Intranasal treatment with ovalbumin but not the major T cell epitope ovalbumin 323–339 generates interleukin-10 secreting T cells and results in the induction of allergen systemic tolerance

BACKGROUND: Nasal administration of major peptide T cell epitopes gives contradictory data on the induction of peripheral tolerance. OBJECTIVE: To compare the prophylactic effect of intranasal treatment (INT) on the development of an allergic response, using either ovalbumin (OVA) or its major T cell epitope OVA 323-339 (OVAp). METHODS: BALB/c mice were treated intranasally with OVA or OVAp and subsequently immunized s.c. with OVA. Anti-OVA-specific antibody, T cell proliferation and cytokine responses were analysed. In an adoptive transfer model using OVAp specific TCR transgenic (Tg) T cells from D011.10 mice, in vivo tracking and characterization of transferred T cells in the cervical, inguinal and bronchial lymph nodes (BLN) and in the spleen were determined by FACS analysis. RESULTS: Prophylactic INT with OVA induced T cell tolerance towards subsequent OVA s.c. immunizations, inhibiting OVA specific T cell proliferation, IgE and IgG1 production, in contrast to INT with OVAp, which was unable to induce tolerance. In vivo analysis of transferred OVA-specific TCR Tg T cells showed that INT with OVA induced a preferential activation of T cells in BLN, as opposed to a broad, systemic activation with OVAp. In vivo, OVAp INT led to faster and more sustained cell division cycles than OVA INT. Ex vivo, tolerance to OVA was associated with the generation of IL-10 secreting CD4(+) T cells in BLN of OVA-treated mice only. CONCLUSION: INT with OVA but not with OVAp led to regional (as opposed to systemic) T cell activation and the induction of IL-10 secreting CD4(+) T cells in BLN, potentially critical steps in the induction of T cell-specific tolerance via the nasal route.     

TIA对后继脑梗死神经保护作用的临床研究

目的探讨预先短暂性脑缺血发作(TIA)是否对后继脑梗死具有神经保护作用。方法根据脑梗死患者是否预先发生同侧的TIA分为TIA组和无TIA组,分别从TIA持续时间、发作次数、与脑梗死间隔时间及梗死部位几方面同无TIA组比较,采用ADL评分标准,评定患者预后恢复情况。结果Ⅰ级预后预先有TIA的占72%,无TIA的占63%,二者相比差异无显著性(X~2=3．31,P＞0．05)。但脑梗死前有TIA且持续时间在5～20min、发作次数2～3次,与脑梗死间隔不超过1周者,其Ⅰ级预后较多,同无TIA组相比较差异有显著性(P＜0．05)。结论脑梗死前发生的TIA有可能对人脑产生缺血耐受作用。TIA的神经保护性与其发作持续时间、发作次数及与脑梗死间隔时间有一定关系。     

具有靶向免疫抑制作用新型重组融合蛋白B7-2-PE40KDEL真核表达载体的构建及其生物效应

目的:构建B7-2-PE40KDEL的真核表达载体,探讨通过体内表达重组融合蛋白,特异性杀伤高表达CD28 T细胞,阻断B7∶CD28/CTLA4共刺激信号途径诱导免疫耐受的可能性.方法:以原核表达载体pRSETA-B7-2-PE40KDEL质粒为模板,采用PCR及酶切连接的方法构建真核表达载体pcDNA3.1/Zeo( )-B7-2-PE40KDEL.利用RT-PCR、Western 印迹及ELISA法从mRNA、蛋白质水平检测了B7-2-PE40KDEL在RPE-CHO真核细胞中的表达情况.采用MTT法对其特异性杀伤高表达CD28 T细胞的生物活性进行测定.结果:成功构建了pcDNA3.1/Zeo( )-B7-2-PE40KDEL真核表达载体,转染入RPE-CHO细胞后可转录翻译为重组融合毒素蛋白,相对分子质量约为71×103,平均106个转染细胞24 h表达0.23 μg/L.活性测定显示真核载体所表达的B7-2-PE40KDEL可特异性地抑制高表达CD28的人T淋巴细胞系,而对CD28阴性的人白血病细胞系的抑制率较低.结论:真核载体表达的B7-2-PE40KDEL具有良好的靶向性免疫抑制活性,为进一步开展其体内特异性防治移植排斥反应及自身免疫性疾病奠定了基础.     

Epicutaneous exposure to peanut protein prevents oral tolerance and enhances allergic sensitization

BACKGROUND: Food allergies are an important cause of life-threatening hypersensitivity reactions. Oral tolerance can be considered the default immune response to dietary antigens, with immune deviation resulting in allergic sensitization. However, primary sensitization to food allergens may not solely be through the gastrointestinal mucosa, as strong T-helper type 2 (Th2)-biased immunity can result from exposure to protein allergens on barrier-disrupted skin. OBJECTIVE: The purpose of this study was to examine whether exposure to allergens through the skin may interfere with the normal development of oral tolerance and promote allergic sensitization to food proteins. METHODS: Female BALB/c mice were exposed epicutaneously to peanut protein and induction of systemic oral tolerance through high dose feeds of peanut protein was subsequently assessed. Other mice were rendered tolerant prior to epicutaneous peanut exposure. Sensitivity to peanut was determined by assessing delayed-type hypersensitivity, proliferative, cytokine and antibody responses. RESULTS: Epicutaneous exposure to peanut protein induced potent Th2-type immunity with high levels of IL-4 and serum IgE. Primary skin exposure prevented the subsequent induction of oral tolerance to peanut in an antigen-specific manner. Upon oral challenge, mice became further sensitized and developed strong peanut-specific IL-4 and IgE responses. Furthermore, animals with existing tolerance to peanut were partly sensitized following epicutaneous exposure. CONCLUSION: Epicutaneous exposure to peanut protein can prevent induction of oral tolerance, and may even modify existing tolerance to peanut. Epidermal exposure to protein allergens selectively drives Th2-type responses, and as such may promote sensitization to food proteins upon gastrointestinal exposure.     

Mechanisms of Tolerance Induced by Donor-Specific Transfusion and ICOS-B7h Blockade in a Model of CD4+ T-Cell-Mediated Allograft Rejection

The inducible co-stimulatory molecule (ICOS) has been shown to play a critical role in T-cell activation and differentiation, and the regulation of alloimmune responses in vivo. Using an MHC class II mismatched model of CD4(+) T-cell-mediated rejection, we found that treatment of mice with DST and ICOS-B7h blockade induced long-term skin allograft survival and donor-specific transplantation tolerance. ICOS blockade, either during antigen priming or during the effector phase, previously shown to alter the outcome of the immune response, had a similar effect on graft survival. DST and anti-B7h mAb reduced the frequency of IFN-gamma-producing allospecific cells but did not produce deviation to a T(H)2 phenotype. In an adoptive transfer model using ABM TCR transgenic mice directly reactive to I-A(bm12), DST and anti-B7h mAb reduced the number of allospecific CD4(+) T cells and increased CD4(+) T-cell apoptosis. These data demonstrate that DST and anti-B7h mAb induces transplantation tolerance to MHC class II mismatched skin grafts by a reduction of the alloreactive clone size that is, at least in part, dependent on apoptosis of host alloantigen-specific CD4(+) T cells.     

供者特异性抗原静脉输注联合抗γ链单克隆抗体诱导小鼠皮肤移植物免疫耐受

目的　探讨静脉输注供者特异性抗原联合抗白细胞介素2受体(IL 2R)γ链单克隆抗体诱导移植免疫耐受的可行性。方法　在C57BL/6小鼠建立H Y皮肤移植模型,术前7 d给予5×106个供者脾细胞静脉输注,并分别于术前6 d和4 d给予抗白细胞介素2受体γ链单克隆抗体(4G3、3E12及TUGm2各0.5 mg)和抗IL 2Rβ单克隆抗体(TM β1,0.5 mg)混合液2.0 mg腹腔注射,以单纯行H Y皮肤移植模型和静脉输注供者特异性抗原的H Y皮肤移植模型为对照,观察皮肤移植物的存活时间。结果　联合给予抗白细胞介素2受体γ链单克隆抗体和供者特异性抗原输注组的皮肤移植物存活时间均超过100 d,显著长于单纯H Y皮肤移植组的33.42 d(P<0.01)及仅输注供者特异性抗原H Y皮肤移植组的14.71 d(P<0.01)。结论　在H Y皮肤移植模型中,静脉输注供者特异性抗原联合抗白细胞介素2受体γ链单克隆抗体可以成功地诱导受者对皮肤移植物的免疫耐受。     

Some behavioral effects of repeated d-amphetamine administrations

Effects of daily administrations of d-amphetamine were studied on key peck responses of pigeons maintained under a multiple fixed-interval 2-min, fixed-ratio 30-responseschedule. Under the fixed-interval schedule, a pause was followed by a transition to increasing rates of responding until food presentation. Under the fixed-ratio schedule, higher sustained rates of responding were maintained. Low to intermediate doses (0.3-1.0 mg/kg) of d-amphetamine changed the temporal patterns and occasionally increased rates of responding under the fixed-interval schedule. Higher doses decreased rates of responding under bothschedules. With daily injections of 1.0 mg/kg d-amphetamine prior to experimental sessions, the effects of this dose on rates and patterns of responding were attenuated, and d-anphetamine dose-effect curves were shifted to the right, primarily under the fixed-ratio schedule. Similar results were obtained with daily presession injections of 5.6 mg/kg d-amphetamine in a second group of pigeons, except that rates of responding under both schedules were decreased by this daily dose, and did not return completely to control values with repeated injections. In a third group of pigeons, 1.0 mg/kg d-amphetamine administered daily, after experimental sessions, did not alter dose-effect functions for d-amphetamine. In a second experiment, pigeons were trained to peck one response key when given 1.0 mg/kg d-amphetamine and a different key when given presession water injections. Increasing doses of d-amphetamine produced incresing percentages of d-amphetamine-key responses. Repeated administration of 5.6 mg/kg d-amphetamine shifted these dose-effect functions to the right one-half log unit. Results suggested that decreases in reinforcement frequency are not a necessary condition for the development of behavioral tolerance to d-amphetamine.     

Progressive peri‐implantitis. Incidence and prediction of peri‐implant attachment loss.

The aim of this prospective study was to characterize an implant patient population exhibiting clinical signs of peri‐implantitis and to determine subsequently the incidence of progressive attachment loss. The predictive values of diagnostic parameters were evaluated. 25 patients with 54 endosseous implants that had been loaded for 41±15 months were included in the study. Clinical parameters included the assessment of plaque, bleeding on probing, probing depth, attachment levels, and Periotest® values. Probing measurements were performed in duplicate by means of a controlled force electronic probe (Periprobem). Peri‐implant crevicular fluid samples were collected and assayed for neutral proteolytic enzyme (NPE) activity (Periocheck®). Analysis of duplicate baseline probing data revealed a high degree of reproducibility (mean difference: 0.1±0.3mm). A minimum threshold of 1.0mm (>3×S.D.) loss of probing attachment was chosen to classify a site as positive for breakdown. Alternatively, the tolerance method was employed to identify sites with progressive attachment loss. After 6 months, irrespective of the analytical method, 6 percent of all sites (in 19% of the implants) and 28% of the patients had experienced further per attachment loss. There were significant differences ( p <0.05) in mean plaque (73% vs. 45%) and NPE (36% vs. 12%) scores between patients with progressive peri‐implantitis and those with stable peri‐implant conditions. Both bleeding on probing and the NPE‐test were characterized by high negative predictive values, and thus negative scores can serve as indicators for stable peri‐implant conditions. For monitoring peri‐implant health during recall visits, attachment level recordings with a controlled force electronic probe in conjunction with enzymatic diagnostic tests of the host response can be recommended.     

高性能战斗机飞行员离心机高G训练方案

目的制定我国高性能战斗机飞行员离心机高Ｇ训练方案。方法拟定离心机高Ｇ训练方案，对４７名飞行员进行训练，训练后检验训练效果，提出训练方案。结果训练后受试者采用综合抗荷措施时的Ｇ耐力比基础Ｇ耐力高４．３Ｇ～４．７Ｇ，比训练前提高了１．９Ｇ～３．３Ｇ（Ｐ＜０．０１）。结论按本研究提出的高Ｇ训练方案进行训练，可显著提高飞行员的Ｇ耐力，该训练方案有效可行。     

Induction of NADPH-diaphorase activity in the hippocampus in a rat model of cerebral ischemia and ischemic tolerance

Preconditioning of the brain with sublethal ischemia induces tolerance to subsequent lethal periods of ischemia (ischemic tolerance). In this study, we used NADPH-diaphorase histochemistry to investigate the postischemic changes of nitric oxide synthase (NOS) in the hippocampus in a rat model of cerebral ischemia and ischemic tolerance. Forebrain ischemia was induced by 4-vessel occlusion for 3 min as an ischemic preconditioning. Three days after the preconditioning or sham operation, second ischemia was induced for 6 min. A transient increase in NADPH-diaphorase activity, beginning after 2 h and maximal after 1 day, was observed in CA1 pyramidal neurons of rats subjected to 3 min of preconditioning ischemia as well as 6 min of subsequent ischemia both with and without preconditioning. In addition, expression of NADPH-diaphorase activity was seen in reactive glial cells in the damaged CA1 region of animals subjected to 6 min of ischemia without preconditioning. Thus, direct involvement of increased NADPH-diaphorase activity in ischemic tolerance was not suggested because the increased NADPH-diaphorase activity preceded the induction of ischemic tolerance which takes place 1–7 days after preconditioning. However, the present findings suggest that the induction of neuronal NADPH-diaphorase activity occurs in response to cerebral ischemia.