Biomedical subjects

Hui Meng

Publications and source records attributed to Hui Meng.

29 records · Page 2Linked to original sources

PubMed2004

Effects of arterial geometry on aneurysm growth: three-dimensional computational fluid dynamics study.

OBJECT: Few researchers have quantified the role of arterial geometry in the pathogenesis of saccular cerebral aneurysms. The authors investigated the effects of parent artery geometry on aneurysm hemodynamics and assessed the implications relative to aneurysm growth and treatment effectiveness. METHODS: The hemodynamics of three-dimensional saccular aneurysms arising from the lateral wall of arteries with varying arterial curves (starting with a straight vessel model) and neck sizes were studied using a computational fluid dynamics analysis. The effects of these geometric parameters on hemodynamic parameters, including flow velocity, aneurysm wall shear stress (WSS), and area of elevated WSS during the cardiac cycle (time-dependent impact zone), were quantified. Unlike simulations involving aneurysms located on straight arteries, blood flow inertia (centrifugal effects) rather than viscous diffusion was the predominant force driving blood into aneurysm sacs on curved arteries. As the degree of arterial curvature increased, flow impingement on the distal side of the neck intensified, leading to elevations in the WSS and enlargement of the impact zone at the distal side of the aneurysm neck. CONCLUSIONS: Based on these simulations the authors postulate that lateral saccular aneurysms located on more curved arteries are subjected to higher hemodynamic stresses. Saccular aneurysms with wider necks have larger impact zones. The large impact zone at the distal side of the aneurysm neck correlates well with other findings, implicating this zone as the most likely site of aneurysm growth or regrowth of treated lesions. To protect against high hemodynamic stresses, protection of the distal side of the aneurysm neck from flow impingement is critical.

Anthropometry↗

PubMed2004

[Early-stage hemodynamic changes in dogs with gunshot wound in seawater].

OBJECTIVE: To investigate the hemodynamic changes in the early stages of gunshot wound of dogs in seawater for exploring early treatment protocol. METHOD: Fourteen conventional Beagles models undergoing gunshot wound in seawater were used along with another 2 dogs receiving the wound on land to serve as control. After the dogs were rescued from the seawater, the respiration (R), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), central venous pressure (CVP), pulmonary arterial wedge pressure (PAWP), and cardiac output (CO) were measured continuously in the early stages of the wound (53.62+/-12.19 min following injury), followed by statistical analysis of the results. RESULTS: Compared with the control group, the hemodynamic disturbance of the dogs receiving the wound in seawater was relatively severe during the first 15 min of the wound. The mortality tended to descend relevant to the position of the wounds, in the order of the head, chest, abdomen and limbs. CONCLUSIONS: Gunshot wound in seawater may cause severe hemodynamic changes, resulting in progressive dysfunction of circulation and high mortality rate. Early treatment should be targeted at hemodynamic stabilization in accordance to the characteristic changes during the early stages of the wound.

Animals↗

PubMed2003

Digital holography of particle fields: reconstruction by use of complex amplitude.

Digital holography appears to be a strong contender as the next-generation technology for holographic diagnostics of particle fields and holographic particle image velocimetry for flow field measurement. With the digital holographic approach, holograms are directly recorded by a digital camera and reconstructed numerically. This not only eliminates wet chemical processing and mechanical scanning, but also enables the use of complex amplitude information inaccessible by optical reconstruction, thereby allowing flexible reconstruction algorithms to achieve optimization of specific information. However, owing to the inherently low pixel resolution of solid-state imaging sensors, digital holography gives poor depth resolution for images, a problem that severely impairs the usefulness of digital holography especially in densely populated particle fields. This paper describes a technique that significantly improves particle axial-location accuracy by exploring the reconstructed complex amplitude information, compared with other numerical reconstruction schemes that merely mimic traditional optical reconstruction. This novel method allows accurate extraction of particle locations from forward-scattering particle holograms even at high particle loadings.

Journal Article↗

PubMed2003

Eye movements evoked by the selective stimulation of the utricular nerve in cats.

OBJECTIVE: Eye movements evoked by otolith organ are not well-investigated compare with canal related eye movements due to the technical difficulties. We try to solve this problem by means of our methods. METHODS: Eye movements evoked by selective utricular (UT) nerve stimulation were investigated using both electrooculography (EOG) and video recording in decerebrated cats in the presence or absence of anesthesia. Electrical stimulation was applied to the UT nerve through implanted acupuncture needles. RESULTS: In the absence of anesthesia and with stimulus intensities less than 2.6+/-0.7 x N(1)T, we found ipsilaterally directed horizontal eye movements in both eyes in one cat, abduction in the ipsilateral eye in two cats, and adduction in the contralateral eye in another cat. Other types of eye movements (e.g., supraduction or diagonal eye movements) were observed in both eyes of cats in the absence of anesthesia at a stimulus intensity of 12.2+/-7.6 x N(1)T, an intensity in which current spread to the adjacent nerve could not be ruled out. In the presence of anesthesia, UT nerve stimulation alone failed to evoke horizontal eye movements, but with an intensity 13.8+/-6.4 x N(1)T, supraduction or diagonal eye movements were evoked. UT nerve stimulation at 2-3 x N(1)T facilitated horizontal eye movements induced by ipsilateral abducens (AB) nucleus stimulation or contralateral horizontal canal nerve stimulation. CONCLUSION: This is the first report to our knowledge in which UT nerve-evoked horizontal eye movements are documented. These results confirm the known monosynaptic and disynaptic anatomical connections from utricular primary afferents to the ipsilateral AB nucleus neurons.

Abducens Nerve↗

PubMed2003

Intrinsic aberrations due to Mie scattering in particle holography.

Holography of small particles is a newly revived topic because of its importance in holographic particle image velocimetry (HPIV). However, the property of particle images formed through holography remains largely unexplored. This fact undermines the measurement reliability of HPIV techniques and has become one of the obstacles in the full deployment of HPIV. We study the intrinsic aberrations in the holographic particle image introduced by particle light scattering and investigate how accurately holography can deliver information about the particles that are being imaged. Consistent with our experimental observations, simulations based on Mie scattering theory show that even with a perfect hologram the reconstructed particle images demonstrate complex three-dimensional morphologies and bodily shifts. These characteristics, manifested as image aberrations, result from uneven scattering amplitude and phase distributions across the finite aperture of the hologram. Such aberrations degrade the signal-to-noise ratio in the reconstructed image as well as introducing systematic errors in detected particle image positions. We examine the effect of these aberrations on HPIV measurements.

Journal Article↗

PubMed2003

A new three-layer-funnel-shaped esophagogastric anastomosis for surgical treatment of esophageal carcinoma.

AIM: To reduce the incidence of postoperative anastomotic leak, stenosis, gastroesophageal reflux (GER) for patients with esophageal carcinoma, and to evaluate the conventional method of esophagectomy and esophagogastroplasty modified by a new three-layer-funnel-shaped (TLF) esophagogastric anastomotic suturing technique. METHODS: From January 1997 to October 1999, patients with clinical stage I and II (IIa and IIb) esophageal carcinoma, which met the enrollment criteria, were surgically treated by the new method (Group A) and by conventional operation (Group B). All the patients were followed at least for 6 months. Postoperative outcomes and complications were recorded and compared with the conventional method in the same hospitals and with that reported previously by McLarty et al in 1997 (Group C). RESULTS: 58 cases with stage I and II (IIa and IIb) esophageal carcinoma, including 38 males and 20 females aged from 34 to 78 (mean age: 57), were surgically treated by the TLF anastomosis and 64 by conventional method in our hospitals from January 1997 to October 1999. The quality of swallowing was improved significantly (Wilcoxon W=2 142, P=0.0 001) 2 to 3 months after the new operation in Group A. Only one patient had a blind anastomatic fistula diagnosed by barium swallow test 2 months but healed up 3 weeks later. Postoperative complications occurred in 25 (43 %) patients, anastomotic stenosis in 8 (14 %), and GER in 13 (22 %). The incidences of postoperative anastomotic leak, stenosis and GER were significantly decreased by the TLF anastomosis method compared with that of conventional methods (chi(2)=6.566, P=0.038; chi(2)=10.214, P=0.006; chi(2)=21.265, P=0.000). CONCLUSION: The new three-layer-funnel-shaped esophagogastric anastomosis (TLFEGA) has more advantages to reduce postoperative complications of anastomotic leak, stricture and GER.

Adult↗

PubMed2003

[Quantitative study of bacteriological infections in dogs undergoing gunshot wound in seawater].

OBJECTIVE: To investigate the changes in bacterial proliferation and the time of infection occurrence in dogs wounded by gunshot in seawater. METHOD: Fourteen canine models of gunshot wound in seawater were established, with another 2 dogs receiving the wound without seawater immersion serving as control. Gross observation and quantitative bacterial analysis were performed at 0, 6, 12 and 24 h after the injury respectively, and two dynamic models for the bacterial growth were set up on the basis of statistical analysis of the results. RESULTS: Bacterial quantity in both of the two groups tended to increase with time, but at each time point after the injury, the seawater group had higher bacterial count than the other group. Within 6 h after the injury, the bacterial count reached the critical point for clinical infection in seawater group. The two bacterial growth dynamics models were (1) Y=9.12 x 10(3+0.247X) and (2) Y=1.35 x 10(3+0.227X) for the seawater group and land group respectively, with the variant X representing time after gunshot injury, and Y the bacterial count per gram tissue. Using the dynamic models, we found that to reach the same bacteria count, the land group needed 4 h more than the seawater group(4.2 h). CONCLUSIONS: Bacterial proliferation is accelerated in the wounds in seawater to result in earlier infection onset with more severity, suggesting that early debridement within 4 h after the injury, complete washing of the wound and early administration of the antibiotics are necessary for the wound management.

Animals↗

PubMed2003

[Lung transplantation for treatment of pulmonary cystic fibrosis: report of one case].

A right single lung transplantation was performed in a 17-year-old female patient with end-stage cystoid pulmonary fibrosis and without cardiopulmonary bypass in June 2003. The donor lung was perfused with cold UW solution with a cold ischemic time of 280 min. The patient weaned from ventilator on the next day of operation (18 h later) and was able to walk at the fourth day postoperatively. Immunosuppression included methylprednisolone used before FK 506, mycophenolate mofetil and prednisone dosed after operation. The patient remains well a month after operation with significant improvement of the lung function and enjoys normal life.

Adolescent↗

PubMed2002

Morphology of physiologically identified otolith-related vestibular neurons in cats.

The morphology of physiologically identified otolith nerve-activated vestibular neurons was investigated using intracellular injections of horseradish peroxidase (HRP). Eleven utricular, 11 saccular and three utricular/saccular nerve-activated vestibular neurons were labeled with HRP. All of these neurons except one were secondary neurons, the exception being a convergent neuron. The labeled neurons were pyramidal, elongated and ovoidal in shape. Most of the labeled cells were medium to large (mean diameter: > or =30 micro m). There was no apparent correlation between morphology and the different types of otolith nerve-activated vestibular neurons. Thus, it seems likely that the functional type of vestibular neurons cannot be presumed on the basis of their morphology alone.

Animals↗

PubMed2002

Morphological changes in canine lungs perfused with modified Euro-Collins solution.

OBJECTIVE: To investigate the structural changes in canine lungs perfused with modified Euro-Collins solution (mECS), thus providing insight into the preservation of the donor lung tissue for transplantation. METHODS: Six dogs were anesthetized and pulmonary perfusion with mECS (4 degrees Celsius) was performed before the lungs were isolated thereafter and stored at 4 to 8 degrees Celsius for 30, 60, 120, 180, 240 min respectively, after which tissue samples of the donor lung were taken for morphological observation with both light and transmission electron microscope. RESULTS: Immediately after reperfusion, the pulmonary tissues exhibited clear and intact structures,showing that mitochondrion swelled slightly in the alveolar epithelial cells (AECs). Mild edema occurred in the alveolar wall and the tissues around the veins at 30 min after preservation, which exacerbated to dilapidation of the alveolar wall and obvious tumefaction of the mitochondrion in the AECs at 60 min. At 180 min, rupture of alveolar wall and emergence of the alveolus was observed at 120 min, and a few pulmonary bullae were formed, the AECs (I) of which presented vacuolar changes in the cytoplasma and mitochondrion, with disappearance of the tiny villus of the AECs (II) at 240 min. CONCLUSION: Within 4 h of preservation in mECS, the pulmonary tissues do not undergo obvious changes as signs of injury, which, however, may not be the case after longer preservation.

Animals↗

PubMed2002

[Effect of jinshui-liujun decoction on chronic bronchitis in rats].

OBJECTIVE: To study of the quality standard about Jinshui Liujun decoction. METHODS: The chronic broncitis model of rat was induced by injecting LPS into rat's trachea. Then, the number of WBC, SV, PS were detected. RESULTS: Both Jinshui Liujun decoction and hesperidin can improve the content of PS and reduce the number of WBC. There were statistical difference between the therapeutic groups and the model group, and the changes of bronchi between the therapeutic group were similar. But the SV of hesperidin group was bigger than Jinshui Liujun decoction group, and the PS of hesperidin group was less than Jinshui Liujun decoction group. CONCLUSION: It was feasible that the content of hesperidin in Jinshui Liujun decoction was as primary quality control index.

Angelica sinensis↗