pH modulates conducting and gating behaviour of single calcium release channels

Intracellular pH changes affect excitation-contraction coupling in skeletal, and cardiac muscles. However the proton implication in modulating the sarcoplasmic reticulum Ca²⁺ release channel activity has never been visualized at single channel level. A large conducting Ca²⁺ release pathway has previously been characterized after incorporation of skeletal and cardiac sarcoplasmic reticulum vesicles into planar lipid bilayers. This channel has been activated by micromolar and millimolar concentrations of Ca²⁺ and ATP, respectively. The pH was independently varied on each side of the channels. Acidification of the cis-chamber (7.4 to 6.6) induced a modification of the gating behaviour, resulting in a decrease of the open probability. This effect was completely reversible. On the other hand, acidification of the trans-chamber (7.4 to 6.8) induced a reduction of the unitary conductance of the sarcoplasmic reticulum Ca²⁺ release channel.     

Circadian and age-related modulation of thermoreception and temperature regulation: mechanisms and functional implications

At older ages, the circadian rhythm of body temperature shows a decreased amplitude, an advanced phase, and decreased stability. The present review evaluates to what extent these changes may result from age-related deficiencies at several levels of the thermoregulatory system, including thermoreception, thermogenesis and conservation, heat loss, and central regulation. Whereas some changes are related to the aging process per se, others appear to be secondary to other factors, for which the risk increases with aging, notably a decreased level of fitness and physical activity. Moreover, functional implications of the body temperature rhythm are discussed. For example, the relation between circadian rhythm and thermoregulation has hardly been investigated, while evidence showed that sleep quality is dependent on both aspects. It is proposed that the circadian rhythm in temperature in homeotherms should not be regarded as a leftover of ectothermy in early evolution, but appears to be of functional significance for physiology from the level of molecules to cognition. A new view on the functional significance of the circadian rhythm in peripheral vasodilation and the consequent out-of-phase rhythms in skin and core temperature is presented. It is unlikely that the strong, daily occurring, peripheral vasodilation primarily represents heat loss in response to a lowering of set point, since behavioral measures are simultaneously taken in order to prevent heat loss. Several indications rather point towards a supportive role in immunological host defense mechanisms. Given the functional significance of the temperature rhythm, research should focus on the feasibility and effectiveness of methods that can in principle be applied in order to enhance the weakened circadian temperature rhythm in the elderly.     

壳聚糖纳米颗粒包裹对鼠白细胞介素2基因表达和调节小鼠免疫效应的影响

本实验制备壳聚糖纳米颗粒 (CNP) ,包裹小鼠白细胞介素 2基因 (mIL 2 )真核表达质粒 (VRMIL 2 ) ,肌注接种 2 1d昆明小鼠 ,观察mIL 2基因体内表达及其对免疫应答和免疫保护的影响。实验结果发现 :CNP包裹VRMIL 2注射小鼠血液中IgG、IgM和IgA不同程度地增多 ,均显著高于CNP包裹空白质粒组 (P <0 .0 5 ) ;其血清中IL 2、IL 4和IL 6的含量明显升高 ,与对照组差异显著 (P <0 .0 5 ) ;外周血液的白细胞和淋巴细胞数量也较对照组显著增加。免疫后 35d以大肠杆菌口服攻毒实验小鼠 ,检测发现 :CNP包裹VRMIL 2组小鼠的上述免疫指标除中性粒细胞外均显著多于对照小鼠 ,VRMIL 2接种小鼠均健康存活 ,而对照小鼠均发病 ;尽管CNP包裹VRMIL 2接种小鼠的体液和细胞免疫指标与未包裹VRMIL 2免疫鼠差异不显著 (P >0 .0 5 ) ,但剂量仅为后者的 1/ 5。这些结果表明 :壳聚糖纳米颗粒包裹VRMIL 2可显著提高外源IL 2基因体内表达水平 ,明显增强体液和细胞免疫水平的效应 ,增强对大肠杆菌的抗病力 ,提示壳聚糖纳米颗粒包裹IL 2基因可明显增强动物的体液和细胞免疫 ,可作为有效的抗感染免疫调节剂。     

rIL-18对肺炎链球菌肺炎小鼠Th1/Th2免疫应答的影响

目的 研究重组白细胞介素18(rIL-18)对肺炎链球菌肺炎小鼠Th1/ Th2免疫应答的影响.方法 鼻腔接种肺炎链球菌建立小鼠肺炎链球菌肺炎模型,将Balb/c小鼠24只随机分为3组,分别为对照组,肺炎组和肺炎rIL-18干预组(n=8 ),RT-PCR法检测各组小鼠肺组织中IFN-γ、IL-4 mRNA 的表达,同时支气管肺泡灌洗液(BALB)进行活菌计数,有核细胞分类计数.结果 ①肺炎rIL-18干预组BA LF中性粒细胞和巨噬细胞计数显著高于肺炎组和对照组(P＜0.001);②肺炎rIL-18 干预组BALF活菌计数显著低于肺炎组(P＜0.001);③肺炎rIL-18干预组肺组织IFN- γ mRNA表达上调而IL-4 mRNA表达下调(P＜0.001).结论 在小鼠肺炎链球菌肺炎早期给予rIL-18可诱导IFN-γ的合成,促进Th1免疫应答,使Th1/ Th2免疫平衡向Th1免疫偏移、促进宿主对肺炎链球菌的防御.     

Construction of the Eukaryotic Expression Vector for Outer Membrane Protein Tp92 from Treponema pallidum and Its Preliminary Study on the Immune Responses in New Zealand Rabbits

Treponema pallidum subsp. pallidum is the causative a gents of syphilis. Presently, the annual infection rate ofdomestic and international syphilis remains rather high [1,2]. Apart from the serious nature of the disease itself, anumber of studies sugg…     

Neutrophil-mediated cellular cytotoxicity triggered by immobilized aggregated IgG: Anin vitro model of cell injury during immune complex diseases

Normal human neutrophils were found to destroy ox red blood-cell targets when incubated on micropore filters coated with aggregated IgG, as determined by the⁵¹Cr release method. An intact neutrophil oxidative metabolism was essential for the cytotoxic event, since cells from patients with chronic granulomatous disease failed to exert any cytolysis. The target-cell destruction was prevented by catalase, azide, and cyanide and was enhanced by superoxide dismutase, suggesting involvement of the myeloperoxidase-hydrogen peroxide system. Neutrophil-mediated cytotoxicity was markedly amplified by the chemotactic peptideN-formyl-methionyl-leucylphenylalanine, as a result of an increased activity of the myeloperoxidase-hydrogen peroxide cytolytic system itself. This system of cytotoxicity provides a direct evidence for the neutrophil capacity of destroying bystander target cells under conditions simulating thein vivo immunologically mediated tissue injury and offers an excellent model to study events occurring during immune complex diseases.Supported by Grant 83.00902.96/115.11547 from the Italian CNR-PFCCN.     

C3 binds with similar efficiency to Fab and Fc regions of IgG immune aggregates

The covalent binding reaction of the third component of complement (C3) with rabbit IgG immune aggregates has been studied by enzymic digestion of C3b-IgG adducts. In these adducts C3b was radioactively labeled in the free thiol group generated during activation of the internal thioester of C3. Trypsin digestion of ¹⁴C-labeled C3b-IgG adducts degrades C3b to a small antibody-bound ¹⁴C-labeled C3 fragment (¹⁴C-C3frg), whereas the antibody remains unaltered. Papain digestion of trypsin-treated ¹⁴C-C3frg-IgG complexes generated Fc and Fab fragments bearing equivalent amounts of covalently bound ¹⁴C-C3frg (43% and 40%, of the total C3 present in the aggregates, respectively). Hydroxylamine treatment of the ¹⁴C-C3frg-Fab and ¹⁴C-C3frg-Fc complexes released a ¹⁴C-C3frg of similar size (about 3–4 kDa) in which the N-terminal residue was the radiolabeled Cys¹⁰¹⁰. A fragment with the same radioactive N terminus and characteristics was obtained by sequential trypsin and papain digestion of purified C3 labeled with iodo–[¹⁴C] acetamide. Affinity-purified ¹⁴C-C3frg-Fc complexes digested with pepsin generated a mixture of radioactive peptides, most probably complexes formed by ¹⁴C-C3frg and Cγ2 or the hinge digestion products, and ¹⁴C-C3frg-pFc' complexes. The latter was also immunoprecipitated with anti-Fc-Sepharose from the pepsin digestion supernatants of ¹⁴C-labeled-C3b-IgG complexes. Taken together these data indicate that, during complement activation through the alternative pathway by IgG immune aggregates, C3 is not bound to a single site on the antibody molecule. Both Fab and Fc regions of IgG are equally efficient targets for C3 anchorage. In addition, the data confirm the pFc' as a region of C3 attachment within the Fc portion, and strongly suggest that C3b is bound either to the Cγ2 domain or the hinge or both.     

Maternal immunization modulates the primary immune response to 2-phenyl-oxazolone in BALB/c mice

The development of the antibody repertoire in newborn mice is greatly influenced by idiotypic network interactions. It has been demonstrated that anti-idiotypic antibodies either directly injected or transferred from the mother may alter the repertoire for life. For an elucidation of the underlying mechanisms we have analyzed the primary immune response to 2-phenyl-5-oxazolone (phOx) coupled to chicken serum albumin (CSA) in BALB/c mice after complete disappearance of maternal antibodies which originated from different stages of affinity maturation. Depending on the serum titers of the mothers after primary (1° mo), secondary (2° mo) or tertiary (3° mo) immunization, maternal anti-phOx IgG persisted in F1 mice for up to 9 months. In addition, F1 mice born to 2° mo developed – even without immunization – an anti-phOx IgM titer which reached levels similar to an antigen-induced primary response. An enhancement of the early primary anti-phOx as well as anti-CSA response was seen in F1 mice born from 1° mo, whereas the response was delayed when born to 2° mo and 3° mo. The antibody titers in the latter group of mice remained at a lower level for 3 months. In contrast, mice of the F2 generation which received a smaller amount of the same collection of maternal antibodies as F1 mice from 3° mo exhibited a quite different primary response: (i) They showed an earlier onset in their anti-CSA response. (ii) Whereas normally a plateau in antibody titer was reached by the 4th weak after immunization, in 55 % of the F2 mice a prolonged increase of the anti-phOx and anti-CSA antibody titers was observed. At 12 weeks after antigenic challenge, titers reached plateau levels of 6 × 10⁵ which were never before seen in a primary phOx or CSA response. Thus, depending on its own immunological experience, the maternal immune system induces a state of memory in the offspring which results in a faster and/or enhanced immune response in the F1 and F3 generations.     

T-bet重组腺病毒对哮喘小鼠Thl/Th2免疫平衡的调节

目的探讨静脉应用T-bet重组腺病毒（AdT-bet）对哮喘模型小鼠过敏性气道炎症及Th1／Th2免疫失衡的影响。方法36只C57BL/6小鼠随机分为AdT-bet治疗组（A组）、模型对照组（B组）、正常组（C组）。以卵蛋白（OVA）、氢氧化铝免疫建立哮喘模型，A组激发前尾静脉注射100μL的AdT-bet（1×10^8 PFU/μL），各组激发后肺泡灌洗分析细胞组份，分离肺淋巴细胞测定细胞因子分泌水平，以流式细胞仪检测CD3^＋、CD4^＋ T细胞比例及表达IFNγ和IL-4的比例，比较各组肺组织学改变。结果静脉应用AdT-bet组与对照组相比：①可明显抑制抗原激发后气道内嗜酸性粒细胞的浸润（P〈0．01）；②明显抑制肺淋巴细胞产生IL-4、IL-5，增加了IFNγ的产生；③肺脏淋巴细胞CD4^＋ IFNγ百分比及IFNγ^＋/IL-4^＋明显升高（P〈0．01），而CD4^＋ IL-4^＋百分比则明显下降；④明显抑制哮喘鼠气道内及肺泡内的过敏性炎症反应。结论激发前静脉用AdT-bet对哮喘小鼠过敏性气道炎症有明显的防治作用，其机制可能与表达的T-bet上调Th1／Th2比值，从而调整了免疫平衡有关。     

Immunobiology of lnterleukin-12

Interleukin-12 (IL12) is a heterodimeric cytokine which is produced by phagocytic cells and antigen-presenting cells within a few hours of infection, particularly in the case of bacteria and intracellular parasites, and acts as a proinflammatory cytokine, activating natural killer (NK) cells, and, through its ability to induce interferon-γ (IFNγ) production, enhancing the phagocytic and bacteriocidal activity of phagocytic cells and their ability to release proinflammatory cytokines, including IL12 itself. Furthermore, IL12 produced during the early phases of infection and inflammation, sets the stage for the ensuing antigen-specific immune response, favoring differentiation and function of T helper type 1 (Th1) T cells while inhibiting the differentiation of Th2 T cells. Thus, IL12, in addition to being a potent proinflammatory cytokine, is a key immunoregulator molecule in Th1 responses.