Molecular Cloning of the cDNA Encoding pp36, a Tyrosine-phosphorylated Adaptor Protein Selectively Expressed by T Cells and Natural Killer Cells

Activation of T and natural killer (NK) cells leads to the tyrosine phosphorylation of pp36 and to its association with several signaling molecules, including phospholipase Cγ-1 and Grb2. Microsequencing of peptides derived from purified rat pp36 protein led to the cloning, in rat and man, of cDNA encoding a T- and NK cell–specific protein with several putative Src homology 2 domain–binding motifs. A rabbit antiserum directed against a peptide sequence from the cloned rat molecule recognized tyrosine phosphorylated pp36 from pervanadate-treated rat thymocytes. When expressed in 293T human fibroblast cells and tyrosine-phosphorylated, pp36 associated with phospholipase Cγ-1 and Grb2. Studies with GST–Grb2 fusion proteins demonstrated that the association was specific for the Src homology 2 domain of Grb-2. Molecular cloning of the gene encoding pp36 should facilitate studies examining the role of this adaptor protein in proximal signaling events during T and NK cell activation.     

中频交变磁场照射后小鼠的行为学变化

目的:目前电磁辐射对生物体行为学方面的研究还很薄弱,设立不同磁场的强度和不同照射的周期,观察中频领域磁场照射对小鼠的自主活动和学习记忆的影响。方法:实验于2007-05-10/06-15在清华大学医学院和中国医学科学院药用植物研究所完成。①实验材料:磁场发生装置:中频交变磁场发生装置由清华大学工程物理系医学物理与工程研究所自主研发,可产生频率为40kHz,场强为28.8A/m,28.8kA/m的中频交变磁场。自主活动测试箱:中国医学科学院药用植物研究所提供,为一可封闭的金属箱,内置摄像头。4只黑色塑料测试桶分别置于箱子四角。水迷宫测试箱:中国医学科学院药用植物研究所提供。②实验动物及方法:将80只小鼠随机分为不同场强照射组和对照组。强磁场照射1组:11.6kA/m/40kHz,1h/d,连续照射7d。强磁场照射2组:11.6kA/m/40kHz,2h/d,连续照射7d。强磁场照射3组:11.6kA/m/40kHz,2h/d连续照射15d。弱磁场照射组:28.8kA/m/40kHz,2h/d,连续照射7d。对照组除了未放入磁场照射,其他条件与照射组一致。实验过程中对动物处置符合动物伦理学要求。③实验评估:观察其一般活动的改变,并采用自主活动测试箱和水迷宫测试箱进行测试,观察各组小鼠的自主活动和学习记忆的改变。结果:①一般行为观察:与对照组小鼠对比,经过中频交变磁场照射过的各组小鼠活跃度减低,毛色较差。强磁场照射3组(145G,2h/d,连续15d)于第11天和13天分别死亡1只。②自主活动检测结果:强磁场照射2,3组小鼠的运动路程、运动速度、运动时间明显低于对照组(P<0.05)。③水迷宫测试结果:在学习记忆检测阶段撤掉平台,发现各组动物2min内穿越平台原来所在象限的次数没有明显差别(P>0.05)。结论:中频交变磁场照射会给小鼠的自发活动造成一定影响,对学习记忆没有影响。     

口服糖皮质激素大鼠皮肤组织形态学变化

目的:观察口服糖皮质激素大鼠皮肤形态学改变,为建立新的皮肤衰老动物模型提供形态学上的依据。方法:实验于2006-07/2007-02在广东医学院药理教研室组织药理实验室完成。①实验对象:20只SD雄性SPF级大鼠随机分为两组,糖皮质激素组和空白对照组,每组10只。②实验方法:糖皮质激素组每天口服灌胃糖皮质激素3.5mg/(kg·d),空白对照组每天口服灌胃同等剂量生理盐水,喂养100d后麻醉下处死大鼠,取背部正中1cm×1cm大小皮肤组织检测相关指标。③实验评估:常规苏木精-伊红染色、VanGieson染色法、Weigert-间苯二酚-碱性品红染色法观察皮肤组织形态改变,并用计算机图像分析系统定量分析表皮厚度和弹力纤维总面积。结果:纳入结果分析16只,其中空白对照组8只,糖皮质激素组8只。糖皮质激素组大鼠皮肤表皮变薄,弹力纤维面积减少,胶原纤维多断裂,排列疏松,糖皮质激素组大鼠表皮厚度(33.8±3.1)μm,弹力纤维总面积(3557.9±373.1)μm2,均小于对照组大鼠表皮厚度(63.7±7.4)μm,弹力纤维总面积(5049.0±497.5)μm2。结论:糖皮质激素3.5mg/(kg·d)口服灌胃100d可导致大鼠皮肤衰老样改变,与人类皮肤衰老有相似形态学表现。     

Lazaroid U-83836E Improves Tolerance to Hemorrhagic Shock and Limb Ischemia and Reperfusion in Rats and Increases Cardiac Heat Shock Protein 72

Objectives: Aminosteroids of the lazaroid type protect organs from ischemia–reperfusion damage. The authors hypothesized that lazaroid U‐83836E may be beneficial in a shock model with hemorrhage combined with limb ischemia. Furthermore, the authors hypothesized that lazaroids induce expression of heat shock proteins (HSPs) of the 72‐kDa family. Methods: Rats were divided into two groups (lazaroid and control groups, n= 8 each) and pretreated with the lazaroid U‐83836E (5 mg/kg) or with vehicle intraperitoneally at 12 and 24 hours before experiments. At the time of the experiment, rats were anesthetized, and the femoral artery of each rat was cannulated. After 20 minutes of stabilization, blood was shed from each rat to bring its mean arterial pressure to 24–28 mmHg for 2 hours. Bilateral tourniquets were tightened proximally on the rat thighs during those 2 hours and then released. Shed blood plus equal amounts of Ringer acetate then were infused to restore normal blood pressure, followed by a continuous infusion of Ringer acetate, the rate of which was regulated to maintain blood pressure, until 30 minutes after start of resuscitation. Fluid resuscitation was stopped, and rats were observed for another 3.5 hours. At the end of the observation period, the rats' hearts were collected for immunoblot analysis of HSP72. Additional hearts were collected from similarly pretreated rats not undergoing the episode of hemorrhagic shock and fluid resuscitation. Results: Pretreatment with U‐83836E improved mean arterial blood pressure after hemorrhagic shock and fluid resuscitation (p = 0.02), combined with improvements in acid–base balance (improved base excess and standard bicarbonate; p = 0.02 and p = 0.01, respectively). Western blot of cardiac protein extracts demonstrated that lazaroid pretreatment increased expression of HSP72. Conclusions: Pretreatment with the lazaroid U‐83836E improved outcome markers in this hemorrhagic shock model. The observed protection may be caused by increased expression of HSP72.     

Opportunistic infections and organ‐specific diseases in HIV‐1‐infected children: a cohort study (1990–2006)

Objectives

Highly active antiretroviral therapy (HAART) has dramatically changed the natural history of HIV infection in children, but there are few studies in the literature about the incidence of clinical manifestations after HAART in this population, compared with adults. The aim of this study was to describe the influence of the widespread use of HAART on the development of opportunistic infections and organ‐specific diseases in HIV‐infected children.

Methods

An observational study of a cohort of 366 vertically HIV‐infected children followed from 1990 to 2006 was carried out. According to the main antiretroviral protocol used, three calendar periods (CPs) were defined and compared: CP1 (1990–1996: no patients on HAART), CP2 (1997–1999: <60% on HAART) and CP3 (2000–2006: >60% on HAART).

Results

Children experienced a progressive increase in CD4 T cell count (P<0.05) and a decrease in HIV viral load from 1996 onwards (P<0.05). Similarly, rates of death, AIDS, opportunistic infections (bacteraemia, candidosis, cryptosporidiosis and bacterial pneumonia) and organ‐specific diseases (wasting syndrome, thrombocytopenia, cardiomyopathy, lymphoid interstitial pneumonia and HIV‐associated encephalopathy) were lower in CP2 and CP3 than in CP1.

Conclusions

This study provides evidence of improved clinical outcomes in HIV‐infected children over time and shows that mortality, AIDS, opportunistic infections and organ‐specific diseases declined as HAART was progressively instituted in this population.

     

The rat NK cell receptors Ly49s4 and Ly49i4 recognize nonclassical MHC-I molecules on Listeria monocytogenes-infected macrophages

Ly49 receptors in rodents, like KIRs in humans, regulate NK cell activity. Although inhibitory Ly49 receptors clearly recognize MHC-I molecules, ligands for the activating Ly49 receptors are less well defined. Here, we show that the activating Ly49s4 and the inhibitory Ly49i4 receptors recognize nonclassical MHC-I molecules on the rat macrophage cell line R2 (RT1(d)). Listeria infection of R2 macrophages led to increased expression of classical and nonclassical MHC-I molecules. Coincubation of these infected cells with reporter cells expressing Ly49i4 or Ly49s4 increased the reporter cell responses. These responses were blocked by mAb OX18 (anti-MHC-I) and AAS1 (anti-nonclassical MHC-I). IFN-γ treatment of normal R2 cells also increased the MHC-I expression and enhanced the reporter cell responses. These results suggest that activating and inhibitory Ly49 receptors monitor MHC-I expression on Listeria-infected cells.     

A second prophylactic MHC-mismatched bone marrow transplantation protects against rat acute myeloid leukemia (BNML) without lethal graft-versus-host disease

BACKGROUND: We have employed a rat model for human acute myeloid leukemia, a promyelocytic leukemia in the BN rat strain (BNML), to develop new protocols for immunotherapy in combination with allogeneic bone marrow transplantation (alloBMT). The status of mixed chimerism in allotransplanted rats provided an opportunity for immunotherapy using alloreactive donor cells. In addition to T or natural killer (NK) cells, we introduced a second infusion of bone marrow cells as prophylactic donor lymphocyte infusions (DLI) to test whether an effective graft-versus-leukemia (GVL) response could be obtained without clinical graft-versus-host disease (GVHD). METHODS: BN rats were sublethally irradiated and transplanted with T-cell depleted bone marrow cells from either fully major histocompatibility complex (MHC)-mismatched (PVG) donor rats or MHC-matched (PVG.1N) as controls. Seven days after transplantation, rats were given 500 leukemic cells to mimic minimal residual disease. Additional cellular therapy was given at day +7. The efficiency of DLI was monitored by chimerism analysis in peripheral blood. RESULTS: Rats receiving infusions of NK cells succumbed to leukemia. T-DLI induced complete donor T-cell chimerism and lethal GVHD. A second alloBMT protected against leukemia. This effect was dependent on an MHC incompatibility between the donor and host and also on the presence of alloreactive T cells in the second bone marrow inoculum, resulting in an increased, mixed donor T-cell chimerism. CONCLUSION: A second prophylactic transplantation influenced the degree of T-cell chimerism to balance favorably between GVL and GVHD. If applicable to humans, repeated alloBMT may provide a novel approach to leukemia therapy.