Functional Characterization of Allelic Variations of Human Cytochrome P450 2C8 (V181I, I244V, I331T, and L361F).

The human cytochrome P450 2C8 is responsible for the metabolism of various clinical drugs as well as endogenous fatty acids. Allelic variations can significantly influence the metabolic outcomes. In this study, we characterize the functional effects of four nonsynonymous single nucleotide polymorphisms *15, *16, *17, and *18 alleles recently identified in cytochrome P450 2C8. The recombinant allelic variant enzymes V181I, I244V, I331T, and L361F were successfully expressed in Escherichia coli and purified. The steady-state kinetic analysis of paclitaxel 6-hydroxylation revealed a significant reduction in the catalytic activities of the V181I, I244V, and L361F variants. The calculated catalytic efficiency (kcat/Km) of these variants was 5-26% of that of the wild-type enzyme. The reduced activities were due to both decreased kcat values and increased Km values of the variants. The epoxidation of arachidonic acid by the variants was analyzed. The L361F variant only exhibited 4-6% of the wild-type catalytic efficiency in ω-9- and ω-6-epoxidation reactions to produce 11,12-epoxyeicosatrienoic acid (EET) and 14,15-EET, respectively. These reductions were mainly due to a decrease in the kcat value of the L361F variant. The binding titration analysis of paclitaxel and arachidonic acid showed that all variants had similar affinities to those of the wild-type (10-14 µM for paclitaxel and 20-49 µM for arachidonic acid). The constructed paclitaxel docking model of the variant enzyme suggests that the L361F substitution leads to the incorrect orientation of paclitaxel in the active site, with the 6'C of paclitaxel displaced from the productive catalytic location. This study suggests that individuals carrying the newly identified P450 2C8 allelic variations are likely to have an altered metabolism of clinical medicines and production of fatty acid-derived signal molecules.

Caspase-6-cleaved tau is relevant in Alzheimer's disease and marginal in four-repeat tauopathies: Diagnostic and therapeutic implications.

AIM: Tau truncation (tr-tau) by active caspase-6 (aCasp-6) generates tau fragments that may be toxic. Yet the relationship between aCasp-6, different forms of tr-tau and hyperphosphorylated tau (p-tau) accumulation in human brains with Alzheimer's disease (AD) and other tauopathies remains unclear. METHODS: We generated two neoepitope monoclonal antibodies against tr-tau sites (D402 and D13) targeted by aCasp-6. Then, we used five-plex immunofluorescence to quantify the neuronal and astroglial burden of aCasp-6, tr-tau, p-tau and their co-occurrence in healthy controls, AD and primary tauopathies. RESULTS: Casp-6 activation was strongest in AD and Pick's disease (PiD) but almost absent in 4-repeat (4R) tauopathies. In neurons, the tr-tau burden was much more abundant in AD and PiD than in 4R tauopathies and disproportionally higher when normalising by p-tau pathology. Tr-tau astrogliopathy was detected in low numbers in 4R tauopathies. Unexpectedly, about half of tr-tau positive neurons in AD and PiD lacked p-tau aggregates, a finding we confirmed using several p-tau antibodies. CONCLUSIONS: Early modulation of aCasp-6 to reduce tr-tau pathology is a promising therapeutic strategy for AD and PiD but is unlikely to benefit 4R tauopathies. The large percentage of tr-tau-positive neurons lacking p-tau suggests that many vulnerable neurons to tau pathology go undetected when using conventional p-tau antibodies. Therapeutic strategies against tr-tau pathology could be necessary to modulate the extent of tau abnormalities in AD. The disproportionally higher burden of tr-tau in AD and PiD supports the development of biofluid biomarkers against tr-tau to detect AD and PiD and differentiate them from 4R tauopathies at a patient level.

Steroidogenic cytochrome P450 enzymes as drug target.

Human cytochrome P450 (CYP) enzymes are composed of 57 individual enzymes that perform monooxygenase activities. They have diverse physiological roles in metabolizing xenobiotics and producing important endogenous compounds, such as steroid hormones and vitamins. At least seven CYP enzymes are involved in steroid biosynthesis. Steroidogenesis primarily occurs in the adrenal glands and gonads, connecting each reaction to substrates and products. Steroids are essential for maintaining life and significantly contribute to sexual differentiation and reproductive functions within the body. Disorders in steroid biosynthesis can frequently cause serious health problems and lead to the development of diseases, such as prostate cancer, breast cancer, and Cushing's syndrome. In this review, we provide current updated knowledge on the major CYP enzymes involved in the biosynthetic process of steroids, with respect to their enzymatic mechanisms and clinical implications for the development of new drug candidates.

Structural Insights into the Interaction of Terpenoids with Streptomyces avermitilis CYP107P2.

Streptomyces avermitilis genome includes 33 genes encoding monooxygenation-catalyzing cytochrome P450 enzymes. We investigated the structure of CYP107P2 and its interactions with terpenoid compounds. The recombinant CYP107P2 protein was expressed in Escherichia coli and the purified enzyme exhibited a typical P450 spectrum upon CO-binding in its reduced state. Type-I substrate-binding spectral titrations were observed with various terpenoid compounds, including α-pinene, ß-pinene, α-terpinyl acetate, and (+)-3-carene. The calculated binding affinities (Kd) ranged from 15.9 to 50.8 µM. The X-ray crystal structure of CYP107P2 was determined at 1.99 Å resolution, with a well-conserved overall P450 folding conformation. The terpenoid compound docking models illustrated that the structural interaction between monoterpenes and CYP107P2, with the distance between heme and terpenes ranging from 3.4 to 5.4 Å, indicates potential substrate binding for P450 enzyme. This study suggests that CYP107P2 is a Streptomyces P450 enzyme capable of catalyzing terpenes as substrates, signifying noteworthy advancements in comprehending a novel P450 enzyme's involvement in terpene reactions.

Catalytic enhancements in cytochrome P450 2C19 by cytochrome b5.

Human cytochrome P450 2C19 catalyzes P450 enzyme reactions of various substrates, including steroids and clinical drugs. Recombinant P450 2C19 enzyme with histidine tag was successfully expressed in Escherichia coli and purified using affinity column chromatography. Ultra-performance liquid chromatography-tandem mass (UPLC-MS/MS) spectrometry showed that the purified P450 2C19 enzyme catalyzed 5-hydroxylation reaction of omeprazole. The purified enzyme displayed typical type I binding spectra to progesterone with a Kd value of 4.5 ± 0.2 µM, indicating a tight substrate binding. P450 2C19 catalyzed the hydroxylation of progesterone to produce 21-hydroxy (OH) as a major and 17-OH product as a minor product. Steady-state kinetic analysis of progesterone 21-hydroxylation indicated that the addition of cytochrome b5 stimulated a five-times catalytic turnover number of P450 2C19 with a kcat value of 1.07 ± 0.08 min-1. The molecular docking model of progesterone in the active site of P450 2C19 displayed that the 21-carbon of progesterone was located close to the heme with a distance of 4.7 Å, suggesting 21-hydroxylation of progesterone is the optimal reaction of P450 2C19 enzyme for a productive orientation of the substrate. Our findings will help investigate the extent to which cytochrome b5 affects the metabolism of P450 2C19 to drugs and steroids. Supplementary Information: The online version contains supplementary material available at 10.1007/s43188-023-00219-8.

Assessment of ChatGPT-4 in Family Medicine Board Examinations Using Advanced AI Learning and Analytical Methods: Observational Study.

Background: This research explores the capabilities of ChatGPT-4 in passing the American Board of Family Medicine (ABFM) Certification Examination. Addressing a gap in existing literature, where earlier artificial intelligence (AI) models showed limitations in medical board examinations, this study evaluates the enhanced features and potential of ChatGPT-4, especially in document analysis and information synthesis. Objective: The primary goal is to assess whether ChatGPT-4, when provided with extensive preparation resources and when using sophisticated data analysis, can achieve a score equal to or above the passing threshold for the Family Medicine Board Examinations. Methods: In this study, ChatGPT-4 was embedded in a specialized subenvironment, "AI Family Medicine Board Exam Taker," designed to closely mimic the conditions of the ABFM Certification Examination. This subenvironment enabled the AI to access and analyze a range of relevant study materials, including a primary medical textbook and supplementary web-based resources. The AI was presented with a series of ABFM-type examination questions, reflecting the breadth and complexity typical of the examination. Emphasis was placed on assessing the AI's ability to interpret and respond to these questions accurately, leveraging its advanced data processing and analysis capabilities within this controlled subenvironment. Results: In our study, ChatGPT-4's performance was quantitatively assessed on 300 practice ABFM examination questions. The AI achieved a correct response rate of 88.67% (95% CI 85.08%-92.25%) for the Custom Robot version and 87.33% (95% CI 83.57%-91.10%) for the Regular version. Statistical analysis, including the McNemar test (P=.45), indicated no significant difference in accuracy between the 2 versions. In addition, the chi-square test for error-type distribution (P=.32) revealed no significant variation in the pattern of errors across versions. These results highlight ChatGPT-4's capacity for high-level performance and consistency in responding to complex medical examination questions under controlled conditions. Conclusions: The study demonstrates that ChatGPT-4, particularly when equipped with specialized preparation and when operating in a tailored subenvironment, shows promising potential in handling the intricacies of medical board examinations. While its performance is comparable with the expected standards for passing the ABFM Certification Examination, further enhancements in AI technology and tailored training methods could push these capabilities to new heights. This exploration opens avenues for integrating AI tools such as ChatGPT-4 in medical education and assessment, emphasizing the importance of continuous advancement and specialized training in medical applications of AI.

The complete chloroplast genome sequences of six Hylotelephium species: Comparative genomic analysis and phylogenetic relationships.

To evaluate the phylogenetic relationships between Hylotelephium and Orostachys, and to provide important information for further studies, we analyzed the complete chloroplast genomes of six Hylotelephium species and compared the sequences to those of published chloroplast genomes of congeneric species and species of the closely related genus, Orostachys. The total chloroplast genome length of nineteen species, including the six Hylotelephium species analyzed in this study and the thirteen Hylotelephium and Orostachys species analyzed in previous studies, ranged from 150,369 bp (O. minuta) to 151,739 bp (H. spectabile). Their overall GC contents were almost identical (37.7-37.8%). The chloroplast genomes of the nineteen species contained 113 unique genes comprising 79 protein-coding genes (PCGs), 30 transfer RNA genes (tRNAs), and four ribosomal RNA genes (rRNAs). Among the annotated genes, fourteen genes contained one intron, and two genes contained two introns. The chloroplast genomes of the nineteen Hylotelephium and Orostachys species had identical structures. Additionally, the large single copy (LSC), inverted repeat (IR), and small single copy (SSC) junction regions were conserved in the Hylotelephium and Orostachys species. The nucleotide diversity between the Hylotelephium chloroplast genomes was extremely low in all regions, and only one region showed a high Pi value (>0.03). In all nineteen chloroplast genomes, six regions had a high Pi value (>0.03). The phylogenetic analysis showed that the genus delimitation could not be clearly observed even in this study because Hylotelephium formed a paraphyly with subsect. Orostachys of the genus Orostachys. Additionally, the data supported the taxonomic position of Sedum taqeutii, which was treated as a synonym for H. viridescens in previous studies, as an independent taxon.

Successful emergency medical service training with virtual field trips using video during the COVID-19 pandemic: the Official Development Assistance Project in Uzbekistan.

PURPOSE: The coronavirus disease 2019 pandemic saw many restrictions on the provision of emergency medical service (EMS) training through actual field trips (AFTs), requiring a search for alternatives. This study aimed to assess trainees' reactions to virtual field trips (VFTs) and determine the characteristics of instructional design for successful VFTs using edited videos and expert interviews. METHODS: This study evaluated Uzbekistan trainees' reactions to the VFT of EMS training using questionnaires in three categories: satisfaction, relevance, and engagement. Factors of satisfaction and dissatisfaction were identified through open-ended questions. RESULTS: A total of 286 trainees responded to the survey during 15 educational sessions conducted from 2020 to 2022. The trainees' responses to the VFT were positive. Overall mean scores were 4.65±0.49, 4.63±0.50, and 4.63±0.50 out of 5 points for satisfaction, relevance, and engagement, respectively. The trainees reported that the most interesting and helpful videos concerned the introduction of an EMS training curriculum and the observation of training facilities, such as the simulation centers of educational institutes. The leading causes of satisfaction were (1) authenticity of the VFTs, (2) easy-to-understand content, and (3) relevance to the job. The trainees suggested that Uzbek or Russian voice-overs would be better than subtitles in the video clip for focusing on VFT. CONCLUSION: In situations where AFTs are not available, VFTs using edited videos and expert interviews are a good alternative to EMS education. Based on these results, it is possible that AFTs could be replaced by VFTs using qualified videos with designed instructions as a distance learning method under specific conditions.

Psychosocial and Cultural Processes Underlying the Epidemiological Paradox within U.S. Latino Sexual Risk: A Systematic Review.

According to the epidemiological paradox, less acculturated Latina/o youth display fewer sexual risk behaviors. A systematic review was performed on psychosocial and cultural mechanisms potentially underlying the epidemiological paradox in sexual risk behaviors of U.S. Latina/o youth across acculturation measures (between January 2000 to October 2022). Thirty-five publications (n = 35) with forty-eight analyses of underlying mechanisms met the inclusion criteria. Thirty-one results from twenty-three publications found supporting evidence that one of the five factors was an underlying mechanism in the epidemiological paradox (n = 13 parenting practices, n = 4 peer influences, n = 4 familismo values, n = 4 religiosity, n = 6 traditional gender norms) as, generally protective, mediators or moderators in the link between acculturation and sexual risk behaviors. Studies varied in the sexual risk behavior examined and measurement of acculturation, but primarily employed cross-sectional designs and recruited samples through schools. Mechanisms that enhance close ties and unity of the family, such as those of familismo values and positive parenting, reduce the likelihood of sexual risk behaviors as Latina/o youth become more acculturated. Future directions are discussed which may provide guidance for risk prevention and intervention.

Experience of emergency medical services provider training using online training of trainers during COVID-19: official development assistance project in Tashkent, Uzbekistan.

OBJECTIVE: Since onsite education is difficult due to the COVID-19 pandemic, official development assistance (ODA) projects have implemented online training of trainers (ToT) for emergency medical experts and staff. This study aims to share and discuss the ToT experience and its results in Uzbekistan. METHODS: We trained emergency medical advanced course instructors through online ToT among emergency medical service experts in Uzbekistan as a part of an ODA project. After the ToT, instructors were selected based on written tests, video monitoring of practice, and simulation performance. They operated the emergency medical course including lectures, practices, and simulations for 5 days. We tested the trainees through written tests before and after the course. They were surveyed regarding the course contents, its relevance, and their satisfaction with the course. RESULTS: Six instructors were selected after the online ToT program. They educated 68 emergency medical workers through the three training courses. The total score of the pretest was 129.2±34.8, and the posttest score was 170.8±31.2, which was significantly higher (P<0.05). The satisfaction calculated by adding the values of survey items for this curriculum was 28.0 (interquartile range, 26.0-30.0), and there was no statistical difference regarding trainee satisfaction between the three courses (P=0.148). CONCLUSION: Instructors trained by online ToT programs could provide an in-person emergency medical advanced course.

Population Genomics Study and Implications for the Conservation of Zabelia tyaihyonii Based on Genotyping-By-Sequencing.

Zabelia tyaihyonii (Nakai) Hisauti and H. Hara is a perennial shrub endemic to Republic of Korea that grows naturally in only a very limited region of the dolomite areas of Gangwon-do and Chungcheongbuk-do Provinces in the Republic of Korea. Given its geographical characteristics, it is more vulnerable than more widely distributed species. Despite the need for comprehensive information to support conservation, population genetic information for this species is very scarce. In this study, we analyzed the genetic diversity and population structure of 94 individuals from six populations of Z. tyaihyonii using a genotyping-by-sequencing (GBS) approach to provide important information for proper conservation and management. Our results, based on 3088 single nucleotide polymorphisms (SNPs), showed a mean expected heterozygosity (He) of 0.233, no sign of within-population inbreeding (GIS that was close to or even below zero in all populations), and a high level of genetic differentiation (FST = 0.170). Analysis of molecular variance (AMOVA) indicated that the principal molecular variance existed within populations (84.5%) rather than among populations (17.0%). We suggested that six management units were proposed for conservation considering Bayesian structure analysis and phylogenetic analysis, and given the various current situations faced by Z. tyaihyonii, it is believed that not only the in situ conservation but also the ex situ conservation should be considered.

The complete chloroplast genome sequences of eight Orostachys species: Comparative analysis and assessment of phylogenetic relationships.

We analyzed the complete chloroplast genomes of eight Orostachys species and compared the sequences to those of published chloroplast genomes of the congeneric and closely related genera, Meterostachys and Hylotelephium. The total chloroplast genome length of thirteen species, including the eight species analyzed in this study and the five species analyzed in previous studies, ranged from 149,860 (M. sikokianus) to 151,707 bp (H. verticillatum). The overall GC contents of the genomes were almost identical (37.6 to 37.8%). The thirteen chloroplast genomes each contained 113 unique genes comprising 79 protein-coding genes, 30 tRNA genes, and four rRNA genes. Among the annotated genes, sixteen genes contained one or two introns. Although the genome structures of all Orostachys and Hylotelephium species were identical, Meterostachys differed in structure due to a relatively large gene block (trnS-GCU-trnS-GGA) inversion. The nucleotide diversity among the subsect. Orostachys chloroplast genomes was extremely low in all regions, and among the subsect. Appendiculatae, genus Orostachys, and all thirteen chloroplast genomes showed high values of Pi (>0.03) in one, five, or three regions. The phylogenetic analysis showed that Orostachys formed polyphyly, and subsect. Orostachys and Appendiculatae were clustered with Hylotelephium and Meterostachys, respectively, supporting the conclusion that each subsection should be considered as an independent genus. Furthermore, the data supported the taxonomic position of O. margaritifolia and O. iwarenge f. magnus, which were treated as synonyms for O. iwarenge in a previous study, as independent taxa. Our results suggested that O. ramosa and O. japonica f. polycephala were individual variations of O. malacophylla and O. japonica, respectively. The exact taxonomic position of O. latielliptica and the phylogenetic relationship among the three species, O. chongsunensis, O. malacophylla and O. ramosa, should be a topic of future study.