A new, rapid, sensitive and accurate gradient reversed-phase high-performance liquid chromatography technique for simultaneous separation and analysis of sildenafil citrate (SC), its N-desmethyl active metabolite - N-desmethylsildenafil (UK-103,320) in the presence of different drugs in human urine was developed. The analysed drugs were extracted from urine by liquid-liquid extraction. Effective RP-HPLC separation of the examined drugs was performed using a Merck LiChroCART® analytical column (Purospher® STAR RP-18 endcapped, 125 x 3 mm, particle size 5 μm) with a gradient mobile phase system and diode array or fluorescence detector. Linear ranges of detection for SC and UK-103,320 were found to be 0.03-8.5 μg mL-1 (r 2 = 0.9994) for both compounds. Linear ranges for other drugs (analgesic, antibiotic, diuretic and demulcent), which could exist in urine from patients treated with SC were also determined. Complete separation of all analytes was achieved below 25 min. The retention times for all studied analytes ranged from 4.76 to 18.84 min. The limits of detection and limits of quantification for both analysed compounds were calculated and recovery studies were also performed. The mean absolute recoveries of SC and UK-103,320 were > 94%. The new procedure was suitably validated and successfully applied for the analysis of SC, its active metabolite and other drugs in urine samples of patients with pulmonary hypertension.

A HPLC system for separation and determination of methylxanthines and selected drugs has been developed. Teophylline, 1-methylxanthine, 3-methylxanthine, 1,3-dimethyluric acid, caffeine, paracetamol, furosemide, dexamethasone, prednisolone, cefazolin and imipenem have been determined. A RP-18e column with a RP-18 pre-column and a DAD detector were used. Gradient elution with 0.05% TFA aqueous solution with acetononitrile at the flow rate of 0.8 mL min-1 was applied. The developed system was used to determine the examined compounds in urine samples.

Background: Intensive care units (ICUs) are hot zones for emergence and spread of antibiotic resistance because of frequent invasive procedures, antibiotic usage and transmission of bacteria. We report prospective data on antibiotic use and bacterial resistance from 14 academic and non-academic ICUs, participating in the ICU-STRAMA programme 1999-2003. Methods: The quantity of antibiotics delivered to each ICU was calculated as defined daily doses per 1000 occupied bed days (DDD1000). Specimens for culture were taken on clinical indications and only initial isolates were considered. Species-related breakpoints according to the Swedish Reference Group for Antibiotics were used. Antibiotic resistance was defined as the sum of intermediate and resistant strains. Results: Mean antibiotic use increased from 1245 DDD1000 in 1999 to 1510 DDD1000 in 2003 (P = 0.11 for trend). Of Staphylococcus aureus, 0-1.8% were methicillin resistant (MRSA). A presumptive extended spectrum beta-lactamase (ESBL) phenotype was found in <2.4% of Escherichia coli, based on cefotaxime susceptibility, except a peak in 2002 (4.6%). Cefotaxime resistance was found in 2.6-4.9% of Klebsiella spp. Rates of resistance among Enterobacter spp. to cefotaxime (20-33%) and among Pseudomonas aeruginosa to imipenem (22-33%) and ciprofloxacin (5-21%) showed no time trend. Conclusion: MRSA and cefotaxime-resistant E. coli and Klebsiella spp strains were few despite high total antibiotic consumption. This may be the result of a slow introduction of resistant strains into the ICUs, and good infection control. The cause of imipenem and ciprofloxacin resistance in P. aeruginosa could reflect the increased consumption of these agents plus spread of resistant clones. © 2007 The Authors.

In this study, we investigate the beat-to-beat respiratory fluctuations in pulse wave transit time (PTT) and its subcomponents, the cardiac pre-ejection period (PEP) and the vessel transit time (VTT) in ten healthy subjects. The three transit times were found to fluctuate in pace with respiration. When applying a simple breath detecting algorithm, 88% of the breaths seen in a respiration air-flow reference could be detected correctly in PTT. Corresponding numbers for PEP and VTT were 76 and 81%, respectively. The performance during hypo- and hypertension was investigated by invoking blood pressure changes. In these situations, the error rates in breath detection were significantly higher. PTT can be derived from signals already present in most standard monitoring set-ups. The transit time technology thus has prospects to become an interesting alternative for respiration rate monitoring. © International Federation for Medical and Biological Engineering 2006.

 Abstract 4615. European Heart J 2006.

[No abstract available]

We have developed and described a highly sensitive, accurate and precise reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of l-arginine and 12 molecules participating in its metabolic cycle in human urine samples. After pre-column derivatization with ortho-phthaldialdehyde (OPA) reagent containing 3-mercaptopropionic acid (3MPA), the fluorescent derivatives were separated by a gradient elution and detected by fluorescence measurement at 338 nm (excitation) and 455 nm (emission). l-Arginine (ARG) and its metabolites: l-glutamine (GLN), NG-hydroxy-l-arginine (NOHA), l-citrulline (CIT), NG-monomethyl-l-arginine (NMMA), l-homoarginine (HARG), asymmetric NG,NG-dimethyl-l-arginine (ADMA), symmetric NG,NG′-dimethyl-l-arginine (SDMA), l-ornithine (ORN), putrescine (PUT), agmatine (AGM), spermidine (SPERMD) and spermine (SPERM) were extracted in a cation-exchange solid-phase extraction (SPE) column and after derivatization separated in a Purospher® STAR RP-18e analytical column. The calibration curves of analysed compounds are linear within the range of concentration: 45-825, 0.2-15, 16-225, 12-285, 0.1-32, 15-235, 0.1-12, 0.1-12, 10-205, 0.02-12, 0.1-24, 0.01-10 and 0.01-8 nmol mL-1 for GLN, NOHA, CIT, ARG, NMMA, HARG, ADMA, SDMA, ORN, PUT, AGM, SPERMD and SPERM, respectively. The correlation coefficients are greater than 0.9980. Coefficients of variation are not higher than 6.0% for inter-day precision. The method has been determined or tested for limits of detection and quantification, linearity, precision, accuracy and recovery. All detection parameters of the method demonstrate that it is a reliable and efficient means of the comprehensive determination of ARG and its 12 main metabolites, making this approach suitable for routine clinical applications. The levels of analysed compounds in human urine can be successfully determined using this developed method with no matrix effect. © 2007 Elsevier B.V. All rights reserved.

Patient specific modelling of the blood flow through the human aorta is performed using computational fluid dynamics (CFD) and magnetic resonance imaging (MRI). Velocity patterns are compared between computer simulations and measurements. The workflow includes several steps: MRI measurement to obtain both geometry and velocity, an automatic levelset segmentation followed by meshing of the geometrical model and CFD setup to perform the simulations follwed by the actual simulations. The computational results agree well with the measured data.