

Current systems for modulating the abundance of proteins of interest in living cells are powerful tools for studying protein function but differ in terms of their complexity and ease of use. Moreover, no one system is ideal for all applications, and the best system for a given protein of interest must often be determined empirically. The thalidomide-like molecules (collectively called the IMiDs) bind to the ubiquitously expressed cereblon ubiquitin ligase complex and alter its substrate specificity such that it targets the IKZF1 and IKZF3 lymphocyte transcription factors for destruction. Here, we mapped the minimal IMiD-responsive IKZF3 degron and show that this peptidic degron can be used to target heterologous proteins for destruction with IMiDs in a time- and dose-dependent manner in cultured cells grown ex vivo or in vivo.

Cutaneous Adverse Effects With HER1/EGFR-Targeted Agents: Is There a Silver Lining?

2005 ◽  
Vol 23 (22) ◽  
pp. 5235-5246 ◽  
Author(s):  
Román Peréz-Soler ◽  
Leonard Saltz
Keyword(s):  
Surrogate Marker ◽  
Growth Factor Receptor ◽  
Dependent Manner ◽  
Activity Data ◽  
Egfr Inhibition ◽  
The Face ◽  
Epidermal Growth ◽  
Management Recommendations ◽  
The Relationship ◽  
Dose Dependent

The human epidermal growth factor receptor (HER1/EGFR) is dysregulated in many solid tumors, making it an attractive target for anticancer therapy. A number of agents that target this receptor are in use or in development. A specific adverse effect common to this class of agent is a papulopustular rash, usually on the face and upper torso, which generally occurs in a dose-dependent manner. Little is known about the etiology of this rash, and there are no clear evidence-based management recommendations. Histologic data indicate that rash may be caused by HER1/EGFR inhibition in skin, although this has not been confirmed. Findings suggest that there is a relationship between the development of rash and response and/or survival, making rash a potential surrogate marker of activity. Data from multiple studies with cetuximab and erlotinib show a consistent relationship between rash and response, as well as between rash and survival. The relationship between rash and clinical outcome is currently less consistent for gefitinib. Some studies report a correlation, whereas others do not. The cause of the possible relationship between rash and clinical benefit remains unclear at this time, and additional studies are needed to determine the clinical utility of this observation.

scholarly journals Calcium rather than cyclic AMP is an intracellular messenger of parathyroid hormone action on glycogen metabolism in isolated rat hepatocytes

1989 ◽  
Vol 258 (3) ◽  
pp. 889-894 ◽  
Author(s):  
T Mine ◽  
I Kojima ◽  
E Ogata
Keyword(s):  
Parathyroid Hormone ◽  
Cyclic Amp ◽  
Glucose Production ◽  
Rat Hepatocytes ◽  
Free Calcium ◽  
Dependent Manner ◽  
Isolated Rat Hepatocytes ◽  
Glucose Output ◽  
Dose Dependent ◽  
Isolated Rat

The synthetic 1-34 fragment of human parathyroid hormone (1-34hPTH) stimulated glucose production in isolated rat hepatocytes. The effect of 1-34hPTH was dose-dependent and 10(10) M-1-34 hPTH elicited the maximum glucose output, which was approx. 80% of that by glucagon. Although 1-34hPTH induced a small increase in cyclic AMP production at concentrations higher than 10(-9) M, 10(-10) M-1-34hPTH induced the maximum glucose output without significant elevation of cyclic AMP. This is in contrast to the action of forskolin, which increased glucose output to the same extent as 10(-10) M-1-34hPTH by causing a 2-fold elevation of cyclic AMP. In addition to increasing cyclic AMP, 1-34hPTH caused an increase in cytoplasmic free calcium concentration ([Ca2+]c). When the effect of 1-34hPTH on [Ca2+]c was studied in aequorin-loaded cells, low concentrations of 1-34hPTH increased [Ca2+]c: the 1-34hPTH effect on [Ca2+]c was detected at as low as 10(-12) M and increased in a dose-dependent manner. 1-34hPTH increased [Ca2+]c even in the presence of 1 microM extracellular calcium, suggesting that PTH mobilizes calcium from an intracellular pool. In line with these observations, 1-34hPTH increased the production of inositol trisphosphate. These results suggest that: (1) PTH activates both cyclic AMP and calcium messenger systems and (2) PTH stimulates glycogenolysis mainly via the calcium messenger system.

scholarly journals Cross-talk between glucagon- and adenosine-mediated signalling systems in rat hepatocytes: effects on cyclic AMP-phosphodiesterase activity

1995 ◽  
Vol 312 (3) ◽  
pp. 763-767 ◽  
Author(s):  
M Robles-Flores ◽  
G Allende ◽  
E Piña ◽  
J A García-Sáinz
Keyword(s):  
Cyclic Amp ◽  
Pertussis Toxin ◽  
Plasma Membranes ◽  
Rat Hepatocytes ◽  
Dependent Manner ◽  
Phosphodiesterase Activity ◽  
Cyclic Amp Phosphodiesterase ◽  
Cyclic Amp Accumulation ◽  
A1 Adenosine Receptors ◽  
Dose Dependent

The effect of adenosine analogues on glucagon-stimulated cyclic AMP accumulation in rat hepatocytes was explored. N6-Cyclopentyladenosine (CPA), 5′-N-ethylcarboxamidoadenosine and N6-(R-phenylisopropyl)adenosine inhibited in a dose-dependent manner the cyclic AMP accumulation induced by glucagon. This effect seems to be mediated through A1 adenosine receptors. Pertussis toxin completely abolished the effect of CPA on glucagon-stimulated cyclic AMP accumulation in whole cells which suggested that a pertussis-toxin-sensitive G-protein was involved. On the other hand, this action of adenosine analogues on glucagon-induced cyclic AMP accumulation was reverted by the selective low-Km cyclic AMP-phosphodiesterase inhibitor Ro 20-1724. Analysis of cyclic AMP-phosphodiesterase activity in purified hepatocyte plasma membranes showed that glucagon in the presence of GTP inhibited basal PDE activity by 45% and that CPA reverted this inhibition in dose-dependent manner. In membranes derived from pertussis-toxin-treated rats, we observed no inhibition of cyclic AMP-phosphodiesterase activity by glucagon in the absence or presence of CPA. Our results indicate that in hepatocyte plasma membranes, stimulation of adenylate cyclase activity and inhibition of a low-Km cyclic AMP phosphodiesterase activity are co-ordinately regulated by glucagon, and that A1 adenosine receptors can inhibit glucagon-stimulated cyclic AMP accumulation by blocking glucagon's effect on phosphodiesterase activity.

scholarly journals The Escherichia coli Common Pilus and the Bundle-Forming Pilus Act in Concert during the Formation of Localized Adherence by Enteropathogenic E. coli

2009 ◽  
Vol 191 (11) ◽  
pp. 3451-3461 ◽  
Author(s):  
Zeus Saldaña ◽  
Ayşen L. Erdem ◽  
Stephanie Schüller ◽  
Iruka N. Okeke ◽  
Mark Lucas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Cultured Cells ◽  
Dependent Manner ◽  
Triple Mutant ◽  
E Coli ◽  
Accessory Factor ◽  
Isogenic Mutants ◽  
Dose Dependent ◽  
Background Expression

ABSTRACT Although the bundle-forming pilus (BFP) of enteropathogenic Escherichia coli (EPEC) mediates microcolony formation on epithelial cells, the adherence of BFP-deficient mutants is significantly abrogated, but the mutants are still adherent due to the presence of intimin and possibly other adhesins. In this study we investigated the contribution of the recently described E. coli common pilus (ECP) to the overall adherence properties of EPEC. We found that ECP and BFP structures can be simultaneously observed in the course (between zero time and 7 h during infection) of formation of localized adherence on cultured epithelial cells. These two pilus types colocalized at different levels of the microcolony topology, tethering the adhering bacteria. No evidence of BFP disappearance was found after prolonged infection. When expressed from a plasmid present in nonadherent E. coli HB101, ECP rendered this organism highly adherent at levels comparable to those of HB101 expressing the BFP. Purified ECP bound in a dose-dependent manner to epithelial cells, and the binding was blocked with anti-ECP antibodies, confirming that the pili possess adhesin properties. An ECP mutant showed only a modest reduction in adherence to cultured cells due to background expression levels of BFP and intimin. However, isogenic mutants not expressing EspA or BFP were significantly less adherent when the ecpA gene was also deleted. Furthermore, a ΔespA ΔecpA double mutant (unable to translocate Tir and to establish intimate adhesion) was at least 10-fold less adherent than the ΔespA and ΔecpA single mutants, even in the presence of BFP. A Δbfp ΔespA ΔecpA triple mutant showed the least adherence compared to the wild type and all the isogenic mutant strains tested, suggesting that ECP plays a synergistic role in adherence. Our data indicate that ECP is an accessory factor that, in association with BFP and other adhesins, contributes to the multifactorial complex interaction of EPEC with host epithelial cells.

scholarly journals Prostaglandins E2 and F2α increase fructose 2,6-bisphosphate levels in isolated hepatocytes

1991 ◽  
Vol 274 (1) ◽  
pp. 309-312 ◽  
Author(s):  
A M Gómez-Foix ◽  
J E Rodríguez-Gil ◽  
J J Guinovart ◽  
F Bosch
Keyword(s):  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Glycolytic Flux ◽  
Dependent Manner ◽  
Hepatic Glucose Metabolism ◽  
Prostaglandin F2 Alpha ◽  
Hepatic Glucose ◽  
Dose Dependent ◽  
Prostaglandins E2 And F2α ◽  
Stimulation Of

In hepatocytes isolated from fed rats, prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) increased, in a time- and dose-dependent manner, fructose 2,6-bisphosphate [Fru(2,6)P2] levels and stimulated the glycolytic flux. The rise in Fru(2,6)P2 was related to an increase in glucose 6-phosphate levels which resulted from the stimulation of glycogenolysis. In cells obtained from 24 h-starved rats, no effects of either PGE2 or PGF2 alpha could be observed. In addition, when the stimulation of glycogenolysis was abolished by incubation of fed-rat hepatocytes in a Ca2(+)-depleted medium, Fru(2,6)P2 levels did not increase. Furthermore, no effects of PGs on 6-phosphofructo-2-kinase activity could be observed. These results indicate that PGE2 and PGF2 alpha show similar actions to Ca2(+)-dependent hormones on hepatic glucose metabolism.

scholarly journals Nitrous oxide causes peripheral neuropathy in a dose dependent manner among recreational users

2019 ◽  
Vol 34 (2) ◽  
pp. 229-236 ◽  
Author(s):  
Adam R Winstock ◽  
Jason A Ferris
Keyword(s):  
Nitrous Oxide ◽  
Peripheral Neuropathy ◽  
Dependent Manner ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Gender And Age ◽  
And Gender ◽  
Not At Risk ◽  
The Relationship ◽  
Dose Dependent

Background: Nitrous oxide (N2O) has been used in clinical and recreational settings for over 150 years. Through inactivation of the Vitamin B12 dependent enzyme, methionine synthase, N2O can lead to the development of peripheral neuropathy. This study sought to determine the relationship between the exposure and risk of neurological symptoms in the largest ever sample of users. Design: Data are drawn from the Global Drug Survey (GDS) over three consecutive years (2014–2016). The Global Drug Survey is an online, cross-sectional survey of substance use, translated into multiple languages. Participants: Respondents to the Global Drug Survey who provided details on N2O use and the experience of paraesthesia in the previous 12 months. Measurements: Questions relating to N2O use, peripheral neuropathy, age and gender were explored among last year’s users. Findings: Of 241,566 respondents, 41,181 (17.0%) indicated that they had ever used nitrous oxide; of these, 42.1% had used in the last 12 months. For the final model, data from 16,124 participants who had used N2O in the last 12 months and had provided responses on age, dose, gender and paraesthesia were used. Of these, the number of respondents reporting persistent numbness/tingling (paraesthesia) in their hands or feet was 537 (3.3%). Although the risk was very low among infrequent users, there was a strong dose–response relationship. For people indicating one or two doses per session, the probability of reporting paraesthesia was approximately 0.018 by comparison; for people indicating 100 doses per session the probability was approximately 0.085. The association, between dose and paraesthesia was influenced by gender and age. Conclusion: While infrequent, episodic users are not at risk, a minority of heavy users are at dose-dependent risk of developing serious neurological consequences. Better education and raised awareness of early symptoms are required.

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