A doppler ultrasound study of human fetal vascular dynamics

The objectives of the study were fourfold: The first objective was to obtain a non-invasive method of measuring volume blood flow in the lower thoracic level of the human fetal descending aorta with particular emphasis on pulsatile changes in the blood flow velocity and vessel diameter. A discussion on technical and methodological aspects of volume blood flow measurements can be found in the second chapter Having studied the technical and methodological aspects of volume blood flow measurements in the descending aorta of the human fetus, and becoming more aware of the major limitations of such ultrasonic measurements, the second objective was to investigate and to collect data on normal pregnancy in the third trimester. The data from an initial study of twenty patients can be found in the third chapter. A cardiac arrhythmia alters the "milieu interieur" and the adjustments that the human fetal cardiovascular system makes are of physiological importance. By investigating volume blood flow in the human fetus in the presence of an arrhythmia, our third objective was to elucidate the compensatory mechanisms that occur in the human fetus during such adverse conditions, and the data are presented in the fourth chapter. Intrauterine growth retardation is a complication of pregnancy that is seen frequently in ante-natal clinics and on ante-natal wards. It also, unfortunately, tends to be a recurring problem for the expectant mother. The fourth objective was to investigate the changes that might occur in blood flow velocity waveforms in cases of intrauterine growth retardation and to assess the value of blood flow velocity waveform recordings for the early detection of such compromised fetuses. The data from these studies can be found in the fifth chapter

Pathology and clinical relevance of fetal blood flow measurements.

Peer Reviewe

Fetal blood flow velocity waveforms in relation to changing peripheral vascular resistance.

Contains fulltext : 86673.pdf (publisher's version ) (Open Access)In an acute experiment in Texel ewes, Doppler flow velocity waveforms from the fetal descending aorta were related to peripheral vascular resistance as calculated from perfusion pressure divided by electromagnetically measured volume flow in the descending aorta. Vascular resistance was increased by stepwise embolization of the peripheral circulation via repeated bolus administration of Sephadex G-25 microspheres. A rise in peripheral vascular resistance was associated with a reduction in peak and end-diastolic flow velocity and an increase in Pulsatility Index. Clinically, if similar changes are observed in growth retarded fetuses, the findings are usually interpreted to represent 'uteroplacental insufficiency'. Present data provide direct evidence that raised peripheral vascular resistance does indeed produce such waveform changes.1 maart 198

Blood flow in the fetal descending aorta during fetal cardiac arrhythmia.

Peer Reviewe

Synthesis and characterization of polystyrene-graphite nanocomposites via surface RAFT-mediated miniemulsion polymerization

Graphite oxide (GO) was prepared and immobilized with dodecyl isobutyric acid trithiocarbonate (DIBTC) reversible addition-fragmentation chain transfer (RAFT) agent. The hydroxyl groups of GO were attached to the DIBTC RAFT agent through an esterification process. The resultant modified GO was used for the preparation of polystyrene (PS)/graphite nanocomposites in miniemulsion polymerization. The RAFT-grafted GO (GO-DIBTC) at various loadings was dispersed in styrene monomer, and the resultant mixtures were sonicated in the presence of a surfactant (sodium dodecylbenzene sulfonate) and a hydrophobe (hexadecane) to form miniemulsions. The stable miniemulsions thus obtained were polymerized using azobisisobutyronitrile as the initiator to yield encapsulated PS-GO nanocomposites. The molar mass and polydispersity index of PS in the nanocomposites depended on the amount of RAFT-grafted GO in the system, in accordance with the features of the RAFT polymerization method. The PS-GO nanocomposites were of exfoliated morphology, as confirmed by X-ray diffraction and transmission electron microscopy measurements. The thermal stability and mechanical properties of the PS-GO nanocomposites were better than those of the neat PS polymer. Furthermore, the mechanical properties were dependent on the modified GO content (i.e., the amount of RAFT-grafted GO). © 2011 Wiley Periodicals, Inc.Articl

Assessing emotional and behavioral problems in children with intellectual disability: Revisiting the factor structure of the Developmental Behaviour Checklist

The objective of the reported study was to reassess the factor structure of the Developmental Behaviour Checklist (DBC) in a large cross-cultural sample representing all levels of intellectual disability. Parent and teacher DBC ratings on a combined sample of 1536 Dutch and Australian children and adolescents (ages 3-22) with mild to profound intellectual disability were used. Principal components analyses produced five subscales: Disruptive/Antisocial, Self-Absorbed, Communication Disturbance, Anxiety, and Social Relating, explaining 43.7% of the total variance. Internal consistencies of these subscales ranged from .66 to .91. The revised factor structure of the DBC appears to be an improved and useful tool for assessing emotional and behavioral problems in children with intellectual disabilities

Influence of the Crystalline State on Photoinduced Dynamics of Photoactive Yellow Protein Studied by Ultraviolet-Visible Transient Absorption Spectroscopy

Time-resolved ultraviolet-visible spectroscopy was used to characterize the photocycle transitions in single crystals of wild-type and the E-46Q mutant of photoactive yellow protein (PYP) with microsecond time resolution. The results were compared with the results of similar measurements on aqueous solutions of these two variants of PYP, with and without the components present in the mother liquor of crystals. The experimental data were analyzed with global and target analysis. Distinct differences in the reaction path of a PYP molecule are observed between these conditions when it progresses through its photocycle. In the crystalline state i), much faster relaxation of the late blue-shifted photocycle intermediate back to the ground state is observed; ii), this intermediate in crystalline PYP absorbs at 380 nm, rather than at 350–360 nm in solution; and iii), for various intermediates of this photocycle the forward reaction through the photocycle directly competes with a branching reaction that leads directly to the ground state. Significantly, with these altered characteristics, the spectroscopic data on PYP are fully consistent with the structural data obtained for this photoreceptor protein with time-resolved x-ray diffraction analysis, particularly for wild-type PYP

Comparative analysis of 2-year outcomes in GRIT and TRUFFLE trials.

OBJECTIVE: To explore the effect on perinatal outcome of different fetal monitoring strategies for early-onset fetal growth restriction (FGR). METHODS: This was a cohort analysis of individual participant data from two European multicenter trials of fetal monitoring methods for FGR: the Growth Restriction Intervention Study (GRIT) and the Trial of Umbilical and Fetal Flow in Europe (TRUFFLE). All women from GRIT (n = 238) and TRUFFLE (n = 503) who were randomized between 26 and 32 weeks' gestation were included. The women were grouped according to intervention and monitoring method: immediate delivery (GRIT) or delayed delivery with monitoring by conventional cardiotocography (CTG) (GRIT), computerized CTG (cCTG) only (GRIT and TRUFFLE) or cCTG and ductus venosus (DV) Doppler (TRUFFLE). The primary outcome was survival without neurodevelopmental impairment at 2 years of age. RESULTS: Gestational age at delivery and birth weight were similar in both studies. Fetal death rate was similar between the GRIT and TRUFFLE groups, but neonatal and late death were more frequent in GRIT (18% vs 6%; P < 0.01). The rate of survival without impairment at 2 years was lowest in pregnancies that underwent immediate delivery (70% (95% CI, 61-78%)) or delayed delivery with monitoring by CTG (69% (95% CI, 57-82%)), increased in those monitored using cCTG only in both GRIT (80% (95% CI, 68-91%)) and TRUFFLE (77% (95% CI, 70-84%)), and was highest in pregnancies monitored using cCTG and DV Doppler (84% (95% CI, 80-89%)) (P < 0.01 for trend). CONCLUSIONS: This analysis supports the hypothesis that the optimal method for fetal monitoring in pregnancies complicated by early-onset FGR is a combination of cCTG and DV Doppler assessment. TRIAL REGISTRATION: GRIT ISRCTN41358726 and TRUFFLE ISRCTN56204499. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology