Mixed exhaled nitric oxideand plasma nitrites and nitrates in newborn infants

Plasma nitrite (NO2-) and nitrate (NO3-) are the stable end-products of endogenous nitric oxide (NO) metabolism. NO is present in the exhaled air of humans, but it is not clear if exhaled NO may be an indicator of the systemic endogenous NO production. The aims of the study were to determine the levels of exhaled NO and plasma NO2-/NO3- in healthy term and preterm newborns, and to assess if exhaled NO correlates with plasma NO2-/NO3- at birth. After the stabilization of the newborn, we measured by chemiluminescence the concentration of NO in the mixed expired breath of 133 healthy newborns. Measurement of exhaled NO was repeated after 24 and 48 hours. Plasma NO2-/NO3- levels at birth were measured by the Griess reaction. NO concentrations were 8.9 (CI 8.1-9.8) parts per billion (ppb), 7.7 (CI 7.2-8.3) ppb and 9.0 (CI 8.4-9.6) ppb at birth, 24 and 48 hours, respectively. At birth, exhaled NO was inversely correlated with gestational age (p=0.008) and birth weight (p<0.001). Plasma NO2-/NO3- level was 27.30 (CI 24.26-30.34) micromol/L. There was no correlation between exhaled NO and plasma NO2-/NO3- levels at birth (p=0.88). We speculate that the inverse correlation between exhaled NO and gestational age and birth weight may reflect a role of NO in the postnatal adaptation of pulmonary circulation. At birth, exhaled NO does not correlate with plasma NO2-/NO3- and does not seem to be an index of the systemic endogenous NO production

Atassia acuta in tirosinemia tipo I. Nuovo aspetto di una rara malattia

The Authors report an unusual case of tyrosinemia type I, chronic form, in which the diagnosis was made only after an episode of acute ataxia. Strict dietary treatment improved the neurologic signs. At the moment there is no evidence of hepatoma. The Authors stress the diagnostic differential elements underlying the importace of determination of succinylacetone by GC/MS analysis

Rapid determination of creatinine in serum and urine by ion-pair high-performance liquid chromatography

We report a simple and reliable high performance liquid chromatography method for measuring creatinine in serum and urine. The chromatographic run is performed on a C-18 column after protein precipitation with acetone and addition of cimetidine as an internal standard. The separation is carried out in 20 min at a flow rate of 0.8 ml/min, with a mobile phase consisting of 100 mmol/l sodium dihydrogen phosphate solution, containing 30 mmol/l sodium lauryl sulfate pH 3.0 and acetonitrile (60:36, v/v). The absorbance is monitored at 200 nm. The relationship between creatinine concentration and the creatinine/internal standard peak area is linear up to 1,088 mu mol/l. Within-run precision measured at three different creatinine concentrations ranges from 0.89% to 2.34% in serum and from 0.34% to 1.10% in urine. Between-run precision varies from 1.68% to 3.17% in serum and from 1.58% to 1.85% in urine over a wide range of concentrations. Analytical recovery is between 98.71% and 101.25% in serum and between 98.96% and 100.27% in urine. The detection limit is 3.24 mu mol/l for a signal-to-noise ratio of 3. The method shows a good linearity with the reference isotope dilution gas chromatography-mass spectrometry procedure (r=0.999), without interferences, even in the presence of high bilirubin concentrations