Evaluating the effect of the protector cap for castable implant abutments on reverse tightening values.

STATEMENT OF PROBLEM: Screw loosening is the most common mechanical complication with implant prostheses. How the alteration of implant-to-abutment connection surfaces that occurs during laboratory procedures affects screw loosening is unclear. PURPOSE: The purpose of this in vitro study was to compare the reverse tightening value (RTV) differences between custom castable abutments before casting, after casting in a conventional manner, and after casting with custom protector caps and pegs. MATERIAL AND METHODS: Thirty implants with a standard-diameter conical connection (NobelReplace Conical Connection 4.3×13 mm; Nobel Biocare AG) and 30 premachined 4.3-mm GoldAdapt abutments (GoldAdapt; Nobel Biocare AG) were selected for this study. Specimens were divided into 3 groups (n=10): the uncast custom castable abutment group (UCCA) in which abutments were new and not cast; the unprotected custom castable abutment group (UPCCA) in which abutments were cast and devested with airborne-particle abrasion; and the protected custom castable abutment group (PCCA) in which abutments were cast by using protector caps and pegs made by milling zirconia and then devested with airborne-particle abrasion. All abutments in each group were tightened to 35 Ncm with a calibrated digital tightening device. After 10 minutes, all screws were retightened to 35 Ncm. At 3 hours, each screw was loosened, and the value at which the initial loosening occurred was documented as the RTV. The results were statistically analyzed with 1-way ANOVA to explore differences, and post hoc tests with Tukey adjustment were used for multiple comparisons. RESULTS: Among the tested groups, the mean RTV ranged from 19.89 Ncm to 27.19 Ncm: UCCA 27.19 Ncm, UPCCA 19.89 Ncm, and PCCA 24.24 Ncm. A significant difference was found among the tested groups (P<.05). CONCLUSIONS: Casting procedures, especially devestment with airborne-particle abrasion, affected implant-abutment connections and the seat site of the screw. Protecting the implant connection site and the seat site of the abutment screw with protector caps and pegs prevented a significant loss of the RTV.

Asymmetric dimethylarginine and symmetric dimethylarginine prospectively relates to carotid wall thickening in black men: the SABPA study.

The relationship of both asymmetric (ADMA) and symmetric (SDMA) dimethylarginine with carotid wall thickness is inconclusive especially among black populations. We aimed to compare carotid intima media thickness (cIMT) and dimethylarginine levels in 75 black and 91 white men at baseline and after a 3-year follow-up, and to investigate associations of percentage change in cIMT with percentage change in dimethylarginine levels (ADMA and SDMA). Plasma levels of ADMA and SDMA were determined with a liquid chromatography mass spectrometry method and B-mode ultrasonography was used to determine the cIMT at baseline and follow-up. In black men, mean cIMT (p = 0.79) and ADMA levels (p = 0.67) remained the same, but SDMA levels were lower (p < 0.001) when comparing baseline and follow-up. In white men, cIMT increased (p < 0.001), but both mean ADMA and SDMA levels decreased (p < 0.001) over time. In black men, percentage change in cIMT was positively associated with percentage change in ADMA (R 2 = 0.49; ß = 0.46; p < 0.001) and percentage change in SDMA (R 2 = 0.46; ß = 0.41; p < 0.001). These associations were absent in the white men. Despite lower mean SDMA and similar ADMA and cIMT in black men, percentage change in cIMT was independently associated with percentage change in ADMA and percentage change in SDMA. These results suggest an important role for ADMA and SDMA lowering strategies to delay carotid wall thickening, especially in black populations prone to the development of cardiovascular disease.

Clinical efficacy of polyvinyl siloxane impression materials using the one-step two-viscosity impression technique.

STATEMENT OF PROBLEM: Impression making is a challenging clinical procedure for both patients and dentists. PURPOSE: The purpose of this clinical study was to compare a recently introduced fast-setting polyvinyl siloxane (PVS) impression material with heavy body/light body (HB/LB) combination (Imprint 4; 3M ESPE) (experimental group) with a conventional PVS impression material with HB/LB combination (Imprint 3; 3M ESPE) (control group), using the 1-step 2-viscosity impression technique. MATERIAL AND METHODS: Two definitive impressions (1 of each material combination) were made of 20 crown preparations from 20 participants. The quality of impressions was rated by 3 evaluators (clinical evaluator, clinical operator, and dental technician) and by the patients for the level of comfort and taste of the impression materials. The order in which the 2 impressions were made with each material combination was randomized for each crown preparation. A paired t test for paired means and McNemar test for paired proportions were used for statistical comparisons (α=.05). RESULTS: Participants rated the comfort of the impression making with the experimental group significantly higher than that with the control group (P=.001). No significant differences were found in participants' rating for the taste of the impression materials (P=.46). The viscosity for tray material was rated as significantly better for the control group by the clinical operator (P=.004). The readability of the impression and visibility around the finish line were rated as significantly better for the experimental group than for the control group (P<.001). Except for the ease of removal of the stone (RS), the ratings for the 2 groups by the dental technician were similar. The ease of RS was rated as significantly better for the experimental group (P<.001). Eleven dies from the control and 9 from the experimental group were selected for fabrication of the definitive crowns (P=.65). CONCLUSION: Within the limitations of this clinical study, no significant differences were found in the overall clinical performance of the experimental and the control groups. Impressions made with both materials were clinically acceptable. Participants rated the comfort provided by the experimental group significantly better than that of the control group.

A simplified technique for recording an implant-supported ovate pontic site in the esthetic zone.

Implant-supported fixed dental prostheses present an esthetic challenge, especially when an ovate pontic site has been progressively developed during the guided soft-tissue healing process with an interim restoration. This article describes a technique for an accurate capturing of the molded ovate pontic site of an implant-supported fixed dental prostheses and for transferring it to the definitive cast, which facilitates the dental ceramist's ability to design and fabricate an ovate pontic with adequate intaglio contours.

The role of cements in dental lant success, Part I.

Peri-implant disease can be the result of residual excess cement. While there is no ideal implant restorative cement, the clinician must be aware that the material selection for implant restorations should not be based on properties which are more suited to restoration of the natural dentition. More appropriate criteria would be those unique to implants and the specific challenges these medical devices bring to the restorative dentist.

A comparison of the association between glomerular filtration and L-arginine status in HIV-infected and uninfected African men: the SAfrEIC study.

Hypertension, a major risk factor for cardiovascular disease worldwide, is increasing significantly in urbanised South Africans. Impaired glomerular filtration is a potential contributor to hypertension. Although HIV infection is widespread, little is known regarding its contribution to diminished estimated glomerular filtration rate (eGFR) and, in turn, hypertension in Africans. We compared eGFRs and cardiovascular profiles of newly identified HIV infected African men (N=53) not yet undergoing anti-retroviral therapy, and uninfected African men of similar age and anthropometry. The aim of the study was to determine whether eGFR is diminished in treatment naive HIV infected individuals and whether eGFR is associated with a potential modulator of hypertension, namely serum L-arginine. Cardiovascular risk factor profiles of HIV infected and uninfected men were similar. In men with healthy eGFRs >90 ml min(-1) per 1.73 m(2), eGFR was significantly lower with HIV infection (114 (90; 147)) compared with that in uninfected men: (120 (91; 168)), P=0.043. Despite the absence of clinically-diagnosed renal dysfunction, eGFR associated significantly with serum L-arginine only in HIV infected men (R(2)=0.277, ß=-0.299, P=0.034), whereas L-arginine did not stay in the model for uninfected men. This difference suggests that the fate of L-arginine as a substrate for nitric oxide generation may be altered in HIV infected individuals. Subsequently this is likely to escalate endothelial dysfunction, contributing to later hypertension and cardiovascular disease. Our findings show that while glomerular filtration rate is not associated with L-arginine in uninfected men, it is diminished and significantly negatively associated with serum L-arginine in HIV infected men.

Asymmetric dimethylarginine as an independent risk marker for mortality in ambulatory patients with peripheral arterial disease.

BACKGROUND: Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) synthesis causing endothelial dysfunction, an early sign of atherogenesis. Symmetric dimethylarginine (SDMA) does not inhibit NO synthases. Peripheral arterial disease (PAD) is a systemic indication of atherosclerosis. METHODS: We assessed the associations between both ADMA and SDMA blood levels and major cardiovascular and cerebrovascular events or death from any cause within a 5-year follow-up in the multicentre getABI trial. From a cohort of 6821 primary care patients, aged ≥65 years, all 1260 patients with prevalent PAD were compared with a random sample of 1187 non-PAD controls. A total of 11,544 patient-years were documented. Multivariate risks were calculated by Cox proportional hazard models, adjusting for PAD, renal dysfunction and other important cardiovascular risk factors. RESULTS: We documented 390 deaths, 296 cardiovascular events and 98 cerebrovascular events. Increased ADMA levels in the 4th quartile were significantly associated with total mortality [hazard ratio (HR) 1.41; 95% CI 1.14-1.74] and with cardiovascular events (HR 1.32; 95% CI 1.03-1.69), but there was a nonsignificant association with cerebrovascular events (HR 1.50; 95% CI 0.98-2.29). Increased SDMA was only just significantly associated with mortality (HR 1.27; 95% CI 1.01-1.59). In PAD patients compared with non-PAD controls, only mean SDMA concentration was considerably increased (0.52 µmol L(-1) vs. 0.48 µmol L(-1); P < 0.001) mainly because of a highly significant association with impaired renal function. CONCLUSION: These data suggest that ADMA but not SDMA is an independent risk marker for death from any cause or from cardiovascular events. The association between SDMA and mortality is in part explained by a close link between SDMA and renal function.

Redox-generated isoprostanes are associated with residual platelet activity in aspirin-treated patients with stable coronary heart disease.

AIM: Insufficient platelet inhibition by low-dose aspirin is associated with poor prognosis in patients with coronary heart disease (CHD). We sought to investigate the prevalence of this phenomenon in patients with stable CHD and to study whether oxidative stress plays a role in its pathogenesis. METHODS AND RESULTS: We studied the platelet response to long-term (≥ 6 months) low-dose (100 mg per day) aspirin in 130 consecutive patients with stable CHD (age 66 ± 8 years, 83% male). Among a wide distribution of platelet responses to collagen, ADP, and arachidonic acid, the vast majority of patients in the highest tertile of residual platelet activity (defined as 'aspirin low-responders') were characterized by lack of platelet inhibition by aspirin in vitro, significantly although not completely suppressed platelet TXB2 production and COX-1 activity, and significantly higher urinary 8-iso-prostaglandin F(2α) excretion [186 (147-230) vs. 230 (188-318) pg per mg creatinine; median (IQR), P < 0.001; measured by GC-MS]. CONCLUSION: A relevant proportion of patients with CHD show insufficient platelet inhibition by low-dose aspirin. Oxidative stress and lipid peroxidation causing isoprostane formation may underlie inadequate platelet inhibition in an aspirin-insensitive manner in patients with cardiovascular disease.

Interaction of angiotensin receptor type 1 blockers with ATP-binding cassette transporters.

ATP-binding cassette (ABC)-transporters, such as P-glycoprotein (P-gp/ABCB1), multidrug resistance-associated proteins (MRPs/ABCCs) and breast cancer resistance protein (BCRP/ABCG2) transport numerous drugs thus regulating their absorption, distribution and excretion. Angiotensin receptor type 1 blockers (ARBs), used to treat hypertension and heart failure, are commonly administered in combination therapy. However, their interaction potential is not well studied and their effect on ABC-transporters remains elusive. The study therefore aimed to elucidate the effect of various ARBs (telmisartan, candesartan, candesartan-cilexetil, irbesartan, losartan, olmesartan, olmesartan-medoxomil, eprosartan) on ABC-transporter activity in vitro. P-gp inhibition was assessed by calcein assay, BCRP inhibition by pheophorbide A efflux assay, and MRP2 inhibition by a MRP2 PREDIVEZ Kit. Induction of P-gp, BCRP and MRP2 was assessed by real time reverse transcriptase polymerase chain reaction and for P-gp also in a functional assay. Telmisartan was identified as one of the most potent inhibitors of P-gp currently known (IC(50)=0.38+/-0.2 microM for murine P-gp) and it also inhibited human BCRP (IC(50)=16.9+/-8.1 microM) and human MRP2 (IC(50)=25.4+/-0.6 microM). Moreover, the prodrug candesartan-cilexetil, but not candesartan itself, significantly inhibited P-gp and BCRP activity. None of the compounds tested induced mRNA transcription of P-gp or BCRP but eprosartan and olmesartan induced MRP2 mRNA expression. In conclusion, telmisartan substantially differed from other ARBs with respect to its potential to inhibit ABC-transporters relevant for drug pharmacokinetics and tissue defense. These findings may explain the known interaction of telmisartan with digoxin and suggest that it may modulate the bioavailability of drugs whose absorption is restricted by P-gp and possibly also by BCRP or MRP2.

Clinical trial investigating success rates for polyether and vinyl polysiloxane impressions made with full-arch and dual-arch plastic trays.

STATEMENT OF PROBLEM: Success rates for making fixed prosthodontic impressions based on material and tray selection are not known. PURPOSE: The purpose of this clinical study was to compare first impression success rates for 2 types of impression material and 2 impression tray systems. MATERIAL AND METHODS: Dual-viscosity impressions were made with a vinyl polysiloxane (VPS) (Aquasil Ultra Monophase/Aquasil Ultra XLV) and a polyether (PE) (Impregum Penta Soft HB/Impregum Garant Soft LB) impression material. The first impression made was evaluated for success or failure using developed criteria. Fifty senior dental students participated. The type of impression material alternated for each new patient. A full-arch perforated plastic (President Tray) or a plastic dual-arch impression tray (Tri-Bite) was used based on clinical guidelines. Impression success rates were compared using logistic regression, fitted using the method of generalized estimating equations (alpha=.05). RESULTS: One hundred ninety-one impressions were evaluated, and the overall success rate was 61% for VPS and 54% for PE (P=.39). Additional regression analyses, adjusted for potential confounders, did not indicate a difference between the 2 systems (P=.35). There was little difference in success rates between the 2 materials when a full-arch tray was used (50% versus 49% success, P=.89), whereas a larger difference was apparent with the use of dual-arch trays (70% success with VPS versus 58% success with PE, P=.21). The most common critical defect was located on the preparation finish line (94%), and the most common operator error was inadequate gingival displacement (15%). CONCLUSIONS: There was little difference in success rates between VPS and PE when full-arch impression trays were used, but there was greater success when using VPS with dual-arch trays. For single teeth, the trend favored VPS, but when more than one prepared tooth per impression was involved, the success rate was higher for PE.

Increased urinary excretion of 8-iso-prostaglandin F2alpha in patients with HFE-related hemochromatosis: a case-control study.

The hypothesis according to which iron overload could be harmful has been extensively and controversially discussed in the literature. One underlying pathological mechanism may be elevated oxidative stress. Thus, we studied the correlation between hemochromatosis and an established marker of oxidative stress, 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha, iPF2alpha-III, 15-F2t-IsoP). We enrolled 21 patients with hemochromatosis, positive for the homozygous C282Y mutation in the HFE gene, and 21 healthy controls frequency-matched by age and gender in a case-control study design. The objective was to show that iron overload in HFE-related hemochromatosis is associated with increased oxidative stress assessed through 8-iso-PGF(2alpha) urinary excretion, and that oxidative stress is impacted by iron-removal treatment (phlebotomy). Study parameters were transferrin saturation, 8-iso-PGF(2alpha) urine excretion, transferrin, ferritin, serum iron, and vitamins A and E for all participants. Iron concentration in the liver and non-transferrin-bound iron were measured in patients only. We found a significant difference in 8-iso-PGF2alpha in patients (245 [interquartile range 157-348] pg/mg creatinine) compared with controls (128 [106-191] pg/mg creatinine, P = 0.002). Vitamin A was significantly reduced in cases (0.34 [0.25-1.83] microg/ml compared to 3.00 [2.11-3.39] microg/ml, P < 0.001), while vitamin E did not show a significant difference in cases (14.7 [11.5-18.1] microg/ml) compared with controls (14.9 [13.1-19.2] microg/ml, P = 0.52). After phlebotomy treatment and normalization of the iron parameters in the hemochromatosis group, serum vitamin A levels were significantly increased (1.36 [1.08-1.97] microg/ml, P = 0.035 vs. baseline, P < 0.001 vs. controls) and 8-iso-PGF2alpha urinary excretion was lowered to control levels (146 [117-198] pg/mg creatinine, P = 0.38 vs. controls). In our study, HFE-related hemochromatosis was associated with increased oxidative stress and hypovitaminemia A in C282Y homozygotes. The increased oxidative stress was reversible by normalization of the iron load by phlebotomy. Thus, phlebotomy is an effective and adequate means for reducing oxidative stress in these patients.

Direct technique for the fabrication of acrylic provisional restorations.

Provisional restorations are fabricated to protect the prepared tooth structure during the period between tooth preparation and insertion of the definitive restoration. These restorations are also referred to in the literature as interim, temporary, or provisional restorations (prostheses). Such restorations should be uncomplicated and inexpensive to fabricate in a short period of time. Several laboratory and clinical techniques for the fabrication of provisional restorations have been described in the literature, such as the indirect technique, direct technique, and indirect-direct techniques for both single and multiple unit restorations. This article describes a step by step clinical technique for the fabrication of a direct provisional restoration to satisfy the issues of esthetics, patient comfort, speech and function, maintenance of periodontal health, and maxillomandibular relationships while wearing the restoration.

A technique for locating implant abutment screws of posterior cement-retained metal-ceramic restorations with ceramic occlusal surfaces.

With the increased use of cement-retained implant-supported restorations for the replacement of missing teeth, clinicians may choose to use a definitive cement to lute the definitive restoration. A complication that may occur, especially for a single-tooth replacement, is loosening of the abutment screw. In those situations, it may be difficult to locate the abutment-screw access to remove the restoration. The purpose of this article is to describe a technique that may facilitate the clinician's ability to locate the abutment-screw access in the event of abutment-screw loosening, thus reducing the need for refabricating the restoration.

Determination of a reference value for N(G), N(G)-dimethyl-L-arginine in 500 subjects.

BACKGROUND: Asymmetric dimethylarginine (ADMA) acts as an endogenous inhibitor of NO-synthase. In the last years ADMA has emerged as a cardiovascular risk factor. The aim of this study was to determine a reference value for ADMA. METHODS: Plasma samples of 500 healthy subjects in the 19-75 year age group were analyzed. Exclusion criteria from this study were smoking, any known significant disease, body-mass-index (BMI) above 30 kg m(-2), elevated plasma lipid levels, impaired renal function, hypertension, and intake of any medication. The ADMA levels were determined by ELISA, (DLD Diagnostics, Hamburg, Germany). RESULTS: Mean ADMA plasma concentration of the total population was 0.69 micromol L(-1) (SD 0.20) and 95% of the measured values were in the range from 0.36 micromol L(-1) to 1.17 micromol L(-1). Women below 50 years of age had lower ADMA levels than men below 50 years of age [0.62 (0.17) micromol L(-1) vs. 0.69 (0.19) micromol L(-1); P = 0.001] and woman above 50 years of age had higher ADMA levels than men above 50 years of age [0.80 (0.22) micromol L(-1) vs. 0.73 (0.20) micromol L(-1); P = 0.036]. A regression analysis of ADMA levels and age was performed for each sex. The regression factor was r = 0.444 for women in a squared regression model (P < 0.001) and r = 0.212 for men in a linear regression model (P < 0.001). CONCLUSION: The study was able to define a reference value for ADMA plasma levels with 0.36-1.17 micromol L(-1) and found sex dependent correlations between ADMA and age. Women showed a significant increase in ADMA plasma levels with onset of menopause.

[Biomarkers as prognostic factors in pulmonary arterial hypertension. Rationale and study design]. / Evaluation pronostique de biomarqueurs dans l'hypertension artérielle pulmonaire. Justification et plan expérimental.

CURRENT SITUATION: Pulmonary arterial hypertension (PAH) is a serious disease. Its prognostic is based on the functional status quantified by the NYHA class and the 6-min walking test, and the hemodynamic data. The algorithms of treatment are solely based on the hemodynamic data and the functional status. The main objective is to test whether basal concentrations of isoprostanes, Big endotheline 1, ADMA, high sensitivity CRP, NT-Pro-BNP and cardiac troponin T are a 3-year prognostic factor in PAH using a combined criterion: death from any cause and pulmonary or cardiopulmonary transplantation. MATERIALS AND METHODS: This is a multicenter, prospective, prognostic, single blinded study (plasma and urinary samples being blinded). The study started in november 2003, running for 2 years, with a 3 year follow-up for each patient. The main inclusion criterion is PAH. The data analysis will use a multivariable Cox model, taking into account the functional and hemodynamic parameters. EXPECTED RESULTS: This study will determine whether any of the biomarkers tested provides additional prognostic information in PAH in addition to the functional and hemodynamic parameters.

A crown venting technique for the cementation of implant-supported crowns.

With the increased use of implant systems for the replacement of single teeth, some dental practitioners are choosing to permanently cement the final restoration instead of using the screw-retention modality. Many of these restorations have subgingival margins; therefore, the cementation technique becomes a critical procedure because incomplete seating of the restoration or excess cement can be lodged in the gingival sulcus. The use of a cement escape way or venting technique for the cementation of an implant-supported restoration is described.

Normal oxidative stress and enhanced lipoprotein resistance to in vitro oxidation in hypertriglyceridemia: effects of bezafibrate therapy.

Although there is evidence that hyperlipidemia and predominance of small dense low density lipoproteins (LDLs) are associated with increased oxidative stress, the oxidation status in patients with hypertriglyceridemia (HTG) has not been studied in detail. Therefore, we studied urinary levels of F(2)-isoprostanes (8-isoprostaglandin F(2alpha) and 2,3-dinor-5,6-dihydro-8-isoprostaglandin F(2alpha)) and susceptibility of very low density lipoproteins (VLDLs) and LDLs to oxidation ex vivo in 18 patients with endogenous HTG and 20 matched control subjects. In addition, the effects of 6 weeks of bezafibrate therapy were assessed in a double-blind, placebo-controlled, crossover trial. Urinary levels of F(2)-isoprostanes were similar in the HTG and normolipidemic group. Bezafibrate caused an increase in 8-isoprostaglandin F(2alpha) (762+/-313 versus 552+/-245 ng/24 h for bezafibrate and placebo therapy, respectively; P=0.03), whereas 2,3-dinor-5, 6-dihydro-8-isoprostaglandin F(2alpha) levels tended to be increased (1714+/-761 versus 1475+/-606 ng/24 h for bezafibrate and placebo therapy, respectively; P=0.11). VLDLs and LDLs were more resistant to copper-induced oxidation in patients with HTG than in control subjects. Bezafibrate reversed the oxidation resistance to the normal range. In conclusion, these results indicate the following: (1) HTG is associated with normal in vivo oxidative stress and enhanced ex vivo resistance of lipoproteins to oxidation. (2) Bezafibrate reduces the resistance of lipoproteins to copper-induced oxidation and enhances oxidative stress in HTG patients.

Tandem mass spectrometric quantification of 8-iso-prostaglandin F2alpha and its metabolite 2,3-dinor-5,6-dihydro-8-iso-prostaglandin F2alpha in human urine.

Whole body synthesis of F2-isoprostanes, a family of cyclooxygenase-independent eicosanoids formed by free-radical catalysed peroxidation, should be best assessed by quantifying their urinary metabolites. Two methods for the quantitative determination of F2-isoprostane metabolites in human urine performing either thin-layer chromatography (TLC) (method A) or high-performance liquid chromatography (HPLC) (method B) prior to GC-tandem MS are described. Method A allows for simultaneous quantification of 8-iso-PGF2alpha, one prominent member of the F2-isoprostane family, and its major urinary metabolite, 2,3-dinor-5,6-dihydro-8-iso-PGF2alpha. Mean excretion was found to be 223 and 506 pg/mg creatinine of 8-iso-PGF2alpha and 2,3-dinor-5,6-dihydro-8-iso-PGF2alpha, respectively (n=14). A tight correlation existed between the urinary excretion of these two isoprostanes (r=0.86). Method B enables quantification of dinor-dihydro metabolites of various F2-isoprostanes including 8-iso-PGF2alpha. 2,3-Dinor-5,6-dihydro-8-iso-PGF2alpha was found to be an abundant dinor-dihydro F2-isoprostane metabolite. Validity of method A was proven by a combination of HPLC with TLC prior to GC-tandem MS analysis. A correlation was observed between the urinary concentrations of 2,3-dinor-5,6-dihydro-8-iso-PGF2alpha measured by GC-MS and GC-tandem MS (r=0.84).

Nebivolol decreases systemic oxidative stress in healthy volunteers.

AIMS: Nebivolol is a selective, vasodilatory beta1-adrenergic receptor antagonist which has been suggested to possess additional antioxidative properties. The aim of the present study was to assess the actions of nebivolol in antihypertensive doses on systemic oxidative stress in healthy volunteers, reflected by 24 h urinary excretion of 8-iso-PGF2alpha. METHODS: In a double-blind, cross-over study, 12 healthy volunteers received 5 mg nebivolol once daily or placebo for a total of 7 days, separated by a wash out period of 2 weeks. After each treatment period 24 h urinary excretion of 8-iso-PGF2alpha was determined by gas chromatography-tandem mass spectrometry. RESULTS: After the 7 day treatment period nebivolol decreased significantly urinary excretion of 8-iso-PGF2alpha by 24% from 55.3 +/- 5.1 pmol mmol-1 creatinine during the placebo period to 42.3 +/- 4.7 pmol mmol-1 creatinine (mean +/- s.e. mean, P = 0. 01), a mean decrease of 13 pmol mmol-1 creatinine (95% CI: -22.8; -3. 1). CONCLUSIONS: Our data show for the first time that nebivolol decreases systemic oxidative stress in young healthy volunteers.

Gas chromatographic-tandem mass spectrometric quantification of free 3-nitrotyrosine in human plasma at the basal state.

A fully validated gas chromatographic-tandem mass spectrometric (GC-tandem MS) method for the accurate and precise quantification of free 3-nitrotyrosine in human plasma at the basal state is described. In the plasma of 11 healthy humans a mean concentration of 2.8 nM (range 1.4-4.2 nM) for free 3-nitrotyrosine was determined by this method. This is the lowest concentration reported for free 3-nitrotyrosine in plasma of healthy humans. The presence of endogenous free 3-nitrotyrosine in human plasma was unequivocally shown by generating a daughter mass spectrum. Various precautions had to be taken to avoid artifactual formation of 3-nitrotyrosine from nitrate during sample treatment. Endogenous plasma 3-nitrotyrosine and 3-nitro-l-[(2)H(3)]tyrosine added for use as internal standard were isolated by high-performance liquid chromatographic (HPLC) analysis of 200-microl aliquots of plasma ultrafiltrate samples (20 kDa cut-off), extracted from a single HPLC fraction by solid-phase extraction, derivatized to their n-propyl ester-pentafluoropropionyl amide-trimethylsilyl ether derivatives, and quantified by GC-tandem MS. Overall recovery was determined as 50 +/- 5% using 3-nitro-l-[(14)C(9)]tyrosine. The limit of detection of the method was 4 amol of 3-nitrotyrosine, while the limit of quantitation was 125 pM using 3-nitro-l-[(14)C(9)]tyrosine. 3-Nitrotyrosine added to human plasma at 1 nM was quantitated with an accuracy of > or = 80% and a precision of > or = 94%. The method should be useful to investigate the utility of plasma free 3-nitrotyrosine as an indicator of nitric oxide ((.)NO)-associated oxidative stress in vivo in humans.