Transforming the delivery of care from "I" to "We" by developing the crisis resource management skills in pediatric interprofessional teams to handle common emergencies through simulation.

BACKGROUND: The healthcare system is highly complex, and adverse events often result from a combination of human factors and system failures, especially in crisis situations. Crisis resource management skills are crucial to optimize team performance and patient outcomes in such situations. Simulation-based training offers a promising approach to developing such skills in a controlled and realistic environment. METHODS: This study employed a mixed-methods (quantitative-qualitative) design and aimed to assess the effectiveness of a simulation-based training workshop in developing crisis resource management skills in pediatric interprofessional teams at a tertiary care hospital. The effectiveness of the intervention was evaluated using Kirkpatrick's Model, focusing on reaction and learning levels, employing the Collaboration and Satisfaction about Care Decisions scale, Clinical Teamwork Scale, and Ottawa Global Rating Scale for pre- and post-intervention assessments. Focused group discussions were conducted with the participants to explore their experiences and perceptions of the training. RESULTS: Thirty-nine participants, including medical students, nurses, and residents, participated in the study. Compared to the participants' pre-workshop performance, significant improvements were observed across all measured teamwork and performance components after the workshop, including improvement in scores in team communication (3.16 ± 1.20 to 7.61 ± 1.0, p < 0.001), decision-making (3.50 ± 1.54 to 7.16 ± 1.42, p < 0.001), leadership skills (2.50 ± 1.04 to 5.44 ± 0.6, p < 0.001), and situation awareness (2.61 ± 1.13 to 5.22 ± 0.80, p < 0.001). No significant variations were observed post-intervention among the different teams. Additionally, participants reported high levels of satisfaction, perceived the training to be highly valuable in improving their crisis resource management skills, and emphasized the importance of role allocation and debriefing. CONCLUSIONS: The study underscores the effectiveness of simulation-based training in developing crisis resource management skills in pediatric interprofessional teams. The findings suggest that such training can impact learning transfer to the workplace and ultimately improve patient outcomes. The insights from our study offer additional valuable considerations for the ongoing refinement of simulation-based training programs. There is a need to develop more comprehensive clinical skills evaluation methods to better assess the transferability of these skills in real-world settings. The potential challenges unveiled in our study, such as physical exhaustion during training, must be considered when refining and designing such interventions.

Recent Developments in Mutation Enrichment and Detection Technologies.

BACKGROUND: Presence of excess unaltered, wild-type DNA (wtDNA) providing information of little clinical value may often mask low-level mutations containing important diagnostic or therapeutic clues. This is a recurring hurdle in biotechnology and medicine, including cancer, prenatal diagnosis, infectious diseases, and organ transplantation. Mutation enrichment techniques that allow reduction of unwanted DNA to enable the detection of low-level mutations have emerged since the early 1990s. They are continuously being refined and updated with new technologies. The burgeoning interest in liquid biopsies for residual cancer monitoring, detection of resistance to therapy, and early cancer detection has driven an expanded interest in new and improved methodologies for practical and effective mutation enrichment and detection of low-level mutations of clinical relevance. CONTENT: Newly developed mutation enrichment technologies are described and grouped according to the main principle of operation, PCR-blocking technologies, enzymatic methods, and physicochemical approaches. Special emphasis is given to technologies enabling pre-PCR blockage of wtDNA to bypass PCR errors [nuclease-assisted minor-allele enrichment assay with overlapping probes (NaME-PrO) and UV-mediated cross-linking minor allele enrichment (UVME)] or providing high multiplexity followed by next-generation sequencing [Minor allele enriched sequencing through recognition oligonucleotides (MAESTRO)]. SUMMARY: This review summarizes technological developments in rare mutation enrichment over the last 12 years, complementing pre-2010 reviews on this topic. The expanding field of liquid biopsy calls for improved limits of detection (LOD) and highly parallel applications, along with the traditional requirements for accuracy, speed, and cost-effectiveness. The current technologies are reviewed with regards to these new requirements.

Repurposing Melanoma Chemotherapy to Activate Inflammasomes in the Treatment of BRAF/MAPK Inhibitor Resistant Melanoma.

The development of resistance to treatments of melanoma is commonly associated with an upregulation of the MAPK pathway and the development of an undifferentiated state. Previous studies have suggested that melanoma with these resistance characteristics may be susceptible to innate death mechanisms such as pyroptosis triggered by the activation of inflammasomes. In this study, we have taken cell lines from patients before and after the development of resistance to BRAF V600 inhibitors and exposed the resistant melanoma to temozolomide (a commonly used chemotherapy) with and without chloroquine to inhibit autophagy. It was found that melanoma with an inflammatory undifferentiated state appeared susceptible to this combination when tested in vitro and in vivo against xenografts in nonobese diabetic scid gamma mice. Translation of the latter results into patients would promise durable responses in patients treated by the combination. The inflammasome and death mechanism involved appeared to vary between melanoma and involved either AIM2 or NLRP3 inflammasomes and gasdermin D or E. These preliminary studies have raised questions as to the selectivity for different inflammasomes in different melanoma and their selective targeting by chemotherapy. They also question whether the inflammatory state of melanoma may be used as biomarkers to select patients for inflammasome-targeted therapy.

Air Temperature Reductions at the Base of Tree Canopies.

Trees in urban settings have a significant role in regulating urban hydrologic cycles. Urban trees, either as standalone plantings or as part of a tree pit, are an increasingly popular stormwater management tool. Beyond their aesthetic contribution to urban environments, trees are widely accepted as reducing the ambient air temperature. However, there is limited long-term quantitative information regarding the temperature mitigation performed by urban trees through the use of temperature sensors over a large urban area. This study monitored air temperature at locations throughout the city of Camden, New Jersey. Sensors were installed under canopies of trees of different sizes throughout the city using a statistical experimental design. The tree size (small or large) and canopy (intersecting or nonintersecting), along with the street orientation (predominantly north-south or east-west) and time of day (daylight, nighttime, or full-day), were experimental design factors. Sensors attached to poles along the streets or in parking lots served as controls. This study recorded temperatures at 10-min intervals from early August through late November 2017 using logging thermistors mounted in radiation shields about 4 m above the ground surface. Using the maximum daily air temperature at control sites, all temperature data were categorized into three groups of hot, average, and cool days. The groups were analyzed separately using the analysis of variance to test the significance of the categorical variables. During hot days (a maximum temperature larger than 30°C), there was a meaningful statistical difference between recorded mean air temperatures under trees with intersecting canopies and the control sites. A categorical analysis of street orientation for hot and average days showed that during the daytime, east-west streets were hotter than north-south streets, while this trend reversed at night when north-south streets were hotter than east-west streets. For cool days, there were no differences for the studied categorical factors.

A Combination of Epigenetic BET and CDK9 Inhibitors for Treatment of Human Melanoma.

Dysregulation of epigenetic modifiers is a frequent event in melanoma and underlies many aspects of melanoma biology, including resistance to targeted therapy and immunotherapies. Here, we report that dual targeting of BET and CDK9 proteins have synergistic effects against melanoma cells in vitro and in vivo. The BET inhibitor (IBET151) and CDK9 inhibitor (CDKI73) synergistically killed melanoma cells in vitro independent of their BRAF or NRAS mutation status. The combination of drugs markedly inhibited the growth of human melanoma C002M cells in vitro in three-dimensional spheroids and in vivo in NOD-SCID gamma mice compared with vehicle control and the individual drugs (P < 0.05). Cell death was associated with mitochondrial depolarization, caspase-dependent apoptosis with cleavage of PARP1, and downregulation of anti-apoptotic proteins BCL2, BCLXL, and MCL1. Gene set enrichment analysis revealed downregulation of hallmark gene sets associated with E2F, G2M checkpoint, and c-MYC. Survival analysis showed worse prognosis with high G2M, E2F, or c-MYC gene signatures, suggesting biomarkers of response of BET and CDK9 inhibitors in melanoma. This combination of epigenetic inhibitors targets multiple downstream genes, leading to cell death of melanoma cells in vitro and in vivo, and warrants further investigation for treatment of melanoma in patients not responding to current therapies.

Tree box performance in exfiltrating stormwater runoff.

This study determines the exfiltration rates in six tree boxes with embedded sensors and analyzes their hydrologic performance for 2 years to quantify the effect of different parameters (i.e., water depth, temperature, and age) on the exfiltration rate. Each tree box is 1.5 m wide, 1.5 m long, and 1.8 m deep. A 46-cm-diameter shaft was drilled at the bottom of each tree box to reach the underlying permeable soil layer. The water level inside the shaft rose up to 500 cm. Exfiltration rate increased with water level and exfiltration rate in second year decreased significantly by 27%-37% compared with first year. Overall, in the second year, the decrease in geometric mean exfiltration rate was largest for moderate depths of the standing water inside the shaft, ranging between 100 and 130 cm from the bottom of the shaft. The exfiltration rate of the tree boxes was significantly larger for warmer season and significantly smaller for cooler season. The infiltration rate of the underlying soil is a controlling factor of the performance of tree box. PRACTITIONER POINTS: The study determines the exfiltration rates in six tree boxes and analyzes their performance over time. Exfiltration rate in second year decreased significantly by 27%-37% compared to first year. The exfiltration rate of the tree boxes was larger for warmer rain events and smaller for cooler rain events. Tree boxes with lower permeable underlying soil developed higher water level in the shaft.

Monitoring infiltration rates with time domain reflectometers.

The current study determines infiltration rates in six tree boxes located in Louisville, KY, and analyzes the effects of season, age of the tree box, and depth on infiltration. Street and parking lot runoff enter each tree box through a curb cut. Time domain reflectometers (TDRs) were embedded in the tree box media at different depths to continuously monitor volumetric soil moisture content and other parameters. The moisture content recorded by the TDRs was used to calculate steady-state infiltration rates through the media at the TDR location using the Green-Ampt equation. For each rain event, steady-state infiltration rate and drainage rate were separately calculated. For four of the six tree boxes, the steady-state infiltration rate did not vary with depth. However, the drainage rate varied with depth for five of the six tree boxes. Overall, the drainage rate through the entire depth is 1.7 times larger than in the upper layer. During the second year of the study, the steady-state infiltration rate and drainage rate decreased by 20% and 38%, respectively, from the first year. The steady-state infiltration rate and drainage rate vary with seasons. Some correlation (r = -0.5) was observed between initial soil moisture content and steady-state infiltration rate. PRACTITIONER POINTS: Initial infiltration rate and drainage rate decrease by 20% and 30%, respectively, within a year. The smallest infiltration rates were observed during winter and largest infiltration rates were observed in summer. Initial and saturated infiltration rates varied among all six tree boxes.

Commonly integrated epigenetic modifications of differentially expressed genes lead to adaptive resistance in cancer.

Aim: To investigate the integrated epigenetic regulation of acquired drug resistance in cancer. Materials & methods: Our gene expression data of five induced drug-tolerant cell models, one resistant cell line and one publicly available drug-resistant dataset were integrated to identify common differentially expressed genes and pathways. ChIP-seq and DNA methylation by HM450K beadchip were used to study the epigenetic profile of differential expressed genes. Results & conclusion: Integrated transcriptomic analysis identified a common 'viral mimicry' related gene signature in induced drug-tolerant cells and the resistant state. Analysis of the epigenetic regulation revealed a common set of down-regulated genes, which are marked and regulated by a concomitant loss of H3K4me3, gain of H3K9me3 and increment of regional DNA methylation levels associated with tumor suppressor genes and apoptotic signaling.

Magnolol induces cell death through PI3K/Akt-mediated epigenetic modifications boosting treatment of BRAF- and NRAS-mutant melanoma.

Most BRAF-mutant melanoma patients experience a fulminate relapse after several months of treatment with BRAF/MEK inhibitors. To improve therapeutic efficacy, natural plant-derived compounds might be considered as potent additives. Here, we show that magnolol, a constituent of Magnolia officinalis, induced G1 arrest, apoptosis and cell death in BRAF- and NRAS-mutant melanoma cells at low concentration, with no effect in BRAF- and NRAS wild-type melanoma cells and human keratinocytes. This was confirmed in a 3D spheroid model. The apoptosis-inducing effect of magnolol was completely rescued by activating Akt suggesting a mechanism relying primarily on Akt signaling. Magnolol significantly downregulated the PI3K/Akt pathway which led to a global decrease of the active histone mark H3K4me3. Alongside, the repressive histone mark H3K9me3 was increased as a response to DNA damage. Magnolol-induced alterations of histone modifications are reversible upon activation of the Akt pathway. Magnolol-induced a synergistic effect in combination with either BRAF/MEK inhibitors dabrafenib/trametinib or docetaxel at a lower concentration than usually applied in melanoma patients. Combination of magnolol with targeted therapy or chemotherapy also led to analogous effects on histone marks, which was rescued by Akt pathway activation. Our study revealed a novel epigenetic mechanism of magnolol-induced cell death in melanoma. Magnolol might therefore be a clinically useful addition to BRAF/MEK inhibitors with enhanced efficacy delaying or preventing disease recurrence.

Urban Stormwater Characterization, Control and Treatment.

A review of literature related to stormwater runoff characterization and its subsequent management and treatment from 2017 was conducted. The 250 articles summarized herein are organized along three central themes: (1) stormwater quality and quantity characteristics, (2) site-scale stormwater management practices, with a focus on low impact development (LID) and green infrastructure (GI), and (3) watershed-scale performance of stormwater controls. Within each section, common research themes and future work are highlighted.

Microenvironment-Driven Dynamic Heterogeneity and Phenotypic Plasticity as a Mechanism of Melanoma Therapy Resistance.

Drug resistance constitutes a major challenge in designing melanoma therapies. Microenvironment-driven tumor heterogeneity and plasticity play a key role in this phenomenon. Melanoma is highly heterogeneous with diverse genomic alterations and expression of different biological markers. In addition, melanoma cells are highly plastic and capable of adapting quickly to changing microenvironmental conditions. These contribute to variations in therapy response and durability between individual melanoma patients. In response to changing microenvironmental conditions, like hypoxia and nutrient starvation, proliferative melanoma cells can switch to an invasive slow-cycling state. Cells in this state are more aggressive and metastatic, and show increased intrinsic drug resistance. During continuous treatment, slow-cycling cells are enriched within the tumor and give rise to a new proliferative subpopulation with increased drug resistance, by exerting their stem cell-like behavior and phenotypic plasticity. In melanoma, the proliferative and invasive states are defined by high and low microphthalmia-associated transcription factor (MITF) expression, respectively. It has been observed that in MITFhigh melanomas, inhibition of MITF increases the efficacy of targeted therapies and delays the acquisition of drug resistance. Contrarily, MITF is downregulated in melanomas with acquired drug resistance. According to the phenotype switching theory, the gene expression profile of the MITFlow state is predominantly regulated by WNT5A, AXL, and NF-κB signaling. Thus, different combinations of therapies should be effective in treating different phases of melanoma, such as the combination of targeted therapies with inhibitors of MITF expression during the initial treatment phase, but with inhibitors of WNT5A/AXL/NF-κB signaling during relapse.

Depression and Quality of Life among Postmenopausal Women in Bangladesh: A Cross-sectional Study.

OBJECTIVES: The aims of the research are to examine the problems of abnormal menopausal women: the relationship between depression and menopausal-specific quality of life (MENQOL)-symptoms among postmenopausal women; the association of MENQOL-symptoms between pre- and postmenopausal female society in Bangladeshi real community. METHODS: This cross sectional study was conducted on 435 women of Tangail, aged (≥ 17) years, using a structured questionnaire where is inaacluded the information of MENQOL and one of the main outcomes "depression" is measured by beck depression inventory. RESULTS: Menopausal status and MENQOL symptoms (except pain) are significantly (P < 0.05) associated. By using post-hoc analysis, the proportion of menopausal women, classified as having a depressive mood of early menopause is significantly higher than natural-menopause. Among postmenopausal women, there is a significant correlation between "concentration problem" and "depression". Here mean depression score (29.40 ± 6.42) of menopausal women who have any difficulty in concentrating is higher than mean depression score (20.89 ± 6.64) of menopausal women who have no difficulty in concentrating. Another six factors (osteoporosis, heart-beating, fatigue, pressure, tingling, headaches) of MENQOL-symptoms were significantly correlated with depression and P-values are 0.000, 0.000, 0.000, 0.033, 0.006, and 0.002, respectively. Finally the presence of "difficulty in concentrating" and "fatigue" are strongly associated factors with depression score (P < 0.001). CONCLUSIONS: The early postmenopausal women have to face more psychological problems (e.g., depression) compare to others. Among postmenopausal women, there is no significant relation between depression and vasomotor symptom (e.g., hot-flashes) perspective to menopausal female society of Bangladesh.

Assessment of Menopausal Symptoms among Early and Late Menopausal Midlife Bangladeshi Women and Their Impact on the Quality of Life.

OBJECTIVES: Every physical abnormal criterion has an impact on the health. Late menopause causes different physiological problems which alike early menopause. The research interest is associated with both early and late menopausal women of Bangladesh as only few menopausal studies available in South East Asia especially in Bangladesh. The aims of this study are not only to assess the symptoms of menopausal abnormality but also to determine the impact of these symptoms on the quality of life (QOL) of the female society in Bangladesh. METHODS: Data mining techniques are used to rank the 22 factors (conducted with questionnaire) commonly associated with menopause. Among the participants menstruation that stops before 45 years was considered as early menopausal status and after 50 years as late menopausal. The mean of age and mean length of time in years, since menopause for all participants were 61.55±10.7 and 14.13±11.17, respectively. Recorded data indicated 67% were early menopausal women and 33% were late menopausal women. RESULTS: Results indicated that feeling tired or lacking in energy and dizziness (83%) and depression (82%) have worst impact on QOL among all factors, respectively. The next prevalent symptoms included hot flashes (64%), osteoporosis (72%), sweating at night (63%), concentration problem (75%), irritability (63%), feeling tense (77%), headache (66%). However, less frequent factors included breathing problems (33%), loss of feeling (31%), coherent heart disease (13%) and type2 diabetics (9%). CONCLUSION: Our study indicates that early menopausal women are facing more physiological problems than the late menopausal women on their QOL.

Imaging- and Flow Cytometry-based Analysis of Cell Position and the Cell Cycle in 3D Melanoma Spheroids.

Three-dimensional (3D) tumor spheroids are utilized in cancer research as a more accurate model of the in vivo tumor microenvironment, compared to traditional two-dimensional (2D) cell culture. The spheroid model is able to mimic the effects of cell-cell interaction, hypoxia and nutrient deprivation, and drug penetration. One characteristic of this model is the development of a necrotic core, surrounded by a ring of G1 arrested cells, with proliferating cells on the outer layers of the spheroid. Of interest in the cancer field is how different regions of the spheroid respond to drug therapies as well as genetic or environmental manipulation. We describe here the use of the fluorescence ubiquitination cell cycle indicator (FUCCI) system along with cytometry and image analysis using commercial software to characterize the cell cycle status of cells with respect to their position inside melanoma spheroids. These methods may be used to track changes in cell cycle status, gene/protein expression or cell viability in different sub-regions of tumor spheroids over time and under different conditions.

Score based risk assessment of lung cancer and its evaluation for Bangladeshi people.

BACKGROUND: The problem of cancer, especially lung cancer, is very acute in Bangladesh. The present study was conducted to evaluate the risk of lung cancer among Bangladeshi people based on hereditary, socio-economic and demographic factors. MATERIALS AND METHODS: This study was carried out in 208 people (patients-104, controls-104) from January 2012 to September 2013 using a structured questionnaire containing details of lung cancer risk factors including smoking, secondhand smoke, tobacco leaf intake, age, gender, family history, chronic lung diseases, radiotherapy in the chest area, diet, obesity, physical activity, alcohol consumption, occupation, education, and income. Descriptive statistics and testing of hypotheses were used for the analysis using SPSS software (version 20). RESULTS: According to this study, lung cancer was more prevalent in males than females. Smoking was the highest risk factor (OR=9.707; RR=3.924; sensitivity=0.8872 and P<0.0001) followed by previous lung disease (asthma, tuberculosis etc.) (OR=7.095; RR=1.508; sensitivity=0.316 and P<0.0001)) for male patients. Highly cooked food (OR=2.485; RR=1.126; sensitivity=0.418 and P=0.004)) and also genetic inheritance (OR=1.93; RR=1.335; sensitivity=0.163 and P=0.138) demonstrated significant correlation with lung cancer as risk factors after these two and alcohol consumption was not prevalent. On the other hand, for female patients, tobacco leaf intake represented the highest risk (OR=2.00; RR=1.429; sensitivity= 0.667 and P=0.5603) while genetic inheritance and highly cooked food also correlate with lung cancer but not so significantly. Socio- economic status and education level also play important roles in causing lung cancer. Some 78.5% male and 83.3% of female cancer patients were rural residents, while 58.2% lived at the margin or below the poverty line. Most male (39.8%) and female (50.0%) patients had completed only primary level education, and 27.6% male and 33.3% female patients were illiterate. Smoking was found to be more prevalent among the less educated persons. CONCLUSIONS: The results obtained in this study indicate the importance of creating awareness about lung cancer risk factors among Bangladeshi people and making appropriate access to health services for the illiterate, poor, rural people.

Early detection of lung cancer risk using data mining.

BACKGROUND: Lung cancer is the leading cause of cancer death worldwide Therefore, identification of genetic as well as environmental factors is very important in developing novel methods of lung cancer prevention. However, this is a multi-layered problem. Therefore a lung cancer risk prediction system is here proposed which is easy, cost effective and time saving. MATERIALS AND METHODS: Initially 400 cancer and non-cancer patients' data were collected from different diagnostic centres, pre-processed and clustered using a K-means clustering algorithm for identifying relevant and non-relevant data. Next significant frequent patterns are discovered using AprioriTid and a decision tree algorithm. RESULTS: Finally using the significant pattern prediction tools for a lung cancer prediction system were developed. This lung cancer risk prediction system should prove helpful in detection of a person's predisposition for lung cancer. CONCLUSIONS: Most of people of Bangladesh do not even know they have lung cancer and the majority of cases are diagnosed at late stages when cure is impossible. Therefore early prediction of lung cancer should play a pivotal role in the diagnosis process and for an effective preventive strategy.

Attenuation and protective efficacy of an O-antigen-deficient mutant of Francisella tularensis LVS.

Francisella tularensis is a zoonotic, Gram-negative coccobacillus that causes tularemia in humans and animals. F. tularensis subspecies tularensis (type A) and F. tularensis subspecies holarctica (type B) are antigenically similar and more virulent than Francisella novicida in humans. The genetic locus that encodes the LPS O antigen was found to be substantially different between the type B live vaccine strain (LVS) and F. novicida. One LVS-specific gene with homology to a galactosyl transferase was selected for allelic replacement using a sacB-chloramphenicol expression suicide plasmid, and recombinants were screened for colony morphology on Congo red agar that matched that of F. novicida. Two mutants (WbtI(S187Y) and WbtI(G191V)) were isolated that contained substitutions in conserved motifs in the sugar transamine/perosamine synthetase (WbtI) of the O-antigen locus, and the latter mutant was extensively tested and characterized. WbtI(G191V) grew at the same rate as the parent strain in Chamberlain's defined medium, completely lacked O antigen, was serum-sensitive but could grow in a mouse macrophage cell line, had increased resistance to sodium deoxycholate, and was highly attenuated in mice. Complementation of WbtI(G191V) with the wild-type wbtI gene in trans restored normal LPS synthesis, phenotypic properties similar to the parent, and virulence in mice. Immunization with WbtI(G191V) protected mice against a relatively low-dose intraperitoneal challenge with LVS, but was less protective against a high-dose challenge. These results indicate that complete loss of O antigen alters the surface phenotype and abrogates virulence in F. tularensis, but also compromises the induction of full protective immunity against F. tularensis infection in mice.

Functional diversity of the rhodanese homology domain: the Escherichia coli ybbB gene encodes a selenophosphate-dependent tRNA 2-selenouridine synthase.

Escherichia coli has eight genes predicted to encode sulfurtransferases having the active site consensus sequence Cys-Xaa-Xaa-Gly. One of these genes, ybbB, is frequently found within bacterial operons that contain selD, the selenophosphate synthetase gene, suggesting a role in selenium metabolism. We show that ybbB is required in vivo for the specific substitution of selenium for sulfur in 2-thiouridine residues in E. coli tRNA. This modified tRNA nucleoside, 5-methylaminomethyl-2-selenouridine (mnm(5)se(2)U), is located at the wobble position of the anticodons of tRNA(Lys), tRNA(Glu), and tRNA(1)(Gln). Nucleoside analysis of tRNAs from wild-type and ybbB mutant strains revealed that production of mnm(5)se(2)U is lost in the ybbB mutant but that 5-methylaminomethyl-2-thiouridine, the mnm(5)se(2)U precursor, is unaffected by deletion of ybbB. Thus, ybbB is not required for the initial sulfurtransferase reaction but rather encodes a 2-selenouridine synthase that replaces a sulfur atom in 2-thiouridine in tRNA with selenium. Purified 2-selenouridine synthase containing a C-terminal His(6) tag exhibited spectral properties consistent with tRNA bound to the enzyme. In vitro mnm(5)se(2)U synthesis is shown to be dependent on 2-selenouridine synthase, SePO(3), and tRNA. Finally, we demonstrate that the conserved Cys(97) (but not Cys(96)) in the rhodanese sequence motif Cys(96)-Cys(97)-Xaa-Xaa-Gly is required for 2-selenouridine synthase in vivo activity. These data are consistent with the ybbB gene encoding a tRNA 2-selenouridine synthase and identifies a new role for the rhodanese homology domain in enzymes.