Baseline Plasma Concentrations Research Articles

Comparison of the Systemic Levels of Inflammatory Markers after Percutaneous Coronary Intervention with Bare Metal versus Sirolimus‐Eluting Stents

Percutaneous coronary intervention (PCI) with bare metal stent (BMS) deployment causes plaque disruption and a rise in systemic levels of C-reactive protein (CRP), interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1. Our aim is to study whether PCI with sirolimus-eluting stent (SES) use attenuates this response. Patients with stable angina undergoing single-vessel PCI were enrolled in a randomized, open-label fashion into a BMS group or an SES group. Blood samples were drawn pre-PCI, 24 hours post-PCI, and 30 days post-PCI. Systemic concentrations of CRP, IL-6, and MCP-1 were measured at all time points. In total, 41 patients were enrolled (21 in the BMS group and 20 in the SES group). The baseline plasma concentrations of all markers were comparable between groups. At 24 hours, the mean plasma CRP concentration in the SES group was 20.21 mg/dL versus 8.95 mg/dL in the BMS group (P = 0.15). The mean plasma IL-6 concentration at 24 hours was 25.41 pg/mL in the SES group versus 17.44 pg/mL in the BMS group (P = 0.17). The mean plasma MCP-1 concentration at 24 hours was 382.38 pg/mL in the SES group versus 329.04 pg/mL in the BMS group (P = 0.2). At 30 days, plasma concentrations of all three markers decreased to similar values between groups. The use of SES did not inhibit the rise in systemic concentrations of CRP, IL-6, and MCP-1 at 24 hours or 30 days post-PCI, compared with BMS. Moreover, at 24 hours, there was a trend for higher systemic levels of all proinflammatory markers in the SES group compared with the BMS cohort.

Serum concentration/dose ratio of topiramate during pregnancy

To study the impact of pregnancy on the serum concentration/dose ratio (C/D-ratio) of topiramate (TPM). Twelve women with epilepsy using TPM during pregnancy, and 15 pregnancies were studied. The main target variable was the C/D-ratio at baseline and during pregnancy. Additional variables were changes in TPM dose, concomitant use of other antiepileptic drugs, seizure frequency, and pregnancy outcome. Clinical and pharmacological data were obtained from the women's medical records. The average C/D-ratios in the second and third trimester were 30% (p = 0.002, n = 11) and 34% (p = 0.001, n = 8) lower than the baseline values, respectively. The interindividual variability was pronounced. Increased seizure frequency was common in pregnant women using TPM, but a correlation to the decline in TPM C/D-ratio could not be established from our data. Dose-corrected serum concentrations of TPM appear to decline gradually throughout pregnancy. The underlying mechanisms are not known. Increased glomerular filtration may play a major role. During pregnancy, therapeutic drug monitoring of TPM may be useful.

Abstract 2120: Circulating Markers of Myocyte Injury Predict First Recurrence of Atrial Fibrillation. Data from the GISSI-Atrial Fibrillation Trial

Whether circulating biomarkers may help in predicting long-term maintenance of sinus rhythm in patients with atrial fibrillation (AF) is still debated. We evaluated the prognostic role of two markers of cardiomyocyte injury in patients with a history of recent AF. Baseline plasma concentrations of NT-proBNP and cardiac troponin T (high sensitive, for evaluation purposes only) were measured (Elecsys 2010, Roche Diagnostics) in 382 patients diagnosed with symptomatic AF having additional underlying cardiovascular diseases/comorbidities, enrolled in 36 centers participating to GISSI-AF, a prospective randomized study. The association between these markers, clinical characteristics and outcome (adjudicated primary endpoint: time to first recurrence of AF) was tested by univariate and multivariable Cox models. Baseline concentrations of NT-proBNP and hsTnT were 191 [95–363] pg/mL (median [Q1–Q3]) and 0.008 [0.006 – 0.013] ng/mL in these patients with a history of AF (62.8% males, 46.1% aged > 70 y, 11% with either HF or depressed LVEF, 13.1% diabetics, 33.3% with SBP >140 mmHg ). Both markers were elevated in older patients (>70 y), those with HF and/or LVEF<0.40 or with creatinine >1 mg/dL. Above median concentrations of hsTnT (HR [95%CI] adjusted for gender 1.35 [1.02–1.78], p=0.038) and NT-proBNP (1.34 [1.01–1.78], p=0.040) were associated with higher risk of experiencing a first recurrence of AF (203 patients, 53.1%). Even small elevations of circulating markers of cardiomyocyte death (troponin) and stretch (natriuretic peptide) may be useful for the prediction of recurrence of AF in patients with a history of recent AF.

Metalloproteinase Expression in Carotid Plaque and Its Correlation With Plasma Levels Before and After Carotid Endarterectomy

To assess baseline and follow-up plasma concentrations of metalloproteinase-9 (MMP-9), MMP-2, and tissue inhibitor of metalloproteinase-2 (TIMP-2) in patients undergoing carotid thromboendarterectomy (TEA) in relation to tissue expression and diagnostic features. Using sandwich enzyme-linked immunosorbent assay, plasma levels of enzymes were determined in 15 patients undergoing carotid TEA. Tissue sections were incubated with specific antibodies and fluorescence intensity was analyzed. MMP-9 levels were higher in patients with carotid stenosis versus controls, significantly in those with cerebral lesions at neuroimaging. MMP-9 levels decreased in 93.4% of the patients at 1 month. MMP-2 levels tended to increase 30 days after surgery. TIMP-2 showed no difference. High concentrations of MMP-9 found in patients with carotid stenosis and cerebral lesions suggest that MMP-9 assay could be useful in the evaluation of all carotid lesions to help identify those at highest risk of a neurologic event.

Depletion of plasma antioxidants in surgical intensive care unit patients requiring parenteral feeding: effects of parenteral nutrition with or without alanyl-glutamine dipeptide supplementation

Objectives Antioxidant depletion is common in critically ill patients. This study was designed to determine the effects of parenteral nutrition (PN), with or without glutamine (Gln) supplementation, on systemic antioxidant status in adult patients after major surgery who required PN in the surgical intensive care unit (SICU) setting. Methods Fifty-nine patients in the SICU who required PN after pancreatic surgery or cardiac, vascular, or colonic (non-pancreatic) surgery were randomized in a double-blinded study to receive standard PN (Gln-free) or Gln-supplemented PN (Gln-PN) in which Gln was provided as alanyl-Gln dipeptide. Conventional PN vitamin and mineral doses were administered to all subjects. Plasma concentrations of the antioxidant glutathione (GSH) and the antioxidant nutrients α-tocopherol, vitamin C, and zinc were determined at baseline (initiation of study PN) and again after 7 d of study PN. Data were analyzed for the total study cohort and within the pancreatic surgery and non-pancreatic (cardiac, vascular, and colonic) surgery patient subgroups. Results Mean plasma antioxidant concentrations were within or slightly below the normal ranges at baseline. However, a larger percentage of patients demonstrated below-normal baseline plasma concentrations of GSH (59%), vitamin C (59%), and zinc (68%), respectively. A smaller percentage of patients exhibited below-normal plasma α-tocopherol levels (21%). Study PN significantly improved plasma zinc levels in the entire study group and in each surgical subgroup. Gln-PN significantly improved the change in plasma levels of reduced GSH from baseline to day 7 in the non-pancreatic surgery patients (PN −0.27 μM versus Gln-PN +0.26 μM, P < 0.03). Conclusion Low plasma levels of key antioxidants were common in this group of patients in the SICU despite administration of PN containing conventional micronutrients. Compared with standard PN, Gln-supplemented PN improved plasma GSH levels in patients in the SICU after cardiac, vascular, or colonic operations.

Sympathoadrenal function in patients with paroxysmal hypertension: pseudopheochromocytoma

The causes of paroxysmal hypertension in patients in whom pheochromocytoma has been excluded ('pseudopheochromocytoma') usually remain unclear. Blood pressure disturbances and symptoms of catecholamine excess in these patients may reflect activation of the sympathetic nervous and adrenal medullary systems. We therefore examined sympathoadrenal function in patients with pseudopheochromocytoma compared with age-matched control subjects in whom there was no suspicion of pheochromocytoma. Plasma catecholamines and hemodynamics were examined in response to intravenous glucagon, yohimbine, and trimethaphan in 11 patients with pseudopheochromocytoma and a comparison group of nine normotensive and five hypertensive volunteers. Adrenomedullary function was also assessed by abdominal F-fluorodopamine positron emission tomography and measurements of plasma metanephrine, the O-methylated metabolite of epinephrine. Compared with controls, patients with pseudopheochromocytoma had normal plasma concentrations of norepinephrine, but 120% higher (P < 0.05) baseline plasma concentrations of epinephrine, 80% higher (P < 0.01) baseline plasma concentrations of metanephrine, and sixfold larger (P < 0.05) increases in plasma epinephrine after glucagon. Adrenal 18F-fluorodopamine-derived radioactivity did not differ between groups. Compared with changes in plasma norepinephrine, falls in blood pressure after trimethaphan were 13-fold larger (P < 0.005) and increases in blood pressure after yohimbine were threefold larger (P < 0.01) in pseudopheochromocytoma patients than in controls. Patients with pseudopheochromocytoma exhibit a pattern of normal sympathetic noradrenergic outflow, adrenomedullary activation, and augmented blood pressure responses to changes in the sympathoneural release of norepinephrine.

Quantitation of hepcidin from human and mouse serum using liquid chromatography tandem mass spectrometry

AbstractThe hepatic peptide hormone hepcidin is considered the central regulator of iron metabolism. Characterizing the circulating levels of this peptide is critical to understanding its role in the development of clinically relevant syndromes, such as anemia of inflammation/chronic disease, and may provide insight into potential clinical interventions. While quantitative methods have been published for the determination of urinary hepcidin and serum prohepcidin, no definitive methods have been published for the determination of hepcidin in serum. In this report, we describe a quantitative method for the determination of both human and mouse hepcidin in serum and plasma. The method employs protein precipitation and solid-phase extraction followed by liquid chromatographic separation and tandem mass spectrometry detection. The method has a quantitative range of 0.25 ng/mL to 500 ng/mL serum for mouse hepcidin and 1 ng/mL to 500 ng/mL serum for human hepcidin. The method uses small sample volumes (50 μL for mice and 100 μL for humans) and 96-well formats for rapid sample processing. The method was used to establish baseline serum and plasma concentrations of hepcidin in normal C57Bl/6 mice and healthy human volunteers.

Prognostic importance of plasma NT‐pro BNP in chronic heart failure in patients treated with a β‐blocker: Results from the Carvedilol Or Metoprolol European Trial (COMET) trial

Plasma levels of N-terminal pro-brain natriuretic peptide (NT-pro BNP) are increased in patients with chronic heart failure (CHF). Beta-blockers (BB) may influence these levels but it is unclear whether changes in NT-pro BNP reflect concomitant changes in prognosis. To assess the prognostic importance of NT-pro BNP at baseline and during follow-up, in patients in whom beta-blocker therapy is initiated. In COMET, 3029 patients with CHF in NYHA class II-IV and EF<35% were randomised to carvedilol or metoprolol tartrate and were followed for an average of 58 months. Blood samples were collected for the measurement of NT-pro BNP at baseline (n=1559) and during follow-up (n=309). Baseline plasma concentrations of NT-pro BNP above the median (1242 pg/ml) were associated with higher all-cause mortality (RR 2.77; 95% CI 2.33-3.3, p<0.001). Patients who achieved NT-pro BNP levels<400 pg/ml during follow-up had a lower subsequent mortality (RR 0.32; 95% CI 0.15-0.69, p=0.004). The plasma concentration of NT-pro BNP is a powerful predictor of mortality in patients with CHF. Patients who achieve an NT-pro BNP of <400 pg/ml subsequent to treatment with a beta-blocker have a favourable prognosis.

Markers of inflammation and cognitive decline in an African‐Caribbean population

Inflammatory processes may play an important role in cognitive decline and dementia. We investigated the prospective association between levels of three markers of inflammation, plasma interleukin-6 (IL-6), serum C-reactive protein (CRP), serum amyloid A (SAA), and cognitive decline in an African-Caribbean community population. Of 290 participants aged 55-75 years at baseline sampled from Primary Care registration lists in south London, 216 (75%) were re-interviewed after 3 years. Baseline plasma concentrations of IL-6, CRP and SAA were ascertained through immunoassays. A battery of psychometric tests was administered on both occasions and decline in both individual tests and a composite outcome was analysed. After adjustment for potential confounding factors, raised levels of IL-6 (>3.1 pg/ml) were associated with cognitive decline in the total sample (odds ratio 2.9, 95% CI 1.1-7.5), but no associations were found for CRP or SAA. Raised IL-6 was most strongly associated with decline in orientation and immediate verbal recall tasks, with weaker associations for delayed recall and psychomotor speed. Raised IL-6 but not CRP predicted cognitive decline in this population Inflammatory changes associated with cognitive decline may be specific to particular causal pathways.

Antioxidant supplementation does not affect fasting plasma glucose in the Supplementation with Antioxidant Vitamins and Minerals (SU.VI.MAX) study in France: association with dietary intake and plasma concentrations 1–3

Observational data suggest a protective effect of several antioxidants on fasting plasma glucose (FPG) and type 2 diabetes. However, randomized trials have yielded inconsistent results. The first objective was to assess the effect of 7.5 y of antioxidant supplementation on FPG at 7.5 y. The second objective was to examine the epidemiologic association of baseline dietary intakes or plasma antioxidants and FPG (at baseline and at 7.5 y). Subjects (n = 3146) from the Supplementation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) primary prevention trial in France were randomly assigned to receive a daily capsule containing 120 mg vitamin C, 30 mg vitamin E, 6 mg beta-carotene, 100 mug Se, and 20 mg Zn or a placebo. After 7.5 y, no significant difference was observed between age-adjusted mean FPG in men (P = 0.78) and women (P = 0.89) in either group. Baseline beta-carotene dietary intakes and plasma concentrations were inversely associated with FPG in multivariate mixed models (P = 0.0045 and P < 0.0001, respectively). Baseline plasma vitamin C and selenium were negatively (P = 0.0455) and positively (P < 0.0001) associated, respectively, with FPG. Supplementation with antioxidants at nutritional doses for 7.5 y had no effect on FPG in men or women who followed a balanced diet. An inverse association of baseline beta-carotene dietary intake and plasma concentrations with FPG was found, probably because beta-carotene is an indirect marker of fruit and vegetable intakes.

Serum adiponectin levels and enzyme markers of liver dysfunction in diabetic and non-diabetic Caribbean subjects

Low adiponectin levels are associated with elevated plasma alanine aminotransferase, a marker of reduced hepatic insulin sensitivity and a risk factor for type 2 diabetes. This study aims to determine the relationship between serum adiponectin level and alanine aminotransferase in diabetic and non-diabetic subjects. Fifty-six type 2 diabetic patients and 33 non-diabetic subjects participate in the study. Baseline plasma concentrations of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and glucose are measured on a chemistry analyser. Insulin and adiponectin are measured using enzyme-linked immunoassay techniques and insulin resistance is determined using the homeostatic model assessment method. Diabetic patients showed significantly lower levels of serum adiponectin than did the non-diabetic subjects, whereas levels of alanine aminotransferase and alkaline phosphatase were similar in both groups. While female non-diabetic subjects showed higher serum adiponectin levels than did female diabetic patients, alanine aminotransferase level did not differ (P>0.05). No significant relationship was seen between adiponectin and alanine aminotransferase in diabetic and non-diabetic subjects (P>0.05). Serum adiponectin levels were higher in non-diabetic subjects but there was no significant correlation between adiponectin and alanine aminotransferase in both groups of subjects. The data suggest that low serum adiponectin level may not be a suitable marker for impaired liver function in diabetic patients.

Use of the plasma stromelysin (matrix metalloproteinase 3) concentration to predict joint space narrowing in knee osteoarthritis

To determine whether baseline or serial plasma concentrations of stromelysin (matrix metalloproteinase 3 [MMP-3]) protein might distinguish subjects with progressive radiographic knee osteoarthritis (OA) from those with stable disease. Subjects were 120 women with unilateral knee OA who participated in a 30-month randomized, placebo-controlled trial of structure modification with doxycycline. Anteroposterior views of both knees in a semiflexed position were obtained at baseline, 16 months, and 30 months. Subjects were selected to obtain comparisons of plasma MMP-3 levels between 60 progressors (21 taking doxycycline, 39 taking placebo) and 60 nonprogressors (30 taking doxycycline, 30 taking placebo) with respect to medial joint space narrowing (JSN) in the index knee. Each group consisted of 30 subjects who exhibited significant increases in knee pain. Blood samples were obtained semiannually for MMP-3 assay. Subjects in the placebo group whose MMP-3 concentration was in the upper tertile of the baseline distribution showed a 4-fold increase in the odds of progression of JSN as compared with the lower tertile (odds ratio 4.12, P = 0.037). Baseline MMP-3 levels were unrelated to knee pain. The within-subject mean of serial MMP-3 concentrations was associated with concurrent JSN in the placebo group over the 0-16-month interval (b = 0.18 mm/SD increase in the mean MMP-3, P < 0.01) and over the 16-30-month interval (b = 0.15, P < 0.05). Similar evidence of concurrent validity was found in the placebo group for the maximum of intercurrent MMP-3 values. The baseline MMP-3 level was a significant predictor of JSN in this pilot study. Moreover, serial plasma MMP-3 levels reflected concurrent JSN in the placebo group over the 30-month period of observation.

Plasma appearance of labeled β-carotene, lutein, and retinol in humans after consumption of isotopically labeled kale

The bioavailability of carotenoids from kale was investigated by labeling nutrients in kale with 13C, feeding the kale to seven adult volunteers, and analyzing serial plasma samples for labeled lutein, beta-carotene, and retinol. Ingested doses of labeled carotenoids were 34 micromol for beta-carotene and 33 micromol for lutein. Peak plasma concentrations, areas under the plasma concentration-time curves (AUCs), and percentages of dose recovered at peak plasma concentrations were calculated. Average peak plasma concentrations were 0.38, 0.068, and 0.079 microM for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. Average AUC values (over 28 days) were 42.8, 13.6, 13.2 microM h for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. Percentages of dose recovered at peak plasma concentrations were 3.6, 0.7, and 0.7% for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. A positive relationship was observed between baseline plasma retinol levels and [13C]retinol plasma response. It is possible that this relationship was mediated either through some aspect of beta-carotene absorption or via the common pathways of metabolism for postdose and endogenous retinoid.

TAFI gene haplotypes, TAFI plasma levels and future risk of coronary heart disease: the PRIME Study.

To evaluate the association of thrombin-activatable fibrinolysis inhibitor (TAFI) gene polymorphisms with the risk of coronary heart disease (CHD) and with TAFI levels measured by a newly developed enzyme-linked immunosorbent assay (ELISA) (TAFI-1B1), shown to be a reliable method for detecting quantitative variations in circulating TAFI. Six polymorphisms (C-2599G, G-438A, Ala147Thr, Thr325Ile, C + 1542G and T + 1583A) were genotyped and baseline plasma concentrations of TAFI were measured in a nested case-control design as part of the Prospective Epidemiological Study of Myocardial Infarction (PRIME) Study. Participants from France and Northern Ireland who had developed a CHD event during a 5-year follow-up (n = 321) were compared with 645 population- and age-matched control subjects. In France, the Thr147 allele was more frequent in cases than in controls (0.41 vs. 0.32; P = 0.02), whereas the reverse was observed in Northern Ireland (0.33 vs. 0.38; P = 0.19) (P = 0.01 for interaction). No other polymorphism was associated with CHD risk. Consistent with the results derived from the single-locus analysis, haplotype analysis revealed that the haplotype carrying the Thr147 allele was associated with increased risk of CHD in France while the reverse tended to hold in the Northern Ireland population. Single-locus and haplotype analyses revealed that two polymorphisms, C-2599G and Ala147Thr (or T + 1583A that is in nearly complete association with it), had additive effects on TAFI levels and explained >18% of TAFI variability. This effect was homogeneous in France and Northern Ireland, and in cases and controls who exhibited similar TAFI levels. Thrombin-activatable fibrinolysis inhibitor gene polymorphisms are strongly associated to plasma TAFI levels, but the relation to CHD risk is less clear.

Effect of psoriasis treatment on plasma concentrations of metalloproteinase‐1 and tissue inhibitor of metalloproteinases‐1

The aim of this study was to evaluate the effect of psoriasis treatment on plasma concentrations of metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinases-1 (TIMP-1) with respect to disease severity. MMP-1 and TIMP-1 were measured using an enzyme immunoassay in plasma of 32 patients before and after topical treatment. Data were analysed with respect to baseline values of the Psoriasis Area and Severity Index (PASI). Baseline plasma concentrations of both TIMP-1 and MMP-1 (1487 +/- 102 and 21.0 +/- 2.5 ng/mL, respectively) were significantly higher (P = 0.02 and 0.03, respectively) than normal. Both TIMP-1 and MMP-1 decreased significantly after completion of treatment to values similar to normal (1112 +/- 127 and 11.3 +/- 1.3 ng/mL, respectively). There was a significant positive correlation (r = 0.522) between baseline PASI and TIMP-1 values. Significant differences were observed between baseline TIMP-1 concentrations in groups with PASI < 15 and PASI > 20. Baseline values (1697 +/- 162 ng/mL) in patients with severe course of the disease (PASI > 20) were significantly elevated in comparison to normal values. Treatment caused a decrease in TIMP-1 plasma concentrations in all groups, but a significant difference was noted only in patients with pretreatment PASI > 20. Baseline MMP-1 concentrations exceeded significantly normal values only in patients with PASI < 15 (27.2 +/- 6.3 ng/mL) and 15-20 (18.4 +/- 1.4 ng/mL). Treatment caused a significant decrease in MMP-1-values in all groups to levels similar to normal. Our results confirm the role of TIMP-1 and MMP-1 in the pathogenesis of psoriasis. Pretreatment plasma TIMP-1 increased whereas MMP-1 decreased in patients with a more severe course of the disease. However, successful treatment causes normalization of these plasma protein concentrations irrespective of psoriasis baseline activity.

Pharmacokinetics of dexamethasone with pharmacokinetic/pharmacodynamic model of the effect of dexamethasone on endogenous hydrocortisone and cortisone in the horse

A compartmental model was used to describe the pharmacokinetics of dexamethasone (DXM) and changes in the plasma concentration of endogenous cortisone (COR) and hydrocortisone (HYD) following intravenous (i.v.) administration of DXM (0.05 mg/kg) in horses. Quantification of DXM, COR and HYD in equine plasma was achieved using liquid chromatography interfaced with triple spray quadrupole quantum tandem mass spectrometry (LC/TSQ-MS/MS). The median alpha (t(1/2alpha)), beta (t(1/2beta)), and gamma (t(1/2gamma)) half-lives were 0.33, 2.2, and 10.7 h respectively. The area under the DXM plasma concentration curve (AUC) was 113.5 ng.h/mL. At 72 h post-DXM administration, the plasma concentration of DXM in all horses was below the level of quantification (100 pg/mL). The baseline plasma concentration of COR was 3.5 +/- 0.69 ng/mL and declined significantly (P < 0.02) to 2.9 +/- 0.86 ng/mL at 1 h. The nadir in COR plasma concentration was 0.65 +/- 0.12 ng/mL at 28.8 +/- 9.0 h, and the DXM plasma concentration was 0.19 +/- 0.13 ng/mL. COR concentration returned to baseline at 96 h. Baseline plasma concentration of HYD was 58.8 +/- 11.7 ng/mL and declined significantly (P < 0.001) to 41.1 +/- 14.9 ng/mL at 1 h following DXM administration but recovered to baseline at 96 h. The sensitivity of LC/TSQ-MS/MS allowed complete description of the pharmacokinetics of DXM and its effect on plasma concentrations of both COR and HYD.

Metabolic biomarkers of increased oxidative stress and impaired methylation capacity in children with autism

Autism is a complex neurodevelopmental disorder that usually presents in early childhood and that is thought to be influenced by genetic and environmental factors. Although abnormal metabolism of methionine and homocysteine has been associated with other neurologic diseases, these pathways have not been evaluated in persons with autism. The purpose of this study was to evaluate plasma concentrations of metabolites in the methionine transmethylation and transsulfuration pathways in children diagnosed with autism. Plasma concentrations of methionine, S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), adenosine, homocysteine, cystathionine, cysteine, and oxidized and reduced glutathione were measured in 20 children with autism and in 33 control children. On the basis of the abnormal metabolic profile, a targeted nutritional intervention trial with folinic acid, betaine, and methylcobalamin was initiated in a subset of the autistic children. Relative to the control children, the children with autism had significantly lower baseline plasma concentrations of methionine, SAM, homocysteine, cystathionine, cysteine, and total glutathione and significantly higher concentrations of SAH, adenosine, and oxidized glutathione. This metabolic profile is consistent with impaired capacity for methylation (significantly lower ratio of SAM to SAH) and increased oxidative stress (significantly lower redox ratio of reduced glutathione to oxidized glutathione) in children with autism. The intervention trial was effective in normalizing the metabolic imbalance in the autistic children. An increased vulnerability to oxidative stress and a decreased capacity for methylation may contribute to the development and clinical manifestation of autism.

Asymmetric Dimethylarginine, an Endogenous Inhibitor of Nitric Oxide Synthase, Explains the “L-Arginine Paradox” and Acts as a Novel Cardiovascular Risk Factor

There is abundant evidence that the endothelium plays a crucial role in the maintenance of vascular tone and structure. One of the major endothelium-derived vasoactive mediators is nitric oxide (NO). Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of NO synthase. ADMA inhibits vascular NO production in concentrations found in pathophysiological conditions; ADMA also causes local vasoconstriction when it is infused intraarterially. Thus, elevated ADMA levels may explain the "L-arginine paradox," i.e., the observation that supplementation with exogenous L-arginine improves NO-mediated vascular functions in vivo, although its baseline plasma concentration is about 25-fold higher than the Michaelis-Menten constant K(m) of the isolated, purified endothelial NO synthase in vitro. The biochemical and physiological pathways related to ADMA are well understood: Dimethylarginines are the result of degradation of methylated proteins; the methyl group is derived from S-adenosylmethionine. Both ADMA and its regioisomer, symmetric dimethylarginine, are eliminated from the body by renal excretion, whereas only ADMA is metabolized via hydrolytic degradation to citrulline and dimethylamine by the enzyme dimethylarginine dimethylaminohydrolase (DDAH). DDAH activity and/or expression may therefore contribute to the pathogenesis of endothelial dysfunction in various diseases. Plasma ADMA levels are increased in humans with hypercholesterolemia, atherosclerosis, hypertension, chronic renal failure, and chronic heart failure. Increased ADMA levels are associated with reduced NO synthesis as assessed by impaired endothelium-dependent vasodilation. In several prospective and cross-sectional studies, ADMA evolved as a marker of cardiovascular risk. With increasing knowledge of the role of ADMA in the pathogenesis of cardiovascular disease, ADMA is becoming a goal for pharmacotherapeutic interventions. Among other potential strategies that are currently being tested, administration of L-arginine has been shown to improve endothelium-dependent vascular functions in subjects with high ADMA levels. Finally, ADMA has gained clinical importance recently because several studies have shown that ADMA is an independent cardiovascular risk factor.

TLR4/Asp299Gly, CD14/C-260T, plasma levels of the soluble receptor CD14 and the risk of coronary heart disease: The PRIME Study.

TLR4 and CD14 are two components of the LPS receptor complex, which are considered to play a key role in the pathogenesis of atherosclerosis. TLR4/Asp299Gly and CD14/C-260T polymorphisms are thought to modulate the activity of this complex. The aim of the study was to examine the association between the TLR4/Asp299Gly and CD14/C-260T polymorphisms, plasma levels of the soluble receptor CD14 (sCD14), and the incidence of coronary heart disease (CHD) in a prospective cohort (the PRIME Study) of 9758 healthy men aged 50-59 years recruited in France and Northern Ireland. A nested case-control design was used, comparing the 249 participants who developed a CHD event during the 5-year follow-up with 492 population- and age-matched control subjects. The two polymorphisms were genotyped and baseline plasma concentrations of sCD14 were measured. None of the two polymorphisms, or sCD14 levels, either considered alone or in combination, were associated with the risk of CHD. The CD14/C-260T allele was associated with increased plasma concentrations of soluble thrombomodulin and vascular cell adhesion molecule-1 and, to a lesser extent, sCD14. No relationship was observed between the TLR4 polymorphism and, any of the inflammatory and endothelial markers measured. The TLR4/Asp299Gly and CD14/C-260T polymorphisms and plasma sCD14 concentrations do not appear as significant predictors of the risk of CHD in healthy individuals.

Vitamin D status in a rural population of northern Norway with high fish liver consumption.

To assess vitamin D status and the impact of three fish meals consisting of cod liver and fresh cod-liver oil on the plasma level of vitamin D metabolites in an area with high consumption of cod liver and cod-liver oil. Experimental field study. Thirty-two volunteers from the Skjervøy (70 degrees N) municipality in northern Norway were recruited to consume three traditional mølje meals, consisting of cod, cod liver, fresh cod-liver oil and hard roe, in one week. The liver and fresh cod-liver oil consumed by the participants were weighed and recorded. Blood samples were collected before the first meal, and subsequently 12 h and 4 days after the last meal. The blood samples were analysed for the vitamin D metabolites 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D). All participants answered a semi-quantitative food-frequency questionnaire, which was used to estimate usual daily nutrient intake. The study was carried out in the last part of March 2001. The median daily vitamin D intake estimated from the questionnaire was 9.9 microg. The proportion of subjects with baseline 25(OH)D level below 50 nmol l(-1) was 15.4% and none were below 37.5 nmol l(-1). Only "mølje consumption" and "time spent in daylight" were significantly associated with baseline log 25(OH)D. The mean total intake of vitamin D in the three servings was 272 microg (standard deviation 94 microg), ranging from 142 to 434 microg. Relative to baseline plasma concentration, the mean level of 25(OH)D decreased slightly in both post-consumption samples (P< or =0.03), while 1,25(OH)2D peaked 12 h after the final meal (P=0.03). Three mølje meals provided, on average, an amount of vitamin D equal to 54 times the recommended daily dose. Subjects with food consumption habits that included frequent mølje meals during the winter sustained satisfactory vitamin D levels in their blood, in spite of the long "vitamin D winter" (i.e. absence of ultraviolet-induced vitamin D production in the skin).