New modes of data partitioning based on PARS peak alignment for improved multivariate biomarker/biopattern detection in 1H-NMR spectroscopic metabolic profiling of urine.

This paper addresses the possibility of mathematically partition and process urine 1H-NMR spectra to enhance the efficiency of the subsequent multivariate data analysis in the context of metabolic profiling of a toxicity study. We show that by processing the NMR data with the peak alignment using reduced set mapping (PARS) algorithm and the use of sparse representation of the data results in the information contained in the original NMR data being preserved with retained resolution but free of the problem of peak shifts. We can now describe a method for differential expression analysis of NMR spectra by using prior knowledge, i.e., the onset of dosing, a partitioning not possible to achieve using raw or bucketed data. In addition we also outline a scheme for soft removal of "biological noise" from the aligned data: exhaustive bio-noise subtraction (EBS). The result is a straightforward protocol for detection of peaks that appear as a consequence of the drug response. In other words, it is possible to elucidate peak origin, either from endogenous substances or from the administered drug/biomarkers. The partition of data originating from the normally regulating metabolome can, furthermore, be analyzed free of the superimposed biological noise. The proposed protocol results in enhanced interpretability of the processed data, i.e., a more refined metabolic trace, simplification of detection of consistent biomarkers, and a simplified search for metabolic end products of the administered drug.

Micellar electrokinetic chromatography separation and laser-induced fluorescence detection of the lipid peroxidation product 4-hydroxynonenal.

4-Hydroxnonenal (HNE) is a product of lipid peroxidation in biological systems that causes a variety of harmful biological effects. A method for identifying HNE based on derivatization with the fluorescent reagent dansylhydrazine (5-(dimethylamino)naphthalene-1-sulphonehydrazine (DNSH) followed by micellar electrokinetic chromatography separation laser-induced fluorescence detection has been developed. The derivatization reaction has also been investigated for significant experimental parameters and rat brain homogenates with induced lipid peroxidation have been analysed for HNE contents. The limit of detection (3 S/N) was 30 nM or 0.3 fmol in the injected sample.

Reduction of ACE activity is insufficient to decrease microalbuminuria in normotensive patients with type 1 diabetes.

OBJECTIVE: To study whether administration of 1.25 and 5.0 mg ramipril daily, compared with placebo treatment, reduces the urinary albumin excretion rate (UAER) in normotensive patients with type 1 diabetes. RESEARCH DESIGN AND METHODS: Ramipril was administered double blind at two different doses (1.25 [n = 19] and 5.0 mg [n = 18]), and compared with placebo (n = 18) after a single-blind placebo period of 1-4 weeks. The patients (total, n = 55; women, n = 14) were followed for 2 years. To document an effect on the renin-angiotensin system, ACE activity and plasma-renin activity (PRA) were measured. In addition, 24-h ambulatory blood pressure (BP) was recorded at baseline and repeated after 1 and 2 years using a Spacelab 90207 ambulatory BP recording device (Spacelab, Redmont, CA). RESULTS: Both doses of ramipril were sufficient to reduce ACE activity and to increase PRA significantly as compared with placebo (P < 0.05 for both). On the other hand, neither ambulatory nor clinic BP was affected by either dose of ramipril compared with the placebo group. There was no progression of UAER in the placebo group during the 2 years of the study. Analysis of covariance showed no differences in UAER between the three treatment groups at year 1 (P = 0.94) or year 2 (P = 0.97), after adjusting for baseline. Furthermore, there were no statistically significant changes from baseline UAER within any of the three treatment groups. CONCLUSIONS: Treatment with ramipril did not affect microalbuminuria or clinic or ambulatory BP in this study. On the basis of the present study, we question the clinical use of ACE inhibitors in stably normotensive patients with type 1 diabetes and microalbuminuria in whom a concomitant reduction in BP is not demonstrated.

On-line flow sample stacking in a flow injection analysis-capillary electrophoresis system: 2000-fold enhancement of detection sensitivity for priority phenol pollutants.

A flow injection analysis-capillary electrophoresis system has been used for on-line flow stacking of 11 US Environmental Protection Agency priority phenol pollutants. Samples containing low concentrations of phenols dissolved in deionised water are continuously delivered to the capillary opening by means of a peristaltic pump. The sample components stack at the boundary between the highly conductive separation electrolyte and the introduced sample. By selecting an appropriate electrolyte and stacking conditions the movement of the electrolyte solution inside the capillary can be reduced, thereby improving the stacking efficiency. The electrolyte used here contained 20 mM phosphate, 8% 2-butanol, and 0.001% hexamethonium bromide at pH 11.95, and the stacking was carried out at 2 kV for 240 s. These conditions allowed up to 2000-fold preconcentration of the selected phenols. No matrix removal was necessary.

Methyl malondialdehyde as an internal standard for the determination of malondialdehyde.

Methyl malondialdehyde (Me-MDA) is suggested as an internal standard for the determination of the lipid peroxidation product, malondialdehyde (MDA). A procedure for synthesising the Me-MDA sodium salt is described in detail. The purity and identity of the synthesised Me-MDA have been confirmed using nuclear magnetic resonance and UV spectroscopy, and by micellar electrokinetic chromatography. The applicability of Me-MDA as an internal standard has been demonstrated for rat brain homogenate samples. These samples were purified solely through ultrafiltration. The preferred analytical technique was capillary zone electrophoresis (CZE) with UV detection at 267 nm. The limits of detection (3 S/N) for the CZE separations of Me-MDA and MDA were 0.5 and 0.2 microM, respectively, and the total analysis time was approximately 10 min. Details of separations are also presented using high-performance liquid chromatography (HPLC) with UV detection at 245 nm, and gas chromatography, together with either electron capture or mass spectrometric detection. The GC separations require derivatisation of MDA and Me-MDA with pentafluorophenylhydrazine while the CZE and HPLC separations can be performed on the native molecules.

Optimisation of resolution in micellar electrokinetic chromatography by multivariate evaluation of electrolytes.

A novel approach to multivariate evaluation of separation electrolytes for micellar electrokinetic chromatography is presented. An initial screening of the experimental parameters is performed using a Plackett-Burman design. Significant parameters are further evaluated using full factorial designs. The total resolution of the separation is calculated and used as response. The proposed scheme has been applied to the optimisation of the separation of phenols and the chiral separation of (+)-1-(9-anthryl)-2-propyl chloroformate-derivatized amino acids. A total of eight experimental parameters were evaluated and optimal conditions found in less than 48 experiments.

Spectrofluorimetric determination of chlorophylls and pheopigments using parallel factor analysis.

In this study, parallel factor analysis (PARAFAC) was applied to fluorescence excitation emission matrices (EEM) of chlorophylls and pheopigments dissolved in acetone:water (9:1). The excitation wavelength range was from 350 to 500 nm and the emission was recorded from 600 to 730 nm. Nine standards, comprising mixtures of six analytes, were decomposed into a six-component PARAFAC model. Each component resembled the corresponding EEM of the pure analyte, demonstrating the uniqueness properties of PARAFAC. The score matrix obtained from the model was used for calibration and prediction of an independent set of standards and for eleven samples collected in the Baltic proper. The results obtained by the proposed method were compared to classical least squares (CLS) and to predictions by reference methods (HPLC and visible spectroscopy). For the independent set of standards the proposed method and CLS performed equal well in terms of predictive ability. But for the samples the proposed method yielded results that were in good agreement to the reference methods, whereas CLS failed. Also the so-called "second-order advantage" was examined, showing that not all constituents must be included in the calibration set. The concentration range was for chlorophyll a varied between 10 and 75 mug l(-1), and similar for the other analytes.

Hyphenation of gas-diffusion separation and ion chromatography. Part 1: determination of free sulfite in wines.

The hyphenation of gas-diffusion separation and ion chromatography (IC) is described as a convenient, reliable, robust, and economic method for in-line sample pre-treatment. The high selectivity associated with this method permits direct analysis of samples containing microparticulates, colloidal matter, and/or high molecular weight compounds. The determination of sulfite serves as a first example of its application. The method is based on the diffusional separation of SO2 following in-line oxidation with hydrogen peroxide to sulfate and final determination of the sulfate formed using IC. The influence of operational parameters has been thoroughly investigated and gas-diffusion cells of different geometries compared with respect to the gas-transfer rates obtained. Application to the analysis of wines demonstrates the utility of the method.

Randomised trial of effects of calcium antagonists compared with diuretics and beta-blockers on cardiovascular morbidity and mortality in hypertension: the Nordic Diltiazem (NORDIL) study.

BACKGROUND: Calcium antagonists are a first-line treatment for hypertension. The effectiveness of diltiazem, a non-dihydropyridine calcium antagonist, in reducing cardiovascular morbidity or mortality is unclear. We compared the effects of diltiazem with that of diuretics, beta-blockers, or both on cardiovascular morbidity and mortality in hypertensive patients. METHODS: In a prospective, randomised, open, blinded endpoint study, we enrolled 10,881 patients, aged 50-74 years, at health centres in Norway and Sweden, who had diastolic blood pressure of 100 mm Hg or more. We randomly assigned patients diltiazem, or diuretics, beta-blockers, or both. The combined primary endpoint was fatal and non-fatal stroke, myocardial infarction, and other cardiovascular death. Analysis was done by intention to treat. FINDINGS: Systolic and diastolic blood pressure were lowered effectively in the diltiazem and diuretic and beta-blocker groups (reduction 20.3/18.7 vs 23.3/18.7 mm Hg; difference in systolic reduction p<0.001). A primary endpoint occurred in 403 patients in the diltiazem group and in 400 in the diuretic and beta-blocker group (16.6 vs 16.2 events per 1000 patient-years; relative risk 1.00 [95% CI 0.87-1.15], p=0.97). Fatal and non-fatal stroke occurred in 159 patients in the diltiazem group and in 196 in the diuretic and beta-blocker group (6.4 vs 7.9 events per 1000 patient-years; 0.80 [0.65-0.99], p=0.04) and fatal and non-fatal myocardial infarction in 183 and 157 patients (7.4 vs 6.3 events per 1000 patient-years; 1.16 [0.94-1.44], p=0.17). INTERPRETATION: Diltiazem was as effective as treatment based on diuretics, beta-blockers, or both in preventing the combined primary endpoint of all stroke, myocardial infarction, and other cardiovascular death.

Efficacy and safety of a new long-acting drug combination, trandolapril/verapamil as compared to monotherapy in primary hypertension. Swedish TARKA trialists.

OBJECTIVE: To evaluate the clinical efficacy and safety of a new antihypertensive drug combination of trandolapril/verapamil compared to monotherapy with verapamil or trandolapril, in patients with mild to moderate primary hypertension. DESIGN: A multicentre, prospective, randomized, double-blind, controlled cross-over study with specific statistical considerations. SETTINGS: Eighteen primary health care centres and out-patient hospital clinics in Sweden. PATIENTS: Two hundred and twenty-six outpatients with uncomplicated primary hypertension with a baseline sitting diastolic blood pressure (BP) between 95 and 115 mmHg. INTERVENTIONS: After a 4-week placebo period, patients were randomized to treatment for 8 weeks with trandolapril/verapamil (2 mg/180 mg) or each drug alone (verapamil 240 mg, trandolapril 2 mg) for 8 weeks. MAIN OUTCOME MEASURES: Treatment responses (blood pressure (BP) fall and rate pressure product) to the three regimens with statistical comparison and also in relation to plasma concentrations of active renin (AR). Adverse events and safety were also evaluated. RESULTS: The mean BP fall was significantly greater with the combination (20/15 mmHg), p < 0.00054, as compared to both trandolapril (14/11 mmHg) or verapamil (13/11) mmHg. The difference between verapamil and trandolapril was not significant. Rate pressure product decreased significantly more on the combination, p < 0.001, than on trandolapril or verapamil alone. Treatment response to trandolapril was positively correlated to initial AR (r = 0.30-0.43). All treatments were well tolerated and safe. CONCLUSIONS: The new fixed drug combination trandolapril/verapamil was superior to monotherapy with either of these drugs alone regarding reduction of both BP and rate pressure product. This combination can be safely and effectively used for the treatment of mild to moderate primary hypertension.

Free malondialdehyde determination in rat brain tissue by capillary zone electrophoresis: evaluation of two protein removal procedures.

Two procedures for the determination of underivatised, free malondialdehyde in rat brain tissue have been evaluated. Both procedures are based on capillary zone electrophoresis (CZE) and UV detection at 267 nm and differ only with respect to the protein removal step, for which ultrafiltration or precipitation with acetonitrile have been employed. The total analytical processes include sample homogenisation, addition of antioxidant, protein removal, and separation and detection in the CZE system, and take less than 20 min. The CZE buffer consists of 10 mM borax and 0.5 mM CTAB at pH 9.3. The malondialdehyde peak reaches the detector about 3 min after injection as one of the very first peaks in the electropherogram. The limit of detection (3 S/N) is 0.2 microM, corresponding to 4 fmol for an injection volume of 20 nl. The method is fast, reproducible and has a large linear range, spanning 0-200 microM.

The renin-angiotensin-aldosterone system is suppressed in adults with Type 1 diabetes.

Poor glycaemic control and high blood pressure are two important risk factors for the development of retinopathy and nephropathy in Type 1 diabetes. The renin-angiotensin-aldosterone system (RAAS) may be involved in this process, since treatment with angiotensin-converting enzyme (ACE) inhibitors postpones the development of these complications. We investigated whether plasma renin activity (PRA), plasma angiotensin II (Ang II) and atrial natriuretic peptide (ANP) differed in Type 1 diabetic patients compared with healthy controls. We recruited 80 patients with Type 1 diabetes of more than 10 years' duration and 75 age-matched controls. We found that PRA and Ang II concentrations were significantly lower in patients than in the controls. The levels of ANP, on the other hand, were higher in patients than in controls. PRA correlated negatively to the mean value of HbA(1c) during the previous five years. PRA and Ang II were significantly lower in patients with mean HbA(1c) >8.4% compared with those with mean HbA(1c) <7.2%. In summary, we found patients with Type 1 diabetes to have RAAS suppression and increased ANP levels, suggesting a state of fluid retention.

Direct determination of small cations in proteinaceous samples using a flow injection-capillary electrophoresis system.

A method is described for the direct determination of small inorganic cations in samples containing large amounts of proteins, such as milk or blood plasma. The method is based on electrokinetic injection in a flow injection analysis-capillary electrophoresis (CE) system. The selected CE-electrolyte, containing 5 mM 4-aminopyridine and 7 microM cetyltrimethylammonium bromide at pH 4.5, prevents detrimental protein adsorption on the capillary walls. Therefore, no sample pretreatment, except for dilution, is required. Up to 30 repeated injections in one electrophoretic run can be performed, yielding RSD values of the migration time of less than 1 and 2.5% (n=30) for milk and blood plasma samples, respectively.

The circulating renin-angiotensin system during treatment with metoprolol or captopril in patients with heart failure due to non-ischaemic dilated cardiomyopathy.

OBJECTIVE: To investigate the effects of beta-blocker (metoprolol) or angiotensin-converting enzyme inhibitor (captopril) treatment on neurohormonal function in a randomized prospective study on patients with heart failure due to dilated cardiomyopathy. PATIENTS: Fifty-four patients (42 men and 12 women, mean age 50 years) were studied. There were three patients in NYHA (New York Heart Association) functional class I, 32 patients in class II and 19 patients in class III. METHODS: Measurements of plasma renin activity (PRA). plasma angiotensin II (A II) concentration and plasma atrial natriuretic peptide (ANP) concentration were made at rest and also in a subgroup (n = 32) during exercise. The urinary excretion of aldosterone was also determined. Investigations were performed at baseline, and after 3 and 6 months. Therapy was then stopped and the patients were re-investigated 1 month thereafter. RESULTS: The mean level of PRA was normal at baseline, reduced during therapy with metoprolol, and increased during therapy with captopril. The mean plasma concentration of A II was reduced during exercise and there was a trend towards a reduction even at rest in the metoprolol group, but not in the captopril group. The urinary excretion of aldosterone decreased in both groups. The mean plasma concentration of ANP was elevated at baseline and declined during exercise in the metoprolol group. CONCLUSION: In patients with dilated cardiomyopathy and only a partly activated renin-angiotensin system, both metoprolol and captopril reduced urinary excretion of aldosterone. Furthermore, metoprolol suppressed the exercise-induced increase in ANP, suggesting a favourable effect on ventricular performance.

Efficacy and safety of telmisartan, a selective AT1 receptor antagonist, compared with enalapril in elderly patients with primary hypertension. TEES Study Group.

OBJECTIVE: To assess the antihypertensive efficacy and safety of the novel AT1 receptor antagonist, telmisartan, compared with that of enalapril in elderly patients with mild to moderate hypertension. DESIGN: A 26-week, multicenter, double-blind, parallel-group, dosage titration study. METHODS: A total of 278 patients aged > or = 65 years were randomized to eithertelmisartan or enalapril once a day. The telmisartan dosage was increased from 20 to 40-80 mg and that of enalapril from 5 to 10-20 mg at 4-week intervals until trough supine diastolic blood pressure was < 90 mmHg. After 12 weeks, hydrochlorothiazide at 12.5-25 mg once a day was added to the treatment regimen of those patients not controlled on monotherapy. RESULTS: Both treatments lowered blood pressure in a comparable and clinically meaningful manner. The adjusted mean changes from baseline in supine diastolic blood pressure at trough were -12.8 mmHg for telmisartan and -11.4 mmHg for enalapril (P = 0.074). Mean changes in supine systolic blood pressure were -22.1 mmHg for telmisartan and -20.1 mmHg for enalapril (P = 0.350). Overall, 63 and 62% of patients responded to telmisartan and enalapril, respectively, with a supine diastolic blood pressure of < 90 mmHg. Both regimens provided effective blood pressure lowering over the 24 h dosing interval, as determined by ambulatory blood pressure monitoring. Both regimens were well tolerated; however, patients on the enalapril regimen had more than double the incidence of treatment-related cough compared with those on the telmisartan regimen (16 versus 6.5%). CONCLUSIONS: These results demonstrate that telmisartan is well tolerated and is at least as effective as enalapril in treating elderly patients with mild to moderate hypertension.

Effect of angiotensin-converting-enzyme inhibition compared with conventional therapy on cardiovascular morbidity and mortality in hypertension: the Captopril Prevention Project (CAPPP) randomised trial.

BACKGROUND: Angiotensin-converting-enzyme (ACE) inhibitors have been used for more than a decade to treat high blood pressure, despite the lack of data from randomised intervention trials to show that such treatment affects cardiovascular morbidity and mortality. The Captopril Prevention Project (CAPPP) is a randomised intervention trial to compare the effects of ACE inhibition and conventional therapy on cardiovascular morbidity and mortality in patients with hypertension. METHODS: CAPPP was a prospective, randomised, open trial with blinded endpoint evaluation. 10,985 patients were enrolled at 536 health centres in Sweden and Finland. Patients aged 25-66 years with a measured diastolic blood pressure of 100 mm Hg or more on two occasions were randomly assigned captopril or conventional antihypertensive treatment (diuretics, beta-blockers). Analysis was by intention-to-treat. The primary endpoint was a composite of fatal and non-fatal myocardial infarction, stroke, and other cardiovascular deaths. FINDINGS: Of 5492 patients assigned captopril and 5493 assigned conventional therapy, 14 and 13, respectively, were lost to follow-up. Primary endpoint events occurred in 363 patients in the captopril group (11.1 per 1000 patient-years) and 335 in the conventional-treatment group (10.2 per 1000 patient-years; relative risk 1.05 [95% CI 0.90-1.22], p=0-52). Cardiovascular mortality was lower with captopril than with conventional treatment (76 vs 95 events; relative risk 0.77 [0.57-1-04], p=0.092), the rate of fatal and non-fatal myocardial infarction was similar (162 vs 161), but fatal and non-fatal stroke was more common with captopril (189 vs 148; 1.25 [1-01-1-55]. p=0.044). INTERPRETATION: Captopril and conventional treatment did not differ in efficacy in preventing cardiovascular morbidity and mortality. The difference in stroke risk is probably due to the lower levels of blood pressure obtained initially in previously treated patients randomised to conventional therapy.

Unchanged incidence of severe retinopathy in a population of Type 1 diabetic patients with marked reduction of nephropathy.

The incidence of nephropathy in Type 1 diabetes mellitus has declined during the past decade, probably as a result of improved glycaemic control. We wanted to investigate whether the incidence of severe retinopathy has changed during the same time period and to evaluate the importance of glycaemic control in relation to the development of severe retinopathy and nephropathy. All 213 patients in whom Type 1 diabetes mellitus was diagnosed before the age of 15 years between 1961 and 1980 in a district in southeastern Sweden were studied. Ninety-two per cent of the patients were followed from the onset of diabetes to 1991 or to death. The cumulative incidence of severe retinopathy was not significantly different between the patients with diabetes onset 1961-65, 1966-70, 1971-75, and 1976-80. The risk of developing severe retinopathy or nephropathy was higher in patients with very poor glycaemic control (HbA1c > or = 8.4%) vs patients with poor control (HbA1c > or = 7.2 < 8.4%; p < 0.001). Patients with poor control had an increased risk of developing severe retinopathy vs patients with good control (HbA1c < 7.2%; p < 0.008) but there was no difference in the risk of nephropathy. No patients with good control developed nephropathy and only one patient developed severe retinopathy during 25 years of diabetes.

Whole-body cooling increases plasma endothelin-1 levels in women with primary Raynaud's phenomenon.

To understand better the role of endothelin-1 (ET-1) in the pathogenesis of primary Raynaud's phenomenon (PRP), we investigated the basal ET-1 plasma levels and changes after whole-body cooling in healthy women and those with PRP. The study was performed as an open parallel-group comparison during the month of February. The Raynaud group included 21 female patients (mean age 45.3 years, range 21-57 years) who had had disabling Raynaud's phenomenon for a mean period of 17 years (range 2-26 years). The control group consisted of 25 healthy women (mean age 43.6 years, range 27-56 years). Plasma levels of ET-1 were measured on two separate occasions: once after 30 min of rest at room temperature and after 40 min of whole-body cooling. There were no significant differences in baseline plasma ET-1 levels between the two groups of women. The plasma ET-1 levels increased significantly in the PRP group after cold exposure (mean difference 0.11 pmol l-1, 95% CI 0.005-0.214, P = 0.012). In contrast, the levels of plasma ET-1 in the control group did not change significantly after cold provocation. In conclusion, no differences in plasma basal levels of ET-1 were observed between the two groups. However, women suffering from Raynaud's phenomenon responded with a slight but significant elevation in plasma levels of ET-1 after whole-body cooling, whereas the healthy control subjects did not. The results from the present study confirm previous observations that endothelial dysfunction may be of aetiological importance in PRP.

Determination of malondialdehyde in rat brain by capillary zone electrophoresis.

A method for determination of malondialdehyde with capillary electrophoresis using UV detection at 267 nm has been developed. The buffer system consisted of 10 mM borax and 0.5 mM CTAB at pH 9.3. Malondialdehyde migrated as the first peak in the electropherogram at 2.6 min. Limit of detection was 1.2 microM corresponding to 7.8 pg. Malondialdehyde was determined before and after stimulating lipid peroxidation with the addition of ferrous ammonium sulphate to homogenates of rat brain tissue. Proteins were precipitated by boiling and removed from the brain homogenates with centrifugation. No further pretreatment was made before injecting the homogenates on the CE system. Non-precipitated homogenates could also be analyzed, but this required washing of the capillary with 0.1 M NaOH before introduction of the next sample.