Biomedical subjects

Jing Bai

Publications and source records attributed to Jing Bai.

28 records · Page 2Linked to original sources

PubMed2004

Model of depressed myocardium shows orthostatic intolerance with or without reduced blood volume.

INTRODUCTION: The development of orthostatic hypotension (OH) is complex and multi-factorial. Previous simulation work indicates that myocardial contractility depression (MCD) may increase OH when there is a total blood volume decrease. This paper hypothesized that MCD increased OH in both humans with and without decrease in blood volume. METHODS: A model, which was previously used to reproduce cardiovascular response to lower body negative pressure (LBNP), hypovolemia, and MCD, was modified by incorporating the physiologic mechanism of plasma filtration into the interstitium during LBNP. The model was evaluated by human experimental results. Using the model, HR and BP response to LBNP were simulated at conditions of 10%, 20%, and 30% MCD. Additionally, HR and BP response to LBNP were simulated at conditions of 10% and 20% MCD with a 12% decrease in blood volume. RESULTS: Simulation results indicate that the increments of HR and decrements of systolic BP (SBP) and mean arterial pressure (MAP) rise with the increases of MCD. Specifically, simulation results indicate that about 30% MCD would cause OH (HR: 117 bpm; SBP: 92 mmHg; MAP: 78 mmHg). It also indicates that about 20% MCD would cause OH (HR: 134 bpm, SBP: 84 mmHg, MAP: 73 mmHg) with a 12% decrease in total blood volume. CONCLUSION: It is suggested that MCD increases OH whether or not there is a total blood decrease, and further suggested that MCD induced by both spaceflight and heart disease may increase OH.

Adult↗

PubMed2004

[Development of a portable ECG monitor based on TMS320VC5402].

OBJECTIVE: To develop a portable ECG monitor with top performance. METHOD: The hardware system and control program were designed basing on a digital signal processor TMS320VC5402. An algorithm of arrhythmia detection was embedded. RESULT: Four types of arrhythmia could be detected. Seven sections of 64 k-byte ECG data could be stored and the collection time of each segment was marked. The ECG data recorded could be sent to the hospital via either digital or analog method. With low power consumption and rechargeable Li+ battery, this monitor could work continuously. CONCLUSION: The monitor meets the design requirements and possesses excellent practicability.

Arrhythmias, Cardiac↗

PubMed2003

[Allogeneic hematopoietic stem cell transplantation for beta-thalassemia major].

OBJECTIVE: To investigate the effect of hematopoietic stem cell transplantation (HSCT) for beta-thalassemia major. METHODS: Fifteen beta-thalassemia major patients with a median age of 3. 5 years (range 1 - 10 years) received allogeneic HSCT. According to the Pesaro's classification for thalassemia, 12 patients were grade I - II, and 3 grade III. The bone marrow transplantation (BMT) plus peripheral blood stem cell (PBSC) transplant mobilized by granulocyte colony-stimulating factor (G-CSF) was used when donor is low body-weight. RESULT: Of the fifteen patients, nine were disease-free survival (DFS) at a median follow-up of 2.5 years (range 6 - 54 months). Of eight grade I - II patients received HLA identical sibling BMT, seven were DFS, and of two received HLA mismatched marrow from their mother, one DFS, another not engrafted. Two patients received unrelated cord blood HSCT were both not engrafted. Two patients received PBSC transplantation alone were not engrafted, but one of them soon received BMT from the same donor and was DFS. The incidences of grade I - II and grade III acute graft-versus-host disease (aGVHD) were 20% (3/15) and 6.7% (1/15), respectively. Interstitial pneumonia occurred in 4/15 (26.7%) patients. There were no long-term complications in the survivors. CONCLUSION: Grade I - II beta-thalassemia major patients received HLA identical sibling BMT had higher DFS. It was propitious for engraftment to use BMT plus PBSC, but with a higher incidence of acute and chronic GVHD.

Child↗

PubMed2003

[Preliminary experimental analysis of myocardial function evaluation based on integrated backscatter].

OBJECTIVE: To demonstrate the feasibility of the method to detect myocardial function based on integrated backscatter. METHOD: Using the experimental system developed by our research group, the RF signal of B-mode image was sampled and digitized. Wavelet transform method was adopted for cyclic variation of integrated backscatter (CVIB) calculation. The CVIB image of the region of interest (ROI) was obtained. RESULT: The CVIB results of 11 cases with myocardial infarction were provided by data and image. Results of 23 normal people including 8 middle-aged and 15 young were also given for comparison. CONCLUSION: The method based on integrated backscatter can differentiate ischemic myocardium from normal people and it has potential to be used in clinic.

Adolescent↗

PubMed2003

[An experimental study on airway inflammation and remodeling in a rat model of chronic bronchitis and emphysema].

OBJECTIVE: To study the pathological features of airway inflammation and remodeling in rats with chronic bronchitis (CB) and emphysema and to evaluate the protective and therapeutic effects of erythromycin (EM). METHODS: Forty-three Wistar rats were assigned to eight groups: normal control group (A group, n = 5), normal saline solution group (P group, n = 5), CB group (L group, n = 6), CB and emphysema group (S group, n = 6), low-dose EM-treatment group (E(1) group, n = 5), high-dose EM-treatment group (E(2) group, n = 6), low-dose EM-prevention group (E(10) group, n = 5) and high-dose EM-prevention group (E(20) group, n = 5). The rat model of CB and emphysema was established by intratracheal instillation of lipopolysaccharide (LPS) and daily exposure to cigarette smog. After four weeks, total and differential cell counts in bronchoalveolar lavage fluid (BALF) were observed, and the pathomorphological changes in the lung were analyzed. The thickness of the smooth muscles and collagen in the bronchial wall were measured. Expression and localization of transforming growth factor beta(1) (TGF-beta(1)) were observed in the bronchi and lung tissues by immunohistochemistry. The levels of hyaluronic acid (HA) and procollagen type III (PCIII) in the serum and BALF were determined by the radioimmunoassay (RIA). RESULTS: (1) Compared with A group [(0.9 +/- 0.7) x 10(5)/ml], absolute neutrophil count in BALF from S group [(17.1 +/- 10.8) x 10(5)/ml] were significantly higher (P < 0.01). (2) Both the pathologic scores obtained from the S group (329 +/- 114) and P group (67 +/- 25), and the thickness of smooth muscles and collagen from S group [(9.6 +/- 2.6)%] and A group [(6.1 +/- 1.8)%] were statistically different (P < 0.01, P < 0.05, respectively). Expression of TGF-beta(1) in the lung of S group was significantly higher than that in A group. (3) The levels of HA [(152.5 +/- 36.3) micro g/ml] and PCIII [(40 +/- 8) micro g/ml] in serum and the levels of HA [(94 +/- 35) micro g/ml] and PCIII [(39 +/- 7) micro g/ml] in BALF in S group were higher than those in A group (P < 0.01). (4) After treatment with 100 mg/kg EM, absolute neutrophil count in BALF, the pathologic scores, the thickness of smooth muscles and collagen in the bronchi, the levels of PCIII and HA in serum and the levels of PCIII and HA in BALF were reduced to (2.1 +/- 1.4) x 10(5)/ml, 187 +/- 61, (6.0 +/- 2.3)%, (9.69 +/- 5.61) micro g/ml, (63.0 +/- 11.6) micro g/ml, (16 +/- 6) micro g/ml, (52 +/- 12) micro g/ml, respectively. Statistical analysis revealed that there were significant differences as compared to those of group S (P < 0.05). CONCLUSIONS: Many inflammatory cells especially neutrophils and alveolar macrophages might play an important role in the airway inflammation of CB and emphysema. Thickening of smooth muscles and collagen in the bronchi and the excessive depositions of extracellular matrix (ECM) constitute the fundamental pathological characteristic of airway remodeling in CB and emphysema. EM may prevent airway inflammation and remodeling to some degree.

Animals↗

PubMed2002

Simulation study of the cardiovascular functional status in hypertensive situation.

An extended cardiovascular model was established based on our previous work to study the consequences of physiological or pathological changes to the homeostatic functions of the cardiovascular system. To study hemodynamic changes in hypertensive situations, the impacts of cardiovascular parameter variations (peripheral vascular resistance, arterial vessel wall stiffness and baroreflex gain) upon hemodynamics and the short-term regulation of the cardiovascular system were investigated. For the purpose of analyzing baroregulation function, the short-term regulation of arterial pressure in response to moderate dynamic exercise for normotensive and hypertensive cases was studied through computer simulation and clinical experiments. The simulation results agree well with clinical data. The results of this work suggest that the model presented in this paper provides a useful tool to investigate the functional status of cardiovascular system in normal or pathological conditions.

Blood Pressure↗

PubMed2002

Estimation and reduction of decorrelation effect due to tissue lateral displacement in elastography.

In cross-correlation based elastography, the quality of the strain image is degraded by the distortion of echo waveforms due to tissue axial and lateral displacement. To study the effects of tissue lateral displacement on echo decorrelation, a tissue axial stretching model is developed and a concept called correlation signal-to-noise ratio (CSNR) is introduced to quantify the decorrelation effect due to tissue lateral displacement. A computer simulation based on the tissue stretching model is carried out to study the influence of several important elastographic parameters on echo decorrelation due to tissue lateral displacement. Finally, guided by the CSNR concept, a 2-dimensional (D) spatial comprehensive cross-correlation method is proposed to reduce the decorrelation noise. Results indicate that CSNR can be used as a quality indicator of elastography and the 2-D spatial comprehensive cross-correlation method can effectively reduce the decorrelation noise while slightly decreasing the lateral resolution of the strain image.

Algorithms↗

PubMed2002

[The changes of cardiovascular response to orthostatic stress caused by hypovolemia induced by weightlessness: a simulation study].

We introduced the method of computer simulation in the studies of gravitational physiology. Based on work of Melchior (1994), we developed a mathematical model that can be used to stimulate cardiovascular responses to orthostatic stress (lower body negative pressure, LBNP). The model includes 7 sub-models: the redistribution of blood, the filling of left ventricle, left ventricle working, peripheral circulation, control of heart rate (HR), control of peripheral resistance and control of venous tone. Then we simulated the changes of blood pressure (BP) and heart rate during lower body negative pressure, and the results agreed well with the results of our human experiment. By using the developed model, we also simulated the effects of hypovolemia on the BP, HR and shock index during orthostatic stress. The simulation results indicate that the cardiovascular responses to orthostatic stress change significantly when the decrease of blood volume is more than 15% of the total blood volume. However, if the amount of the decrease of blood volume is less than 5% of the total blood volume, HR and BP could be maintained in normal range by the regulation of baroreflex during LBNP. Our simulation results suggest that hypovolemia may be the main cause of orthostatic intolerance induced by weightlessness.

Adult↗

PubMedDate not supplied

Patterns of brain activation in patients with mild Alzheimer's disease during performance of subtraction: an fMRI study.

We performed a functional MRI (fMRI) study to compare the difference of activation between healthy aged people and patients with mild Alzheimer's disease (AD) during performance of subtraction. Nine patients with mild AD and nine healthy aged volunteers were recruited in this study. The analysis of fMRI data revealed that brain activation is decreased in several regions in AD patients in comparison with healthy participants. But in the right inferior prefrontal lobe, activation is greater in patients than in the controls. We believe that our findings will help the understanding mechanism of neuronal activity in AD.

Aged↗

PubMedDate not supplied

Locating inhomogeneities in tissue by using the most probable diffuse path of light.

Characterization of human tissue using near-IR (NIR) light is becoming increasingly popular. The light signal transmitted from the tissue contains information concerning inhomogeneities in tissue, such as size, position, and pathological states (benign or malignant). We discuss the most probable diffuse path (MPDP) related to frequency-domain diffuse photon density waves (DPDWs) propagating inside turbid media. We find that for a medium of finite size, the existence of boundaries between tissue and nonscattering media would have considerable impact on the path shape. It is also demonstrated that such paths can be used to obtain higher accuracy in localizing absorbers embedded in a homogeneous background. Based on the proposed MPDP, a new method for 3-D localization of heterogeneities in turbid media is proposed, which is validated by experiments using Intralipid and pork fat. The experiments are performed with an NIR breast cancer detection system designed and assembled in our lab, using 780-nm NIR light. In Intralipid, when the size of a single absorber is less than 1 cm, the localization error is about 2 mm. The results from pork fat are also acceptable.

Adipose Tissue↗