Advanced dynamic Doppler flow of the pulmonary artery in a normal population: reference values from 18 to 41 weeks of gestation calculated by automatic Doppler waveform analysis.

OBJECTIVE: The aim of the present cross-sectional prospective study was to establish Doppler reference ranges for blood flow velocity waveforms (V max, V mean and V min) and resistance indices (PI, RI) of the fetal pulmonary arteries using the new pulsed-wave color advanced dynamic flow (ADF) Doppler technique. METHOD: Data were collected in 206 low-risk pregnancies at 18-41 weeks of gestation. The measurements were obtained in the proximal pulmonary artery near the first bifurcation in the absence of fetal body or breathing movements. RESULTS: The pulsatility index (PI) in the pulmonary artery showed mean increases of 2.43-3.59 between gestational weeks 18 and 42. A similar pattern was observed for the resistance index (RI) with increases of 0.79-0.90. Increases in systolic (V max), mean (V mean) and end diastolic (V min) blood flow velocities of 36.0-63.3, 10.8-19.9 and 5.71-7.53 cm/s, respectively, were noted during the observation interval. CONCLUSIONS: The ranges for blood flow velocities and impedance indices in the fetal pulmonary artery calculated by the authors may serve as reference values to help distinguish a normal patient population from patients carrying fetuses at high risk for neonatal lung disease in antenatal examinations.

The plant sterol brassicasterol as additional CSF biomarker in Alzheimer's disease.

OBJECTIVE: Plant sterols (sitosterol, campesterol, stigmasterol and brassicasterol) are solely dietary-derivable sterols that are structurally very similar to cholesterol. In contrast to peripheral cholesterol, plant sterols can cross the blood-brain barrier and accumulate within mammalian brain. As an impaired function of the cerebrospinal fluid (CSF)-blood barrier is linked to neurodegenerative disorders, i.e. Alzheimer's disease (AD), we investigated whether this results in altered plant sterol concentrations in CSF. METHOD: Applying gas chromatography/mass spectrometry analysis, plant sterol concentrations were measured in plasma and CSF of patients with AD (n = 67) and controls (n = 29). Age, gender, plasma-to-CSF albumin ratio, CSF Aß(42) , CSF pTau, APOE4 genotype, and serum creatinine were applied as covariates in the statistical analysis for individual plant sterols in order to compare plasma and CSF plant sterol concentrations between patients with AD and controls. RESULTS: Albumin quotient was a consistent predictor in CSF for cholesterol and methyl plant sterols campesterol and brassicasterol. Comparison of lipid parameters per diagnosis based on relevant predictors revealed significantly lower concentrations of brassicasterol (P < 0.001) in CSF of patients with AD. Binary logistic regression analysis revealed that brassicasterol improved the predictive value when added to pTau and Aß42 in a biomarker model. CONCLUSION: Brassicasterol might be a relevant additional biomarker in AD.

Nocturnal plasma melatonin levels after flunitrazepam administration in healthy subjects.

Polysomnographic sleep patterns and melatonin secretion were investigated in 5 young (age 25.6 +/- 1.1 years) and 5 middle-aged (age 49.4 +/- 5.4 years) healthy male subjects after intravenous administration of 1 mg flunitrazepam and placebo in a randomized, double-blind and cross-over setting. The area under the curve (AUC) of total nocturnal melatonin plasma concentration decreased 23.3 +/- 11.5% in young subjects (P < or = 0.05) and 39.3 +/- 5.2% in middle-aged subjects (P < or = 0.05) after flunitrazepam infusion compared with placebo infusion. Differences in nocturnal peak values of melatonin were 5.4 +/- 22.0% in young subjects (not significant) and 34.0 +/- 14.7% in middle-aged subjects (p < or = 0.05). Flunitrazepam significantly (P < or = 0.05) improved sleep latency and the number of sleep stage changes in the group of all subjects. These results show that, although the benzodiazepine flunitrazepam improves sleep, it reduces the nocturnal secretion of melatonin, and therefore alters the circadian rhythm of a hormone which is supposed to play a special role in circadian sleep-wake rhythmicity.

A composite method for the determination of the chirality of single walled carbon nanotubes.

An approach to the unambiguous determination of the conformation of individual single walled nanotubes utilizing high-resolution transmission electron microscopy and digital image processing is described. The exit plane wave of single walled nanotubes restored from a focal series of images is used in a stepwise characterization procedure utilizing both the phase of the real space restoration and its Fourier transform. A combination of these complementary characterization steps yields an accurate measurement of the chiral vector for an individual nanotube.