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Biomedical subjects

R Xu

Publications and source records attributed to R Xu.

At least 109 records · Page 6Linked to original sources
PubMed2000

[Community characteristics of soil ciliated protozoan at Dapeng Peninsula].

With the qualitative and quantitative analysis, the community characteristics of soil ciliated protozoan sample from Dapeng Peninsula, Guangdong province was studied. The comunity consisted of 42 species of ciliates, including 4 new records in China. The major species were Cohnilembus vexillarius, Colpoda henneguy, Clopoda steinii, Histriculus muscorum, Gonostomum affine, Drepanomonas revolata, Leptopharynx costatus and Dileptus alpinus. Culturing the ciliated protozoan in laboratory showed that the species succession of domimant speies during the culture was from Gonostomum affine and Histriculus muscorum n the early stage to Cohnilembus vexillaria, and then to Colpoda spp. The difference of soil cliated communities between in Dapeng Peninsula and other regions was compared, and the possible factors affecting the difference were analyzed.

Animals↗
PubMed2000

[Local expression of interleukin-12 mRNA in grafted skin in rats].

OBJECTIVE: To investigate the immunological modulating effects of IL-12 in local tissue of grafted skin. METHODS: The rats grafted with intermingled (allo-auto), allo and auto skins were employed as the model. The expression of IL-12 (P35, P40) mRNA in local tissue cells of grafted skin was determined at different time points. RESULTS: There was evident difference (P < 0.05) of the expression of IL-12 (P35) mRNA between the rats in allo grafting and auto grafting groups. There existed obvious differences of the expression between all the values in every time points in rats of intermingled grafting group except for that in 14 PBD (P < 0.05). There were significant differences of the expressions between the rats in intermingled and auto grafting groups at 4, 7, 14 and 21PBDs (P < 0.05). There were marked differences of the expression of IL-12 (P40) mRNA between the rats in allo and auto grafting groups before 21 PBD (P < 0.05). When compared with that in the rats of intermingled grafting group, the expression in allo grafting group was only different at 4 PBD (P < 0.05). There were obvious differences of the expression (P < 0.05) between the rats in intermingled and auto grafting groups on 7, 14 and 21 PBDs. During the rejection process of allo and intermingled grafting, the rule of the expression of IL-12 mRNA was in accordance with clinical observation and pathomorphological dynamic detecting results. CONCLUSION: IL-12 actively played a part in inflammatory reaction and played an important role in the conversion of T helper cell to type I T helper cell (TH1) and in mediating cellular immune process. There might be immunosuppressive effects mediated by type II T helper cell (TH2) cytokines in the intermingled skin grafts.

Animals↗
PubMed2000

[The mechanisms of inhibitory effect of bufalin on human leukemia cells].

OBJECTIVE: To study the mechanism of bufalin on human leukemia cell inhibition. METHODS: HL-60 cells were treated with bufalin at different concentrations. The growth inhibition was analysed by MTT assay, cell apoptosis by light microscopy, transmission electron microscopy, flow cytometry, TUNEL labeling method and agarose gel electrophoresis. RESULTS: (1) Treatment of HL-60 cells with bufalin remarkably inhibited the cell growth, the IC(50) value of bufalin for HL-60 cells was 0.025 micromol/L. (2) Apoptosis of HL-60 cells could be efficiently induced by bufalin at concentration of 0.010 micromol/L or higher. (3) Bufalin induced apoptosis of HL-60 cells in a dose- and time-dependent manner. (4) With G(1) phase cells decreasing, S phase cells increased, and then apoptotic cells increased with a diminution of S phase cells. (5) Bufalin-induced apoptosis of HL-60 cells was inhibited by ZnCl(2), an inhibitor of endonuclease, but not by cycloheximide, an inhibitor of protein synthesis. CONCLUSION: Bufalin could efficiently induce apoptosis of HL-60 cells, especially the S phase cells.

Apoptosis↗
PubMed2000

[Distribution of IL-1 beta in periodontium of experimental osteoporosis rats during orthodontic tooth movement].

OBJECTIVE: The purpose of this research is to study the expression change of IL-1 beta induced by forces in the periodontium of osteoporosis rats. METHODS: Eighteen SD rats were randomly divided into three groups: the normal controlled, the normal orthodontically controlled and the experimental group of osteoporosis. Six weeks after ovariectomy, the first molars were moved mesially by 50 g force created from elastic-thread for one week in the force loading groups. Then the rats were killed, and the 5 microns-thick mesiodistal sections of maxillary teeth, including the roots and periodontium were made. IL-1 beta were localized immunohistochemically in periodontium, and semiquantitative analysis of cellular-staining intensity was done by microphotometry. RESULTS: The IL-1 beta of periodontal ligament cells without loading force were mildly stained in the controlled group, but the staining intensity increased significantly in the periodontium of orthodontically moved teeth, and it showed more strengthened staining in the periodontium of force-loading teeth in osteoporosis rats. CONCLUSION: The results demonstrate that periodontal ligament cells respond to mechanical force by increased production of IL-1 beta, and this can be enhanced by osteoporosis. IL-1 beta is an important cytokine in the process of orthodontically periodontal remodeling.

Animals↗
PubMed2000

[The concentration and expression of IL-5 in human nasal polyp tissue].

OBJECTIVE: To study the concentration and expression of IL-5 in nasal polyp tissues and explore its significance in the micro-environment differentiation of eosinophils accumulation and clarify the conception of nasal polyposis. METHODS: The concentration and expression of IL-5 in nasal polyp tissues of 40 patients were determined by ELISA and immunohistochemistry, and inferior turbinate mucosa from patients with nasal polyps and healthy volunteers was used as control. RESULTS: 1. IL-5 concentration in the polyp tissues was significantly higher than that in inferion turbinate mucosa(P < 0.05). There was no significant difference in inferion turbinate mucosa between the patients with nasal polyps and healthy volunteers (P > 0.05). IL-5 concentration in polyp tissues was markedly higher in patients with extensive polypoid change of nasal mucosa, history of previous polypectomy and allergic rhinitis compared with those without these features (P < 0.05). IL-5 concentration had no correlation with age and sex (P > 0.05). 2. 80.1% of the eosinophils were positive for IL-5 and 90.9% of IL-5 positive cells were eosinophils. Only 3.7% of the lymphocytes and neutrophils were IL-5 positive, and IL-5 was not detectable in epithelial cells. IL-5 expression in eosinophils of polyp tissues was remarkably stronger than that of the turbinate mucosa (P < 0.05). There was no significant difference in inferion turbinate mucosa between the patients with nasal polyps and healthy volunteers (P > 0.05). IL-5 expression of eosinophils in polyp tissues was significantly stronger in patients with extensive polypoid change of nasal mucosa, history of previous polypectomy and allergic rhinitis compared with those without these features (P < 0.05). There was no significant difference in IL-5 expression in lymphocytes and neutrophils between polyp tissues and inferior turbinate nasal mucosa (both P > 0.05). CONCLUSION: IL-5 is a key protein in eosinophilic pathologic mechanisms in nasal polyp tissues.

Adult↗
PubMed2000

[Diagnosis and nasal endoscopic surgery of rhinogenic optic function damage].

OBJECTIVE: To explore the diagnosis and the surgical treatment of rhinogenic optic function damage through transnasal endoscopic approach. METHODS: The clinical characteristics and the results of transnasal endoscopic surgery of 32 cases(32 eyes) with rhinogenic optic function damage were analyzed. RESULTS: Eleven eyes were cured, 20 eyes were improved, 1 eye failed, No recurrence was found within 6 months to 3 years after operation. CONCLUSION: The sinus inflammatory disease might injure optic function. Early diagnosis as is important and the endoscopic sinus surgery combined with appropriate medical drug administration are in effective.

Adolescent↗
PubMed2000

[A reappraisal of hyperbaric oxygenation effect and study on serum malondialdehyde and superoxide dismutase in patients with sudden deafness].

OBJECTIVE: To reappraise the effect of HBO and to observe the changes of malondialdehyde (MDA) and superoxide dismutase (SOD) in serum of the patients with sudden deafness. METHODS: 60 patients were randomly divided into two groups. One was treated with HBO combined with medical treatment (treatment group). The other was only treated with HBO (control group). There were 30 healthy volunteers as health group. RESULTS: After treatment, there was a significant difference (chi 2 = 6.48, P < 0.05) in patient's groups in hearing examination. After treatment, SOD volume in treatment group had significant difference with health group and control group (t = 23.27, P < 0.01; t = 27.17, P < 0.01) respectively. There was a significant difference of SOD volume in treatment group itself before and after treatment course (t = 29.27, P < 0.01). There was no significant difference of SOD volume in control group itself before and after treatment(t = 1.33, P > 0.05). MDA: There was a significant difference between treatment group and control one after the treatment. There was a significant difference (t = 7.28, P < 0.01) in treatment group before and after treatment course. There was not a significant difference (t = 1.24, P > 0.05) between treatment and health group after the treatment course. There was a significant difference (t = 7.09, P < 0.01) between control group and health one after the treatment course. CONCLUSION: There was no satisfied curative effect on sudden deafness with HBO only.

Adult↗
PubMed2000

[The experience with endoscopic natural ostiotomy].

OBJECTIVE: To improve the operative technique of endoscopic middle metal antrostomy. METHODS: One hundred and thirty-five patients with chronic sinusitis were divided into two groups(first stage and second stage groups). All of them had been followed up for more than 6 months. RESULTS: Middle metal antrostomy was performed for 79 patients (158 sides) in the first group. The diameter of middle meatal window ranged from 1.0 cm (anterior-posterior diameter) to 1.5 cm(superior-inferior diameter). Improved middle meatal antrostomy was performed for 56 patients (112 sides) in the second group. The anterior-posterior diameter of the middle meatal window was over 1.0 cm, and superior-inferior diameter was over 1.5 cm. In the first group, the patency rate in the first stage was 78.48% (124/158), and satisfactory patency rate was 43.0% (68/158). The patency rate was 85.4% (135/158), and satisfactory patency rate was 45.0%(71/158). In the second group, the patency rate was 92.9%(104/112) in the first stage, and 94.6%(106/112) in the second stage. The satisfactory patency rate in both stages was 79.5%(89/112). There was significant difference between two groups(P < 0.05). CONCLUSION: The patency rate and satisfactory patency rate of middle meatal antrostomy are increased by improved technique.

Adolescent↗
PubMed1999

Molecular cloning and mapping of a novel ADAM gene (ADAM29) to human chromosome 4.

Members of the ADAM family (type I integral membrane protein with a disintegrin and metalloprotease domain) have been implicated in many important biological processes involving cell-cell and cell-matrix interactions, such as fertilization and myoblast fusion. We report here the cDNA sequence of a novel human ADAM gene (ADAM29) that contains a putative fusion peptide. Northern blot analysis revealed that the mRNA of ADAM29 is highly expressed in the testis. By radiation hybrid panel mapping, the ADAM29 gene was assigned to human chromosome 4q34.2-qter.

ADAM Proteins↗
PubMed1999

Human GHRH reduces voltage-gated K+ currents via a non-cAMP-dependent but PKC-mediated pathway in human GH adenoma cells.

1. Whole-cell voltage-gated K+ currents and the K+ current response to growth hormone-releasing hormone (GHRH) were characterised in primary cultures of human acromegalic somatotropes. 2. Both delayed rectifier (IK) and transient (IA) K+ currents were recorded from human somatotropes held at -80 mV and bathed in a solution containing Cd2+ (1 mM), TTX (1 microM) and a low concentration of Ca2+ (0.5 mM). Only IK was recorded, however, when a holding potential of -40 mV was used. 3. GHRH (10 nM) immediately and significantly reduced the amplitude of both IA and IK. While the reduction in the amplitude of IA was fully reversed following the removal of GHRH, the amplitude of IK had only partially recovered 10 min after GHRH removal. In addition, GHRH shifted the voltage-dependent inactivation curve of IA by 13.5 mV in the negative direction. 4. In a low Ca2+ and Cd2+-containing solution, the Ca2+-activated K+ channel blockers apamin (100 nM and 1 microM) and charybdotoxin (1 microM) did not alter K+ currents or the effect of GHRH on the recorded K+ currents. 5. The whole-cell K+ currents and their responses to GHRH were unaffected by the application of 8-bromo-cAMP (100 microM), Rp-cAMP (100 microM) or the protein kinase A (PKA) inhibitor H89 (1 microM). In addition, intracellular dialysis of the PKA inhibitory peptide PKI (10 microM) had no effect on the K+ current response to GHRH. 6. While the application of protein kinase C (PKC) inhibitors calphostin C (100 nM) or chelerythrine (1 microM) did not affect the amplitude of the K+ currents, the K+ current response to GHRH was significantly attenuated. Downregulation of PKC with phorbol 12,13-dibutyrate (PDBu, 0.5 microM for 16 h) also abolished the K+ current response to GHRH. In addition, intracellular dialysis of somatotropes with the PKC inhibitory peptide PKC19-36 (1 microM) prevented the GHRH-induced decrease in the amplitude of the voltage-gated K+ currents. Local application of PDBu (1 microM) significantly reduced the amplitude of the voltage-gated K+ currents in a similar manner to that induced by GHRH, but without clear recovery upon removal. 7. This study demonstrates that GHRH decreases voltage-gated K+ currents via a PKC-mediated pathway in human adenoma somatotropes, rather than by the cAMP-PKA pathway that is usually implicated in the actions of GHRH.

Adenoma↗
PubMed1999

The anatomic relation of lateral mass screws to the spinal nerves. A comparison of the Magerl, Anderson, and An techniques.

STUDY DESIGN: Analysis of the anatomic relation of the Magerl, Anderson, and An screws to the spinal nerve. OBJECTIVES: To compare the potential incidence of nerve root (ventral and dorsal ramus) injury caused by the Magerl, Anderson, and An techniques. SUMMARY OF BACKGROUND DATA: Posterior plating with lateral mass screw fixation is a common procedure for managing an unstable cervical spine. Comparative study of the Roy-Camille and Magerl techniques has been reported. However, the risk of nerve root injury for the Anderson and An techniques is not known. METHODS: Three lateral mass screw insertion techniques were performed in this study: Magerl, Anderson, and An. Each technique involved two specimens and 20 screws inserted from C3 through C7. A 20-mm-long screw was used to overpenetrate the ventral cortex. The anterolateral aspect of the cervical spine was carefully dissected to allow observation of the screw-ramus relationship. RESULTS: The overall percentage of nerve violation was significantly higher with the Magerl (95%) and Anderson (90%) techniques than with the An (60%) technique (P < 0.05). The largest percentages of nerve violation for the Magerl, Anderson, and An screws were found at the dorsal ramus (50%), the bifurcation of the ventral dorsal ramus (45%), and the ventral ramus (55%), respectively. CONCLUSIONS: The results of this study indicate that the potential risk of nerve root violation is higher with the Magerl and Anderson techniques than with the An technique.

Aged↗
PubMed1999

Direct determination of changes of interdomain orientation on ligation: use of the orientational dependence of 15N NMR relaxation in Abl SH(32).

The relative orientation and motions of domains within many proteins are key to the control of multivalent recognition, or the assembly of protein-based cellular machines. Current methods of structure determination have limited applicability to macromolecular assemblies, characterized by weak interactions between the constituents. Crystal structures of such complexes might be biased by packing forces comparable to the interdomain interactions, while the precision and accuracy of the conventional NMR structural approaches are necessarily limited by the restricted number of NOE contacts and by interdomain flexibility rendering the available NOE information uninterpretable. NMR relaxation studies are capable of providing "long-range" structural information on macromolecules in their native milieu. Here we determine directly the change in domain orientation between unligated and dual ligated subdomains of the SH(32) segment of Abelson kinase in solution, using the orientational dependence of nuclear spin relaxation. These results demonstrate that the change in domain orientation between unligated and ligated forms can be measured directly in solution.

Amides↗
PubMed1999

Cutting edge: extracellular signal-regulated kinase activates syk: a new potential feedback regulation of Fc epsilon receptor signaling.

The protein tyrosine kinase Syk is an essential element in several cascades coupling Ag receptors to cell responses. Syk and the mitogen-activated protein kinase extracellular signal-regulated kinase 1 (ERK1) were found to form a tight complex in both resting and Ag-stimulated rat mucosal-type mast cells (rat basophilic leukemia 2H3 cell line RBL-2H3). A direct serine phosphorylation and activation of Syk by ERK was observed in in vitro experiments. Moreover the mitogen-activated protein kinase/extracellular signal-regulated protein kinase (ERK) kinase (MEK) inhibitors markedly decreased the Ag-induced phosphorylation of the tyrosyl residues of Syk and its activation as well as suppressed the degranulation of the cells. These results suggest a positive feedback regulation of Syk by ERK in the cascade coupling the type 1 Fc epsilon receptor to the secretory response of mast cells; hence, the existence of a novel type of cross-talk between protein serine/threonine kinases and protein tyrosine kinases is suggested.

Animals↗
PubMed1999

Are anatomic landmarks reliable in determination of fusion level in posterolateral lumbar fusion?

STUDY DESIGN: Determination of the fusion level by direct observation and palpation of anatomic landmarks is compared with the finding obtained from a lateral intraoperative radiograph. OBJECTIVES: To assess the reliability of the use of intraoperative anatomic landmarks in determination of the fusion level. SUMMARY OF BACKGROUND DATA: Accurate determination of the level to be fused in noninstrumented posterolateral fusion is crucial. No studies are available in which the value of direct observation and palpation of the anatomic landmarks in determination of the fusion level has been assessed. METHODS: Eighty patients who underwent posterolateral fusion without instrumentation in the lumbosacral spine were included in this study. During surgery, first, the cephalad transverse process at the desired level to be fused was determined by direct observation and palpation of the anatomic landmarks; second, a metal mark was placed beneath the cephalad transverse process at the level determined by anatomic landmarks. This was followed by a lateral radiograph. The consistency and discrepancy between the use of the anatomic landmarks and lateral radiography in determining the desired fusion level were recorded. RESULTS: The fusion level determined by direct observation and palpation of the anatomic landmarks was accurate in 76 (95%) cases. In the remaining four cases, intraoperative x-rays determined that the selection of the cephalad transverse process for fusion was one level too high in three cases and one level too low in the other case. All errors in determination of the level to be fused occurred in patients who had extensive laminectomy at L4-S1. CONCLUSIONS: Determination of fusion level by direct observation and palpation of the anatomic landmarks is not reliable in patients who have had or require decompressive procedures. A lateral radiograph should be routinely obtained for accurate identification of the level to be fused.

Adult↗
PubMed1999

Flexibility of interdomain contacts revealed by topological isomers of bivalent consolidated ligands to the dual Src homology domain SH(32) of abelson.

Src homology (SH)2 and SH3 domains are found in a variety of proteins involved in the control of cellular signaling and architecture. The possible interrelationships between domains are not easily investigated, even though several cases of multiple domain-containing constructs have been studied structurally. As a complement to direct structural methods, we have developed consolidated ligands and tested their binding to the Abl SH(32) complex. Consolidated ligands combine in the same molecule peptide sequences recognized by SH2 and SH3 domains, i.e., Pro-Val-pTyr-Glu-Asn-Val and Pro-Pro-Ala-Tyr-Pro-Pro-Pro-Pro-Val-Pro, respectively; these are joined by oligoglycyl linkers. Four types of ligands were chemically synthesized, representing all the possible relative orientations of ligands. Their affinities were found to vary with binding portion topologies and linker lengths. Two of these types were shown to bind to both SH2 and SH3 dual domains with high affinities and specificities, showing increases of one order of magnitude, as compared to the most strongly bound monovalent equivalent. These results suggest that the relative orientation of SH2 and SH3 in Abl SH(32) is not fixed, and this synthetic approach may be generally useful for determining the structures of ligated complexes and for developing reagents with high affinities and specificities.

Amino Acid Sequence↗
PubMed1999

Mass spectrometric analysis of catechol-histidine adducts from insect cuticle.

Adducts of catechols and histidine, which are produced by reactions of 1,2-quinones and p-quinone methides with histidyl residues in proteins incorporated into the insect exoskeleton, were characterized using electrospray ionization mass spectrometry (ESMS), tandem electrospray mass spectrometry (ESMS-MS, collision-induced dissociation), and ion trap mass spectrometry (ITMS). Compounds examined included adducts obtained from acid hydrolysates of Manduca sexta (tobacco hornworm) pupal cuticle exuviae and products obtained from model reactions under defined conditions. The ESMS and ITMS spectra of 6-(N-3')-histidyldopamine [6-(N-3')-His-DA, pi isomer] isolated from M. sexta cuticle were dominated by a [M + H]+ ion at m/z 308, rather than the expected m/z 307. High-resolution fast atom bombardment MS yielded an empirical formula of C14H18N3O5, which was consistent with this compound being 6-(N-1')-histidyl-2-(3, 4-dihydroxyphenyl)ethanol [6-(N-1')-His-DOPET] instead of a DA adduct. Similar results were obtained when histidyl-catechol compounds linked at C-7 of the catechol were examined; the (N-1') isomer was confirmed as a DA adduct, and the (N-3') isomer identified as an (N-1')-DOPET derivative. Direct MS analysis of unfractionated cuticle hydrolysate revealed intense parent and product ions characteristic of 6- and 7-linked adducts of histidine and DOPET. Mass spectrometric analysis of model adducts synthesized by electrochemical oxidative coupling of N-acetyldopamine (NADA) quinone and N-acetylhistidine (NAcH) identified the point of attachment in the two isomers. A prominent product ion corresponding to loss of CO2 from [M + H]+ of 2-NAcH-NADA confirmed this as being the (N-3') isomer. Loss of (H2O + CO) from 6-NAcH-NADA suggested that this adduct was the (N-1') isomer. The results support the hypothesis that insect cuticle sclerotization involves the formation of C-N cross-links between histidine residues in cuticular proteins, and both ring and side-chain carbons of three catechols: NADA, N-beta-alanyldopamine, and DOPET.

Animals↗
PubMed1999

Anatomic relation between the cervical pedicle and the adjacent neural structures.

STUDY DESIGN: An evaluation of the anatomic relation between the cervical pedicles and the adjacent neural structures. OBJECTIVES: To determine quantitatively the antomic relation of the cervical pedicles to the adjacent nerve roots and dural sac. SUMMARY OF BACKGROUND DATA: Transpedicular screw fixation in the cervical spine has been reported, but little quantitative data regarding the anatomic relation between the cervical pedicles and the surrounding neural structures are known. METHODS: Twenty cadavers were used for dissection to observe the relations of the cervical pedicles to the adjacent dural sac and nerve roots. After removal of whole posterior bony elements including the spinous processes, laminas, and lateral masses, the isthmus of the pedicles, the dural sac, and the nerve roots of C3-C7 were exposed. Direct measurements included the distance from the pedicle to the superior and inferior nerve roots and the dura. Also, the pedicle height and width were measured at its isthmus. RESULTS: No distance was found between the pedicle and the superior nerve root, nor between the pedicle and the dural sac at C3-C7 for all specimens. The mean distances between the pedicle and the inferior nerve roots for all specimens ranged from 1.4 to 1.6 mm. The mean pedicle heights and widths for all specimens at C3-C7 ranged from 6.0 to 6.5 mm and 4.7 to 5.3 mm, respectively. A significant difference between male and female specimens was noted in the pedicle heights for all levels measured (P = 0.001), and in the pedicle widths for the levels of C4 and C6 (P = 0.05). CONCLUSIONS: This study suggests that the incidence of neurologic injuries may be higher in screw penetration of the medial or superior cortex of the pedicle than in screw penetration of the inferior cortex of the pedicle.

Aged↗