首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.

Objective

This study aimed to construct a model for using in differentiating benign and malignant nodules with the artificial neural network and to increase the objective diagnostic accuracy of US.

Materials and methods

618 consecutive patients (528 women, 161 men) with 689 thyroid nodules (425 malignant and 264 benign nodules) were enrolled in the present study. The presence and absence of each sonographic feature was assessed for each nodule - shape, margin, echogenicity, internal composition, presence of calcifications, peripheral halo and vascularity on color Doppler. The variables meet the following criteria: important sonographic features and statistically significant difference were selected as the input layer to build the ANN for predicting the malignancy of nodules.

Results

Six sonographic features including shape (Taller than wide, p<0.001), margin (Not Well-circumscribed, p<0.001), echogenicity (Hypoechogenicity, p<0.001), internal composition (Solid, p<0.001), presence of calcifications (Microcalcification, p<0.001) and peripheral halo (Absent, p<0.001) were significantly associated with malignant nodules. A three-layer 6-8-1 feed-forward ANN model was built. In the training cohort, the accuracy of the ANN in predicting malignancy of thyroid nodules was 82.3% (AUROC = 0.818), the sensitivity and specificity was 84.5% and 79.1%, respectively. In the validation cohort, the accuracy, sensitivity and specificity was 83.1%, 83.8% and 81.8%, respectively. The AUROC was 0.828.

Conclusion

ANN constructed by sonographic features can discriminate benign and malignant thyroid nodules with high diagnostic accuracy.  相似文献   

2.
A century ago, in his study of colour vision in the honeybee (Apis mellifera), Karl von Frisch showed that bees distinguish between a disc that is half yellow, half blue, and a mirror image of the same. Although his inference of colour vision in this example has been accepted, some discrepancies have prompted a new investigation of the detection of polarity in coloured patterns. In new experiments, bees restricted to their blue and green receptors by exclusion of ultraviolet could learn patterns of this type if they displayed a difference in green contrast between the two colours. Patterns with no green contrast required an additional vertical black line as a landmark. Tests of the trained bees revealed that they had learned two inputs; a measure and the retinotopic position of blue with large field tonic detectors, and the measure and position of a vertical edge or line with small-field phasic green detectors. The angle between these two was measured. This simple combination was detected wherever it occurred in many patterns, fitting the definition of an algorithm, which is defined as a method of processing data. As long as they excited blue receptors, colours could be any colour to human eyes, even white. The blue area cue could be separated from the green receptor modulation by as much as 50°. When some blue content was not available, the bees learned two measures of the modulation of the green receptors at widely separated vertical edges, and the angle between them. There was no evidence that the bees reconstructed the lay-out of the pattern or detected a tonic input to the green receptors.  相似文献   

3.
4.
Numerous studies have shown warning coloration to facilitate the discrimination of edible and inedible prey. However, inedible insect species may possess cryptic coloration as well. It has been shown that some other visual features (especially characteristic body shape) are sufficient for the recognition of some insect taxa (e.g. ladybirds, ants, wasps). We tested the ability of wild‐caught great tits (Parus major) to discriminate between the identically coloured edible (roach – Blaptica dubia) and the inedible (firebug – Pyrrhocoris apterus) as prey according to subtle peripheral visual traits (shape of legs and antennae, body posture, and means of locomotion). Both prey species were offered either simultaneously or alternately. The ability of the birds to learn was tested by means of fourteen trial repetitions in two sessions. In general, great tits were not able to learn to discriminate between firebugs and roaches by subtle shape cues alone during the two sessions. However, multivariate analysis of individual bird behaviour showed that they adopted one of three different attitudes to the presented prey. Most of the birds never attacked any or always attacked both prey. In addition, a small proportion of the birds was able to discriminate between the two prey types and attacked only roaches. Nevertheless, firebugs survived most of the attacks, which suggests that in case of chemically protected prey, the evolution of conspicuous coloration is not always the best/only option.  相似文献   

5.
作为种子捕食者和种子扩散者, 啮齿动物对产坚果植物的自然更新有很大作用。然而, 对啮齿动物鉴别虫蛀种子的能力颇有争议。2001 年秋季在中国四川都江堰市实验林场, 以3 种比例(I1∶S = 1∶1 , I1∶S = 4∶1 和I1∶I2∶S = 1∶1∶1)供给啮齿动物4 种壳斗科种子: 栓皮栎( Quercus variabilis) 、枹树( Q. serrata) 、青冈( Cyclobalanopsis glauca) 和栲树( Castanopsis fargesii) 的3 种坚果型(即饱满种子(S) , 不含象虫的虫蛀种子(I1) 和含象虫的虫蛀种子( I2 ) 验证了啮齿动物能够准确地鉴别虫蛀种子这一假说。结果表明, 在3 种比例下4 种坚果的虫蛀种子的消失速率均慢于饱满种子。即使虫蛀种子的比例增加, 啮齿动物显著地搬走了更多的饱满种子(67%~92%) 。当虫蛀种子的比例增加时, 虫蛀种子就地消耗和拒绝的比例降低, 搬走比例增加。啮齿动物并不拒绝虫蛀种子, 这可能与它们的可利用性(如象虫可以作为蛋白质的补充) 和数量以及它们的觅食行为有关。结果证实啮齿动物能准确地鉴别虫蛀种子, 从而有区别地搬走并贮藏更多的饱满种子, 消耗一部分可以利用的虫蛀种子(包括其内的象虫) 。这样, 啮齿动物通过对饱满种子和虫蛀种子的鉴别和选择会影响不同种子的命运, 从而对这些坚果植物的自然更新产生影响。  相似文献   

6.
目的:探讨血清降钙素原(procalcitonin,PCT)在鉴别诊断自身免疫性疾病活动期与细菌感染中的应用价值。方法:选择析深圳市保健办2011年1月-2012年3月收治的30例自身免疫性疾病活动期和34例细菌感染患者为研究对象,测定其血清c反应蛋白(C-reactive protein,CRP)和PCT的水平。结果:感染组患者CRP水平为(0.1162±0.0873)gm,PCT水平(2.37±7.02)±10^-3gm,自身免疫活动期患者CRP水平(0.0639±0.0687)gm,PCT浓度(0.09±0.08)×10^-3g/L。ROC曲线下面积(AUC)和95%可信区间(CI)分别为0.75和0186,0.61-0.83和0.74-0.94,差异具有统计学意义(P〈0.05)。CRP联合PCT水平预测的AUC为0.82.其与单独PCT水平相比没有显著性差别(P=0.74)。CRP的最佳临界值为0.0722g/L,灵敏度为73.5%,特异性为69.2%;PCT的最佳临界值为0.09×10^-3g/L,其灵敏度为82.1%,特异性为72.5%。结论:在鉴别活动期自身免疫疾病患者与细菌感染时,PCT的灵敏度与特异性比CRP高,但其联合CRP对此类诊断并无显著意义。  相似文献   

7.
Infectious disease surveillance is key to limiting the consequences from infectious pathogens and maintaining animal and public health. Following the detection of a disease outbreak, a response in proportion to the severity of the outbreak is required. It is thus critical to obtain accurate information concerning the origin of the outbreak and its forward trajectory. However, there is often a lack of situational awareness that may lead to over- or under-reaction. There is a widening range of tests available for detecting pathogens, with typically different temporal characteristics, e.g. in terms of when peak test response occurs relative to time of exposure. We have developed a statistical framework that combines response level data from multiple diagnostic tests and is able to ‘hindcast’ (infer the historical trend of) an infectious disease epidemic. Assuming diagnostic test data from a cross-sectional sample of individuals infected with a pathogen during an outbreak, we use a Bayesian Markov Chain Monte Carlo (MCMC) approach to estimate time of exposure, and the overall epidemic trend in the population prior to the time of sampling. We evaluate the performance of this statistical framework on simulated data from epidemic trend curves and show that we can recover the parameter values of those trends. We also apply the framework to epidemic trend curves taken from two historical outbreaks: a bluetongue outbreak in cattle, and a whooping cough outbreak in humans. Together, these results show that hindcasting can estimate the time since infection for individuals and provide accurate estimates of epidemic trends, and can be used to distinguish whether an outbreak is increasing or past its peak. We conclude that if temporal characteristics of diagnostics are known, it is possible to recover epidemic trends of both human and animal pathogens from cross-sectional data collected at a single point in time.  相似文献   

8.
The categorization of intraductal proliferative lesions of the breast based on routine light microscopic examination of histopathologic sections is in many cases challenging, even for experienced pathologists. The development of computational tools to aid pathologists in the characterization of these lesions would have great diagnostic and clinical value. As a first step to address this issue, we evaluated the ability of computational image analysis to accurately classify DCIS and UDH and to stratify nuclear grade within DCIS. Using 116 breast biopsies diagnosed as DCIS or UDH from the Massachusetts General Hospital (MGH), we developed a computational method to extract 392 features corresponding to the mean and standard deviation in nuclear size and shape, intensity, and texture across 8 color channels. We used L1-regularized logistic regression to build classification models to discriminate DCIS from UDH. The top-performing model contained 22 active features and achieved an AUC of 0.95 in cross-validation on the MGH data-set. We applied this model to an external validation set of 51 breast biopsies diagnosed as DCIS or UDH from the Beth Israel Deaconess Medical Center, and the model achieved an AUC of 0.86. The top-performing model contained active features from all color-spaces and from the three classes of features (morphology, intensity, and texture), suggesting the value of each for prediction. We built models to stratify grade within DCIS and obtained strong performance for stratifying low nuclear grade vs. high nuclear grade DCIS (AUC = 0.98 in cross-validation) with only moderate performance for discriminating low nuclear grade vs. intermediate nuclear grade and intermediate nuclear grade vs. high nuclear grade DCIS (AUC = 0.83 and 0.69, respectively). These data show that computational pathology models can robustly discriminate benign from malignant intraductal proliferative lesions of the breast and may aid pathologists in the diagnosis and classification of these lesions.  相似文献   

9.
Infection and inflammation are common complications that seriously affect the functionality and longevity of implanted medical implants. Systemic administration of antibiotics and anti-inflammatory drugs often cannot achieve sufficient local concentration to be effective, and elicits serious side effects. Local delivery of therapeutics from drug-eluting coatings presents a promising solution. However, hydrophobic and thick coatings are commonly used to ensure sufficient drug loading and sustained release, which may limit tissue integration and tissue device communications. A calcium-mediated drug delivery mechanism was developed and characterized in this study. This novel mechanism allows controlled, sustained release of minocycline, an effective antibiotic and anti-inflammatory drug, from nanoscale thin hydrophilic polyelectrolyte multilayers for over 35 days at physiologically relevant concentrations. pH-responsive minocycline release was observed as the chelation between minocycline and Ca2+ is less stable at acidic pH, enabling ‘smart’ drug delivery in response to infection and/or inflammation-induced tissue acidosis. The release kinetics of minocycline can be controlled by varying initial loading, Ca2+ concentration, and Ca2+ incorporation into different layers, enabling facile development of implant coatings with versatile release kinetics. This drug delivery platform can potentially be used for releasing any drug that has high Ca2+ binding affinity, enabling its use in a variety of biomedical applications.  相似文献   

10.
11.

Background

Malaria incidence is in decline in many parts of SE Asia leading to a decreasing proportion of febrile illness that is attributable to malaria. However in the absence of rapid, affordable and accurate diagnostic tests, the non-malaria causes of these illnesses cannot be reliably identified. Studies on the aetiology of febrile illness have indicated that the causes are likely to vary by geographical location within countries (i.e. be spatially heterogeneous) and that national empirical treatment policies based on the aetiology measured in a single location could lead to inappropriate treatment.

Methods

Using data from Vientiane as a reference for the incidence of major febrile illnesses in the Lao People''s Democratic Republic (Laos) and estimated incidences, plausible incidence in other Lao provinces were generated using a mathematical model for a range of national and local scale variations. For a range of treatment protocols, the mean number of appropriate treatments was predicted and the potential impact of a spatially explicit national empirical treatment protocol assessed.

Findings

The model predicted a negative correlation between number of appropriate treatments and the level of spatial heterogeneity. A spatially explicit national treatment protocol was predicted to increase the number of appropriate treatments by 50% for intermediate levels of spatial heterogeneity.

Conclusions

The results suggest that given even only moderate spatial variation, a spatially explicit treatment algorithm will result in a significant improvement in the outcome of undifferentiated fevers in Laos and other similar resource poor settings.  相似文献   

12.
13.
Heating competent bacteria of the Challis strain of Streptococcus at a temperature of 48 C causes them to lose their transformability and mainfest a slight retardation of growth rate without loss of viability. The heat-induced loss of transformability is due to diminution in the ability of the bacteria to bind deoxyribonucleic acid (DNA) irreversibly. Another effect of heat is upon a step in the transformation process subsequent to binding, a step in which DNA molecules will compete if they multiply infect an unheated cell. Despite the reduction in irreversible binding exhibited by heated cells, competition between DNA molecules to transform these cells is decreased. Neither of these sites affected by heat exhibits any specificity with regard to origin of DNA. Since heat treatment causes a relative stimulation of transformation by heterospecific DNA, a third effect of heat must be envisaged. The amount of heat-induced stimulation is dependent upon the amount of heterospecific material in the transforming DNA. Linkage of heterospecific markers is increased as a consequence of heating the recipients. Transformation by markers of different transforming efficiency in homospecific DNA is also affected by heat treatment in a differential manner. Taken together, these results point to a heat-sensitive intracellular mechanism that recognizes DNA base sequences during transformation. The effect of heat upon discrimination against heterospecific DNA has been found to occur also in the pneumococcus and in Bacillus subtilis.  相似文献   

14.
Physicians are regularly faced with severely ill patients at risk of developing infections. In literature, standard care wards are often neglected, although their patients frequently suffer from a systemic inflammatory response syndrome (SIRS) of unknown origin. Fast identification of patients with infections is vital, as they immediately require appropriate therapy. Further, tools with a high negative predictive value (NPV) to exclude infection or bacteremia are important to increase the cost effectiveness of microbiological examinations and to avoid inappropriate antibiotic treatment. In this prospective cohort study, 2,384 patients with suspected infections were screened for suffering from two or more SIRS criteria on standard care wards. The infection probability score (IPS) and sepsis biomarkers with discriminatory power were assessed regarding their capacity to identify infection or bacteremia. In this cohort finally consisting of 298 SIRS-patients, the infection prevalence was 72%. Bacteremia was found in 25% of cases. For the prediction of infection, the IPS yielded 0.51 ROC-AUC (30.1% sensitivity, 64.6% specificity). Among sepsis biomarkers, lipopolysaccharide binding protein (LBP) was the best parameter with 0.63 ROC-AUC (57.5% sensitivity, 67.1% specificity). For the prediction of bacteremia, the IPS performed slightly better with a ROC-AUC of 0.58 (21.3% sensitivity, 65% specificity). Procalcitonin was the best discriminator with 0.78 ROC-AUC, 86.3% sensitivity, 59.6% specificity and 92.9% NPV. Furthermore, bilirubin and LBP (ROC-AUC: 0.65, 0.62) might also be considered as useful parameters. In summary, the IPS and widely used infection parameters, including CRP or WBC, yielded a poor diagnostic performance for the detection of infection or bacteremia. Additional sepsis biomarkers do not aid in discriminating inflammation from infection. For the prediction of bacteremia procalcitonin, and bilirubin were the most promising parameters, which might be used as a rule for when to take blood cultures or using nucleic acid amplification tests for microbiological diagnostics.  相似文献   

15.

Background

Cardiovascular disease, a progressive manifestation of α-L-iduronidase deficiency or mucopolysaccharidosis type I, continues in patients both untreated and treated with hematopoietic stem cell transplantation or intravenous enzyme replacement. Few studies have examined the effects of α-L-iduronidase deficiency and subsequent glycosaminoglycan storage upon arterial gene expression to understand the pathogenesis of cardiovascular disease.

Methods

Gene expression in carotid artery, ascending, and descending aortas from four non-tolerized, non-enzyme treated 19 month-old mucopolysaccharidosis type I dogs was compared with expression in corresponding vascular segments from three normal, age-matched dogs. Data were analyzed using R and whole genome network correlation analysis, a bias-free method of categorizing expression level and significance into discrete modules. Genes were further categorized based on module-trait relationships. Expression of clusterin, a protein implicated in other etiologies of cardiovascular disease, was assessed in canine and murine mucopolysaccharidosis type I aortas via Western blot and in situ immunohistochemistry.

Results

Gene families with more than two-fold, significant increased expression involved lysosomal function, proteasome function, and immune regulation. Significantly downregulated genes were related to cellular adhesion, cytoskeletal elements, and calcium regulation. Clusterin gene overexpression (9-fold) and protein overexpression (1.3 to 1.62-fold) was confirmed and located specifically in arterial plaques of mucopolysaccharidosis-affected dogs and mice.

Conclusions

Overexpression of lysosomal and proteasomal-related genes are expected responses to cellular stress induced by lysosomal storage in mucopolysaccharidosis type I. Upregulation of immunity-related genes implicates the potential involvement of glycosaminoglycan-induced inflammation in the pathogenesis of mucopolysaccharidosis-related arterial disease, for which clusterin represents a potential biomarker.  相似文献   

16.
White spot syndrome caused by white spot syndrome virus (WSSV) is one of the most threatening diseases of shrimp culture industry. Previous studies have successfully demonstrated the use of DNA- and RNA-based vaccines to protect WSSV infection in shrimp. In the present study, we have explored the protective efficacy of antisense constructs directed against WSSV proteins, VP24, and VP28, thymidylate synthase (TS), and ribonucleotide reductase-2 (RR2) under the control of endogenous shrimp histone-3 (H3) or penaedin (Pn) promoter. Several antisense constructs were generated by inserting VP24 (pH3–VP24, pPn–VP24), VP28 (pH3–VP28, pPn–VP28), TS (pH3–TS, pPn–TS), and RR2 (pH3–RR2) in antisense orientation. These constructs were tested for their protective potential in WSSV infected cell cultures, and their effect on reduction of the viral load was assessed. A robust reduction in WSSV copy number was observed upon transfection of antisense constructs in hemocyte cultures derived from Penaeus monodon and Scylla serrata. When tested in vivo, antisense constructs offered a strong protection in WSSV challenged P. monodon. Constructs expressing antisense VP24 and VP28 provided the best protection (up to 90 % survivability) with a corresponding decrease in the viral load. Our work demonstrates that shrimp treated with antisense constructs present an efficient control strategy for combating WSSV infection in shrimp aquaculture.  相似文献   

17.
A class of discrete-time models of infectious disease spread, referred to as individual-level models (ILMs), are typically fitted in a Bayesian Markov chain Monte Carlo (MCMC) framework. These models quantify probabilistic outcomes regarding the risk of infection of susceptible individuals due to various susceptibility and transmissibility factors, including their spatial distance from infectious individuals. The infectious pressure from infected individuals exerted on susceptible individuals is intrinsic to these ILMs. Unfortunately, quantifying this infectious pressure for data sets containing many individuals can be computationally burdensome, leading to a time-consuming likelihood calculation and, thus, computationally prohibitive MCMC-based analysis. This problem worsens when using data augmentation to allow for uncertainty in infection times. In this paper, we develop sampling methods that can be used to calculate a fast, approximate likelihood when fitting such disease models. A simple random sampling approach is initially considered followed by various spatially-stratified schemes. We test and compare the performance of our methods with both simulated data and data from the 2001 foot-and-mouth disease (FMD) epidemic in the U.K. Our results indicate that substantial computation savings can be obtained—albeit, of course, with some information loss—suggesting that such techniques may be of use in the analysis of very large epidemic data sets.  相似文献   

18.

Background

Chlamydia trachomatis is a common human pathogen that mediates disease processes capable of inflicting serious complications on reproduction. Aggressive inflammatory immune responses are thought to not only direct a person''s level of immunity but also the potential for immunopathology. With human immunobiology being debated as a cause of prevailing epidemiological trends, we examined some fundamental issues regarding susceptibility to multiple chlamydial infections that could have implications for infection spread. We argue that, compared to less-frequent exposure, frequent exposure to chlamydia may well produce unique immunobiological characteristics that likely to have important clinical and epidemiological implications.

Methods and Results

As a novel tool for studying chlamydia, we applied principles of modeling within-host pathogen dynamics to enable an understanding of some fundamental characteristics of an individual''s immunobiology during multiple chlamydial infections. While the models were able to reproduce shorter-term infection kinetics of primary and secondary infections previously observed in animal models, it was also observed that longer periods between initial and second infection may increase an individual''s chlamydial load and lengthen their duration of infectiousness. The cessation of short-term repeated exposure did not allow for the formation of long-lasting immunity. However, frequent re-exposure non-intuitively linked the formation of protective immunity, persistent infection, and the potential for immunopathology.

Conclusions

Overall, these results provide interesting insights that should be verified with continued study. Nevertheless, these results appear to raise challenges for current evidence of the development of long-lasting immunity against chlamydia, and suggest the existence of a previously unidentified mechanism for the formation of persistent infection. The obvious next goal is to investigate the qualitative impact of these results on the spread of chlamydia.  相似文献   

19.

Background

The prevalence of Sickle cell disease is extremely high in Democratic Republic of Congo. Despite this high prevalence of the disease, data on renal abnormalities in children are rare.

Method

The study proposed to assess blood pressure, glomerular function, urea and uric acid levels in 65 steady state Congolese children with homozygous sickle cell disease and 67 normal controls.

Results

In Hb-SS group, blood pressure level tended to be lower than Hb-AA groups but there was no statistically significant difference (p>0.05) between the two groups. The absolute values for GFR corrected for BSA were significantly higher in Hb-SS group compared to Hb-AA group (130.5±34.1 ml/min/1.73 m2 vs 113.7±24.5 ml/min/1.73 m2; p = 0.004). Children with Hb-SS were more likely to hyperfiltrate (30.8% of subjects) than children with Hb-AA (6.1% of subjects). Proteinuria was found in 4 (6.2%) children with Hb-SS. Uric acid level was significantly increased in children with Hb-SS compared to corresponding values in control group (4.4±1.3 mg/dl vs 3.5±1.1 mg/dl; p<0.001). Urea level was significantly decreased compared to corresponding values in Hb-AA group (15.3±8.3 mg/dl vs 22.9±10.1 mg/dl; p<0.001).

Conclusion

Hyperfiltration, low creatinine, lower urea and high uric acid are more common in children with sickle cell disease than in normal controls.  相似文献   

20.
One hundred patients with Parkinson''s disease were treated with levodopa for more than a year at UCLA Medical Center. They were examined at given intervals and their improvement was graded. The optimum therapeutic dose was attained by balancing side effects against relief of symptoms and ranged from 1.5 grams to 8.0 grams per day (average 4.3 grams). There is no doubt that levodopa is the most effective treatment now available for Parkinson''s disease. At the end of the first year, 60 percent of the patients improved 50 percent or better, and 10 percent were considered symptom-free. All major symptoms of this disease, including rigidity, akinesia and tremor, improved in variable degree.There were no serious abnormalities in the routine clinical laboratory tests. The comon side effects included nausea, vomiting and choreoathetoid dyskinesias. The side effects were not life threatening, but occasionally were major therapeutic challenges.Maximal benefits with minimal side effects were achieved only by careful adjustments of the levodopa dosage as the months went by. This needed careful management by the physician and cooperation by the patient. Anticholinergic medications or amantadine hydrochloride, sometimes both, usually supplemented the effect of the levodopa.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号