Development and validation of CYP26A1 inhibition assay for high-throughput screening.

All-trans retinoic acid (atRA) is an endogenous ligand of the retinoic acid receptors, which heterodimerize with retinoid X receptors. AtRA is generated in tissues from vitamin A (retinol) metabolism to form a paracrine signal and is locally degraded by cytochrome P450 family 26 (CYP26) enzymes. The CYP26 family consists of three subtypes: A1, B1, and C1, which are differentially expressed during development. This study aims to develop and validate a high throughput screening assay to identify CYP26A1 inhibitors in a cell-free system using a luminescent P450-Glo assay technology. The assay performed well with a signal to background ratio of 25.7, a coefficient of variation of 8.9%, and a Z-factor of 0.7. To validate the assay, we tested a subset of 39 compounds that included known CYP26 inhibitors and retinoids, as well as positive and negative control compounds selected from the literature and/or the ToxCast/Tox21 portfolio. Known CYP26A1 inhibitors were confirmed, and predicted CYP26A1 inhibitors, such as chlorothalonil, prochloraz, and SSR126768, were identified, demonstrating the reliability and robustness of the assay. Given the general importance of atRA as a morphogenetic signal and the localized expression of Cyp26a1 in embryonic tissues, a validated CYP26A1 assay has important implications for evaluating the potential developmental toxicity of chemicals.

Study on the evaluation and influencing factors of contracted residents on the coordination of primary medical institutions.

Background: The implementation of family doctor contract service is a pivotal measure to enhance primary medical services and execute the hierarchical diagnosis and treatment system. Achieving service coordination among various institutions is both a fundamental objective and a central element of contract services. Objective: The study aims to assess residents' evaluations and determining factors related to the coordination of health services within primary medical institutions across different regions of Shandong Province. The findings intend to serve as a reference for enhancing the coordination services offered by these institutions. Methods: The study employed a multi-stage stratified random sampling method to select three prefecture-level cities in Shandong Province with different economic levels. Within each city, three counties (districts) were randomly sampled using the same method. Within each county (district), three community health service centers and township health centers implementing family doctor contract services were selected randomly. Face-to-face questionnaire surveys were conducted with contracted residents using the coordination dimension of the revised Primary Care Assessment Tools Scale (PCAT) developed by the research team. Data analysis was conducted using such methods as one-way analysis of variance and multiple linear regression. Results: The sample included 3,859 contracted residents. The coordination dimension score of primary medical institutions averaged 3.41 ± 0.18, with the referral service sub-dimension scoring 3.60 ± 0.58 and the information system sub-dimension scoring 3.34 ± 0.65. The overall score of the referral service sub-dimension surpassed that of the information system sub-dimension. Regression results indicated that the city's economic status, the type of contracted institutions, gender, education, marital status, income, occupation, health status, and endowment insurance payment status significantly influenced the coordinated service score of primary medical institutions (p < 0.05). Conclusion: The coordination of primary medical institutions in Shandong Province warrants further optimization. Continued efforts should focus on refining the referral system, expediting information infrastructure development, enhancing the service standards of primary medical institutions, and fostering resident trust. These measures aim to advance the implementation of the hierarchical diagnosis and treatment and two-way referral system.

Cross-sectional study of factors affecting the receipt of mental health education in older migrants in China.

BACKGROUND: Population migration in China has increasingly included middle-aged and older populations. Relatedly, the lack of mental health education among China's older migrants is still an important but neglected problem. This study aimed to understand the current situation of mental health education received by the older migrant population in China and to explore related influencing factors. METHODS: This cross-sectional study included 5729 older migrants who participated in the 2017 China Migrants Dynamic Survey. The independent variables included four components: demographic and socioeconomic characteristics, migration factors, public health service utilization, and social integration factors. Data were analyzed using the chi-square test for single factors and a binary logistic regression model for multiple factors. RESULTS: A total of 1749 older migrants received mental health education, for a receipt rate of 30.53%. Regression analysis showed that older migrant individuals who had an average monthly household income > 3000 CNY, self-rated their health as healthy, had chronic diseases, had heard of National Basic Public Health Services, had established health records, received ≥2 types of health education were willing to integrate into the local population, and were highly involved in the community were more likely to receive mental health education. Older migrants who were ≥ 70 years old, had an elementary school education or below, had difficulties in the local community, had migrated ≥11 years prior, moved for their offspring, and moved across provinces were less likely to receive mental health education. CONCLUSIONS: The older migrant population does not receive sufficient mental health education. Mental health interventions should be tailored to the characteristics of older migrants to increase their mental health literacy and meet their psychological needs.

The status of emotional labour and its influence on job burnout among village doctors during the COVID-19 pandemic in China: a cross-sectional study.

BACKGROUND: Village doctors in China are not only the gatekeepers of rural residents' health but also the net bottom of the medical security system. However, emotional labour is increasingly threatening the stability of the rural primary medical system. In addition, the ongoing coronavirus disease 2019 (COVID-19) pandemic has further exposed the vulnerability of human resources in China's rural health system. This study aims to evaluate the current situation of emotional labour among village doctors and explore the impact of emotional labour on job burnout during the COVID-19 pandemic in China. METHODS: A cross-sectional survey was conducted in December 2021 in Shandong Province. We used structured questionnaires to collect data, including sociodemographic characteristics, emotional labour, and job burnout. Data were analysed by t test, analysis of variance (ANOVA), Pearson correlation analysis, and hierarchical multiple linear regression. RESULTS: A total of 1,093 village doctors from Shandong Province participated in the study. More than half of the participants were male (62.40%) and were between 41 and 50 years old (53.43%). The total mean score of emotional labour was 3.17 ± 0.67, of which the surface acting (SA) score was 2.28 ± 0.90, and the deep acting (DA) score was 3.91 ± 0.93. There were significant differences in SA according to gender and work content (P < 0.05) and in DA according to gender, age, education level, and work content (P < 0.05). Pearson correlation analysis showed that SA was positively correlated with job burnout (P < 0.001), and DA was negatively correlated with job burnout (P < 0.001). Hierarchical multiple linear regression analysis revealed that 29% of the variance in job burnout is attributable to SA (ß = 0.530, P < 0.001) and DA (ß = -0.154, P < 0.001). CONCLUSION: Village doctors in Shandong Province performed moderate levels of emotional labour during the COVID-19 pandemic. SA had a significant positive effect on job burnout, while DA had a significant negative effect on job burnout among village doctors. Administrators should enhance training on emotional labour for village doctors to play a positive role in alleviating their job burnout.

Evaluation and countermeasures of contracted services of Chinese family doctors from demanders' point of view - a case study of a city.

BACKGROUND: The "gatekeepers" for residents' health are their family doctors. The implementation of contracted services provided by family doctors is conducive to promoting hierarchical diagnosis and treatment and achieving the objective of providing residents comprehensive and full-cycle health services. Since its implementation in 2016, the contract service system for Chinese family doctors has yielded a number of results while also highlighting a number of issues that require further investigation. Consequently, the purpose of this study is to assess the impact of family doctors' contracted services in a Chinese city from the perspective of demanders (i.e., contracted residents), identify the weak links, and then propose optimization strategies. METHODS: In this study, a city in Shandong Province, China was selected as the sample city. In January 2020, 1098 contracted residents (including 40.5% men and 59.5% women) from 18 primary medical institutions (including township health centers and community health centers) were selected for on-site investigation. Take the PCAT-AS(Adult Short) scale revised in Chinese as the research tool to understand the medical experience of contracted residents in primary medical institutions, and interview some family doctors and residents to obtain more in-depth information. RESULTS: Among the four core dimensions of PCAT-AS, the score of Continuous was the highest (3.44 ± 0.58); The score of Coordinated was the lowest (3.08 ± 0.66); Among the three derived dimensions, the score of Family-centeredness was the highest (3.33 ± 0.65); The score of Culturally-competent was the lowest (2.93 ± 0.77). The types of contracting institutions, residents' age, marital status, occupation, and whether chronic diseases are confirmed are the influencing factors of PCAT scores. CONCLUSION: The family doctors' contracted services in the city has achieved certain results. At the same time, there are still some problems, such as difficult access to outpatient services during non-working hours, incomplete service items, an imperfect referral system, and inadequate utilization of traditional Chinese medicine services, it is recommended that the government continue to enhance and increase its investment in relevant policies and funds. Primary medical institutions should improve the compensation mechanism for family doctors and increase their work enthusiasm, improve and effectively implement the two-way referral system, gradually form an orderly hierarchical pattern of medical treatment, provide diversified health services in accordance with their own service capacity and the actual needs of residents, and improve the utilization rate of traditional Chinese medicine services in primary medical institutions.

Effect of healthcare system reforms on job satisfaction among village clinic doctors in China.

BACKGROUND: Village clinic doctors (VCDs) are part of the health service force in rural China. VCDs' job satisfaction (JS) is important to the stability of the three-tiered health service system. Since 2009, the Chinese government launched a new health care system reform (NHCSR) which affected VCDs significantly. This study aimed to analysing the effect of NHCSR on JS among VCDs. METHODS: All the data came from three surveys in Shandong Province conducted in 2012, 2015 and 2018. In 2012, an originally designed questionnaire was used to conduct a baseline survey of 405 VCDs from 27 townships in nine counties. In 2015 and 2018, 519 and 223 VCDs in the same counties were surveyed with the same questionnaire. Descriptive analysis and ANOVA were used to analyse the level and changes in VCDs' JS. RESULTS: The mean scores of VCDs' total JS were 2.664 ± 1.069, 3.121 ± 0.931 and 2.676 ± 1.044 in 2012, 2015 and 2018, respectively, with a significant difference (F = 28.732, P < 0.001). The mean scores of the medical practice environment and the job itself showed a continuous downward trend. The trends of the mean scores for job reward, internal work environment and organizational management were consistent with the trend for total JS. CONCLUSION: The NHCSR had a partly negative impact on VCDs' JS. Policy-makers should pay more attention to VCDs' job reward and medical practice environment. With the implementation of new reform policies, VCDs' JS should be the subject of more systematic and detailed research.

A direct capture method for purification and detection of viral nucleic acid enables epidemiological surveillance of SARS-CoV-2.

Studies have demonstrated that SARS-CoV-2 RNA can be detected in the feces of infected individuals. This finding spurred investigation into using wastewater-based epidemiology (WBE) to monitor SARS-CoV-2 RNA and track the appearance and spread of COVID-19 in communities. SARS-CoV-2 is present at low levels in wastewater, making sample concentration a prerequisite for sensitive detection and utility in WBE. Whereas common methods for isolating viral genetic material are biased toward intact virus isolation, it is likely that a relatively low percentage of the total SARS-CoV-2 RNA genome in wastewater is contained within intact virions. Therefore, we hypothesized that a direct unbiased total nucleic acid(TNA) extraction method could overcome the cumbersome protocols, variability and low recovery rates associated with the former methods. This led to development of a simple, rapid, and modular alternative to existing purification methods. In an initial concentration step, chaotropic agents are added to raw sewage allowing binding of nucleic acid from free nucleoprotein complexes, partially intact, and intact virions to a silica matrix. The eluted nucleic acid is then purified using manual or semi-automated methods. RT-qPCR enzyme mixes were formulated that demonstrate substantial inhibitor resistance. In addition, multiplexed probe-based RT-qPCR assays detecting the N1, N2 (nucleocapsid) and E (envelope) gene fragments of SARS-CoV-2 were developed. The RT-qPCR assays also contain primers and probes to detect Pepper Mild Mottle Virus (PMMoV), a fecal indicator RNA virus present in wastewater, and an exogenous control RNA to measure effects of RT-qPCR inhibitors. Using this workflow, we monitored wastewater samples from three wastewater treatment plants (WWTP) in Dane County, Wisconsin. We also successfully sequenced a subset of samples to ensure compatibility with a SARS-CoV-2 amplicon panel and demonstrated the potential for SARS-CoV-2 variant detection. Data obtained here underscore the potential for wastewater surveillance of SARS-CoV-2 and other infectious agents in communities.

COVID-19 Information Dissemination Using the WeChat Communication Index: Retrospective Analysis Study.

BACKGROUND: The COVID-19 outbreak has tremendously impacted the world. The number of confirmed cases has continued to increase, causing damage to society and the economy worldwide. The public pays close attention to information on the pandemic and learns about the disease through various media outlets. The dissemination of comprehensive and accurate COVID-19 information that the public needs helps to educate people so they can take preventive measures. OBJECTIVE: This study aimed to examine the dissemination of COVID-19 information by analyzing the information released by the official WeChat account of the People's Daily during the pandemic. The most-read COVID-19 information in China was summarized, and the factors that influence information dissemination were studied to understand the characteristics that affect its dissemination. Moreover, this was conducted in order to identify how to effectively disseminate COVID-19 information and to provide suggestions on how to manage public opinion and information governance during a pandemic. METHODS: This was a retrospective study based on a WeChat official account. We collected all COVID-19-related information, starting with the first report about COVID-19 from the People's Daily and ending with the last piece of information about lifting the first-level emergency response in 34 Chinese provinces. A descriptive analysis was then conducted on this information, as well as on Qingbo Big Data's dissemination index. Multiple linear regression was utilized to study the factors that affected information dissemination based on various characteristics and the dissemination index. RESULTS: From January 19 to May 2, 2020, the People's Daily released 1984 pieces of information; 1621 were related to COVID-19, which mainly included headline news items, items with emotional content, and issues related to the pandemic's development. By analyzing the dissemination index, seven information dissemination peaks were discerned. Among the three dimensions of COVID-19 information-media salience, content, and format-eight factors affected the spread of COVID-19 information. CONCLUSIONS: Different types of pandemic-related information have varying dissemination power. To effectively disseminate information and prevent the spread of COVID-19, we should identify the factors that affect this dissemination. We should then disseminate the types of information the public is most concerned about, use information to educate people to improve their health literacy, and improve public opinion and information governance.

Luminogenic D-Luciferin Derivatives as OATP1B1 and 1B3 Substrates in No-wash Assays.

The human hepatic organic ion transporting polypeptides OATP1B1 and -1B3 are uptake transporters that influence the disposition of several small molecule drugs and perpetrate certain adverse drug-drug interactions. To predict these in vivo effects, in vitro systems are used to screen new drug entities as potential transporter substrates or inhibitors. To simplify such studies, we synthesized luminogenic derivatives of the OATP1B1 and -1B3 substrate D-luciferin to test as probe substrates in a rapid, no-wash optical approach for substrate and inhibitor identification and characterization. Each derivative is a pro-luciferin containing a self-immolating trimethyl lock quinone linker that is sensitive to intracellular reducing environments that cause the release of free luciferin in proportion to the amount of probe taken up by the transporter. A subsequent luciferin-limited luciferase reaction produces light in proportion to transporter activity. We tested the derivatives in HEK293 cells that overexpress OATP1B1 or OATP1B3 by transient transfection or viral transduction. Derivatives were identified that showed OATP-dependent uptake that was time and concentration dependent, saturable and sensitive to inhibition by known OATP1B1 and -1B3 substrates and inhibitors. These luminogenic transporter probes enabled an add-only multi-well plate protocol suitable for automation and high throughput screening.

Evaluation of Luminogenic Substrates as Probe Substrates for Bacterial Cytochrome P450 Enzymes: Application to Mycobacterium tuberculosis.

Several cytochrome P450 enzymes (CYPs) encoded in the genome of Mycobacterium tuberculosis (Mtb) are considered potential new drug targets due to the essential roles they play in bacterial viability and in the establishment of chronic intracellular infection. Identification of inhibitors of Mtb CYPs at present is conducted by ultraviolet-visible (UV-vis) optical titration experiments or by metabolism studies using endogenous substrates, such as cholesterol and lanosterol. The first technique requires high enzyme concentrations and volumes, while analysis of steroid hydroxylation is dependent on low-throughput analytical methods. Luciferin-based luminogenic substrates have proven to be very sensitive substrates for the high-throughput profiling of inhibitors of human CYPs. In the present study, 17 pro-luciferins were evaluated as substrates for Mtb CYP121A1, CYP124A1, CYP125A1, CYP130A1, and CYP142A1. Luciferin-BE was identified as an excellent probe substrate for CYP130A1, resulting in a high luminescence yield after addition of luciferase and adenosine triphosphate (ATP). Its applicability for high-throughput screening was supported by a high Z'-factor and high signal-to-background ratio. Using this substrate, the inhibitory properties of a selection of known inhibitors could be characterized using significantly less protein concentration when compared to UV-vis optical titration experiments. Although several luminogenic substrates were also identified for CYP121A1, CYP124A1, CYP125A1, and CYP142A1, their relatively low yield of luminescence and low signal-to-background ratios make them less suitable for high-throughput screening since high enzyme concentrations will be needed. Further structural optimization of luminogenic substrates will be necessary to obtain more sensitive probe substrates for these Mtb CYPs.

Novel No-Wash Luminogenic Probes for the Detection of Transporter Uptake Activity.

Luminogenic probes were designed and synthesized for the detection of uptake transporter activity in a lytic cell-based assay. These probes rely on a self-cleavable trimethyl lock quinone-cyanobenzothiazole (TMQ-CNBT) or trimethyl lock quinone-luciferin (TMQ-Luc) linked to the anion transporter substrate fluorescein. Upon cellular transport, the TMQ is reduced by viable cells, resulting in the facile intramolecular lactonization and rapid release of the bioluminescent reporter molecule. The uptake transporter activity can then be detected without removing and washing off the extracellular substrates. Six probes were tested with OATP1B1*1a and OATP1B3 overexpressing HEK293 cells, and all compounds showed up to 10.2-fold enhancement in uptake when compared to control cells. Uptake of TMQ-luciferin compounds 2, 4, and 6 increased linearly over time up to 30 min at a concentration ranging from 40 nM to 20 µM. The apparent Km values obtained at different time intervals up to 30 min were nearly identical for a given compound, which validates the 30 min window as appropriate for uptake transporter assays. The average apparent Km values ranged from 0.3 to 0.8 µM and 0.2 to 1.3 µM for OATP1B1*1a and OATP1B3, respectively, indicating good affinities to these anion transporters. Furthermore, uptake of compound 2 was inhibited by two inhibitors of OATP1B1*1a and OATP1B3: rifampicin and ritonavir. The preliminary results obtained from compound 2 exhibited a time-dependent, saturatable, and inhibitable nature of uptake, indicating the feasibility of using the probe for the detection of a transporter-mediated process. This add-and-read homogeneous assay may provide a convenient, rapid, and facile way to detect changes in transporter activity in a high-throughput format, and this assay design strategy could create a new platform for a general cell uptake assay for biomaterials in the future.

Bioluminescent assays for ADME evaluation: dialing in CYP selectivity with luminogenic substrates.

INTRODUCTION: The cytochrome P450s (CYPs) are central to ADME studies because of their central role in drug metabolism. Proper CYP assay design and a correct understanding of CYP assay selectivity are critical for generating and interpreting biologically relevant data during drug development. Bioluminescent CYP assays use luminogenic probe substrates that have the unique property of producing photons in a second reaction with luciferase. AREAS COVERED: This article presents the general design principles for in vitro CYP assays. Specifically, the article focuses on the bioluminescent approach that couples CYP activity with photon production. EXPERT OPINION: Highly selective luminogenic substrates for CYP1A1, CYP1A2, CYP2C9, CYP3A4, CYP3A7, CYP4A and CYP4F have been developed with utility for interrogating the roles of these enzymes in biochemical and cell-based formats. These selective substrates are part of a larger collection of probes that deliver CYP inhibition and induction data that predict in vivo drug interactions. Furthermore, they support highly sensitive, rapid and scalable assays for cell-based and cell-free biochemical applications, which offer an alternative and often enabling option over conventional assay strategies.

Proluciferin acetals as bioluminogenic substrates for cytochrome P450 activity and probes for CYP3A inhibition.

Cytochrome P450 (P450) assays use probe substrates to interrogate the influence of new chemical entities toward P450 enzymes. We report the synthesis and study of a family of bioluminogenic luciferin acetal substrates that are oxidized by P450 enzymes to form luciferase substrates. The luciferin acetals were screened against a panel of purified P450 enzymes. In particular, one proluciferin acetal has demonstrated sensitive and selective CYP3A4-catalyzed oxidation to a luciferin ester-K(m) and k(cat) are 2.88 µM and 5.87 pmol metabolite · min(-1) · pmol enzyme(-1), respectively. The proluciferin acetal was used as a probe substrate to measure IC(50) values of known inhibitors against recombinant CYP3A4 or human liver microsomes. IC(50) values for the known inhibitors correlate strongly with IC(50) values calculated from the traditional high-performance liquid chromatography-based probe substrate testosterone. Luciferin acetals are rapidly oxidized to unstable hemi-orthoesters by CYP3A resulting in luciferin esters and, therefore, are conducive to simple rapid CYP3A bioluminescent assays.

[A novel analyzer of traditional Chinese medicines fingerprint].

The chromatographic fingerprint of traditional Chinese medicine is a way of comprehensive expression to show its complicated chemical composition. It is a generally-accepted method for analyzing the quality of traditional Chinese medicines. In this article, we address an analysis algorithm of traditional Chinese medicines fingerprint and its FPGA circuit method. With the use of a method based on combined GA training BP-NN, and by virtue of high-speed operation and parallel computing, the system is implemented successfully with FPGA which can be used in field control. The result shows that this is an efficient and superior method for use in the process of preparing raw Chinese medicines.

The use of a high-throughput luminescent method to assess CYP3A enzyme induction in cultured rat hepatocytes.

Assessment of a new chemical entity for cytochrome P450 (CYP) enzyme induction at an early stage in discovery is crucial to prevent potential drug-drug interactions. CYP3A, the most abundant CYP isoform in the liver, metabolizes approximately 50% of drugs currently on the market and is also a highly inducible enzyme. The use of both rat and human hepatocyte culture for the prediction of in vivo CYP3A induction has become refined and validated and is considered a standard in vitro model. The current evaluation of CYP3A enzyme induction involves the use of substrates requiring subsequent analysis of metabolites by high-performance liquid chromatography/mass spectrometry, which adds considerable time and cost. In the present study, we describe the use of a novel luminogenic substrate, luciferin-6'-pentafluoro-benzyl ether (PFBE), which allows for a fast and selective measurement of CYP3A enzyme induction in cultured rat hepatocytes. The extent of induction was evaluated using cells treated for 3 d with the prototypical inducers, dexamethasone, phenobarbital, and pregnenolone 16 alpha-carbonitrile (PCN). Enzyme activity was measured in the treated cells either by the depentafluorobenzylation of luciferin-PFBE or the testosterone 6-beta-hydroxylation. Using both methods, dexamethasone and PCN-treated cells exhibited strong CYP3A activity, whereas phenobarbital treatment resulted in a weak response. The fold induction varied between both methods, but this variability can be controlled by normalizing data from each treatment to a positive control. The results indicate that luciferin-PFBE is an attractive alternative to the use of conventional substrate, testosterone, providing a sensitive, robust, and rapid method compatible with the multiwell plate format for the assessment of CYP3A induction.

A homeodomain-zinc finger protein, ZFHX4, is expressed in neuronal differentiation manner and suppressed in muscle differentiation manner.

Human ZFHX4 has recently been shown to be a candidate gene for congenital bilateral isolated ptosis. Here, we report molecular cloning of the human ZFHX4 cDNA and genomic organization of this gene. Human ZFHX4 is about 180 kb long, containing 12 exons that encodes a 3599-amino acid protein carrying four homeodomains and 22 zinc fingers. The 11th exon is 3.2 kb in length and encodes all the four homeodomains together with four of the 22 zinc fingers. ZFHX4 is 90% homologous to mouse Zfhx4, 52% to human ATBF1A and 24% to Drosophila ZFH-2. ZFHX4 was mapped to human chromosome 8q13.3-q21.11 by fluorescence in situ hybridization using BAC clone RP11-48D4 as a probe. RT-PCR analysis showed that ZFHX4 transcripts were expressed in adult human brain, liver and muscle. This, together with the finding that Zfhx4 was expressed transiently in differentiating P19 embryonal carcinoma cells and C2C12 myoblasts, suggests that ZFHX4/Zfhx4 is involved in neural and muscle differentiation.

Luminogenic cytochrome P450 assays.

Luminogenic cytochrome P450 (CYP) assays couple CYP enzyme activity to firefly luciferase luminescence in a technology called P450-Glo(TM) (Promega). Luminogenic substrates are used in assays of human CYP1A1, -1A2, -1B1, -2C8, -2C9, -2C19, -2D6, -2J2, -3A4, -3A7, -4A11, -4F3B, -4F12 and -19. The assays detect dose-dependent CYP inhibition by test compounds against recombinant CYP enzymes or liver microsomes. Induction or inhibition of CYP activities in cultured hepatocytes is measured in a nonlytic approach that leaves cells intact for additional analysis. Luminogenic CYP assays offer advantages of speed and safety over HPLC and radiochemical-based methods. Compared with fluorogenic methods the approach offers advantages of improved sensitivity and decreased interference between optical properties of test compound and CYP substrate. These homogenous assays are sensitive and robust tools for high-throughput CYP screening in early drug discovery.