[Responses of radial growth of Fraxinus mandshurica from different provenances to climate at Maoershan in Northeast China]. / 东北地区帽儿山种源实验林区不同种源水曲柳径向生长对气候的响应.

To understand the responses of radial growth of Fraxinus mandshurica from different provenances to climatic factors, we used the dendrochronological method to establish the standard chronologies of F. mandshurica from 20 provenances in Maoershan provenance test forest, and analyzed the differences in radial growth and their correlation with climate factors. The results showed that the overall trend of F. mandshurica chronologies from 20 provenances was generally similar. There were differences in growth amplitude, with the average radial growth of F. mandshurica from Dailing, Lushuihe and Sanchazi being the highest. The radial growth of F. mandshurica from 20 provenances was significantly positively correlated with the highest temperature in July and the average temperature in July except for Huinan. The radial growth of F. mandshurica from 14 provenances was significantly positively correlated with the precipitation in August. The radial growth of F. mandshurica was constrained by temperature and precipitation during the growing season. There was difference in radial growth among F. mandshurica from different provenances under drought stress. F. mandshurica from Wangqing, Dailing, and Hailin had stronger resistance to drought, while that from Wandianzi, Zhanhe, and Xinglong had better recovery ability after drought.

[Telomere Length, Expression of MRE11 and Ku80 in Patients with Aplastic Anemia and Their Correlation with Pathogenesis].

OBJECTIVE: To detect the expression levels of MRE11 and Ku80 mRNA, and telomere length in bone marrow mononuclear cells of aplastic anemia(AA) patients, and to explore their correlation with pathogenesis of aplastic anemia. METHODS: Bone marrow mononuclear cells were collected from 40 cases of AA and 20 normal controls for detecting mRNA expression of MRE11 and Ku80 and telomere length by using real-time quantitative polymerase chain reaction (qPCR), then MRE11, Ku80 and telomere length were analyzed for their correlation. RESULTS: As compared with controls, the expression levels of MRE11 and Ku80 in patients with AA were significantly reduced, and the telomere length in patients with AA was obviously shortened, respectively (P<0. 05). The telomere length was significantly shorter in the persons aged ≥45 years in comparison with the AA patients and normal control younger than 45 years old (P<0.05). For the AA patients older than or equal to 45 years and less than 45 years in comparison with the controls at the same age, the telomere length was significantly shorter(P<0.05). The expression levels of MRE11 and Ku80 didn't correlate with telomere length (P>0.05). The mRNA expression level of MRE11 correlated positively and significantly with that of Ku80 (r=0.863, P<0.05). CONCLUSION: The change of telomere length may play an important role in the pathogenesis and progression of aplastic anemia. The lower expression of MRE11 and Ku80 may be involved in the pathogenesis of aplastic anemia.

Chemical-physical characterization of polyurethane catheters modified with a novel antithrombin-heparin covalent complex.

Detailed structural studies were made of polyurethane catheter surfaces modified with a covalent antithrombin-heparin (ATH) complex that has superior anticoagulant activity compared to unfractionated heparin. ATH was grafted onto polyurethane catheters by surface film preparation involving a three-step process: (1) activation of ATH through functionalized poly(ethylene glycol) (PEG), (2) base-coating treatment of the polyurethane surface and (3) final attachment of ATH onto the surface by free radical polymerization. With the application of base coating, composed of polyhydroxyethylmethacrylates and poly(ethylene oxide) (PEO), the coating process could easily be transferred to other biomaterials by adjusting the base-coating composition. Anti-factor Xa assays confirmed high anticoagulant activity of the ATH coatings. To determine structural aspects critical for biological function, the product was analyzed using differential scanning calorimetry and SDS-PAGE. Radiolabeled ATH was used to determine the graft density, homogeneity and stability of modified surfaces, as well as the competition of PEO-ATH migration to the surface with self-aggregation of the PEO-ATH molecules during the coating process. X-ray photoelectron spectroscopy was used to investigate the surface chemical composition before and after ATH application. Analysis showed that PEO-ATH was strongly surface-bound at a final density of 15-200 pmol/cm(2), depending on the incubation concentration.

Extent of linkage disequilibrium in wild and domestic chicken populations.

Linkage disequilibrium (LD) analyses play a fundamental role in gene mapping, both as a tool for fine mapping of complex trait gene and in genome-wide association studies. The use of LD analyses in practice depends crucially on the understanding of the patterns of LD in the genome. In the present study, a total of 36 SNP were selected initially in a region (200 kb) of Contig.060226.1 on GGA1 based on the average physical distance. After verifying their level of polymorphism, 21 SNP were selected finally to genotype one wild and two domestic chicken populations, Red Jungle Fowl (RJF), Taihe Silkie chicken (TS) and White Recessive Rock chicken (WRR). Two distinct measures of linkage disequilibrium, D' and r(2), between marker pairs were used. The D'map of RJF is spurious. Many marker pairs showed complete LD. TS and WRR showed distinct characteristic of decreasing D' value over increasing physical distance. The r(2) showed much less inflation than did D' in RJF population, and also showed a characteristic decreasing value over increasing physical distance. In TS and WRR populations, although the two measures differed in scale, their decay profiles were similar. The data in the present study suggested that the extent of LD in this region is about 150 kb, corresponding to 0.4 cM. Our results imply that a very dense map of SNP markers will be required for LD mapping methods. Thus, association studies based on polymorphisms within all known genes, and candidate QTL mapping, may ultimately prove to be a more effective strategy.

Protein adsorption on polyurethane catheters modified with a novel antithrombin-heparin covalent complex.

Highly anticoagulant covalent antithrombin-heparin complex (ATH) was covalently grafted onto polyurethane catheters to suppress adsorption/activation of procoagulant proteins and enhance adsorption/activation of anticoagulant proteins for blood compatibility. Consistency of catheter coating was demonstrated using immunohistochemical visualization of ATH. The ability of the resulting immobilized ATH heparin chains to bind antithrombin (AT) from plasma, as measured by binding of (125)I-radiolabeled AT, was greater than that for commercially-available heparin-coated catheters, and much greater than for uncoated catheters. Complementary measurements of antifactor Xa (FXa) activity and plasma protein binding were also performed. Both ATH-coated and heparin-coated catheters demonstrated functional binding of exogenous AT. However, the ATH-coated catheters gave a trend towards elevated anti- FXa activities/AT binding ratios, consistent with the higher active pentasaccharide content in starting ATH. Western blot analysis of proteins adsorbed to catheters after incubation with rabbit plasma established protein binding profiles that showed AT and albumin as major plasma proteins adsorbed to ATH-coated catheters, while AT and altered forms of fibrinogen were major plasma protein species adsorbed to heparinized catheters.

Chronic performance of polyurethane catheters covalently coated with ATH complex: a rabbit jugular vein model.

Covalent complexes of antithrombin (AT) and heparin (ATH) have superb anticoagulant activity towards thrombin and factor Xa. Stability of polyurethane central venous catheters covalently modified with radiolabeled ATH was studied using a roller pump with saline or protease P-5147. Saline wash removed loosely bound ATH molecules to decrease graft density from 26 to 12 pmol/cm2. However, only slightly more ATH was removed by strong protease (from 12 to 7 pmol/cm2). To evaluate ATH-coated, heparin-coated, and uncoated catheters, a chronic rabbit jugular vein model was developed with catheters maintained for up to 30-106 days. Lumen occlusion was tested by drawing blood twice daily. Although unmodified or heparin-coated catheters occluded within 5-7 days after insertion, all ATH catheters remained patent throughout the experiment. Scanning electron microscopy (SEM) analysis of heparin and uncoated catheters revealed extensive thrombosis (lumen+mural) while ATH catheters were unaffected. Visual observation showed significant deposition of protein and cells on control and heparin-modified catheters and, to a lesser degree, on ATH-coated surfaces. SEM showed no fibrin inside or outside of ATH catheters, which remained patent in extended studies out to 106 days. Although atomic force microscopy showed ATH coatings to be rough, 6-fold higher anti-factor Xa activity likely contributed to increased patency. Our data confirm that ATH-modified catheters are stable and have superior potency compared to heparin or control catheters.

In vivo rabbit acute model tests of polyurethane catheters coated with a novel antithrombin-heparin covalent complex.

Catheter use has been associated with an increased risk of thrombotic complications. The objective was to make catheters less thrombogenic with the use of antithrombin-heparin covalent complex (ATH). The antithrombotic activity of ATH-coated catheters was compared to uncoated (control) and heparincoated catheters in an acute rabbit model of accelerated occluding clot formation. Anaesthetized rabbits were pre-injected with rabbit (125)I-fibrinogen, followed by insertion of test catheters into the jugular vein. Blood was drawn and held in a syringe, reinjected, then flushed with saline. The experiment was terminated when blood could no longer be withdrawn (occluding clot). Efficacy was defined as the ability of catheters to remain unoccluded. Clot formation, determined by measuring deposition of radiolabeled fibrin, was a secondary endpoint. ATH-coated catheters were resistant to clotting for the full 240-minute duration, while uncoated and heparin-coated catheters had an average clotting time of 78 and 56 minutes, respectively. The patency of ATH coating was dependant on intact heparin pentasaccharide sequences, rather than the chemistries of the basecoat, the PEO spacer arm, or the antithrombin (AT) protein. The ATH coating was stable to ethylene oxide sterilization, modest abrasion, protease attack, and the coating did not appear to leach off the catheter. Surface tension measurements showed that the ATH modified surface was more hydrophilic than uncoated control catheters or heparin-coated catheters. Thus, ATH-coated catheters are better at preventing clots than uncoated or heparin-coated catheters and show promise as an alternative to the currently available catheters in reducing thrombotic complications associated with its use.