Screening library evolution through automation of solution preparation

The quality of the compound library is a critical success factor in every high-throughput screening campaign. Screening solutions have to be prepared with a high level of process control to ensure the correct identity and initial concentration of each compound. However, even under optimized storage conditions, a certain level of degradation in solution cannot be avoided. Therefore, regular quality control and eventual removal of solutions from the screening deck is necessary. Because solution preparation, especially the weighing of compounds, is a tedious and often manual task, a regular resolubilization of compounds is difficult to achieve. By complete automation of the solution preparation, the authors have laid the foundation for a life cycle management of screening solutions. They demonstrate how a combination of quality and process control leads to a continuous improvement of the screening library. In presenting an automation concept, they show how a series of innovative process optimizations led to a high-performance system that achieves full industrialization of solution preparation.     

微生物农药资源挖掘技术研究进展

微生物农药因其环境相容性受到了广泛重视。作为微生物农药研究开发的最早的环节,微生物农药资源的挖掘显得尤为重要。本文从基于生物活性、农药活性化合物及功能基因三个方面对微生物农药资源的快速挖掘技术进行了综述。针对不同的微生物农药产品开发目标,将以上技术进行整合,可实现微生物农药资源的快速挖掘,为微生物农药产业的发展提供丰富的资源,为微生物农药产业的发展提供支撑。     

On the prediction of statistical parameters in high-throughput screening using resampling techniques

A severe drawback in the high-throughput screening (HTS) process is the unintentional (random) presence of false positives and negatives. Their rates depend, among others, on the screening process being applied and the target class. Although false positives can be sorted out in subsequent process steps, their occurrence can lead to increased project cost. More fundamentally, it is not possible to rescue false nonhits. In this article, we investigate the prediction of the primary hit rate, hit confirmation rate, and false-positive and false-negative rates. Results for approximately 2800 compounds are considered that are tested as a pilot screen ahead of the primary screening work. This pilot screen is done at several concentrations and in replicates. The rates are predicted as a function of the proposed hit threshold by having the replicates serve as each other's confirmers, and confidence limits to the prediction are attached by means of a resampling scheme. A comparison of the rates resulting from the resampling with the primary hit rate and the confirmation rates obtained during the screening campaign shows how accurate this method is. Hence, the "optimal" compound concentration for the screen as well as the optimal hit threshold corresponding to low false rates can be determined prior to starting the subsequent screening campaign.     

Streamlining lead discovery by aligning in silico and high-throughput screening

Lead discovery in the pharmaceutical environment is largely an industrial-scale process in which it is typical to screen 1-5 million compounds in a matter of weeks using High Throughput Screening (HTS). This process is a very costly endeavor. Typically a HTS campaign of 1 million compounds will cost anywhere from $500000 to $1000000. There is consequently a great deal of pressure to maximize the return on investment by finding fast and more effective ways to screen. A panacea that has emerged over the past few years to help address this issue is in silico screening. In silico screening is now incorporated in all areas of lead discovery; from target identification and library design, to hit analysis and compound profiling. However, as lead discovery has evolved over the past few years, so has the role of in silico screening.     

Probing the primary screening efficiency by multiple replicate testing: a quantitative analysis of hit confirmation and false screening results of a biochemical assay

Despite a large body of references on assay development, assay optimization, strategies, and methodologies for high-throughput screening (HTS), there have been few reports on investigations of the efficiency of primary screening in a systematic and quantitative manner for a typical HTS process. Recently, the authors investigated the primary hit comparison and the effect of measurement variability by screening a library of approximately 25,000 random compounds in multiple replicate tests in a nuclear receptor recruitment assay with 2 different assay detection technologies. In this report, we utilized these sets of multiple replicate screening data from a different perspective and conducted a systematic data analysis in order to gain some insights into the hit-finding efficiency of a typical primary screening process. Specifically, hit confirmation, false-positive (declaration) rates, and false-negative rates at different hit cutoff limits were explored and calculated from the 2 different assay formats. Results and analyses provided some quantitative estimation regarding the reliability and efficiency of the primary screening process. For the 2 assay formats tested in this report, the confirmation rate (activity repeated at or above a certain hit limit) was found to be 65% or above. It was also suggested that, at least in this case, applying some hit-selection strategies, it is possible to decrease the number of false-negative or false-positive hits without significantly increasing the efforts in primary screening.     

A simulation study comparing the impact of experimental error on the performance of experimental designs and artificial neural networks used for process screening

Many variables and their interactions can affect a biotechnological process. Testing a large number of variables and all their possible interactions is a cumbersome task and its cost can be prohibitive. Several screening strategies, with a relatively low number of experiments, can be used to find which variables have the largest impact on the process and estimate the magnitude of their effect. One approach for process screening is the use of experimental designs, among which fractional factorial and Plackett–Burman designs are frequent choices. Other screening strategies involve the use of artificial neural networks (ANNs). The advantage of ANNs is that they have fewer assumptions than experimental designs, but they render black-box models (i.e., little information can be extracted about the process mechanics). In this paper, we simulate a biotechnological process (fed-batch growth of bakers yeast) to analyze and compare the effect of random experimental errors of different magnitudes and statistical distributions on experimental designs and ANNs. Except for the situation in which the error has a normal distribution and the standard deviation is constant, it was not possible to determine a clear-cut rule for favoring one screening strategy over the other. Instead, we found that the data can be better analyzed using both strategies simultaneously.     

Issues in newborn screening

Newborn screening aims at the earliest possible recognition of disorders so that intervention with effective treatment can prevent the most serious consequences of the disorder. However, of several thousand known genetic disorders, therapy is presently available for only a small proportion of them. Newborn screening was first applied to phenylketonuria (PKU). Presently, newborn screening programs have been implemented in 26 countries for different diseases. However, potential problems in newborn screening programs that make implementation of newborn screening programs difficult include quality assessment, concerns about professional and technical competence, and ethical considerations. It has been shown that in the process from sampling the newborn to reporting of the screening results most errors are made in the pre- and post-analytical phases. It appears that much more could be done for the fetus if genetic screening and diagnostics could be accomplished early in pregnancy rather than after birth.     

随机突变文库构建与筛选研究进展

定向进化是一个循环过程,在构建多样化基因序列和筛选功能基因变体之间交替进行.该技术目前已被广泛应用于DNA序列、基因功能和蛋白质结构的优化和分析.定向进化包括随机基因文库的生成、基因在合适宿主中的表达和突变文库的筛选.构建基因文库的关键是库容量和突变多样性,而筛选变体的关键是高灵敏度和高通量.文中讨论了定向进化技术的最...     

Protocols for cardiac differentiation of embryonic stem cells

Both mouse and human embryonic stem (ES) cells provide a powerful model of early cardiogenesis. Furthermore engineering of cardiac progenitors or cardiomyocytes from ES cells offers a tool for drug screening in toxicology or to search for molecules to improve and scale up the process of cardiac differentiation using high throughput screening technology. Spontaneous differentiation of ES cells into cardiomyocytes is however limited. Herein, I described simple protocols to commit both mouse and human ES cells toward a cardiac lineage and in turn to improve the process of in vitro differentiation.     

低场核磁共振技术快速检测小球藻油脂含量及其在高通量选育中的应用

为了建立一个高效的高产油微藻诱变育种流程,微藻中油脂含量快速和准确的测定在其中具有重要作用。在本研究中,首先利用低场核磁共振技术,建立了直接检测干藻粉和培养液中小球藻油脂含量的方法,其信号强度与细胞中油脂含量存在特异的线性关系,干藻粉和藻液中油脂含量与信号值拟合的R2均高于0.99,说明该方法用于小球藻油脂含量的检测是准确和可行的。同时该方法与传统油脂测量方法相比,具有快速、简便和准确等优点。但其通量不及尼罗红染色法,因此,我们开发了将尼罗红染色法用于初筛,低场核磁共振技术用于复筛的新型高通量藻种复合筛选方法,并将此筛选方法应用于一种异养高产油原壳小球藻的诱变育种过程中。首先从3 098株诱变藻种中初筛得到108株具有较高油脂含量的藻株,然后利用低场核磁共振技术复筛得到9株高产油性能的藻株,其中一株甘油三酯含量超过20%,比原始藻株提高1倍,培养168 h后培养液油脂浓度达到5 g/L,证明此诱变育种流程不仅提高了筛选的效率还可靠且可行。     

Searching for the most effective screening system to identify cell-active inhibitors of beta-secretase

The beta-secretase BACE1 is an attractive drug target for reducing the level of the Alzheimer's disease-promoting Abeta peptide in the brain. Whereas potent peptidomimetic in vitro inhibitors of BACE1 have been designed, screening approaches to identify cell-permeable small molecule inhibitors have had limited success so far. In the present minireview we summarize existing screening methods, discuss their scope of application in the drug discovery process and compare them to a novel cell-based screening system to identify BACE1 inhibitors by a positive yeast growth selection.     

Small Molecule Screening in Human Induced Pluripotent Stem Cell-derived Terminal Cell Types

A need for better clinical outcomes has heightened interest in the use of physiologically relevant human cells in the drug discovery process. Patient-specific human induced pluripotent stem cells may offer a relevant, robust, scalable, and cost-effective model of human disease physiology. Small molecule high throughput screening in human induced pluripotent stem cell-derived cells with the intent of identifying novel therapeutic compounds is starting to influence the drug discovery process; however, the use of these cells presents many high throughput screening development challenges. This technology has the potential to transform the way drug discovery is performed.     

Further comparison of primary hit identification by different assay technologies and effects of assay measurement variability

High-throughput screening (HTS) has grown rapidly in the past decade, with many advances in new assay formats, detection technologies, and laboratory automation. Recently, several studies have shown that the choice of assay technology used for the screening process is particularly important and can yield quite different primary screening outcomes. However, because the screening assays in these previous studies were performed in a single-point determination, it is not clear to what extent the difference observed in the screening results between different assay technologies is attributable to inherent assay variability and day-to-day measurement variation. To address this question, a nuclear receptor coactivator recruitment assay was carried out in 2 different assay formats, namely, AlphaScreen and time-resolved fluorescence resonance energy transfer, which probed the same biochemical binding events but with different detection technologies. For each assay format, 4 independent screening runs in a typical HTS setting were completed to evaluate the run-to-run screening variability. These multiple tests with 2 assay formats allow an unambiguous comparison between the discrepancies of different assay formats and the effects of the variability of assay and screening measurements on the screening outcomes. The results provide further support that the choice of assay format or technology is a critical factor in HTS assay development.     

Screening and self examination for breast cancer.

Breast cancer is the major form of cancer in women, with nearly 30,000 new cases and over 15,000 deaths in the United Kingdom each year. Breast screening by mammography has been shown in randomised trials to reduce mortality from breast cancer in women aged 50 and over. An NHS breast screening programme has been in operation in the United Kingdom since 1988. Its aim is to reduce mortality from breast cancer by 25% in the population of women invited to be screened. The uptake of mammography among the eligible population may be the single most important determinant if the programme is to be effective. Primary care teams have an important part to play in encouraging women to attend for screening and in providing information, advice, and reassurance at all stages of the screening process. To date, routine breast self examination has not been shown to be an effective method of screening for breast cancer and should not therefore be promoted as a primary screening procedure. There is, however, a case to be made for women to become more "breast aware."     

TOPSIS-Based Screening Method of Soil Remediation Technology for Contaminated Sites and its Application

A soil remediation technology screening system has not yet been established in China, and the existing supporting conditions for soil remediation technology cannot meet the supervision needs of contaminated sites’ remediation. Considering the soil remediation technology screening methods for contaminated sites in developed countries and the supervision requirements of contaminated sites in China, this article briefly introduces the main characteristics of decision-making methods, and the screening indices, including technical, economic, social, and environmental factors, are suggested. The technique for order performance by similarity to ideal solution (TOPSIS) was used to establish a screening process for soil remediation technology, and the analytic hierarchy process (AHP) method was utilized to obtain the weights of the screening indices. Tthe suggested screening method was then applied in a chromite ore-processing residue site in China, and suitable remediation technology (in-situ chemical reduction-oxidation) was proposed. The research results could provide scientific and technological support for the supervision of contaminated sites in China.     

Discovery of inhibitors of the pentein superfamily protein dimethylarginine dimethylaminohydrolase (DDAH), by virtual screening and hit analysis

An efficient process for the discovery of inhibitors of DDAH enzymes, without the requirement for high throughput screening, is described. Physicochemical filtering of a 308,000-compound library according to drug likeness followed by reciprocal nearest neighbour selection produced a representative subset of 35,000 compounds. Virtual screening on a dual processor PC using FlexX, followed by biological screening, identified two hit series. Similarity searches of commercial databases and chemical re-synthesis of pure compounds resulted in SR445 as an inhibitor of Pseudomonas aeruginosa DDAH at 2 microM.     

Targeting melanoma by small molecules: challenges ahead

Significant progress has been made in targeting melanoma using small molecule inhibitors, but challenges remain. Here we describe the history of screening approaches in melanoma and their limitations. We propose several approaches to refine our screening models to enhance the discovery process. It is hoped that this discussion will stimulate further improvements in our development of small molecules inhibitors for treatment of melanoma patients.     

Parental Decision-Making and Acceptance of Newborn Bloodspot Screening: An Exploratory Study

Objective

Newborn bloodspot screening is an internationally established public health measure. Despite this, there is a paucity of information relating to the decision-making process that parents go through when accepting newborn screening. This is important as screening panels are expanding; potentially leading to an increasing amount of complex information. This study sought to understand the factors that influence parental decisions and roles they play in the decision-making process.

Patients and Methods

Qualitative thematic evaluation of semi structured interviews with parents whose children had recently undergone newborn screening in the Merseyside and Cheshire region of England, UK.

Results

Eighteen interviews with first time parents (n = 12) and those with previous children (n = 6). Seven factors were identified as being either explicitly or implicitly related to parental decision-making: Experience, Attitudes to medicine, Information-seeking behaviour, Perceived knowledge, Attitudes to screening, and Perceived choice, all of which ultimately impact on Perceived decisional quality.

Conclusions

These results indicate that while content is important, other contextual factors such as personal experience, perceived choice, and general attitudes toward medicine, are also highly influential. In particular, relationships with key healthcare professionals are central to information collection, attitudes toward screening, and the level of deliberation that is invested in decisions to accept newborn bloodspot screening.