Biomedical subjects

W Ren

Publications and source records attributed to W Ren.

At least 19 recordsLinked to original sources

PubMed2004

A novel murine model of orthopaedic wear-debris associated osteolysis.

OBJECTIVE: To develop a mouse model of bone resorption to quantitatively evaluate wear-debris induced osteolysis. METHODS: Air pouches were established on the back of BALB/c mice, followed by the surgical introduction of a section of femur or calvaria from a syngeneic mouse donor. One group of bone-implanted pouches was stimulated with ultra-high molecular weight polyethylene (UHMWPE) debris, and the remaining bone-implanted pouches received saline alone as controls. The tissues were harvested at 2, 7, and 14 days after bone implantation for molecular and histological analyses. RESULTS: Marked inflammatory responses (thicker membrane and increased cellular infiltration) were observed in UHMWPE-stimulated pouches, compared with the saline control. Intensive tartrate-resistant acid phosphatase (TRAP) staining was identified in the UHMWPE-stimulated pouches, especially at the attachment site of inflammatory tissue with implanted bone, where active osteolysis occurred. Image analysis showed that the bone collagen loss was closely related to the amount of UHMWPE within the tissue, and was most prevalent at the contact site of bone with inflammatory tissue. UHMWPE stimulation also significantly increased the release of free calcium into the pouch fluids. CONCLUSION: This model demonstrates a sensitive, rapid, and reproducible method for studying wear-debris induced osteolysis seen in patients with aseptic loosening.

Animals↗

PubMed2001

Different classifications of UPOs in the parametrically different chaotic ISI series of a neural pacemaker.

Various interspike intervals (ISIs) in a series of spontaneous discharges of experimental neural pacemakers were identified as chaotic and as lying between stable period 2 and stable period 3. The method of So et al. for detection of unstable periodic orbits (UPOs) was applied to analyze two chaotic ISI series generated under the action of [Ca2+]o in different concentrations. In the chaotic ISI series near the stable period 2, an unstable period 2 orbit was detected. In the chaotic ISI series near the stable period 3, both an unstable period 2 orbit and an unstable period 3 orbit were detected. The location of the unstable period 2 orbit was close to that of the stable period 2 in the return map, while the location of the unstable period 3 orbit was close to that of the stable period 3. The results not only revealed the structures of various chaotic ISI series, but also indicated that the classification of UPOs could reflect the experimental control parameters at which the chaotic ISI series were generated. The previously discovered period adding bifurcation in the ISI series generated by experimental neural pacemakers [12] was further described in terms of the evolution of the period orbits.

Action Potentials↗

PubMed2001

Tartary buckwheat flavonoid activates caspase 3 and induces HL-60 cell apoptosis.

It has been proposed that flavonoids may have potential as anticancer agents. In this study, we showed that tartary buckwheat flavonoid (TBF) obviously inhibits the growth of human acute myelogenous leukemia (AML) HL-60 cells by MTT assay. The inhibitory effect of TBF on the proliferation of HL-60 cells is related to the induction of apoptosis, which is confirmed by DNA ladder formation on gel electrophoresis and apoptosis morphological changes under light microscope. Furthermore, HL-60 cells undergo rapid apoptosis upon treatment with TBF, as indicated by increased annexin V binding capacity and caspase 3 activation with flow cytometric analysis. Thus, our data provide a potential mechanism for the chemopreventive activity of tartary buckwheat flavonoid and suggest that it may have a potentially therapeutic role for human leukemia.

Annexin A5↗

PubMed2001

Nucleotide sequence analysis of a transforming gene isolated from nasopharyngeal carcinoma cell line CNE2: an aberrant human immunoglobulin kappa light chain which lacks variable region.

A transforming gene, designated Tx, was isolated from a human nasopharyngeal carcinoma (NPC) cell line CNE2 by transfection and molecular cloning techniques. The Tx gene was analyzed using computer-based bioinformatics and compared with the known sequences in EMBL and GenBank databases. We found that Tx contains human immunoglobulin kappa light chain constant region, five intact joining regions J1-J5, five recombination signal sequences and an N-segment besides classic regulatory sequences such as TATA boxes, CAAT boxes, poly A signals, etc. Interestingly, Tx also contains several binding sites for nuclear transcription factors such as NF-kappaB, NF-IL6, TFIID, etc. In conclusion, there are only several base pairs mutations or deletions compared with normal Ig K JC gDNA fragment. In all, Tx is an aberrant human immunoglobulin kappa light chain that contains the constant region, five joining regions, which lacks the variable regions.

Genes, Immunoglobulin↗

PubMed2001

Changes in vasoreactivity of rat pulmonary artery after 7 d tail-suspension.

OBJECTIVE: To clarify the effects of simulated microgravity on the local regulating function of the pulmonary circulation. METHOD: Rat tail-suspension (TS) was used as the animal model to simulate the effects of microgravity. The changes in responses of pulmonary artery to several vasoactive agents were determined by using in vitro vessel rings perfusion technique. RESULT: As for the endothelium-intact vessel rings from TS group compared with those from the control (C) group, the contractile responses of pulmonary artery to potassium chloride (KCl, 10 ~ 70 mmol/L) did not change obviously after 7 d tail-suspension, which were markedly diminished as to phenylephrine (PE, 10(-9) ~ 10(-5) mol/L). The vasodilatory responses to acetylcholine (ACh, 10(-9) ~ 10(-5) mol/L) were markedly enhanced, which did not change obviously as to captopril (Cap, 10(-5) ~ 3 x 10(-3) mol/L). The vasoreactivity of endothelium-removed pulmonary artery rings to all vasoactive agents did not change after 7 d tail-suspension as compared with those from control rats. CONCLUSION: The release of nitric oxide (NO) by rat pulmonary arterial endothelium was enhanced after 7 d tail-suspension. The vasodilatory function of pulmonary artery was enhanced.

Acetylcholine↗

PubMed2001

[Changes of arterial blood pressure during various stages in spaceflight activities].

Arterial blood pressure (BP) is one of the four life signs in human beings, it could reflect cardiovascular function in some degrees. Thus, BP serves as an important cardiovascular parameter during various stages in foreign spaceflight activities. Although the reports about BP are not always in consistency during spaceflight, hypotension commonly occurs during orthostatic stress after spaceflight. The mechanisms of orthostatic intolerance after spaceflight are virtually the same as that of orthostatic hypotension after spaceflight. This paper simply reviewed the reports on BP during various stages in foreign spaceflight activities and the researches on the mechanism of orthostatic hypotension after spaceflight.

Aerospace Medicine↗

PubMed2001

[Experimental study on repair of bile duct defects with expanded polytetrafluoroethylene].

OBJECTIVE: To explore the possibility of repair of the extensive bile duct injuries with expanded polytetrafluoroethylene (ePTFE). METHODS: A total of 36 local healthy hybrid dogs were employed to establish bile duct injury models by means of partial removal of bile duct (group A, 14 dogs), excision of a segmental duct (group B, 10 dogs), and ligation of the lower part of common bile duct(group C, 5 dogs; group D, 7 dogs). Group A were patched with ePTFE mesh, group B replaced by ePTFE tube. Interposition of the grafts between gallbladder and duedenum or jejunum was performed on group C and group D. The animals' postoperative performance status were evaluated. Cholangiography was used to define the patency of bile ducts. Tissues of bile ducts and liver were taken at 3 days, 2, 4, 8, 12 and 52 weeks for microscopic and ultrastructural examination to observe the healing process of bile duct and morphological changes in the liver. RESULTS: Group A with ePTFE patch covered by epithelium had a high patency rate of 75%(9/12) and pathological damages were not found in the liver. The patency rate of group B was merely 40%(4/10), to some extent, accompanying damages in the liver. The grafts of group C and group D were fully expelled, ultimately leading to cystic-duodenal or cystic-jejunal fistulas formation. CONCLUSION: The study suggests that application of ePTFE patch to repair bile duct defects is feasible.

Animals↗

PubMed2001

[Changes of brain potentials related to auditory location discrimination during simulated weightlessness].

Objective. To study changes of brain response in distinguishing auditory location during simulated weightlessness. Method. The event-related potentials (ERPs) during auditory location discrimination were compared between head down tilt (HDT) and head up tilt (HUT) conditions among 14 healthy subjects. Result. (1) Both the target (T) and non-target (NT) auditory signals induced significant ERPS; (2) The slow potential was significantly lower for both T and NT-ERPs during HDT as compared with that during HUT; (3) The reduction of mean slow potential amplitude during HDT was more significant for the target signals from right-rear position and lightest for the target signals from right-front position. This phenomenon was more remarkable at left-front area. Conclusion. These data provide further evidence that the higher brain function was affected by simulated weightlessness.

Aerospace Medicine↗

PubMed2001

[The dynamic changes of NOSmRNA in endothelial cells of aortae and pulmonary arteries in rats under tail suspension].

Objective. Through the observations of dynamic changes of eNOSmRNA and iNOSmRNA in arterial endothelial cells of systematic circulation and pulmonary circulation under simulated weightlessness, to collect some data for studies of the adaptive mechanisms of local regulation in arterial systems. Method. Wistar rats were -30 degrees tail suspended to simulate the effects of weightlessness. The rats were randomly divided into three groups: control group (CON), 7-day tail suspension group (TS7) and 14-day tail suspension group (TS14). Changes of NOSmRNA expresses in endothelial cells of the thoracic aortae and pulmonary arteries were observed with in situ hybridization technique. Result. The eNOSmRNA and iNOSmRNA of thoracic aortic and pulmonary arterial endothelial cells in TS7 rats increased very significantly. The eNOSmRNA of thoracic aortic endothelial cells from TS14 rats returned to control level, but remained very significantly increased in pulmonary arteries. The iNOSmRNA in pulmonary arterial endothelial cells from TS14 rats decreased very significantly, but that in thoracic aortae returned to the control level. Conclusion. The responses of eNOSmRNA and iNOSmRNA in arterial endothelial cells of systematic circulation to tail suspension were similar, but they were different in pulmonary arterial endothelial cells, which might be due to the difference in the peak course of the shift of fluid from lower body entering the pulmonary or systematic circulation during initial period of simulated weightlessness. It could be a kind of important sign of depressed local regulative function under simulated weightlessness and might contribute to orthostatic intolerance after simulated weightlessness.

Animals↗

PubMed2001

[Changes of early components of auditory ERPs during HDT-simulated weightlessness].

Objective. To study changes of early components of the auditory ERPs during simulated weightlessness. Method. The event-related potentials (ERPs) during an auditory location discrimination were compared between head down tilt (HDT) and head up tilt (HUT) conditions in 14 normal subjects. Result. The early components of T-ERPs and NT-ERPs decreased significantly during HDT as compared with that during HUT. The reduction of mean potential amplitude during HDT was more marked at left-forehead area (F5). Conclusion. These data provided further evidence showing that the early activity process of brain was also affected by simulated weightlessness.

Adult↗

PubMed2001

[Application of degree of complexity in heart rate variability analysis during orthostatic (correction of orthosatic) standing].

Objective. To introduce the degree of complexity in characterizing heart rate variability (HRV), and to discuss the changes in complexity of the cardiovascular system during orthostatic standing posture. Method. ECG of 8 subjects were recorded during supine and orthostatic standing postures. Degree of complexity was used to analyze the HRV. Result. Compared to supine before orthostatic standing posture, R-R intervals and its standard deviation at 0-5 min, 5-10 min, 10-15 min and 15-20 min during orthostatic standing posture were decreased significantly; the degree of complexity of HRV at 0-5 min and 15-20 min during orthostatic standing posture were decreased significantly; the approximate entropy of 0-5 min and 15-20 min were decreased significantly. Conclusion. The results showed that HRV and complexity of cardiovascular system was decreased during orthostatic standing. It was feasible that the degree of complexity can be used to analyze HRV.

Adolescent↗

PubMed2001

[Effects of adaptive changes of vestibular system on cardiovascular regulation and orthostatic tolerance].

Astronauts may experience Space Adaptation Syndrome at the primary period in spaceflight. It is widely accepted that it is mainly caused by vestibular adaptive changes. The reverse changes of adaptation present after the return from weightlessness to normal 1 G. It may cause astronauts' postural instability and orthostatic intolerance. Evidences from animal model and some data from humans suggest that the vestibular system have influences on the sympathetic nervous system and cardiovascular control. The inputs that appear to be critical in producing these responses come from otolith receptors. The important medical problem--orthostatic intolerance in space medicine is mainly caused by cardiovascular abnormal control. It is possible that vestibular adaptive changes under microgravity may have its influence on the cardiovascular function and orthostatic intolerance.

Adaptation, Physiological↗

PubMed2000

[The progress in research on the mechanisms of the effects of blood volume reduction on orthostatic tolerance after microgravity or simulated microgravity].

Orthostatic intolerance commonly occurs after spaceflight, but its mechanisms remain to be clarified. It is believed that the reduction of blood volume might be one of the important factors. So the current countermeasures against orthostatic intolerance are aimed to control the changes of blood volume. The main differences between physiological effects of microgravity and simulated microgravity on humans appear in the circulation of the low pressure side and in humoral and electrolyte metabolism. Reflexes elicited from the low pressure side are very important for regulation of the extracellular fluids. The authors postulated that for a further understanding of mechanisms of orthostatic intolerance after spaceflight and to establish appropriate countermeasures against orthostatic intolerance, it is important to study the course of changes of the circulation in the low pressure side and the reflexes thus elicited with more appropriate method of simulation.

Adaptation, Physiological↗

PubMed2000

[EEG synchronization index spectrum: definition, calculation and the changes related to visual selective response].

OBJECTIVE: EEG synchronization is usually estimated in terms of coherence amplitude, but the estimation is with apparent uncertainty because of the poor resolution both in time and frequency. The purpose of this work is to surmount this problem. METHOD: A new definition of EEG synchronization index spectrum [SynI(f)] was developed basing on the distribution characteristics of EEG coherence phase which was calculated by a tested algorithm with 1 s and 1 Hz resolution. The basic feature and its changes during visual selective responses were calculated in 25 normal subjects. EEG signals were recorded from 9 locations in two conditions: looking at the central LED only(VC) and making switch response to the target LED flash signals (T) differentially (DR): switch to left or right for Ts from left (LVF) or right (RVF) visual field, repectively but making no response to the non-target ones (NT). RESULT: (1) The frequency dependency of SynI varied with brain location, e.g., SynI was higher in alpha range than others at frontal locations but the situation reversed at posterior locations. (2) The SynIs between midline and right brain locations were higher than that between mid line and left ones. (3) As compared with VC, SynI was increased in DR condition at central and posterior brain locations but not frontal ones, it happened mainly in 7-23 Hz at central locations but in 1-4 Hz at posterior ones. (4) The augmentation of SynI in DR was greater for T than for NT signals. CONCLUSION: The results indicated that the SynI(f) was meaningful for studying the frequency-spatial feature of EEG synchronization change among brain locations related to cognitive activities.

Aerospace Medicine↗

PubMed2000

Unsymmetrical response features of left and right brain to signals from left and right visual fields at different cognitive levels.

OBJECTIVE: To study the response characteristics of left and right brain to signals from left (LVF) and right (RVF) visual fields during cognitive activity. METHOD: ERPs at 9 locations to LVF and RVF signals were compared in 23 normal subjects in 3 task conditions: looking forward only (VC); making switch response to target signals (T) only (SR); making switch response to T differentially (DR). RESULT: (1) Significant difference in ERPs was found between that induced by LVF and RVF signals on left brain especially at frontal location (F5), which appeared as slow negative deflection induced by T and NT from RVF in SR and DR; (2) Condition-dependent unsymmetrical features between left and right brain were found: the slow potential at F5 was significantly more negative in T and contralateral spatial relation (i. e., left brain for RVF) but more positive in NT and ipsilateral relation than that at F6. CONCLUSION: Signals with psychological meaning in RVF might cause more psychological load as suggested by the results obtained in this study.

Adult↗

PubMed2000

[Analysis and improvement consideration of the current human experimental models of humoral regulation in microgravity].

The main differences between physiological effects of microgravity in spaceflight and simulated microgravity on humans appeared in the circulation of the low pressure side, in humoral and electrolyte metabolism. For a further understanding of the physiological effects of microgravity, some improvement of the current human experimental models are needed. It is possible to choose more adequate models closer to the situation in microgravity through measuring cardiovascular parameters, fluid regulation and renal excretion variables under head-up tilt (HUT) plus lower body positive pressure condition, or under head-down tilt (HDT) plus upper body negative pressure in various angles and pressure levels.

Adaptation, Physiological↗

PubMed2000

[Approximate entropy and its application in heart rate variability analysis].

Objective. To introduce approximate entropy in the analysis of heart rate variability, and to discuss the changes of the complexity of cardiovascular system during orthostatic standing posture. Method. ECG of 8 subjects were recorded during supine and orthostatic standing postures. Approximate entropy was used to analyze HRV. Result. Compared to supine before orthostatic standing posture, R-R intervals at 0-5 min, 5-10 min, 10-15 min and 15-20 min during orthostatic standing posture were decreased significantly, while approximate entropy at 0-5 min and 15-20 min decreased significantly. It showed that the complexity of cardiovascular system was decreased and the modulation of cardiovascular system changed. Conclusion. It is feasible that approximate entropy be used for heart rate variability analysis.

Adolescent↗

PubMed2000

[Changes in electrocardiogram and cardiac phase during various stages in foreign manned spaceflight activities and the analysis of their possible mechanisms].

Electrocardiography (ECG) is still the only method for continuous medical observation during various stages of foreign manned spaceflight activities, and it also serves as an important item for medical monitoring in the project for manned spaceflight activities in our country. With electrocardiography, pulse or heart rate (one of the four life signs) and cardiac function can continuously be observed. Cardiac phase relative to ECG is a main index reflecting cardiac function. Understanding of the results of ECG and cardiac phase and their mechanisms during various stages of foreign manned spaceflight activities will be helpful in establishing emergency measures in the course of manned spaceflight activities in our country.

Aerospace Medicine↗