scholarly journals In Vitro and Vivo Identification, Metabolism and Action of Xenoestrogens: An Overview

2021 ◽  
Vol 22 (8) ◽  
pp. 4013
Author(s):  
Li-Hsuan Wang ◽  
Li-Ru Chen ◽  
Kuo-Hu Chen
Keyword(s):  
Congenital Malformations ◽  
Chemical Structure ◽  
Reproductive Tract ◽  
Chemical Compounds ◽  
Naturally Occurring ◽  
Hormonal Balance ◽  
Industrial Byproducts ◽  
High Concentrations ◽  
Underlying Mechanisms

Xenoestrogens (XEs) are substances that imitate endogenous estrogens to affect the physiologic functions of humans or other animals. As endocrine disruptors, they can be either synthetic or natural chemical compounds derived from diet, pesticides, cosmetics, plastics, plants, industrial byproducts, metals, and medications. By mimicking the chemical structure that is naturally occurring estrogen compounds, synthetic XEs, such as polychlorinated biphenyls (PCBs), bisphenol A (BPA), and diethylstilbestrol (DES), are considered the focus of a group of exogenous chemical. On the other hand, nature phytoestrogens in soybeans can also serve as XEs to exert estrogenic activities. In contrast, some XEs are not similar to estrogens in structure and can affect the physiologic functions in ways other than ER-ERE ligand routes. Studies have confirmed that even the weakly active compounds could interfere with the hormonal balance with persistency or high concentrations of XEs, thus possibly being associated with the occurrence of the reproductive tract or neuroendocrine disorders and congenital malformations. However, XEs are most likely to exert tissue-specific and non-genomic actions when estrogen concentrations are relatively low. Current research has reported that there is not only one factor affected by XEs, but opposite directions are also found on several occasions, or even different components stem from the identical endocrine pathway; thus, it is more challenging and unpredictable of the physical health. This review provides a summary of the identification, detection, metabolism, and action of XEs. However, many details of the underlying mechanisms remain unknown and warrant further investigation.

Phytoestrogens

1998 ◽  
Vol 4 (1) ◽  
pp. 18-23 ◽  
Author(s):  
Rachel Mackey ◽  
John Eden
Keyword(s):  
Epidemiological Data ◽  
Asian Populations ◽  
Colon Cancers ◽  
Naturally Occurring ◽  
Urinary Levels ◽  
High Dietary Intake ◽  
High Concentrations ◽  
Relative Potencies

Phytoestrogens are defined as naturally occurring compounds found in plants that are structurally and functionally similar to 17-ß oestradiol or that produce oestrogenic effects. They are diphenolic in structure and are most commonly found in cereals, legumes and grasses. There have been numerous classes identified, the mostly highly investigated being isoflavones and lignans. Isoflavones are attenuated oestrogens. They behave both in vivo and in vitro as agonists and antagonists. Genistein and daidzein are found in high concentrations in soy beans and soy products. Their relative potencies as compared to oestradiol are low but they exhibit equivalent levels of bioactivity when tested in high concentrations. Lignans are found in oilseeds, cereals and berries. The main urinary lignans are enterolactone and enterodiol. Most phytoestrogens are modified by gut flora from glycoside precursors to a compound with oestrogenic properties. A high dietary intake of phytoestrogens was first noted to be associated with decreased incidences of certain diseases. This epidemiological data was obtained primarily from studying Asian populations. Soy consumption is highest in Japan, where urinary levels of phytoestrogen metabolites are extremely high and there are lower rates of so-called ‘Western’ diseases, including breast, endometrial, colon cancers as well as atherosclerotic disease. Research to date has focused on the antiproliferative potential of phytoestrogens, primarily genistein both in vitro and in vivo. Their role in the relief of menopausal symptoms, their hypocholesterolaemic effects and bone resorption protection have been investigated to some extent with promising results. A brief overview of the background of, and the research into, phytoestrogens will be provided in this article.

scholarly journals Identification of low micromolar SARS-CoV-2 Mpro inhibitors from hits identified by in silico screens

2020 ◽  
Author(s):  
Giacomo G. Rossetti ◽  
Marianna Ossorio ◽  
Samia Barriot ◽  
Laurence Tropia ◽  
Vasilis S. Dionellis ◽  
...  
Keyword(s):  
Life Cycle ◽  
Inhibitory Activity ◽  
In Silico ◽  
Chemical Structure ◽  
Chemical Compounds ◽  
Activity Assay ◽  
Biochemical Assays ◽  
Main Protease ◽  
Thermal Shift

ABSTRACTMpro, also known as 3CLpro, is the main protease of the SARS-CoV-2 coronavirus and, as such, is essential for the viral life cycle. Two studies have each screened and ranked in silico more than one billion chemical compounds in an effort to identify putative inhibitors of Mpro. More than five hundred of the seven thousand top-ranking hits were synthesized by an external supplier and examined with respect to their activity in two biochemical assays: a protease activity assay and a thermal shift assay. Two clusters of chemical compounds with Mpro inhibitory activity were identified. An additional five hundred molecules, analogues of the compounds in the two clusters described above, were also synthesized and characterized in vitro. The study of the analogues revealed that the compounds of the first cluster acted by denaturing Mpro and might denature other proteins as well. In contrast, the compounds of the second cluster targeted Mpro with much greater specificity and enhanced its melting temperature, consistent with the formation of stable Mpro-inhibitor complexes. The most active compounds of the second cluster exhibited IC50 values between 4 and 7 μM and their chemical structure suggests that they could serve as leads for the development of potent Mpro inhibitors.

046. FUTURE PROOFING AUSTRALIA'S MAMMALIAN BIODIVERSITY USING GENOME RESOURCE BANKING AND ART: WHERE ARE WE UP TO?

2009 ◽  
Vol 21 (9) ◽  
pp. 11
Author(s):  
S. D. Johnston ◽  
J. Gosalvez ◽  
W. V. Holt
Keyword(s):  
Structural Changes ◽  
Reproductive Tract ◽  
Sperm Chromatin ◽  
Genetic Management ◽  
Lack Of Information ◽  
Gamete Biology ◽  
High Concentrations ◽  
Chromatin Relaxation ◽  
Holding Back

The establishment of a functional genome resource bank for the genetic management and future proofing of Australian native mammals sounds great in theory, but what is the reality of this idea. In order to understand the current rate of progress in this area, we will present an overview of the inherent structural and physiological limitations of non-eutherian mammalian reproduction in terms of gamete biology and ART. For the male, these include (1) an unique mode of spermatid condensation that imparts the need for major structural changes to sperm morphology during epididymal transit, (2) a lack of cysteine protamines and disulphide bonds in the sperm chromatin that predisposes the nucleus to post-thaw chromatin relaxation, (3) an extremely stable acrosome, which to date, has not been possible to experimentally react in vitro, (4) unusual lipid composition in the plasma membrane that potentially makes the sperm cell resistant to cold shock trauma and (5) the need, in some species, for extremely high concentrations of cryoprotectant, that paradoxically, appear to be cytotoxic to the spermatozoon. Female limitations include, (1) the production of a large yolky oocyte and resulting embryo, making it difficult to cryopreserve, (2) a small and technically challenging complex reproductive tract that makes gamete recovery and artificial insemination problematic and (3) a general lack of information on marsupial reproductive physiology and behaviour that has hindered the development of protocols for timed induction of oestrus and ovulation. We shall also identify, socio-political and ethical limitations holding back the application of assisted breeding technology in these species.

Naturally Occurring Level of Aflatoxin B1 Injures Human, Canine and Bovine Leukocytes Through ATP Depletion and Caspase Activation

2019 ◽  
Vol 39 (1) ◽  
pp. 30-38 ◽  
Author(s):  
Jalil Mehrzad ◽  
Fatemeh Fazel ◽  
Nazaninzeynam Pouyamehr ◽  
Saman Hosseinkhani ◽  
Hesam Dehghani
Keyword(s):  
Flow Cytometry ◽  
Caspase 3 ◽  
Companion Animals ◽  
Atp Depletion ◽  
Caspase Activation ◽  
Viability Assay ◽  
Naturally Occurring ◽  
Old Persian ◽  
Underlying Mechanisms

Aflatoxin (AF) B1 is a potent hepatotoxic, mutagenic, teratogenic mycotoxin and may cause immune suppression/dysregulation in humans and animals. Toxic effects of AFB1 on key mammalian immune cells (ie, leukocytes) needs to be mechanistically elucidated. In this study, along with the determination of AFB1’s LC50 for certain leukocytes, we analyzed the effect of naturally occurring levels of AFB1 on apoptosis/necrosis of neutrophils, lymphocytes, and monocytes from healthy young humans (20- to 25-year-old male), dogs (1- to 2-year-old Persian/herd breed), and cattle (1- to 2-year-old cattle). Leukocytes were incubated for approximately 24 hours with naturally occurring levels of AFB1 (10 ng/mL). Intracellular adenosine triphosphate (ATP) depletion and caspase-3/7 activity were then determined by luciferase-dependent bioluminescence (BL). Furthermore, the necrotic leukocytes were measured using propidium iodide (PI)-related flow cytometry. A significant decrease (24%-45%, 33.2% ± 2.7%) in intracellular ATP content was observed in AFB1-treated neutrophils, lymphocytes, and monocytes in all studied mammals. Also, with such a low level (10 ng/mL) of AFB1, BL-based caspase-3/7 activity (BL intensity) in all 3 tested mammalian leukocyte lineages was noticeably increased (∼>2-fold). Flow cytometry-based PI staining (for viability assay) of the AFB1-treated leukocytes showed slightly/insignificantly more increase of necrotic (PI+) neutrophils, lymphocytes, and monocytes in human, dogs, and cattle. Even though in vitro LC50s for AFB1’ (∼20,000-40,000 ng/mL) were approximately 2,000 to 4,000 times higher than background, these studies demonstrate leukocytes from human and farm/companion animals are sensitive to naturally occurring levels of AFB1. The observed in vitro ATP depletion and caspase activation in AFB1-exposed leukocytes can partially explain the underlying mechanisms of AFB1-induced immune disorders in mammals.

scholarly journals Characterization of 1 alpha-hydroxylation of vitamin D3 sterols by cultured alveolar macrophages from patients with sarcoidosis.

1985 ◽  
Vol 161 (4) ◽  
pp. 755-765 ◽  
Author(s):  
J S Adams ◽  
M A Gacad
Keyword(s):  
Vitamin D3 ◽  
Alveolar Macrophages ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Dihydroxyvitamin D3 ◽  
Naturally Occurring ◽  
Hydroxylation Reaction ◽  
High Concentrations

We investigated the 1 alpha-hydroxylation of vitamin D3 sterols by cultured pulmonary alveolar macrophages (PAM) from patients with sarcoidosis with or without clinically abnormal calcium homeostasis. Like the naturally occurring renal 1 alpha-hydroxylase, the PAM 1 alpha-hydroxylation reaction exhibited a high affinity for 25-hydroxyvitamin D3 (25-OH-D3) and a preference for substrates containing a 25-hydroxyl group in the side chain of the sterol. Unlike the renal enzyme, the PAM 1 alpha-hydroxylating mechanism was not accompanied by 24-hydroxylating activity, even after preincubation with 75 nM 1,25-dihydroxyvitamin D3 [1,25-(OH)2-D3] or exposure to high concentrations of substrate (500 nM 25-OH-D3). The PAM 25-OH-D3-1 alpha-hydroxylation reaction was stimulated by gamma interferon and inhibited by exposure to the glucocorticoid dexamethasone. The characteristics of the PAM hydroxylation process in vitro appear to reflect the efficiency of the extrarenal production of 1,25-(OH)2-D3 and the therapeutic efficacy of glucocorticoids in patients with sarcoidosis and disordered calcium metabolism.

scholarly journals Actin filament alignment causes mechanical hysteresis in cross-linked networks

2021 ◽  
Author(s):  
Danielle R. Scheff ◽  
Steven A. Redford ◽  
Chatipat Lorpaiboon ◽  
Sayantan Majumdar ◽  
Aaron R. Dinner ◽  
...  
Keyword(s):  
Model System ◽  
Mechanical Adaptation ◽  
Mechanical Hysteresis ◽  
Initial Network ◽  
Low Concentrations ◽  
Applied Shear Stress ◽  
Cross Linker ◽  
High Concentrations ◽  
Underlying Mechanisms

AbstractCells dynamically control their material properties through remodeling of the actin cytoskeleton, an assembly of cross-linked networks and bundles formed from the biopolymer actin. We recently found that cross-linked networks of actin filaments reconstituted in vitro can exhibit adaptive behavior and thus serve as a model system to understand the underlying mechanisms of mechanical adaptation of the cytoskeleton. In these networks, training, in the form of applied shear stress, can induce asymmetry in the nonlinear elasticity. Here, we explore control over this mechanical hysteresis by tuning the concentration and mechanical properties of cross-linking proteins in both experimental and simulated networks. We find that this effect depends on two conditions: the initial network must exhibit nonlinear strain stiffening, and filaments in the network must be able to reorient during training. Hysteresis depends strongly and non-monotonically on cross-linker concentration, with a peak at moderate concentrations. In contrast, at low concentrations, where the network does not strain stiffen, or at high concentrations, where filaments are less able to rearrange, there is little response to training. Additionally, we investigate the effect of changing cross-linker properties and find that longer or more flexible cross-linkers enhance hysteresis. Remarkably plotting hysteresis against alignment after training yields a single curve regardless of the physical properties or concentration of the cross-linkers.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

Aggregation of Cat Platelets in Vitro

1970 ◽  
Vol 23 (03) ◽  
pp. 601-620 ◽  
Author(s):  
Th. B Tschopp
Keyword(s):  
Adenosine Monophosphate ◽  
Blood Collection ◽  
Base Line ◽  
Reversible Aggregation ◽  
Low Concentrations ◽  
Irreversible Aggregation ◽  
High Concentrations ◽  
Two Phases ◽  
Improved Technique

SummaryAggregation of cat platelets in the citrated plasma is examined by means of Born’s absorptiometer. A marked tendency of the platelets of this species to spontaneous aggregation necessitated first of all the development of an improved technique of blood collection.A hypothesis according to which 5-HT is released from the platelets, explains the absence of oscillations on the base line of the absorptiometer, the absence of platelet swelling, when ADP is added, and the effect of stirring on the aggregation curves in cat PRP. The average volume of cat platelets amounts to 10.46 μ3 when directly fixed in the blood, when fixed from PRP to 12.17 μ3, when fixed from stirred PRP to 13.51 μ3.In low concentrations (0.3-2 μM) ADP produce reversible aggregation; in narrowly restricted, individually dissimilar mean concentrations irreversible aggregation in two phases and in high concentrations, irreversible aggregation in one phase. Like ADP serotonin produces 2 phase irreversible aggregation in concentrations of 3-10 μM, but unlike ADP, the aggregation velocity decreases again with high 5-HT concentrations (>100 μM). Adrenaline does not produce aggregation and it is likely that adenosine and adenosine monophosphate inhibit the aggregation by serotonin but not by ADP. Species differences in the aggregation of human, rabbit and cat platelets are discussed.

Thrombin Generation Measured Ex Vivo Following Microvasculor Injury Is Increased in SLE Patients with Antiphospholipid-protein Antibodies

1997 ◽  
Vol 78 (04) ◽  
pp. 1173-1177 ◽  
Author(s):  
Jacek Musiał ◽  
Jakub Swadźba ◽  
Miłosz Jankowski ◽  
Marek Grzywacz ◽  
Stanisława Bazan-Socha ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Thrombin Generation ◽  
Ex Vivo ◽  
Skin Incision ◽  
Anticardiolipin Antibodies ◽  
Small Blood Vessel ◽  
Anionic Phospholipids ◽  
Increased Risk ◽  
High Concentrations

SummaryAntiphospholipid-protein antibodies (APA) include lupus-type anticoagulant (LA) and antibodies recognizing complexes of anionic phospholipids (e.g. cardiolipin) and proteins (e.g. prothrombin and (β2-glycoprotein I). The presence of APA is associated with an increased risk of both arterial and venous thrombosis. However, the pathogenic mechanism leading to thrombosis in patients with APA remains unclear. We studied 32 patients with systemic lupus erythematosus (SLE) who were divided into two groups depending on the presence (n = 19) or absence (n = 13) of APA. Healthy volunteers (n = 12) matched by age and sex served as controls. In all subjects LA and IgG class anticardiolipin antibodies (ACA) were determined. Thrombin generation was monitored ex vivo measuring fibrinopeptide A (FPA) and prothrombin fragment F1 + 2 (F1 + 2) in blood emerging from a skin microvasculature injury, collected at 30 second intervals. In subjects with antiphospholipid antibodies mean FPA and F1 + 2 concentrations were signiF1cantly higher at most blood sampling times than in controls. In some SLE patients with APA the process of thrombin generation was clearly disturbed and very high concentrations of F1brinopeptide A were detected already in the F1rst samples collected. Two minutes after skin incision SLE patients without APA produced slightly more FPA, but not F1 + 2, as compared to healthy subjects. Mathematical model applied to analyze the thrombin generation kinetics revealed that APA patients generated signiF1cantly greater amounts of thrombin than healthy controls (p = 0.02 for either marker). In contrast, in the same patients generation of thrombin in recalciF1ed plasma in vitro was delayed pointing to the role of endothelium in the phenomenon studied. In summary, these data show for the F1rst time that in SLE patients with antiphospholipid-protein antibodies thrombin generation after small blood vessel injury is markedly increased. Enhanced thrombin generation might explain thrombotic tendency observed in these patients.

Inhibition of Platelet Function by Antiarrhythmic Drugs, Verapamil and Disopyramide

1982 ◽  
Vol 47 (02) ◽  
pp. 150-153 ◽  
Author(s):  
P Han ◽  
C Boatwright ◽  
N G Ardlie
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Antiarrhythmic Drugs ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Second Phase ◽  
Ionophore A23187 ◽  
High Concentrations ◽  
Artery Disease

SummaryVarious cardiovascular drugs such as nitrates and propranolol, used in the treatment of coronary artery disease have been shown to have an antiplatelet effect. We have studied the in vitro effects of two antiarrhythmic drugs, verapamil and disopyramide, and have shown their inhibitory effect on platelet function. Verapamil, a calcium channel blocker, inhibited the second phase of platelet aggregation induced by adenosine diphosphate (ADP) and inhibited aggregation induced by collagen. Disopyramide similarly inhibited the second phase of platelet aggregation caused by ADP and aggregation induced by collagen. Either drug in synergism with propranolol inhibited ADP or collagen-induced platelet aggregation. Disopyramide at high concentrations inhibited arachidonic add whereas verapamil was without effect. Verapamil, but not disopyramide, inhibited aggregation induced by the ionophore A23187.

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