scholarly journals The uptake of 3H-labelled monodeoxyfluoro-myo-inositols into thymocytes and their incorporation into phospholipid in permeabilized cells

1993 ◽  
Vol 291 (2) ◽  
pp. 553-560 ◽  
Author(s):  
J Offer ◽  
J C Metcalfe ◽  
G A Smith
Keyword(s):  
Cellular Responses ◽  
Effective Inhibitor ◽  
Permeabilized Cells ◽  
Label Technique ◽  
Competitive Inhibitors ◽  
Phosphatidylinositol Synthase ◽  
Potential Inhibitors ◽  
Dual Label ◽  
Inositol Uptake

Monodeoxyfluoro-myo-inositols were applied to electropermeabilized and intact thymocyte preparations to study their metabolism and uptake in order to investigate their suitability as potential inhibitors of phosphoinositide-mediated cellular responses. Only three of the monodeoxyfluoro-myo-inositols were incorporated into the phospholipids of thymocytes: 1D-3-deoxy-3-fluoro-myo-inositol, 5-deoxy-5-fluoro-myo-inositol and 1D-6-deoxy-6-fluoro-myo-inositol, all of which were weaker substrates for phosphatidylinositol synthase than was myo-inositol. The 3-, 5- and 6-fluoro analogues also behaved as competitive inhibitors, with K1 values of 350 +/- 5 microM, 350 +/- 5 microM and 2.9 +/- 2 mM respectively, compared with a Km for myo-inositol of 31 +/- 4 microM. When incubated with electropermeabilized thymocyte preparations, these three analogues of myo-inositol all formed phospholipids with chromatographic properties which corresponded to those of substituted phosphatidylinositol and phosphatidylinositol monophosphate. The uptake of myo-inositol and of the monodeoxyfluoro-myo-inositols into intact thymocytes was studied by a dual-label technique. All the monodeoxyfluoro-myo-inositols were taken up to some extent, but only 2-deoxy-2-fluoro-myo-inositol and 1D-3-deoxy-3-fluoro-myo-inositol were actively concentrated. The monodeoxyfluoro-myo-inositols were also assayed for their ability to inhibit the uptake of myo-inositol into cells. Both 2-deoxy-2-fluoro-myo-inositol and 1D-3-deoxy-3-fluoro-myo-inositol were effective inhibitors of myo-inositol uptake. Furthermore, 1D-1-deoxy-1-fluoro-myo-inositol, which was not taken up actively, was an effective inhibitor of myo-inositol uptake. The three effective inhibitors all showed Ki values of approximately 150 microM, close to the apparent Km for inositol uptake of 180 microM, and the 4-, 5- and 6-fluoro analogues had Ki values in excess of 10 mM.

scholarly journals Structural Analogues of Lanosterol from Marine Organisms of the Class Asteroidea as Potential Inhibitors of Human and Candida albicans Lanosterol 14α-demethylases

2017 ◽  
Vol 12 (12) ◽  
pp. 1934578X1701201 ◽  
Author(s):  
Leonid A. Kaluzhskiy ◽  
Tatsiana V. Shkel ◽  
Natalia V. Ivanchina ◽  
Alla A. Kicha ◽  
Irina P. Grabovec ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Cytochromes P450 ◽  
Resonance Method ◽  
Spectrophotometric Titration ◽  
Marine Organisms ◽  
Lead Compounds ◽  
Selective Ligands ◽  
Competitive Inhibitors ◽  
Different Types ◽  
Potential Inhibitors

Lanosterol 14α-demethylases (hemoproteins of the cytochrome P450(51) family) are involved in biosynthesis of different membrane sterols, including animal cholesterol, fungal ergosterol and C24-modified plant and protozoa sterols. In this study we have investigated 10 structural analogs of lanosterol isolated from echinoderms belonging to the class Asteroidea as potential ligands (competitive inhibitors) of human and Candida albicans cytochromes P450(51). The study was performed using the surface plasmon resonance method, spectrophotometric titration and enzyme assay. Among the compounds tested we found several selective ligands for human and Candida albicans cytochromes. Between selective ligands of the human lanosterol 14α-demethylase we found two novel inhibitors of this enzyme: henricioside H1 and levisculoside G from Henricia derjugini. With due consideration of obtained data, we conclude that marine organisms from the class Asteroidea can be a valuable source of new lead compounds for creation of selective inhibitors of cytochromes P450(51) family with less side effects due to their selective action on these enzymes in different types of organisms.

A new dual-label technique for platelet survival studies with the use of111indium and114mindium tropolonate

1991 ◽  
Vol 78 (2) ◽  
pp. 236-241 ◽  
Author(s):  
R. A. de Vries ◽  
M. de Bruin ◽  
S. J. Oldenburg ◽  
A. Zwiers ◽  
J. J. M. Marx ◽  
...  
Keyword(s):  
Label Technique ◽  
Platelet Survival ◽  
Survival Studies ◽  
Dual Label

scholarly journals Relevance of pretransfusion incubation of platelets at 37 degrees C

Blood ◽  
1992 ◽  
Vol 80 (6) ◽  
pp. 1599-1602
Author(s):  
RA de Vries ◽  
JG Gerritsen ◽  
M de Bruin ◽  
JJ Marx ◽  
HC Hart ◽  
...  
Keyword(s):  
Beneficial Effect ◽  
Mean Platelet Volume ◽  
Healthy Subjects ◽  
The Other ◽  
Platelet Concentrates ◽  
Platelet Volume ◽  
Label Technique ◽  
The Mean ◽  
Initial Recovery ◽  
Dual Label

The effect of pretransfusion incubation of platelets at 37 degrees C was assessed because of the controversial reports about its relevance. A dual-label technique (111indium and 114mindium) was applied in 10 healthy subjects receiving warmed and unwarmed autologous platelets simultaneously. Fresh platelet concentrates were infused into five subjects, whereas the other five subjects received stored platelet concentrates. The mean platelet volume decreased in all platelet concentrates during incubation, reflecting the restoration of the discoid shape of the platelets. The mean decrease was 0.35 fL (P = .003). However, the initial recovery and the mean platelet life-span were not improved by this procedure. It was concluded that there is no evidence that brief warming of platelets has any beneficial effect on platelet viability in healthy volunteers.

scholarly journals Malate exchange between the cytosol and mitochondria

1973 ◽  
Vol 132 (2) ◽  
pp. 349-352 ◽  
Author(s):  
Robert Rognstad ◽  
Joseph Katz
Keyword(s):  
Transport System ◽  
Isotopic Exchange ◽  
Phosphate Transport ◽  
Effective Inhibitor ◽  
Intact Cells ◽  
Isolated Mitochondria ◽  
Potential Inhibitors

1. By comparing the relative isotopic yields in glucose and CO2 from precursors of mitochondrial and cytosolic malate, it is evident that the rate of isotopic exchange between these compartments is rapid. 2. A variety of potential inhibitors of malate exchange were tested, but no specific and effective inhibitor of the isotopic exchange has been found. 3. Compounds such as n-butylmalonate and p-iodobenzylmalonate, which have been used as inhibitors of the malate–phosphate transport system in isolated mitochondria, do not appear to be sufficiently specific to be useful in studies with intact cells.

scholarly journals Guanine nucleotides stimulate polyphosphoinositide phosphodiesterase and exocytotic secretion from HL60 cells permeabilized with streptolysin O

1988 ◽  
Vol 250 (2) ◽  
pp. 375-382 ◽  
Author(s):  
J Stutchfield ◽  
S Cockcroft
Keyword(s):  
Rank Order ◽  
Guanine Nucleotides ◽  
Hl60 Cell ◽  
Maximal Response ◽  
Permeabilized Cells ◽  
Kinase C ◽  
Streptolysin O ◽  
Competitive Inhibitors ◽  
In Series ◽  
Gamma S

The non-differentiated HL60 cell can be stimulated to secrete when Ca2+ and guanosine 5′-[gamma-thio]-triphosphate (GTP gamma S) are introduced into streptolysin-O-permeabilized cells. Secretion is accompanied by activation of polyphosphoinositide phosphodiesterase (PPI-pde). Both responses show a concentration-dependence on Ca2+ between pCa 8 and pCa 5. The half-maximal requirements for Ca2+ for PPI-pde activation and secretion are pCa 6.4 +/- 0.1 and pCa 6.2 +/- 0.2 respectively. The rank order of potency of the GTP analogues to stimulate PPI-pde activation and secretion is similar; GTP gamma S greater than guanosine 5′-[beta gamma-imido]-triphosphate greater than guanosine 5′-[beta gamma-methylene]triphosphate greater than XTP approximately equal to ITP, but the maximal response achieved by each compound compared with GTP gamma S is much greater for secretion than for PPI-pde activation. A dissociation of the two responses is obtained with 10 mM-XTP and -ITP; secretion is always observed but not inositol trisphosphate formation at this concentration. GTP, dGTP, UTP and CTP are inactive for both secretion and PPI-pde activation. Both GDP and dGDP are competitive inhibitors of both GTP gamma S-induced secretion and PPI-pde activation. Phorbol 12-myristate 13-acetate could not fully substitute for GTP gamma S in stimulating secretion, suggesting that the effect of GTP gamma S cannot result simply from the generation of diacylglycerol. In the absence of MgATP, secretion and PPI-pde activation is still evident, albeit at a reduced level. This also supports the hypothesis that protein kinase C-dependent phosphorylation is not essential for secretion. The effect of MgATP is to enhance secretion, and to reduce both the Ca2+ and GTP gamma S requirement for secretion. In conclusion, two roles for guanine nucleotides can be identified; one for activating PPI-pde (GP) and the other for activating exocytosis (GE), acting in series.

Synthesis and evaluation of 3-modified 1D-myo-inositols as inhibitors and substrates of phosphatidylinositol synthase and inhibitors of myo-inositol uptake by cells

1993 ◽  
Vol 36 (23) ◽  
pp. 3628-3635 ◽  
Author(s):  
Stephen C. Johnson ◽  
Jean Dahl ◽  
Tzenge Lien Shih ◽  
David J. A. Schedler ◽  
Laurens Anderson ◽  
...  
Keyword(s):  
Phosphatidylinositol Synthase ◽  
Inositol Uptake

scholarly journals Relevance of pretransfusion incubation of platelets at 37 degrees C

Blood ◽  
1992 ◽  
Vol 80 (6) ◽  
pp. 1599-1602 ◽  
Author(s):  
RA de Vries ◽  
JG Gerritsen ◽  
M de Bruin ◽  
JJ Marx ◽  
HC Hart ◽  
...  
Keyword(s):  
Beneficial Effect ◽  
Mean Platelet Volume ◽  
Healthy Subjects ◽  
The Other ◽  
Platelet Concentrates ◽  
Platelet Volume ◽  
Label Technique ◽  
The Mean ◽  
Initial Recovery ◽  
Dual Label

Abstract The effect of pretransfusion incubation of platelets at 37 degrees C was assessed because of the controversial reports about its relevance. A dual-label technique (111indium and 114mindium) was applied in 10 healthy subjects receiving warmed and unwarmed autologous platelets simultaneously. Fresh platelet concentrates were infused into five subjects, whereas the other five subjects received stored platelet concentrates. The mean platelet volume decreased in all platelet concentrates during incubation, reflecting the restoration of the discoid shape of the platelets. The mean decrease was 0.35 fL (P = .003). However, the initial recovery and the mean platelet life-span were not improved by this procedure. It was concluded that there is no evidence that brief warming of platelets has any beneficial effect on platelet viability in healthy volunteers.

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