Biomedical subjects

S Xu

Publications and source records attributed to S Xu.

At least 109 records · Page 6Linked to original sources

PubMed2001

Static magnetic field effects on bone formation of rats with an ischemic bone model.

Effects of a static magnetic field were studied on bone formation using an ischemic rat femur model. Metal rods were prepared from magnetized and unmagnetized samariun cobalt to have tapered structure, both with the same geometrical dimension, and were implanted transcortically into the middle diaphysis of 88 rat femurs. Both sides of the rat femoral artery were ligated to create an ischemic bone model, followed by implantation of the tapered rod to the femur. The bone mineral density (BMD) and weight of the femurs were measured at 1st and 3rd week after implantation. The result at the 3rd week post-implantation revealed that the BMD and weight of the ischemic bone model rats were significantly reduced, compared with that of non-operated femur. It was also found that the magnetized group had significantly higher bone weights than the unmagnetized (p<0.05). The BMD of the rats implanted with the magnetized rods were similar to those of the non-operated (p>0.05). This enhancement of the femoral bone formation of the ischemic rat model by the static magnetic field seems to be due to the improved blood circulation of the femur.

Animals↗

PubMed2001

[Effects of surface pattern of polymers on adhesion characteristics of transformed human embryonic tendon cells].

Effects of surface pattern of polymers on adhesion characteristics of transformed human embryonic tendon cells (THETCs) have been examined by using a micropipette aspiration technique, which is a cellular mechanical method. The results showed that the adhesion characteristics of THETCs depend on the surface pattern of polymers, and the adhesion force of THETCs to porous films is higher than that to non-porous films and fibers. The adhesion force bears relationships with the aperture of porous films and has a stronger dependence on the large aperture (150-500 microns) than on the small aperture (< 150 microns) of porous films. The adhesion force of THETCs to fibers is increased slightly with the diameter of fibers (P > 0.05). These demonstrate that the tissue-engineered tendon scaffolds made of porous polymer foam with specially designated aperture, or of polymer fiber with specially designated diameter, may serve as a good attachment substrate for THETCs.

Biopolymers↗

PubMed2001

Diverse functional activity of CD83+ monocyte-derived dendritic cells and the implications for cancer vaccines.

Antigen-loaded dendritic cells (DCs) provide key regulatory signals to T cells during a developing antitumor response. In addition to providing costimulation, mature DC provides cytokine and chemokine signals that can define the T1 vs T2 nature of the antitumor T-cell response as well as whether T cells engage in direct interactions with tumor cells. In serum-free culture conditions that hasten the differentiation of monocytes into mature DCs, certain agents, such as CD40L, accelerate phenotypic maturation (e.g., CD83 and costimulatory molecule expression) without influencing the acquisition of Dc1/Dc2 characteristics. In contrast, exposure to serum-free medium and interferon-gamma (IFN-gamma) rapidly influences CD83+ DCs to secrete high levels of IL-12, IL-6, and MIP-1beta, and promotes Dcl differentiation. In contrast, CD83+ DCs matured in serum-free medium in the absence of IFN-gamma, or in the presence of calcium signaling agents, prostaglandin-E2, or IFN-alpha, produce no IL-12, scant IL-6, and prodigious IL-8, MDC, and TARC, and promote Dc2 differentiation. T cells sensitized via IL-12-secreting, peptide-pulsed DCs secrete cytokines when subsequently exposed to relevant peptide-pulsed antigen-presenting cells (APCs) or to HLA-compatible tumor cells endogenously expressing the peptide. In contrast, T cells sensitized via IL-12 nonsecreting DC were limited to antigenic reactivation through APC contact rather than tumor cell contact. Therefore, the development of antitumor responses can be dramatically influenced not only by costimulation, but also by the cytokine and chemokine production of DCs, which must be considered in the development of cancer vaccines.

Animals↗

PubMed2001

[Studies on the chemical components from Sargassum fusiform].

Three compounds have been isolated from Sargassum fusiform collected from nanao island. Based on the spectral data and elemental analysis, they were identified as 2,4-dihydroxy-2,6-trimethyl-delta 1,alpha-cyclohexaneacetic-r-lactone, saringosterol and cedrol.

Cyclohexanes↗

PubMed2001

[Detection of proteins and mRNA of p16, p53 and nm23 in mucoepidermoid carcinoma of salivary glands and their prognostic significance].

OBJECTIVE: To disclose the relationship between the expression of p16, p53 and nm23 and the significant morphologic characteristics in mucoepidermoid carcinoma. METHODS: The proteins and mRNA in paraffin blocks from 41 mucoepidermoid carcinoma patients were studied with immunohistochemical methods and in situ hybridization respectively. RESULTS: The negative expression of p16 was found in 62.5% (15/24) of the low differentiation grade and in 29.4% (5/17) of the high differentiation grade (P = 0.037). The positive p53 expression was detected in 70.8% (17/24) of the low grade neoplasms and in 23.5% (4/17) of the high grade (P = 0.003), while positive nm23 protein was present in 37.5% (9/24) and 64.7% (11/17) respectively (P = 0.086). However, no relationship was found between positive mRNA of p16, p53, nm23 and WHO pathologic grade. CONCLUSIONS: There is a significant correlation between expression of p16 and p53 and WHO pathologic grade of mucoepidermoid carcinoma, which indicates clinical prognostic significance. No correlation is noticed between the pathologic grade and the expression of nm23 protein and mRNAs of p16, p53 and nm23.

Adult↗

PubMed2001

[Study on apoptosis of fibroblasts from abnormal scars in media containing low level of serum and interleukin 1 beta].

OBJECTIVE: To investigate the effects of low serum and interleukin 1 beta on inducing apoptosis of fibroblasts from abnormal scars and normal skins. METHODS: 6 samples from keloid, hypertrophic scar and normal skin were collected respectively. Apoptosis of different fibroblasts in media containing low level of serum and interleukin 1 beta were studied by detecting Bax and Bcl-2 protein expressions and specific DNA ladder by means of cell culture, immunohistochemistry and agrose electrophoresis. RESULTS: 1. In low level of serum, hardly occurs apoptosis of fibroblasts from keloids in correspondence with no changes of the radio of Bax/Bcl-2 proteins, and apoptosis of fibroblasts from normal skins occurs in correspondence with increasing of the radio of Bax/Bcl-2 proteins, whereas, slightly occurs apoptosis of fibroblasts from hypertrophic scars in correspondence with no change of the radio of Bax/Bcl-2 proteins. 2. In media containing interleukin 1 beta apoptosis of all three kinds of fibroblasts occurs, whereas, apoptosis of fibroblasts from keloids and hypertrophic scars takes place more seriously than that from normal skins in correspondence with increasing of the Bax/Bcl-2 radio of fibroblasts from keloids, decreasing of the Bax/Bcl-2 radio of ones from normal skins and no change of the Bax/Bcl-2 radio of ones from hypertrophic scars. CONCLUSION: Characters of different fibroblasts are different.

Adolescent↗

PubMed2001

[Telomerase activity in lung cancer and adjacent peritumoral tissues determined by TRAP-SYBR green assay].

OBJECTIVE: To develop methods for the qualitative analysis of telomerase activity by TRAP-SYBR Green assay and study telomerase activity in lung cancer and adjacent peritumoral tissues, and to explore the possible association with expression of P53. METHODS: Thirty six lung cancer tissues and 36 adjacent peritumoral tissues, 8 lung benign lesion tissues and A549 lung adenoma cell line, were examined for telomerase activity by TRAP-SYBR Green assay. The 36 lung cancer tissue samples were also examined for P53 protein expression by immunohistochemical staining. RESULTS: Telomerase activity in 5 cells of A549 lung cancer cell line was detected by TRAP-SYBR Green assay. Thirty of 36 (83.3%) lung cancer specimens, seven of 36 (19.4%) adjacent peritumoral tissues, three of 8 (37.5%) lung benign lesion tissues were positive for telomerase activity. Telomerase activity of lung cancer did not correlate with pathologic type, tumor size and clinical stage. P53 was over-expressed in 24 of the 30 (80%) lung cancer samples with telomerase activity. A significant correlation was found between telomerase activity and accumulation of P53 proteins (r = 00.60, P < 0.01). CONCLUSION: TRAP-SYBR Green assay may be a sensitive, fast and convenient method for qualitative analysis of telomerase activity, which is useful in diagnosis lung neoplasms. The relationship between telomerase activity and P53 accumulation needs further study.

Fluorescent Dyes↗

PubMed2001

[Antisense RNA for urokinase receptor inhibits the invasiveness and metastasis of lung carcinoma].

OBJECTIVE: To inhibit invasion and metastasis of human lung carcinoma cell line 95D by antisense RNA for urokinase receptor (uPAR). METHODS: Antisense RNA expression plasmid for uPAR was introduced into the highly metastatic human lung carcinoma cells 95D. Modified Boyden's chamber was used to detect the invasion ability, and nude mice were used to determine metastasis. RESULTS: Two transfected clones were found to integrate the antisense expression plasmid into genomic DNA and to express antisense RNA for uPAR. Antisense RNA blocked the uPAR expression in the transfected clones. The evident reductions of the invasiveness of antisense clones were observed by comparison with control cells, 95D cells and cells transfected with pcDNA3 vector. The metastatic potential of these two antisense clones decreased significantly in comparison with the controls (P < 0.05). CONCLUSIONS: The results suggest that antisense RNA for uPAR inhibits uPAR expression and leads to a decrease of metastatic potential of 95D cells. Antisense RNA technique may have a valuable application in anti-metastatic therapy of human lung carcinoma.

Animals↗

PubMed2001

Primary studies on heroin abuse and injury induced by oxidation and lipoperoxidation.

OBJECTIVE: To further reveal serious risks of heroin abuse to human body and clarify grave injuries of oxidation, peroxidation and lipoperoxidation induced by nitric oxide and other free radicals to heroin abusers. METHODS: Determined and compared plasma levels of nitric oxide (P-NO), vitamin C (P-VC), vitamin E (P-VE), beta-carotene (P-beta-CAR), lipoperoxides (P-LPO) and erythrocyte activities of superoxide dismutase (E-SOD), catalase (E-CAT), glutathione peroxidase (E-GSH-Px) and erythrocyte level of lipoperoxides (E-LPO) in 137 cases of heroin abusers (HAs) and 100 cases of healthy volunteers (HVs), used linear regression and correlation, stepwise regression and correlation to analyze correlation among heroin-abusing-duration (HAD), daily-heroin-abusing-quantity (DHAQ) with above determination values in the HAs. RESULTS: Compared with the above average values in the HVs group, the average values of P-NO, P-LPO, E-LPO in the HAs group were significantly increased (P < 0.0001), the average values of P-VC, P-VE, P-beta-CAR, E-SOD, E-CAT and E-GSH-Px were significantly decreased (P < 0.0001); the analysis of linear regression and correlation showed that with ascending of the HAD and DHAQ in the HAs, the values of P-NO, P-LPO, E-LPO were gradually increased (P < 0.0001), the values of P-VC, P-VE, P-beta-CAR, E-SOD, E-CAT, E-GSH-Px were gradually decreased (P < 0.0001); the analysis of stepwise regression and correlation suggested that the correlation among the HAD, DHAQ with the values of P-NO, P-VC, P-VE was the closest. CONCLUSION: The balance between oxidation and antioxidation in the HAs was seriously destroyed, and the injuries induced by nitric oxide and other free radicals, oxidation, peroxidation and lipoperoxidation reactions to the body of HAs gravely exacerbated. In the abstaining from heroin dependence, therefore, it should consider that sufficient quantum antioxidants such as VC, VE and beta-CAR are dosed to the HAs so as to abate the injuries to their bodies.

Adult↗

PubMed2001

[Correlation between the biological behavior and invasion potential in three mouse melanoma cell lines].

OBJECTIVE: To study the correlation between biological behavior and invasion potential in three homologous mouse melanoma cell lines (B16, B16F10, B16BL6). METHODS: The invasion potential of melanoma cells was assayed in a Transwell cell culture chamber. Melanin content was determined by the A value (optical density) at 470 nm in spectrophotometry. Tumor cells migration within the 3-D collagen matrix was microscopically recorded with a time-lapse video recorder and computer-assisted cell tracking system. Gelatin zymography was adopted to assay the type IV collagenase secretion. A PCR-based telomeric repeat amplification protocol (TRAP) was used for assaying telomerase activity. RESULTS: B16BL6 and B16F10 cells showed higher invasion potential than B16, but the melanin content in B16F10 was very low. B16F10 and B16BL6 possessed a higher migration ability, secreting much more type IV collagenase than the B16 though without significant difference as discovered in telomerase activity of the three melanomas cell lines. CONCLUSION: Invasion capability of mouse melanoma is closely correlated to tumor cells migration ability and secretion of type IV collagenase. Melanin content and telomerase activity are not related to the invasion ability of mouse melanoma cells.

Animals↗

PubMed2001

Clinical significance of examining IL-2R in peripheral blood lymphocytes of patients with gastric cancer.

OBJECTIVE: To understand the clinical significance of membrane receptors of interleukin-2 (CD25) in peripheral blood lymphocytes (PBL) of patients with gastric cancer. METHODS: CD25 percentages in PBL from 110 patients with gastric cancer and 100 normal individuals were examined by flow cytometry. Results were analyzed clinically and pathologically. RESULTS: Mean CD25% in PBL from normal individuals and patients with gastric cancer were 17.24 +/- 5.33 and 22.47 +/- 6.82, respectively, and the difference was significant (P < 0.01). Abnormally elevated CD25% in PBL from patients with gastric cancer were correlated with tumor site, macropathology type, tumor size, differentiation degree and clinical stage. CONCLUSION: Measuring CD25% in PBL from gastric cancer patients before surgery may provide a reference for diagnosis, immune treatment and judging prognosis.

Adult↗

PubMed2001

[The achievement of industrialized healthy aquatic breeding of hippocampus and its application prospects].

The artificial industrialized aquatic breeding of Hippocampus, which is a kind of Chinese medicinal marine material, has been achieved in the artificial aquatic breeding base of Hippocampus of Guangdong Richvast Group Company since 1983. This article reported part of the achievements of the large-scale artificial aquatic breeding experiments. The prospects for the research and application of Hippocampus as health foods and drugs were also analyzed.

Animals↗

PubMed2001

[Isolation and identification of chemical constituents from Acropora pulchra].

Three compounds, N-1-(hydroxymethyl)-2-hydroxyl-(E,E)-3,7-heptadecadienal-hexadecanamide(1), batyl alcohol(2) and n-cetanol(3) were isolated from the EtOAc portion of the ethanol extract of the hard coral Acropora pulchra collected from north China sea, and their structures were determined by MS, 1HNMR, 13CNMR analysis.

Animals↗

PubMed2001

[Characteristics of nitrogen and phosphorus pollution in the middle and small creeks, suburban Shanghai].

1. The middle and small creeks in suburban Shanghai were under heavy eutropic condition, with high loadings of nitrogen, phosphorus and organic pollutants. KN, TP and CODCr of the surface water of them were several times greater than the critical values of Types V, the worst level of water. 2. Spatial variations of N and P pollution were observed, as the creeks in different places accepted different types and amounts of pollutants. Affected by domestic sewage, the creeks nearby residential areas were often heavily polluted by NH4+ and P. The creeks in agricultural fields were more easily polluted by NO3- than by NH4+ and phosphorus. The creeks nearby livestock farms often witnessed sudden soaring of NH4+ and P. 3. N and P loadings of the creeks were also affected by the seasonal evolvement of ecological environment. With the increase of temperature and biomass, NH4+ and NO3- in the surface water were largely consumed and decreased as a result; while organic N and particle P increased as the enhancement of suspending biological particles. NO2- in the surface water increased with temperature as nitrifying bacteria became active. Total P and water soluble P also showed the trend of enhancement with the intensification of biological activities, however, they were also controlled by the condition of pH and DO in the water. 4. At the height of the summer, the surface and bottom water of the creeks differed in N and P loadings. NH4+, soluble P and total reactive P in the bottom water were higher than those in the surface; while NO3- and NO2- in the surface were higher than those in the bottom. Such water-quality stratification inevitably resulted from the enhancement of phytoplankton in the surface water and intensified release of NH4+ and P from the sediments. In the autumn, as-the temperature decrease, such phenomenon declined gradually.

China↗

PubMed2001

[Study on the correlation between the expression of protein p53 at stage III nasopharyngeal carcinoma and its biological behavior, prognosis, p53 gene mutation and the expression of LMP-1].

OBJECTIVE: To investigate p53 protein expression at stage III nasopharyngeal differentiated non-keratinizing squamous carcinoma (DNKSC) and their correlation with biological behavior and prognosis;the relationship between p53 protein expression and p53 gene mutation and LMP-1 protein expression at 58 cases of stage III DNKSC. METHODS: Immunohistochemistry (Envision) was applied to detect p53 protein and LMP-1 protein expression. Non-isotopic PCR-SSCP was used to detect p53 gene mutation. RESULTS: The p53 protein expression showed general positive rates of 65.5% (38/58) in the patients with nasopharyngeal DNKSC, being significantly higher in the group surviving less than 5 years 82.1% (32/39) than in the group surviving longer than 5 years 31.6% (6/19) (P < 0.05). Besides, it was closely correlated with the local invasion to the cranial base, there was a significant difference between invasion 74.4% (29/39) and non-invasion 47.4% (9/19) (P < 0.05). The expression of LMP-1 protein rated 72.4% (42/58), exhibiting a positive correlation with the expression of p53 protein (r = 0.504). The p53 gene mutation was found in none of the cases (0/15). CONCLUSIONS: In stage III nasopharyngeal DNKSC, the expression of p53 protein is not related to p53 gene mutation, whereas it relates to the expression of LMP-1 protein. Declined expression of p53 protein is closely related to the time of survival, and the p53 protein expression is higher in the invasive carcinoma.

Carcinoma, Squamous Cell↗

PubMed2001

[A novel rat aplastic anemia model induced by 5-fluorouracil combined with busulfan].

OBJECTIVE: To develop an aplastic anemia model with hematopoietic stem cell failure in rats. METHODS: Normal Wistar rats were injected i.p. with 5-fluorouracil and 5 days later p.o. by busulfan once a week for 3 times. A 5-FU alone group and a busulfan alone group were as control. The parameters tested indices were as following: incidence and mortality of aplastic anemia rats, blood picture, bone marrow nucleated cell count, CFU-GM of bone marrow cells and histology of hematopoietic organs. RESULTS: In the 5-FU plus busulfan group, the incidence of acute aplastic anemia was 82.0% (40/49 rats), the average survival time was (30.0 +/- 6.5) days. The remained 9 rats developed chronic aplastic anemia (18.0%). The total incidence of aplastic anemia was 100%, and the mortality was 98%. The blood cells count of the aplastic anemia rats was gradually reduced to a level of half the premedications and no CFU-GM was detected, and the patho-morphological examination showed that the bone marrow was replaced by fat cells, and the lymphoid tissue of spleen, thymus and lymph-nodes were remarkably atrophied without extra-medullary hematopoiesis. The control group (5-FU treated) developed a transient hematopoiesis suppression, and recovered rapidly to normal. Three of 12 rats in the busulfan treated group developed aplastic anemia. CONCLUSION: 5-FU combined with busulfan could impair the hematopoietic stem cells and resulted in an irreversible aplastic anemia in rats, making a rat aplastic anemia model with hematopoietic stem cell failure.

Anemia, Aplastic↗

PubMed2001

[The experimental study of transfected sFlt-Ig gene on K562 leukemia cell growth in nude mice].

OBJECTIVE: To observe the influence of transfected soluble vascular endothelial growth factor (VEGF) receptor (sFlt-1) gene on K562 leukemia cell growth in vivo. METHODS: (1) The binding region of VEGF receptor (Flt-1) ligand was combined with fragment of IgH stable region to construct Flt-Ig fusion gene and insert into pcDNA3 vector. (2) By using electroporation, the pcDNA3/Flt-Ig was transfected into K562 leukemia cells, and selected by G418. Flt-Ig mRNA expression was detected by RT-PCR. (3) The transfected pcDNA3/Flt-Ig and pcDNA3-Ig K562 cells were respectively transplanted into nude mice and the tumor volume was dynamically measured. RESULTS: Five subclones of K562 cells with high expression of Flt-Ig gene have been established, one of them was transplanted into 6 nude mice. The tumor volume of experimental mice was obviously smaller than that of control mice, about one half of the control group (P < 0.05). CONCLUSION: The growth of transfected pcDNA3/Flt-Ig K562 cells was significantly inhibited. It is possible that soluble Flt-Ig protein secreted from K562/Flt-Ig cells neutralized VEGF produced from tumor cells, therefore inhibited the tumor angiogenesis.

Animals↗

PubMed2001

[Study on the genetic variations of the major neutralization antigen VP7 of group A rotavirus type G1 in China].

OBJECTIVE: To study the genetic variations of the major neutralization antigen VP7 of group A rotavirus, type G1 in China. METHODS: Twenty-three isolates derived from seven cities (Beijing, Shenyang, Xinxiang, Shanghai, Shenzhen, Guangzhou and Chongqing) during the period of 1988-1998 were analyzed for the VP7 cDNA sequences. RESULTS: An obvious homology was observed in amino acid sequences of VP7 in the 23 isolates. Compared with the standard strain Wa, the variations were found at the position of aa 41, 49, 57, 65, 68, 74, 94, 97, 147, 170, 217, 218, 268, 281 and 291, respectively, and all of these were located in the variable region(VR)3,4,5,7,8 as well as in the C-terminal of the peptide. There seemed to be no remarkable divergence among the samples collected from different cities and all of them shared the same genetic lineage with the strain Jpn-417, though there might be one or two amino acid substitutions as time passed. When detected simultaneously with ELISA using G1 serotype-specific monoclonal antibody, the location of amino acid 91 was found presumably related to the neutralization epitope in VP7 of the type G1. Variations at some position may be resulted in the change of electropherotype. CONCLUSIONS: The results indicated that the recent isolates with representative genetic and antigenic features should be used to develop effective vaccines, and the antigenic variations should be monitored periodically.

Amino Acid Sequence↗