Towards on-site pathogen detection using antibody-based sensors

In this paper, the recent progress within biosensors for plant pathogen detection will be reviewed. Bio-recognition layers on sensors can be designed in various ways, however the most popular approach is to immobilise antibodies for specific capture of analytes. Focus will be put on antibody surface-immobilisation strategies as well as the use of antibodies in the widely used sensors, quartz crystal microbalance, surface plasmon resonance and cantilevers. We will describe the available data on antibody-based plant pathogen detection and furthermore use examples from detection of the pathogens Salmonella, Listeria monocytogenes, Streptococcus mutans, Bacillus cereus, Bacillus anthracis, Campylobacter and Escherichia coli. We will touch upon optimal assay design and further discuss the strengths and limitations of current sensor technologies for detection of viruses, bacteria and fungi.     

Segmented lymph nodes in man

Segmentary lumbar, posterior pancreato-duodenal and inferior tracheobronchial lymph nodes have been investigated macro- and microscopically. The segmentary lymph nodes reach 12 X 45 X 45 mm, 10 X 25 X 100 mm in size. Most often these nodes are found among the posterior pancreato-duodenal lymph nodes (92%). They represent a conglomerate of smaller lymph nodes growing together and having their own capsule, parenchyma, sinuses, afferent and deferent lymph vessels and are united into one large node.     

Senile changes in human lymph nodes

BACKGROUND: The degenerative process of lymph nodes is poorly documented. METHODS: 161 lymph nodes of seven fresh and one embalmed human cadavers in the head and neck were studied. We used 6% hydrogen peroxide, lead oxide injectant, and radiographs to demonstrate lymphatic vessels, and found both solidified and transparent lymph nodes. They were removed, fixed in 10% formalin and sent for histopathology cross section. RESULTS: Thirty-eight solidified and 123 transparent lymph nodes were found. A series of histopathological sections show the degenerative process is variable and continuous. Senile involution affects all elements of the lymph node including the cortex, the medulla, and the architecture. CONCLUSION: This study provides actual anatomical and histopathological images of lymph nodes in different degenerative stages in the head and neck region. It may help explain some clinical conditions in the elderly, especially their diminished immunological response to infection and cancer metastasis.     

The detection of in vitro monocyte-macrophage colony-forming cells in mouse thymus and lymph nodes.

In vitro monocyte-macrophage colony-forming cells (CFC) have been detected in the thymus (30/10(6) cells) and in the cervical (22/10(6)) and mesenteric (20/10(6)) lymph nodes (LN) of the mouse. Thymus and LN derived CFC differed from bone marrow derived CFU-c in several characteristics parameters: (1) sole specificity of PMUE to induce colony formation (CF), (2) apparent singular line of monocyte-macrophage differentiation, (3) a marked 6- to 10-day lag period prior to initiation of CF, and (4) significantly slower rates of appearance of colonies in culture after initiation of CF. Two of these parameters are shared with those CFC detected within alveolar space, peritoneal exudate and pleural effusion. These are the delay prior to CF and the singular monocyte-macrophage differentiation. These similarities suggested that T-CFC and LN-CFC are probably of similar origin and represent, as suggested by Lin and Stewart ('74), a population of progenitor cells exclusively for monocyte-macrophages.     

超微超顺磁性氧化铁纳米粒检测良恶性淋巴结的实验研究

目的:研究超微超顺磁性氧化铁纳米粒(USPIO)增强MRI检测正常、反应性增生淋巴结和肿瘤转移淋巴结的价值.方法:新西兰免24只,静脉注射0.2mmolFe/kg的USPIO,原子吸收光谱仪检测兔体内脏器铁含量.另取4只兔,作为正常淋巴结组.4只兔双侧后腿肌肉注射蛋黄乳胶,用于建立腘窝反应性增生淋巴结模型,4只兔后腿肌肉接种VX2肉瘤,用于建立腘窝肿瘤转移淋巴结模型.3组动物均静注0.2mmolFe/kg的USPIO,于注射前、注射后12h分别行MRI扫描,观察淋巴结信号强度变化.扫描后取出淋巴结,行HE染色、普鲁士蓝染色观察淋巴结结构变化,铁颗粒的存在,原子吸收光谱仪检测铁含量.结果:USPIO在兔体内血循环时间较长(>12h),除脾肝肺外,其主要分布至淋巴结等网状内皮细胞和吞噬细胞.MRI平扫时,正常、反应性增生淋巴结和肿瘤转移淋巴结T2信号强度无显著差异,静注USPIO后,正常、反应性增生淋巴结中心T2信号强度明显降低,肿瘤转移淋巴结信号强度无明显变化.HE染色、普鲁士蓝染色和原子吸收光谱仪检测显示,正常、反应性增生淋巴结均舍有USPIO铁颗粒,而肿瘤转移性淋巴结淋巴结结构丧失,未见铁颗粒.结论:静脉注射USPIO后MR成像可用来鉴别良恶性淋巴结.     

Human cytomegalovirus genome sequences in lymph nodes

Human cytomegalovirus (CMV) is a major cause of morbidity in heart and lung transplant patients, resulting from immunosuppression-mediated reactivation of latent CMV originating either from the transplanted tissue, or the recipient. We showed that out of eight donor/recipient pairs, the lymph nodes (LNs) of three donors and four recipients, all CMV seropositive, harboured CMV DNA at exceeding levels compared with those of matched blood samples, as well as CMV RNA otherwise undetectable in patients' blood. On follow-up, patients positive for CMV DNA and RNA in LNs developed viraemia 4 to 5 weeks earlier than those initially polymerase chain reaction-negative for CMV. Our results indicate that LN are a significant site for sequestration and persistence of CMV and that LN may be important in seeding of CMV-infected cells into the circulation.     

Label-free protein and pathogen detection using the atomic force microscope

The atomic force microscope (AFM) uses a sharp micron-scale tip to scan and amplify surface features, providing exceptionally detailed topographical information with magnification on the order of x10(6). This instrument is used extensively for quality control in the computer and semiconductor industries and is becoming a progressively more important tool in the biological sciences. Advantages of the AFM for biological application include the ability to obtain information in a direct, label-free manner and the ability to image in solution, providing real-time data acquisition under physiologically relevant conditions. A novel application of the AFM currently under development combines its surface profiling capabilities with fixed immuno-capture using antibodies immobilized in a nanoarray format. This provides a distinctive platform for direct, label-free detection and characterization of viral particles and other pathogens.     

Specific pathogen detection using bioorthogonal chemistry and diagnostic magnetic resonance

The development of faster and more sensitive detection methods capable of identifying specific bacterial species and strains has remained a longstanding clinical challenge. Thus to date, the diagnosis of bacterial infections continues to rely on the performance of time-consuming microbiological cultures. Here, we demonstrate the use of bioorthogonal chemistry for magnetically labeling specific pathogens to enable their subsequent detection by nuclear magnetic resonance. Antibodies against a bacterial target of interest were first modified with trans-cyclooctene and then coupled to tetrazine-modified magnetic nanoprobes, directly on the bacteria. This labeling method was verified by surface plasmon resonance as well as by highly specific detection of Staphylococcus aureus using a miniaturized diagnostic magnetic resonance system. Compared to other copper-free bioorthogonal chemistries, the cycloaddition reaction reported here displayed faster kinetics and yielded higher labeling efficiency. Considering the short assay times and the portability of the necessary instrumentation, it is feasible that this approach could be adapted for clinical use in resource-limited settings.     

Sampling of sentinel lymph nodes: a simulation study

OBJECTIVE: To analyze the effects of various slicing schemes on the detection of metastases in lymph nodes. STUDY DESIGN: Use of an advanced computer simulation tool. RESULTS: Bisectioning along the longitudinal axis is an inadequate approach. Slicing ellipsoid lymph nodes along their longitudinal axis also results in a lower rate of detecting metastases since metastatic deposits have a predilection to localize subcapsularly. CONCLUSION: Ellipsoid lymph nodes must be sliced perpendicular to the longest axis to increase the rate of detecting metastases.     

Tuberculosis of the intercostal lymph nodes

OBJECTIVE: To describe tuberculosis of the intercostal lymph nodes and discuss its clinical and cytologic profile and pathogenesis. STUDY DESIGN: Fifteen cases from March 1994 to March 2000 were retrieved from our cytology records. Only clinically and therapeutically proven cases were included in the study. RESULTS: The ages of the patients ranged from 4 to 63 years. The male:female ratio was 2:1. The duration of disease at presentation ranged from one week to nine months. The lumps presented either in the parasternal region or between the midclavicular and posterior axillary lines. One case presented with an infrascapular lump. Most of the lumps were ill defined and cystic. Chest radiographs in all cases showed a soft tissue swelling without bony involvement. The aspirates were of two types, blood-mixed particles and necrotic material. Four cytologic pictures were seen: (1) epithelioid cell granulomas alone or (2) with necrosis or (3) with both necrosis and acid-fast bacilli (AFB), or (4) necrosis with AFB. AFB were detected in 53.3% of cases. CONCLUSION: If necrotic material is aspirated or if granulomatous inflammation is encountered in soft tissue swellings of the chest wall, particularly in the parasternal and axillary regions, the possibility of intercostal tuberculous lymphadenitis should be considered.     

Myocytes of the inguinal lymph nodes

Owing to the method for making total plane preparations of the capsule after A. V. Borisov, it is possible not only to prove presence of myocytes in the capsule and in the trabeculae of the inguinal lymph nodes in the man and rat, but to open out general regularities of their distribution and orientation. In the capsule areas, corresponding to the places, where the lymph nodules are adjacent to (zone A), the number of myocytes is the least. They are oriented in various directions and are in close contact with each other (fascicular-reticulate principle of distribution of myocytes). In the capsule areas, surrounding A zones (named B zones) the myocytes are situated in tight layers and have circulatory orientation. At the place where the afferent lymphatic vessel gets into the capsule, precapsular lymphangion makes an infundibular dilatation and its myocytes along the sloping spiral get into the capsule, where they are arranged circulatory and form a muscular "constrictor". While studying ultrastructure of myocytes in the rat inguinal lymph nodes, it has been found out that their structure is typical for the smooth muscle cells. There are numerous myo-myocytic contacts of nexus type, that unite the myocytes of the node into a single functional complex.