Validation of a decision support system for the cytodiagnosis of fine needle aspirates of the breast using a prospectively collected dataset from multiple observers in a working clinical environment

We have used a 692 case dataset, collected retrospectively by a single observer, to develop decision support systems for the cytodiagnosis of fine needle aspirates of breast lesions. In this study, we use a 322 case dataset that was prospectively collected by multiple observers in a working clinical environment to test two predictive systems, using logistic regression and the multilayer perceptron (MLP) type of neural network. Ten observed features and the patient age were used as input features. The systems were developed using a training set and test set from the single observer dataset and then applied to the multiple observer dataset. For the independent test cases from the single observer dataset, with a threshold set for no false positives on the training set, logistic regression produced a sensitivity of 82% (95% confidence interval 73-91) and a predictive value of a positive result (PV +) of 98% (95-99), the values for the MLP were 79% (69-89) and 100%, respectively. However the performance on the prospective multiple observer dataset was much worse, with a sensitivity of 72% (65-80), and PV + of 97% (94-99) for logistic regression and 67% (60-75) and 91% (85-97) for the MLP. These results suggest that there is considerable interobserver variability for the defined features and that this system is unsuitable for further development in the clinical environment unless this problem can be overcome.     

Diagnostic value of lymph node fine needle aspiration cytology: an institutional experience of 387 cases observed over a 5-year period

Lymph node fine needle aspiration (LNFNA) cytology is valuable in solving the diagnostic problems of clinical adenopathy. The usefulness of the procedure in the staging and diagnosis of various malignant and lymphoproliferative tumours, as well as its role in distinguishing reactive hyperplastic lymph nodes from lymphoma, has been documented in the literature generally on an individual basis. We report our cumulative 5 year experience of LNFNA representing 387 cases. Approximately half (n = 182) were diagnosed as either metastatic carcinoma or melanoma; in 54 cases (30%) excisional biopsy or tissue study was performed to confirm the diagnosis; there was only one false-positive diagnosis of a metastatic squamous carcinoma rendered on a submandibular lymph node. Sixty-one lymphoma cases were successfully diagnosed via LNFNA with no false positives; concurrent flow cytometry was utilized in 51% (n = 31) of the 61 cases and supported the cytologic diagnosis of lymphoma in 27 of the 31 cases (87%). A benign or reactive lymph node process was also diagnosed via LNFNA alone or in combination with flow cytometry in 48 cases with only five false negatives, which included four cases of mantle cell lymphoma and one case of melanoma. Unsatisfactory cases accounted for 12%, and represented specimens obtained by 'Wang needle' or other emerging techniques. Our study demonstrates that LNFNA can be an accurate, economical and rapid diagnostic procedure.     

NaCl胁迫对高粱根、叶鞘和叶片液泡膜ATP酶和焦磷酸酶活性的影响

NaCl胁迫初期 ,Na 主要在根和叶鞘中积累。相应地 ,根和叶鞘液泡膜ATP酶和焦磷酸酶水解活性、依赖ATP和PPi的质子泵活性及Na /H 逆向转运活性均明显增加 ,根和叶鞘的生长没有受到抑制。NaCl胁迫后期 ,Na 开始向地上部分运输并在叶片中积累。此时 ,叶片液泡膜质子泵和Na /H 逆向转运活性开始增加 ,根和叶鞘的Na/K比增加 ,其液泡膜ATP酶和焦磷酸酶水解活性、质子泵活性和Na /H 逆向转运活性下降。相应地 ,根和叶鞘的生长也下降。当保温介质中Na/K比超过 1时 ,液泡膜微囊ATP酶和焦磷酸酶活性均随Na/K比的增加而下降。表明非盐生植物液泡膜质子泵在盐胁迫的初期对Na 在液泡内的积累及其耐盐性起重要作用     

树木根系衰老研究的意义与现状

树木根系是树木重要的组成部分,具有养分和水分的吸收、传输和储存、树体的固定与支撑等重要的生理功能．在树木根系形成以后,常常遭遇到养分和水分胁迫,因此,其养分和水分的吸收功能尤其重要,在森林土壤中,养分和水分具有很大的时间和空间异质性,随着养分和水分在时间和空间上的变化,树木及时地主动调整其碳在根系中的分配,从而导致部分根系衰老或死亡,在林学上,树木根系衰老与养分和水分吸收关系密切,因而与树木生产力有直接的关系．在生态系统乃至全球尺度上,树木根系衰老影响碳循环和养分循环,因为根系对碳的消耗占树木通过光合作用所固定的碳的比例相当大,且含有丰富的养分．树木根系衰老受许多环境因子的影响,生物因子有真菌、细菌、病毒、土壤小型动物等,非生物因子有水分、温度、土壤养分、重金属等,这些因子对树木根系衰老的影响机制并不相同,尽管在树木根系衰老研究领域取得了长足的进步,提出了许多不同的假设,但仍有许多问题尚未解决,这些假设也需要更多的实验来验证,运用细胞学、生物化学、土壤科学、遗传学等多学科的交叉研究可进一步揭示根系衰老的本质。     

拟南芥AST基因的精细作图

拟南芥(Arabidopsis thaliana(L.)Heynh.)ast(anthocyanin spottedtesta)突变体是由碳离子辐射诱导产生的与花青苷生物合成有关的基因突变体,受单隐性核基因控制.根据拟南芥数据库中的SNPs(single nucleotide polv-mophisms)序列和插入/缺失多态性(insertion/deletion polymorphisms)序列,设计了一系列分子标记.采用图位克隆策略,应用这些分子标记完成了对拟南芥AST基因的精细作图,成功地将AST基因定位到BAC克隆T13M11上,初步认为该BAC克隆中的基因T13M11.8可能是AST基因.该基因的DNA序列长1432bp,含有6个外显子和5个内含子,编码的蛋白与花青苷生物合成途径中的二氢黄酮醇-4-还原酶有较高的同源性.将进一步通过功能互补实验验证图位克隆的结果.     

Fine Needle Aspiration Cytology of Breast In Invasive Carcinoma of Tubular Type and In Radial Scar/Complex Sclerosing Lesions

Fine needle aspirates (FNA) from 31 invasive carcinomas of tubular type and 22 radial scar/complex sclerosing lesions (RS/CSL), diagnosed in Edinburgh between 1986 and 1991, were reviewed. the lesions in this study varied in size and palpability at presentation, but are of increasing interest in the differential diagnosis of non-palpable areas of increased mammographic density. In agreement with previously published information^1'5'8, it was found that the tubular cancers were usually selected for biopsy following aspiration, but less often definitively diagnosed as malignant. Nearly 50% of the RS/CSL group were correctly reported benign on cytology, but in 40%, biopsy was recommended to exclude malignancy. In addition, cytological features helpful in suggesting malignancy in aspirates from tubular cancers, also raised suspicion in aspirates from the RS/CSL group, with a risk of overdiagnosis of cancer.     

Comparison of methods of expression and measurement of cation exchange capacity of plant roots

Summary Cation exchange capacity (CEC) of roots of fifteen genetically different tea clones was measured and the values were expressed on surface area and weight basis. The precision of the two methods is almost identical. The weight basis is, however, preferred as it is more convenient and less time consuming.In another experiment. CEC was determined separately on whole root system and on fractionated root segments (i.e. white and brown root portions). Highly significant and positive relationship between CEC values obtained with whole roots and those calculated from the fractionated root segments indicates that CEC can be more successfully measured on whole roots without sacrificing accuracy. Practical implications of both the procedures in root CEC-nutrient uptake relationship study was discussed.     

Dry matter partitioning and root length/leaf area ratios in herbaceous perennial plants with diverse altitudinal distribution

Summary Partitioning patterns in 22 exclusively low and 27 exclusively high altitude perennial herbaceous species were examined in order to test the hypothesis that plants of high altitudes allocate more dry matter to below-ground parts and in particular to storage organs, than typical low altitude plants. Our results raise some doubts about the general validity of this hypothesis. The mean fractions of total dry matter allocated to green leaves (22±2% s.e. at low and 24±2% at high altitude) and special storage organs (28±4% at both altitudes) do not differ significantly among sites. The mean relative portions of total dry matter allocated to above-ground plant parts amount to 57±3% at low and 42±3% at high elevation (P=0.002) and differ less than often assumed. The greater below-ground fraction at high altitude results from reduced stem and proportionally increased fine root compartments. At high altitude specific root length is increased by 50% and mean individual rooting density is tripled. Fine root length per unit leaf area is 4.5 times greater (P<0.001). However, interspecific variation in all these quantities is considerable and species with quite contrasting partitioning patterns coexist at both elevations. This suggests that the success of perennial herbaceous plants at high elevations does not necessarily depend on a large below ground biomass fraction. The increased fine root length at high altitude may substitute for reduced mycorrhizal infection. Figure 1 provides a graphical summary.