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The nature of the link (causal vs non-causal) between low 1,25-OH vitamin D and insulin resistance (IR) in patients with chronic kidney disease (CKD) remains elusive. We have now made a post hoc analysis of the effect of vitamin D receptor activation by paricalcitol on IR in the complete dataset of a double-blind, randomized, placebo controlled trial, the Paricalcitol and ENdothelial fuNction in chronic kidneY disease (PENNY).Eighty-eight patients with stage 3-4 CKD were randomized (1:1) to receive 2 μg/day paricalcitol or matching placebo for 12 weeks. IR was measured by five IR indices: the homeostasis model assessment of insulin resistance (HOMA-IR), the quantitative insulin sensitivity check index (QUICKI), the McAuley index, the HOMA corrected for adiponectin (HOMA-AD) and the Leptin-adiponectin ratio (LAR). As compared to placebo, paricalcitol produced the expected small rise in serum calcium (+0.07 mmol/L, P = 0.01) and phosphate (+0.08 mmol/L, P = 0.034) and the expected parathyroid hormone suppression (-96 pg/ml, P 0.001). However, the drug largely failed to affect the five indices of IR which remained unchanged both in the active and the placebo arm (paricalcitol vs placebo, P ranging from 0.25 to 0.62) and no effect modification of paricalcitol on IR by vitamin D or other parameters was registered.Paricalcitol treatment for 12 weeks does not improve IR in patients with stage 3-4 CKD. Low vitamin D receptor activation is not a causal factor for IR in the CKD population.

Vitamin D receptor activation (VDRA) ameliorates endothelial dysfunction in CKD patients but also increases phosphate and FGF-23, which may attenuate the beneficial effect of VDRA on endothelial function.This is a pre-specified secondary analysis of the PENNY trial (NCT01680198) testing the effect of phosphate and FGF-23 on the flow mediated vasodilatory (FMD) response to paricalcitol (PCT, 2 μg/day) and placebo over a 12-weeks treatment period. Eighty-eight stage G3-4 CKD patients were randomized to PCT (n = 44) and Placebo (n = 44). Endothelial function was assessed by measuring endothelium dependent forearm blood flow (FBF) response to ischemia. The FMD response was by the 61% higher in PCT treated patients than in those on placebo (P = 0.01). Phosphate (+11%, P = 0.039), calcium (+3%, P = 0.01) and, particularly so, FGF23 (+164%, P 0.001) increased in PCT treated patients. Changes in FMD by PCT associated inversely with phosphate (r = -0.37, P = 0.01) but were independent of FGF-23, calcium and PTH changes. The response to PCT was maximal in patients with no changes in phosphate (1st tertile), attenuated in those with mild-to-moderate rise in phosphate (2nd tertile) and abolished in those with the most pronounced phosphate increase (3rd tertile) (effect modification P = 0.009). No effect modification by FGF-23 and other variables was observed.The beneficial effect of PCT on endothelial function in CKD is maximal in patients with no or minimal changes in phosphate and it is abolished in patients with a pronounced phosphate rise. These findings generate the hypothesis that the endothelium protective effect by VDRA may be potentiated by phosphate lowering interventions.

Based on careful physical description, the effect of gate-length downscaling on the RF performance of double-gate fin field-effect transistors (finFETs) has been analyzed. Downscaling is beneficial to the device RF performance although the losses due to series parasitics increase. The source/drain series resistance in finFET largely limits the device RF performance, and the losses due to the gate resistance increase with reducing gate length. Double-gate finFETs have the potential to reach the RF International Technology Roadmap for Semiconductor targets in the few decananometer regime, but meeting the specification for gate length in the order of 10 nm may require further improvements.

Quantum interactions between the inversion channels of multigate devices and their resulting effects on charge distribution and carrier mobility are analyzed in this paper. Results of this analysis are then used to assess the role of volume inversion on the intrinsic RF performance of double-gate FinFETs. Thin-fin devices are beneficial to low-operating and high-performance powers, and wideband RF blocks, while they are detrimental to low-power cross coupled pair-based RF oscillators, and are more power hungry for high-performance oscillators. Also, we highlight that the intrinsic capacitance variation induced by the fin volume inversion dominates the power and wideband RF performance of FinFETs over the variation in carrier mobility. Accurate definition of fin below 8-10 nm will enable extreme RF performance devices

This paper investigates the extraction of channel length from split current-voltage (C-V) measurements of small gate length PMOS transistors. Using device simulations, including quantum-mechanical effects, scanning spreading resistance measurements, and process simulations, the authors correlate the variation of the overlap capacitance with the gate voltage, and the length of the lateral junction doping profile. It is suggested that an accurate extraction of the metallurgical and effective gate length can be obtained from C-V measurements subtracting the overlap capacitance at V/sub G/=V/sub FB/ and V/sub G/=V/sub FB/+0.8V.

Three gate stacks for the 45-nm node are analyzed from an RF perspective. The authors present an expression of the gate resistance valid for all three stacks, quantify the differences each stack has on several small-signal RF figures-of-merit and on the RF noise parameters, and demonstrate that devices with fully silicided gates will enable ultralow-power/low-noise RF applications, while the performance of transistors using multilayer gate stacks are limited by large contact resistance. Although offering better bandwidth and noise characteristics than the poly/silicide stack, the deposited metal stack will lose its advantage in devices requiring higher gate work functions than in planar bulk CMOS transistors.

We analyze in detail the requirements for the detailed physical modeling of nanoscale MOSFETs and show that Schro/spl uml/dinger drift-diffusion per subband simulations are adequate for the inverse modeling of bulk-Si MOSFETs with gate length down to 40 nm (channel length down to 26 nm) from their dc electrical characterization. We show that a proper treatment of quantum effects both in the channel and in the polysilicon gate through the direct solution of Schro/spl uml/dinger equation, and a transport model based on two-dimensional subbands are required for accurate and-after calibration-predictive modeling. The model is included in the NANOTCAD2D code (Curatola and Iannaccone, 2003). We also evaluate the performance gap to ballistic transport, by comparing the experiments with simulations based on a fully ballistic transport model on the devices structures extracted with the inverse modeling procedure.

This paper presents detailed DC and AC numerical simulations of thermal effects in nanoscale FinFET devices. Three–dimensional electro–thermal numerical simulations, including a realistic description of the source, drain and gate interconnections, are validated by comparison with DC I–V and AC small–signal parameters. The importance of a realistic description of the interconnects for the AC simulation of FinFETs is discussed.

We have simulated the electronic properties of silicon-germanium electron waveguides defined by selective etching on a SiGe heterostructure. In particular, we have investigated the dependence of quantum confinement and of one-dimensional subband separation on the waveguide width. Indeed, a larger subband separation means a larger dephasing length and larger electron mobility in the waveguide, and therefore increased possibilities of detecting mesoscopic transport effects. Accurate modelling of SiGe electron waveguides requires us to take into account the effect of strain in the SiGe heterostructure and of the interface states at the exposed SiGe surface, and to solve the Poisson-Schrodinger equation in two dimensions. Results are also shown for a structure in which a gate electrode is evaporated onto the SiGe waveguide, realizing a three-terminal device in which the gate voltage is used to control the number of propagating modes, and therefore the conductance of the channel.

This paper discusses self-heating effects in different silicon-on-insulator architectures by 3D electro-thermal simulations. First of all, we compare different device architectures such as planar single- and double-gate transistors, as well as FinFETs. In the second part of the article, we focus on nanoscale FinFET devices and we study the dependence of self-heating on device-structure parameters such as buried oxide thickness, source/drain extension length, fin pitch and fin height. The electron transport model has been calibrated against Monte Carlo simulations at various temperatures. The results show that under stationary conditions the rise of temperature is not negligible, and self-heating severely impacts the device performance; however, its dependence on the geometrical parameters is weak.

This paper presents a detailed thermal analysis of nanoscale FinFET devices. A three-dimensional electro-thermal device simulator, calibrated against Monte Carlo simulations at various temperatures, is adopted in order to study self-heating effects in Fin-FETs, and their dependence on geometrical parameters such as buried oxide thickness, source/drain extension length, fin-pitch and fin height.

The interaction between lipoproteins and the platelet membrane has been proved to cause a modification in cellular functions. We studied 12 men with insulin-dependent diabetes mellitus (IDDM), 14 men with noninsulin-dependent diabetes mellitus (NIDDM), and 26 age-matched healthy men on the same diet. We determined fluidity by measuring the fluorescence polarization (P) of the probe 1,6-diphenyl-1,3,5-hexatriene (DPH) both in platelet membranes and in lipoproteins isolated by ultracentrifugation in NaBr density gradient. The lipid composition of lipoproteins and of platelet membranes was determined by enzymatic methods. The fluidity of platelet membranes was significantly increased both in patients affected by NIDDM and in subjects with IDDM compared with normal subjects. Low-density lipoproteins (LDL) showed an increased fluidity only in NIDDM patients. A percent increase in the triglyceride content was observed in all lipoprotein fractions in diabetic subjects. Increased phospholipid content was found in the platelet membranes from IDDM and NIDDM patients. The change in LDL fluidity observed in NIDDM patients might determine altered interactions between the lipoprotein and cellular receptors. The role of lipoproteins in the modulation of the platelet membrane properties in diabetes mellitus deserves further studies.

Many drugs and chemicals have been shown to induce modifications of the physicochemical properties of cellular membranes. In this study we investigated the changes in fluidity of erythrocyte membrane from epileptic patients under different pharmacological treatments, with respect to healthy controls, by using trimethylammonium-1,6-diphenyl-1,3,5-hexatriene (TMA-DPH) fluorescence polarization. The increase in TMA-DPH fluorescence polarization values observed in epileptic patients indicated a decrease in membrane fluidity. Since the analysis of erythrocyte membrane composition did not reveal significant differences between the two groups studied, a correlation with membrane lipoperoxide content was tried, as different drugs and chemicals elicit in vivo alterations resulting in peroxidation of membrane lipids. Therefore the presence of peroxidation products in the blood and the possible correlation with membrane lipoperoxide were studied. Although a direct causal linkage cannot be proved we can hypothesize that exogenous compounds such as antiepileptic drugs could modify membrane fluidity by increasing membrane lipid peroxidation. Moreover the increase of peroxidative products in the blood could indicate that the peroxidative damage might propagate through the formation of new free radical species. The possibility of using erythrocyte membrane as a model system to analyze antiepileptic drug side effects is advanced.

Vt-mismatch, and thus SRAM scalability, is greatly improved in narrow SOI FinFETs, with respect to planar bulk, because of their undoped channel and near-ideal gate control. We show by simulations and by measurements that in FinFETs, unlike planar bulk, beta-mismatch becomes dominant, leading to radically different SRAM characteristics. By careful process tuning, we demonstrate a substantial reduction in beta-mismatch. We show the impact of this novel mismatch behavior on SRAM performance and yield under various optimization strategies and thereby provide guidelines for SRAM design in a FinFET technology.

This paper presents a detailed thermal analysis of nanoscale FinFET devices. A three-dimensional electro-thermal device simulator, calibrated against Monte Carlo simulations at various temperatures, is adopted in order to study self-heating effects in Fin-FETs, and their dependence on geometrical parameters such as buried oxide thickness, source/drain extension length, fin-pitch and fin height.

Excellent performance (995 muA/mum at Ioff=94 n A/mum and Vdd=lV) and short channel effect control are achieved for tall, narrow FinFETs without mobility enhancement. Near-ideal fin/gate profiles are achieved with standard 193 nm immersion lithography and dry etch. PVD TiN electrodes on Hf SiO dielectrics are shown to give improved NMOS performance over PEALD TiN whilst poorer conformality, for both dielectric and gate electrode, does not appear to impact scalability or performance. Excellent PMOS performance is achieved for both PEALD and PVD TiN. A new model for threshold voltage VT variability is shown to explain this dependence upon fin width and gate length.

We propose an efficient and fast algorithm to solve the coupled Poisson-Schrodinger and Boltzmann transport equations (BTE) in two dimensions. The BTE is solved in the relaxation time approximation within each subband obtained from the direct solution of the Schrodinger equation. The proposed approach, considering a subband-based transport formalism, allows to fully explore the entire range from drift-diffusion to ballistic regime in nanoscale field-effect transistors. Quantum effects are also fully taken into account by the direct solution of the Schrodinger equation. The model is implemented in the NanoTCAD2D device simulator and used to study the device performance of a 25-nm channel-length MOSFET. The influence of scattering on the electron distribution function and on device characteristics is analyzed in detail.

This is a clinical case of a patient suspected to have a lymphoma. Later on, other diagnostic procedures and particularly a neck ultrasound, revealed an idiopathic hyperparathyroidism.

With few exceptions renal volume is markedly reduced in patients with end-stage renal disease, a phenomenon which is almost always accompanied by a progressive loss of renal compliance secondary to renal structure fibrosis. We have observed a remarkable renal compliance during an episode of acute pyelonephritis in a patient on long-term dialysis.

A forty-nine year old man was admitted to the Renal Unit of our Hospital because of renal failure, loin pain, low grade fever and loss of weight. It was done a complete work-up. The ultrasound and the computed tomography of the abdomen were very helpful to get the right diagnosis.

We investigate the performance of bulk silicon and strained-silicon nanoscale MOSFETs in the ballistic regime, with the purpose of identifying possible advantages of silicon-germanium technology in devices approaching the ballistic regime. Investigation is performed with a 2D program that solves in a self-consistent way the Poisson equation, the Schrodinger equation with density functional theory, and the continuity equation for ballistic electrons. In the ballistic regime, when mobility has no physical meaning, strained-silicon FETs seem only to provide smaller short channel effects, but no improvement as far as transconductance and drive current are concerned.

Liver disease is accompanied by major quantitative and qualitative modifications in plasma lipoprotein metabolism. Alterations in plasma lipoprotein composition and a lower susceptibility to in vitro peroxidation of low density lipoprotein (LDL) and erythrocyte membranes have been observed in liver cirrhosis. The main objective of the present work was to investigate LDL chemical composition and fluidity in liver cirrhosis using the fluorescence polarization (Pf) of the 1,6-diphenyl-1,3,5-hexatriene (DPH) probe.The chemical composition of LDL was studied in 12 cirrhotic patients and 22 controls by conventional methods and its fatty acid composition by gas chromatography. LDL fluidity was determined by measuring the DPH Pf values. A decrease in molecular order was demonstrated by the significant (p0.05) decrease in Pf values in the cirrhotics. Modifications in LDL fluidity are correlated with its composition. A significant increase in triglyceride content (p0.05), and significant increases in triglyceride/protein and triglyceride/phospholipid ratios were observed in the cirrhotics.Our results demonstrate that the higher LDL fluidity of cirrhotic patients may be due to an increased triglyceride content.

The aim of this study was to evaluate changes in the concentration of certain components of human unstimulated whole saliva during aging, in order to better understand the role played by aging in oral health. In particular, we studied total protein concentration, alpha-amylase activity, sialic acid content and calcium and phosphorus concentrations in 100 healthy subjects of both genders, aged between 10 and 80 years, who were subdivided into four groups according to their age: 10-25 years, 26-40 years, 41-65 years, and 66-80 years. Other than sialic acid, the concentrations of the components studied were not affected by age. There was a significant negative correlation between sialic acid content and age. Our data indicate the presence of a decreased submandibular/sublingual function with aging, thus suggesting the possibility of a concomitant reduction in the modulating action of unstimulated whole saliva on the oral flora.

Na+,K(+)-ATPase activity was evaluated in relation to membrane composition and molecular organization in erythrocyte membranes from obese patients by the amphyphylic molecule 6-dodecanoyl-2-dimethylamino-naphthalene (Laurdan). Its possible relationship with fat distribution and hyperinsulinaemia was also investigated.Subjects were 10 obese men (OM), 12 women with subcutaneous obesity (FSO), 10 women with abdominal obesity (FAO) and 41 healthy lean subjects, 26 women (FC) and 15 men (MC). An oral glucose tolerance test was administered to all subjects to evaluate insulin secretion and glucose tolerance.Na+,K(+)-ATPase activity was increased in all obese patients. Values were higher in FSO and FAO than in FC (with FAO greater than FSO) and in OM than in MC. The erythrocyte membrane cholesterol-to-phospholipid ratio was increased in obese patients and was significantly different in FSO patients compared with FC. The erythrocyte membrane protein-to-phospholipid ratio was also increased in all obese subjects, reaching statistical significance only in FSO vs. FC. The liquid crystalline phase, as tested by Laurdan generalized polarization (GP), was decreased in obese patients, indicating the presence of greater molecular environmental order; all patients groups showed lower GP values than control subjects, but only FAO reached statistical significance compared with FC. There was no evident correlation between membrane Na+,K(+)-ATPase activity and insulin levels, nor did membrane composition and properties show any evident relationship with insulin levels.Both increased Na+,K(+)-ATPase activity and altered fluidity and lipid composition were observed in the erythrocyte membrane of all obese patients. These findings are in line with previous observations by our group and indicate that the changes in Na+,K(+)-ATPase activity observed in obese patients could be related to changes in plasma membrane organization and composition.

The aim of our study was to investigate the effect of Cu2+ catalyzed oxidation on VLDL physico-chemical properties and secondary structure of apo B-100. Incubation of very low density lipoproteins with copper ions resulted in a decrease in tryptophan and lysine residues parallel to lipid peroxidation products, conjugated dienes and TBARS. Fluorescence polarization showed an increase in the molecular order at the lipoprotein surface of VLDL, as demonstrated by the increase in Pf values of DPH. The secondary structure of apo B-100 was investigated by infrared spectroscopy. Increased order and structural changes, as observed after oxidative stress on VLDL, could be of relevance in the abnormal interactions between lipoproteins and cell membranes.

Nitric oxide (NO) produced by platelet nitric oxide synthase (NOS) inhibits platelet activation by increased cytoplasmic cGMP levels. The aim of this study was to investigate platelet NOS activity in insulin-dependent (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM), which are characterized by enhanced platelet activation. HbA1 c levels, platelet NOS and platelet membrane Na+/K+ ATPase activity were determined in 19 IDDM patients, 21 NIDDM patients and 31 healthy control subjects. NOS activity was measured by a spectrophotometric method based on NO-dependent oxidation of oxyhaemoglobin to met-haemoglobin. Na+/K+ ATPase activity was measured by the method of Kitao and Hattori. Both NOS and Na+/K+ ATPase activity were significantly reduced in diabetic subjects compared with control subjects. NOS showed a significant negative relation with HbA1 c levels and a positive relation with Na+/K+ ATPase activity in diabetic patients. It is hypothesized that the decreased NOS activity might play a role in the pathogenesis of diabetic vascular complications. [Diabetologia (1998) 41: 101–104]

Phase-modulation fluorescence lifetime measurements were used to study the single Trp residue of the Ca(2+)-binding protein S-100a both in the absence and in the presence of Ca2+ and/or Mg2+. Trp fluorescence decay for the protein was satisfactorily described by Lorentzian lifetime distributions centered around two components (approximately 4 ns and 0.5 ns). Lifetime values were unchanged by 2 mM Ca2+, but the fractional intensity associated with longer lifetime increased up to 75%. In the presence of Mg2+, the Ca2+ induced increase of the fractional intensity associated with longer lifetime was only 57%. For the protein in buffer, about the 85% of the recovered anisotropy was associated to a rotational correlation time of 6.7 ns. After the addition of Ca2+, this value was increased to 16.08 ns. In the presence of Mg2+, Ca+2 increased the rotational correlation time to 33.75 ns. Similar studies were performed with S-100a interacting with egg phosphatidylcholine vesicles (SUV). Our data suggest that the conformation of the protein may be influenced by structural features of the lipidic membrane. Moreover, data obtained in the presence of Mg2+ indicate some interaction between lipids and S-100, likely mediated by this ion.

Using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its derivative trimethylammonium -1,6-diphenyl-1,3,5-hexatriene (TMA-DPH), we have investigated the fluidity in erythrocyte membranes isolated from intraoperatively and postoperatively recovered erythrocytes, compared to membranes isolated from untreated erythrocytes or stored red blood cells (RBCs). Fluorescence polarization (Pf) of DPH and TMA-DPH was not significantly modified in membranes isolated from intraoperatively and postoperatively recovered RBCs compared to membranes isolated from untreated fresh RBCs or stored RBCs. However, using 2-dimethyl-amino-6-lauroyl-naphtalene (Laurdan), a very sensitive molecule, a significant increase in polarity in membranes from stored RBCs compared to untreated, intraoperatively and postoperatively recovered RBCs was observed. Moreover, there was significantly higher susceptibility to oxidative stress in membranes isolated from stored RBCs, compared to untreated and intraoperatively or postoperatively recovered RBC membranes, both at baseline and after oxidative stress. Our results suggest that intraoperative and postoperative recovered RBCs are less damaged than stored RBCs.

We have studied the lipoprotein chemical composition and fluidity, using the fluorescence polarization of the probe 1,6-diphenyl-1,3,5-hexatriene (DPH) in two age- and sex-matched groups of subjects (14 healthy normolipidemic children and 15 psoriatic children). The compositional study has shown a significant increase of the percentage content in triacylglycerol and a significant decrease of the apo-protein content in all lipoprotein fractions of psoriatic children compared to the controls. A significant increase of the percentage content in total cholesterol and of the cholesterol/protein ratio has also been observed in low-density lipoproteins (LDL) and in high-density lipoproteins (HDL) of psoriatic children. The compositional changes were associated with alterations of fluidity in LDL and HDL of psoriatic patients. The modifications of lipoprotein composition and fluidity observed in psoriatic patients could be of physiopathological and clinical relevance in relation to the pathogenesis of the disease.

Aim of our study was to investigate the effect of the desialylation induced by neuraminidase treatment on low density lipoprotein susceptibility to peroxidative stress induced by incubation with copper ions. Our results show that peroxidative stress induces the formation of aggregates that was not observed in desialylated low density lipoproteins. An increase in thiobarbituric reactive substances and a decrease in polyunsaturated fatty acids content have been shown in oxidized LDL. These modifications were less pronounced in oxidized low density lipoproteins previously treated by neuraminidase. The present data suggest a lower susceptibility to peroxidative stress in previously desialylated low density lipoproteins.

Psoriasis, a chronic inflammatory skin disease characterized by an aberration of lipid metabolism, has been associated with an increased risk for atherosclerosis. Since oxidatively modified lipoproteins are involved in the pathogenesis of atherosclerosis, we investigated the lipid composition and in vitro induced peroxidation of very low density lipoproteins (VLDL) and low density lipoproteins (LDL) from psoriatic patients. 11 male adult psoriatics and 16 male age-matched healthy subjects were studied. Lipid peroxidation of VLDL and LDL was performed by incubation with CuSO4 for 24 h at 37 degrees C. The compositional analysis showed a significant increase in triglycerides and phospholipids, both in VLDL (p0.05) and in LDL (p0.001) from psoriatic patients, compared with controls. Moreover a significant increase in total cholesterol (TC) (p0.01) and apoprotein (P) (p0.05) was found in LDL from psoriatics. The levels of thiobarbituric acid reactive substances (TBARS), as a measurement of lipid peroxidation, were significantly higher in Ox-VLDL and in Ox-LDL from psoriatics (p0.01) than the corresponding values in controls. Moreover, basal values of TBARS were significantly higher in VLDL and LDL from psoriatic patients than those from controls. In conclusion, the lipoprotein compositional changes associated with the modifications of TBARS before and after Cu2+ treatment of lipoproteins may suggest an increased risk for atherosclerosis in adult psoriatic patients.

The fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) and DPH derivatives have been used to characterize structural and physicochemical properties of specific membrane domains. Steady-state and fluorescence decay measurements of three probes, DPH (1,6-diphenyl-1,3,5-hexatriene), TMA-DPH [1-(4-trimethyl-ammonium-phenyl)-6-phenyl-1,3,5-hexatriene], and a phosphatidylcholine derivative of DPH, DPH-pPC [2-(3-(diphenylhexatriene)propanoyl)-3-pamitoyl-L-α-phosphatidyl choline], have been performed in erythrocyte membranes and in lymphocyte plasma membranes. The steady-state fluorescence polarization of the three probes showed a similar trend in both membranes. In fact either in erythrocyte or in lymphocyte plasma membranes the fluorescence polarization values of DPH-pPC and TMA-DPH were similar, but significantly higher with respect to DPH. A better characterization of erythrocyte and lymphocyte plasma membranes was possible by using fluorescence decay measurements. The data suggest the possible use of different DPH derivatives to characterize specific domains in biological membranes.

The modifications of the physico-chemical properties of the high density lipoprotein (HDL) before and after in vitro induced oxidation by copper ions have been studied using the fluorescence polarization (Pf) of the phosphatidylcholine derivative of 1,6-diphenyl-1,3,5-hexatriene (DPH-PC) and of the cationic derivative (TMA-DPH). We have observed that HDL oxidation is associated with a decrease of the molecular order at the lipoprotein surface as demonstrated by the increase in Pf with respect to untreated HDL. Moreover in oxidized HDL the polarity-sensitive probe laurdan has shown a decrease of the polarity in its microenvironment. It has been suggested that a decrease in HDL fluidity would inhibit cholesterol reverse transport from peripheral tissues in form of HDL core cholesteryl esters. Peroxidation of HDL, if occurring in vivo, could contribute to the progress of atherogenesis by decreasing cholesterol efflux from peripheral tissues.

Using static and dynamic fluorescence we studied the fluorescence properties of a phosphatidylcholine analog of 1,6-diphenyl-1,3,5-hexatriene (DPH-PC) incorporated in lymphocyte plasma membranes with respect to DPH and its cationic derivative 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH), in order to study if phospholipid derivatives of DPH may be used to investigate structural and physicochemical properties of specific membrane lipid domains. DPH-PC and TMA-DPH showed similar fluorescence polarization values that were significantly higher with respect to DPH, suggesting a localization of the fluorescent portion of DPH-PC in a more ordered region of the membrane which was probably due to the elecrostatic interactions between phospholipid head-groups. The localization of the fluorescent moiety of DPH-PC near the membrane surface was also supported by the study of the fluorescence decay of the three probes using frequency-domain fluorometry. The main lifetime component of DPH-PC was rather similar to that of TMA-DPH (6.74 versus 6.24, ns) but considerably lower with respect to DPH (10.52 ns), in agreement with data obtained from exponential analysis. In lymphocyte membranes obtained from concanavalin A treated cells, a significant decrease of fluorescence polarization has been shown with DPH and its phosphatidylcholine derivative, but not with TMA-DPH. In liposomes obtained from total lipids extracted from lymphocyte membranes, a decrease of fluorescence polarization has been observed only with DPH. Our results suggest that DPH-PC localizes the fluorescent portion of its molecule in membrane microenvironments of different properties with respect to those probed by DPH and TMA-DPH. The use of DPH-phospholipid derivatives and other DPH-probes may represent an useful tool to study plasma membrane heterogeneity in biological membranes.

The susceptibility to peroxidative stress of low density lipoprotein (LDL), induced by incubation with CuSO4, has been studied in eleven diabetic patients and eleven control subjects. Our results suggest that oxidized LDL (OX-LDL) of diabetic patients have a significant higher reactivity to 2,4,6-trinitrobenzene sulfonic acid (TNBS) than controls, that indicates a lower susceptibility of LDL to oxidative stress. Furthermore using the fluorescence polarization (Pf) of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its phosphatidylcholine derivative (DPH-PC) we have shown that peroxidation induces a decrease of fluidity in OX-LDL of controls and diabetic patients, both at the lipoprotein surface, where is localized DPH-PC and at the interface between lipoprotein surface and core which is probed by DPH.

In this study we have demonstrated a transfer of a phosphatidylcholine derivative of 1,6-diphenyl-1,3,5-hexatriene (DPH-PC) from self-quenched lipid vesicles to intact lymphocytes. Membrane labeling was followed measuring the time dependent reexpression of fluorescence. The results of fluorescence quenching by 2,4,6-trinitrobenzene sulfonate and the decrease of fluorescence polarization values during incubation at 37 degrees C, suggest that the probe could remain localized at level of the plasma membrane until 20-30 minutes. DPH-PC is identical to the natural phospholipid with respect to head group structure and polarity therefore we suggest that under appropriate experimental conditions, it could represent an useful tool to study the physico-chemical properties of specific phospholipid domains in the plasma membrane of intact cells.

The effect of platelet activating factor, PAF, on the erythrocyte membrane heterogeneity was investigated by measuring the steady-state fluorescence anisotropy and fluorescence decay of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated in hemoglobin-free erythrocyte membranes. PAF induced a significant increase of the lipid order in the exterior part of the membrane and a decrease in membrane heterogeneity. These results indicate that PAF may cause changes in the physico-chemical structure of the erythrocyte membrane.

We have studied the metabolic response to changes in calcium in 15 hypercalciuric essential hypertensives, in 8 normotensive hypercalciuric stone formers and in 11 normotensive healthy subjects matched for age and sex. At variance with hypercalciuric stone formers, at low calcium intake hypercalciuric hypertensives did not appropriately reduce urinary calcium excretion and developed mild hypocalcemia. Furthermore, the PTH response to calcium deprivation was not appropriately enhanced in these patients. The data indicate that different mechanisms prevail in these two forms of hypercalciuria: the renal in essential hypertension and the intestinal in urolithiasis.

Human erythrocytes were separated using Percoll/Albumin density gradient centrifugation into 5 subpopulations which represent cell subpopulations of different ages. The physico-chemical properties of the membranes and their lipid extracts, prepared from the 5 subpopulations, were studied by 1,6-diphenyl-1,3,5-hexatriene fluorescence polarization and by Fourier Transform Infrared Spectroscopy respectively. The fluorescence polarization data show a decrease of membrane fluidity in the youngest erythrocyte fraction and the infrared spectroscopy reveals a lower degree of unsaturation of the lipids from this fraction. Changes of membrane fluidity among the 5 erythrocyte subpopulations is assigned to the variations of the degree of unsaturations of lipids rather than to variations of cholesterol content.

Membrane fluidity of erythrocytes obtained from 15 children with trisomy 21 and 20 healthy controls were studied by measuring steady-state fluorescence anisotropy and fluorescence lifetime of 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated in hemoglobin-free erythrocyte membranes. Our results demonstrate a significant decrease in DPH fluorescence anisotropy and a significant increase in TMA-DPH fluorescence anistropy in erythrocytes from subjects with trisomy 21. No significant differences between the two groups were observed in the fluorescence lifetime of DPH and TMA-DPH. These data suggest an increase in membrane fluidity in the interior part of the membrane and a decrease in fluidity at the lipid-water interface region. This could be in part attributed to an increased oxidative damage in trisomy 21.

The lipid composition and microviscosity of erythrocyte membranes have been studied in chronic alcoholics with macrocytosis and minimal liver dysfunction. The findings have been compared with those obtained in subjects with macrocytosis not related to ethanol abuse. In all instances, macrocytosis was accompanied by an increased microviscosity of erythrocyte membranes, together with an increase of the cholesterol/phospholipid and of saturated/unsaturated fatty acids ratio. Both microviscosity and saturated/unsaturated ratio were significantly higher in alcoholics compared to subjects with macrocytosis not related to ethanol abuse. These findings confirm that altered lipid composition and fluidity of erythrocyte membrane may be observed in chronic alcoholics with minimal liver dysfunction, possibly due to the "stabilising" properties of ethanol - among a number of drugs- on biological membranes.

Fluorescence polarisation of 1,6-diphenyl-1,3,5-hexatriene was used to study the lymphocyte membrane in rheumatoid arthritis. The increase of polarisation value in the patients (n = 27) compared with healthy controls (n = 32) suggests a decrease of membrane fluidity. Moreover, erythrocyte sedimentation rate (ESR) and plasma fibrinogen concentrations were positively correlated with lymphocyte fluorescence polarisation values (r = 0.66 and r = 0.76 respectively). The results suggest that the changes in lymphocyte membrane fluidity could be involved in the pathogenetic mechanism of rheumatoid arthritis.