A direct effect of 24,25-(OH)2D3 and 1,25-(OH)2D3 on the modeling of fetal mice long bones in vitro

SummaryIn the course of studying the effects on platelets of the oxidant species superoxide (O- 2), Of was generated by the interaction of xanthine oxidase plus xanthine. Surprisingly, gel-filtered platelets, when exposed to xanthine oxidase in the absence of xanthine substrate, were found to generate superoxide (O- 2), as determined by the reduction of added cytochrome c and by the inhibition of this reduction in the presence of superoxide dismutase.In addition to generating Of, the xanthine oxidase-treated platelets display both aggregation and evidence of the release reaction. This xanthine oxidase induced aggreagtion is not inhibited by the addition of either superoxide dismutase or cytochrome c, suggesting that it is due to either a further metabolite of O- 2, or that O- 2 itself exerts no important direct effect on platelet function under these experimental conditions. The ability of Of to modulate platelet reactions in vivo or in vitro remains in doubt, and xanthine oxidase is an unsuitable source of O- 2 in platelet studies because of its own effects on platelets.

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Angiogenic Effect of Pravastatin Alone and with Sera from Healthy and Complicated Pregnancies Studied by in vitro Vasculogenesis/Angiogenesis Assay

Journal of Vascular Research ◽

10.1159/000512831 ◽

2021 ◽

pp. 1-9

Author(s):

Anita Virtanen ◽

Outi Huttala ◽

Kati Tihtonen ◽

Tarja Toimela ◽

Tuula Heinonen ◽

...

Keyword(s):

Direct Effect ◽

Late Onset ◽

Maternal Serum ◽

In Vitro Assay ◽

Serum Samples ◽

Therapeutic Concentration ◽

Tubule Formation ◽

Vitro Assay ◽

Angiogenesis Assay

Objective: To determine the direct effect of pravastatin on angiogenesis and to study the interaction between pravastatin and maternal sera from women with early- or late-onset pre-eclampsia (PE), intrauterine growth restriction, or healthy pregnancy. Methods: We collected 5 maternal serum samples from each group. The effect of pravastatin on angiogenesis was assessed with and without maternal sera by quantifying tubule formation in a human-based in vitro assay. Pravastatin was added at 20, 1,000, and 8,000 ng/mL concentrations. Concentrations of angiogenic and inflammatory biomarkers in serum and in test medium after supplementation of serum alone and with pravastatin (1,000 ng/mL) were measured. Results: Therapeutic concentration of pravastatin (20 ng/mL) did not have significant direct effect on angiogenesis, but the highest concentrations inhibited angiogenesis. Pravastatin did not change the levels of biomarkers in the test media. There were no changes in angiogenesis when therapeutic dose of pravastatin was added with maternal sera, but there was a trend to wide individual variation towards enhanced angiogenesis, particularly in the early-onset PE group. Conclusions: At therapeutic concentration, pravastatin alone or with maternal sera has no significant effect on angiogenesis, but at high concentrations the effect seems to be anti-angiogenic estimated by in vitro assay.

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Kindlin-2 mediates mechanotransduction in bone by regulating expression of Sclerostin in osteocytes

Communications Biology ◽

10.1038/s42003-021-01950-4 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Lei Qin ◽

Xuekun Fu ◽

Jing Ma ◽

Manxia Lin ◽

Peijun Zhang ◽

...

Keyword(s):

Bone Loss ◽

Mechanical Stimulation ◽

Fluid Shear Stress ◽

Weight Bearing ◽

Underlying Mechanism ◽

Long Bones ◽

Cell Orientation ◽

Cytoskeleton Organization

AbstractOsteocytes act as mechanosensors in bone; however, the underlying mechanism remains poorly understood. Here we report that deleting Kindlin-2 in osteocytes causes severe osteopenia and mechanical property defects in weight-bearing long bones, but not in non-weight-bearing calvariae. Kindlin-2 loss in osteocytes impairs skeletal responses to mechanical stimulation in long bones. Control and cKO mice display similar bone loss induced by unloading. However, unlike control mice, cKO mice fail to restore lost bone after reloading. Osteocyte Kindlin-2 deletion impairs focal adhesion (FA) formation, cytoskeleton organization and cell orientation in vitro and in bone. Fluid shear stress dose-dependently increases Kindlin-2 expression and decreases that of Sclerostin by downregulating Smad2/3 in osteocytes; this latter response is abolished by Kindlin-2 ablation. Kindlin-2-deficient osteocytes express abundant Sclerostin, contributing to bone loss in cKO mice. Collectively, we demonstrate an indispensable novel role of Kindlin-2 in maintaining skeletal responses to mechanical stimulation by inhibiting Sclerostin expression during osteocyte mechanotransduction.

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In vitro evaluation of the direct effect of estradiol on human osteoblasts (HOB) and human mesenchymal stem cells (h-MSCs)

Injury ◽

10.1016/j.injury.2006.08.022 ◽

2006 ◽

Vol 37 (3) ◽

pp. S33-S42 ◽

Cited By ~ 29

Author(s):

Lucy DiSilvio ◽

Jacqueline Jameson ◽

Zakareya Gamie ◽

Peter V. Giannoudis ◽

Eleftherios Tsiridis

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Direct Effect ◽

Human Mesenchymal Stem Cells ◽

Human Osteoblasts ◽

In Vitro Evaluation

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THE INTERACTION OF ENZYMES AND HORMONES

PEDIATRICS ◽

10.1542/peds.26.3.476 ◽

1960 ◽

Vol 26 (3) ◽

pp. 476-481

Author(s):

Abraham White

Keyword(s):

Direct Effect ◽

Chemical Reactions ◽

Elevated Temperatures ◽

Enzyme System ◽

Enzymic Activity ◽

Hormone Interaction ◽

Indirect Influence ◽

Rare Exception ◽

Hormonal Action

The majority of living forms depend for their functioning upon two classes of biocatalysts, the enzymes and the hormones. These biocatalysts permit the diverse chemical reactions of the organism to proceed at 38°C with a specificity and at rates frequently unattainable in vitro at elevated temperatures with similar reactants. The physiologic importance of enzymes and hormones is evident not only under normal circumstances, but is reflected clinically in the diverse descriptions of errors of metabolism, due to lack or deficiency of one or more enzymes, and the numerous hypo- and hyperfunctioning states resulting from imbalance of hormonal supply. Inasmuch as both enzymes and hormones function, with rare exception, to accelerate the rates of processes in cells, investigators have sought possible interrelationships and interactions of enzymes and hormones, particularly as a basis for the mechanism of hormonal action. It has seemed logical to hypothesize that hormones, while not essential for reactions to proceed but nevertheless affecting the rates of reactions, may function by altering either the concentration or activity of the prime cellular catalysts, the enzymes. This proposed influence of hormones on enzymic activity might be a primary, direct effect achieved by the hormone participating as an integral part of an enzyme system, or an indirect influence based upon the hormone altering the concentration of available enzyme and/or substrate utilized by a particular enzyme. It is the purpose of this presentation to describe a relatively few, but better defined, examples of the more direct relationships of enzymes and hormones. Five examples of enzyme-hormone interaction will be presented, based on the criterion that an effect of the hormone has been demonstrated on addition of the hormone in vitro to a purifled, or partially purified, enzyme system.

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Sandostatin has no direct effect on ovarian steroidogenesis in vitro

Human Reproduction ◽

10.1093/oxfordjournals.humrep.a138052 ◽

1993 ◽

Vol 8 (3) ◽

pp. 364-368 ◽

Cited By ~ 6

Author(s):

L.A. Pawelczyk ◽

A.J. Duleba ◽

Y.S. Moon ◽

B.Ho Yuen

Keyword(s):

Direct Effect ◽

Ovarian Steroidogenesis

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Direct effect of parathyroid hormone on insulin secretion from pancreatic islets

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1990.258.6.e975 ◽

1990 ◽

Vol 258 (6) ◽

pp. E975-E984 ◽

Cited By ~ 5

Author(s):

G. Z. Fadda ◽

M. Akmal ◽

L. G. Lipson ◽

S. G. Massry

Keyword(s):

Insulin Secretion ◽

Parathyroid Hormone ◽

Pancreatic Islets ◽

Insulin Release ◽

Direct Effect ◽

Indirect Evidence ◽

Cytosolic Calcium ◽

Dependent Manner ◽

Stimulation Of

Indirect evidence indicates that parathyroid hormone (PTH) interacts with pancreatic islets and modulates their insulin secretion. This property of PTH has been implicated in the genesis of impaired insulin release in chronic renal failure. We examined the direct effect of PTH-(1-84) and PTH-(1-34) on insulin release using in vitro static incubation and dynamic perifusion of pancreatic islets from normal rats. Both moieties of the hormone stimulated in a dose-dependent manner glucose-induced insulin release but higher doses inhibited glucose-induced insulin release. This action of PTH was modulated by the calcium concentration in the media. The stimulatory effect of PTH was abolished by its inactivation and blocked by its antagonist [Tyr-34]bPTH-(7-34)NH2. PTH also augmented phorbol ester (TPA)-induced insulin release, stimulated adenosine 3',5'-cyclic monophosphate (cAMP) generation by pancreatic islets, and significantly increased (+50 +/- 2.7%, P less than 0.01) their cytosolic calcium. Verapamil inhibited the stimulatory effect of PTH on insulin release. The data show that 1) pancreatic islets are a PTH target and may have PTH receptors, 2) stimulation of glucose-induced insulin release by PTH is mediated by a rise in cytosolic calcium, 3) stimulation of cAMP production by PTH and a potential indirect activation of protein kinase C by PTH may also contribute to the stimulatory effect on glucose-induced insulin release, and 4) this action of PTH requires calcium in incubation or perifusion media.

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Longitudinal bone growth in vitro: effects of insulin-like growth factor I and growth hormone

Acta Endocrinologica ◽

10.1530/acta.0.1240602 ◽

1991 ◽

Vol 124 (5) ◽

pp. 602-607 ◽

Cited By ~ 36

Author(s):

Ben A. A. Scheven ◽

Nicola J. Hamilton

Keyword(s):

Growth Hormone ◽

Growth Factor ◽

Bone Growth ◽

Long Bone ◽

Long Bones ◽

Insulin Like Growth Factor ◽

Serum Free ◽

Factor I ◽

Igf I

Abstract. Longitudinal growth was studied using an in vitro model system of intact rat long bones. Metatarsal bones from 18- and 19-day-old rat fetuses, entirely (18 days) or mainly (19 days) composed of chondrocytes, showed a steady rate of growth and radiolabelled thymidine incorporation for at least 7 days in serum-free media. Addition of recombinant human insulin-like growth factor-I to the culture media resulted in a direct stimulation of the longitudinal growth. Recombinant human growth hormone was also able to stimulate bone growth, although this was generally accomplished after a time lag of more than 2 days. A monoclonal antibody to IGF-I abolished both the IGF-I and GH-stimulated growth. However, the antibody had no effect on the growth of the bone explants in control, serum-free medium. Unlike the fetal long bones, bones from 2-day-old neonatal rats were arrested in their growth after 1-2 days in vitro. The neonatal bones responded to IGF-I and GH in a similar fashion as the fetal bones. Thus in this study in vitro evidence of a direct effect of GH on long bone growth via stimulating local production of IGF by the growth plate chondrocytes is presented. Furthermore, endogenous growth factors, others than IGFs, appear to play a crucial role in the regulation of fetal long bone growth.

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136 EVIDENCE OF A DIRECT EFFECT OF P4 ON IVF-DERIVED BOVINE 8-CELL EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv17n2ab136 ◽

2005 ◽

Vol 17 (2) ◽

pp. 219 ◽

Cited By ~ 5

Author(s):

C.E. Ferguson ◽

T.R. Davidson ◽

M.R.B. Mello ◽

A.S. Lima ◽

D.J. Kesler ◽

...

Keyword(s):

Embryo Development ◽

Direct Effect ◽

Blastocyst Stage ◽

Control Group ◽

Bovine Embryo ◽

Bovine Embryos ◽

Direct Role ◽

Treatment Groups ◽

And Control

There has been much debate over a direct role for progesterone (P4) in early bovine embryo development. While previous attempts to supplement bovine embryos in vitro with P4 produced results that vary and are often contradictory, this may be a response of administering P4 at inappropriate times. Therefore, the objective of these experiments was to determine if P4 could exert a direct effect on developing IVF-derived bovine embryos when administered at an appropriate time of embryo development. In Exp. I, IVF-derived bovine 8-cell embryos were randomly allotted to treatments: (1) control, CR1aa medium (n = 168); (2) vehicle, CR1aa + ETOH (0.01%) (n = 170); and (3) P4, CR1aa + ETOH + P4 (20 ng/mL in 50-μL droplet) (n = 173). In Exp. II, IVF-derived bovine 8-cell embryos were randomly allotted to treatments: (1) control, CR1aa medium (n = 160); (2) vehicle, CR1aa + DMSO (0.01%) (n = 180); and (3) P4, CR1aa + DMSO (0.01%) + P4 (20 ng/mL in 50-μL droplet) (n = 170). All embryos were evaluated on Days 6 to 9 post-insemination and rates calculated from 8-cell embryos. In Exp. I, ETOH tended to have a detrimental effect with significantly fewer (P < 0.05) embryos (53%) developing to the blastocyst stage on Day 7 compared with the control (62%) and P4 (71%) groups. At Day 7, significantly more embryos cultured in P4 (71%) developed to the blastocyst stage compared with the control group (62%). P4 treatment significantly increased the number of Grade 1 blastocysts (25%) on Day 7 compared with vehicle (15%) and control (17%) groups. At the end of culture, there were also significantly more Day 9 hatched blastocysts in the P4 group (33%) compared with vehicle (22%) and control (21%) groups. Supplementing P4 in the culture medium increased the rate of development, resulting in significantly more blastocysts (8%) on Day 6 and hatched blastocysts (21%) on Day 8 compared with vehicle (3% and 12%) and control (0% and 8%) groups, respectively. In Exp. II, there were no significant differences between treatment groups for Day 7 blastocysts (control 54%, DMSO 61%, P4 57%) and Day 9 hatched blastocysts (control 46%, DMSO 51%, P4 46%). However, there were significantly more Grade 1 blastocysts in the P4 group (22% and 36%) on Days 6 and 8 compared with vehicle (11% and 23%) and control (13% and 23%) groups, respectively. The lack of improvement in Day 7 blastocysts and Day 9 hatched blastocysts rates leads to further uncertainty in understanding the P4 vehicle interactions. In conclusion, the results of these two experiments indicate that P4 can exert a direct effect on the developing IVF-derived bovine embryo; however, due to P4 vehicle interactions; other inert vehicles need to be explored to further evaluate the direct effects of P4 on the developing bovine embryo.

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