Biomedical subjects

X Zhu

Publications and source records attributed to X Zhu.

At least 253 records · Page 14Linked to original sources

PubMed2000

Fragile skeletal muscle attachments in dystrophic mutants of Caenorhabditis elegans: isolation and characterization of the mua genes.

Over 30 Caenorhabditis elegans mutants were identified with normal muscle differentiation and initial locomotion followed by catastrophic detachment of skeletal muscles from the body wall. Reducing the strength of muscle contraction in these mutants with a myosin gene mutation suppresses muscle detachment. These dystrophic mutants identify a novel class of genes required for growth and maintenance of functional muscle attachments, not exceptional alleles of genes required for muscle differentiation and contractility. Nine new genes, named mua, and two previously published loci, unc-23 and vab-10, cause fragile musscle attachments. The primary sites of muscle detachment, including the plane of tissue separation, are characteristic for each gene. We suggest these genes identify feedback mechanisms whereby local strain regulates the extent of myofibril contraction and the placement of new muscle attachments in functioning muscles. Finally, we draw some comparisons to vertebrate skin fragility diseases and muscular dystrophies.

Alleles↗

PubMed2000

Effect of platinum coordination complex (PtCx) on citrate uptake by rat renal brush border membrane vesicles (BBMV): direct effect of cisplatin.

Platinosis (severe dermatitis and/or asthma) may be broadly defined as the effects of soluble platinum salts on people exposed to them occupationally. Platinum coordination complexes are widely used in the treatment of a variety of solid tumors. However, the clinical use of cisplatin (the most useful agent) is limited by the development of nephrotoxicity. High dose exposure of soluble platinum could possibly induce nephrotoxicity, occupationally. Urinary citrate is freely filtered at the glomerulus, and its reabsorption in the proximal tubule is the major determinant of rate. In this study, we exposed isolated rat renal brush border membrane vesicles (BBMV) to cisplatin and examined their citrate uptake characteristics. BBMV were prepared by the divalent cation precipitation method. Citrate uptake was measured by the Millipore rapid membrane filtration technique. The preincubation of BBMV with 5 mM of cisplatin for 4 and 8 hours significantly inhibited citrate uptake compared with that of the control BBMV. These findings might contribute to nephrotoxicity in cisplatin therapy.

Animals↗

PubMed2000

Association analysis of variants in the core promoter region of angiotensinogen gene with essential hypertension in Tibetan population.

OBJECTIVE: To detect the variants in the core promoter region of angiotensinogen(AGT) gene, and to analyse the relationship between the AGT gene polymorphisms and essential hypertension in Tibetan population. METHODS: This is a case-control study consisting of 103 essential hypertensive subjects and 82 normotensive controls matched by age and sex. The variants in the AGT gene core promoter region were screened by polymerase chain reaction/single strand conformation polymorphism(PCR/SSCP) and further identified by automated sequencing. The A(-6)G polymorphism was determined in DNA extracted from leucocytes by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). RESULTS: (1) There were two different electrophoresis band patterns in PCR/SSCP analysis. PCR product direct sequencing showed that the two band patterns represented the AA, AC genotypes in the (-20) site of AGT gene respectively. The distribution of A(-20)C genotype was almost identical in essential hypertensive and normotensive groups (P>0.8). The A allele frequency was very high in both groups (control: 0.9175, hypertensive: 0.9124). (2)Distribution of genotype in the (-6) site of AGT gene was much different between the patient group and control group (P<0.005). The frequency of G allele was statistically higher in the patient group than in controls (0.374 vs 0.220, P<0.025). CONCLUSION: Both Tibetan hypertensives and normotensives have higher frequency of A allele in AGT gene (-20) site. The higher frequency of G allele in the AGT gene (-6) site in Tibetan hypertension patients suggests that this allele may be the genetic susceptibility factor in the proceeding of essential hypertension in the Tibetan population.

Angiotensinogen↗

PubMed2000

Development of the antibody repertoire in rabbit: gut-associated lymphoid tissue, microbes, and selection.

Rabbits generate their antibody repertoire in three stages. First, a neonatal repertoire is generated by B lymphopoiesis in fetal liver and bone marrow and is limited by preferential V(H) gene segment usage. Between 4 and 8 weeks after birth a complex primary antibody repertoire is developed by somatically diversifying the neonatal repertoire through somatic hypermutation and a somatic gene conversion-like mechanism in gut-associated lymphoid tissue (GALT). In rabbits, unlike other species, the development of the primary antibody repertoire through somatic diversification of Ig genes appears to be dependent on intestinal microbial flora. The primary antibody repertoire is subsequently modified during antigen-dependent immune responses in which VDJ genes further diversify both by somatic hypermutation and by a gene conversion-like mechanism (the secondary repertoire). During the various stages of development, the antibody repertoire is modified and shaped by selective processes. In this review, we discuss the roles of GALT, microbes, and B-cell selection in generating antibody diversity in rabbits.

Animals↗

PubMed2000

Mechanism of capacitative Ca2+ entry (CCE): interaction between IP3 receptor and TRP links the internal calcium storage compartment to plasma membrane CCE channels.

Activation of cells by agents that stimulate inositol trisphoshate (IP3) formation causes, via IP3 receptor (IP3R) activation, the release of Ca2+ from internal stores and also the entry of Ca2+ via plasma membrane cation channels, referred to as capacitative Ca2+ entry or CCE channels. Trp proteins have been proposed to be the unitary subunits forming CCE channels; however, there is no definitive proof for this hypothesis. We have now identified amino acid sequences of a Trp and of an IP3R that interact to form stable complexes. These complexes appear to form in vivo, as evidenced by co-immunoprecipitation of Trp with IP3R and by the fact that expression of the respective interacting sequences modulates development of CCE brought about by store depletion. The finding that a Trp-interacting sequence of IP3R interferes with natural CCE leads us to conclude that Trp proteins are, indeed, structural members of CCE channels. We conclude further that direct coupling of IP3R to Trp is a physiological mechanism by which cells trigger CCE in response to signals that stimulate phosphoinositide hydrolysis and IP3 formation. Pros and cons of various CCE activation models are discussed.

Amino Acid Sequence↗

PubMed2000

Studies on the resuscitative efficacy of polymerized bovine hemoglobin.

The paper described modified hemoglobin (Hb) with glycolaldehyde for the efficacy on resuscitation of severe hemorrhagic shock. Our objective was to compare the effect on resuscitation of severe hemorrhagic shock with different experimental groups. Results showed early resuscitation with modified bovine Hb is superior to lactated Ringer's solution group in improving hemodynamic and acidosis, but the effect of polymerized Hb with glycolaldehyde were similar to fresh whole blood in this rat model.

Acetaldehyde↗

PubMed2000

[Multislice CT: principles and new CT-scan applications].

The introduction of new array detector technology for multislice CT improves CT-scan capabilities. Compared to single-slice helical CT, this technique offers three significant advantages: the pitch can be increased by a factor of 4, resulting in shorter acquisition times and contrast media saving, the temporal and spatial resolution are improved and the slice thickness can be freely and retrospectively selected. This technique promises to revolutionize radiological practice, just as spiral systems did a decade ago. Multislice CT is particularly suitable for exploring the chest, the heart and the vessels. It is also specially useful for musculo-skeletal explorations and trauma patients.

Animals↗

PubMed2000

[Analyses on the association of CA-repeat polymorphism and A1166-->C variant in the 3'-flanking region of AT(1)R gene with essential hypertension in Tibetans].

OBJECTIVE: To investigate whether CA-repeat polymorphism and A1166 --> C variant in the 3n-flanking region of AT(1)R gene are in association with the genetic susceptibily to essential hypertension (EH) in Tibetans. METHODS: A case-control study was carried out. Sibpair analysis and family linkage analysis were conducted. The CA-repeat polymorphism of AT &(1) R gene was identified by polymerase chain reaction(PCR) with fluorescence labeled dCTP as substrate and by semi-automatic sequence technology. The A1166 -->C variant was detected by PCR-RFLP. RESULTS: Association of AT&(1)R gene locus with EH was confirmed through the case-control study in well-characterized group of 113 Tibetan EH patients and 131 normotensives(chi(2)=26.44, P<0.001). A closer examination of this gene locus found 11 alleles from Tibetan population; allele A7 (138 bp) was more frequent in both the patients and the controls. Allele A8(140 bp) was in strong positive association with genetic susceptibility to EH in Tibetans. Frequency of allele A8 was 20.5% in EH and 7.3% in normotensives. The difference of allele frequencies between the groups was significant (chi(2)=9.64, P=0.002, OR=3.46, 95% CI 1.44-8.51). Affected sibpair analysis showed chi(2)=3.85, P=0.025; family linkage analysis gave Lod score of 0.80. No association between A1166 --> C variant in AT(1)R gene and EH in Tibetans was observed (P>0.05). CONCLUSION: The result suggests that CA-repeat polymorphism of AT(1)R gene be in association with EH in Tibetans, which implicates that AT(1)R gene may be in linkage disequilibrium with the causative genes of EH.

Adult↗

PubMed2000

[Chromosome localization of the dentinogenesis imperfecta type II locus].

OBJECTIVE: To scrutinize the linkage between dentinogenesis imperfecta type II and chromosome 4q21 in a Tianjin-Tanggu family. METHODS: Blood samples were collected from 13 members of the family. DNA was analyzed with 4 short tandem repeat polymorphisms markers UGATA62A11, DSP(P), SPP1 and D4S1563 Y using fluorescence-based PCR. The linkage between four markers on chromosome 4q21 and dentinogenesis imperfecta type II was tested by Lod score analysis. RESULTS: GATA62A11 and DSP(P) suggested linkage and yielded a Lod score of 1.63 at theta =0, and 1.68 at theta =0 by means of the MLINK software, respectively. Genotype and haplotype were acquired. CONCLUSION: The disease gene of the dentinogenesis imperfecta type II family is located on chromosome 4q. The result will be helpful for the further identification of the dentinogenesis imperfecta type II gene.

Chromosome Mapping↗

PubMed2000

[The effect of polylactide screws on fracture healing].

This experiment aimed at investigating the effect of a kind of home-bred poly-DL-lactide screws on fracture healing. An operation was performed so as to make bilateral lateral condylar fractures of the femur in 8 dogs. The left sides were fixed with 2 home-bred PDLLA(Mv = 43 x 10(4)) screws, and the contralateral sides were fixed with 2 metalic screws to be used as controls. The animals were sacrificed at 2, 4, 8, and 12 weeks after surgery. Optic microscopy and SEM photography were done. The results of optic microscopy showed that fibrous callus formed already in both groups by 2 weeks after surgery, and bilateral fractures united uneventfully by 12 weeks. Although the course of fracture healing in experimental group was slower than that in control group, the osteogenesis in experimental group appeared to be normal. The SEM examination demonstrated that collagenous fibers arranged regularly and calcified normally in both groups at 12 weeks. And many square and rhomboid granules produced from the degradation of PDLLA material were found in experimental group at 12 weeks. Therefore, it is suggested that this kind of home-bred PDLLA screws should be applicable to fractures where the tissues are rich in blood supply.

Animals↗

PubMed2000

[The construction and physical-mechanical characterization of polymer foams of D. L-PLA].

This study was intended to construct biogradable polymer foam used in tissue engineering. The D. L-PLA was supplied by chengdu institute of organic chemistry. Biogradable polymer membranes were prepared with a novel solvent-casting particulate-leaching technique, then, the constituent membranes with the proper order were laminated to produce three-dimensional foams with continuous pore structure and morphology. Afterwards, the physical-mechanical property of polymer foams were tested. The test results indicated that the lamination process did not change the physical-mechanical property of the polymer membranes.

Biocompatible Materials↗

PubMed2000

[Recent advance in studies of new intraaortic axial flow pump: "dynamic aortic valve"].

We have previously proposed and demonstrated the feasibility of a new concept of intraaortic axial flow blood pump, termed "Dynamic Aortic Valve(DAV)". Implanted in the position of aortic valve, DAV can serve as either an assistant pump or a mechanical valve subjected to the power input. It has several merits over the traditional axial blood pumps: (1) better anatomic compatibility and biologic compatibility; (2) little foreign material is to be introduced into the corporeality; (3) better resistance to infection; (4) puncturing power line could be eliminated; (5) promoting the failing heart to recovery; (6) simpler structure and better durability. In our recent studies, the structure of DAV is further simplified and performance improved greatly. The structure of DAV is merely an impeller fixed to a magnetic rotor while held by a central shaft hanging from a rigid supporting cage. The rotor-impeller can be driven by an alternative magnetic field derived from a remote magnet, implying that the magnetic source can even be arranged extracorporeally. The DAV can be driven by a rotational magnet placed at a distance of 60 mm. At the state of maximal output of hydraulic power, the flow rate (FR) generated by DAV reaches 5 L/min against an afterload of 70 mmHg(1 mmHg = 0.133 KPa). The maximal pressure differential (PD) maintained by DAV is 131 mmHg. The results further revealed the feasibility of the concept of DAV.

Aortic Valve↗

PubMed2000

[Mechanical mechanism in plastic stage of fracture union--application of bone surface remodeling theory].

In this paper is presented a discussion on the mechanical mechanism in the plastic stage of fracture union. We adopt the bone surface remodeling theory in conjunction with finite element method, choose the strain energy density as mechanical stimulus, work at a three-dimensional finite element model, and then we investigate the mechanical mechanism in the plastic stage of fracture union in three types: exterior osteotylus, interior bony defect and exterior bony defect, using long bone surface remodeling software "BRSS97" we design. The results show that osteotylus can be completely absorbed, and bony defect can recover. For all the three types, the final bone configuration resembles normal state bone configuration. It proves that long bone configuration in the plastic stage of fracture union is the result of the adaptation of bone to loading environment.

Biomechanical Phenomena↗

PubMed2000

[Study on COL7A1 gene mutation in a epidermolysis bullosa pruriginosa family].

OBJECTIVE: To identify gene mutation of a epidermolysis bullosa pruriginosa family. METHODS: Polymerase chain reaction (PCR), DNA sequencing, multiplex PCR using allele-specific oligonucleotide primers. RESULTS: A G6100A transition of COL7A1 was found in patients, resulting in G2034R substitution in type VII collagen. The mutation was not found in control normal individuals. CONCLUSION: The mutation of G2034R is the underlying cause of epidermolysis bullosa pruriginosa in this family, not common polymorphism.

Collagen↗

PubMed2000

[The promoting effects of mGM-CSF gene modified tumor vaccine immunization on peritoneal antigen presenting cells in mice].

OBJECTIVE: To investigate the effects of immunization with granulocyte-macrophage colony-stimulating factor (GM-CSF) gene-modified tumor vaccine on the number and function of antigen presenting cells (APCs). METHODS: FBL-3 murine erythroleukemia cells were transfected with mGM-CSF recombinant adenovirus and then irradiated to prepare vaccine. The specific cytotoxic T lymphocyte(CTL) activity in vivo and survival of the mice i.p. immunized with this vaccine were observed. The percentage of 33D1+ dendritic cells(DCs) in peritoneal adherent cells were analyzed with flow cytometry. The number of peritoneal cell and function of peritoneal adherent cells of immunized mice were also investigated. RESULTS: High level of specific CTL activity were induced in the mice i.p. immunized with this vaccine and all of the mice were resistant to the subsequent challenge with the parental FBL-3 cells. The number of peritoneal APCs-increased. FACS analysis showed that the percentage of 33D1+ DCs in peritoneal adherent cells also increased. The allo-mixed lymphocyte reaction(MLR) stimulating activity of these APCs was enhanced. CONCLUSION: mGM-CSF gene-modified tumor vaccine has potent anti-tumor effect, and this may be related to the increased number and function of peritoneal APCs induced by mGM-CSF through paracrine mechanism at the vaccination site.

Animals↗

PubMed2000

[In vitro testing of a new implantable ventricular assist rotary pump made in China].

We have measured the hemodynamic properties of the rotary pump in order to give directions for use in animal test and even in clinical application. In our mocking circulation circuit, under definite preload, the inner diameter of inlet and outlet cannulae and the afterload have been changed for measuring the pressure of input and output of the pump and the pump flowing rate when it runs under 75% maxim working condition. The results demonstrate that with the cannulae of inner diameter of 8 mm as drainage, the pump provides 5.32 L/min of output against a mean afterload of average 60 mmHg(1 mmHg = 0.133 kPa) with a filling pressure of 10 mmHg. With the cannulae usually used in clinical setting, the flowing rates are more than 1.5 L/min against a mean afterload of 90 mmHg, and all output pressure of the pump is higher than 120 mmHg. In conclusion, the volume of the rotary pump is small, the needed power is low, and the hemodynamic parameters are suitable for animal test and even for clinical use.

China↗

PubMed2000

[Diagnostic efficacy of glutamic acid decarboxylase antibody and islet cell antibody in type I diabetes mellitus].

OBJECTIVE: To investigate the diagnostic efficacy of glutamic acid decarboxylase antibody (GAD65-Ab) and islet cell antibody (ICA) in type I diabetes mellitus. METHODS: 104 cases of type I diabetes mellitus and 102 normal controls were recruited, GAD65-Ab was determined with radioligand assay and ICA with ELISA. The diagnostic efficacy of GAD65-Ab and ICA was analysed by receiver-operating characteristic (ROC) curve with sensitivity, specificity and curve area. RESULTS: (1) The optimal cut-off point of GAD65-Ab was at 0.30, while that of ICA was at 0.45. The area under the curve of GAD65-Ab and ICA were 0.835 and 0.715 respectively. Compared with 0.5, the area under curve of GAD65-Ab and ICA was higher (P < 0.0001). The area under curve of GAD65-Ab was higher than that of ICA(P < 0.01). (2) In type I diabetes mellitus patients, the positivity of GAD65-Ab was not correlated to the age of onset and duration of the disease, while the positivity of ICA was correlated to the age of onset and duration. CONCLUSION: Type I diabetes mellitus can be diagnosed with GAD65-Ab and ICA. The diagnostic efficacy of GAD65-Ab is higher than that of ICA. In patients of type I diabetes mellitus with adult-onset and duration more than one year, the diagnostic efficacy of GAD65-Ab is higher than that of ICA, while in patients of type I diabetes mellitus with adolescent-onset and duration less than one year, the diagnostic efficacy of ICA is higher than that of GAD65-Ab.

Adolescent↗

PubMed2000

Polymorphisms of TAP, LMP and HLA-DM genes in the Chinese.

OBJECTIVE: To investigate the distribution of antigen-processing genes transporter associated with antigen processing (TAP), low molecular weight proteasome (LMP2) and HLA-DM in the Shanghai population and to explore the possible role of these genes in the genetic susceptibility to autoimmune diseases IgA nephropathy(IgAN) and multiple sclerosis(MS). METHODS: Eighty normal Shanghai Chinese, 60 patients with IgAN and 21 patients with MS were randomly selected and genotyped for antigen-processing genes (TAP1, TAP2, LMP2, HLA-DMA and -DMB) using polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Two-locus linkage disequilibrium analysis was performed. RESULTS: Four TAP1, 6 TAP2, 2 LMP2, 3 DMA and 4 DMB alleles were observed. Statistically significant associations were found between TAP1B-TAP2A, TAP1B-LMP2H and TAP2D-HLA-DMA* 0101 (Pc < 0.01). There was no association between antigen-processing genes and either IgAN or MS. CONCLUSION: The polymorphisms of antigen-processing genes in this Shanghai population are similar to those observed in the other ethnic populations. No association was found between IgAN or MS and any antigen-processing genes tested in Shanghai population.

ATP Binding Cassette Transporter, Subfamily B, Mem↗