Evaluation of clinical and home performance of the 13C-urea breath test for the detection of Helicobacter pylori

OBJECTIVE: This study analyses the 13C-urea breath test with the aim of determining the optimal time interval between dosing and breath sampling and examines the feasibility of having patients perform the test without supervision at home. DESIGN: Prospective study comparing the 13C-urea breath test with four antral biopsy-based tests in a random population undergoing upper gastrointestinal endoscopy. SETTING: One university hospital and one general hospital. PATIENTS: One hundred and four patients were included; 61 were Helicobacter pylori-positive and 43 H. pylori-negative according to biopsy-based tests. INTERVENTIONS: The 13C-urea breath test was performed at home by collecting a baseline and two post-dosing samples; the next day it was performed clinically by collecting a baseline and six post-dosing samples. A 100 mg dose of 13C-urea and a test meal were used. OUTCOME MEASURES: The breath samples collected were analysed. Excess delta 13CO2/12CO2 values above five per million were considered positive. RESULTS: The specificity of the clinical test was 100% whereas that of the home-based test was 95.1%. The sensitivity of the clinical test depended on the time interval between dosing and collection of the evaluated sample. Sensitivity was 100% if the sample was taken 50 min or more after dosing. The home-based test had a sensitivity of 94.8%. CONCLUSION: To obtain maximum sensitivity (100%) using the single-sample technique the sample has to be collected at least 50 min after dosing. It is feasible to have the test performed at home. Patient selection and thorough instruction are necessary.     

Stereodifferentiation--the effect of P chirality of oligo(nucleoside phosphorothioates) on the activity of bacterial RNase H

P stereoregular phosphorothioate analogs of pentadecamer 5'-d(AGATGTTTGAGCTCT)-3' were synthesized by the oxathiaphospholane method. Their diastereomeric purity was assigned by means of enzymatic degradation with nuclease P1 and, independently, with snake venom phosphodiesterase. DNA-RNA hybrids formed by phosphorothioate oligonucleotides (PS-oligos) with the corresponding complementary pentadecaribonucleotide were treated with bacterial RNase H. The DNA-RNA complex containing the PS-oligo of [all-RP] configuration was found to be more susceptible to RNase H-dependent degradation of the pentadecaribonucleotide compared with hybrids containing either the [all-SP] counterpart or the so called 'random mixture of diastereomers' of the pentadeca(nucleoside phosphorothioate). This stereodependence of RNase H action was also observed for a polyribonucleotide (475 nt) hybridized with these phosphorothioate oligonucleotides. The results of melting studies of PS-oligo-RNA hybrids allowed a rationalization of the observed stereodifferentiation in terms of the higher stability of heterodimers formed between oligoribonucleotides and [all-RP]-oligo(nucleoside phosphorothioates), compared with the less stable heterodimers formed with [all-SP]-oligo(nucleoside phosphorothioates) or the random mixture of diastereomers.     

Systolic function of the univentricular heart: comparison of the Simpson's rule with acoustic quantification

BACKGROUND: Acoustic quantification (AQ) is a new method of obtaining real-time information about systolic ventricular function. This method establishes a ;blood-tissue interface' and computes an intraventricular blood volume in real time to derive a beat to beat instantaneous ejection fraction. AQ assessment of systolic function has been reported previously in patients with normal cardiotypes and varying degrees of myocardial dysfunction. OBJECTIVE: To determine the potential utility of AQ in patients with abnormal ventricular morphology, in whom systolic function may be difficult to measure by traditional methods. PATIENTS AND DESIGN: Seventeen children (nine females) ranging in age from five days to 18 years (mean 6.9 years) with univentricular left ventricle heart morphology underwent a prospective and comparative echocardiographic study of ventricular function with the use of AQ and manual planimetry (single plane Simpson's rule). Imaging was done during steady state without sedation. Routine scan planes were performed, followed by repeat scanning of the univentricle from the apical four-chamber view in the AQ mode. Subsequently, manual planimetry using Simpson's rule was performed from an online graphical analysis package to measure systolic and diastolic frames from the conventional replay images. These data were used to calculate ejection fraction using standards previously established. The results were then compared with real-time AQ results. SETTING: Tertiary care referral center. RESULTS: Scan time for the combined standard and AQ imaging averaged 45 mins (range 35 to 65 mins). Measured ejection fraction by AQ and manual planimetry were 44 +/- 11% and 46 +/- 10%, respectively. Statistical analysis by repeated measures ANOVA with Bonferroni/Dunn correction (F = 0.6, df = 1,32, P = 0.44) demonstrated significant agreement between AQ and manual planimetry with an intraclass correlation coefficient of 0.93. Bland-Altman analysis was used to provide a graphic display of the clinical significance of differences in the comparison of the two methods of measurement. CONCLUSIONS: These findings support the use of AQ for continuous online determination of indexes of systolic function for patients with univentricular left ventricle morphology. The variability in the morphology inherently present within this group of patients results in a wider variability of determined ejection fraction. Particular attention must be directed to the technical aspects of image acquisition and AQ application to ensure accuracy.     

Angiotensinogen and angiotensin-I converting enzyme gene polymorphisms and the risk of coronary artery disease in Chinese

We investigated extracts of timothy grass pollen from four seasons (1989, 1990, 1991, and 1994) by protein content, SDS-PAGE, immunoblot, RAST, RAST inhibition, and crossed immunoelectrophoresis. Extract of the pollen from 1991 showed the lowest yield in quantitative assays. SDS-PAGE, crossed immunoelectrophoresis, RAST, and RAST inhibition expressed approximately comparable patterns for all extracts except that from 1991. Obviously, the quality of grass pollens, as shown for some ragweed (Ambrosia elatior) pollens depend on year of collection. Our findings are partially in agreement with some earlier examinations of the quality of timothy pollen from different pollen seasons.