黄土高原主要造林树种对鼢鼠危害的抗性研究

采用定植3 a林木的被害率和被害存活率指标,将黄土高原主要造林树种分为高抗、中抗、低抗和易害树种。油松、侧柏、山杏、刺槐和沙棘个体死亡时根系的被害程度依次为13.58%、19.81%、33.50%、39.62%、42.16%,被害林木死亡率为100%时的根系被害程度依次为72.52%、78.03%、81.25%、89.12%、90.14%。林木抗鼠性差异的主要原因是林木的生长特性和鼢鼠对其喜食的程度与取食量。林木根系生长愈快、萌生能力愈强,被害程度愈低,耐鼠性愈强。

Isolation of Ca^(2+) Tolerant Cardiomyocytes from Aadult Rats for Patch Clamp Studies

Objective: To investigate the factors affecting the viability and Ca 2+ tolerance of isolated rats' cardiac myocytes for patch clamp research. Methods: Hearts were firstly perfused by the Langendorff perfusion apparatus with normal Tyrode's solution, then with Ca 2+-free Tyrode's solution and subsequently with low Ca 2+ enzyme solution containing collagenase 0.1-0.2 g/L. All the solutions were saturated with oxygen and the perfusion temperature was kept at 37 ℃. Finally hearts were washed by Ca 2+-free Tyrode's solution, after which the ventricles were minced into small pieces in KB solution, dispersed and filtered. The isolated myocytes were stored in KB solution at room temperature for 1 h and recovered to normal calcium concentration before patch clamp experiments.Results: When all the factors such as water, enzyme, Ca 2+,pH, and oxygen were well controlled, the well constructed and rod-like cardiac myocytes with a yielding rate of 30%-50% came out.Conclusion: All the factors should be well controlled, which ensured the isolated cells Ca 2+ tolerant and appropriate for patch clamp experiments.

Nude mice multi-drug resistance model of orthotopic transplantation of liver neoplasm and Tc-99m MIBI SPECT on p-glycoprotein

AIM: To establish a model of drug-resistant neoplasms using a nude mice model, orthotopic transplantation of liver neoplasm and sporadic abdominal chemotherapy. METHODS: Hepatocellular carcinoma cells HepG2 were cultured and injected subdermally to form the tumor-supplying mice. The orthotopic drug-resistant tumors were formed by implanting the tumor bits under the envelope of the mice liver and induced by abdominal chemotherapy with Pharmorubicin. Physical examination, ultrasonography, spiral CT and visual inspection were used to examine tumor progression. RT-PCR and immunohistochemistry were used to detect expression of mdr1 mRNA and its encoded protein p-glycoprotein (p-gp). Tc-99m sestamibi scintigraphy was performed by obtaining planar abdominal images at 20 min after injection, and the liver/heart ratios were calculated. RESULTS: Post-implantation mortality was 0% (0/25), tumor implantation success was 90% (22/25), and the rate of implanting successfully for the second time was 100% (3/3). Tumor induction using Pharmorubicin was 80% (16/20). The mdrl mRNA expression of the induced group was 23 times higher than that of the control group, and p-gp protein expression was 13-fold higher compared to the control group. The liver/heart ratio (as assessed in vivo, using Tc-99m radiography) was decreased significantly in the induced group as compared to the control group. CONCLUSION: We have established an in vivo model of mdrl in nude mice by orthotopic transplantation of liver neoplasm coupled to chemotherapy. We propose that identification of drug resistance as characterized by decreased 99mTc-ppm radiography due to enhanced clearance by p-gp may be useful in detecting in vivo drug resistance, as well as a useful tool in designing more effective therapies.

Total body irradiation of donors can alter the course of tolerance and induce acute rejection in a spontaneous tolerance rat liver transplantation model

Liver transplantation is an established therapy for end-stage liver diseases. Graft rejection occurs unless the recipient receives immunosuppression after transplantation. This study aimed to explore the mechanism of acute rejection of liver allografts in rats pre-treated with total body irradiation to eliminate passenger lymphocytes and to define the role of CD4＋CD25＋ regulatory T cells in the induction of immunotolerance in the recipient. Male Lewis rats were used as donors and male DA rats were re- cipients. Rats were randomly assigned to the following four groups： control group, homogeneity liver transplantation group, idio-immunotolerance group and acute rejection group. After transplantation, the survival time of each group, serum alanine aminotransferase, total bilirubin levels, number of Foxp3＋CD4＋CD25＋ regulatory T cells, expression of glucocorticoid-induced tumor necrosis factor receptor on T cell subgroups, histopathology of the hepatic graft and spleen cytotoxic T lymphocyte lytic activity were measured. In the acute rejection group, where donors were preconditioned with total body in＇adiation before liver transplantation, all recipients died between day 17 and day 21. On day 14, serum alanine aminotransferase increased signifi- cantly to （459.2±76.9） U L^- 1, total bilirubin increased to （124.1±33.7） μmol L-1 （P〈0.05） and the ratio of Foxp3＋CD4＋CD25＋ regulatory T cells decreased significantly to 1.50%±0.50% （P〈0.05） compared with the other groups. Analysis of the T cell subpopulations in the acute rejection group varied from the other groups. Histological analysis showed typical changes of acute rejection in the acute rejection group only. Preconditioning of the donors with total body irradiation eliminated passenger lymphocytes of the liver graft, and thus affected the course of tolerance and induced acute rejection after liver transplantation.