Single cell protein as an occupational hazard

Single cell protein (SCP) intended for animal feed purposes was produced in a pilot plant. The SCP consisted of Methylomonas methanolica, a pseudomonas species which is an obligate methanol user. The SCP was cultured in fermenters and later dewatered and dried in a spray-drier. Seven of eight research workers had febrile reactions 6-12 hours after exposure to SCP dust. All workers had high titres of IgG and IgM antibodies against the pseudomonas species as measured with indirect ELISA and passive haemagglutination techniques. The mechanism behind the febrile reaction is judged to be a non-immunological reaction caused by endotoxins. By increasing the particle size of the SCP through using different drying procedures, a product which generated less dust was obtained.     

Single cell protein as an occupational hazard.

Single cell protein (SCP) intended for animal feed purposes was produced in a pilot plant. The SCP consisted of Methylomonas methanolica, a pseudomonas species which is an obligate methanol user. The SCP was cultured in fermenters and later dewatered and dried in a spray-drier. Seven of eight research workers had febrile reactions 6-12 hours after exposure to SCP dust. All workers had high titres of IgG and IgM antibodies against the pseudomonas species as measured with indirect ELISA and passive haemagglutination techniques. The mechanism behind the febrile reaction is judged to be a non-immunological reaction caused by endotoxins. By increasing the particle size of the SCP through using different drying procedures, a product which generated less dust was obtained.     

单细胞凝胶电泳技术及其应用进展

单细胞凝胶电泳又称彗星试验 ,是一种在单细胞水平上检测DNA单、双链断裂和碱性不稳定位点的方法 ,具有敏感、稳定、快速的优点。近些年来 ,该方法广泛应用于DNA修复、遗传毒理、环境监测和细胞凋亡的研究。本文就彗星试验结合荧光原位杂交、检测DNA碱基氧化损伤、以及在染色、玻片储存和彗星图像分析方面的进展进行了综述     

单细胞的DOP—PCR—CGH分析

为探索退变寡核甘酸引物多聚酶链反应(DOP-PCR)比较基因组杂交(CGH)单细胞基因组研究的可能性,用DOP-PCR扩增正常XX、XY,异常XO、XXY、13三体和21三体单个细胞基因组DNA,经萤光标记后,分别以正常男性基因组DNA和正常男性单个淋巴细胞DOP—PCR产物为参照,进行CGH分析。结果以基因组DNA为参照的CGH双色荧光强度比均数波动围大,约30％区域的标准差超过正常允许范围,X染色体呈假性过度表达,未能检出13,21三体。以单细胞DOP-PCR产物为参照的CGH强度比均数接近期望值1.0,仅6％的标准差超出正常波动范围,13和21三体的相应染色体大部分常染色质区过度表达。结论:单细胞DOP-PCR存在非随机的不均匀扩增,其对CGH的影响,能通过应用单细胞DOP-PCR产物为参照而得以纠正。单细胞DOP-PCR-CGH及其用于着床前胚胎及母体血胎儿单细胞全基因组研究具有可能性。     

DNA损伤检测—单细胞凝胶电泳技术的研究

单细胞凝胶电泳(SCGE)又称为彗星实验,是一种可以在单个细胞水平上检测DNA断裂的技术。近年来该技术被广泛应用于特定的DNA损伤、DNA特异性染色、DNA修复、遗传毒理、环境生物监测等方面的研究。在前人的基础上对该实验方法做了进一步的研究和改进,使改进后的方法更加快速简捷、经济可行。     

Single cell DNA analysis: possibilities, methods, implications in relation to stem cell therapy

In the analysis of circulating tumor cells or in the preimplantation genetic diagnosis it is frequently necessary to examine one single cell. Some methods are appropriate to isolate single cells: Laser Assisted Microdissection, magnetic cell separation or FACS. The use of the whole genome amplification methods are needful, because the amount of the DNA extracted from the isolated cells is very low and inappropriate for additional examinations. With different molecular biological methods (e.g. sequencing, chip-technology) it is possible to determine genetic alterations in the analysed cells, and to return the modified cells with in vitro gene technological methods (viral vectors, non viral methods). Our aim is to summarize the methods and the possible technical problems developing during the process of the single cell molecular biological analysis.     

Single CX3CL1-Ig DNA administration enhances T cell priming in vivo

Upon antigenic stimulation, establishment of adaptive immune responses that determines vaccine efficacy is dependent on efficient T cell priming. Here, single CX3CL1-Ig DNA administration, a unique ligand of CX3CR1, together with viral or tumor antigens induced a strong in vivo antigen-specific T cell proliferation and effector function that was enough efficient to protect against a tumor challenge. We also showed that early expression of CX3CL1-Ig and antigens in muscle and lymphoid organs induces an increased in vivo migration of myeloid CD14+CD11c+ DC but not lymphoid CD8alpha+CD11c+ DC at these sites. Thus, by effectively directing DC toward lymphoid organs to encounter T cells, CX3CL1-Ig become a new candidate that augments T cell priming and increases efficiency of vaccination.     

Single nucleotide polymorphisms in cell wall biosynthesis-associated genes and phylogeny of Mycobacterium tuberculosis lineages

To investigate specific single nucleotide polymorphisms (SNPs) of different lineages of Mycobacterium tuberculosis, cell wall biosynthesis-associated genes encoding antigen 85 complex (fbpA, fbpB, and fbpC) and mannosyltransferase (pimB) were analyzed. Genetically diversified and predominant M. tuberculosis and Mycobacterium bovis genotypes identified in Taiwan (26 Beijing and 44 non-Beijing) were included in the study. Sequence analyses revealed that nine novel SNPs were found within main lineages of M. tuberculosis complex, including East-African-Indian (EAI), Beijing, Central-Asian (CAS), Bovis, and one lineage containing Latin American and Mediterranean (LAM), Haarlem and T. Specifically, a SNP in pimB codon 270 was identified in EAI, fbpA codon 156 in ancestral Beijing, fbpB codon 238 in modern Beijing, fbpA codon 4 and fbpC codon 158 in CAS, fbpA codon 311 in M. bovis and an additional SNP in fbpB codon 140 in M. bovis-BCG, and pimB codon 107 in other spoligotypes lineages including an additional SNP in fbpC codon 103 in LAM. In addition, we proved that isolates with spoligotype shared type (ST) no. 523 (carrying all 43 spacers), designated as unknown lineage in an international spoligotyping database (SpolDB4), belong to an early ancestral Beijing sublineage. Accordingly, a phylogenetic tree was constructed using those SNPs, and an evolutionary hypothesis for lineages of M. tuberculosis was proposed. These novel lineage-specific SNPs will be informative genetic markers in molecular epidemiological and evolutionary studies of M. tuberculosis.     

矽肺早期诊断的生物标志物CC16和SP-D

矽肺是由于在生产过程中长期吸入含有游离二氧化硅粉尘而引起以肺组织纤维化为主的全身性疾病,是尘肺中危害最严重的职业病之一。其病理演化过程为与炎性有关的纤维化反应。近几年一些学者在研究矽肺的致病机制过程中发现CC16、SP-D的抗炎及抗纤维化等作用在矽肺发生发展过程中起到重要作用,并可能成为矽肺早期诊断的生物标志物。本文就它们在矽肺诊断中的价值作一简单介绍。     

Bovine milk antibodies against cell surface protein antigen PAc-glucosyltransferase fusion protein suppress cell adhesion and alter glucan synthesis of Streptococcus mutans.

Cell surface protein antigen (PAc) and glucosyltransferases (GTF) produced by Streptococcus mutans are considered major colonization factors of the organism, and the inhibition of these factors is thought to prevent dental caries. In this study, 8-mo-old pregnant Holstein cows were immunized with fusion protein PAcA-GB, a fusion of the saliva-binding alanine-rich region (PAcA) of PAc with the glucan binding (GB) domain of GTF-I, an enzyme catalyzing the synthesis of water-insoluble glucan from sucrose. High titers of immunoglobulin antibodies specific for the fusion protein were found in normal milk after reimmunization, and they persisted for approximately 3 mo. The immunoglobulin G (IgG) antibodies against PAcA-GB were purified from immunized milk. The antibodies significantly inhibited the adhesion of S. mutans cells to saliva-coated hydroxyapatite beads. IgG antibodies purified from immunized milk also inhibited total glucan synthesis by cell-associated GTF preparation and GTF-I from S. mutans. The immunized milk may be useful as a means of passive immunization for the prevention of dental caries in humans.     

ATM蛋白激酶促细胞增殖作用研究进展

一直以来,共济失调毛细血管扩张突变基因(ATM)编码的蛋白激酶相关研究主要集中在DNA双链断裂损伤修复领域。近年来越来越多研究表明,氧化激活的ATM激酶具有重要的促细胞增殖作用,其潜在的机制与其氧化还原稳态维持功能、糖代谢调控功能和细胞增殖信号通路活性调节功能等密切相关。本文综述ATM激酶相关研究进展,尤其是其增殖调控功能相关研究,将有利于深入了解ATM蛋白激酶促细胞增殖的机制及其临床应用。     

活化蛋白-1和细胞周期蛋白在石英诱导的细胞周期改变中的作用

目的 探讨在石英刺激的人胚肺成纤维细胞(HELF)中AP-1/细胞周期蛋白D1 (cyclin D1)通路在细胞周期改变中的作用.方法 建立稳定转染空载体PXJ的HELF系(HELF-PXJ)及空载体PXJ与反义cyclin D1质粒或反义细胞周期蛋白依赖激酶(CDK4)质粒分别共转染的HELF系(简称anti-D1和anti-K4),将HELF-PXJ、anti-D1和anti-K4细胞分为对照组和石英刺激组(共6组),各对照组不加任何处理,石英刺激组用200 μg/ml石英处理细胞24h.检测AP-1对石英诱导的cyclin D1、CDK和E2F-4表达改变的影响.AP-1的化学抑制剂姜黄素(curcumin) 20μmol/L预处理细胞1h后,200 μg/ml石英刺激24 h,将HELF分为4组,分别为HELF对照组、HELF+石英组、HELF+curcumin对照组、HELF+curcumin+石英组.用免疫印迹(Western blot)法和免疫荧光法检测cyclin D1、CDK4和E2F-1/4蛋白表达;运用反义RNA技术证明通路的上下游关系;用流式细胞术检测细胞周期变化.结果 200 μg/ml石英处理HELF细胞,cyclin D1和CDK4蛋白表达升高,E2F-4蛋白表达明显降低,而E2F-1蛋白的表达没有明显改变.HELF-PXJ+石英组G1期细胞所占比例下降,S期细胞所占比例升高,与HELF-PXJ对照组的差异有统计学意义(P＜0.05).抑制cyclin D1或CDK4表达后,与对照组比较,anti-D1+石英组和anti-K4+石英组G1期细胞和S期细胞百分比无明显变化.抑制AP-1活性,与HELF+石英组比较,HELF+curcumin+石英组cyclin D1和CDK表达均减低,E2F-4表达增多.结论200μg/ml石英可诱导cyclin D1和CDK4蛋白表达增高,E2F-4蛋白表达减少,并通过AP-1/cyclin D1通路诱导细胞周期改变.     

思维单一是缺陷

不久前，我在市中心人民医院传染科进修。晚7点急诊收一病人入院，在一大帮儿女的陪护下，老人被抬进了病房。     

Iron and protein sufficiency and red cell indices in phenylketonuria

OBJECTIVE AND METHODS: We reviewed records of 41 children with treated phenylketonuria (PKU) in order to evaluate hematopoiesis and the effect of iron and protein sufficiency. RESULTS: Six children (15%) were found to have anemia. Combined depletion of iron and protein stores was most likely to result in anemia, and two of the three children with this finding were anemic. Four children (10%) had evidence of iron deficiency without anemia (a precursor stage of iron deficiency anemia). Clinically significant iron depletion was found in older as well as younger children (well beyond the traditional infant/toddler deficient years). Plasma albumin was normal in all children and was not adequately sensitive to detect protein depletion sufficient to cause anemia or decreased growth. However, low plasma prealbumin (a more sensitive marker of protein sufficiency) correlated significantly with altered hematopoiesis or poor growth. CONCLUSION: Compared to non-affected individuals, children with treated PKU make fewer red cells that have normal volume but increased hemoglobin per cell, resulting in a lower calculated hematocrit when measured by electronic cell counting. In the presence of iron or protein depletion, anemia may result. Routine monitoring of ferritin, complete blood counts and prealbumin are recommended for children with PKU at all ages.     

石英通过丝裂素活化蛋白激酶通路引起人胚肺成纤维细胞周期的改变

目的 探讨在石英刺激的人胚肺成纤维细胞(human embryo lung fibroblasts,HELF)中细胞外信号调节蛋白激酶(ERK)、应激活化蛋白激酶(JNK),细胞周期蛋白DI(cyclin D1)通路在石英诱导的细胞周期改变中的作用.方法 建立稳定转染转录因子AP-1荧光素酶报告基冈质粒的HELF系(HELF-AP-1)及AP-1荧光素酶报告基因质粒与丝裂素活化蛋白激酶(MAPK)显性失活突变体质粒(DN-ERK、DN-JNK和DN-p38)分别共转染的HELF系(简称DN-ERK、DN-JNK和DN-p38).将HELF-AP-1、DN-ERK、DN-JNK和DN-p38细胞分为对照组和石英组(共8组),各对照组不加任何处理,石英组用200 μg/ml石英处理HELF细胞24 h.用免疫印迹(Western blot)法和免疫荧光法检测cyclin D1、细胞周期蛋白依赖激酶4(CDK4)和E2F-4蛋白表达;采用显性失活突变体技术验证MAPKs信号转导通路的上下游关系及其与细胞周期的关系;用流式细胞术检测细胞周期变化.结果 HELF-AP-1+石英组G1期细胞所占比例下降,S期细胞所占比例升高,与HELF-AP-1对照组的差异有统计学意义(P＜0.05).抑制ERK或JNK表达后,与HELF-AP-1对照组比较,DN-ERK+石英组和DN-JNK+石英组G1期细胞百分比无明显变化.抑制p38后,DN-p38+石英组G1期细胞百分率明显下降,与HELF-AP-1对照组的差异有统计学意义(P＜0.05).与HELF-AP-1石英组比较,DN-ERK+石英组和DN-JNK+石英组CDK4表达降低和E2F-4表达增多,而DN-p38+石英组CDK4表达和E2F-4表达没有改变.与HELF-AP-1+石英组比较,DN-ERK+石英组和DN-JNK+石英组cyclin D1表达降低,而DN-p38+石英组cyclin D1没有改变.结论 ERK和JNK通过cyclin D1和CDK4介导石英诱导的HELF的细胞周期改变,而石英诱导的细胞周期改变与p38无关.

Abstract：

Objective To investigate the roles of mitogen-activated protein kinases (MAPK) on silica-induced cell cycle changes. Methods After cells were treated with 200 μg/ml silica, Western blot and Immunofluorescence assays were utilized to detect the expression of cyclin D1, CDK4 and E2F-4, Flow cytometry was used to detect cell cycle progression, the dominant negative mutants techniques were used to investigate silica-induced signal pathway and the effects of which in silica-induced cell cycle changes. Results After cells were exposed to 200 μg/ml silica 24 h, the results of present study showed the proportion of cells in G1 phases was decreased. Silica-induced cell cycle alternation was markedly impaired by stable expression of a dominant negative mutants of ERK or JNK, but not p38. It was found that ERK and JNK were involved in silica-induced cyclin D1 and CDK4 overexpression and the decreased expression of E2F-4. Conclusion ERK and JNK, but not p38, mediated silica-induced cell cycle changes in human embryo lung fibroblasts.     

C-reactive protein and interleukin-6 are decreased in transgenic sickle cell mice fed a high protein diet

Sickle cell disease is associated with hypermetabolism and a consequent shortage of substrates for normal growth and healthy immune response. The protein:energy ratio is a major determinant of dietary adequacy; the requirement for optimal growth of control mice is 20% of energy from dietary protein. This study investigated the efficacy of increased dietary protein for improving weight gain and reducing inflammation in the Berkeley sickle cell mouse model (S). The study examined the effect of diet on weight gain and circulating levels of 2 inflammatory proteins, C-reactive protein (CRP), and cytokine interleukin-6 (IL-6). Male C57BL/6 (C) control (n = 8) and S mice (n = 8) were randomized at weaning to 40 d of isoenergetic diets containing 20% (normal) and 35% (high) of energy from protein (C20, C35, S20, S35), replacing dextrin. Rate of weight gain was calculated and plasma CRP and IL-6 concentrations determined by ELISA. Liver mRNA expression of these proteins was measured by real-time PCR and L-arginase by colorimetric assay. S35 mice tended to gain weight more rapidly than S20 mice (P = 0.06) and more rapidly than C35 mice (P < 0.01). Circulating CRP and IL-6 levels were also lower in S35 mice than in S20 mice (P < 0.05), as was liver CRP mRNA expression (P < 0.01). These results demonstrate that introducing a high protein diet at weaning attenuates the steady-state inflammation in this S mouse model. Dietary L-arginine availability was investigated as a possible mechanism for increased nitric oxide production and consequent reduced inflammation.