Analysis of false negative results in the immunoassay for anti-acetylcholine receptor antibodies in myasthenia gravis

Possible causes for the failure of immunoassays to detect anti-acetylcholine receptor activity in serum from confirmed myasthenia gravis (MG) patients were investigated. A more sensitive assay, using Protein A to trap immune complexes (ARIA), was applied to 65 MG sera which were negative in the usual assay and to 42 normal human sera. Normal and negative MG sera had antibody (Ab) activity in the same range (50-70 pM). Titers present in 70% of normal sera appeared to be specific antireceptor antibodies as defined by tests for antigen specificity. Thus, higher sensitivity assays did not improve discrimination of MG from normals. In a second group of 108 MG sera studied, 48 were negative by the usual assay criteria in a rat acetylcholine receptor immunoassay. Further detailed analysis of this negative group showed that 3/48 had IgG3 antibody not detectable in the test, 14/48 had Ab's recognizing human receptor determinants exclusively, 29/48 had toxin blocking Ab's not determined by immunoassays, and 6/48 were negative in all tests. The results indicate that the exclusive occurrence of toxin-blocking antibodies in MG subjects is a major factor contributing to false negatives in the ARIA test. Estimates of the amount of Ab's with this functionality indicated that they are present in very much smaller amounts than other classes of anti-receptor Ab's. Degree of blocking activity in patient serum showed a fair correlation with severity of disease. Thus, blocking antibodies appear capable of causing all degrees of disease severity in the absence of other types of antireceptor Ab's. The development of a sensitive and quantitative in vitro assay for blocking antibodies combined with the usual immunoassay would be a major improvement for a MG diagnostic test, with greater than 94% positivity predicted.     

Pre-exposure of murine macrophages to lipopolysaccharide inhibits the induction of nitric oxide synthase and reduces leishmanicidal activity

Murine macrophages produce nitric oxide (NO) from L-arginine on stimulation with lipopolysaccharide (LPS), alone or with interferon-γ (IFN-γ). The effect of incubation of macrophages with low concentrations of LPS on NO synthesis on subsequent stimulation was investigated, using a murine macrophage cell line, J774, and peritoneal macrophages from CBA mice. Cells which had been incubated with LPS produced significantly lower amounts of NO, and expressed lower levels of NO synthase activity, following stimulation with IFN-γ and LPS, or with a high concentration of LPS. This effect was not reversed by tumor necrosis factor-α. The ability of CBA macrophages to kill the intracellular parasite Leishmania major was markedly reduced by pre-incubation with LPS. Reduced NO production by macrophages previously exposed to LPS is a manifestation of endotoxin tolerance, and may represent an important means of regulation of NO synthesis and thus a survival mechanism for intracellular parasites.     

A novel negative regulator for IL-1 receptor and Toll-like receptor 4

The Toll-IL-1 receptor (TIR) superfamily, defined by the presence of an intracellular TIR domain, initiates innate immunity via NF-kappaB activation, leading to production of proinflammatory cytokines. ST2 is a member of the TIR family that does not activate NF-kappaB and has been suggested as an important effector molecule of type 2 T helper cell responses. We have recently demonstrated that the membrane bound form of ST2 (ST2L) negatively regulated IL-1RI and TLR4 but not TLR3 signaling by sequestrating the adaptors MyD88 and Mal. In contrast to wild-type mice, ST2 deficient mice failed to develop endotoxin tolerance. Thus, ST2 suppresses IL-1R and TLR4 signaling via MyD88- and Mal-dependent pathways and modulates innate immunity. The results provide a molecular explanation for the role of ST2 in T(H)2 responses since inhibition of TLRs will promote a T(H)2 response and also identify ST2 as a key regulator of endotoxin tolerance.     

Mice lacking the norepinephrine transporter are supersensitive to psychostimulants

The action of norepinephrine (NE) is terminated, in part, by its uptake into presynaptic noradrenergic neurons by the plasma-membrane NE transporter (NET), which is a target for antidepressants and psychostimulants. Disruption of the NET gene in mice prolonged the clearance of NE and elevated extracellular levels of this catecholamine. In a classical test for antidepressant drugs, the NET-deficient (NET-/-) animals behaved like antidepressant-treated wild-type mice. Mutants were hyper-responsive to locomotor stimulation by cocaine or amphetamine. These responses were accompanied by dopamine D2/D3 receptor supersensitivity. Thus altering NET expression significantly modulates midbrain dopaminergic function, an effect that may be an important component of the actions of antidepressants and psychostimulants.     

Clinical and cytogenetics studies on acute myeloid leukemia with abnormality of chromosome 11

OBJECTIVE: To investigate the incidence of chromosome 11 abnormality in acute myeloid leukemia and its relationship with the clinical aspects and prognosis. METHODS:Conventional cytogenetic analysis of R-band was used to detect the abnormalities of chromosome 11 in 356 acute myeloid leukemia patients. RESULTS: Thirty-four out of 356 patients (9.55%) had abnormalities of chromosome 11, of which 20 (58.8%) involved in 11q23, 7 (19.9%) had translocations involving 11p15, 5 (14.7%) had-11, and the rest had other abnormalities such as +11, and t(11;14). The incidence of 11q23 involvement in M4 and M5 was higher than other subtypes of acute myeloid leukemia (AML). Ten cases with 11q23 abnormality had additional cytogenetic aberrations. In 30 cases treated with chemotherapy, 13 cases acquired complete remission (CR). The CR rate was lower than that of whole cases of acute myeloid leukemia(34.3% versus 64.0%). The CR rate of AML with 11q23 abnormality was lower than that of AML with normal karyotype (25% versus 55.6%). In other 10 patients with additional chromosome aberrations, the CR rate was lower than that of AML with 11q23 alone. In 7 patients with translocations at 11p15, only 3 patients acquired CR, and 2 patients relapsed early. Only 2 patients acquired CR in 5 patients with-11. CONCLUSION: 11q23 was a frequent aberration in chromosome 11 anomaly, which was often detected in M4 and M5. It might be associated with the pathogenesis of acute monolytic leukemia. The patients with chromosome 11 anomaly had poorer prognosis.     

组织金属蛋白酶抑制剂TIMP—2基因转染对胃癌细胞体内外侵袭能 …

了解ＴＩＭＰ－２基因转地胃癌细胞侵袭行为的影响，进行阻断肿瘤细胞侵转移的筛选尝试。     

脑康复冲剂对大鼠软脑膜微循环作用的实验研究

目的：脑康复冲剂临床用于治疗脑血栓血瘀证患者，本实验观察其对在大鼠实验性软脑膜微循环障碍的影响。方法：大鼠预防性给药，用高分子右旋糖酐水溶液静脉注射形成大鼠软脑膜的微循环障碍，观察脑康复冲剂对大鼠微循环的影响。结果：用高分子右旋糖酐造模后，大鼠软脑膜的微循环发生障碍，表现为血液流速减慢、血细胞聚集等，脑康复冲剂组血流速度开始减慢的时间明显比生理盐水对照组延长，且分级数也明显优于生理盐水组，对高分子右旋糖酐造成的血液流态障碍，脑康复组明显好于生理盐水组（P＜0．05），毛细血管网交叉点数开始减少的时间也比生理盐水对照组延长，差异显著（P＜0．01）。结论：脑康复冲剂使大鼠血流速度和血液流态得到改善，具有预防和改善动物脑微循环障碍的作用。     

Kv11.1 channel subunit composition includes MinK and varies developmentally in mouse cardiac muscle

The Kv11.1 (also ERG1) K(+) channel underlies cardiac I(Kr), a current that contributes to repolarization in mammalian heart. In mice, I(Kr) current density decreases with development and studies suggest that changes in the structure and/or properties of the heteromultimeric I(Kr)/Kv11.1 channel are responsible. Here, using immunohistochemistry, we report that total Kv11.1 alpha subunit protein is more abundant in neonatal heart and is distributed throughout both adult and neonatal ventricles with greater abundance in epicardia. Immunoblots reveal that the alpha subunit alternative splice variant, Kv11.1a, is more abundant in adult heart while the Kv11.1b variant is more abundant in neonatal heart. Additionally, MinK channel subunit protein is shown to co-assemble with Kv11.1 protein and is more abundant in neonatal heart. In summary, Kv11.1/I(Kr) channel composition varies developmentally and the higher I(Kr) current density in neonatal heart is likely attributable to higher abundance of Kv11.1/I(Kr) channels, more specifically, the Kv11.1b splice variant.     

脐带血血清中六种微量元素含量的研究

本对100例健康胎儿脐带血血清中六种微量元素（锌，铁，铜，钙，镁，锰）含量进行了测定，结果提示，所测的六种元素含量在男，田性胎儿之间似无明显差异（P＞0．05），与成人比较，胎儿的锌，铁，锰含量高于成人，铜，钙含量低于成人，镁含量与成人相近。     

STAg联合ESA鼻内免疫小鼠对弓形虫垂直传播的阻断作用

观察弓形虫可溶性速殖子抗原（Soluble tachyzoite antigen,STAg）与排泄-分泌抗原（Excreted/secreted antigens,ESA）单独或联合鼻内免疫小鼠对弓形虫垂直传播的阻断作用。分别用PBS 20μL和STAg 20μg、ESA 20μg及联合抗原（STAg 10μg＋ESA 10μg）鼻内免疫BALB/c处女鼠2次,间隔2周。末次免疫后第13天处女鼠与雄鼠以2∶1同居。妊娠第8天用弓形虫速殖子（8000个/只）灌胃攻击所有孕鼠。妊娠第18天处死,计算活胎率,并测定孕鼠肝、胎盘和胎鼠脑组织弓形虫抗原和孕鼠脾组织内虫荷,同时测定孕鼠小肠冲洗液SIgA、血清IgG水平。结果表明,ESA组和联合抗原组活胎率显著高于PBS组,STAg组、ESA组和联合抗原组胎盘及胚胎感染率均低于PBS组,联合抗原组最低。孕鼠在弓形虫速殖子攻击后,PBS组明显出现竖毛、倦怠、腹部塌陷等异常表现,感染率为100%,死亡率为22.22%,而STAg组、ESA组和联合抗原组有轻微症状,感染率分别为85.71%、57.14%、57.14%,死亡率分别为16.67%、0%、0%。STAg组、ESA组和联合抗原组脾组织内虫荷均显著低于PBS组,减虫率分别为72.19%、72.29%、78.45%,ESA组和联合抗原组小肠冲洗液特异性SIgA均显著高于PBS组,联合抗原组最高,血清特异性IgG抗体水平差异不显著。由此可见,ESA单独或与STAg联合免疫可诱导孕鼠小肠液高水平SIgA,显著降低脾组织虫荷,显著提高胚胎存活率,表现出明显的垂直传播阻断的作用。