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Biomedical subjects

M Xiao

Publications and source records attributed to M Xiao.

At least 55 records · Page 3Linked to original sources
PubMed1999

cDNA cloning and sequencing of MH2 domain of Smad2 from human dental pulp cells.

OBJECTIVE: The purpose of this study was to clone and sequence the cDNA of MH2 domain of Smad2 from human dental pulp cells. METHODS: In this study, total RNA was isolated from primary cultured human dental pulp cells and reverse-transcribed into cDNA. The desired DNA product was obtained by nested PCR with 4 smad2 MH2 domain-specific primers. The segment was inserted into pBluescript II SK vector and the resulting plasmid was transformed into E. coli JM109. The double-strand cDNA of positive clone was sequenced by PE317-A automatic sequencing. RESULTS: cDNA of MH2 domain of Smad2 was obtained from human dental pulp cells. The sequence was consistent with that cloned from a human kidney cDNA library. No mutation was found. CONCLUSION: This study provides the first evidence of expression of smad2 in human dental pulp cells, and indicates that TGF-beta signaling may be mediated by Smad2 in human dental pulp cells. The cDNA cloned in pBluescript/S2MH2 could be used for further functional studies of Smad2 and MH2 domain in dental pulp cells.

Base Sequence↗
PubMed1999

[Extract of cemental matrix enhance periodontal cells bind to the root surface].

OBJECTIVE: To investigate whether the extract of cemental matrix can enhance periodontal cells binding to the root surfaces. METHODS: Healthy human gingiva and periodontal ligament were acquired from patients, then gingival fibroblasts and periodontal cells were cultured in vitro. On the other hand, extract of cemental matrix was separated and clarified from healthy teeth which were extracted because of orthodontic treatment. Finally, the effects of cementum matrix with different concentration and different time on the attachment of gingival fibroblast and periodontal cells to root surface were observed. RESULTS: The extract of cemental matrix could enhance the initial attachment of human gingival fibroblasts (HGF) and human periodontal cells (HPC) to the surface of root, and such effects were strengthened with increasing density and time. The optimal concentration of extract of cell attachment 10 micrograms/ml, and the attachment was also proportional to the incubation time, reaching near maximal levels at 2 hours, furthermore, the extract of cemental matrix was more effective in promoting the attachment of human periodontal cells than that of gingival fibroblasts. CONCLUSION: The extract of cemental matrix can enhance the initial attachment of HGF and HPC on the root surface.

Cell Adhesion↗
PubMed1999

[To evaluate the examinations both colour Doppler flow image and CT for orbital pseudotumors].

PURPOSE: To explore the values of colour doppler flow image(CDFI) technique and computer tomographic(CT) scan in diagnosising orbital pseudotumors. METHODS: CDFI and CT were used for examining 67 cases of orbital pseudotumors demonstrated with surgery and pathaology. The results were treated with self-match design Chi-square test. RESULTS: The diagnosis validities for 29 mass-type cases with CDFI and CT were 44.8% and 82.8%, respectively, with significant difference (chi 2 = 5.88, P < 0.05). The validities for 25 diffuse-type cases were 84.0% and 56.0%, respectively, with significant difference. (chi 2 = 4.0, P < 0.05). The validities for 19 mixture-type cases were 63.2% and 78.9%, respectively, with no significant difference (chi 2 = 1.63, P > 0.05). The diagnosis validities for all 67 cases were 63.0% and 72.7%, respectively, with no significant difference (chi 2 = 1.16, P > 0.05). CONCLUSION: The diagnosis validities with both imaging methods were not different for diagnosis of orbital pseudotumors. But the values for diagnosing various pseudotumors were different. The validity with CDFI was superior to CT in diffuse type; CT was superior to CDFI in mass type; while the validity with CDFI and CT were not significant different in mixture type.

Adolescent↗
PubMed1998

Conformational changes between the active-site and regulatory light chain of myosin as determined by luminescence resonance energy transfer: the effect of nucleotides and actin.

Myosin is thought to generate movement of actin filaments via a conformational change between its light-chain domain and its catalytic domain that is driven by the binding of nucleotides and actin. To monitor this change, we have measured distances between a gizzard regulatory light chain (Cys 108) and the active site (near or at Trp 130) of skeletal myosin subfragment 1 (S1) by using luminescence resonance energy transfer and a photoaffinity ATP-lanthanide analog. The technique allows relatively long distances to be measured, and the label enables site-specific attachment at the active-site with only modest affect on myosin's enzymology. The distance between these sites is 66.8 +/- 2.3 A when the nucleotide is ADP and is unchanged on binding to actin. The distance decreases slightly with ADP-BeF3, (-1.6 +/- 0.3 A) and more significantly with ADP-AlF4 (-4.6 +/- 0.2 A). During steady-state hydrolysis of ATP, the distance is temperature-dependent, becoming shorter as temperature increases and the complex with ADP.Pi is favored over that with ATP. We conclude that the distance between the active site and the light chain varies as Acto-S1-ADP approximately S1-ADP > S1-ADP-BeF3 > S1-ADP-AlF4 approximately S1-ADP-Pi and that S1-ATP > S1-ADP-Pi. The changes in distance are consistent with a substantial rotation of the light-chain binding domain of skeletal S1 between the prepowerstroke state, simulated by S1-ADP-AlF4, and the post-powerstroke state, simulated by acto-S1-ADP.

Actins↗
PubMed1998

[Study on the replacement of the portal vein of pig with autogeneous-peritoneal tube].

OBJECTIVE: To investigate the possibility of applying autogeneous peritoneal tube in the portal vein reconstruction. METHODS: Twenty-seven small healthy domestic pigs were used. A section of portal vein about 2.5-3.0 cm long was resected and replaced by autogenous peritoneum tube (APT), autogenous vein and decron artificial blood vessel respectively. Patency and pathological changes of the APT grafts were investigated after the replacement. RESULTS: Twenty-four animals survived the operation. In the early stage of replacement, the APTs were dilated slightly, the cannual patency rate (CPR) was 12/13(92.3%). 3 months later, the fibrous hypertrophy and thickness were observed. The CPR was 8/10(80%). 2 more months later, the CPR was 4/6(66.7%), which was quite similar to that reconstructed by autogeneous vein. All three pigs which were replaced by decron blood vessel were dead within three to five hours after operation because of portal thrombi found by autopsy. After 12 weeks of replacement, scanning electron microscopy revealed that APT grafts were covered with a layer of endothelial-like cells. Endothelial cells and mesothelial cells were seen under transmitted electronic microscopy. CONCLUSIONS: The long-term patency of the APTs were slightly lower than that of the autogenous vein, peritoneum might be a perspective self-material for portal vein reconstruction and worth further studying.

Animals↗
PubMed1998

[Radionuclide pulmonary perfusion imaging in evaluating pulmonary hypertension in patients with congenital heart disease].

OBJECTIVE: To evaluate the degree of pulmonary hypertension in patients with congenital heart disease (CHD) by using radionuclide pulmonary perfusion imaging. METHOD: The pulmonary perfusion in 81 patients with left to right cardiac shunts was examined by scintigram with macroaggregates of (99m)Tc-labeled human serum albumin (PPS). PPS was analyzed for (1) lung regional radionuclide count (LRC), (2) right upper and lower lung count ratio (RULR), (3) kidney count ratio (KCR). The results were compared with those of cardiac catheterization exam. RESULT: There were correlation between mean pulmonary arterial pressure (mPAP), total pulmonary resistance (TPR), and PPS (KCR, RULR with mPAP gamma = 0.25, 0.35; LRC, KCR with TPR gamma = -0.34, 0.29). Five patients repeated PPS test after early operation. There were no changes in PPS. CONCLUSION: The degree of reversibility of pulmonary hypertension in patients with CHD could be quantitatively analysed by PPS.

Adolescent↗
PubMed1998

[Dental welding titanium and its clinical usage].

Due to its excellent biocompatibility, desirable chemical and mechanical properties, Titanium has been used for implant denture, RPD and FPD, where welding techniques were indispensable. This paper introduces 5 useful modern ways to weld Titanium and their clinical usage. They are: laser, plasma welding, TIG, infraned brazing and Hruska electrowelding.

Dental Soldering↗
PubMed1998

Effects of retinal laser photocoagulation on photoreceptor basic fibroblast growth factor and survival.

PURPOSE: In an unpublished study, the authors found that immunoreactivity for basic fibroblast growth factor (bFGF) is increased in rod photoreceptors adjacent to long-standing laser burns in human diabetic retinas. The goal of this study was to determine whether laser photocoagulation produces a similar increase in photoreceptor bFGF and promotes survival of these cells in dystrophic rodent retinas. METHODS: Threshold (whitening) and subthreshold (nonwhitening) laser burns were made in retinas of normal and Royal College of Surgeons (RCS) rats and normal and rds mice. The retinas were processed for immunocytochemical and morphometric analyses. RESULTS: In nonlasered normal rat and mouse retinas, bFGF immunoreactivity was prominent in the nuclei of Müller cells and astrocytes. Photoreceptors were bFGF negative except for a zone of bFGF-immunoreactive rods near the ora serrata. Some photoreceptors in nonlasered retinas of RCS rats and rds mice became bFGF immunoreactive. After laser treatment, bFGF immunoreactivity was markedly increased in all photoreceptors flanking the threshold burns and within the subthreshold burns in normal and mutant rats and mice. In RCS rat retinas, photoreceptor bFGF immunoreactivity remained elevated within subthreshold burns and flanking the threshold burns, and photoreceptor survival was prolonged. In rds mouse retinas, increased bFGF immunoreactivity in photoreceptors was not sustained and their degeneration was not retarded. CONCLUSIONS: Laser treatment of RCS rat retinas produced a sustained increase in bFGF immunoreactivity in photoreceptors and prolonged their survival, but laser treatment of rds mouse retinas did not have a long-term effect on photoreceptor bFGF immunoreactivity or survival. Although species differences in laser effects on photoreceptor bFGF and survival are apparent, the finding that rods flanking laser burns in human retinas have sustained increases in bFGF immunoreactivity suggests that laser treatment may be useful for prolonging survival of mutant photoreceptors in retinas of patients with retinitis pigmentosa.

Adult↗
PubMed1997

Flt3 ligand enhances the yield of primitive cells after Ex vivo cultivation of CD34+ CD38dim cells and CD34+ CD38dim CD33dim HLA-DR+ cells.

Flt3 ligand (FL) has been proposed as a possible modulator of early hematopoietic cell growth. The purpose of this study was to analyze the impact of FL on ex vivo expansion of hematopoietic cells obtained from adult donors. We sought to precisely identify hematopoietic populations responsive to FL and to quantitate the ability of FL to enhance the survival and/or proliferation of early hematopoietic precursors in a stroma-free culture system. Towards that end, four CD34+ subsets were isolated and their response to FL was characterized. In methylcellulose, FL significantly increased colony formation by CD34+ CD38dim cells but not CD34+ CD38+ cells. In suspension culture, the enhancement of cell expansion by FL was 10 times greater with the CD34+ CD38dim fraction than the CD34+ CD38+ fraction. FL stimulated the generation of colony-forming unit-granulocyte-macrophage (CFU-GM) from the CD34+CD38dim fraction by 14.5- +/- 5.6-fold. To determine if CD34+ CD38dim cells responded uniformly to FL, the population was subdivided into a CD34+ CD38dim CD33dim HLA-DR+ (HLA-DR+) fraction and a CD34+ CD38dim CD33(dim) HLA-DRdim (HLA-DRdim) fraction. FL was far more effective at stimulating cell and progenitor growth from the HLA-DR+ fraction. To determine if FL enhanced or depleted the number of precommitted cells in expansion culture, CD34+ CD38dim and HLA-DR+ fractions were incubated in liquid culture and analyzed by flow cytometry. Inclusion of FL enhanced the absolute number of primitive CD34+ CD33dim cells and CD34+ HLA-DRdim cells after 5 to 12 days of cultivation. To confirm immunophenotypic data, the effect of FL on long-term culture-initiating cells (LTCIC) was determined. After 2 weeks of incubation of CD34+ CD38dim or HLA-DR+ cultures, LTCIC recoveries were significantly higher with FL in 5 of 6 trials (P < . 05). For HLA-DR+ cells, LTCIC recoveries averaged 214% +/- 87% of input with FL and 24% +/- 16% without FL. In contrast, HLA-DRdim LTCIC could not be maintained in stroma-free culture. We conclude that less than 10% of CD34+ cells respond vigorously to FL and that those cells are contained within the HLA-DR+ fraction. FL stimulates the expansion of total cells, CD34+ cells, and CFU-GM and enhances the pool of early CD34+ CD33(dim) cells, CD34+ HLA-DRdim cells, and LTCIC. These data indicate that it is possible to expand hematopoietic progenitors from adult donors without losing precursors from the precommitted cell pool.

ADP-ribosyl Cyclase↗
PubMed1997

Orientation of cross-bridges in skeletal muscle measured with a hydrophobic probe.

Cis-parinaric acid (PA) binds to a hydrophobic pocket formed between the heavy chain of myosin subfragment-1 (S1) and the 41-residue N-terminal of essential light chain 1 (A1). The binding is strong (Ka = 5.6 x 10(7) M-1) and rigid (polarization = 0.334). PA does not bind to myofibrils in which A1 has been extracted or replaced with alkali light chain 2 (A2). As in the case of S1 labeled with other probes, polarization of fluorescence of S1-PA added to myofibrils depended on fractional saturation of actin filament with S1, i.e., on whether the filaments were fully or partially saturated with myosin heads. Because fluorescence quantum yield of PA is enhanced manyfold upon binding, and because PA binds weakly to myofibrillar structures other then A1, the dye is a convenient probe of cross-bridge orientation in native muscle fibers. The polarization of a fiber irrigated with PA was equal to the polarization of S1-PA added to fibers at nonsaturating concentration. Cross-linking of S1 added to fibers at nonsaturating concentration showed that each S1 bound to two actin monomers of a thin filament. These results suggest that in rigor rabbit psoas muscle fiber each myosin cross-bridge binds to two actins.

Animals↗
PubMed1997

Mineralized nodule formation by human dental papilla cells in culture.

Human dental papilla cells were enzymatically separated from deciduous tooth germs of an 8-month-old embryo legally aborted. The second passage cells were cultured up to 35 days in 3 groups. The beta-GP group was cultured in the Dulbecco MEM containing ascorbic acid and beta-glycerophosphate supplemented with 15% fetal bovine serum. The Dex group was in the same medium, in addition containing dexamethasone. The control group contained none of the 3 chemicals. Mineralized nodules were formed after 15 days in the beta-GP and Dex groups. Only in the presence of ascorbic acid and organic phosphate did they mineralize. The addition of dexamethasone caused a significant increase in the number of nodules. By electron microscopy, the nodules contained needle-shaped crystals associated with a network of collagen fibrils. Calcium and phosphorus were detected by energy-dispersive X-ray microanalysis in the nodules. Furthermore, the crystalline material exhibited a pattern consistent with hydroxyapatite and dentin when examined by X-ray diffractometry. Cells showed high levels of alkaline phosphatase activity, which was increased 2-3 times in the presence of the 3 chemicals. These results indicated that human dental papilla cells have the ability to form dentin in culture. The formation of mineralized nodules by human dental papilla in vitro provides a useful model for studying the morphogenesis and differentiation of dental papilla ectomesenchyme.

Alkaline Phosphatase↗
PubMed1997

[A self-designed crooked suturing needle anastomosis in the treatment of posterior urethral strictures or occlusions].

A self-designed crooked suturing needle was described and has been used in the surgical treatment of complicated posttraumatic posterior urethra strictures or occlusions in 27 cases from Mar. 1986 to Feb. 1996. 1-stage transperineal end to end anastomosis of the bulbomenbranous urethra to the prostatic urethra with indeed healthy mucosa to healthy mucosa after scar tissue had been excised was performed with the above mentioned crooked suturing needle. 27 patients were followed up for 3 months to 9.5 years after operation with a satisfactory result of 100% and all voided freely with no sound urethral dilation and no trouble after the removal of the catheter. The erect dysfunction of 5 of the patients after the operation within 1-5 years restored completely.

Adolescent↗
PubMed1997

[Simultaneous coronary artery bypass grafting with other cardiovascular surgical procedures].

To improve the effect and reduce the mortality of the simultaneous coronary artery bypass grafting (CABG) with other cardiovascular surgical procedures, from Nov, 1984 to July, 1996, 51 patients underwent such operation. Among them 45 patients had valvular heart diseases, 4 postinfarction ventricular septal defect and ventricular aneurysm, and 1 myxoma of left atrium and abdominal aortal aneurysm. The operative mortality was 5.85% (3/51), and 3 patients died. Cardiovascular surgical patients of over 50 years or with angina pectorsi and ECG confirmed myocardiac ischemia should undergo coronary angiography routinely. If main coronary artery branches stenosis occupied over 50%, CABG must be performed. During the operation revasculariztion should be made as full as possible to enhance myocardiac protection and reduce the ascending aortic cross-clamping time.

Adolescent↗
PubMed1997

[Effect of complete dentures on the blood flow and blood cell velocity of alveolar mucosal microcirculation].

The Purpose of this study was to determine the effects of complete dentures on alveolar mucosa microcirculation. The alveolar mucosal microcirculation of 17 edentulous subjects was measured by videomicroscope. The variance of the alveolar mucosa microcirculation before and after insertion of the dentures was compared. The results showed that: 7 days after wearing complete dentures, the mucosal blood flow and blood cell velocity of maxillary anterior alveolar ridge crest decreased significantly (P < 0.05), those of labial region of maxillary anterior alveolar ridge increased significantly (P < 0.05), 14 days after wearing complete dentures, the mucosal blood flow and blood cell velocity almost recovered the levels before wearing the dentures. The results can be relative to adjustment the occlusion in the early period of wearing the complete dentures and not wearing the complete dentures at night.

Adult↗
PubMed1997

[The modified RPI clasp design].

The modified RPI clasp was described and compared with the conventional RPI clasp in the article. The modified RPI clasp could provide adequate retention with the minimum undercut of the most distal part of abutment tooth and gain good esthetical effect. The I bar tip would disengage from the tooth and reduce or avoid torsional forces transmitted to the abutment tooth when rotation of distal-extension base occurred around the mesio-occlusal rest. Therefore, it is a new type of clasp design for the distal-extension removable partial dentures.

Dental Clasps↗
PubMed1996

Binding of S1(A1) and S1(A2) to F-actin.

The binding curve of myosin subfragment-1 (S1) to F-actin is not a simple hyperbola: at high concentrations of S1 the binding curve can be transformed into a linear plot ("normal" binding), but at small concentrations of S1 the binding complications deform the binding curve and produce nonlinear transforms ("anomalous" binding) [Andreev, O. A., & Borejdo, J. (1992) J. Muscle Res. Cell Motil. 13, 523-533]. This anomalous behavior may result either from the heterogeneity of S1 in regard to light chain isoforms or from the cooperativity between S1's. To distinguish between these possibilities we measured the affinity and the orientation of S1(A1) and S1(A2) with respect to F-actin. Affinity was measured in vitro by ultracentrifugation in the presence of F-actin, and orientation was measured in vivo by a combination of polarization of fluorescence and linear dichroism. We found that both the affinity and the orientation depended on the relative concentration of S1 isomer and actin: when S1 was in excess or was equimolar with actin (filament saturated with S1), each isomer bound F-actin with an affinity of 2 x 10(6) M-1 and was oriented approximately perpendicularly to the muscle axis. When actin was in excess (filament unsaturated with S1), each isomer bound F-actin with an affinity of 1.2 x 10(7) M-1 and was oriented more parallel to the muscle axis. S1(A1) and S1(A2) labeled on the light chain had different polarizations when bound to unsaturated filaments but had the same polarizations when bound to saturated filaments. These results excluded heterogeneity as a reason for anomalous binding and suggested that binding occurred with negative cooperativity. We think that the negative cooperativity occurs when saturation of actin filaments with heads leads to the lack of vacant adjacent sites on a filament and a consequent prevention of S1 binding to two actin protomers.

Actins↗