Nutritional Aspects of Breath Testing Based on Stable Isotopes

Stable isotope methodologies offer a number of possibilities for the nutritional assessment of many different processes and metabolic pathways. The application of stable isotopes has been boosted by the development of new mass spectrometers, lower costs of probes, and the risks associated with radioactive tracers. The use of ¹³C as a tracer offers all the advantages of stable isotopes and has been widely applied for measuring various types of metabolic processes. This review is focused on clinical and nutritional assessments using ¹³C breath tests.     

N3-arylspiroimidazolidine-2,4-diones N3-arylspiroimidazolidine-2-thio-4-ones and 4-hydroxy derivatives. Synthesis and anthelmintic activity

The synthesis of new N3-arylciclohexanespiroimidazolidine-2,4-diones, N3-arylciclohexanespiroimidazolidine-2-tio-4-ones and the 4-hydroxy derivatives is described and their structures discussed on the basis of I.R. and 1H-N.R.M. data. The anthelmintic activity of these compounds was tested.     

Absence of relaxation to lactate in human placental vessels of pregnancies with severe preeclampsia

OBJECTIVE: Our objective was to determine whether the observed relaxation to lactate and other agents in placental vessels of normal pregnancies is altered in severe preeclampsia.STUDY DESIGN: Isolated placental arteries and veins from women with severe preeclampsia and uncomplicated term pregnancies were precontracted with prostaglandin F_2α under 5% oxygen and 5% carbon dioxide with the balance nitrogen (Po₂ 35 to 38 torr) and then exposed to lactate (1 to 10 mmol/L, pH 7.4, n = 8 to 15), arachidonic acid (0.01 to 10 μmol/L, n = 6 to 13), nitroglycerin (1 nmol to 1 μmol/L, n = 4 to 12), or forskolin (0.01 to 10 μmol/L, n = 6 to 9). The response to lactate was also examined in placental vessels from appropriate-for-gestational-age preterm deliveries (n = 8) for comparison with a similar group with severe preeclampsia (n = 8). The t test and analysis of variance statistics were used.RESULTS: Relaxation to lactate was markedly inhibited in both placental arteries and veins of women with severe preeclampsia compared with vessels from uncomplicated term or preterm pregnancies. Responses to the other relaxing agents were not altered in the severely preeclampsia vessels.CONCLUSIONS: In severe preeclampsia absence of lactate-induced dilatation of placental vessels may contribute to the fetal complications associated with impaired blood flow and vasospasm.     

FIA—fluorimetric determination of thiamine

A flow injection-fluorimetric determination of thiamine is reported. The procedure is based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anionic exchange resin; the fluorescence is monitored in aqueous basic solution. Concentrations of the vitamin of 0.1–4 ppm have been determined; the relative standard deviation was 1.8%. The injection rate was 28 samples/h. The influence of other substances and the determination of the drug in a pharmaceutical formulation are also reported.     

Renal and hemodialysis clearances of endogenous natriuretic peptide. A clinical and experimental study

The purpose of the present study was to assess the plasma levels of atrial natriuretic peptide (ANP) in chronically uremic patients not submitted to dialysis and to determine the predialysis plasma concentration of ANP, the effect of ultrafiltration on plasma levels of ANP (hemodialysis, (HD), and the HD clearance of ANP in a population of adult patients treated with maintenance HD. The mean plasma ANP concentration (pg/ml) in HD was 370.2 +/- 35.5 pg/ml (mean +/- SEM) before HD and decreased to 165.3 +/- 15.2 after HD (p less than 0.01). Both values were significantly higher than in controls (28 +/- 2; n = 39). The changes in plasma ANP levels correlated inversely with those in plasma protein concentration (r = -0.53; p less than 0.03; y = 48.6 +/- 0.8 x). ANP clearance across the cuprophan membrane averaged 13 +/- 6.4 ml/mn. Resting plasma ANP values in the 16 uremic patients ranged between 16 and 277 pg/ml (124 +/- 11 pg/ml). These levels were significantly higher than those observed in controls (p less than 0.01). In these patients there was a highly significant correlation between serum creatinine and plasma ANP concentrations (p less than 0.01; r = 0.75; y = 0.2x + 3). Furthermore we report the results of the determination of the renal clearance of ANP in normal dogs. In all dogs a fall in plasma ANP concentration was recorded between the aorta (28.6 +/- 4.5 pg/ml) and the renal vein (14.2 +/- 2.7 pg/ml). The renal extraction ratio averaged 51.3 +/- 3.7%. Mean ANP renal clearance was 38.2 +/- 5.2 ml/mn.(ABSTRACT TRUNCATED AT 250 WORDS)