Factors contributing to sepsis-associated encephalopathy: a comprehensive systematic review and meta-analysis.

Background: This study aims to systematically assess the risk factors, the overall strength of association, and evidence quality related to sepsis-associated encephalopathy. Methods: A systematic search was conducted in the Cochrane Library, PubMed, Web of Science, and Embase for cohort or case-control studies published up to August 2023 on risk factors associated with sepsis-related encephalopathy. The selected studies were screened, data were extracted, and the quality was evaluated using the Newcastle-Ottawa Scale. Meta-analysis was performed using RevMan 5.3 software. The certainty of the evidence was assessed using the GRADE criteria. Results: A total of 13 studies involving 1,906 participants were included in the analysis. Among these studies, 12 were of high quality, and one was of moderate quality. Our meta-analysis identified six risk factors significantly associated with Serious Adverse Events (SAE). These included APACHE II, SOFA, age, tau protein, and IL-6, which were found to be risk factors with significant effects (standard mean difference SMD: 1.24-2.30), and albumin, which was a risk factor with moderate effects (SMD: -0.55). However, the certainty of evidence for the risk factors identified in this meta-analysis ranged from low to medium. Conclusion: This systematic review and meta-analysis identified several risk factors with moderate to significant effects. APACHE II, SOFA, age, tau protein, IL-6, and albumin were associated with sepsis-related encephalopathy and were supported by medium- to high-quality evidence. These findings provide healthcare professionals with an evidence-based foundation for managing and treating hospitalized adult patients with sepsis-related encephalopathy.

Analysis of fungal diversity in the gut feces of wild takin (Budorcas taxicolor).

Introduction: The composition of the intestinal microbiome correlates significantly with an animal's health status. Hence, this indicator is highly important and sensitive for protecting endangered animals. However, data regarding the fungal diversity of the wild Budorcas taxicolor (takin) gut remain scarce. Therefore, this study analyzes the fungal diversity, community structure, and pathogen composition in the feces of wild B. taxicolor. Methods: To ensure comprehensive data analyses, we collected 82 fecal samples from five geographical sites. Amplicon sequencing of the internal transcribed spacer (ITS) rRNA was used to assess fecal core microbiota and potential pathogens to determine whether the microflora composition is related to geographical location or diet. We further validated the ITS rRNA sequencing results via amplicon metagenomic sequencing and culturing of fecal fungi. Results and discussion: The fungal diversity in the feces of wild Budorcas taxicolor primarily comprised three phyla (99.69%): Ascomycota (82.19%), Fungi_unclassified (10.37%), and Basidiomycota (7.13%). At the genus level, the predominant fungi included Thelebolus (30.93%), Functional_unclassified (15.35%), and Ascomycota_unclassified (10.37%). Within these genera, certain strains exhibit pathogenic properties, such as Thelebolus, Cryptococcus, Trichosporon, Candida, Zopfiella, and Podospora. Collectively, this study offers valuable information for evaluating the health status of B. taxicolor and formulating protective strategies.

Online Causal Feature Selection for Streaming Features.

Recently, causal feature selection (CFS) has attracted considerable attention due to its outstanding interpretability and predictability performance. Such a method primarily includes the Markov blanket (MB) discovery and feature selection based on Granger causality. Representatively, the max-min MB (MMMB) can mine an optimal feature subset, i.e., MB; however, it is unsuitable for streaming features. Online streaming feature selection (OSFS) via online process streaming features can determine parents and children (PC), a subset of MB; however, it cannot mine the MB of the target attribute ( T ), i.e., a given feature, thus resulting in insufficient prediction accuracy. The Granger selection method (GSM) establishes a causal matrix of all features by performing excessively time; however, it cannot achieve a high prediction accuracy and only forecasts fixed multivariate time series data. To address these issues, we proposed an online CFS for streaming features (OCFSSFs) that mine MB containing PC and spouse and adopt the interleaving PC and spouse learning method. Furthermore, it distinguishes between PC and spouse in real time and can identify children with parents online when identifying spouses. We experimentally evaluated the proposed algorithm on synthetic datasets using precision, recall, and distance. In addition, the algorithm was tested on real-world and time series datasets using classification precision, the number of selected features, and running time. The results validated the effectiveness of the proposed algorithm.

Analysis of the microbial diversity in takin (Budorcas taxicolor) feces.

Introduction: The intestinal tract of animals is a complex and dynamic microecosystem that is inextricably linked to the health of the host organism. Takin (Budorcas taxicolor) is a threatened species, and its gut microbiome is poorly understood. Therefore, this study aimed to analyze the microbial community structure and potential pathogens of takin. Methods: Takin fecal samples were collected from five sites in a nature reserve to ensure the uniformity of sample collection, determine the effects of different geographical locations on gut microbes, and analyze the differences in microbial communities between sites. Subsequently, high-throughput 16S rDNA gene sequencing was performed to analyze the microbial diversity and potential pathogens in the gut; the findings were verified by isolating and culturing bacteria and metagenomic sequencing. Results and discussion: The takin gut microflora consisted mainly of four phyla: Firmicutes (69.72%), Bacteroidota (13.55%), Proteobacteria (9.02%), and Verrucomicrobiota (3.77%), representing 96.07% of all microorganisms. The main genera were UCG-005 (20.25%), UCG-010_unclassified (12.35%), Firmicus_unclassified (4.03%), and Rumino coccsea_unclassified (3.49%), while the main species were assigned to Bacteria_unclassified. Potential pathogens were also detected, which could be used as a reference for the protection of takin. Pseudomonas presented the highest abundance at Shuichiping and may represent the main pathogen responsible for the death of takin at the site. This study provides an important reference for investigating the composition of the bacterial community in the intestine of takin.

Performance of the renal resistive index and usual clinical indicators in predicting persistent AKI.

BACKGROUND: Early recognition of persistent acute kidney injury (AKI) could optimize management and prevent deterioration of kidney function. The Doppler-based renal resistive index (RI) has shown promising results for predicting persistent AKI in preliminary studies. Here, we aimed to evaluate the performance of renal RI, clinical indicators, and their combinations to predict short-term kidney prognosis in septic shock patients. METHOD: We performed a retrospective study based on data from a prospective study in a single-center general ICU between November 2017 and October 2018. Patients with septic shock were included. Clinical indicators were evaluated immediately at inclusion, and renal RI was measured within the first 12 h of ICU admission after hemodynamic stabilization. Persistent AKI was defined as AKI without recovery within 72 h. A multivariable logistic regression was used to select significant variables associated with persistent AKI. The discriminative power was evaluated by a receiver operating characteristic curve analysis. RESULT: Overall, 102 patients were included, 39 of whom had persistent AKI. Renal RI was higher in the persistent AKI patients than in those without persistent AKI: 0.70 ± 0.05 vs. 0.66 ± 0.05; p = 0.001. The performance of RI to predict persistent AKI was poor, with an area under the receiver operating characteristic curve (AUROC) of 0.699 [95% confidence interval (CI) 0.600-0.786]. A clinical prediction model combining serum creatinine at inclusion and the nonrenal SOFA score showed a better prediction ability for nonrecovery, with an AUROC of 0.877 (95% CI 0.797-0.933, p = 0.0012). The addition of renal RI to this model did not improve the predictive performance. CONCLUSION: The Doppler-based renal resistive index performed poorly in predicting persistent AKI and did not improve the clinical prediction provided by a combination of serum creatinine at inclusion and the nonrenal SOFA score in patients with septic shock.

The Influence of Environmental Variables on Home Range Size and Use in the Golden Snub-Nosed Monkey (Rhinopithecus roxellana) in Tangjiahe National Nature Reserve, China.

Accurate descriptions of home ranges can provide important information for understanding animal ecology and behavior and contribute to the formulation of conservation strategies. We used the grid cell method and kernel density estimation (KDE) to estimate the home range size of golden snub-nosed monkeys (Rhinopithecus roxellana) in Tangjiahe National Nature Reserve. We also used Moran's eigenvector maps analysis and variation partitioning to test the influence of environmental variables on home range use. The seasonal home range size was 15.4 km2 in spring, 11.6 km2 in summer, 13.7 km2 in autumn, and 15.6 km2 in winter, based on the grid cell method. The seasonal core area of 50% KDE was 9.86 km2 in spring, 5.58 km2 in summer, 7.20 km2 in autumn, and 4.23 km2 in winter. The environmental variables explained 63.60% of home range use intensity in spring, 72.21% in summer, 26.52% in autumn, and none in winter, and some environmental variables contributed to the spatial variation in home range use intensity. Water sources, tree density, and dominant trees of Chinese wingnut (Pterocarya stenoptera) were the important environmental factors determining home range use. These environmental factors require protection to ensure the survival of the golden snub-nosed monkey.

Application of the PDCA cycle for standardized nursing management in sepsis bundles.

BACKGROUND: To explore the application effect of plan, do, check and action circulation management mode in improving the compliance of sepsis bundle treatment. METHODS: 113 patients with sepsis admitted from January 1 to December 31, 2018 were selected as the control group, and the bundle treatment measures of sepsis were routinely implemented. The above treatment measures were completed within 6 h. 113 patients with sepsis admitted from January 1 to December 31, 2019 were selected as the study group. All clinical staff took the same measures as the control group, supplemented by PDCA cycle management. Objective to compare the changes of compliance of clinical staff to sepsis bundle treatment before and after the implementation of PDCA cycle management. RESULTS: Compared with the control group, the study group achieved the completion rate of sepsis bundle treatment in 1 h from 66.4 to 81.4%, the completion rate in 3 h from 77.0 to 89.4%, and the completion rate in 6 h from 82.3 to 95.6%. The difference was statistically significant (P < 0.05 for all). CONCLUSIONS: The implementation of PDCA cycle management mode can effectively improve the compliance of clinical staff to the bundle treatment of sepsis, improve the treatment efficiency of sepsis, and improve the quality of medical care.

Study on clinical nursing pathway to promote the effective implementation of sepsis bundle in septic shock.

BACKGROUND: There is still a certain gap between the effective implementation and requirements of sepsis bundle. Our aim is to establish the clinical nursing pathway of the cluster treatment of septic shock in the Intensive Care Unit and promote effective implementation of the cluster treatment of septic shock. METHODS: By means of evidence-based method, quality control index requirements and on-site investigation, the implementation process of clinical nursing pathway of the cluster treatment within 6 h of diagnosis of septic shock was established. RESULTS: After the implementation of clinical nursing pathway, the completion rate of septic shock cluster treatment was 81.4% (66.4%) in 1 h, 89.4% (77.0%) in 3 h, 95.5% (82.3%) in 6 h (P < 0.05), which was significantly improved in the experimental group compared with the control group. CONCLUSIONS: The clinical nursing pathway of septic shock cluster treatment is guided by evidence-based nursing, which emphasizes standardization and standardization of septic shock cluster treatment nursing under the guidance of the guideline, and can promote the effective implementation of septic shock cluster treatment, significantly improve efficiency of septic shock treatment and the quality of medical care.

A Solid-State Fluorescence Switch Based on Triphenylethene-Functionalized Dithienylethene With Aggregation-Induced Emission.

The development of novel dithienylethene-based fluorescence switches in the aggregated state, and the solid state is highly desirable for potential application in the fields of optoelectronics and photopharmacology. In this contribution, three novel triphenylethene-functionalized dithienylethenes (1-3) have been designed and prepared by appending triphenylethene moieties at one end of dithienylethene unit. Their chemical structures are confirmed by 1H NMR, 13C NMR, and HRMS (ESI). They display good photochromic behaviors with excellent fatigue resistance upon irradiation with UV or visible light in Tetrahydrofuran (THF) solution. Before irradiation with UV light, they exhibit Aggregation Induced Emission (AIE) properties and luminescence behaviors in the solid state. Moreover, upon alternating irradiation with UV/visible light, they display effective fluorescent switching behaviors in the aggregated state and the solid state. The experimental results have been validated by the Density Functional Theory (DFT) calculations. Thus, they can be utilized as novel fluorescence switches integrated in smart, solid-state optoelectronic materials and photopharmacology.

Different depths of sedation versus risk of delirium in adult mechanically ventilated patients: A systematic review and meta-analysis.

BACKGROUND: Delirium is multifactorial. This study aimed at determining the association between different depths of sedation and the risk of delirium in adult mechanically ventilated patients. METHODS: A systematic literature retrieval was conducted in databases including Cochrane Central Register of Controlled Trials, PubMed, Embase, Cumulative Index to Nursing and Allied Health Literature for publications available till December 2019 without limitation in study type, and followed by a secondary retrieval for related literature. STATA15.1 and WinBugs 14.3 were used in statistical analyses for different sedation depths as the intervention. The main endpoint was delirium occurrence. Secondary endpoints were agitation-related adverse events and mortality. RESULTS: We included 18 studies comprising 8001 mechanically ventilated patients. Different sedation depths were not associated with the occurrence of delirium (OR = 1.00, 95%CI: 0.64-1.58, P = 0.993). Among the 18 enrolled studies, this finding was not confounded by the dosage of benzodiazepines (OR = 0.96, 95%CI: 0.79-1.17, P = 0.717) in eight randomized controlled trials(RCTs) or the patients' disease severity(OR 0.95, 95%CI: 0.79-1.13, P = 0.548) in 10 RCTs. However, contrasting results were found in non-RCTs. The deeper sedation group had a significantly increased risk for death(OR = 1.82, 95% CI: 1.23-2.69, P = 0.003), whereas lighter sedation seemed a potential risk for agitation-related adverse events (OR = 0.61, 95%CI: 0.45-0.84, P = 0.002). CONCLUSIONS: It is inconclusive whether significantly different sedation depths would change the risk of delirium in adult mechanically ventilated patients. TRIAL REGISTRATION NUMBER: The study was registered in PROSPERO(http://www.crd.york.ac.uk/PROSPERO/) under registration number CRD42019145276.

Adjuvant Therapy: YiqiDitanTongfu Decoction With External Diaphragm Pacer for Chronic Obstructive Pulmonary Disease Patients With Difficulty Weaning From Mechanical Ventilation.

CONTEXT: Global morbidity from chronic obstructive pulmonary disease (COPD) is high worldwide. Diaphragm pacing (DP) can maintain the natural, negative pressure breathing of COPD patients with diaphragmatic muscle dysfunction. The YiqiDitanTongfu (YDTF) decoction has been used clinically with COPD patients to help them to wean from mechanical ventilation, with their ventilation functions being improved and the success rate of weaning being largely increased. OBJECTIVE: The study intended to investigate the combined therapeutic effects of external DP and the YDTF decoction for COPD patients who have had difficulty weaning from mechanical ventilation. DESIGN: This study was a retrospective cohort study. SETTING: The study occurred at the Hebei General Hospital and Hebei Province Chest Hospital (Hebei Province, Shijiazhuang, China). PARTICIPANTS: Participants were 90 patients with COPD + type 1 respiratory failure, 101 patients with COPD + Type 2 respiratory failure, and 96 patients with COPD at the compensated stage. INTERVENTION: The participants were randomly divided into 3 groups: (1) traditional treatment (control group), (2) traditional treatment plus treatment with a diaphragm pacemaker (DP group), and (3) traditional treatment plus treatment with a DP and a YDTF decoction (DP + YDTF group). All treatments occurred for 12 d. OUTCOME MEASURES: Relevant outcomes were measured and compared at baseline and postintervention, including the rapid shallow breathing index, tidal volume, maximum inspiratory pressure, degree of diaphragmatic muscle activity, maximum expiratory pressure, the successful rates of weaning from mechanical ventilation, the potential of hydrogen, the partial pressure of oxygen, partial pressure of carbon dioxide, and oxygen saturation. RESULTS: The patients treated with the DP plus the YDTF decoction were more successful in weaning from mechanical ventilation than those treated with DP. Of the patients with COPD + type 1 respiratory failure, 86.67% succeeded vs 70.00% of the DP patients. Of patients with COPD + type 2 respiratory failure, 87.88% succeeded vs 79.41% of the DP patients. CONCLUSION: The DP plus the YDTF concoction acted as a successful treatment for heart failure caused by CPOD in comparison with the DP or YDTF alone, providing evidence that the DP + YDTF concoction can serve as a competitive method for helping COPD patients to wean from mechanical ventilation.

Hemodynamic effects of inotropic drugs in heart failure: A network meta-analysis of clinical trials.

BACKGROUND: There is currently no consensus on the appropriate selection of inotropic therapy in ventricular dysfunction. The objective of the study was to detect the effects of different inotropes on the hemodynamics of patients who developed low cardiac output. METHODS: PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched (all updated December 31, 2017). The inclusion criteria were as follows: low cardiac index (CI < 2.5 L/min/m) or New York Heart Association class II-IV, and at least 1 group receiving an inotropic drug compared to another group receiving a different inotropic/placebo treatment. The exclusion criteria were studies published as an abstract only, crossover studies, and studies with a lack of data on the cardiac index. RESULTS: A total of 1402 patients from 37 trials were included in the study. Inotropic drugs were shown to increase the cardiac index (0.32, 95%CI:0.25, 0.38), heart rate (7.68, 95%CI:6.36, 9.01), and mean arterial pressure (3.17, 95%CI:1.96, 4.38) than the placebo. Overall, the pooled estimates showed no difference in terms of cardiac index, heart rate, mean arterial pressure, systemic vascular resistance, and mean pulmonary arterial pressure among the groups receiving different inotropes. CONCLUSIONS: Our systematic review found that inotrope therapy is not associated with the amelioration of hemodynamics. An accurate evaluation of the benefits and risks, and selection of the correct inotropic agent is required in all clinical settings.

Anti-atherosclerotic effect of hesperidin in LDLr-/- mice and its possible mechanism.

Hesperidin, a citrus bioflavonoid, exerts numerous pharmacological activities. However, its protective effect against atherosclerosis in vivo remains poorly understood. In the present study, we aimed to observe the effects of hesperidin on high fat diet (HFD)-induced atherosclerosis using LDL receptor deficient (LDLr-/-) mice. After 12 weeks of treatment, the animals were sacrificed. The blood samples were collected for further analysis. Mouse peritoneal macrophages were collected. Hepatic lipid content, quantification of atherosclerosis, assessment of oxidative stress and inflammation, gene expressions were performed on liver and aorta samples. The data showed that hesperidin ameliorated HFD-induced weight gain, improved insulin resistance and ameliorated hyperlipidemia. Hesperidin suppressed HFD-induced hepatic steatosis, atherosclerotic plaque area and macrophage foam cell formation. Further study showed that hesperidin down-regulated expressions of acetyl coenzyme A carboxylase alpha (ACCα) and fatty acid synthase (FAS) which are two key enzymes in fatty acid and triglyceride synthesis in liver; and upregulated expression of hepatic ATP-binding cassette transporters G8 (ABCG8), macrophage ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1) which are transporters involved in the process of reverse cholesterol transport. Hesperidin also reduced oxidative stress by normalizing activities of antioxidant enzymes and inflammation in HFD-fed LDLr-/- mice. These findings suggest that hesperidin reduced atherosclerosis via its pleiotropic effects, including improvement of insulin resistance, amelioration of lipid profiles, inhibition of macrophage foam cell formation, anti-oxidative effect and anti-inflammatory action.

Decreased cord blood estradiol levels in related to mothers with gestational diabetes.

Recent studies have revealed a link between estradiol (E2) and glucose homeostasis. We aimed to assess the association between cord blood hormone levels and the risk of gestational diabetes mellitus (GDM).A total of 204 pregnant women with GDM and 204 pregnant women without GDM (control) were included in the study. Maternal GDM were diagnosed using a 75 g oral glucose tolerance test at 24 to 26 weeks of gestation. Cord blood samples from neonates were collected immediately post delivery. Controls, which were randomly selected from the study population, were matched (cases to controls ratio: 1:1) to cases by age, sex of fetus, and gestational week.Pregravid body mass index (BMI) (mean ±â€Šstandard deviation) was (GDM vs. control): 24.5 ±â€Š2.1 versus 22.8 ±â€Š2.4 (P = .001). Cord blood estradiol in the GDM group was significantly lower than in the control group (P < .05). Pregravid BMI in the GDM group was significantly higher than in the control group (P < .05). Estradiol concentrations in cord blood were negatively correlated with birth weight (r = -0.121, P < .05). Conditional logistic regressions showed pregravid BMI, cord blood estradiol, and parity independently and positively predicted GDM. Multivariable regression splines characterize a nonlinear relationship between cord blood estradiol and GDM risk.These results demonstrate a relationship between cord blood estradiol levels and GDM. Estradiol might be involved in the pathophysiology of GDM. Further studies are needed to explore potential mechanism.

Differentially expressed genes in the testicular tissues of adenylyl cyclase 3 knockout mice.

Adenylate cyclase 3 (AC3) is an important component of the cyclic adenosine 3',5'-monophosphate (cAMP) signaling pathway and converts adenosine triphosphate into cAMP. Male mice with AC3 deletion (AC3-/-) are sterile. However, the mechanical mechanism remains unclear. By TUNEL staining, we found that cell apoptosis in the testicular tissues of AC3-/- mice increased significantly compared with that in the wild-type (AC3+/+) mice. Differentially expressed genes regulated by AC3 in the testicular tissues were identified by gene chip hybridization. We observed that the expression of 693 genes was altered in the testicular tissues of AC3-/- mice, including 330 up-regulated and 363 down-regulated gene expression with fold changes higher than 2 (≥2) as the standards. Furthermore, part of these differentially expressed genes was verified by the real-time fluorescence quantification PCR and immunofluorescent staining. The expression levels of the genes related to olfactory receptors, cell apoptosis, transcriptional activity, defensive reaction, cell adhesion, cell death, and immunoreactions were significantly altered in the testicular tissues of AC3-/- mice compared with AC3+/+ mice. In addition, the corresponding Ca2+, cAMP, and cell adhesion signaling pathways, as well as the signaling pathways related to axon guidance and cell interaction, were altered significantly in the AC3-/- mice. These data would help elucidate the general understanding of the mechanisms underlying the sterility in AC3-/- male mice.

A Provably Secure Aggregate Signature Scheme for Healthcare Wireless Sensor Networks.

Wireless sensor networks (WSNs) are being used in a wide range of applications for healthcare monitoring, like heart rate monitors and blood pressure monitors, which can minimize the need for healthcare professionals. In medical system, sensors on or in patients produce medical data which can be easily compromised by a vast of attacks. Although signature schemes can protect data authenticity and data integrity, when the number of users involved in the medical system becomes huge, the bandwidth and storage cost will rise sharply so that existing signature schemes are inapplicability for WSNs. In this paper, we propose an efficient aggregate signature scheme for healthcare WSNs according to an improved security model, which can combine multiple signatures into a single aggregate signature. The length of such an aggregate signature may be as long as that of an individual one, which can greatly decrease the bandwidth and storage cost for networks.

Thalidomide Promotes Morphine Efficacy and Prevents Morphine-Induced Tolerance in Rats with Diabetic Neuropathy.

Opioid analgesics have less efficacy in diabetic neuropathy treatment, and tolerance often occurs after chronic usage. Given that thalidomide can potentiate the morphine efficacy in diabetic neuropathy treatment, we investigated the effects of intrathecal administrations of thalidomide on morphine tolerance during the treatment of diabetic neuropathy. We found that intrathecal administrations of thalidomide (25 mg/kg/ml) potentiated the analgesic effects of morphine on mechanical hyperalgesia and prevented the development of morphine tolerance. While this treatment regimen did not alter the protein levels of µ-opioid receptor (MOR) in the spinal cord of diabetic rats, chronic morphine treatment robustly increased MOR binding density in the synaptic plasma membranes fraction, but decreased it in the microsomal fraction. Furthermore, thalidomide was able to reverse the distribution of MOR altered by chronic morphine treatment. Finally, STZ-induced diabetes promoted PKC activation and enhanced TNFα level in the spinal cord, which were attenuated by intrathecal administrations of thalidomide. Taken together, these results suggested that thalidomide may potentiate morphine efficacy on diabetic neuropathy and prevent the development of morphine tolerance by suppressing PKC activation and TNFα level in the spinal cord.

Structural insights into aldosterone synthase substrate specificity and targeted inhibition.

Aldosterone is a major mineralocorticoid hormone that plays a key role in the regulation of electrolyte balance and blood pressure. Excess aldosterone levels can arise from dysregulation of the renin-angiotensin-aldosterone system and are implicated in the pathogenesis of hypertension and heart failure. Aldosterone synthase (cytochrome P450 11B2, CYP11B2) is the sole enzyme responsible for the production of aldosterone in humans. Blocking of aldosterone synthesis by mediating aldosterone synthase activity is thus a recently emerging pharmacological therapy for hypertension, yet a lack of structural information has limited this approach. Here, we present the crystal structures of human aldosterone synthase in complex with a substrate deoxycorticosterone and an inhibitor fadrozole. The structures reveal a hydrophobic cavity with specific features associated with corticosteroid recognition. The substrate binding mode, along with biochemical data, explains the high 11ß-hydroxylase activity of aldosterone synthase toward both gluco- and mineralocorticoid formation. The low processivity of aldosterone synthase with a high extent of intermediates release might be one of the mechanisms of controlled aldosterone production from deoxycorticosterone. Although the active site pocket is lined by identical residues between CYP11B isoforms, most of the divergent residues that confer additional 18-oxidase activity of aldosterone synthase are located in the I-helix (vicinity of the O(2) activation path) and loops around the H-helix (affecting an egress channel closure required for retaining intermediates in the active site). This intrinsic flexibility is also reflected in isoform-selective inhibitor binding. Fadrozole binds to aldosterone synthase in the R-configuration, using part of the active site cavity pointing toward the egress channel. The structural organization of aldosterone synthase provides critical insights into the molecular mechanism of catalysis and enables rational design of more specific antihypertensive agents.

Structural basis of Rnd1 binding to plexin Rho GTPase binding domains (RBDs).

Plexin receptors regulate cell adhesion, migration, and guidance. The Rho GTPase binding domain (RBD) of plexin-A1 and -B1 can bind GTPases, including Rnd1. By contrast, plexin-C1 and -D1 reportedly bind Rnd2 but associate with Rnd1 only weakly. The structural basis of this differential Rnd1 GTPase binding to plexin RBDs remains unclear. Here, we solved the structure of the plexin-A2 RBD in complex with Rnd1 and the structures of the plexin-C1 and plexin-D1 RBDs alone, also compared with the previously determined plexin-B1 RBD.Rnd1 complex structure. The plexin-A2 RBD·Rnd1 complex is a heterodimer, whereas plexin-B1 and -A2 RBDs homodimerize at high concentration in solution, consistent with a proposed model for plexin activation. Plexin-C1 and -D1 RBDs are monomeric, consistent with major residue changes in the homodimerization loop. In plexin-A2 and -B1, the RBD ß3-ß4 loop adjusts its conformation to allow Rnd1 binding, whereas minimal structural changes occur in Rnd1. The plexin-C1 and -D1 RBDs lack several key non-polar residues at the corresponding GTPase binding surface and do not significantly interact with Rnd1. Isothermal titration calorimetry measurements on plexin-C1 and -D1 mutants reveal that the introduction of non-polar residues in this loop generates affinity for Rnd1. Structure and sequence comparisons suggest a similar mode of Rnd1 binding to the RBDs, whereas mutagenesis suggests that the interface with the highly homologous Rnd2 GTPase is different in detail. Our results confirm, from a structural perspective, that Rnd1 does not play a role in the activation of plexin-C1 and -D1. Plexin functions appear to be regulated by subfamily-specific mechanisms, some of which involve different Rho family GTPases.