Biomedical subjects
Publications and source records attributed to S Bu.
A general method for controlling chaotic systems with one or more positive Lyapunov exponents is investigated analytically and numerically. The method retains the formal features of the adaptive adjustment mechanism and can be equally applied to various types of the unstable fixed points. It is shown that the method proposed here neither asks for any prior analytical knowledge of the system, nor any internal or external controlling parameters in advance.
A general method for stabilizing unstable discrete systems to a fixed point or high-period orbit is developed analytically and numerically in this paper. It is shown that the method can be equally applied to the systems with one or more positive Lyapunov exponents. Moreover, the method does not require a prior analytical knowledge of the system under investigation, nor any additional control parameters.
Transforming growth factor beta (TGF-beta) is an important regulator of apoptosis in some cell types, but the underlying molecular mechanisms are largely unknown. TGF-beta signals through type I and type II receptors and downstream effector proteins, termed Smads. TGF-beta induces the phosphorylation of Smad2 and Smad3 (receptor-activated Smads) which associate with Smad4 and translocate to the nucleus, where they regulate gene transcription [1]. Smad7 protein is induced by TGF-beta1 and has been classified as an inhibitory Smad. Smad7 prevents phosphorylation of receptor-activated Smads, thereby inhibiting TGF-beta-induced signaling responses [1]. Smad7 expression is increased in rat prostatic epithelial cells undergoing apoptosis as a result of castration [2]. Here we have shown that TGF-beta1 treatment or ectopic expression of Smad7 in human prostatic carcinoma cells (PC-3U) induces apoptosis. Furthermore, TGF-beta1-induced apoptosis was prevented by inhibition of Smad7 expression, by antisense mRNA in stably transfected cell lines or upon transient transfection with antisense oligonucleotides in several investigated cell lines. These findings provide evidence for a new effector function for Smad7 in TGF-beta1 signaling.
In order to find what types of hepatic cytochrome P450 (CYP) isozymes are involved in the metabolism of 2-(allylthio)pyrazine (2-AP) in rats, enzyme inducers, such as phenobarbital, 3-methylcholanthrene, dexamethasone, or isoniazid, and an enzyme inhibitor, such as SKF 525-A were pretreated. After 1-min intravenous administration of 2-AP, 50 mg/kg, to rats pretreated with SKF 525-A (a non-specific CYP inhibitor in rats), the plasma concentrations were significantly higher, and the area under plasma concentration-time curve from time zero to time infinity (AUC) was significantly greater (1365 compared with 1034 microg min/mL) as a result of significantly slower total body clearance (Cl) (36.6 compared with 48.3 mL/min/kg) than those in control rats, indicating that 2-AP was metabolized by CYP isozymes. After 1-min intravenous administration of 2-AP, 50 mg/kg, to rats pretreated with dexamethasone (an inducer of CYP3A in rats), phenobarbital (an inducer of CYP2B1/2, 2C6, 2C7, and 3A1/2 in rats), and 3-methylcholanthrene (an inducer of CYP1A1/2 and 2A1 in rats), the plasma concentrations were significantly lower, and AUC was significantly smaller (27, 41 and 60% decrease, respectively, compared with respective control rats) owing to faster Cl [37 (p>0.05), 70 (p<0.001), and 150% (p<0.001) increase, respectively, compared with respective control rats].
OBJECTIVE: To study the effect of Saikosaponin-d (SSd) on the expression of glucocorticoid receptor (GR) mRNA and cell growth in HL60 cells. METHODS: Antiproliferation effects of SSd on HL60 cells were determined by 3H-thymidine incorporation. Cell cycle analysis was also performed by flow cytometry. GRmRNA was analyzed by northern blot analysis. RESULTS: After 48 hours treatment with 10 micrograms/ml SSd, 3H-thymidine incorporation decreased in HL60 cells and the effect was time and dose dependent. The flow cytometry analysis showed HL60 cells were arrested at G0/G1 phase. The expression of GR mRNA increased. CONCLUSION: SSd exhibits the inhibition effects on cell growth in HL60 cells and could up-regulate the expression of GR mRNA in HL60 cells.
OBJECTIVE: To research the effect of saikosaponin-d (SSd) on the expression of glucocorticoid receptor (GR) mRNA and induction of apoptosis in HL-60 cells. METHODS: Antiproliferation effects of SSd on HL-60 cells were determined by 3H-thymidine incorporation. Apoptosis of the SSd-treated cells was determined by DNA fragmentation analysis and flow cytometry. GR mRNA was analyzed by Northern blot analysis. RESULTS: After 48 h treatment with 10 micrograms/ml SSd, 3H-thymidine incorporation was decreased in HL-60 cells and the effects were time and dose dependent. DNA ladder appeared after 60 h treatment with SSd. The flow cytometry analysis showed HL-60 cells was arrested at G0/G1 phase and apoptotic peak appeared in sub-G1 phase. The expression of GR mRNA was increased. CONCLUSION: SSd up-regulates the expression of GR mRNA, inhibits the cell growth and induces apoptosis in HL-60 cells.
OBJECTIVE: To explore the effect of exogenous nerve growth factor(NGF) in the regeneration of adult white rabbits inferior alveolar nerve within the silicone tubes. METHODS: In 24 adults white rabbits. A bilateral 8 mm inferior alveolar nerve gaps were created, and the proximal and distal stumps were inserted into a 12 mm silicone tube. The silicone tube of the right side was filled with exogenous NGF(experimental group) and the contralateral side was filled with saline (control group). Regeneration of the nerves was assessed by histological exam and nerve electrophysiological appreciation. Total number of the regenerating myelinated nerve fibers, the conduction velocities of nerves the thickness of myelin sheaths and the cross section area of myelinated nerve fibers between the experimental and the control groups were compared. RESULTS: The results showed that: 1. The experimental groups demonstrated more myelinated nerve fibers than that of the controls in 12 and 18 weeks. 2. At the same time following surgery, the myelin sheath thickness and the cross section area of myelinated nerves in the experimental groups were significantly greater than that in the controls. 3. In 12 and 18 weeks, the conduction velocities of regenerating nerves in the experimental groups were faster than that of the controls. CONCLUSION: This study suggested that exogenous NGF can enhance regeneration of inferior alveolar nerve with necovery of its sensory function.
OBJECTIVE: Reconstruction of laryngotracheal stenosis. METHOD: According to the pathologic condition of the larynx and trachea, various surgical procedures were designed for the treatment of laryngotracheal stenosis. These techniques included endoscopic management, laser therapy and laryngotrachoetomy with autogenous tissue and stent. RESULT: Among 36 patients, 32 were decannulated. The success rate was 88.8%. CONCLUSION: In order to improve the curation effects of laryngjotrachal stenosis, the choice of surgical procedure must be individualized to the pathologic condition of larynx and trachea, as well as the experience of the surgeon. Learning previous successful experience is also very important for a good result.
OBJECTIVE: To investigate the effect of Chinese herbal formula Gengnianjian on estrogen receptor (ER), ERmRNA substance P (SP) and beta-endorphin (beta-EP) in the hypothalamus of aging female rats. METHODS: ER proteins were determined by radioligand binding assay, ER mRNA was analyzed by Northern blot analysis and the levels of beta-EP and SP were detected by immunohistochemistry. RESULTS: In aging rats, lowered ER and ER mRNA in the hypothalamus were still up-regulated by low serum E2 level, but not in rats of after the age of 21 months; Gengnianjian significantly increased ER protein level and ER mRNA expression, decreased SP and increased the level of beta-EP in the hypothalamus in aging female rats before 21 months of age, without changing of serum E2 level. In EB group, serum E2 and beta-EP levels increased and SP level decreased but ER expression suppressed in the hypothalamus except after 21 months. CONCLUSION: Enhance estrogen bioactivity can decrease the level of SP and increase the level of beta-EP in hypothalamus of aging female rats. Herbal formula Gengnianjian increase-EP level and decrease SP level by raising the level of ER and ER mRNA.
Surgery of the anterior skull base tumor has been undertaken in 7 cases by coronal flap approach, of which 4 cases were malignant tumors and 3 cases were benign tumors. The dura became torn in 3 cases and resected in 2 cases due to tumor invasion. The dura and bony defects could be repaired with galea, pericranial flaps and fascia flaps of temporalis. The bigger bony defect was consolidated with scalp flap. Three out of 4 cases with malignant tumors were free of tumors for 6 years, 4 years and 17 months, respectively: 1 case died of tumor recurrence after 18 months. No case had postoperative complications.
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