scholarly journals Studies of cholesterol biosynthesis. 1. A new chemical degradation of cholesterol

1953 ◽  
Vol 54 (4) ◽  
pp. 590-597 ◽  
Author(s):  
J. W. Cornforth ◽  
G. D. Hunter ◽  
G. Popják
Keyword(s):  
Cholesterol Biosynthesis ◽  
Chemical Degradation

scholarly journals The incorporation of a hydrogen atom at C-15 of cholesterol biosynthesized from squalene

1969 ◽  
Vol 114 (4) ◽  
pp. 801-806 ◽  
Author(s):  
M Akhtar ◽  
A. D. Rahimtula ◽  
D. C. Wilton
Keyword(s):  
Hydrogen Atom ◽  
Cholesterol Biosynthesis ◽  
Tritiated Water ◽  
Total Radioactivity ◽  
Chemical Degradation

Cholesterol is biosynthesized from squalene in the presence of tritiated water. Chemical degradation reveals that a considerable percentage of the total radioactivity is present at C-15. This result confirms the previous observations on the involvement of a C-15 hydrogen atom in cholesterol biosynthesis.

The Effect of Oxidized Cholesterol on the Aorta of Rabbits- Scanning Electron Microscopic Observations

1982 ◽  
Vol 40 ◽  
pp. 340-341
Author(s):  
S. K. Pena ◽  
C. B. Taylor ◽  
J. Hill ◽  
J. Safarik
Keyword(s):  
Cholesterol Biosynthesis ◽  
Cholesterol Content ◽  
Arterial Injury ◽  
Electron Microscopic ◽  
Aortic Smooth Muscle ◽  
Oxidized Cholesterol ◽  
Initial Event ◽  
Membrane Structure And Function ◽  
Scanning Electron Microscopic ◽  
And Function

Introduction: Oxidized cholesterol derivatives have been demonstrated in various cell cultures to be very potent inhibitors of 3-hvdroxy-3- methylglutaryl Coenzyme A reductase which is a principle regulator of cholesterol biosynthesis in the cell. The cholesterol content in the cells exposed to oxidized cholesterol was found to be markedly decreased. In aortic smooth muscle cells, the potency of this effect was closely related to the cytotoxicity of each derivative. Furthermore, due to the similarity of their molecular structure to that of cholesterol, these oxidized cholesterol derivatives might insert themselves into the cell membrane, alter membrane structure and function and eventually cause cell death. Arterial injury has been shown to be the initial event of atherosclerosis.

A generic fluticasone propionate and salmeterol dry powder inhaler: Evidence of usability, function, and robustness

2021 ◽  
Vol 42 (1) ◽  
pp. 30-35 ◽  
Author(s):  
Donald P. Tashkin ◽  
Arkady Koltun ◽  
Róisín Wallace
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Fluticasone Propionate ◽  
Healthy Volunteers ◽  
Pulmonary Disease ◽  
Dry Powder Inhaler ◽  
Chemical Degradation ◽  
Chronic Obstructive ◽  
Dry Powder ◽  
Obstructive Pulmonary Disease ◽  
Flow Rates

Background: A generic combination of fluticasone propionate and salmeterol xinafoate inhalation powder in a premetered, multidose, nonreusable inhaler was recently approved. Objective: To assess the performance of the generic device. Methods: Findings from three studies with regard to device usability, function, and robustness were reviewed. Results: In a study to assess device function in patients and healthy volunteers, the generic device was successfully used by patients with asthma and chronic obstructive pulmonary disease who were either dry powder inhaler users or dry powder inhaler‐naive, even though they were not trained beyond being provided the instructions for use. In a study to measure inhaled flow rates generated by patients and healthy volunteers, the generic device consistently simulated the delivery of a full dose of drug, even to patients with severe respiratory disease and reduced inspiratory flow rates. Although the generic device had a slightly higher airflow resistance, this study demonstrated that this difference did not result in any clinically meaningful differences in terms of drug delivery. Pressure drop, a key parameter that drives the fluidization and aerosolization of the powder dose, was found to be comparable between the devices. In an open-label study, the generic device met all U.S. Food and Drug Administration specifications for device robustness after 21.5 days of twice-daily dosing via oral inhalation among 111 participants with asthma or chronic obstructive pulmonary disease. All inhalers tested demonstrated conformity with a pharmacopeia with respect to key quality parameters (assay, delivered dose uniformity, aerodynamic size distribution). There was no evidence of chemical degradation of the active ingredients, nor of microbial or water ingress into the powder, as a result of inhaler use.

scholarly journals Characterizing the Role of HMG-CoA Reductase in Aryl Hydrocarbon Receptor-Mediated Liver Injury in C57BL/6 Mice

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Peter Dornbos ◽  
Amanda Jurgelewicz ◽  
Kelly A. Fader ◽  
Kurt Williams ◽  
Timothy R. Zacharewski ◽  
...  
Keyword(s):  
Liver Injury ◽  
Aryl Hydrocarbon Receptor ◽  
Cholesterol Biosynthesis ◽  
Competitive Inhibitor ◽  
Cholesterol Homeostasis ◽  
Hepatic Glycogen ◽  
Alcoholic Fatty Liver ◽  
Female Mice ◽  
Aryl Hydrocarbon ◽  
The Impact

Abstract The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor. The prototypical ligand of the AHR is an environmental contaminant called 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD exposure is associated with many adverse health outcomes in humans including non-alcoholic fatty liver disease (NAFLD). Previous studies suggest that AHR ligands alter cholesterol homeostasis in mice through repression of genes involved in cholesterol biosynthesis, such as Hmgcr, which encodes the rate-limiting enzyme of cholesterol biosynthesis called 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGCR). In this study, we sought to characterize the impact of HMGCR repression in TCDD-induced liver injury. C57BL/6 mice were exposed to TCDD in the presence or absence of simvastatin, a competitive inhibitor of HMGCR. Simvastatin exposure decreased TCDD-induced hepatic lipid accumulation in both sexes, but was most prominent in females. Simvastatin and TCDD (S + T) co-treatment increased hepatic AHR-battery gene expression and liver injury in male, but not female, mice. In addition, the S + T co-treatment led to an increase in hepatic glycogen content that coincides with heavier liver in female mice. Results from this study suggest that statins, which are amongst the most prescribed pharmaceuticals, may protect from AHR-mediated steatosis, but alter glycogen metabolism and increase the risk of TCDD-elicited liver damage in a sex-specific manner.

Mechanism of Perfluorsulfonic Acid Membrane Chemical Degradation Under Low RH Conditions

2013 ◽  
Vol 50 (2) ◽  
pp. 907-918 ◽  
Author(s):  
F. D. Coms ◽  
H. Xu ◽  
T. McCallum ◽  
C. Mittelsteadt
Keyword(s):  
Chemical Degradation

scholarly journals Cardiovascular disease and osteoporosis: is there a link between lipids and bone?

2002 ◽  
Vol 39 (3) ◽  
pp. 203-210 ◽  
Author(s):  
John R Burnett ◽  
Samuel D Vasikaran
Keyword(s):  
Cardiovascular Disease ◽  
Bone Density ◽  
Vascular Calcification ◽  
Cholesterol Biosynthesis ◽  
Hormone Replacement ◽  
Plasma Lipid ◽  
Clinical Effects ◽  
Cardiovascular Morbidity And Mortality ◽  
The Relationship

Atherosclerotic heart disease and osteoporosis are both diseases of old age. Evidence is accumulating for a link between vascular and bone disease. Calcification is a common feature of atherosclerotic plaques, and osteoporosis is associated with both atherosclerosis and vascular calcification. However, the relationship of vascular calcification to the pathogenesis of atherosclerosis remains incompletely understood. Hormone replacement therapy has beneficial effects in the prevention of both atherosclerosis and osteoporosis. Bisphosphonates inhibit bone resorption and are used in the treatment of osteoporosis, whereas the statins inhibit cholesterol biosynthesis and are used for the treatment of atherosclerosis. We have reviewed recent advances in the knowledge of the actions of bisphosphonates and statins at the cellular, molecular and end-organ levels in order to examine the relationship between cardiovascular disease and osteoporosis and to explore the link between lipids and bones. These studies suggest that the mechanism of actions of these two classes of drugs at the cellular level may not be mutually exclusive. There are some early clinical data to complement these findings, suggesting that statins increase bone density and bisphosphonates may have a beneficial effect in vivo on plasma lipid levels and on the atherosclerotic process. Properly designed prospective studies that examine the effect of statins on bone density and fractures, as well as the effects of bisphosphonates on lipid profiles, atherosclerotic progression and cardiovascular morbidity and mortality are needed to define clearly the clinical effects and potential new roles for these agents.

scholarly journals High-throughput transcriptomic analysis of human primary hepatocyte spheroids exposed to per- and polyfluoroalkyl substances (PFAS) as a platform for relative potency characterization

2021 ◽  
Author(s):  
A Rowan-Carroll ◽  
A Reardon ◽  
K Leingartner ◽  
R Gagné ◽  
A Williams ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cholesterol Biosynthesis ◽  
Health Hazard ◽  
Biological Responses ◽  
Similar Gene Expression Profile ◽  
Transcriptional Changes ◽  
Hazard And Risk ◽  
Hepatocyte Spheroids ◽  
Similar Gene ◽  
Identify Gene Expression

Abstract Per- and poly-fluoroalkyl substances (PFAS) are widely found in the environment because of their extensive use and persistence. Although several PFAS are well studied, most lack toxicity data to inform human health hazard and risk assessment. This study focussed on four model PFAS: perfluorooctanoic acid (PFOA; 8 carbon), perfluorobutane sulfonate (PFBS; 4 carbon), perfluorooctane sulfonate (PFOS; 8 carbon), and perfluorodecane sulfonate (PFDS; 10 carbon). Human primary liver cell spheroids (pooled from 10 donors) were exposed to 10 concentrations of each PFAS and analyzed at four time-points. The approach aimed to: (1) identify gene expression changes mediated by the PFAS; (2) identify similarities in biological responses; (3) compare PFAS potency through benchmark concentration analysis; and (4) derive bioactivity exposure ratios (ratio of the concentration at which biological responses occur, relative to daily human exposure). All PFAS induced transcriptional changes in cholesterol biosynthesis and lipid metabolism pathways, and predicted PPARα activation. PFOS exhibited the most transcriptional activity and had a highly similar gene expression profile to PFDS. PFBS induced the least transcriptional changes and the highest benchmark concentration (i.e., was the least potent). The data indicate that these PFAS may have common molecular targets and toxicities, but that PFOS and PFDS are the most similar. The transcriptomic bioactivity exposure ratios derived here for PFOA and PFOS were comparable to those derived using rodent apical endpoints in risk assessments. These data provide a baseline level of toxicity for comparison with other known PFAS using this testing strategy.

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