help button home button Endocrine Society JCEM
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ferretti, G.
Right arrow Articles by Mazzanti, L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ferretti, G.
Right arrow Articles by Mazzanti, L.
The Journal of Clinical Endocrinology & Metabolism Vol. 87, No. 5 2180-2184
Copyright © 2002 by The Endocrine Society

Other Original Articles

Glycated Low Density Lipoproteins Modify Platelet Properties: A Compositional and Functional Study

G. Ferretti, R. A. Rabini, T. Bacchetti, A. Vignini, E. Salvolini, F. Ravaglia, G. Curatola and L. Mazzanti

Institute of Biochemistry, University of Ancona School of Medicine; Department of Diabetology, INRCA Hospital (R.A.R.); and Department of Clinical Chemistry, Torrette Hospital (F.R.), 60131 Ancona, Italy

Address all correspondence and requests for reprints to: Prof. Laura Mazzanti, Institute of Biochemistry, University of Ancona, Via P. Ranieri 65, 60131 Ancona, Italy. E-mail: . mazzanti{at}popcsi.unian.it

Abstract

The interaction between low density lipoproteins (LDL) and platelets might play a central role in the development of atherosclerosis in diabetes. The aim of the present study was to investigate whether the glycation of LDL is associated with modifications of their physico-chemical and functional properties and to study the action of glycated LDL (glycLDL) on platelets. LDL and platelets were isolated from 15 healthy subjects. The content of thiobarbituric acid-reactive substances and the generalized polarization of the fluorescent probe Laurdan were determined in LDL glycated in vitro. Platelets were incubated with native LDL, GlycLDL, and minimally oxidized LDL, and the following parameters were evaluated: platelet aggregation, nitric oxide production, intracellular Ca2+ concentrations, Na+/K+-adenosine triphosphatase (Na+/K+-ATPase), and Ca2+-ATPase activities. GlycLDL showed increased thiobarbituric acid-reactive substance levels, a red shift of the Laurdan emission maximum, and a decrease in generalized polarization, indicating a higher polarity and a reduced molecular order compared with native LDL. GlycLDL caused a significant increase in platelet nitric oxide production, intracellular Ca2+ concentration, and aggregating response to ADP; an inhibition of the platelet membrane Na+/K+-ATPase activity; and a stimulation of Ca2+-ATPase activity. Minimally oxidized LDL did not cause statistically significant changes in the parameters studied. The present work demonstrates that glycation induces compositional and structural changes in LDL and suggests that an altered interaction between glycLDL and platelets might play a role in the vascular complications of diabetes.

RECENT DATA SUGGEST that the interaction between low density lipoproteins (LDL) and circulating cells, such as platelets, might play a central role in the development of atherosclerosis. In fact, it has been demonstrated that oxidized LDL (oxLDL) increase platelet aggregation by means of an enhanced sensitivity to agonists and a reduction of platelet nitric oxide (NO) synthase (NOS) expression and activity (1). Activated platelets, in turn, secrete a protein-like factor that stimulates the uptake of oxLDL by macrophages (2).

Hyperglycemia induces an increase in nonenzymatically glycated products, which are involved in the pathogenesis of diabetic complications. Nonenzymatic glycation of plasma LDL might be involved in the development of the late complications of diabetes, increasing their susceptibility to oxidative stress (3). Moreover, glycated LDL (glycLDL) show several functional alterations, with an enhanced uptake by macrophages (4) and chemotaxis of human monocytes (5).

Our group recently demonstrated that LDL obtained from diabetic patients enhance platelet aggregation in response to ADP compared with platelets incubated in buffer and with cells incubated with control LDL and suggested that this effect might be caused by an increase in cytosolic Ca2+ concentrations and a reduction in NOS activity and platelet membrane Na+/K+-adenosine triphosphatase (Na+/K+-ATPase) activity (6). We hypothesized that a difference in glycation of LDL obtained from healthy and diabetic subjects might be involved in this LDL effect, but the role of LDL glycation in determining this platelet dysfunction was not investigated in our previous work (6).

To elucidate the molecular mechanisms at the basis of these effects of diabetic LDL on platelets, we investigated whether the glycation of LDL is associated with modifications of their physico-chemical and functional properties, and we studied the action of LDL obtained from healthy subjects and subsequently glycated in vitro (glycLDL) on platelets derived from the same subjects. Minimally oxidized LDL (moxLDL) with levels of peroxidation products similar to those present in glycLDL were also used for incubation experiments to differentiate the specific effects of glycation from the general effects of oxidation.

Subjects and Methods

The study was performed on 15 healthy male volunteers. The clinical characteristics of subjects from whom LDL were obtained are shown in Table 1Go. A glucose tolerance test was previously performed to exclude the presence of diabetes or impaired glucose tolerance. Each subject gave informed consent before the investigation. The study was performed in accordance with the principles of the Declaration of Helsinki as revised in 1996.


View this table:
[in this window]
[in a new window]
  		Table 1. Clinical characteristics of subjects from whom LDLs were obtained

 
Blood was drawn in the fasting state for the determination of glycemia and hemoglobin A1c levels and was used for the isolation of LDL and platelets.

Data are expressed as the mean ± SD. Statistical analysis was carried out using a t test for paired data. The linear regression analysis was used to study the relations between the parameters evaluated in LDL.

Lipoprotein studies

Lipoprotein isolation, nonenzymatic glycation of LDL, and preparation of minimally oxidized LDL. LDL (density, 1.025–1.063 g/ml) were isolated from human plasma and prepared by single spin vertical ultracentrifugation as described by Chung et al. (1). After dialysis, LDL were resuspended in phosphate buffer and incubated in the presence of different concentrations of glucose (0, 50, and 100 mM) for different times (0, 24, 48, and 72 h) (7). The antioxidant butylated hydroxytoluene (25 µM) was added to the solution to reduce the oxidation derived from processes independent from glycation.

MoxLDL were prepared from native LDL by Cu2+-triggered oxidation as described by Weidtmann et al. (8). Butylated hydroxytoluene (25 µM) was added to obtain a slight lipid peroxidation similar to that observed in the glycLDL used for the incubation experiments [thiobarbituric acid-reactive substances (TBARS), 0.29 ± 0.05 nmol/100 µg protein].

Study of lipid peroxidation. The extent of lipid peroxidation of LDL was evaluated by measuring TBARS according to the method of Yagi (9). Results are expressed as nanomoles of malondialdehyde per 100 µg protein. Proteins were measured by the method of Lowry (10).

Fluorescence measurements. 2-Dimethylamino-(6-lauroyl)-naphtalene (Laurdan) was purchased from Molecular Probes, Inc. (Eugene, OR). The incorporation of Laurdan with LDL was carried out incubating 100 µg LDL protein with 2 µl Laurdan (stock solution in ethanol) at a final concentration of 1 µM for 30 min at room temperature (24 C) in agreement with our previous studies (11). Laurdan generalized polarization (Gp340; {lambda} ex = 340 nm) was calculated using the method reported by Parasassi et al. (12) according to the equation: Gp = (IB - IR).(IB + IR), where IB and IR are the emission intensities at the blue (440 nm) and red (490 nm) edges of the emission spectrum and correspond to the fluorescent emission maxima in the gel and liquid crystalline phases, respectively.

Incubation experiments

Platelet isolation and LDL incubation. Platelets were isolated from peripheral venous blood mixed with anticoagulant citrate dextrose (36 ml citric acid, 5 mmol/liter KCl, 90 mmol/liter NaCl, 5 mmol/liter glucose, and 10 mmol/liter EDTA, pH 6.8) according to the method of Rao (13) and immediately used for the incubation experiments.

Platelets were incubated for 3 h at 37 C with buffer, native LDL (nLDL), glycLDL, or moxLDL (100 µg LDL protein/ml). Before and after incubation the following parameters were evaluated: platelet aggregation, NO production, intracellular Ca2+ concentrations ([Ca2+]i), and Na+/K+-ATPase and Ca2+-ATPase activities. For incubation experiments we chose LDL glycated for 48 h.

Platelet aggregation. The platelet aggregation studies were carried out according to Born’s method (14) using the photometric system Packs-4 (Helena Laboratories, Beaumont, TX). The aggregating response to ADP was evaluated as the reduction of light absorption and was quantified as maximal aggregation (percentage) using the formula reported by Weiss and Rogers (15).

NO measurements. NO released by the platelets was directly measured in the platelet-rich plasma using an isolated NO meter and its associated probe (IsoNO Mk-II, World Precision Instruments, Sarasota, FL) equipped with the Duo.18 Data Acquisition System, as recently described by Chakravarthy et al. (16). NO gas diffuses through to the probe tip and is oxidized at the working electrode, resulting in an electrical current proportional to its concentration. NO production was determined in platelet-rich plasma after the addition of 100 µM L-arginine, which induced a rapid increase in NO release measurable 30 sec after stimulation, with a peak between 60 and 90 sec.

Intracellular Ca2+ concentrations [Ca2+]i. [Ca2+]i was measured in platelets using the fluorescent probe fura-2/AM as previously described (17). Determinations were performed in an LS 50B spectrofluorometer (Perkin-Elmer Corp., Palo Alto, CA) at 37 C according to the method of Rao (13), and calibrations were performed as described by Grynkiewicz et al. (18).

Na+/K+-ATPase assay. Na+/K+-activated Mg2+-dependent ATPase activity was determined in platelet plasma membranes obtained by the method of Enouf (19). ATPase activity was assayed by incubating membranes at 37 C in the reaction buffer containing MgCl2 (5 mM), NaCl (140 mM), and KCl (14 mM) in 40 mM Tris-HCl, pH 7.7, as previously described (17). The ATPase reaction was started by the addition of 3 mmol/liter Na2ATP. Inorganic phosphate (Pi) hydrolyzed from this reaction was measured by the method of Fiske and Subbarow (20). The ATPase activity assayed in the presence of 10 mM ouabain was subtracted from the total Mg2+-dependent ATPase activity to calculate the activity of Na+/K+-ATPase (21). The protein concentration was determined as described by Lowry et al. (10) using serum albumin as a standard.

Ca2+-ATPase activity. Ca2+-ATPase activity was determined in platelet plasma membranes according to the method described by Davis et al. (22) by measuring the Pi hydrolyzed from 1 mmol/liter Na2ATP at 37 C in the presence and absence of 0.15 mmol/liter Ca2+. ATPase determined in the absence of Ca2+ was subtracted from total ATPase activity to calculate Ca2+-ATPase activity.

Results

The levels of TBARS in LDL incubated in the presence of glucose were higher than those in LDL incubated without glucose (Fig. 1Go). The effect of glucose on lipoprotein oxidation was both concentration and time dependent. The highest increase in TBARS was found at 72 h of incubation with 100 mmol glucose (Fig. 1Go).



View larger version (20K):
[in this window]
[in a new window]
  		Figure 1. Levels of TBARS in nLDL and LDL incubated for different hours in the absence and presence of glucose. The mean ± SD are shown.

 
The position of the emission maximum of Laurdan incorporated in untreated LDL was 423.7 ± 0.4 nm, as previously observed (11). In LDL incubated with glucose the position of the emission maximum was red-shifted with respect to LDL incubated in the absence of glucose (Fig. 2Go). The red shift indicates an increase in polarity in the microenvironment of Laurdan incorporated in LDL incubated with glucose.



View larger version (19K):
[in this window]
[in a new window]
  		Figure 2. Emission maximum of Laurdan incorporated in nLDL and LDL incubated for different numbers of hours in the absence or presence of glucose. The mean ± SD are shown.

 
In untreated LDL the Laurdan generalized polarization (Gp) value was 0.555 ± 0.020. In LDL incubated with glucose for different times the Gp value was decreased with respect to LDL incubated in the absence of glucose (Fig. 3Go). The decrease occurred to the greatest extent after 72 h of incubation and indicates a decrease in molecular order in glycLDL with respect to untreated samples. A positive correlation (r = 0.89; P < 0.01) was found between TBARS levels and the position of the emission maximum, whereas a negative correlation (r = -0.71; P < 0.01) was found between Gp and TBARS.



View larger version (23K):
[in this window]
[in a new window]
  		Figure 3. Gp value in nLDL and LDL incubated for different numbers of hours in the absence or presence of glucose. The mean ± SD are shown.

 
The incubation of platelets with nLDL or moxLDL did not cause any significant change in the parameters studied in comparison with both platelets in the basal state and platelets incubated in buffer (Table 2Go). On the contrary, glycLDL caused a significant increase in platelet NO production, an inhibition to about 25% of platelet membrane Na+/K+-ATPase activity, and a significant stimulation of Ca2+-ATPase activity compared with platelets incubated with buffer and nLDL (Table 2Go and Figs. 4–6GoGoGo). Cytoplasmic Ca2+ concentrations were significantly higher after incubation with glycLDL than in the presence of buffer and nLDL (Table 2Go and Fig. 7Go). The aggregating response to ADP quantified as maximal aggregation (percentage) was significantly increased in platelets incubated with glycLDL compared with cells incubated with nLDL (platelets and nLDL, 7.70 ± 1.20%; platelets and glycLDL, 10.75 ± 1.70%; P < 0.01), whereas it was not significantly changed in the presence of moxLDL (8.2 ± 1.4%).


View this table:
[in this window]
[in a new window]
  		Table 2. NO production, Na+/K+-ATPase activity, Ca2+-ATPase activity, and [Ca2+]i in platelets incubated with buffer (Plts), native LDL (nLDL), glycated LDL (GlycLDL), and minimally oxidized LDL (Mox-LDL)

 


View larger version (14K):
[in this window]
[in a new window]
  		Figure 4. NO production in platelets incubated with buffer (Plts), nLDL, and glycLDL. The mean ± SD are shown.

 


View larger version (18K):
[in this window]
[in a new window]
  		Figure 5. Na+/K+-ATPase activity in platelets incubated with buffer (Plts) nLDL, and glycLDL. The mean ± SD are shown.

 


View larger version (15K):
[in this window]
[in a new window]
  		Figure 6. Ca2+-ATPase activity in platelets incubated with buffer (Plts), nLDL, and glycLDL. The mean ± SD are shown.

 


View larger version (14K):
[in this window]
[in a new window]
  		Figure 7. [Ca2+]i in platelets incubated with buffer (Plts), nLDL, and glycLDL. The mean ± SD are shown.

 
Discussion

Previous studies have shown that glucose autoxidizes in vitro, and nonenzymatic glycation can result in the generation of oxygen free radicals such as superoxide, which stimulate lipoprotein peroxidation (3, 7). In agreement with previous studies the present work demonstrated that LDL lipid peroxidation occurs during glycation treatment, as shown by the significant increase in TBARS in LDL incubated with glucose with respect to untreated lipoprotein.

The compositional changes in glycated LDL are accompanied by modifications of lipid order and polarity, as shown by the changes in the Gp value and in the position of maximum emission of Laurdan incorporated in glycLDL. The study of the correlation among the Gp value, the position of emission maximum, and TBARS values in LDL incubated in different experimental conditions suggests that the increase in polarity and the decrease in molecular order of LDL incubated with glucose are probably related to the lipid composition changes.

The physico-chemical properties of lipoproteins play a regulatory role in lipoprotein functions (regulation of lipoprotein metabolism and lipoprotein-lipoprotein and lipoprotein-cell interactions) (23); therefore, the modifications of molecular order and polarity in glycLDL could be of physiological and pathological relevance.

After incubation with glycLDL, platelets showed deep modifications in the activity of the plasma membrane transport enzymes (decreased Na+/K+-ATPase, increased Ca2+-ATPase activities), in the cytoplasmic Ca2+ concentrations, and in NO production. These biochemical changes were accompanied by a functional effect of glycLDL on platelet aggregation, which was significantly higher than in the presence of nLDL, confirming previous studies (24).

Not much is known about the biochemical modifications caused by the interaction between platelets and modified lipoproteins, except for recent data showing an inhibitory action of oxLDL on NOS and Ca2+-ATPase activities of platelet membranes (25, 26).

The changes observed in the present work in the activity of plasma membrane enzymes, such as Na+/K+-ATPase and Ca2+-ATPase, might be directly dependent on the interaction between glycLDL and the platelet cellular surface. In fact, it might be hypothesized that glycLDL that are deeply altered in their polarity and molecular order cause changes in the platelet plasma membranes, with altered arrangement of protein molecules within the membrane itself. This effect might also occur through equilibrium exchange processes, without the need of interaction with a specific membrane receptor (27).

With regard to [Ca2+]i, the increase in its concentration after incubation with glycLDL cannot be dependent on the inhibition of Ca2+-ATPase activity, as this enzyme was stimulated in the same conditions. As a consequence, this event can be caused by an increased influx of calcium across the plasma membrane or by a higher release from storage compartments. We might suggest a link with the reduced Na+/K+-ATPase activity, as an inhibition of the sodium pump might determine an increase in Na+/Ca2+ exchange and, therefore, in [Ca2+]i (28).

The mechanisms by which glycLDL modify platelet NO synthesis might involve the increased [Ca2+]i. In fact, the constitutive form of NOS present in normal human platelets is Ca2+-calmodulin dependent (29), and therefore increased cytosolic calcium concentrations are able to stimulate platelet NOS activity.

The increased [Ca2+]i observed after glycLDL incubation is consistent with the platelet activation demonstrated by the enhanced aggregation in response to ADP. In fact, it is well known that cytosolic concentrations of calcium play a major role in the regulation of platelet activation (30). On the contrary, the higher NO production might exert an antiaggregating effect (31), which is counteracted by the contemporaneous increase in platelet [Ca2+]i observed after glycLDL incubation. The stimulation of NO release in the presence of glycLDL might also damage platelet function, as it can produce increased amounts of the strong oxidant peroxynitrite under conditions of unbalance between NO and oxygen radicals (32).

The present data further indicate that the modifications observed in our previous work in platelets after incubation with LDL obtained from diabetic patients (33) cannot be simply obtained using glycLDL. There are some differences; Na+/K+-ATPase and Ca2+-ATPase activities as well as the maximal aggregation and [Ca2+]i are modified in the same way, whereas NO production follows an opposite trend. It must be underlined that the LDL from type 1 diabetic patients used in the previous work did not show increased concentrations of hydroperoxides, whereas glycLDL in the present work had high levels of TBARS. It is therefore difficult to evaluate whether the actions exerted by glycLDL on platelets are due to glycation or, most probably, by the combination of glycation and oxidation.

The data obtained in the present work with incubations of platelets with moxLDL suggest that the low levels of peroxidation products present in both glyc- and moxLDL are not able by themselves to cause modifications of platelet functions. The lack of effect of moxLDL on platelets found in the present investigation does not confirm a previous study reporting an activation of platelets by mildly oxidized LDL through a PLA2/cyclooxygenase-dependent pathway (8). However, it must be underlined that the LDL used for this previous work contained about 5-fold higher concentrations of TBARS, and the incubation was performed with 20-fold higher concentrations of moxLDL than in the present study.

In conclusion, the present work demonstrates that glycation induces compositional and structural changes in LDL, with modifications of molecular order and permeability and higher levels of lipid peroxidation products. Moreover, it suggests that an altered interaction between glycLDL and platelets might play a central role in the pathophysiology of the vascular complications of diabetes through modifications induced in cellular NO metabolism and ion transport.

Acknowledgments

Footnotes

Abbreviations: ATPase, Adenosine triphosphatase; [Ca2+]i, intracellular Ca2+ concentrations; glycLDL, glycated low density lipoproteins; Gp, generalized polarization; LDL, low density lipoproteins; moxLDL, minimally oxidized low density lipoproteins; nLDL, native low density lipoproteins; NO, nitric oxide; NOS, nitric oxide synthase; oxLDL, oxidized low density lipoproteins; Pi, inorganic phosphate; TBARS, thiobarbituric acid-reactive substances.

Received June 4, 2001.

Accepted January 28, 2002.

References

  1. Chung BH, Segrest JP, Ray MJ, Brunzell JD, Hokanson JE, Krauss RM, Beaudrie K, Cone JT 1986 Single verticle spin density gradient ultracentrifigation. Methods Enzymol 128:181–209[Medline]
  2. Fuhrman B, Judith O, Keidar S, Ben-Yaish L, Kaplan M, Aviram M 1997 Increased uptake of LDL by oxidized macrophages is the result of an initial enhanced LDL receptor activity and of a further progressive oxidation of LDL. Free Radical Biol Med 23: 34–46
  3. Kobayashi K, Watanabe J, Umeda F, Nawata H 1995 Glycation accelerates the oxidation of low density lipoprotein by copper ions. Endocr J 42:461–465[Medline]
  4. Makita T 1995 Glycation accelerates the oxidation of low-density lipoprotein by copper ions. Endocr J 42:461–465
  5. Millican SA, Schultz D, Bagga M, Coussons PJ, Muller K, Hunt JV 1998 Glucose-modified low density lipoprotein enhances human monocyte chemotaxis. Free Radical Res 28:533–542[Medline]
  6. Rabini RA, Ferretti G, Galassi R 1994 Modified fluidity and lipid composition in lipoproteins and platelet membranes from diabetic patients. Clin Biochem 27:381–385[CrossRef][Medline]
  7. Kawamura M, Heinecke JW, Chait A 1994 Pathophysiological concentrations of glucose promote oxidative modification of low density lipoprotein by a superoxide-dependent pathway. J Clin Invest 94:771–778
  8. Weidtmann A, Scheithe R, Hrboticky N, Pietsch A, Lorenz R, Siess W 1995 Mildly oxidized LDL induces platelet aggregation through activation of phospholipase A2. Arterioscler Thromb Vascular Biol 15:1131–1138[Abstract/Free Full Text]
  9. Yagi K 1987 Lipid peroxides and human diseases. Chem Phys Lipids 45:337–351[CrossRef][Medline]
  10. Lowry OH, Rosenbrough NJ, Farr AL, Randall RT 1951 Protein measurement with the Folin phenol reagent. J Biol Chem 192: 265–267
  11. Dousset N, Ferretti G, Taus M, Valdiguie P, Curatola G 1994 Fluorescence analysis of lipoprotein peroxidation. Methods Enzymol 233:459–469[CrossRef][Medline]
  12. Parasassi T, De Stasio G, D’Ubaldo A, Gratton E 1990 Phase fluctuation in phospholipid membranes revealed by Laurdan fluorescence. Biophys J 57:1179–1186[Medline]
  13. Rao GHR 1988 Measurement of ionized calcium in normal human blood platelets. Anal Biochem 169:400–404[CrossRef][Medline]
  14. Born GVB, Gross MJ 1972 The aggregation of blood platelets. J Physiol 168:178–181
  15. Weiss HJ, Rogers J 1972 Thrombocytopenia due to abnormalities in platelet release reaction. Blood 39:2–8
  16. Chakravarthy U, Hayes RG, Stitt AW, McAuley E, Archer DB 1998 Constitutive nitric oxide synthase expression in retinal vascular endothelial cells is suppressed by high glucose and advanced glycation and products. Diabetes 47:945–952[Abstract]
  17. Mazzanti L, Rabini RA, Faloia E, Fumelli P, Bertoli E, DePirro R 1990 Altered cellular calcium and sodium transport in diabetes mellitus. Diabetes 39:850–854[Abstract]
  18. Grynkiewicz G, Poenie M, Tsien RY 1985 A new generation of Ca2+ indicators with greatly improved fluorescence properties. J Biol Chem 6:3440–3450
  19. Enouf J, Bredoux R, Bourdeau N, Sarkadi B, Levy-Toledano S 1989 Further characterization of the plasma membranes, and intracellular membrane-associated platelet Ca2+-transport system. Biochem J 263:547–552[Medline]
  20. Fiske CH, Subbarow Y 1925 The colorimetric determination of phosphorus. J Biol Chem 66:375–400[Free Full Text]
  21. Kitao T, Hattori K 1983 Inhibition of erythrocyte ATPase activity by aclacinomycin and reverse effect of ascorbate on ATPase activity. Experientia 39:1362–1364[CrossRef][Medline]
  22. Davis FB, Davis PJ, Nat G, Blas SD, MacGillivray M, Gutman S, Feldman MJ 1985 The effect of in vivo glucose administration of human erythrocytes Ca2+-ATPase activity and on enzyme responsiveness in vitro to thyroid hormone and calmoduline. Diabetes 34:639–646[Abstract]
  23. Cerchi GM, Formato M, Demuro P, Masserini M, Varani I, De Luca G 1994 Modifications of low density lipoprotein induced by the interaction with human plasma glycosaminoglycan-protein complexes. Biochim Biophys Acta 1212:345–352[Medline]
  24. Watanabe J, Wohltmann HJ, Klein RL, Colwell JA, Lopes-Virella MF 1988 Enhancement of platelet aggregation by low density lipoproteins from IDDM patients. Diabetes 37:1652–1657[Abstract]
  25. Zhao B, Dierichs R, Miller FN, Dean WL 1991 Oxidized low density lipoproteins inhibits platelet plasma membrane Ca2+-ATPase. Cell Calcium 19:435–458
  26. Chen LY, Metha P, Metha JL 1996 Further evidence of the presence of constitutive and inducible nitric oxide synthase isoforms in human platelets. Cardiovasc Pharmacol 27:154–158[CrossRef][Medline]
  27. Owen JS, Gillet MP 1983 Plasma lipids, lipoproteins and cell membranes. Biochem Soc Trans 11:336–339[Medline]
  28. Rabini RA, Galassi R, Fumelli P, Dousset N, Solera ML, Valdiguie P, Curatola G, Ferretti G, Taus M, Mazzanti L 1994 Reduced Na+/K+-ATPase activity and plasma lysophosphatidylcholine concentration in diabetic patients. Diabetes 43:915–919[Abstract]
  29. McCabe TJ, Fulton D, Roman LJ, Sessa WC 2000 Enhanced electron flux and reduced calmodulin dissociation may explain "calcium-independent" eNOS activation by phosphorylation. J Biol Chem 275:6123–6128[Abstract/Free Full Text]
  30. Giovine M, Signorello MG, Pozzolini M, Leoncini G 1999 Regulation of L-arginine uptake by Ca(2+) in human platelets. FEBS Lett 461:43–46[CrossRef][Medline]
  31. Chiang TM, Cole F, Woo-Rasberry V, Kang ES 2001 Role of nitric oxide in collagen-platelet interaction: involvement of platelet nonintegrin collagen receptor nitrotyrosylation. Thromb Res 102:343–352[CrossRef][Medline]
  32. Brown AS, Moro MA, Masse JM, Cramer EM, Radomski M, Darley-Usmar V 1998 Nitric oxide-dependent and independent effects on human platelets treated with peroxinitrite. Cardiovasc Res 40:380–388[Abstract/Free Full Text]
  33. Rabini RA, Staffolani R, Martarelli D, Fumelli P, Ravaglia F, Dousset N, Curatola G, Mazzanti L 1998 Influence of low density lipoprotein from insulin-dependent diabetic patients on platelet functions. J Clin Endocrinol Metab 84:3770–3774[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 Arterioscler. Thromb. Vasc. Bio.Home page
C. P. Hodgkinson, R. C. Laxton, K. Patel, and S. Ye
Advanced Glycation End-Product of Low Density Lipoprotein Activates the Toll-Like 4 Receptor Pathway Implications for Diabetic Atherosclerosis
Arterioscler Thromb Vasc Biol, December 1, 2008; 28(12): 2275 - 2281.
[Abstract] [Full Text] [PDF]

Home page
 Am J EpidemiolHome page
A. Shankar, R. Klein, B. E. K. Klein, and S. E. Moss
Association between Glycosylated Hemoglobin Level and Cardiovascular and All-Cause Mortality in Type 1 Diabetes
Am. J. Epidemiol., August 15, 2007; 166(4): 393 - 402.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
C. Calzada, L. Coulon, D. Halimi, E. Le Coquil, V. Pruneta-Deloche, P. Moulin, G. Ponsin, E. Vericel, and M. Lagarde
In Vitro Glycoxidized Low-Density Lipoproteins and Low-Density Lipoproteins Isolated from Type 2 Diabetic Patients Activate Platelets via p38 Mitogen-Activated Protein Kinase
J. Clin. Endocrinol. Metab., May 1, 2007; 92(5): 1961 - 1964.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
A. Vignini, L. Nanetti, T. Bacchetti, G. Ferretti, G. Curatola, and L. Mazzanti
Modification Induced by Homocysteine and Low-Density Lipoprotein on Human Aortic Endothelial Cells: An In Vitro Study
J. Clin. Endocrinol. Metab., September 1, 2004; 89(9): 4558 - 4561.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ferretti, G.
Right arrow Articles by Mazzanti, L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ferretti, G.
Right arrow Articles by Mazzanti, L.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals