'Juvenile' myasthenia gravis in early infancy

A previously well infant developed severe muscle weakness and hypotonia at 6 months of age. This was reversed by anticholinesterase medication. However, she had subsequent further weakness and died at 10 months after an acute respiratory arrest. The clinical pattern was that of the 'juvenile' form of myasthenia gravis rather than the 'congenital' forms which have previously been described in early infancy.     

Molecular characterization of a glycosylphosphatidylinositol-linked ADP- ribosyltransferase from lymphocytes

Mono ADP-ribosyltransferases catalyze the transfer of the ADP-ribose moiety of nicotinamide adenine dinucleotide (NAD) to proteins. It was reported by Wang et al (J Immunol 153:4048, 1994) that incubation of mouse cytotoxic T lymphocytes (CTL) with NAD resulted in the ADP- ribosylation of membrane proteins and inhibition of cell proliferation and cytotoxicity. Treatment of CTL with phosphatidylinositol-specific phospholipase C (PI-PLC) before incubation with NAD prevented the inhibitory effects of NAD on the cells, consistent with the removal of a glycosylphosphatidylinositol (GPI)-anchored ADP-ribosyltransferase on the lymphocyte surface. We have identified and cloned a GPI-linked ADP- ribosyltransferase from Yac-1 mouse T-cell lymphoma cells. The deduced amino acid sequence of the Yac-1 transferase was 70% and 41% identical to those of the rabbit skeletal muscle and chicken heterophil, respectively. It contained three noncontiguous sequences similar to those found in several of the bacterial toxin and vertebrate ADP- ribosyltransferases. Based on crystallography of the bacterial toxins, these regions are believed to form, in part, the catalytic site consistent with a common mechanism for the ADP-ribose transfer reaction. In rat mammary adenocarcinoma (NMU) cells transformed with the Yac-1 transferase cDNA, transferase activity was present on the cell surface and was released into the medium by treatment of cells with PI-PLC. Thus, we have cloned a novel gene that has properties identical to the transferase detected in CTL, and may be involved in the NAD-dependent regulation of proliferation and cytotoxicity.     

组成型αB晶体蛋白在热休克蛋白核转录因子1敲除小鼠心肌中的表达

目的:了解热休克蛋白核转录因子1(HSF1)对小鼠心肌组成型αB晶体蛋白(αB-Crystallin,αBC)表达的影响.方法:用western blot和免疫组织化学的方法,测定组成型αBC在HSF1基因野生型(hsf1+/+)和HSF1基因敲除型(hsf1-/-)小鼠心肌中的表达.结果:αBC在hsf1-/-和hsf1+/+小鼠心肌表达量分别为68.42±4.16和100.00±7.58(心肌可溶性组分,P＜0.05),20.35±1.01和37.55±1.91(心肌不可溶性组分,P＜0.05);免疫组化显示αBC在hsf1-/-心肌细胞内的表达信号较hsf1+/+明显减弱.结论:HSF1基因是介导组成型αBC基因表达重要的、但不是惟一的因子.     

Molecular phenotype of a human lymphoblastoid cell-line homoplasmic for the np 7445 deafness-associated mitochondrial mutation

We have studied mitochondrial gene expression and metabolic function in a human lymphoblastoid cell-line homoplasmic for the np 7445, deafness- associated mitochondrial DNA mutation. The mutation maps to the 3' termini of the oppositely oriented genes encoding cytochrome oxidase subunit I (COI) and tRNA-ser(UCN). In comparison with control lymphoblastoid cells, we detected a marked depletion (> 60%) of tRNA- ser(UCN). There was, however, no significant impairment of respiratory function, no alteration to the structure or abundance of COI mRNA or its precursors, and no detectable abnormality of mitochondrial protein synthesis. We also found considerable tissue-variation in the abundance of tRNA-ser(UCN). We propose that the tissue-specific phenotype associated with this mutation results from an inherent deficiency in the processing of the mutant pre-tRNA, that becomes limiting for protein synthesis only in a restricted set of cells of the auditory system in which the tRNA is, for other reasons, already at a critically low level.      

Sources and sequelae of bacterial contamination of hematopoietic stem cell components: implications for the safety of hematotherapy and graft engineering

Background: It is important to compare the incidence of bacterial contamination of components collected from the peripheral blood or bone marrow (BM), as well as of components processed with or without cell selection or depletion, and to evaluate the sequelae of such contamination. Study Design and Methods: Bacterial contamination rates were compared in 1380 untreated autologous peripheral blood progenitor cells (PBPCs), 291 untreated autologous BM samples, 916 monoclonal antibody (MoAb)-treated autologous and allogeneic BM samples, and in 45 autologous PBPC components from which the CD34+ cells were selected. Bacterial cultures were performed at sequential time points during the processing of MoAb-treated BM. Results: Bacterial contamination was documented in 44 of 2632 components from 1593 patients (1.67% of components, 2.76% of patients) before cryopreservation. Although only 0.65% of untreated PBPCs were contaminated before cryopreservation, each patient was more likely to have given a contaminated PBPC component than a contaminated BM component (2.41% vs. 0%, p < 0.01). Bacterial contamination of MoAb-treated BM was greater during or after manipulation than it was before (2.33% vs. 0.77%, p < 0.05). At thawing, contamination was documented in 42 (1.97%) of 2136 components cultured. Ten (13.7%) of 73 patients who received hematopoietic progenitor cells that were contaminated before cryopreservation or at thawing developed fever or positive blood cultures within 48 hours of transfusion. Fever was associated with bacteremia in two cases, but no irreversible clinical sequelae were noted. Conclusion: These studies suggest that, despite careful attention to sterile procedures, low-level contamination of hematopoietic stem cell components can be introduced before or during manipulation as well as at thawing, and that standards for monitoring of the procedures for collection, processing, cryopreservation, thawing, and transfusion of hematopoietic progenitor cells are necessary.     

丹参通络解毒汤联合内皮祖细胞移植对心肌缺血再灌注损伤大鼠促血管新生作用的研究

目的探讨丹参通络解毒汤(DSTLJD)联合内皮祖细胞(endothelial progenitor cells, EPCs)移植对心肌缺血再灌注损伤(ischemic reperfusion injury, IRI)模型大鼠促血管新生作用的影响及其机制。方法采用密度梯度离心法及差数贴壁法分离和培养EPCs,采用免疫荧光法鉴定EPCs。通过结扎左冠状动脉左前降支的方法建立IRI模型,采用随机数字表法分为SH组(假手术组)、IRI组(模型组)、EPCs组(EPCs移植组)、DSTLJD组(丹参通络解毒汤组)、DSTLJD+EPCs组(丹参通络解毒汤+EPCs移植),每组10只。4周后,采用HE染色法观察心肌组织的病理形态,用免疫组化法测定各组大鼠心肌微血管计数(microvessel count, MVC)、心肌微血管密度(microvessel density, MVD),并检测各组大鼠血管内皮生长因子(vascular endothelial growth factor, VEGF)、碱性成纤维生长因子(basic fibroblast growth factor, bFGF)的蛋白表达。结果与IRI组比较,EPCs组、DSTLJD组、DSTLJD+EPCs组大鼠细胞肿胀及坏死程度减轻,MVC、MVD及VEGF、bFGF蛋白表达显著增高(P<0.01);与EPCs组相比,DSTLJD组、DSTLJD+EPCs组大鼠炎性细胞浸润及细胞肿胀程度轻微,MVC、MVD及VEGF、bFGF蛋白表达增高(P<0.05,P<0.01);与DSTLJD组相比,DSTLJD+EPCs组大鼠肌束排列较整齐,无明显细胞坏死,MVC、MVD及VEGF、bFGF蛋白表达明显增高(P<0.01)。结论丹参通络解毒汤联合EPCs移植可能通过上调VEGF、bFGF的表达,促进心肌IRI大鼠的血管新生,从而保护IRI心肌。     

Enhanced passive mixing for paper microfluidics

Imprecise control of fluid flows in paper-based devices is a major challenge in pushing the innovations in this area towards societal implementation. Assays on paper tend to have low reaction yield and reproducibility issues that lead to poor sensitivity and detection limits. Understanding and addressing these issues is key to improving the performance of paper-based devices. In this work, we use colorimetric analysis to observe the mixing behaviour of molecules from two parallel flow streams in unobstructed (on unpatterned paper) and constricted flow (through the gap of a patterned hourglass structure). The model system used for characterization of mixing involved the reaction of Fe³⁺ with SCN⁻ to form the coloured, soluble complex Fe(SCN)²⁺. At all tested concentrations (equal concentrations of 50.0 mM, 25.0 mM or 12.5 mM for KSCN and FeCl₃ in each experiment), the reaction yield increases (higher colorimetric signal) and better mixing is obtained (lower relative standard deviation) as the gap of the flow constriction becomes smaller (4.69–0.32 mm). This indicates enhanced passive mixing of reagents. A transition window of gap widths exhibiting no mixing enhancement (about 2 mm) to gap widths exhibiting complete mixing (0.5 mm) is defined. The implementation of gap sizes that are smaller than 0.5 mm (below the transition window) for passive mixing is suggested as a good strategy to obtain complete mixing and reproducible reaction yields on paper. In addition, the hourglass structure was used to define the ratio of reagents to be mixed (2 : 1, 1 : 1 and 1 : 2 HCl–NaOH) by simply varying the width ratio of the input channels of the paper. This allows easy adaptation of the device to reaction stoichiometry.

Efficient passive mixing can be achieved by contricting the reagent flow using structures having narrow gaps.