Tissue engineering of the musculo-skeletal system--basic research and clinical applications.
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Animals↗
Biomedical subjects
Z Yang
Publications and source records attributed to Z Yang.
Microtubule-based transport systems in neurons: the roles of kinesins and dyneins.
The large size and extreme polarization of neurons is crucial to their ability to communicate at long distances and to form the complex cellular networks of the nervous system. The size, shape, and compartmentalization of these specialized cells must be generated and supported by the cytoskeletal systems of intracellular transport. One of the major systems is the microtubule-based transport system along which kinesin and dynein motor proteins generate force and drive the traffic of many cellular components. This review describes our current understanding of the functions of kinesins and dyneins and how these motor proteins may be harnessed to generate some of the unique properties of neuronal cells.
Animals↗
Molecular determinants for the distinct pH sensitivity of Kir1.1 and Kir4.1 channels.
Kir1.1 (ROMK1) is inhibited by hypercapnia and intracellular acidosis with midpoint pH for channel inhibition (pK(a)) of approximately 6.7. Another close relative, Kir4.1 (BIR10), is also pH sensitive with much lower pH sensitivity (pK(a) approximately 6. 0), although it shares a high sequence homology with Kir1.1. To find the molecular determinants for the distinct pH sensitivity, we studied the structure-functional relationship using site-directed mutagenesis. An NH(2)-terminal residue (Lys-53) was found to be responsible for the low pH sensitivity in Kir4.1. Mutation of this lysine to valine (K53V), a residue seen at the same position in Kir1. 1, markedly increased channel sensitivity to CO(2)/pH. Reverse mutation on Kir1.1 (V66K) decreased the CO(2)/pH sensitivities. Interestingly, mutation of these residues to glutamate greatly enhanced the pH sensitivity in both channels. Other contributors to the distinct pH sensitivity were histidine residues in the COOH terminus, whose numbers are fewer in Kir4.1 than Kir1.1. Mutation of two of these histidine residues in Kir1.1 (H342Q/H354N) reduced CO(2)/pH sensitivities, whereas the creation of two histidines (S328H/G340H) in Kir4.1 increased the CO(2)/pH sensitivities. Combined mutations of the lysine and histidine residues in Kir4.1 (K53V/S328H/G340H) gave rise to a channel that had CO(2)/pH sensitivities almost identical to those of the wild-type Kir1.1. Thus the residues demonstrated in our current studies are likely the molecular basis for the distinct pH sensitivity between Kir1.1 and Kir4.1.
Amino Acid Sequence↗
Organizations and gene duplications of the human and mouse MHC complement gene clusters.
The MHC complement gene cluster (MCGC) in most people contains thirteen structural genes, pseudogenes and gene segments. Novel genes RD, SKI2W, DOM3Z and RP1 are organized as two head-to-head gene pairs between complement gene Bf and the first locus of C4. Southern blot analysis shows that single-copy genes for DOM3Z are detectable in primates and other mammals. Sequence analyses revealed that the exon- intron structures of human and mouse DOM3Z genes are identical. Both human and mouse DOM3Z transcripts exhibit splice variants at the 5' regions, although the open reading frames remain identical. Cloning and characterization of the mouse RP1 cDNA revealed a reading frame for 254 amino acids with a bipartite nuclear localization signal close to the amino terminus. The mouse RP1 gene consists of 7 exons and spans 12.9 kb. Located in intron 4 of mouse RP1 is an endogenous retrovirus that probably confers the androgen-responsive expression of the Slp protein in certain male mice. The availability of the complete human and mouse MCGC genomic and cDNA sequences allows further deliberate analyses of gene duplications and evolution. The intergenic region between mouse SLP and C4 genes is more than six times larger than the corresponding region in humans. It contains the functional gene steroid CYP21A, long stretches of repetitive DNA elements, and three partially duplicated gene segments TNXA, SKI2W2 and RP2. The modular duplications of human and mouse RP-C4-CYP21-TNX (RCCX) are sharply different as SKI2W2 is absent in the human MCGC, and TNXA and RP2 are smaller in size but higher in sequence conservation in humans.
Amino Acid Sequence↗
Relating physicochemical properties of amino acids to variable nucleotide substitution patterns among sites.
Markov-process models of codon substitution were implemented that account for features of DNA sequence evolution (such as transition/transversion bias and codon usage bias) as well as heterogeneity of amino acid substitution pattern over sites. The codon (amino acid) sites are assumed to come from several classes (such as secondary structure categories), among which the rate of amino acid substitution and the effect of amino acid chemical properties vary. Parameters are estimated by the maximum likelihood method, which accounts for the phylogenetic relationship among species and corrects for multiple hits at the same site. The likelihood ratio test is used to compare models. Mitochondrial cytochrome b genes of 28 primate species are analyzed. The site-heterogeneity models provide much better fit to previous homogeneous models.
Amino Acid Substitution↗
[Physical location and detection of homologous sequences of proto-oncogene ras on maize].
Proto-oncogene ras is an important gene for suppress the animal cells apoptosis. To analyze the presence of homologous sequences of ras in maize and rice, Southern blot hybridization was performed and positive signals was detected in these two species' genomes. The physical location of the ras homologous sequences was also carried out in maize chromosome by FISH. ras was hybridized onto the long arm of the chromosomes 2 and 7. The detection rates of FISH were 10.85% and 14.15%, and percentage distances from centromere to detection sites were 54.92 +/- 1.90 and 94.62 +/- 2.77 respectively. These results provided important clues of the further research of plant apoptosis.
Apoptosis↗
[Study on tissue engineering of muscular skeletal system].
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Animals↗
A nine-year prospective study on the incidence of childhood type 1 diabetes mellitus in China.
To investigate the epidemiological characteristics of childhood type 1 diabetes mellitus in China, newly diagnosed cases of type 1 diabetes with an onset age under 15 years were retrospectively registered by 23 local centers in China following a standardized protocol on the basis of the nationwide registry established by the WHO DiaMond Project China Participating Center, Chinese Academy of Preventive Medicine (CAPM). A population of about 24 million children were covered in the defined areas. A two-sample capture-recapture method was used to estimate case ascertainment. Between 1988 and 1996, 903 diabetic cases were registered in 9 ethnic groups. The overall ascertainment corrected incidence rate (IR) was 0.59 per 100,000 person-year. The IR was 0.52/100,000 (95% CI: 0.50-0.54) for males and 0.66/100,000 (95% CI: 0.64-0.68) for females. The standardized ascertainment corrected IR by the national age-specific population in 1990 was 0.57 per 100,000 person-year. The incidence among various ethnic groups ranged from 0.25/100,000 to 3. 06/100,000. The IRs increased with northern latitude, and the IR of Han population was significantly higher in North China compared with South China (0.67 versus 0.53 per 100,000 respectively, P < 0.01). A correlation model of incidence and calendar time showed that the IR increased significantly between 1988 and 1996 (r = 0.86, P = 0.0027). The relative risk (RR) of type 1 diabetes mellitus for different age-groups estimated by a Poisson regression model showed that taking RR as 1.00 for age-group from 0 to 4 years, the RR for age-group from 5 to 9 year and from 10 to 14 year was 2.30 and 3.60 respectively. The standardized ascertainment corrected IR of childhood type 1 diabetes mellitus in China in much lower than in other countries. The geographic and ethnic variability of the incidence suggests that both genetic and environmental factors play a role in the development of childhood diabetes in China.
Adolescent↗
[Preliminary study on pathogenicity of hepatitis G virus].
OBJECTIVE: To study the clinical, enzymatic and liver pathological changes in patients with hepatitis G virus (HGV) infection. METHODS: RT- nested PCR was applied to detect HGV RNA in 368 patients with hepatic diseases. The liver biopsy tissue from one liver cirrhosis patient with simple HGV infection was examined. RESULTS: Simple HGV RNA positive were found in 7 cases of 71 acute hepatitis jaundice, in 22 cases of 155 chronic hepatitis and in 3 cases of 51 liver cirrhosis. The immunohistochemistry of the liver biopsy tissue from a liver cirrhosis patient showed HGV NS5 antigen positive. However, HGV infection might occur simply or in combination with hepatitis B or C virus or super infected. CONCLUSIONS: HGV RNA could be detected in acute hepatitis jaundice, chronic hepatitis, hepatitis B or C carriers, liver cirrhosis and hepatocellular carcinoma. HGV is proved to be a hepatotropic virus by pathological examination and immunohistochemistry, the virus located in the cytoplasm of the liver cells. It may cause chronic hepatitis and even liver cirrhosis, so HGV is pathogenic to liver tissue.
Adolescent↗
[Impact of precipitation and underground water level in the edge of oases on growth and decline of Nitraria tangugtorum community].
Based on the data from underground water monitoring, meterological measuring and fixed sample square investigating in successive years at the edge of the oasis in Minqin, Gansu, the impact of precipitation and underground water on the growth and decline of Nitraria tangutorum community was studied. The result showed that the desiccated environment in oases driven by the decline of underground water level was favorable for the growth and develoment of N. tangutorum community, and made this species more xerophilous. This declining underground water level was not a limiting factor for N. tangutorum growth in late years. These N. tangutorum-dominated communities were predicted to survive comparatively longer, and to function as sand fixer and wind breaker at oasis edge in Minqin. When average annual precipitation was about 110 mm, N. tangutorum would maintain its normal growth, but the community couldn't spread freely. Only when the annual precipitation was up 140 mm in two years running, could its growth be improved.
Chemical Precipitation↗
[Primary identification of organic compounds in soybean rhizospheric soil on continuous and alternate cropping and their allelopathy on soybean seed germination].
Organic compounds extracted with ethanol (OCEWE) from soybean rhizospheic soil on continuous and alternate cropping at pod-string were identified by gas chromatography-mass spectrometry (GC-MS). The results showed the compounds mainly include organic acids, alcohol, acetone, aldehyde, naphthalene phenyl and furan hydrocarbon, many of which were reported as allelochemcals. Under this experiment condition, OCEWE did not show any allelopathy on soybean seed germination and radicle growth, which might be related with their critical toxicity concentrations. In addition, the relationship between allelopathy and barrier on soybean continuous and alternate cropping was also discussed.
Acids↗
[Obstetrical outcome of pregnancy on in vitro fertilization and embryo transfer 128 cases analysis].
OBJECTIVE: To evaluate the obstetrical outcome of in vitro fertilization and embryo transfer (IVF-ET) pregnancy. METHODS: This study compared the obstetrical outcome of 128 cases of IVF-ET pregnancy with that of 11,372 natural pregnancies as control group. RESULTS: There were 20.3%(26/128) multiple pregnancy, 20.3%(26/128) premature birth, 14.8%(19/128) pregnancy induced hypertension, 25.5%(41/161) small for gestational age, 88.3% (113/128) cesarean section rate and 31.1@1000(5/161) perinatal mortality in the IVF-ET group. However, these data in the control group were 3.3%(380/11,372), 1.0%(119/11,372), 7.6%(863/11,372), 3.6%(416/11,492), 34.7%(3,946/11,372) and 8.9@1000 (102/11,492), respectively. CONCLUSION: The incidence of obstetrical complications was significantly higher in IVF-ET pregnancy. Multiple pregnancy is a high risk factor.
Adult↗
[Cloning and antitumor activity of angiogenesis inhibitor HIAF-1].
OBJECTIVE: A new angiogenesis inhibitor HIAF-1 (human inhibitor angiogenesis factor-1) was cloned, expressed in E. coli and its antitumor activity was studied. METHODS: HIAF-1 was amplified by RT-PCR from human fetal liver tissue, then cloned into pET30a(+) vector and expressed in E. coli BL21:DE3 after sequencing. In vitro endothelial proliferation inhibiting activity of HIAF-1 was examined by MTT method. In vivo antitumor activity was studied in a murine model of IVTA2MA-891. RESULTS: HIAF-1 was first cloned from human fetal liver tissue. Sequence analysis of the inhibitor revealed identity to a c-terminal fragment of human collagen XVIII. HIAF-1 was effectively expressed in E. coli with a yield of 88 mg/L. Recombinant HIAF-1 protein could inhibit endothelial cell proliferation in vitro with an IC50 value of 7.5 micrograms/ml. In vivo studies showed that HIAF-1 inhibited growth rate of the primary tumor by 46.6% and metastasis by 68.9%. CONCLUSION: The cloned and the bio-engineering product of HIAF-1 is an angiogenesis inhibitor, capable of inhibiting tumor growth and metastasis.
Angiogenesis Inhibitors↗
[Materials fabrication of tissue engineered peripheral nerve in vitro].
OBJECTIVE: To investigate the methods to fabricate repair materials of tissue engineered peripheral nerve with bioactivity of Schwann cells (SC). METHODS: 1. The materials were made by dry-wet spinning process to fabricate PLA hollow fiber canal with external diameter of 2.3 mm, internal diameter of 1.9 mm, thickness of 0.4 mm, pore size of 20 to 40 microns, pore ratio of 70% and non-spinning fiber net with pore size of 100 to 200 microns, pore ratio of 85%. 2. SC were implanted into excellular matrix (ECM) gel to observe the growth of SC. 3. SC/ECM complex were implanted into non-spinning PLA fiber net to observe the growth of SC. 4. SC, SC/ECM and SC/ECM/PLA were implanted into PLA hollow fiber canal to bridge 10 mm defect of rat sciatic nerve. RESULTS: 1. SC were recovered bipolar shape at 1 day after implantation, and could be survived 14 days in ECM gel. 2. After SC/ECM complex was implanted into PLA net, most of SC were retained in the pore of PLA net with the formation of ECM gel. SC could be adhered and grown on PLA fiber. 3. Most of SC in ECM gel could be survived to 21 days after transplantation. Survival cell numbers of SC/ECM and SC/ECM/PLA groups were obviously higher than SC suspension group. CONCLUSION: Non-spinning PLA porous biodegradable materials with ECM is benefit for SC to be adhered and grown.
Acrylic Resins↗
[Research on drug-resistant gene of nontuberculous mycobacteria].
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Anti-Bacterial Agents↗
[A preliminary study of viral cross-transmission in dentistry].
OBJECTIVE: To research the viral cross-transmission of a DNA virus (HBV) and a RNA virus (HCV) in dentistry. METHODS: Five plans were designed to sterilize the oral instruments that had been infected with HBV or HCV positive serum. HBsAg, HBV-DNA, anti-HCV, HCV-RNA were detected before and after sterilization. RESULTS: All methods could effectively clean the specific proteins (HBsAg/anti-HCV) and nucleic acids (HBV-DNA/HCV-RNA) of the infected virus. CONCLUSION: The instruments which have been sterilized should not be the main way of the cross-transmission of virus in dentistry.
Antigens, Viral↗
[Vascular lesion and its mechanisms in spleen under statement of portal hypertension].
OBJECTIVE: To investigate the vascular lesion and its mechanisms in spleen in patients with portal hypertension. METHODS: 28 specimens of spleen from portal hypertension patients and 10 from normal controls were stained by HE and Masson Trichrome to study their vascular pathological lesions. The proteins of PCNA, and Flt-1 were analyzed by immunohistochemistry. The mRNAs of VEGF and bFGF were also identified with in situ hybridization. RESULTS: Various vascular lesions occurred, such as sclerosis endangitis fibrosis and endothelial cell damage. The proteins of PCNA, and Flt-1 were intensively immunostained in portal hypertension spleens compared with normal controls. The mRNAs of VEGF and bFGF were highly expressed, but weakly in controls. CONCLUSIONS: (1) Vascular lesion of spleen is one part of portal hypertensive vascular lesions. (2) The mechanisms of these lesions are due to the changes of microcirculation and hemodynamics, immune disorders, increasing growth factors such as VEGF, Flt-1 and bFGF both at protein and transcription levels.
Adolescent↗
[Magnetic resonance angiography in assessing changes of pre-and post-disconnective portal system in patients with portal hypertension].
OBJECTIVE: To evaluate the role of magnetic resonance angiography (MRA) in assessing the portal system changes in patients with portal hypertension after pericardial devascularization and splenectomy. METHODS: The portal diameter, blood velocity and flow, collateral circulation, variceal vein and other portal parameters of 15 patients with portal hypertension receiving pericardial devascularization and splenectomy and splenectomy were comparatively evaluated with Siemens 1.5 T MRI 1 week before operation and 2 weeks after operation. RESULTS: The portal diameters decreased after operation, with the disappearance or alleviation of esophageal and fundal variceal veins. In 15 patients, 9 showed. The blood velocity and flow of the portal veins were lower postoperatively. than those preoperatively; In 15 patients, 9 showed increased gastric imaging intensity after operation. CONCLUSIONS: MRA can provide high quality and concrete 3-dimensional information about the portal system and hemodynamics of portal hypertensive patients. It is an important non-invasive way in evaluating the effects of operations and long-term follow-up. Postoperative gastric venous congestion possibly causes increased portal hypertensive gastropathy after disconnection.
Blood Flow Velocity↗