Neutrophils prevent rectal bleeding in ulcerative colitis by peptidyl-arginine deiminase-4-dependent immunothrombosis

OBJECTIVE

Bleeding ulcers and erosions are hallmarks of active ulcerative colitis (UC). However, the mechanisms controlling bleeding and mucosal haemostasis remain elusive.

DESIGN

We used high-resolution endoscopy and colon tissue samples of active UC (n = 36) as well as experimental models of physical and chemical mucosal damage in mice deficient for peptidyl-arginine deiminase-4 (PAD4), gnotobiotic mice and controls. We employed endoscopy, histochemistry, live-cell microscopy and flow cytometry to study eroded mucosal surfaces during mucosal haemostasis.

RESULTS

Erosions and ulcerations in UC were covered by fresh blood, haematin or fibrin visible by endoscopy. Fibrin layers rather than fresh blood or haematin on erosions were inversely correlated with rectal bleeding in UC. Fibrin layers contained ample amounts of neutrophils coaggregated with neutrophil extracellular traps (NETs) with detectable activity of PAD. Transcriptome analyses showed significantly elevated PAD4 expression in active UC. In experimentally inflicted wounds, we found that neutrophils underwent NET formation in a PAD4-dependent manner hours after formation of primary blood clots, and remodelled clots to immunothrombi containing citrullinated histones, even in the absence of microbiota. PAD4-deficient mice experienced an exacerbated course of dextrane sodium sulfate-induced colitis with markedly increased rectal bleeding (96 % vs 10 %) as compared with controls. PAD4-deficient mice failed to remodel blood clots on mucosal wounds eliciting impaired healing. Thus, NET-associated immunothrombi are protective in acute colitis, while insufficient immunothrombosis is associated with rectal bleeding.

CONCLUSION

Our findings uncover that neutrophils induce secondary immunothrombosis by PAD4-dependent mechanisms. Insufficient immunothrombosis may favour rectal bleeding in UC.

Paediatric antimicrobial stewardship programmes in the UK's regional children's hospitals

A survey was conducted in UK regional children's hospitals with paediatric intensive care and paediatric infectious disease (PID) departments to describe the characteristics of paediatric antimicrobial stewardship (PAS) programmes. A structured questionnaire was sent to PAS coordinators. 'Audit and feedback' was implemented in 13 out of 17 centres. Microbiology-led services were more likely to implement antimicrobial restriction (75% vs 33% in PID-led services), to focus on broad-spectrum antibiotics, and to review patients with positive blood cultures. PID-led services were more likely to identify patients from e-prescribing or drug charts and review all antimicrobials. A PAS network has been established.

Blood CD9+ B cell, a biomarker of bronchiolitis obliterans syndrome after lung transplantation

Bronchiolitis obliterans syndrome is the main limitation for long-term survival after lung transplantation. Some specific B cell populations are associated with long-term graft acceptance. We aimed to monitor the B cell profile during early development of bronchiolitis obliterans syndrome after lung transplantation. The B cell longitudinal profile was analyzed in peripheral blood mononuclear cells from patients with bronchiolitis obliterans syndrome and patients who remained stable over 3 years of follow-up. CD24^hi CD38^hi transitional B cells were increased in stable patients only, and reached a peak 24 months after transplantation, whereas they remained unchanged in patients who developed a bronchiolitis obliterans syndrome. These CD24^hi CD38^hi transitional B cells specifically secrete IL-10 and express CD9. Thus, patients with a total CD9⁺ B cell frequency below 6.6% displayed significantly higher incidence of bronchiolitis obliterans syndrome (AUC = 0.836, PPV = 0.75, NPV = 1). These data are the first to associate IL-10-secreting CD24^hi CD38^hi transitional B cells expressing CD9 with better allograft outcome in lung transplant recipients. CD9-expressing B cells appear as a contributor to a favorable environment essential for the maintenance of long-term stable graft function and as a new predictive biomarker of bronchiolitis obliterans syndrome-free survival.

Bacteremia in Childhood Life-Threatening Infections in Urban Gambia: EUCLIDS in West Africa

Background

The limited availability of microbiology services in sub-Saharan Africa impedes accurate diagnosis of bacterial pathogens and understanding of trends in prevalence and antibiotic sensitivities. We aimed to characterize bacteremia among hospitalized children in The Gambia and to identify factors associated with bacteremia and mortality.

Methods

We prospectively studied children presenting with suspected severe infection to 2 urban hospitals in The Gambia, between January 2013 and September 2015. Demographic and anthropometric data, clinical features, management, and blood culture results were documented. Urine screens for antibiotic activity were performed in a subset of participants.

Results

Of 411 children enrolled (median age, 29 months; interquartile range, 11–82), 79.5% (325 of 409) reported prehospital antibiotic use. Antimicrobial activity by urinary screen for antibiotic activity was detected in 70.8% (n = 80 of 113). Sixty-six bacterial pathogens were identified in 65 (15.8%) participants and Staphylococcus aureus predominated. Gram-positive organisms were more commonly identified than Gram-negative (P < .01). Antibiotic resistance against first-line antimicrobials (ampicillin and gentamicin) was common among Gram-negative bacteria (39%; range, 25%–100%). Factors significantly associated with bacteremia included the following: gender, hydration status, musculoskeletal examination findings, admission to the Medical Research Council The Gambia at London School of Hygiene & Tropical Medicine hospital, and meeting sepsis criteria. Those associated with increased mortality were presence of a comorbidity, clinical pallor, tachypnea, and altered consciousness. Tachycardia was associated with reduced mortality.

Conclusions

The bacteremia rate in children with suspected childhood life-threatening infectious diseases in The Gambia is high. The pattern of pathogen prevalence and antimicrobial resistance has changed over time compared with previous studies illustrating the importance of robust bacterial surveillance programs in resource-limited settings.

Ménage-à-Trois: The Ratio of Bicarbonate to CO2 and the pH Regulate the Capacity of Neutrophils to Form NETs

In this study, we identified and characterized the potential of a high ratio of bicarbonate to CO₂ and a moderately alkaline pH to render neutrophils prone to undergo neutrophil extracellular trap (NET) formation. Both experimental settings increased the rate of spontaneous NET release and potentiated the NET-inducing capacity of phorbol esters (phorbol-2-myristate-13-acetate), ionomycin, monosodium urate, and LPS. In contrast, an acidic environment impaired NET formation both spontaneous and induced. Our findings indicate that intracellular alkalinization of neutrophils in response to an alkaline environment leads to an increase of intracellular calcium and neutrophil activation. We further found that the anion channel blocker DIDS strongly reduced NET formation induced by bicarbonate. This finding suggests that the effects observed are due to a molecular program that renders neutrophils susceptible to NET formation. Inflammatory foci may be characterized by an acidic environment. Our data indicate that NET formation is favored by the higher pH at the border regions of inflamed areas. Moreover, our findings highlight the necessity for strict pH control during assays of NET formation.

Population pharmacokinetics and pharmacodynamics of teicoplanin in neonates: making better use of C-reactive protein to deliver individualized therapy

OBJECTIVES

There is uncertainty about the optimal teicoplanin regimens for neonates. The study aim was to determine the population pharmacokinetics (PK) of teicoplanin in neonates, evaluate currently recommended regimens and explore the exposure-effect relationships.

METHODS

An open-label PK study was conducted. Neonates from 26 to 44 weeks post-menstrual age were recruited (n = 18). The teicoplanin regimen was a 16 mg/kg loading dose, followed by 8 mg/kg once daily. Therapeutic drug monitoring and dose adjustment were not conducted. A standard two-compartment PK model was developed, followed by models that incorporated weight. A PK/pharmacodynamic (PD) model with C-reactive protein serial measurements as the PD input was fitted to the data. Monte Carlo simulations (n = 5000) were performed using Pmetrics. The AUCs at steady state and the proportion of patients achieving the recommended drug exposures (i.e. Cmin >15 mg/L) were determined. The study was registered in the European Clinical Trials Database Registry (EudraCT: 2012-005738-12).

RESULTS

The PK allometric model best accounted for the observed data. The PK parameters medians were: clearance = 0.435 × (weight/70)0.75 (L/h); volume = 0.765 (L); Kcp = 1.3 (h-1); and Kpc = 0.629 (h-1). The individual time-course of C-reactive protein was well described using the Bayesian posterior estimates for each patient. The simulated median AUC96-120 was 302.3 mg·h/L and the median Cmin at 120 h was 12.9 mg/L; 38.8% of patients attained a Cmin >15 mg/L by 120 h.

CONCLUSIONS

Teicoplanin population PK is highly variable in neonates, weight being the best descriptor of PK variability. A low percentage of neonates were able to achieve Cmin >15 mg/L. The routine use of therapeutic drug monitoring and improved knowledge on the PD of teicoplanin is required.

[Indications of lung transplantation: Patients selection, timing of listing, and choice of procedure]

Lung transplantation (LT) is now considered as an excellent treatment option for selected patients with end-stage pulmonary diseases, such as COPD, cystic fibrosis, idiopathic pulmonary fibrosis, and pulmonary arterial hypertension. The 2 goals of LT are to provide a survival benefit and to improve quality of life. The 3-step decision process leading to LT is discussed in this review. The first step is the selection of candidates, which requires a careful examination in order to check absolute and relative contraindications. The second step is the timing of listing for LT; it requires the knowledge of disease-specific prognostic factors available in international guidelines, and discussed in this paper. The third step is the choice of procedure: indications of heart-lung, single-lung, and bilateral-lung transplantation are described. In conclusion, this document provides guidelines to help pulmonologists in the referral and selection processes of candidates for transplantation in order to optimize the outcome of LT.

The United Kingdom Primary Immune Deficiency (UKPID) Registry: report of the first 4 years' activity 2008-2012

This report summarizes the establishment of the first national online registry of primary immune deficency in the United Kingdom, the United Kingdom Primary Immunodeficiency (UKPID Registry). This UKPID Registry is based on the European Society for Immune Deficiency (ESID) registry platform, hosted on servers at the Royal Free site of University College, London. It is accessible to users through the website of the United Kingdom Primary Immunodeficiency Network (www.ukpin.org.uk). Twenty-seven centres in the United Kingdom are actively contributing data, with an additional nine centres completing their ethical and governance approvals to participate. This indicates that 36 of 38 (95%) of recognized centres in the United Kingdom have engaged with this project. To date, 2229 patients have been enrolled, with a notable increasing rate of recruitment in the past 12 months. Data are presented on the range of diagnoses recorded, estimated minimum disease prevalence, geographical distribution of patients across the United Kingdom, age at presentation, diagnostic delay, treatment modalities used and evidence of their monitoring and effectiveness.

Emergency cardiac mechanical assistance: place of mucosal gastric tonometry as prognostic indicator

BACKGROUND AND OBJECTIVES

The death of patients treated by ventricular assist device is usually related to multiorgan failure for which a disorder of splanchnic circulation is blamed. Gastric tonometry (measurement of gastric intra-mucosal pressure of CO(2)) has already been studied in many fields and especially in cardiac surgery. The aim of this study was to investigate the prognostic value of gastric tonometry monitoring after implantation of a ventricular assist device.

METHODS

In this prospective study, all consecutive patients scheduled for a ventricular assist device were included. Gastric tonometry was added to standard monitoring. Data were collected (lactate, gastric CO(2) (PgCO(2)) during cardiopulmonary bypass, at admission to ICU, 24 and 48 h later and when norepinephrine was stopped. Preoperative biologic and haemodynamic data were also collected. The primary endpoint was death.

RESULTS

Fifty-six patients (50 men and 6 women) were included. In 91% of the cases, the mechanical assistance was biventricular. The objective of the assistance was a bridge to transplant in 93% (n = 27). Twenty-seven deaths (48%) occurred during the study, 59% (n = 16) of them took place before the cardiac transplantation (mean time = 18 +/- 16 days after assist device insertion). Many factors were found to be associated with death: weight (P = 0.018), red cells administration (P = 0.025), length of surgery (P = 0.016), PgCO(2) on admission to ICU (P = 0.040) and norepinephrine dose at 24 h.

CONCLUSIONS

Gastric tonometry has a prognostic value in the early postoperative hours after the implantation of a ventricular assist device.

Evaluation of the estimation of midazolam concentrations and pharmacokinetic parameters in intensive care patients using a bayesian pharmacokinetic software (PKS) according to sparse sampling approach

The aim of the study was to assess the performance of a bayesian program (PKS System, Abbott) for predicting midazolam concentrations and pharmacokinetic parameters in intensive care patients by comparing the pharmacokinetic parameters estimated by PKS to those calculated according to rich data. The study involved 42 patients receiving midazolam infusion for two hours or for several days. The program was used to predict plasma midazolam concentrations after feedback of 1, 2 or 3 concentrations. High correlation between observed and estimated concentrations was shown (r(2) > 0.992). Mean prediction error, mean absolute prediction error and root mean squared error were low for the patients of the reference and validation groups. From two or three feedback concentrations, midazolam pharmacokinetic parameters estimated by PKS were statistically comparable with those obtained using a rich pharmacokinetic analysis (P > 0.05 paired Wilcoxon test). Thus, PKS is useful for predicting midazolam concentrations and pharmacokinetic parameters when at least two feedback concentrations are known. This software seems to be appropriate for providing significant help to the clinician for midazolam dosage adjustment, according to midazolam concentrations and clinical sedation.

[Sedation induced by midazolam in intensive care: pharmacologic and pharmacokinetic aspects]

OBJECTIVE

Review on midazolam in order to optimize drug utilisation and therapeutic monitoring.

DATA SOURCES

Research of English or French articles published until August 2001, using Medline database. The key words were: midazolam, pharmacokinetics, pharmacodynamic, sedation, drug interaction.

STUDY SELECTION

Original articles, clinical cases and letters to the Editor were selected. Animal studies were excluded.

DATA EXTRACTION

The articles were analysed according to their interest in midazolam clinical practice.

DATA SYNTHESIS

Midazolam is a benzodiazepine widely used in intensive care unit, as a sedative, anxiety-relieving, and amnesic drug. Midazolam could be used in patients with cardiac, or respiratory failure, and in neurosurgery. A great interindividual variability on pharmacokinetic and pharmacodynamic response was observed. In intensive care patients, elimination half-life is known to be widely increased. Midazolam is metabolised by hepatic microsomes. The major metabolite is the 1-hydroxymidazolam, which is pharmacologically active. A prolonged sedation due to an accumulation of conjugated metabolite was observed in renal failure patients. Enzymatic inductors or inhibitors could influence pharmacokinetics and pharmacodynamic effects of midazolam.

CONCLUSION

According to midazolam pharmacokinetic and pharmacodynamic variability, an individual dosage adjustment is essential for long-term sedation. Target controlled sedation could be a mean to limit the variability and to reach quickly the pharmacodynamic effect.

Midazolam disposition in patients undergoing continuous venovenous hemodialysis

The aim of the study was to investigate the pharmacokinetics and removal of midazolam and unconjugated and glucuronidated 1-hydroxy-midazolam in 4 intensive care patients on continuous venovenous hemodialysis. Plasma midazolam and its metabolites were assessed by HPLC from blood samples collected during continuous infusion and after the end of infusion. Additional samples from the arterial and venous bloodlines and ultrafiltrate were drawn to calculate sieving coefficient and clearance of ultrafiltration. The elimination half-life of midazolam ranged from 7.6 to 22.8 hours. The clearance of ultrafiltration was between 0.13 and 4.7 ml/min and reached approximately 11% of the total clearance. The range of sieving coefficient was from 0.006 to 0.26, with an average fraction removal of 0.2%. 1-Hydroxy-midazolam glucuronide was removed by continuous hemodialysis (sieving 0.36 to 0.63), with a clearance of ultrafiltration ranging from 7.8 to 12.0 ml/min. These preliminary results showed that midazolam is not removed efficiently, and approximately half of the 1-hydroxy-midazolam glucuronide was removed by dialysis.

[Intensive care in lung and heart-lung transplantation]

Intensive care after lung, and heart-lung transplantation may have simple post operative course specially after preventive procedures of reperfusion injury, nosocomial infections during mechanical ventilation and immunosuppression risks. Nevertheless a severe mediastinal shift may occurred after single lung transplantation in emphysema. Rapid changes in ventilation/perfusion ratio during lung infection or rejection specially in pulmonary hypertension are responsible of dramatic respiratory failure. Knowledge of multiorgan dysfunction and multidisciplinary experience encourage to future development.

Disseminated Scedosporium prolificans (S. inflatum) infection after single-lung transplantation

This report concerns the first case of disseminated infection with Scedosporium prolificans (S. inflatum) that occurred in a patient who had received an organ transplant and was verified at autopsy. The patient underwent single (right)-lung transplantation and subsequently died on the 33rd postoperative day in a context of septic shock. S. prolificans was isolated from various specimens, including two cultured blood samples. The organism was associated with Candida albicans in some of these specimens. Autopsy revealed the presence of numerous nodular abscesses in the lungs, myocardium, kidneys, spleen, and gall bladder. These abscesses contained mycelial filaments and numerous oval conidia suggestive of Scedosporium species but no yeasts. MIC studies demonstrated the resistance of the S. prolificans isolate to amphotericin B, fluctyosine, miconazole, ketoconazole, and itraconazole, whereas the isolate of C. albicans was susceptible to amphotericin B, flucytosine, miconazole, and ketoconazole. From the data from our case and six published reports of cases of disseminated S. prolificans infection, it can be concluded that this filamentous fungus is a new agent responsible for the most serious mycoses in both neutropenic patients and patients who have undergone organ transplantation.

Enoximone and acute left ventricular failure during weaning from mechanical ventilation after cardiac surgery

OBJECTIVE

To evaluate enoximone, a phosphodiesterase III inhibitor, in the treatment of left ventricular failure during the weaning of patients from mechanical ventilation after heart surgery.

DESIGN

Open label, prospective, weaning trial.

SETTING

Cardiothoracic surgical intensive care unit (ICU) in a university hospital.

PATIENTS

Nine patients were studied after one or more unsuccessful attempts at weaning from mechanical ventilation due to left ventricular dysfunction.

INTERVENTION

For each patient, two respiratory weaning attempts were studied: the first one as a control and the second one with enoximone infused at a rate of 30 micrograms/kg/min for 30 mins, then at a rate of 10 micrograms/kg/min.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic measurements were performed at the following interval times: baseline during mechanical ventilation; during spontaneous ventilation with a T-piece for a minimum of 10 mins; during mechanical ventilation after the enoximone infusion for 30 mins; during spontaneous ventilation for a minimum of 10 mins with an enoximone infusion running. During spontaneous ventilation, enoximone increased cardiac index by 34% but mean artery, right atrial, and pulmonary artery occlusion pressures did not change. Despite an increase in venous admixture due to augmented cardiac index and inhibition of hypoxic vasoconstriction, no oxygen debt occurred because oxygen delivery increased. Seven of nine patients were weaned successfully from mechanical ventilation.

CONCLUSION

Because of its positive inotropic and vasodilatory properties, enoximone is helpful for respiratory weaning of patients with left ventricular failure after cardiac surgery.

[Current role of intra-aortic diastolic balloon counterpulsation in heart surgery]

Intra-aortic balloon counterpulsation (IABP) is a relatively non-invasive method of circulating assistance, easy to use and which has benefitted from a number of technological improvements in recent years. This retrospective study over 4 years was undertaken to analyse the results of IABP and to determine its role in therapeutic arsenal against cardiac failure. Sixty five patients, 57 coronary and 8 valvular cases, with an average age of 61 +/- 10 years were included. The indications of IABP were: a bridge to transplantation (3 cases), complications of coronary angioplasty (4 cases), and low cardiac output after cardiopulmonary bypass (58 cases), where IABP was curative in 85% of cases and prophylactic in 15% of cases (patients with risk factors of low output state after CPB). Beforehand, 65% of patients had poor left ventricular function (LVEF < 40% and/or CI < 2.2 l/mn/m2). An Aries Medical M700 console was used. The percutaneous femoral approach was feasible in 87% of cases. The results were: improvement with discharge from intensive care unit in 60% of cases, transient improvement in 7% of cases, no improvement in 15% of cases and cardiac transplantation in 8% of cases. The outcome was worse when the preoperative LV function was poor and when high dose inotropic agents had to be used. Survival was 100% in those patients in whom IABP was a prophylactic measure. The average duration of IABP was 72 hours, survival being significantly lower in those in whom IABP was continued for over 3 days. The complications (12.7%) were thromboembolic.(ABSTRACT TRUNCATED AT 250 WORDS)