Biomedical subjects

Lei Zhuang

Publications and source records attributed to Lei Zhuang.

12 recordsLinked to original sources

PubMed2006

Color and power Doppler sonography of extracranial and intracranial arteries in Moyamoya disease.

PURPOSE: To study the hemodynamic characteristics of moyamoya disease with color Doppler (CD) and power Doppler (PD) sonography. METHODS: The hemodynamic parameters of intracranial and extracranial arteries from 17 patients with moyamoya disease confirmed via digital subtraction angiography and 30 healthy controls were studied with conventional and transcranial CD and PD. RESULTS: The moyamoya vessels were detected as scattered color Doppler signal with low velocity and a low resistance index (RI) at the base of the brain in 10 of the 17 patients. The RI of the common carotid arteries and the internal carotid arteries of the patients was significantly higher, whereas the peak velocity was lower than in controls. The posterior carotid arteries were more frequently involved in children (43.8%) than in adults (5.6%). CONCLUSIONS: Transcranial CD and PD can be used to demonstrate the stenosis and occlusion of intracranial arteries and the abnormal vascular network at the base of the brain in most cases. Combined with the hemodynamic characteristics of extracranial arteries and the symptoms of the patients, an accurate diagnosis of moyamoya disease could be made in the majority of cases using PD.

Adolescent↗

PubMed2006

Real-time three-dimensional color Doppler flow imaging: an improved technique for quantitative analysis of aortic regurgitation.

The recently introduced real-time three-dimensional color Doppler flow imaging (RT-3D CDFI) technique provides a quick and accurate calculation of regurgitant jet volume (RJV) and fraction. In order to evaluate RT-3D CDFI in the noninvasive assessment of aortic RJV and regurgitant jet fraction (RJF) in patients with isolated aortic regurgitation, real-time three-dimensional echocardiographic studies were performed on 23 patients with isolated aortic regurgitation to obtain LV end-diastolic volumes (LVEDV), end-systolic volumes (LVESV) and RJV, and then RJF could be calculated. The regurgitant volume (RV) and regurgitant fraction (RF) calculated by two-dimensional pulsed Doppler (2D-PD) method served as reference values. The results showed that aortic RJV measured by the RT-3D CDFI method showed a good correlation with the 2D-PD measurements (r = 0.93, Y = 0.89X + 3.9, SEE = 8.6 mL, P < 0.001); the mean (SD) difference between the two methods was--1.5 (9.8) mL. % RJF estimated by the RT-3D CDFI method was also correlated well with the values obtained by the 2D-PD method (r = 0.88, Y = 0.71X + 14.8, SEE = 6.4%, P < 0.001); the mean (SD) difference between the two methods was--1.2 (7.9) %. It was suggested that the newly developed RT-3D CDFI technique was feasible in the majority of patients. In patients with eccentric aortic regurgitation, this new modality provides additional information to that obtained from the two-dimensional examination, which overcomes the inherent limitations of two-dimensional echocardiography by depicting the full extent of the jet trajectory. In addition, the RT-3D CDFI method is quick and accurate in calculating RJV and RJF.

Adolescent↗

PubMed2006

Quantitative assessment of myocardial perfusion defects with real-time three-dimensional myocardial contrast echocardiography.

OBJECTIVE: To evaluate the feasibility and accuracy of measurement of myocardial perfusion defects with intravenous contrast-enhanced real-time three-dimensional echocardiography (CE-RT3DE). METHODS: RT3DE was performed in 21 open-chest mongrel dogs undergoing acute ligation of the left anterior descending artery (LAD, n = 14) or distal branch of the left circumflex artery (LCX, n = 7). A perfluorocarbon microbubble contrast agent was injected intravenously to assess the resulting myocardial perfusion defects with Philips Sonos-7500 ultrasound system. Evans blue dye was injected into the occluded coronary artery for subsequent anatomic identification of underperfused myocardium. In vitro anatomic measurement of myocardial mass after removal of the animal's heart was regarded as the control. Blinded off-line calculation of left ventricular mass and perfusion defect mass from RT3DE images were performed using an interactive aided-manual tracing technique. RESULTS: Total left ventricular (LV) myocardial mass ranged from 38.9 to 78.5 (mean +/- SD: 60.0 +/- 10.1) g. The mass of perfusion defect ranged from 0 to 21.4 (mean +/- SD: 12.0 +/- 5.0) g or 0 to 27% of total LV mass (mean +/- SD: 19% +/- 6%). The RT3DE estimation of total LV mass (mean +/- SD: 59.8 +/- 9.9 g) strongly correlated with the anatomic measurement (r = 0.98; y = 2.01 + 0.96x). The CE-RT3DE calculation of the mass of underperfused myocardium (mean +/- SD: 12. 3 +/- 5.3 g) also strongly correlated with the anatomic measurement (r = 0. 96; y = - 0.10 + 1.04x) and when expressed as percentage of total LV mass (r = 0.95; y = -0.20 + 1.04x). CONCLUSIONS: RT3DE with myocardial contrast opacification could accurately estimate underperfused myocardial mass in dogs of acute coronary occlusion and would play an important role in quantitative assessment of myocardial perfusion defects in patients with coronary artery disease.

Animals↗

PubMed2005

Novel polymer patterns formed by lithographically induced self-assembly (LISA).

A variety of self-assembly patterns, e.g., concentric rings, rods, and pillars, in polymer thin film have been achieved by lithographically induced self-assembly (LISA) in this study. The variations of the LISA patterns are controlled by many operation factors, such as the choice of the polymers, mask topology, process temperatures, surface tension, and so forth. It was found that as the inter- and intramolecular hydrogen bond interactions were incorporated into the polymer [poly(methyl methacrylate-co-methacrylic acid)], novel LISA patterns such as rods and corresponding arrays (concentric ring, triangle, hexagonal, etc.) were formed, in addition to the pillar arrays formed in poly(methyl methacrylate) under the same experimental conditions. The origins of the rod array are determined by the topology of the masks. Under a plain mask, the patterns developed from any nonuniform defects (spots) on the mask or polymer thin film and propagated outward. However, under a mask with protruding flat patterns, the rod patterns started along the edge of the protrusions and propagated inward. By increasing the process temperature, those novel rods and corresponding array patterns could transform back to pillar or pillar arrays.

Journal Article↗

PubMed2004

Zyxin interacts with the SH3 domains of the cytoskeletal proteins LIM-nebulette and Lasp-1.

Zyxin is a versatile component of focal adhesions in eukaryotic cells. Here we describe a novel binding partner of zyxin, which we have named LIM-nebulette. LIM-nebulette is an alternative splice variant of the sarcomeric protein nebulette, which, in contrast to nebulette, is expressed in non-muscle cells. It displays a modular structure with an N-terminal LIM domain, three nebulin-like repeats, and a C-terminal SH3 domain and shows high similarity to another cytoskeletal protein, Lasp-1 (LIM and SH3 protein-1). Co-precipitation studies and results obtained with the two-hybrid system demonstrate that LIM-nebulette and Lasp-1 interact specifically with zyxin. Moreover, the SH3 domain from LIM-nebulette is both necessary and sufficient for zyxin binding. The SH3 domains from Lasp-1 and nebulin can also interact with zyxin, but the SH3 domains from more distantly related proteins such as vinexin and sorting nexin 9 do not. On the other hand, the binding site in zyxin is situated at the extreme N terminus as shown by site-directed mutagenesis. LIM-nebulette and Lasp-1 use the same linear binding motif. This motif shows some similarity to a class II binding site but does not contain the classical PXXP sequence. LIM-nebulette reveals a subcellular distribution at focal adhesions similar to Lasp-1. Thus, LIM-nebulette, Lasp-1, and zyxin may play an important role in the organization of focal adhesions.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Experimental study of quantitative assessment of left ventricular mass with contrast enhanced real-time three-dimensional echocardiography.

OBJECTIVES: To evaluate the feasibility and accuracy of measurement of left ventricular mass with intravenous contrast enhanced real-time three-dimensional (RT3D) echocardiography in the experimental setting. METHODS: RT3D echocardiography was performed in 13 open-chest mongrel dogs before and after intravenous infusion of a perfluorocarbon contrast agent. Left ventricular myocardium volume was measured according to the apical four-plane method provided by TomTec 4D cardio-View RT1.0 software, then the left ventricular mass was calculated as the myocardial volume multiplied by the relative density of myocardium. Correlative analysis and paired t-test were performed between left ventricular mass obtained from RT3D echocardiography and the anatomic measurements. RESULTS: Anatomic measurement of total left ventricular mass was 55.6 +/- 9.3 g, whereas RT3D echocardiographic calculation of left ventricular mass before and after intravenous perfluorocarbon contrast agent was 57.5 +/- 11.4 and 55.5 +/- 9.3 g, respectively. A significant correlation was observed between the RT3D echocardiographic estimates of total left ventricular mass and the corresponding anatomic measurements (r = 0.95). A strong correlation was found between RT3D echocardiographic estimates of left ventricular mass with perfluorocarbon contrast and the anatomic results (r = 0.99). Analysis of intraobserver and interobserver variability showed strong indexes of agreement in the measurement of left ventricular mass with pre and post-contrast RT3D echocardiography. CONCLUSIONS: Measurements of left ventricular mass derived from RT3D echocardiography with and without intravenous contrast showed a significant correlation with the anatomic results. Contrast enhanced RT3D echocardiography permitted better visualization of the endocardial border, which would provide a more accurate and reliable means of determining left ventricular myocardial mass in the experimental setting.

Animals↗

PubMed2004

Real-time three-dimensional myocardial contrast echocardiography in assessment of myocardial perfusion defects.

BACKGROUND: Both real-time three-dimensional echocardiography (RT3DE) and myocardial contrast echocardiography (MCE) are novel imaging techniques. The purpose of this study was to confirm the feasibility and accuracy of RT3DE combined with MCE for quantitative evaluation of myocardial perfusion defects. METHODS: Thirteen dogs underwent ligation of the left anterior descending artery (LAD, n = 6) or distal branch of the left circumflex artery (LCX, n = 7) under general anaesthesia. Three to four ml of a perfluoropropane (C3F8) microbubble contrast agent was injected intravenously to assess the resulting myocardial perfusion defects with a commercially available Philips SONOS-7500 ultrasound system. After removal of the dog hearts, Evans blue dye was injected via the left and right coronary arteries to stain the myocardium at risk. In vitro anatomic measurements of myocardial mass after removal of the animals' hearts were used as controls. RESULTS: Left ventricular (LV) mass determined by RT3DE ranged 36.7 - 68.9 g [mean, (54.6 +/- 9.6) g] before coronary artery ligation, and correlated highly (r = 0.99) with in vitro measurement of LV mass [range, 38.9 - 71.1 g; mean, (55.6 +/- 9.3) g]. There was no significant difference between RT3DE and in vitro measurements of LV mass [range, 36.7 - 68.9 g; mean, (51.3 +/- 12.5) g. Or range, 38.9 - 71.1 g; mean, (53.7 +/- 12.3) g, respectively] and under-perfused mass [range, 0 - 21.4 g; mean, (12.0 +/- 6.9) g. Or range, 0 - 19.8 g; mean, (10.8 +/- 6.3) g, respectively] after the LAD ligation (P > 0.05). Likewise, no significant difference was present between RT3DE and in vitro measurements of LV mass [range, 50.1 - 65.4 g; mean, (57.5 +/- 5.9) g. Or range, 51.5 - 65.8 g; mean, (57.3 +/- 6.4) g, respectively] and under-perfused mass [range, 0 - 25.6 g; mean, (13.3 +/- 9.6) g. Or range, 0 - 22.7 g; mean, (12.8 +/- 8.1) g, respectively] after the LCX ligation (P > 0.05). For all the animals with coronary ligation, LV mass measured by RT3DE ranged 35.9 - 68.6 g [mean, (54.8 +/- 10.0) g] and there was no significant difference between RT3DE and in vitro measurements of LV mass and under-perfused mass (P > 0.05, r = 0.99). Further, the under-perfused mass derived from RT3DE [range, 0 - 25.6 g; mean, (12.7 +/- 8.2) g] correlated strongly with the in vitro measurements [range, 0 - 22.7 g; mean, (11.9 +/- 7.2) g] (r = 0.96). CONCLUSION: RT3DE with MCE is a rapid and accurate method for estimating LV myocardial mass and quantifying perfusion defects.

Animals↗

PubMed2004

Validation of real-time three-dimensional echocardiography for quantifying left and right ventricular volumes: an experimental study.

BACKGROUND: Assessment of the left ventricular (LV) and the right ventricular (RV) volumes and their functions is important for prognostic prediction and clinical decision making. We compared the accuracy for quantifying the LV and the RV volumes in vitro between conventional two-dimensional echocardiography (2DE) and real-time three-dimensional echocardiography (RT3DE). METHODS: The volumes of 37 rubber-models (10 regularly shaped to simulate normal LV, 7 shaped to simulate LV with symmetric aneurysm, 8 shaped to simulate LV with asymmetric aneurysm, and 12 irregularly shaped to simulate normal RV) and 10 excised canine hearts were measured by RT3DE and 2DE. On RT3DE "full volume" imaging, the inner-surfaces of the rubber-models and canine LV and RV were outlined and the volumes were measured using 2-, 4-, 8- and 16-plane methods with the RT3DE analysis software. On 2DE imaging, the volumes were measured by the Simpson method. The LV and RV volumes measured by drained water were served as reference values, with which we compared RT3DE and 2DE data. RESULTS: In rubber models mimicking normal LV and LV with symmetric aneurysms, RT3DE results were strongly correlated with reference values (r = 0.795 - 0.998) and there was a good correlation between 2DE estimates and reference values (r = 0.715 - 0.729). There were no significant differences between RT3DE estimates, 2DE results and reference values (P > 0.05). In rubber models mimicking the RV and LV with asymmetric aneurysm, RT3DE strongly correlated with reference values (r = 0.765 - 0.988), but 2DE weakly correlated with reference values (r = 0.518 - 0.592). There were no differences between RT3DE and reference values (P > 0.05), but a significant difference between 2DE and reference values occurred (P < 0.05). For excised canine hearts, there was a strong correlation between RT3DE and reference values (r = 0.728 - 0.914), while 2DE showed a less obvious correlation (r = 0.502 - 0.615). Again, there were no significant differences between RT3DE and reference values (P > 0.05), but there was a significant difference between 2DE and reference values (P < 0.05). CONCLUSIONS: RT3DE can accurately quantify LV and RV volumes and provides a new tool to evaluate LV and RV function. For LV and RV measurements by RT3DE, 8-plane strategy is the optimum choice for accuracy and convenience.

Animals↗

PubMed2004

Real-time three-dimensional echocardiography for quantifying left ventricular mass.

OBJECTIVE: To test the accuracy of real-time three-dimensional echocardiography (RT3DE) imaging system for evaluating left ventricular mass (LVM) in phantom and excised canine heart. METHODS: Ten left ventricular (LV) wall phantoms made of two rubber-bursas, ten excised canine hearts underwent RT3DE and two-dimensional echocardiography (2DE). In RT3DE "full volume" imaging, the myocardial volume was measured using 2, 4, 8, and 16-plane method with the analysis software of RT3DE. Mass was then calculated by multiplying the resulting myocardial volume by specific density of myocardial tissue. In 2DE the masses were measured by area-length method. The true LV wall phantom mass was measured by water displacement and the canine LVM was weighed by anatomy, which served as a reference standard. We compared RT3DE or 2DE with true mass. RESULTS: In LV wall phantoms, RT3DE correlated with true masses strongly (r = 0.813-0.994) and weakly correlated between 2DE and true masses (r = 0.628). In excised canine hearts, there is an excellent correlation between RT3DE and true masses (r = 0.764-0.991), while 2DE value showed a lesser correlation (r = 0.514). There are no difference between RT-3DE and true masses (P > 0.05) but different between 2DE and true masses (P < 0.05). In different planes, there was no difference between 8-plane and 16-plane (P > 0.05) but different between 8-plane and 2, 4-plane (P < 0.05). CONCLUSION: RT3DE can accurately quantify LVM and provide a new tool to evaluate LV function. For LVM by RT3DE, 8-plane measurement method is the best choice for accuracy and convenience.

Animals↗

PubMed2003

Characterization of FGFRL1, a novel fibroblast growth factor (FGF) receptor preferentially expressed in skeletal tissues.

Clones for a novel transmembrane receptor termed FGFRL1 were isolated from a subtracted, cartilage-specific cDNA library prepared from chicken sterna. Homologous sequences were identified in other vertebrates, including man, mouse, rat and fish, but not in invertebrates such as Caenorhabditis elegans and Drosophila. FGFRL1 was expressed preferentially in skeletal tissues as demonstrated by Northern blotting and in situ hybridization. Small amounts of the FGFRL1 mRNA were also detected in other tissues such as skeletal muscle and heart. The novel protein contained three extracellular Ig-like domains that were related to the members of the fibroblast growth factor (FGF) receptor family. However, it lacked the intracellular protein tyrosine kinase domain required for signal transduction by transphosphorylation. When expressed in cultured cells as a fusion protein with green fluorescent protein, FGFRL1 was specifically localized to the plasma membrane where it might interact with FGF ligands. Recombinant FGFRL1 protein was produced in a baculovirus system with intact disulfide bonds. Similar to FGF receptors, the expressed protein interacted specifically with heparin and with FGF2. When overexpressed in MG-63 osteosarcoma cells, the novel receptor had a negative effect on cell proliferation. Taken together our data are consistent with the view that FGFRL1 acts as a decoy receptor for FGF ligands.

Amino Acid Sequence↗

PubMed2003

The lipoma preferred partner LPP interacts with alpha-actinin.

The lipoma preferred partner LPP is a member of the zyxin family of proteins. In this paper, we demonstrate that the structural similarities observed between zyxin and LPP also extend to their interaction capabilities. Similar to zyxin, LPP was found to bind to alpha-actinin in vitro. This interaction was confirmed in yeast and mammalian cells. Studies utilizing the three-hybrid system further indicated that zyxin and LPP compete for the same binding site in alpha-actinin. This site was mapped to the central rod of alpha-actinin, which contains spectrin-like repeats 2 and 3. In the case of LPP, a conserved motif present at the N-terminus was shown to be responsible for the interaction. Constructs lacking this motif did not bind to alpha-actinin in the yeast two-hybrid system and were not able to recruit alpha-actinin to an ectopic site in mammalian cells. Quantitative data obtained with the two-hybrid and the three-hybrid system suggest that LPP has a lower affinity for alpha-actinin than zyxin. It is likely that this difference leads to slightly different roles played by LPP and zyxin during the assembly and disassembly of focal adhesions.

Actin Cytoskeleton↗

PubMed2003

[Clinical study on long-term treatment of primary pulmonary hypertension with continuous intravenous epoprostenol infusion].

OBJECTIVE: To observe the effects of treatment with long-term continuous epoprostenol (Epo) infusion on the survival and pulmonary artery pressure in patients with primary pulmonary hypertension (PPH). METHODS: Sixty nine patients with PPH and congestive heart failure of stage III or IV (classification by New York Heart Association) treated with Epo of initial dose of 2 - 62 ng x kg(-1) x min(-1) (the dosage was enhanced by 1 - 2 ng x kg(-1) x min(-1) every 2 months according to patient's response). All patients underwent right heart catheterization and Doppler echocardiography to measure the systolic pressure gradient between the right ventricle and right atrium (DeltaP) and the cardiac output (CO). Doppler echocardiography and catheterization data were compared. Patients were followed up with echocardiography once every 4 months. RESULTS: Of 69 patients treated with Epo 17 were followed up for > 330 days. During this period, DeltaP decreased from (84.1 +/- 24.1) mm Hg to (62.7 +/- 18.2) mm Hg (P < 0.01), CO increased from (4.00 +/- 1.22) L/min to (4.70 +/- 1.27) L/min (P < 0.02), DeltaP/CO decreased from 22.8 +/- 9.4 to 14.9 +/- 6.5 (P < 0.01). The patient survival was improved. CONCLUSIONS: Patients with PPH treated with continuous infusion of Epo experienced a decrease in pulmonary artery pressure and an increase in cardiac output. Long-term follow-up of some patients of the group demonstrated improved survival during the period of Epo therapy.

Adolescent↗