A comprehensive review and comparison of L-tryptophan biosynthesis in Saccharomyces cerevisiae and Escherichia coli.

L-tryptophan and its derivatives are widely used in the chemical, pharmaceutical, food, and feed industries. Microbial fermentation is the most commonly used method to produce L-tryptophan, which calls for an effective cell factory. The mechanism of L-tryptophan biosynthesis in Escherichia coli, the widely used producer of L-tryptophan, is well understood. Saccharomyces cerevisiae also plays a significant role in the industrial production of biochemicals. Because of its robustness and safety, S. cerevisiae is favored for producing pharmaceuticals and food-grade biochemicals. However, the biosynthesis of L-tryptophan in S. cerevisiae has been rarely summarized. The synthetic pathways and engineering strategies of L-tryptophan in E. coli and S. cerevisiae have been reviewed and compared in this review. Furthermore, the information presented in this review pertains to the existing understanding of how L-tryptophan affects S. cerevisiae's stress fitness, which could aid in developing a novel plan to produce more resilient industrial yeast and E. coli cell factories.

NCR343 is required to maintain the viability of differentiated bacteroids in nodule cells in Medicago truncatula.

Bacteroid (name for rhizobia inside nodule cells) differentiation is a prerequisite for successful nitrogen-fixing symbiosis. In certain legumes, under the regulation of host proteins, for example, a large group of NCR (nodule cysteine rich) peptides, bacteroids undergo irreversible terminal differentiation. This process causes them to lose the ability to propagate inside nodule cells while boosting their competency for nitrogen fixation. How host cells maintain the viability of differentiated bacteroids while maximizing their nitrogen-reducing activities remains elusive. Here, through mutant screen, map-based cloning, and genetic complementation, we find that NCR343 is required for the viability of differentiated bacteroids. In Medicago truncatula debino1 mutant, differentiated bacteroids decay prematurely, and NCR343 is proved to be the casual gene for debino1. NCR343 is mainly expressed in the nodule fixation zone, where bacteroids are differentiated. In nodule cells, mature NCR343 peptide is secreted into the symbiosomes. RNA-Seq assay shows that many stress-responsive genes are significantly induced in debino1 bacteroids. Additionally, a group of stress response-related rhizobium proteins are identified as putative interacting partners of NCR343. In summary, our findings demonstrate that beyond promoting bacteroid differentiation, NCR peptides are also required in maintaining the viability of differentiated bacteroids.

Estimand in benefit-risk assessment.

ICH E9(R1) introduces the estimand framework to strengthen dialogues between sponsors and regulators during drug development. A well-structured benefit-risk assessment (BRA) framework also intends to facilitate communication among stakeholders. However, the estimand in ICH E9(R1) is written mainly from the perspective of a single measure of treatment effect in clinical trials. There is lack of systematic discussion on estimand in the context of BRA. This paper initiates the BRA discussion under the estimand framework. By identifying two types of BRA approaches, we summarize and discuss completed clinical trials, using the estimand language for BRA. Benefits and challenges of using estimand for BRA are also discussed.

Stigma receptors control intraspecies and interspecies barriers in Brassicaceae.

Flowering plants have evolved numerous intraspecific and interspecific prezygotic reproductive barriers to prevent production of unfavourable offspring1. Within a species, self-incompatibility (SI) is a widely utilized mechanism that rejects self-pollen2,3 to avoid inbreeding depression. Interspecific barriers restrain breeding between species and often follow the SI × self-compatible (SC) rule, that is, interspecific pollen is unilaterally incompatible (UI) on SI pistils but unilaterally compatible (UC) on SC pistils1,4-6. The molecular mechanisms underlying SI, UI, SC and UC and their interconnections in the Brassicaceae remain unclear. Here we demonstrate that the SI pollen determinant S-locus cysteine-rich protein/S-locus protein 11 (SCR/SP11)2,3 or a signal from UI pollen binds to the SI female determinant S-locus receptor kinase (SRK)2,3, recruits FERONIA (FER)7-9 and activates FER-mediated reactive oxygen species production in SI stigmas10,11 to reject incompatible pollen. For compatible responses, diverged pollen coat protein B-class12-14 from SC and UC pollen differentially trigger nitric oxide, nitrosate FER to suppress reactive oxygen species in SC stigmas to facilitate pollen growth in an intraspecies-preferential manner, maintaining species integrity. Our results show that SRK and FER integrate mechanisms underlying intraspecific and interspecific barriers and offer paths to achieve distant breeding in Brassicaceae crops.

Efficacy and Tolerability of Ezetimibe/Atorvastatin Fixed-dose Combination Versus Atorvastatin Monotherapy in Hypercholesterolemia: A Phase III, Randomized, Active-controlled Study in Chinese Patients.

PURPOSE: The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors ("statins") and the cholesterol-lowering medication ezetimibe are widely used in the treatment of patients with high- and very high-risk atherosclerotic cardiovascular disease. This study compared the efficacy and tolerability of a fixed-dose combination (FDC) of ezetimibe/atorvastatin (EZ/AS) with those of escalating doses of atorvastatin monotherapy in Chinese patients with hypercholesterolemia uncontrolled with statin monotherapy. METHODS: This Phase III, 12-week, randomized, double-blind study included patients aged 18 to 80 years with hypercholesterolemia uncontrolled on atorvastatin 10 or 20 mg/d monotherapy. After a 5-week run-in period of treatment with atorvastatin 10 or 20 mg/d (cohorts A and B, respectively), or a bioequivalent dosage of another statin, patients were randomized in a 1:1 ratio within each cohort to receive EZ/AS 10/10 mg FDC (EZ10/AS10) or atorvastatin 20 mg (AS20), once daily (cohort A); or EZ/AS 10/20 mg FDC (EZ10/AS20) or atorvastatin 40 mg (AS40), once daily (cohort B). The primary end point was the percentage change from baseline in low-density lipoprotein cholesterol (LDL-C). Tolerability was also evaluated. FINDINGS: Of the 454 patients enrolled, 412 (90.7%) completed the study. The percentage change from baseline in LDL-C was statistically greater with EZ10/AS10 treatment (n = 88) compared with AS20 monotherapy (n = 89) (treatment difference, -19.5%; 95% CI, -26.7% to -12.3%; P < 0.001). The percentage change from baseline in LDL-C was statistically greater with EZ10/AS20 treatment (n = 137) compared with AS40 monotherapy (n = 140) (treatment difference, -15.9%; 95% CI, -21.0% to -10.7%; P < 0.001). The safety profile was comparable between the EZ/AS and atorvastatin groups in the two cohorts. IMPLICATIONS: The LDL-C level at week 12 was significantly improved with both FDCs compared with escalated doses of atorvastatin (20 or 40 mg/d) in these Chinese patients with hypercholesterolemia uncontrolled on atorvastatin 10 or 20 mg/d. Both FDCs were well tolerated, with no new tolerability-related findings. Chinadrugtrials.org.cn identifier: CTR20190172; ClinicalTrials.gov identifier: NCT03768427.

Mechanics-driven nuclear localization of YAP can be reversed by N-cadherin ligation in mesenchymal stem cells.

Mesenchymal stem cells adopt differentiation pathways based upon cumulative effects of mechanosensing. A cell's mechanical microenvironment changes substantially over the course of development, beginning from the early stages in which cells are typically surrounded by other cells and continuing through later stages in which cells are typically surrounded by extracellular matrix. How cells erase the memory of some of these mechanical microenvironments while locking in memory of others is unknown. Here, we develop a material and culture system for modifying and measuring the degree to which cells retain cumulative effects of mechanosensing. Using this system, we discover that effects of the RGD adhesive motif of fibronectin (representative of extracellular matrix), known to impart what is often termed "mechanical memory" in mesenchymal stem cells via nuclear YAP localization, are erased by the HAVDI adhesive motif of the N-cadherin (representative of cell-cell contacts). These effects can be explained by a motor clutch model that relates cellular traction force, nuclear deformation, and resulting nuclear YAP re-localization. Results demonstrate that controlled storage and removal of proteins associated with mechanical memory in mesenchymal stem cells is possible through defined and programmable material systems.

Development of Dermestes tessellatocollis Motschulsky under different constant temperatures and its implication in forensic entomology.

Dermestidae generally appears on dry corpses and carcasses, especially if mummified or skeletonized. They are forensically important insect species for estimating longer postmortem intervals (PMI). As they develop, Dermestidae larvae undergo multiple larval ecdyses; however, a lack of guidelines for determining the larval instar limits their forensic application. Herein, we explored how temperature impacts the development of Dermestes tessellatocollis Motschulsky, 1860 (Coleoptera: Dermestidae). At seven constant temperatures (16, 19, 22, 25, 28, 31, and 34 °C), the developmental time from egg to adult was 163.87 ± 9.19, 103.56 ± 3.02, 63.59 ± 2.88, 51.49 ± 2.74, 47.86 ± 3.01, 44.62 ± 4.65, and 41.80 ± 4.87 days respectively. Four morphological indexes, including head capsule width, pronotum width, mesonotum width, and body length, were taken in vivo at regular intervals to identify methods for larval instar determination in D. tessellatocollis. The acquired morphological data were used to simulate fitted curves and equations depicting the relationship between the four morphological indexes and instars. From the validation experiment, we could hardly determine a specific instar based on the morphological indexes. The combination of morphometric data (head capsule, pronotum, and mesonotum width) generated the classification accuracy at 100%, 87.5%, 85%, and 93% for the 1st, 2nd/3rd, 4th/5th, and 6th/7th instars, respectively. Nevertheless, the accuracy was unsatisfactory for application in forensic casework. This study provides fundamental development data for adopting D. tessellatocollis in minimum postmortem interval (PMImin) estimations; however, further studies are needed to improve the classification accuracy for the larval instar determination.

Development of an Electronic Definition for De-escalation of Antibiotics in Hospitalized Patients.

BACKGROUND: Antimicrobial stewardship programs (ASPs) promote the principle of de-escalation: moving from broad- to narrow-spectrum agents and stopping antibiotics when no longer indicated. A standard, objective definition of de-escalation applied to electronic data could be useful for ASP assessments. METHODS: We derived an electronic definition of antibiotic de-escalation and performed a retrospective study among 5 hospitals. Antibiotics were ranked into 4 categories: narrow-spectrum, broad-spectrum, extended-spectrum, and agents targeted for protection. Eligible adult patients were cared for on inpatient units, had antibiotic therapy for at least 2 days, and were hospitalized for at least 3 days after starting antibiotics. Number of antibiotics and rank were assessed at 2 time points: day of antibiotic initiation and either day of discharge or day 5. De-escalation was defined as reduction in either the number of antibiotics or rank. Escalation was an increase in either number or rank. Unchanged was either no change or discordant directions of change. We summarized outcomes among hospitals, units, and diagnoses. RESULTS: Among 39 226 eligible admissions, de-escalation occurred in 14 138 (36%), escalation in 5129 (13%), and antibiotics were unchanged in 19 959 (51%). De-escalation varied among hospitals (median, 37%; range, 31-39%, P < .001). Diagnoses with lower de-escalation rates included intra-abdominal (23%) and skin and soft tissue (28%) infections. Critical care had higher rates of both de-escalation and escalation compared with wards. CONCLUSIONS: Our electronic de-escalation metric demonstrated variation among hospitals, units, and diagnoses. This metric may be useful for assessing stewardship opportunities and impact.

Independent Associations With 30- and 90-Day Unplanned Readmissions After Elective Lumbar Spine Surgery: A National Trend Analysis of 144 123 Patients.

BACKGROUND: Unplanned hospital readmissions contribute significantly to soaring national healthcare expenditures. To alleviate this burden, Centers for Medicare and Medicaid Services implemented initiatives to penalize hospitals for unplanned 30-d hospital readmissions. There is a paucity of data identifying patient risk factors independently associated with 30- and 90-d readmissions. OBJECTIVE: To investigate similarities in patient risk factors associated with 30- and 90-d unplanned readmissions following elective lumbar spine surgery. METHODS: The National Readmission Database (NRD) was queried to identify patients undergoing elective lumbar spine surgery between 2013 and 2014. Patients were grouped by no readmission (Non-R), unplanned readmission within 30 days (30-R), and unplanned readmission within 31 to 90 days (90-R). Multivariate analysis determined factors associated with 30- and 90-d readmissions. RESULTS: We identified 144 123 patients with 10 592 (7.3%) patients experiencing an unplanned readmission (30-R: n = 7228 [5.0%]; 90-R: n = 3364 [2.3%]; Non-R: n = 133 531). The most common inpatient complication observed in those patients readmitted was dural tear (30-R: 7.7%, 90-R: 4.6%, Non-R: 4.3%). The most prevalent 30- and 90-d complication seen among the readmitted cohort was infection (30-R: 18.5%, 90-R: 7.4%). In multivariate regression analysis, age, insurance status, chronic obstructive pulmonary disorder (COPD), depression, hypertension, diabetes, deficiency anemia, and obesity were independently associated with 30-d readmission; however, age and obesity were not independently associated with 90-d readmission. CONCLUSION: Our study demonstrated national unplanned readmission rates after elective spinal surgery to be 7.3%. With age, insurance status, COPD, depression, hypertension, diabetes, deficiency anemia, obesity, and depression all independently associated with unplanned hospital readmission. Future solutions that focus on reducing preventable readmissions may improve patient outcomes and reduce healthcare costs.

Prevalence and Cost Analysis of Chronic Pain After Hernia Repair: A Potential Alternative Approach With Neurostimulation.

OBJECTIVES: Chronic pain (CP) affects a significant number of patients following hernia repair, ranging from 11 to 54% in the literature. The aim of this study was to assess the prevalence, overall costs, and health care utilization associated with CP after hernia repair. MATERIALS AND METHODS: A retrospective longitudinal study was performed using the Truven MarketScan® data base to identify patients who develop chronic neuropathic posthernia repair pain from 2001 to 2012. Patients were grouped into CP and No Chronic Pain (No CP) cohorts. Patients were excluded if they 1) were under 18 years of age; 2) had a previous pain diagnosis; 3) had CP diagnosed <90 days after the index hernia repair; 4) had less than one year of follow-up; or 5) had less than one-year baseline record before hernia repair. Patients were grouped into the CP cohort if their CP diagnosis was made within the two years following index hernia repair. Total, outpatient, and pain prescription costs were collected in the period of five years prehernia to nine years posthernia repair. A longitudinal multivariate analysis was used to model the effects of chronic neuropathic posthernia repair pain on total inpatient/outpatient and pain prescription costs. RESULTS: We identified 76,173 patients who underwent hernia repair and met inclusion criteria (CP: n = 14,919, No CP: n = 61,254). There was a trend for increased total inpatient/outpatient and pain prescription costs one-year posthernia repair, when compared to baseline costs for both cohorts. In both cohorts, total inpatient/outpatient costs remained elevated from baseline through nine years posthernia repair, with the CP cohort experiencing significantly higher cumulative median costs (CP: $51,334, No CP: $37,388). The CP diagnosis year was associated with a 1.75-fold increase (p < 0.001) in total inpatient/outpatient costs and a 2.26-fold increase (p < 0.001) in pain prescription costs versus all other years. In the longitudinal analysis, the CP cohort had a 1.14-fold increase (p < 0.001) in total inpatient/outpatient costs and 2.00-fold increase (p < 0.001) in pain prescription costs. CONCLUSIONS: Our study demonstrates the prevalence of CP after hernia surgery to be nearly 20%, with significantly increased costs and healthcare resource utilization. While current treatment paradigms are effective for many, there remains a large number of patients that could benefit from an overall approach that includes nonopioid treatments, such as potentially incorporating neurostimulation, for CP that presents posthernia repair.

Denominator Matters in Estimating Antimicrobial Use: A Comparison of Days Present and Patient Days.

Patient days and days present were compared to directly measured person time to quantify how choice of different denominator metrics may affect antimicrobial use rates. Overall, days present were approximately one-third higher than patient days. This difference varied among hospitals and units and was influenced by short length of stay.Infect Control Hosp Epidemiol 2018;39:612-615.

Prevalence and Cost Analysis of Complex Regional Pain Syndrome (CRPS): A Role for Neuromodulation.

OBJECTIVE: The diagnosis and treatment of complex regional pain syndrome (CRPS) is challenging and there is a paucity of data describing its overall cost burden and quantifying its impact on the US healthcare system. The aim of this study was to assess the prevalence and healthcare utilization costs associated with CRPS. MATERIALS AND METHODS: A retrospective longitudinal study was performed using the Truven MarketScan® database to identify patients with a new indexed diagnosis of CRPS (Type I, II, or both) from 2001 to 2012. We collected total, outpatient, and pain prescription costs three years prior to CRPS diagnosis (baseline), at year of CRPS diagnosis, and eight-year post-CRPS diagnosis. A longitudinal multivariate analysis was used to model the estimated total and pain prescription cost ratios comparing patients diagnosed before and after CRPS. RESULTS: We included 35,316 patients with a newly indexed diagnosis of CRPS (Type I: n = 18,703, Type II: n = 14,599, Unspecified: n = 2014). Baseline characteristics were similar between the CRPS cohorts. Compared to two- and three-year baseline costs, one-year prior to diagnosis for all CRPS patients yielded the highest interquartile median [IQR] costs: total costs $7904[$3469, $16,084]; outpatient costs $6706[$3119, $12,715]; and pain prescription costs $1862[$147, $7649]. At the year of CRPS diagnosis, the median [IQR] costs were significantly higher than baseline costs: total costs $8508[$3943, $16,666]; outpatient costs $7251[$3527, $13,568]; and pain prescription costs $2077[$140, $8856]. Over the eight-year period after CRPS diagnosis, costs between all the years were similar, ranging from the highest (one-year) to lowest (seven-years), $4845 to $3888. The median total cumulative cost 8-years after CRPS diagnosis was $43,026 and $12,037 for pain prescription costs. [Correction added on 06 November 2017 after first online publication: the preceding sentence has been updated to demonstrate the median cumulative cost in replacement of the additive cumulative mean costs.]. During the CRPS diagnosis period, patients are expected to have a total cost 2.17-fold and prescription cost 2.56-fold of their baseline cost annually. CONCLUSIONS: Our study demonstrates that there is a significant increase in cost and healthcare resource utilization one-year prior to and around the time of CRPS diagnosis. Furthermore, there is an increased annual cost post-diagnosis compared to baseline costs prior to CRPS diagnosis.

Drivers and Risk Factors of Unplanned 30-Day Readmission Following Spinal Cord Stimulator Implantation.

OBJECTIVES: Unplanned 30-day readmission rates contribute significantly to growing national healthcare expenditures. Drivers of unplanned 30-day readmission after spinal cord stimulator (SCS) implantation are relatively unknown. The aim of this study was to determine drivers of 30-day unplanned readmission following SCS implantation. METHODS: The National Readmission Database was queried to identify all patients who underwent SCS implantation for the 2013 calendar year. Patients were grouped by readmission status, "No Readmission" and "Unplanned 30-day Readmission." Patient demographics and comorbidities were collected for each patient. The primary outcome of interest was the rate of unplanned 30-day readmissions and associated driving factors. A multivariate analysis was used to determine independent predictors of unplanned 30-day readmission after SCS implantation. RESULTS: We identified 1521 patients who underwent SCS implantation, with 113 (7.4%) experiencing an unplanned readmission within 30 days. Baseline patient demographics, comorbidities, and hospital characteristics were similar between both cohorts. The three main drivers for 30-day readmission after SCS implantation include: 1) infection (not related to SCS device), 2) infection due to device (limited to only hardware infection), and 3) mechanical complication of SCS device. Furthermore, obesity was found to be an independent predictor of 30-day readmission (OR: 1.86, p = 0.008). CONCLUSION: Our study suggests that infectious and mechanical complications are the primary drivers of unplanned 30-day readmission after SCS implantation, with obesity as an independent predictor of unplanned readmission. Given the technological advancements in SCS, repeated studies are necessary to identify factors associated with unplanned 30-day readmission rates after SCS implantation to improve patient outcomes and reduce associated costs.

Catheter ablation of atrial fibrillation in patients with heart failure and preserved ejection fraction.

BACKGROUND: Few studies have examined outcomes of catheter ablation for atrial fibrillation (AF) in patients with heart failure (HF) with preserved ejection fraction (HFpEF). OBJECTIVE: The purpose of this study was to compare outcomes of AF ablation in patients with HFpEF vs HF with reduced ejection fraction (HFrEF). METHODS: We performed a retrospective study of 230 patients with HF who underwent AF ablation, including 97 (42.2%) with HFrEF and 133 (57.8%) with HFpEF. Outcomes included adverse events, symptoms (Mayo AF Symptom Inventory [MAFSI]), New York Heart Association (NYHA) functional class, and freedom from recurrent atrial arrhythmia at 12 months. RESULTS: Overall, 150 of 230 patients had nonparoxysmal AF (62.8% HFpEF vs 63.0% HFrEF). Patients with HFpEF had a smaller mean left atrial diameter (4.4 ± 0.8 cm vs 4.7 ± 0.7 cm; P = .013) and were less likely to be taking a beta-blocker at baseline (72.9% vs 85.6%; P = .022). Median (Q1, Q3) procedure times (233 minutes [192, 290] vs 233.5 minutes [193.0, 297.5]; P = .780) and adverse events such as acute HF (3.8% vs 6.2%; P = .395) were similar between HFpEF and HFrEF patients. Freedom from recurrent atrial arrhythmia was not significantly different in HFpEF vs HFrEF patients (33.9% vs 32.6%; adjusted hazard ratio 1.47; 95% confidence interval 0.72-3.01), with similar improvements in NYHA functional class (-0.32 vs -0.19; P = .135) and MAFSI symptom severity (-0.23 vs -0.09; P = .116) after ablation. CONCLUSION: Catheter ablation of AF seems to have similar effectiveness in patients with HF, regardless of presence of systolic dysfunction. There were no significant differences in procedural characteristics, arrhythmia-free recurrence, or functional improvements between patients with HFpEF and those with HFrEF.