Biomedical subjects

Hong Gu

Publications and source records attributed to Hong Gu.

23 records · Page 2Linked to original sources

PubMed2002

Hypoplastic left heart in a female infant with partial trisomy 4q due to de novo 4;21 translocation.

We present a female infant with mild dysmorphic features and congenital heart defect: hypoplastic left heart with aortic atresia and hypoplastic aortic arch, ventricular septal defect, and a nonrestrictive atrial communication. Chromosome analysis showed an unbalanced translocation that contained additional material from 4q translocated onto 21q. This resulted in partial trisomy 4 and monosomy for the 21q telomeric region. The derivative chromosome was characterized using G-banding, M-FISH, and whole chromosome painting. The karyotype was described as 46,XX,der(21)t(4;21)(q25;q22.3).ish(wcp4+;wcp21+). Additional analyses with FISH probes specific for 21q 22.3, 21q22.2, 21q21.1, and 21q11.2 did not indicate any chromosome 21 duplication within the derivative chromosome 21. Monosomy for the telomeric portion of 21q was demonstrated using a tel 21q probe (Oncor). The patient underwent stage 1 Norwood procedure to manage her heart defect. Poor feeding and failure to thrive complicated the postsurgical period. The child subsequently underwent funduplication and feeding tube placement, and at 4.5 months of age presented with microcephaly and developmental delay. Hypoplastic left heart was previously reported with increased frequency in relatively common numeric chromosomal aberrations, such as monosomy X, trisomies 21, 18, and 13, and in various structural chromosomal defects. Our report presents new evidence for the co-occurrence of hypoplastic left heart with a duplicated portion of chromosome 4 distal to 4q25. In addition, monosomy for the telomeric region of chromosome 21 may have implications in the phenotype.

Chromosomes, Human, Pair 21↗

PubMed2002

Simultaneous perfusion and BOLD imaging using reverse spiral scanning at 3T: characterization of functional contrast and susceptibility artifacts.

Reverse spiral scanning with arterial spin-labeling was developed at 3T to simultaneously detect perfusion and BOLD signals in the brain by subtracting or adding the control and labeled images, respectively, in the same dataset. BOLD contrast was improved with the longer effective echo time achieved in the reverse spiral scan compared to conventional forward spiral scans. Susceptibility artifacts near air-tissue interfaces in the brain were substantially reduced in the reverse spiral images due to their early data acquisition time and, hence, less signal attenuation. Brain activation experiments with the reverse spiral scan were performed on normal subjects and were compared to forward spiral imaging in the same subjects. The experiments demonstrated that reverse spiral imaging was able to detect perfusion and BOLD signals simultaneously and reliably, even in the brain regions with severe susceptibility-induced local gradients, while forward spiral scans were either not optimal for detecting the two functional signals at the same time or were vulnerable to susceptibility artifacts.

Adult↗

PubMed2002

Single-shot interleaved z-shim EPI with optimized compensation for signal losses due to susceptibility-induced field inhomogeneity at 3 T.

A new single-shot echo-planar imaging (EPI) sequence with interleaved z-shim and optimized compensation for susceptibility-induced signal loss is proposed in this paper. Experiments on human brain demonstrated that the new method is able to regain signal dropout in brain areas with severe susceptibility-induced local gradients, while its image acquisition speed is comparable to that of conventional single-shot EPI techniques. Significant signal-to-noise ratio improvements were demonstrated in the ventral prefrontal and lateral temporal lobes with the new technique compared to a conventional EPI. Brain activation experiments with a bilateral finger-tapping task were performed with intentionally introduced local gradients near the left sensorimotor cortex, by a small gadolinium (Gd)-doped bottle placed on the left side of the head. The results of the functional experiments showed that the interleaved z-shim EPI sequence effectively recovered the signal loss caused by the Gd-doped bottle and reliably detected activation signals in bilateral sensorimotor regions, while the activation signals on the left side diminished considerably in a conventional EPI technique. The new technique, with the capability of reducing susceptibility artifacts and rapid scanning speed, may be particularly useful for event-related functional MRI experiments in the base of the brain, which are of great importance in neuropsychiatric studies.

Adult↗

PubMed2002

The role of endothelin in oxygen-induced contraction of the ductus arteriosus in rabbit and rat fetuses.

The role of endothelin in oxygen-induced contraction remains controversial. The present study was designed to investigate the role of endothelin in O2-induced contraction in the isolated ductal preparation of rabbit and rat, using the endothelin receptor antagonists, bosentan (antagonist for both ET-A and ET-B receptors) and BQ 485 (an ET-A selective antagonist). The ductus was isolated from fetal rabbits at 30 days of gestation (term 31 days) and fetal rats at 21 days of gestation (term 22 days). In the rabbit ductus with intact endothelium, 13% of the O2-induced contraction was inhibited by bosentan and 14% by BQ 485. In the rabbit ductus without endothelium, bosentan did not cause significant inhibition of the oxygen-induced contraction. In the rat ductus with intact endothelium, about 44% of the O2-induced contraction was inhibited by bosentan. In the rat ductus without endothelium, O2-induced contraction was 20% less than that in the ductus with intact endothelium. In the rat ductus without endothelium, bosentan further decreased the oxygen-induced contraction by about 24%. These data suggest that (1) endothelin plays a significant role in O2-induced contraction in the isolated ductus arteriosus, (2) there is a species difference in the degree of contribution of endothelin to the O2-induced ductal contraction, and (3) there is a species difference in the degree of contribution of the endothelium and vascular smooth muscle cells to the release of endothelin from the ductus arteriosus.

Animals↗

PubMed2002

Inversion profiles of adiabatic inversion pulses for flowing spins: the effects on labeling efficiency and labeling accuracy in perfusion imaging with pulsed arterial spin-labeling.

The inversion profile of adiabatic inversion pulses is essential to the accuracy of perfusion measurement with pulsed arterial spin-labeling (ASL). In this paper, the inversion profiles for flowing spins were investigated using a numerical solution of the modified Bloch equations including a term for moving spins. Inversion profiles for spins flowing at a constant or varying velocity were examined for hyperbolic secant (HS) and frequency-offset corrected inversion (FOCI) pulses. Distortions of the inversion profiles were found for both pulses with spins flowing within physiological velocity range. The effects of the distorted profiles on labeling efficiency and labeling accuracy in the application of pulsed ASL perfusion imaging were analyzed. These effects should be taken into account in ASL techniques, in order to obtain robust and accurate perfusion measurements.

Blood Flow Velocity↗