Hemostatic Properties of Infusible Trehalose-Stabilized Lyophilized Platelet Derivatives.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 834-834
Author(s):  
Keith A. Moskowitz ◽  
Josh Dee ◽  
Jason Barnidge ◽  
Ruth Sum ◽  
David Ho ◽  
...  
Keyword(s):  
Fluid Phase ◽  
Fold Increase ◽  
Submicron Particles ◽  
Cell Counting ◽  
Attractive Alternative ◽  
Dependent Manner ◽  
Clot Retraction ◽  
Drug Induced ◽  
Dose Dependent

Abstract Availability of platelet concentrates for treatment of bleeding associated with thrombocytopenia, trauma, or drug-induced coagulopathies is problematic due to the short 5 day platelet storage time and because platelets require controlled shaking at ambient temperature in order to remain viable, a condition which augments bacterial growth. To address the platelet availability problem we expanded upon trehalose cryo-preservation technology to create a lyophilized hemostatic platelet derivative. Washed platelets were stabilized by accumulation of 5–10 mM intracellular trehalose via fluid phase endocytosis then formulated with excipients and lyophilized. Lyophilized platelets were instantaneously rehydrated with > 90% recovery and were stable for at least 3–6 months at ambient temperatures. Rehydrated (RH) platelets responded quantitatively to α-and γ-thrombin and ristocetin by transmittance aggregometry and were partially agglutinated by collagen as judged by aggregometry and single cell counting using the Platelet Works® system. RH platelets co-aggregated in a dose dependent manner when mixed with fresh autologous platelets during collagen-induced activation. Aggregation response to low-dose thrombin and collagen was inhibited by the GPIIb/IIIa antagonist RGDS and by EGTA. RH platelets were quantitatively incorporated into fibrin clots and elicited platelet-dependent fibrin-clot retraction ~ 60% as well as fresh platelets. RH platelets were similar in size to fresh and had less than 25% submicron particles as judged by electronic particle counting and flow cytometry scatter profiles. RH platelets were partially activated upon rehydration as judged by anti P-selectin and anti-LAMP-3 binding, yet GPIIb/IIIa remained in a resting conformation, as judged by a lack of PAC-1 binding. GPIIb/IIIa receptors were present as judged by the binding of complex-dependent (clone 5B12) and function-blocking (clone P2) antibodies. RH platelets also contained intact GPIbα as judged by binding of the function-blocking MoAb AN51. Function of GPIIb/IIIa and collagen receptors on RH platelets was further demonstrated as RH platelets adhered to immobilized fibrinogen and collagen in the absence of added agonists and in a dose-dependent manner. Moreover, RH platelets exhibited a two-fold increase in platelet procoagulant activity in the presence of thrombin receptor agonist peptide SFLLRN as judged by Annexin-V binding. Procoagulant and hemostatic activity was further demonstrated as RH platelets accelerated the clotting of recalcified whole thrombocytopenic blood in a dose-dependent manner similarly to fresh platelets. Lastly, RH platelets corrected the coagulopathy induced by contact pathway inhibition with aprotinin during the recalcification of citrated whole blood. The technology has been scaled to single donor platelet aphaeresis units, equivalent to a standard transfusion dose. Preclinical animal models of safety, efficacy, and circulation persistence are currently being evaluated. In summary, trehalose- stabilized lyophilized platelet derivatives contain numerous in vitro hemostatic properties and may offer an attractive alternative to fresh platelet transfusions when the latter are indicated yet unavailable.

scholarly journals Acaricidal activity of Furcraea foetida leaf extract against engorged female Rhipicephalus (Boophilus) microplus ticks

2021 ◽  
Vol 37 ◽  
pp. e37031
Author(s):  
Henrique Aparecido de Sousa Martins ◽  
Maria de Fatima Pereira ◽  
Enéas Ricardo Konzen ◽  
Gilvano Ebling Brondani ◽  
Wellington Ferreira Campos
Keyword(s):  
Crude Extract ◽  
Leaf Extract ◽  
Skin Lesions ◽  
Acaricidal Activity ◽  
Boophilus Microplus ◽  
Economic Damage ◽  
Attractive Alternative ◽  
Dependent Manner ◽  
Dose Dependent

The Rhipicephalus (Boophilus) microplus tick is a major concern for the livestock market worldwide, as it causes serious economic damage. Plant-derived acaricides are an attractive alternative to control this ectoparasite and limit the development of resistance. Therefore, the aim of this study was to evaluate the acaricidal activity of Furcraea foetida leaf extract against engorged female R. (B.) microplus ticks. Our in vitro bioassays showed that the crude extract of leaves from F. foetida caused hemorrhagic swelling and skin lesions in the ticks, and three days of treatment caused 100% mortality. Dose-response assay indicated that this toxicity effect was dose-dependent. Similar effects were observed when the crude extract from F. foetida leaves was denatured by boiling at 100°C. These results suggest that the toxicity of the leaf extract might be associated with thermostable biomolecules. Together, our results show for the first time that the crude extract of F. foetida leaves has acaricidal activity against engorged female R. (B.) microplus ticks and it acts in a dose-dependent manner.

scholarly journals Stimulation of cell proliferation in skeletal tissues of the rat by defined parathyroid hormone fragments

1991 ◽  
Vol 277 (3) ◽  
pp. 863-868 ◽  
Author(s):  
D Sömjen ◽  
K D Schlüter ◽  
E Wingender ◽  
H Mayer ◽  
A M Kaye
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Thymidine Incorporation ◽  
Specific Activity ◽  
Fold Increase ◽  
Dependent Manner ◽  
Equimolar Concentration ◽  
Dose Dependent

We have found, in previous studies in vitro using skeletal derived cell cultures, that mid-region fragments of human parathyroid hormone (hPTH) stimulate [3H]thymidine incorporation into DNA and increase the specific activity of the brain-type isoenzyme of creatine kinase (CK). These changes occurred without an increase in cyclic AMP formation which is linked to bone resorption. In this study, we found that the mid-region fragment hPTH-(28-48) stimulated CK activity in diaphysis, epiphysis and kidney in a time- and dose-dependent manner, parallel to the effects of the whole molecule bovine (b)PTH-(1-84) and the fully active fragment hPTH-(1-34). The increase caused by hPTH-(28-48) at a dose of 1.25 micrograms/rat was not less than the 2-fold increase caused by a roughly equimolar concentration bPTH-(1-84). A significant increase was reached at 1 h after intraperitoneal injection in all cases. All three sequences of PTH caused an increase in [3H]thymidine incorporation into DNA in diaphysis and epiphysis, but not in kidney, 24 h after injection. A fragment further towards the C-terminal, hPTH-(34-47), was inactive compared with an equimolar concentration of the fragment hPTH-(25-39), which stimulated both CK activity and DNA synthesis. These results in vivo are in line with previous findings in vitro; they provide further support for the suggestion that mid-region fragments of the PTH molecule could be used to induce bone formation without incurring the deleterious effect of bone resorption.

Activation of proteinase-activated receptor-2 in mesothelial cells induces pleural inflammation

2005 ◽  
Vol 288 (4) ◽  
pp. L734-L740 ◽  
Author(s):  
Y.C. Gary Lee ◽  
Darryl A. Knight ◽  
Kirk B. Lane ◽  
Dong Sheng Cheng ◽  
M. Audrey Koay ◽  
...  
Keyword(s):  
Pleural Fluid ◽  
Mesothelial Cell ◽  
Coagulation Factor ◽  
Fold Increase ◽  
Mesothelial Cells ◽  
Dependent Manner ◽  
Pleural Diseases ◽  
Dose Dependent

Pleural inflammation underlies many pleural diseases, but its pathogenesis remains unclear. Proteinase-activated receptor-2 (PAR2) is a novel seven-transmembrane receptor with immunoregulatory roles. We hypothesized that PAR2 is present on mesothelial cells and can induce pleural inflammation. PAR2 was detected by immunohistochemistry in all (19 parietal and 11 visceral) human pleural biopsies examined. In cultured murine mesothelial cells, a specific PAR2-activating peptide (SLIGRL-NH2) at 10, 100, and 1,000 μM stimulated a 3-, 42-, and 1,330-fold increase of macrophage inflammatory protein (MIP)-2 release relative to medium control, respectively ( P < 0.05 all) and a 2-, 32-, and 75-fold rise over the control peptide (LSIGRL-NH2, P < 0.05 all). A similar pattern was seen for TNF-α release. Known physiological activators of PAR2, tryptase, trypsin, and coagulation factor Xa, also stimulated dose-dependent MIP-2 release from mesothelial cells in vitro. Dexamethasone inhibited the PAR2-mediated MIP-2 release in a dose-dependent manner. In vivo, pleural fluid MIP-2 levels in C57BL/6 mice injected intrapleurally with SLIGRL-NH2 (10 mg/kg) were significantly higher than in mice injected with LSIGRL-NH2 or PBS (2,710 ± 165 vs. 880 ± 357 vs. 88 ± 46 pg/ml, respectively; P < 0.001). Pleural fluid neutrophil counts were higher in SLIGRL-NH2 group than in the LSIGRL-NH2 and PBS groups (by 40- and 26-fold, respectively; P < 0.05). This study establishes that activation of mesothelial cell PAR2 potently induces the release of inflammatory cytokines in vitro and neutrophil recruitment into the pleural cavity in vivo.

Development of a recombinant antithrombin variant as a potent antidote to fondaparinux and other heparin derivatives

Blood ◽  
2011 ◽  
Vol 117 (6) ◽  
pp. 2054-2060 ◽  
Author(s):  
Elsa P. Bianchini ◽  
Judicael Fazavana ◽  
Veronique Picard ◽  
Delphine Borgel
Keyword(s):  
Anticoagulant Activity ◽  
Fold Increase ◽  
Glycosylation Site ◽  
Dependent Manner ◽  
Heparin Derivatives ◽  
Dose Dependent ◽  
Heparin Derivative ◽  
In Vivo Administration

Abstract Heparin derivative-based therapy has evolved from unfractionated heparin (UFH) to low-molecular-weight heparins (LMWHs) and now fondaparinux, a synthetic pentasaccharide. Contrary to UFH or LMWHs, fondaparinux is not neutralized by protamine sulfate, and no antidote is available to counteract bleeding disorders associated with overdosing. To make the use of fondaparinux safer, we developed an antithrombin (AT) variant as a potent antidote to heparin derivatives. This variant (AT-N135Q-Pro394) combines 2 mutations: substitution of Asn135 by a Gln to remove a glycosylation site and increase affinity for heparins, and the insertion of a Pro between Arg393 and Ser394 to abolish its anticoagulant activity. As expected, AT-N135Q-Pro394 anticoagulant activity was almost abolished, and it exhibited a 3-fold increase in fondaparinux affinity. AT-N135Q-Pro394 was shown to reverse fondaparinux overdosing in vitro in a dose-dependent manner through a competitive process with plasma AT for fondaparinux binding. This antidote effect was also observed in vivo: administration of AT-N135Q-Pro394 in 2.5-fold molar excess versus plasma AT neutralized 86% of the anti-Xa activity within 5 minutes in mice treated with fondaparinux. These results clearly demonstrate that AT-N135Q-Pro394 can reverse the anticoagulant activity of fondaparinux and thus could be used as an antidote for this drug.

An in vitro Experimental Insight into the Osteoblast Responses to Vitamin D3 and Its Metabolites

Pharmacology ◽  
2018 ◽  
Vol 101 (5-6) ◽  
pp. 225-235 ◽  
Author(s):  
Dong Wang ◽  
Jiang Song ◽  
Huasong Ma
Keyword(s):  
Vitamin D3 ◽  
Osteoblast Differentiation ◽  
Cell Types ◽  
Cell Counting ◽  
Dependent Manner ◽  
Dihydroxyvitamin D3 ◽  
Osteogenic Markers ◽  
Polymerase Chain ◽  
Dose Dependent

Background: 25-hydroxyvitamin D3 (25[OH]VD3) has recently been found to be an active hormone. Its biological actions are also demonstrated in various cell types. However, the precise influences of vitamin D3 (VD3) and its metabolites (25[OH]VD3, 1α,25-dihydroxyvitamin D3 [1α,25-(OH)2VD3]) on the osteoblast differentiation remain largely unknown. In this work, we investigated the effects of VD3 and its metabolites in different concentrations on the early and later osteoblast differentiation and biomineralization. Methods: We first used quantitative real-time polymerase chain reaction (RT-qPCR) to evaluate the responsiveness of osteoblasts to VD3, 25(OH)VD3 or 1α,25-(OH)2VD3. We also evaluated the proliferation, differentiation and biomineralization of osteoblast at different time points via cell counting kit-8 assay and the analysis of osteogenic markers. Results: The experimental results confirmed that osteoblasts could be responsive to 25(OH)VD3 and 1α,25-(OH)2VD3 but could not directly metabolize VD3 and 25(OH)VD3. Only 200 nmol/L VD3 significantly promoted osteoblast proliferation, while 25(OH)VD3 and 1α,25-(OH)2VD3 did not show obvious actions. Moreover, the early osteogenic markers were increased by 25(OH)VD3 and 1α,25-(OH)2VD3 in a dose-dependent manner. More importantly, only 25(OH)VD3 had accelerated the gene and protein expressions of osteocalcin and the biomineralization level of osteoblasts. Conclusions: Our findings provide reliable evidence that 25(OH)VD3 at 100–200 nmol/L can induce the early and later osteoblast differentiation and biomineralization for clinical bone tissue engineering.

scholarly journals The Dual PI3Kδγ Inhibitor Duvelisib Potently Inhibits IL-6 Production and Cytokine Release Syndrome (CRS) While Maintaining CAR-T Function in Vitro and In Vivo

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 1-2
Author(s):  
Parmeshwar N Amatya ◽  
Alun J Carter ◽  
Julie K Ritchey ◽  
Jessica Niswonger ◽  
Matthew L Cooper ◽  
...  
Keyword(s):  
Surrogate Marker ◽  
Attractive Alternative ◽  
Dependent Manner ◽  
Cytokine Release ◽  
Cytokine Release Syndrome ◽  
Private Company ◽  
Car T ◽  
Dose Dependent

Despite remarkable clinical efficacy, CAR-T therapy has been limited by life-threatening toxicities in over 30% of patients (Maude, NEJM 2014 and Davila, SciTransMed 2014). Toxicities primarily manifest as Cytokine Release Syndrome (CRS) characterized by an early phase with fever, hypotension, and elevations of cytokines including IFNγ, GM-CSF, TNF, IL-10, and IL-6. Using a protein kinase inhibitor library containing 644 independent compounds, we aimed to identify compounds that could block CRS-related cytokine production without inhibiting CAR-T function. We identified, duvelisib (kindly provided by Verastem Oncology, Needham, MA), a novel and selective dual PI3K-δ,γ inhibitor as a potent inhibitor of CRS in vitro and in vivo without attenuating CAR-T function. Duvelisib (Copiktra) is approved for the treatment of relapsed/refractory CLL after 2 prior therapies and follicular lymphoma after 2 prior systemic therapies; the latter gained accelerated approval status based on overall response rate and continued approval may be contingent on confirmatory trials. To assess the ability of duvelisib to inhibit CAR-T mediated CRS, we performed an in vitro CRS assay (Singh, Cytotherapy, 2017). CART19 (19-28BBζ, 25,000 cells), Ramos (CD19+, 50,000 cells), and immature dendritic cells (iDC, 2,500 cells) were co-cultured in a 96 well plate for 48hrs in the presence of varying concentrations of duvelisib (0.3nM-1000nM). Secreted IL-6, a surrogate marker of CRS, was determined using a human IL-6 ELISA (R&D Systems). Duvelisib reduced IL-6 levels in a dose-dependent manner with 30nM duvelisib reducing IL-6 secretion more than 10-fold (Fig 1a). To confirm that duvelisib did not inhibit CAR-T function, we performed in vitro killing assays, in which CAR-T efficacy was determined using BLI imaging of luciferase labeled CD19+ Ramos targets. At clinically relevant therapeutic doses (C max of 200 to 500nM) of duvelisib, there was no effect on CAR-T function in vitro. Treatment with 10nM duvelisib resulted in a statistically insignificant ~20% reduction of CART19 efficacy (p&gt;0.05) (Fig 1b). Of interest, although selective inhibitors of either or PI3Kδ (GSK2292767) or PI3Kγ (IPI549) had modest effects on blocking CAR-T induced IL-6 production in this in vitro model, the effect of combining both inhibitors had a more dramatic effect similar to the dual PI3K-δ,γ inhibitor, duvelisib. Next we assessed the ability of duvelisib to block IL-6 secretion in vivo using a fully immunocompetent murine model of CRS. Six-week old BALB/c mice were injected with the mitogenic anti-CD3ε antibody, 145-2C11 (10 µg/mouse). Duvelisib (450µg/mouse) was administered daily intraperitoneally (I.P), with the first dose of duvelisib injected 24 hours prior to injection of 145-2C11. Plasma IL-6 levels were determined using a mouse IL-6 ELISA (R&D Systems). Injection of 145-2C11 acutely elevated plasma IL-6 &gt;32 fold relative to non-treated controls (4hrs; Control 34.4 pg/mL versus vs. 145-2C11 1088±99.6 pg/mL). Duvelisib significantly reduced mean plasma IL-6 &gt;54% at 4hrs (Vehicle 1088±99.6 pg/ml vs duvelisib 492±99.6 pg/ml, p≤ 0.01) and &gt;78% at 24hrs (Vehicle 220±101 pg/ml vs. duvelisib 49.3±16.1, p≤ 0.01) (Fig 1c) consistent with the effect of duvelisib in our in vitro CAR-T-induced CRS model described above. These studies demonstrate that duvelisib can inhibit CAR-T induced IL-6 production from iDC while having no inhibitory effect on CAR-T. Experiments are currently in progress to further characterize PI3K-δ,γ inhibition in humanized mouse models of CRS and CAR-T efficacy. Our preclinical data suggest that dual PI3K-δ,γ inhibition with duvelisib may represent an attractive alternative to IL-6 receptor antagonists, such as tocilizumab, for the treatment of CAR-T-associated cytokine release syndrome in the clinic which warrants further clinical evaluation. Figure 1. Dose dependent effect of duvelisib on IL-6 secretion in co-culture of CART19, Ramosluc, and iDC after 48 hours (a) Dose dependent inhibition of CART19 mediated cytotoxicity using duvelisib (b) Duvelisib effectively lowers IL-6 plasma level in an immunocompetent BALB/cJ mouse model of CRS (c). (** p≤ 0.01 and ns p&gt;0.05). Figure 1 Disclosures Cooper: Wugen: Consultancy, Current equity holder in private company, Patents & Royalties. Pachter:Verastem Therapeutics: Current Employment. DiPersio:Magenta Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Immunization of male rabbits with sheep luteal receptor to LH results in production of antibodies exhibiting hormone-agonistic and -antagonistic activities

1996 ◽  
Vol 150 (3) ◽  
pp. 431-443 ◽  
Author(s):  
M Jeyakumar ◽  
N R Moudgal
Keyword(s):  
Leydig Cells ◽  
Serum Testosterone ◽  
Fold Increase ◽  
Dependent Manner ◽  
Primary Immunization ◽  
Testosterone Production ◽  
Dose Dependent ◽  
Receptor Antibodies

Abstract Antibodies to LH/chorionic gonadotrophin receptor (LH/CG-R; molecular weight 67 000), isolated in a homogenous state (established by SDS-PAGE and ligand blotting) from sheep luteal membrane using human CG (hCG)–Sepharose affinity chromatography, were raised in three adult male rabbits (R-I, R-II and R-III). Each of the rabbits received 20–30 μg of the purified receptor in Freund's complete adjuvant at a time. Primary immunization was followed by booster injection at intervals. Production of receptor antibodies was monitored by (1) determining the dilution of the serum (IgG fraction) that could specifically bind 50% of 125I-LH/CG-R added and (2) analysing sera for any change in testosterone levels. Following primary immunization and the first booster, all three rabbits exhibited a 2·5- to 6·0-fold increase in serum testosterone over basal levels and this effect was spread over a period of time (∼40 days) coinciding with the rise and fall of receptor antibodies. The maximal antibody titre (ED50) produced at this time ranged from 1:350 to 1:100 to below detectable limits for R-I, R-II and R-III respectively. Subsequent immunizations followed by the second booster resulted in a substantial increase in anti-body titre (ED50 of 1:5000) in R-I, but this was not accompanied by any change in serum testosterone over preimmune levels, suggesting that with the progress of immunization the character of the antibody produced had also changed. Two pools of antisera from R-I collected 10 days following the booster (at day 70 (bleed I) and day 290 (bleed II)) were used in further experiments. IgG isolated from bleed I but not from bleed II antiserum showed a dose-dependent stimulation of testosterone production by mouse Leydig cells in vitro, thus confirming the in vivo hormone-mimicking activity of antibodies generated during the early immunization phase. The IgG fractions from both bleeds were, however, capable of inhibiting (1) 125I-hCG binding to crude sheep luteal membrane (EC50 of 1:70 and 1:350 for bleed I and II antisera respectively) and (2) ovine LH-stimulated testosterone production by mouse Leydig cells in vitro, indicating the presence of antagonistic antibodies irrespective of the period of time during which the rabbits were immunized. The fact that bleed I-stimulated testosterone production could be inhibited in a dose-dependent manner by the addition of IgG from bleed II to the mouse Leydig cell in vitro assay system showed that the agonistic activity is intrinsic to the bleed I antibody. The receptor antibody (bleed II) was also capable of blocking LH action in vivo, as rabbits passively (for 24 h with LH/CG-R antiserum) as well as actively (for 430 days) immunized against LH/CG-R failed to respond to a bolus injection of LH (50 μg). At no time, however, was the serum testosterone reduced below the basal level. This study clearly shows that, unlike with LH antibody, attempts to achieve an LH deficiency effect in vivo by resorting to immunization with holo LH receptor is difficult, as receptor antibodies exhibit both hormone-mimicking (agonistic) as well as hormone-blocking (antagonistic) activities. Journal of Endocrinology (1996) 150, 431–443

scholarly journals RETRACTED ARTICLE: Titanium particles damage osteocytes and inhibit osteoblast differentiation

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Li Chen ◽  
Ziyue Wang ◽  
Wei Xu ◽  
Qirong Dong
Keyword(s):  
Cell Viability ◽  
Osteoblast Differentiation ◽  
Cell Counting ◽  
Cell Contact ◽  
Dependent Manner ◽  
Retracted Article ◽  
Ti Particles ◽  
Dose Dependent Decrease ◽  
Dose Dependent

Abstract Purposes to study the effect of titanium particles on MLO-Y4 and the effects of osteocytes alterations on osteoblasts. Methods cultured MLO-Y4 osteocytes were exposed to different concentrations of titanium (Ti) particles, cell viability was measured using the Cell Counting Kit-8 (CCK-8) assay, apoptosis of MLO-Y4 cells was evaluated by flow cytometry, Real-time PCR quantification of mRNA expression of SOST, at the same time with Western Blot detection sclerosteosis protein expression levels.MC3T3-E1 cells culture with MLO-Y4 cells exposed to different concentrations of titanium (Ti) particles in vitro, in order to detection of osteoblast osteogenetic activity. Results Our results showed that Ti particles inhibited cell viability of MLO-Y4 osteocytes in a dose-dependent manner. Incubation with Ti particles caused apoptosis of MLO-Y4cells.Treatment with Ti particles significantly increased expression of the osteocytic marker SOST/sclerostin. Furthermore, treatment of MLO-Y4 cells with Ti particles produced a dose-dependent decrease in ALP activity and decreased mineralization of MC3T3-E1 cells through direct cell-cell contact. Conclusions Titanium particles damage osteocytes and inhibit osteoblast differentiation.

Increased Protein Synthesis by Human Platelets during Phagocytosis of Latex Particles in Vitro

1976 ◽  
Vol 35 (02) ◽  
pp. 350-357 ◽  
Author(s):  
Hana Bessler ◽  
Galila Agam ◽  
Meir Djaldetti
Keyword(s):  
Protein Synthesis ◽  
Fold Increase ◽  
Human Platelets ◽  
Polystyrene Latex ◽  
Latex Particles ◽  
The Third ◽  
Platelet Protein ◽  
Dose Dependent ◽  
Phagocytotic Activity

SummaryA three-fold increase of protein synthesis by human platelets during in vitro phagocytosis of polystyrene latex particles was detected. During the first two hours of incubation, the percentage of phagocytizing platelets and the number of latex particles per platelet increased; by the end of the third hour, the first parameter remained stable, while the number of latex particles per cell had decreased.Vincristine (20 μg/ml of cell suspension) inhibited platelet protein synthesis. This effect was both time- and dose-dependent. The drug also caused a decrease in the number of phagocytizing cells, as well as in their phagocytotic activity.

Oxygenation of 18-hydroxycorticosterone as the final reaction for aldosterone biosynthesis

1984 ◽  
Vol 107 (3) ◽  
pp. 395-400 ◽  
Author(s):  
Itaru Kojima ◽  
Etsuro Ogata ◽  
Hiroshi Inano ◽  
Bun-ichi Tamaoki
Keyword(s):  
Carbon Monoxide ◽  
Hydroxysteroid Dehydrogenase ◽  
Dependent Manner ◽  
In Vitro Production ◽  
Mitochondrial Preparation ◽  
Final Reaction ◽  
Vitro Production ◽  
Dose Dependent ◽  
Cytochrome P 450

Abstract. Incubation of 18-hydroxycorticosterone with the sonicated mitochondrial preparation of bovine adrenal glomerulosa tissue leads to the production of aldosterone, as measured by radioimmunoassay. The in vitro production of aldosterone from 18-hydroxycorticosterone requires both molecular oxygen and NADPH, and is inhibited by carbon monoxide. Cytochrome P-450 inhibitors such as metyrapone, SU 8000. SU 10603, SKF 525A, amphenone B and spironolactone decrease the biosynthesis of aldosterone from 18-hydroxycorticosterone. These results support the conclusion that the final reaction in aldosterone synthesis from 18-hydroxycorticosterone is catalyzed by an oxygenase, but not by 18-hydroxysteroid dehydrogenase. By the same preparation, the production of [3H]aldosterone but not [3H]18-hydroxycorticosterone from [1,2-3H ]corticosterone is decreased in a dose-dependent manner by addition of non-radioactive 18-hydroxycorticosterone.

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