Impact of azole drugs on energetics,kinetics, and ligand migration pathways of CO photo-dissociation in bacterial flavohemoglobins

Flavohemoglobins (fHbs) are heme proteins found in prokaryotic and eukaryotic microbes. They are involved in NO detoxification through an NO˙ dioxygenase mechanism. The N-terminal heme globin domain allows for binding of gaseous ligands whereas a C-terminal NADH/FADH binding domain facilitates association of redox cofactors necessary for ligand reduction. The NO˙ dioxygenase function is important in facilitating immune resistance by protecting the cell from nitrosative stress brought about by a host organism; as a result, bacterial flavoHbs have recently been considered as targets for the development of new antibiotics. Here, photoacoustic calorimetry and transient absorption spectroscopy have been used to characterize energetics, structural dynamics, and kinetics of CO migration within bacterial flavoHbs from Ralstonia eutropha (FHP) and Staphylococcus aureus (HMP_Sa) in the presence and absence of antibiotic azole compounds. In FHP, the ligand photo-release is associated with ΔH = 26.2 ± 7.0 kcal mol⁻¹ and ΔV = 25.0 ± 1.5 mL mol⁻¹ while in HMP_Sa, ΔH = 34.7 ± 8.0 kcal mol⁻¹ and ΔV = 28.6 ± 17 mL mol⁻¹ were observed, suggesting distinct structural changes associated with ligand escape from FHP and HMP_Sa. In the presence of ketoconazole, the CO escape leads to a more negative enthalpy change and volume change whereas association of miconazole to FHP or HMP_Sa does not impact the reaction volume. These data are in agreement with the computational results that propose distinct binding sites for ketoconazole and miconazole on CO bound FHP. Miconazole or ketoconazole binding to either protein has only a negligible impact on the CO association rates, indicating that azole drugs do not impact flavoHbs interactions with gaseous ligands but may inhibit the NOD activity through preventing the electron transfer between FAD and heme cofactors.

Impact of ketoconalzole and miconazole on structural dynamics of flavohemoglobin.     

Retraction: Synthesis and characterization of Co/Ti layered double hydroxide and its application as a photocatalyst for degradation of aqueous Congo Red

Retraction of ‘Synthesis and characterization of Co/Ti layered double hydroxide and its application as a photocatalyst for degradation of aqueous Congo Red’ by Priyadarshi Roy Chowdhury and Krishna G. Bhattacharyya, RSC Adv., 2015, 5, 92189–92206.

The Royal Society of Chemistry hereby wholly retracts this RSC Advances article due to concerns with the reliability of the data in the published article.The XPS data in Fig. 4B, E and F have been duplicated in another publication, but reported as a different material.¹A repeating segment can be observed in the TEM image presented in Fig. 10C, which indicates that this image has been manipulated.There are unexpected similarities in the baseline of the EDX spectrum in Fig. 10F and the EDX spectra in other publications, which have all been reported as different materials.^1–3There are repeating motifs within the AFM image in Fig. 10G, which indicates that this image has been manipulated. Many of these motifs can also be observed in an AFM image in another publication, but representing a different material.²The image in Fig. 10I is unreliable as it has subsequently been reused in unpublished material to represent different materials.The FTIR data presented in Fig. 16B (blue, red and green spectra) illustrate duplication of data, given that these experiments were reported under different reaction conditions.Given the number and significance of the concerns about the validity of the data, the findings presented in this paper are no longer reliable.Priyadarshi Roy Chowdhury and Krishna G. Bhattacharyya were informed about the retraction of the article but did not respond.Signed: Laura Fisher, Executive Editor, RSC AdvancesDate: 12^th March 2020     

Adipose-derived stem cells and rabbit bone regeneration: histomorphometric, immunohistochemical and mechanical characterization

Background

In the last few years, several attempts have been made to treat large bone loss, including the use of tissue engineering with osteoinductive scaffolds and cells. This study highlights the role of mesenchymal stem cells from adipose tissue (ASCs; adipose-derived stem cells) in a rabbit bone regeneration model.

Methods

We compared the neoformed bone tissues achieved by treating critical tibial defects with either hydroxyapatite alone (HA, group I) or hydroxyapatite–autologous ASC constructs (ASCs-HA, group II), investigating their histomorphometric, immunohistochemical and biomechanical properties.

Results

After eight weeks of follow-up, we observed advanced maturation and a spatial distribution of new bone that was more homogeneous in the inner parts of the pores in group II, not just along the walls (as seen in group I). The new tissue expressed osteogenic markers, and biomechanical tests suggested that the newly formed bone in group II had a higher mineral content than that in group I. Although variability in differentiation was observed among the different cell populations in vitro, no differences in bone healing were observed in vivo; the variability seen in vitro was probably due to local microenvironment effects.

Conclusions

Tibial defects treated with rabbit ASCs-HA showed an improved healing process when compared to the process that occurred when only the scaffold was used. We suggest that implanted ASCs ameliorate the bone reparative process either directly or by recruiting resident progenitor cells.     

Virtual drug design： Skpl-Skp2 inhibition targets cancer stem cells

The dysregulation of pathways regulat-ing cellular function is a frequent hall-mark of cancer and the development of specific pathway inhibitors that alter tumor growth and progression are the focus of multiple recent studies. E3 ubiquitin ligases are a large group of diverse protein enzymes that specifically target proteins for dear- ance, and their importance to normal cel-lular function is illustrated in the many diseases associated with their loss of func- tion or inappropriate targeting. S-phase kinase-associated protein 2 （Skp2） is an F box protein that plays critical roles in cell-cycle progression, senescence, metabolism, and acts as an Skpl-Cullin-l-F box （SCF） ubiquitin ligase substrate recognition fac-tor. Overexpression of Skp2 is associated with poor prognosis and metastasis in many cancers and is a well validated drug target. In a recent report, Chart et al. have iden-tified an Skp2 inhibitor that selectively impairs Skp2 E3 ligase activity using an integrated virtual high-throughput drug screening and experimental validation approach. This Skp2 inhibitor restricts cancer stemness and potentiates sensitivity to chemotherapeutic agents in multiple ani-mal tumor models. These findings identify a new novel small molecule that targets the Skp2 and reduces tumor growth by attenu-ating aerobic glycolysis and inducing cel-lular senescence.     

The difficult airway with recommendations for management – Part 1 – Difficult tracheal intubation encountered in an unconscious/induced patient

Background

Previously active in the mid-1990s, the Canadian Airway Focus Group (CAFG) studied the unanticipated difficult airway and made recommendations on management in a 1998 publication. The CAFG has since reconvened to examine more recent scientific literature on airway management. The Focus Group’s mandate for this article was to arrive at updated practice recommendations for management of the unconscious/induced patient in whom difficult or failed tracheal intubation is encountered.

Methods

Nineteen clinicians with backgrounds in anesthesia, emergency medicine, and intensive care joined this iteration of the CAFG. Each member was assigned topics and conducted reviews of Medline, EMBASE, and Cochrane databases. Results were presented and discussed during multiple teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made together with assigned levels of evidence modelled after previously published criteria.

Conclusions

The clinician must be aware of the potential for harm to the patient that can occur with multiple attempts at tracheal intubation. This likelihood can be minimized by moving early from an unsuccessful primary intubation technique to an alternative “Plan B” technique if oxygenation by face mask or ventilation using a supraglottic device is non-problematic. Irrespective of the technique(s) used, failure to achieve successful tracheal intubation in a maximum of three attempts defines failed tracheal intubation and signals the need to engage an exit strategy. Failure to oxygenate by face mask or supraglottic device ventilation occurring in conjunction with failed tracheal intubation defines a failed oxygenation, “cannot intubate, cannot oxygenate” situation. Cricothyrotomy must then be undertaken without delay, although if not already tried, an expedited and concurrent attempt can be made to place a supraglottic device.     

Thinking About Trauma: The Unique Contributions of Event Centrality and Posttraumatic Cognitions in Predicting PTSD and Posttraumatic Growth

Researchers have been investigating possible pathways to negative (posttraumatic stress disorder [PTSD]) and positive (posttraumatic growth [PTG]) reactions to trauma in recent decades. Two cognitive constructs, event centrality and posttraumatic cognitions, have been implicated to uniquely predict PTSD symptoms in an undergraduate sample. The current pair of studies attempted to (a) replicate this finding in an undergraduate sample, (b) replicate this finding in a treatment‐seeking sample, and (c) explore whether these 2 cognitive constructs uniquely predict PTG. The first study consisted of 500 undergraduate students, whereas the second study consisted of 53 treatment‐seeking clients. Results indicated both posttraumatic cognitions and event centrality uniquely predicted PTSD in the undergraduate (R² = .46) and treatment‐seeking samples (R² = .46). These 2 cognitive constructs also predicted PTG in the undergraduate sample (R² = .37), but only posttraumatic cognitions predicted PTG in the treatment‐seeking sample (R² = .17). The relationships between PTG varied, depending on whether PTG for high or low event‐centrality events were assessed. The original model was supported within both populations for PTSD symptoms, and its extension to PTG was supported within the treatment‐seeking sample. These results underscore cognitive and narrative factors in the progression of trauma.     

Associations between fibroblast growth factor 23 and cardiac characteristics in pediatric heart failure

Background

In adults with heart failure, elevated levels of fibroblast growth factor 23 (FGF23) are associated with mortality. Data on FGF23 levels in pediatric heart failure are lacking.

Patients and methods

We conducted a cross-sectional study of 17 healthy children (mean age 13 years) and 20 pediatric patients with heart failure (mean age 12 years) who underwent echocardiography and for whom the following measurements were taken: plasma FGF23 and parathyroid hormone (PTH) and serum phosphate, creatinine and N-terminal prohormone brain natriuretic peptide (NT-proBNP). Symptom severity was assessed with the New York Heart Association and the Ross classification systems.

Results

Of the 20 patients, 11 had dilated cardiomyopathy, four had congenital heart disease, three had hypertrophic cardiomyopathy, one had a failing heart transplant and one had pulmonary hypertension. Mean phosphate levels in these patients were within the reported reference range for healthy children. Median PTH levels were in the normal range in patients and controls. The median FGF23 level was higher in patients versus controls (110.9 vs. 66.4 RU/ml; P?=?0.03) and higher in patients on diuretics versus other patients (222.4 vs. 82.1 RU/ml; P?=?0.01). Levels of FGF23 and NT-proBNP were directly correlated (r?=?0.47, P?=?0.04), and patients with greater physical functional impairment had higher FGF23 levels (142.5 in those with moderate-severe limitation vs. 92.8 RU/ml in those with no limitation; P?=?0.05). Among patients with dilated cardiomyopathy, higher FGF23 levels were associated with a greater left ventricular end-diastolic diameter (r?=?0.63, P?=?0.04).

Conclusion

FGF23 levels are elevated in children with heart failure and are associated with diuretic use, severity of heart failure and left ventricular dilation.     

Survival after burn in a sub-Saharan burn unit: Challenges and opportunities

Background

Burns are among the most devastating of all injuries and a major global public health crisis, particularly in sub-Saharan Africa. In developed countries, aggressive management of burns continues to lower overall mortality and increase lethal total body surface area (TBSA) at which 50% of patients die (LA50). However, lack of resources and inadequate infrastructure significantly impede such improvements in developing countries.

Methods

This study is a retrospective analysis of patients admitted to the burn center at Kamuzu Central Hospital in Lilongwe, Malawi between June 2011 and December 2012. We collected information including patient age, gender, date of admission, mechanism of injury, time to presentation to hospital, total body surface area (TBSA) burn, comorbidities, date and type of operative procedures, date of discharge, length of hospital stay, and survival. We then performed bivariate analysis and logistic regression to identify characteristics associated with increased mortality.

Results

A total of 454 patients were admitted during the study period with a median age of 4 years (range 0.5 months to 79 years). Of these patients, 53% were male. The overall mean TBSA was 18.5%, and average TBSA increased with age—17% for 0–18 year olds, 24% for 19–60 year olds, and 41% for patients over 60 years old. Scald and flame burns were the commonest mechanisms, 52% and 41% respectively, and flame burns were associated with higher mortality. Overall survival in this population was 82%; however survival reduced with increasing age categories (84% in patients 0–18 years old, 79% in patients 19–60 years old, and 36% in patients older than 60 years). TBSA remained the strongest predictor of mortality after adjusting for age and mechanism of burn. The LA50 for this population was 39% TBSA.

Discussion

Our data reiterate that burn in Malawi is largely a pediatric disease and that the high burn mortality and relatively low LA50 have modestly improved over the past two decades. The lack of financial resources, health care personnel, and necessary infrastructure will continue to pose a significant challenge in this developing nation. Efforts to increase burn education and prevention in addition to improvement of burn care delivery are imperative.     

Utility of Choline Positron Emission Tomography/Computed Tomography for Lymph Node Involvement Identification in Intermediate- to High-risk Prostate Cancer: A Systematic Literature Review and Meta-analysis

Context

Determination of tumour involvement of regional lymph nodes in patients with prostate cancer (PCa) is of key importance for the proper planning of treatment.

Objectives

To provide a critical overview of published reports and to perform a meta-analysis about the diagnostic performance of 18F-choline and 11C-choline positron emission tomography (PET) or PET/computed tomography (CT) in the lymph node staging of PCa.

Evidence acquisition

A Medline, Web of Knowledge, and Google Scholar search was carried out to select English-language articles published before January 2012 that discussed the diagnostic performance of choline PET to individualise lymph node disease at initial staging in PCa patients. Articles were included only if absolute numbers of true-positive, true-negative, false-positive, and false-negative test results were available or derivable from the text and focused on lymph node metastases. Reviews, clinical reports, and editorial articles were excluded. All complete studies were reviewed; thus qualitative and quantitative analyses were performed.

Evidence synthesis

From the year 2000 to January 2012, we found 18 complete articles that critically evaluated the role of choline PET and PCa at initial staging. The meta-analysis was carried out and consisted of 10 selected studies with a total of 441 patients. The meta-analysis provided the following results: pooled sensitivity 49.2% (95% confidence interval [CI], 39.9–58.4) and pooled specificity 95% (95% CI, 92–97.1). The area under the curve was 0.9446 (p < 0.05). The heterogeneity ranged between 22.7% and 78.4%. The diagnostic odds ratio was 18.999 (95% CI, 7.109–50.773).

Conclusions

Choline PET and PET/CT provide low sensitivity in the detection of lymph node metastases prior to surgery in PCa patients. A high specificity has been reported from the overall studies. Studies carried out on a larger scale with a homogeneous patient population together with the evaluation of cost effectiveness are warranted.