Search PubMed⌕ Search

Biomedical subjects

H Xie

Publications and source records attributed to H Xie.

At least 73 records · Page 4Linked to original sources
PubMed2001

[Stress-strain properties of the tissue-engineered cartilage].

This study was conducted to investigate the biomechanical properties of tissue-engineering cartilage. The compressive modulus of the collagen-chondrocyte constructs that had been cultured in vivo for 16 weeks and the centrifuge-tube-cultured cartilage in vitro were measured with 5% strain. The results showed that the compressive moduli of the centrifuge-tube-cultured cartilage at the 4th, 8th, 12th and 16th weeks were 0.352 MPa, 0.653 MPa, 0.233 MPa and 0.262 MPa respectively. The top modulus among them was at the 8th week. The compressive modulus of the neocartilage engineered by the collagen-chondrocyte constructs in vivo for 16 weeks was 10.668 MPa and reached the same order of magnitude as human fetal articular cartilage, but it is still under that of the human fetal articular cartilage actually. The culture methods should be developed further though the dynamic alteration of the compressive modulus of the centrifuge-tube-cultured neocartilage is in accord with that of the GAG/DNA content ratio of the neocartilage.

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

A retrospective study of continuous renal replacement therapy versus intermittent hemodialysis in severe acute renal failure.

OBJECTIVE: To investigate the efficacy of continuous renal replacement therapy (CRRT) versus intermittent hemodialysis (IHD) in patients with severe acute renal failure (ARF). METHODS: One hundred and ninety-three severe ARF patients who received renal support between December 1978 and December 1998 were involved in this study. Of them, 101 (52.3%) were treated with CRRT (CRRT group), and 92 (47.7%) with IHD (IHD group). RESULTS: Sixty (59.4%) patients in the CRRT group got through the acute phase of disease and 41 (40.6%) patients did not survive while in the IHD group 59 (64.1%) patients survived and 33 (35.9%) patients did not. No significant difference in survival rate was found between the two groups. 24 of 64 patients (37.5%) in the CRRT group with multiple organ dysfunction syndrome (MODS) survived, while in the IHD group, 8 out of 44 (27.3%) survived, their survival rate was much lower than that in the CRRT group. Patients in CRRT group were more severely ill, as manifested by lower mean arterial pressure, higher APACHE II score, more dysfunctioned organs and requiring mechanical ventilation and vasopressor support as compared with patients in the IHD group, CRRT was found to improve hemodynamic stability with a better fluid balance and control of biochemical status, increased nutritional intake and a shorter duration of acute renal failure (P < 0.05). CONCLUSION: CRRT perhaps may be the best choice in the treatment of severe ARF patients, for it can offer several distinct advantages compared to IHD. These may contribute to improving the survival rate of ARF patients, particularly those that are critically ill patients.

Acute Kidney Injury↗
PubMed2001

[Association between polymorphism of alpha 1-antichymotrypsin and apolipoprotein E gene and Parkinson's disease in Shanghai Hans].

OBJECTIVE: To explore the relationship between polymorphism of alpha 1-antichymotrypsin(AACT) and apolipoprotein E(ApoE) genes and the risk of Parkinson's disease(PD) in Shanghai Hans. METHODS: Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were used to study the distribution of AACT and ApoE gene polymorphism in 64 PD cases and 101 healthy elderly persons as controls. Association analysis was performed using odds ratio (OR) and chi 2 test. RESULTS: No difference in distribution of AACT A/T allele polymorphism was found between PD cases and healthy controls(chi 2 = 0.83 P = 0.363 > 0.05), but AACT-AA genotype was associated with PD(OR = 2.68, chi 2 = 4.31 P = 0.038 < 0.05). The ApoE gene polymorphism was not associated with PD(allele: chi 2 = 2.85 P = 0.241 > 0.05; genotype: chi 2 = 9.25 P = 0.099 > 0.05). The AACT-AT genotype frequency in PD patients was significantly lower than that in the controls without ApoE epsilon 4 allele(OR = 0.47, chi 2 = 4.10 P = 0.043 < 0.05). In AACT-AT genotype the ApoE epsilon 4 allele was associated with PD(OR = 3.26, chi 2 = 5.53 P = 0.019 < 0.05). CONCLUSION: The AACT-AA genotype and AACT-AT genotype with ApoE epsilon 4 might be susceptible factors for PD in Shanghai Hans.

Adult↗
PubMed2001

[The effects of dialysate and ultrafiltration flow rate on solute clearance during continuous renal replacement therapy].

OBJECTIVE: To study the solute clearance during various forms of continuous renal replacement therapy(CRRT) and test the formulas that allow the prediction of the influence of dialysate and ultrafiltration flow rate on small solute removal during CRRT. METHOD: Five patients with acute renal failure were included in the study and were treated by venovenous CRRT using the PRISMA predilution system. Solute clearance of urea nitrogen(UN), creatinine(Cr), uric acid(Ua), phosphate(P) and beta(2)-microglobulin(beta(2)-M) were evaluated during CRRT with different dialysates and ultrafiltration flow rates. RESULTS: The determined clearance of small molecular solutes during continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodialysis(CVVHD) was similar with the following formulas: K(UF) = (Q(UF)/60) x Q(B)/(Q(B) + Q(UF)/60) (in CVVH), Kd = Q(D)/60 (in CVVHD), where K is the clearance, Q(B), Q(D) and Q(UF) are blood, dialysate and ultrafiltration flow rates, respectively. There was very significant correlation between calculated values of K(UF) and observed clearances of small solutes such as UN, Cr, Ua and P during CVVH, between calculated values of Kd and observed clearances of UN, Cr, Ua but not P during CVVHD (P < 0.001). Clearances of UN, Cr, Ua and P during CVVHD were greater than those during CVVH, but clearance of beta(2)-M during CVVHD was less than that during CVVH. Interaction between convection and diffusion was found during continuous venovenous hemodiafiltration (CVVHDF). CONCLUSIONS: The previous formulas can provide with the prediction of the clearance of small molecular solutes during CVVH and CVVHD. The present results demonstrate that diffusion is more efficient in removing small solutes than convection but less efficient in removing large solutes than convection. There is interaction between convection and diffusion during CVVHDF.

Acute Kidney Injury↗
PubMed2001

[Septorhinoplasty for nasal deviation complicated with septal cartilage deformity].

OBJECTIVE: To investigate a method for safe, simple and effective correction of nasal deviation complicated with the deformity of nasal septal cartilage. METHODS: From one side of the septal cartilage, the whole muco-perichondrium was separated, and from the other side a U-shaped muco-perichondrium was separated. The bottom of the septal cartilage was freed while a part of cartilage connected with the vomer was reserved. RESULTS: 12 patients were operated on with this technique for nasal deviation from March 1996 to August 1999. The follow-up period ranged from 1 to 12 months. The overall result was successful in all cases except one of recurrence. CONCLUSION: This technique not only provides wide space for removing the spetal cartilage, but also creates a cartilaginous framework to support the septal cartilage in the middle without lowing the nasal tip, which avoids the tendency of migrating to its original position caused by external fixation. This technique also ensures replacing the septal cartilage in the midline regardless of the deformity of anterior nasal spine and the vomer.

Adult↗
PubMed2001

[Microsurgical treatment of apical region by combined orbital pterygoid approach].

OBJECTIVE: To study microsurgical treatment of orbital apical region tumor by combined orbital pterygoid approach. METHOD: In 21 cases, manifestations and surgical methods were analyzed retrospectively. The surgical approach and procedure were discussed. RESULTS: All the 21 cases were treated by combined orbital pterygoid approach. The tumors were removed completely in 18 cases, and partially resected in 3. There was no death. CONCLUSIONS: This kind of mass is difficult to explore by either transorbital or transcranial approach because of its position. Combined orbital pterygoid approach provides better access and exploration. Appropriate surgical approach, hemostasis and gentle microsurgical manipulation are the key to reducing postoperative complications.

Adolescent↗
PubMed2001

[Determination of thyroxine enantiomers in human plasma with normal high performance liquid chromatography-chiral complex exchange mobile phase].

An HPLC method was developed with normal HPLC-chiral complex mobile phase for the separation and determination of D- and L-thyroxine enantiomers (D- and L-T4) in human plasma. The method includes extraction of thyroxine from plasma and separation of thyroxine enantiomers on HPLC silica column with chiral eluent containing L-proline, cupric acetate and triethylamine (TEA). The sensitivity of the method was 0.1 mg/L. The precisions of inter-day and intra-day, linearity, extraction recovery, and stability of T4 enantiomers in plasma and in deproteinized plasma were determined for the validation of the method. Baseline enantioseparation of the compounds containing D- and L-T4 was achieved. Meantime we determined the concentrations of D-T4 and L-T4 in plasma of 15 volunteers with euthyroid, hypothyroid and hyperthyroid symptoms. Liquid chromatographic method based on the described procedure was useful for the determination of D- and L-thyroxine in patient plasma and for pharmacokinetics investigation.

Chromatography, High Pressure Liquid↗
PubMed2001

[Telomerase activity inhibition and apoptosis induction of BEL-7404 human hepatoma cells by antisense oligonucleotides to telomerase RNA component].

Telomerase activity was detected in all of four human hepatoma cells but absent in normal liver tissue. Telomerase activity of BEL-7404 human hepatoma cells was inhibited effectively by antisense oligonucleotide to telomerase RNA component at final concentration of 1 mumol/L, whereas sense and missense oligonucleotides have no effects on its activity. The inhibition of telomerase activity was weakened, as the concentration of antisense oligonucleotide decreased. Treating BEL-7404 human hepatoma cells 96 hours continuously by the antisense oligomers at final concentration of 5 mumol/L, the morphology of treated cells changed and apoptosis percent of the cells increased markedly.

Apoptosis↗
PubMed2001

[The influence of type I collagen on the cell behavior of human embryonic periosteous osteoblasts].

OBJECTIVE: To study the influence of type I collagen (COL I) on the cell behavior of human periosteous osteoblasts (OB) and the application of type I collagen in constructing bioactive artifical bone. METHODS: OB were cultured on dishes coated with bovine type I collagen in different final concentrations. The cell adhesion was examined by the methods of cell count, the proliferation of OB was studied by 3H-TdR, and the osteoblastic ability was assessed by the synthesis of collagen, osteocalcin and alkaline phosphatase (ALP). RESULTS: OB cultured on type I collagen layer had the following characteristics: 1. The amounts of adhesive cells were maximal top in 25 micrograms/ml final concentration; 2. The proliferation of OB was decreased above 12.5 micrograms/ml final concentration (P < 0.05); 3. The synthesis of type I collagen was reduced slightly (above 25 micrograms/ml, P < 0.05); 4. The secretion of osteocalcin was increased markedly (above 6.25 micrograms/ml, P < 0.05, which reached maximally in 25 micrograms/ml); 5. The ALP activity was also increased (above 12.5 micrograms/ml, P < 0.05). CONCLUSION: Type I collagen promotes the expression of osteoblastic phenotype and cell adhesion. When the scaffold materials for bone tissue engineering are coated with type I collagen, the osteogenesis of OB is enhanced to accelerate the transformation course from artificial bone to biological bone, the best final concentration is 25 micrograms/ml.

Alkaline Phosphatase↗
PubMed2000

The structural basis for the ligand specificity of family 2 carbohydrate-binding modules.

The interactions of proteins with polysaccharides play a key role in the microbial hydrolysis of cellulose and xylan, the most abundant organic molecules in the biosphere, and are thus pivotal to the recycling of photosynthetically fixed carbon. Enzymes that attack these recalcitrant polymers have a modular structure comprising catalytic modules and non-catalytic carbohydrate-binding modules (CBMs). The largest prokaryotic CBM family, CBM2, contains members that bind cellulose (CBM2a) and xylan (CBM2b), respectively. A possible explanation for the different ligand specificity of CBM2b is that one of the surface tryptophans involved in the protein-carbohydrate interaction is rotated by 90 degrees compared with its position in CBM2a (thus matching the structure of the binding site to the helical secondary structure of xylan), which may be promoted by a single amino acid difference between the two families. Here we show that by mutation of this single residue (Arg-262-->Gly), a CBM2b xylan-binding module completely loses its affinity for xylan and becomes a cellulose-binding module. The structural effect of the mutation has been revealed using NMR spectroscopy, which confirms that Trp-259 rotates 90 degrees to lie flat against the protein surface. Except for this one residue, the mutation only results in minor changes to the structure. The mutated protein interacts with cellulose using the same residues that the wild-type CBM2b uses to interact with xylan, suggesting that the recognition is of the secondary structure of the polysaccharide rather than any specific recognition of the absence or presence of functional groups.

Amino Acid Sequence↗
PubMed2000

Synthesis and biophysical analysis of transmembrane domains of a Saccharomyces cerevisiae G protein-coupled receptor.

The Ste2p receptor for alpha-factor, a tridecapeptide mating pheromone of the yeast Saccharomyces cerevisiae, belongs to the G protein-coupled family of receptors. In this paper we report on the synthesis of peptides corresponding to five of the seven transmembrane domains (M1-M5) and two homologues of the sixth transmembrane domain corresponding to the wild-type sequence and a mutant sequence found in a constitutively active receptor. The secondary structures of all new transmembrane peptides and previously synthesized peptides corresponding to domains 6 and 7 were assessed using a detailed CD analysis in trifluoroethanol, trifluoroethanol-water mixtures, sodium dodecyl sulfate micelles, and dimyristoyl phosphatidyl choline bilayers. Tryptophan fluorescence quenching experiments were used to assess the penetration of the membrane peptides into lipid bilayers. All peptides were predominantly (40-80%) helical in trifluoroethanol and most trifluoroethanol-water mixtures. In contrast, two of the peptides M3-35 (KKKNIIQVLLVASIETSLVFQIKVIFTGDNFKKKG) and M6-31 (KQFDSFHILLINleSAQSLLVPSIIFILAYSLK) formed stable beta-sheet structures in both sodium dodecyl sulfate micelles and DMPC bilayers. Polyacrylamide gel electrophoresis showed that these two peptides formed high molecular aggregates in the presence of SDS whereas all other peptides moved as monomeric species. The peptide (KKKFDSFHILLIMSAQSLLVLSIIFILAYSLKKKS) corresponding to the sequence in the constitutive mutant was predominantly helical under a variety of conditions, whereas the homologous wild-type sequence (KKKFDSFHILLIMSAQSLLVPSIIFILAYSLKKKS) retained a tendency to form beta-structures. These results demonstrate a connection between a conformational shift in secondary structure, as detected by biophysical techniques, and receptor function. The aggregation of particular transmembrane domains may also reflect a tendency for intermolecular interactions that occur in the membrane environment facilitating formation of receptor dimers or multimers.

Amino Acid Sequence↗
PubMed2000

Synthesis and biological evaluation of the geometric farnesylated analogues of the a-factor mating peptide of Saccharomyces cerevisiae.

The a-factor of Saccharomyces cerevisiae is a dodecapeptide pheromone (YIIKGVFWDPAC(Farnesyl)-OCH(3), 1), in which post-translational modification with a farnesyl isoprenoid and carboxymethyl group is required for full biological activity. This peptide has been used as a model system to explore the biological function of the farnesylcysteine moiety, which is found on and required for the biological activity of many key mammalian proteins. The objective of this particular study was the determination of the biological effect of double bond isomerization of the natural E, E-farnesyl moiety on the biological activity of the a-factor. A unified, stereoselective synthetic route to the three geometric isomers of E,E-farnesol (12, 13, and 14) has been developed. The key feature of this synthesis is the ability to control the stereochemistry of triflation of the beta-ketoester 22 to give either 23 or 25. The three farnesol isomers were converted to the corresponding isomeric a-factors (9, 10 and 11) via a modified version of a previously utilized synthetic route. Biological evaluation of these peptides indicates that, surprisingly, all three possess nearly equivalent activity to the natural a-factor bearing the E,E-farnesyl moiety.

Amino Acid Sequence↗
PubMed2000

The actin-driven movement and formation of acetylcholine receptor clusters.

A new method was devised to visualize actin polymerization induced by postsynaptic differentiation signals in cultured muscle cells. This entails masking myofibrillar filamentous (F)-actin with jasplakinolide, a cell-permeant F-actin-binding toxin, before synaptogenic stimulation, and then probing new actin assembly with fluorescent phalloidin. With this procedure, actin polymerization associated with newly induced acetylcholine receptor (AChR) clustering by heparin-binding growth-associated molecule-coated beads and by agrin was observed. The beads induced local F-actin assembly that colocalized with AChR clusters at bead-muscle contacts, whereas both the actin cytoskeleton and AChR clusters induced by bath agrin application were diffuse. By expressing a green fluorescent protein-coupled version of cortactin, a protein that binds to active F-actin, the dynamic nature of the actin cytoskeleton associated with new AChR clusters was revealed. In fact, the motive force generated by actin polymerization propelled the entire bead-induced AChR cluster with its attached bead to move in the plane of the membrane. In addition, actin polymerization is also necessary for the formation of both bead and agrin-induced AChR clusters as well as phosphotyrosine accumulation, as shown by their blockage by latrunculin A, a toxin that sequesters globular (G)-actin and prevents F-actin assembly. These results show that actin polymerization induced by synaptogenic signals is necessary for the movement and formation of AChR clusters and implicate a role of F-actin as a postsynaptic scaffold for the assembly of structural and signaling molecules in neuromuscular junction formation.

Actins↗
PubMed2000

Augmentation of immune responses to HIV-1 and simian immunodeficiency virus DNA vaccines by IL-2/Ig plasmid administration in rhesus monkeys.

The potential utility of plasmid DNA as an HIV-1 vaccination modality currently is an area of active investigation. However, recent studies have raised doubts as to whether plasmid DNA alone will elicit immune responses of sufficient magnitude to protect against pathogenic AIDS virus challenges. We therefore investigated whether DNA vaccine-elicited immune responses in rhesus monkeys could be augmented by using either an IL-2/Ig fusion protein or a plasmid expressing IL-2/Ig. Sixteen monkeys, divided into four experimental groups, were immunized with (i) sham plasmid, (ii) HIV-1 Env 89.6P and simian immunodeficiency virus mac239 Gag DNA vaccines alone, (iii) these DNA vaccines and IL-2/Ig protein, or (iv) these DNA vaccines and IL-2/Ig plasmid. The administration of both IL-2/Ig protein and IL-2/Ig plasmid induced a significant and sustained in vivo activation of peripheral T cells in the vaccinated monkeys. The monkeys that received IL-2/Ig plasmid generated 30-fold higher Env-specific antibody titers and 5-fold higher Gag-specific, tetramer-positive CD8+ T cell levels than the monkeys receiving the DNA vaccines alone. IL-2/Ig protein also augmented the vaccine-elicited immune responses, but less effectively than IL-2/Ig plasmid. Augmentation of the immune responses by IL-2/Ig was evident after the primary immunization and increased with subsequent boost immunizations. These results demonstrate that the administration of IL-2/Ig plasmid can substantially augment vaccine-elicited humoral and cellular immune responses in higher primates.

Amino Acid Sequence↗
PubMed2000

Liver repair and hemorrhage control by using laser soldering of liquid albumin in a porcine model.

BACKGROUND AND OBJECTIVE: We evaluated laser soldering by using liquid albumin for welding liver injuries. Major liver trauma has a high mortality because of immediate exsanguination and a delayed morbidity from septicemia, peritonitis, biliary fistulae, and delayed secondary hemorrhage. STUDY DESIGN/MATERIALS AND METHODS: Eight laceration (6 x 2 cm) and eight nonanatomic resection injuries (raw surface, 6 x 2 cm) were repaired. An 805-nm laser was used to weld 50% liquid albumin-indocyanine green solder to the liver surface, reinforcing it with a free autologous omental scaffold. The animals were heparinized and hepatic inflow occlusion was used for vascular control. All 16 soldering repairs were evaluated at 3 hours. RESULTS: All 16 laser mediated liver repairs had minimal blood loss as compared with the suture controls. No dehiscence, hemorrhage, or bile leakage was seen in any of the laser repairs after 3 hours. CONCLUSION: Laser fusion repair of the liver is a reliable technique to gain hemostasis on the raw surface as well as weld lacerations.

Albumins↗