Enhancement ofAcinetobacterbaumanniibiofilm growth by cephem antibiotics via enrichment of protein and extracellular DNAin thebiofilm matrices

AIMS

To determine the effects of subinhibitory concentrations of eight cephem and carbapenem antibiotics on thebiofilm formation ofAcinetobacterbaumanniicells and examine itseffect on pre-established biofilms.

METHODS AND RESULTS

Effects of antibiotics on biofilm formation were assayed using microtiter plates with polystyrene peg-lids.Cefmetazole, ceftriaxone, ceftazidime, and cefpirome increased the biomass of pre-established biofilms on pegs in the range of their sub-minimum inhibitory concentrations, whereas none increased biofilm formation by planktonic cells. Carbapenems had a negative effect.The constituents of antibiotic-induced biofilms were analyzed. Ceftriaxoneor ceftazidimetreatment markedly increased the matrix constituent amounts in the biofilms (carbohydrate, 2.7-fold; protein, 8.9-12.7-fold; lipid, 3.3-3.6-fold; DNA, 9.1-12.2-fold; outer membrane vesicles, 2.7-3.8-fold; and viable cells,6.8-10.1-fold).The antibiotic-enhanced biofilmshad increased outer membrane protein A and were resistant to the anti-biofilm effect of azithromycin.

CONCLUSIONS

Some cephems increased the biomass of pre-established biofilms in the ranges of their sub-minimum inhibitory concentrations.The antibiotic-enhanced biofilmspossessed more virulent characteristics than normal biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

Incomplete administration of certain cephems followingbiofilm-related Ac.baumannii infectionscould adversely cause exacerbated and chronic clinical results.

Prognostic impact of atrial fibrillation under oral anticoagulation therapy in patients with type B acute aortic dissection

Background

Patients with acute aortic dissection (AAD) sometimes are complicated with atrial fibrillation (AF). However, the impact of AF and the use of oral anticoagulation (OAC) on the prognosis of AAD remains unclear. In this study, we evaluated the prognostic impact of AF and OAC therapy in patients with type B AAD.

Methods

Consecutive patients diagnosed with type B AAD between January 2010 and December 2020 in our university hospital were retrospectively analyzed. All patients were divided into 2 groups based on the concomitance with or without AF. The primary endpoint was set as major adverse cardiovascular events (MACEs), including all-cause death, enlargement of aortic diameter, aortic ruptures, and cerebral infarction. Kaplan-Meier survival curves were constructed, and Cox proportional hazards analysis was performed to identify independent predictors of clinical events at 1 year.

Results

A total of 146 patients diagnosed with type B AAD were enrolled, with a mean age of 66±12 years, and 81% of male. Thirty-two patients (22%) experienced MACEs during 272±142 days-observation. Concomitant AF was observed in 27 patients (18%). In the Kaplan-Meier curve analysis, the patients with AF showed significantly higher events than those without AF (log-lank p<0.001). In the multivariate Cox proportional hazards models, presence of AF (HR: 2.402, 95% CI: 1.099–4.978 p=0.029), maximum descending aorta diameter (HR: 1.0366, 95% CI: 1.005–1.064 p=0.023), and age>75 years (HR: 2.635, 95% CI: 1.268–5.388 p=0.011) were independent predictors of MACEs. Regarding OAC in patients with AF, Kaplan-Meier analysis showed that usage of OAC was associated with a higher incidence of MACEs than those without (log-rank, p=0.036)

Conclusion

Presence of AF, enlargement of descending aorta diameter, and age were independent predictors of future MACEs in patients with type B AAD. Additionally, usage of OAC is associated with MACEs in patients with type B AAD complicated with AF.

Funding Acknowledgement

Type of funding sources: None.

Catheter contact angle influences local impedance drop during radiofrequency catheter ablation: insight from a porcine experimental study

Background

Local impedance (LI) at a distal tip of the ablation catheter can indirectly measure catheter contact and tissue temperature during radiofrequency catheter ablation (RFCA). LI decreases by RFCA, and a degree of LI drop is correlated with lesion size. However, data on the effects of catheter contact angle on lesion size and LI drop were scarce. This study aimed to evaluate the influence of catheter contact angle on lesion size and LI drop in a porcine experimental study.

Methods

Lesions were created on porcine myocardial left ventricles by the LI-sensing ablation catheter (IntellaNav MiFi OI®). Contact force (CF) was measured using pressure to current transducer (load cell). Radiofrequency ablation was performed with a power of 30 Watt and a duration of 30 seconds. CF (0g, 5g, 10g, 20g, and 30g) and catheter angle (30°, 45°, and 90°) were changed in each set (total 120 lesions, n=8 each). LI rise, LI drop by RF application, and lesion size (maximum lesion width, maximum surface width, and maximum lesion depth) were evaluated.

Results

There was no angular dependence in LI rise in all CF. The values of LI rise increased as CF increased. The LI drop also increased as CF increased in all contact angles. Regarding the difference of catheter angles, LI drop with 90° was lower than those with 30° and 45°in CF 10g, 20g, and 30g, respectively. Maximum lesion width and surface width were larger in 30° and 45° than those in 90°, whereas there were no differences in maximum lesion depth.

Conclusion

LI drop in 90° were significantly lower than those in 45° and 30°. Although lesion depths were not different among the three angles, the absolute values of LI drop were different. Caution should be exercised to comprehend the LI drop with catheter angles.

Funding Acknowledgement

Type of funding sources: None.

Lesional activation of Tc 17 cells in Behçet's disease and psoriasis supports HLA-class I-mediated autoimmune responses

BACKGROUND

Behçet's disease (BD) presents with lymphocytic and neutrophilic vasculitis of unknown aetiology. HLA-B*51 ERAP1 and IL12R/IL23R are genetic risk factors. IL-23 regulates IL-17A, which controls recruitment and activation of neutrophils.

OBJECTIVES

To determine pathological changes in BD skin lesions related to the complex genetic predisposition METHODS: We characterised the expression of IL-17A and IL-23A in various cell types by immunohistological double staining of sections from papulopustular skin lesions (PPL) of acute attacks of BD and lesions of psoriasis vulgaris (PV), another HLA-class I-associated T-cell mediated autoimmune disease in which excessive T-cell derived IL-17A production promotes neutrophil activation.

RESULTS

We found that in BD lesions, as in psoriasis, actively expanding CD8⁺ T cells were the predominant source of IL-17A. IL-17A⁺ CD8⁺ T (Tc17) cells outnumbered infiltrating IL-17A⁺ CD4⁺ T cells. Unlike the epidermal localisation of CD8⁺ T cells in psoriasis, Tc17 cells in BD lesions infiltrated mainly the perivascular tissue and also the blood vessel walls of dermis and subcutaneous tissue. They colocalised with a marked IL-23A expression by CD11c⁺ dendritic cells (DCs) and CD68⁺ macrophages. IL-17A expression was associated with extensive recruitment of neutrophils around blood vessels that formed neutrophil extracellular traps (NETs).

CONCLUSIONS

In BD, the genetic predisposition may mediate antigen-specific activation and differentiation of a T_c 17 response, possibly targeting endothelial antigens. Neutrophils recruited by IL-17A in this process may enhance tissue damage by extensive NET formation (NETosis). Thus, the IL-23/IL-17 axis presumably controls neutrophilic inflammation in BD vasculitis in the context of a predominant antigen-specific CD8⁺ T-cell response.

Novel risk factor for fatal arrhythmia in Brugada syndrome

Background

Brugada syndrome (BrS) is a genetic disease associated with increased risk of ventricular fibrillation (VF)/ventricular tachycardia (VT). The VF/VT in BrS occurs more frequently during a night time or at a rest with parasympathetic nerve activation. Some risk factors of VF/VT occurrence in BrS have been elucidated, however, it remains controversial about risk stratification. Salusin-β is an endogenous bioactive peptide that systemically exerts rapid and profound hypotensive and bradycardic activities and parasympathomimetic hemodynamic actions in vivo. Previous reports suggested that salusin-β is suppressed following physiological parasympathetic stimulation and appears to constitute a negative feedback relationship with the parasympathetic nervous system.

Purpose

We hypothesized that salusin-β is associated with the occurrence of VF/VT in BrS.

Methods

The study population consisted of 26 BrS patients with newly implantation of implantable cardioverter defibrillator (ICD) during 2003–2008. In all patients, salusin-β was measured in supine position after 20 minute rest. The date of salusin-β sampling was set as the registration point for this study. The VF/VT was defined as any episode of fatal ventricular tachyarrhythmia or any appropriate shock. In accordance with the presence or absence of VF/VT events within 5 years, all patients were divided into VF/VT group (n=6) and non-VF/VT group (n=20).Various clinical parameters were compared between the two groups. For analysis of autonomic nervous function, heart rate variability (HRV) and pupil function were evaluated.

Results

The mean age was 54±17 years old. There is no differences between the two groups in clinical parameters. In analysis of HRV, the high-frequency component (0.15–0.40 Hz; HF), low frequency component (0.04–0.15 Hz; LF) and the LF/HF ratio were analyzed over 24 h. LF/HF ratio was significantly lower over 24h in VF/VT groups in comparison with non-VF/VT groups [day-time; 1.8 (1.2–5.6) vs. 5.2 (3.4–8.8), p=0.048, night-time; 1.2 (1.1–1.3) vs. 3.9 (2.5–8.7), p=0.003]. Furthermore, in analysis of pupil function, right/left miosis ratio was higher in VT/VF groups in comparison with non-VT/VF groups [right pupil; 0.39 (0.37–0.59) vs. 0.34 (0.28–0.38), p=0.035, left pupil; 0.43 (0.36–0.50) vs. 0.33 (0.28–0.40), p=0.049]. In plasma total salusin-β levels, the VF/VT groups exhibited significantly lower than non-VF/VT groups (55.2±14.6 vs. 73.2±22.2, p=0.039, Figure).

Conclusions

Salusin-β was associated with the occurrence of VF/VT in Brugada syndrome. Salusin-β might be useful to identify high-risk patients for the occurrence of VT/VF events in Brugada syndrome.

Funding Acknowledgement

Type of funding source: None

Remote monitoring can predict lethal arrhythmic events through time-domain analysis of heart rate variability in patients with implantable cardioverter defibrillator

Background

We prospectively collected device and heart rate data, i.e. heart rate variability (HRV), through remote monitoring (RM) of patients with implantable cardioverter defibrillator (ICD). Several studies have demonstrated usefulness of RM in implanted device patients, however, reports concerning the predictors of lethal ventricular arrhythmias are limited.

Purpose

The objective was to identify the predictors of lethal arrhythmic events (VT/VF).

Methods

Thirty-three patients (mean age: 50 years) with ICDs [with functionality of HRV analysis] were divided into 2 groups [VT/VF(+), VT/VF(−)]. Clinical, device (ventricular lead impedance; amplitude of ventricular electrogram), and HRV data were compared between the 2 groups. As the index of time-domain HRV analysis, NN intervals-index (SDNNi) was calculated for every 5 minutes, and the mean, maximum, and minimum SDNNi during the 24-hour period were used.

Results

During the observation period (median 12 months), 10 patients experienced VT/VF events. In HRV data, the mean, max, and min SDNNi were higher in VT/VF(+) than VT/VF(−) group (132.9±9.3 v.s. 93.5±6.1, p=0.0013; 214.6±10.6 v.s. 167.0±7.0, p=0.0007; 71.2±7.5 v.s. 43.9±4.9, p=0.0047). The other parameters did not exhibit significant difference. On logistic regression analysis, the mean SDNNi of 100.1, max SDNNi of 185.0 and min SDNNi of 52.0 as cut-off values for prediction of VT/VF event demonstrated significant receiver operating characteristics (ROC) curves (AUC=0.86, p=0.0007; AUC=0.84, p=0.0005; AUC=0.78, p=0.0030). Furthermore, in cases of VT/VF(+) group, the max ΔSDNNi, i.e., difference from baseline SDNNi, and min ΔSDNNi in 7 and 28 days preceding VT/VF events exhibited time course changes in comparison with baseline values. They were significant predictors of VT/VF events (max ΔSDNNi cut-off: 46.8, AUC=0.91, p=0.0002; min ΔSDNNi cut-off: −42.4, AUC=0.88, p=0.0014).

Conclusion

Time-domain analysis of HRV through RM may help identify patients at high risk of lethal arrhythmic events, and predict occurrence of such arrhythmic events.

Funding Acknowledgement

Type of funding source: None

P1495Energy loss by right ventricular pacing: normal left ventricular function vs. hypertrophic cardiomyopathy

Background

Right ventricular (RV) pacing causes left ventricular (LV) dysfunction. On the other hand, RV pacing for hypertrophic obstructive cardiomyopathy (HOCM) is an established treatment. LV flow energy loss (EL) is a new hemodynamic index for assessing cardiac function. However, the impact of RV pacing on EL remains unknown.

Objective

The objective of this study was to investigate the EL by RV pacing on normal LV function and hypertrophic cardiomyopathy (HCM).

Methods

A total of 28 patients underwent echocardiography for EL assessment under AAI (without RV pacing) and DDD (with all RV pacing) mode. Among them, 16 were sick sinus syndrome (SSS) patients with normal LV function, and 12 were HCM patients. EL was calculated from color Doppler images using a vector flow mapping.

Results

There were no significant difference in patients' background parameters between the SSS and the HCM groups. In the SSS group, mean systolic EL was significantly increased from AAI to DDD mode (14.9 to 19.2 mW/m, P<0.01, Panel A), whereas diastolic EL was not changed from AAI to DDD mode (22.3 to 18.8 mW/m, P=0.12). In the HCM group, systolic mean EL was significantly decreased from AAI to DDD mode (29.9 to 22.5 mW/m, P<0.01, Panel B) irrespectively of with or without LV outflow obstruction, whereas diastolic mean EL was not changed from AAI to DDD mode (28.6 to 24.3 mW/m, P=0.47).

Change of flow energy loss

Conclusion

RV pacing increased mean systolic EL in normal LV function, but decreased in HCM with or without LV outflow obstruction. In the patients with HCM, the impact of RV pacing on EL is different compared with normal LV function.

Addition of Amide Proton Transfer Imaging to FDG-PET/CT Improves Diagnostic Accuracy in Glioma Grading: A Preliminary Study Using the Continuous Net Reclassification Analysis

BACKGROUND AND PURPOSE

Amide proton transfer imaging has been successfully applied to brain tumors, however, the relationships between amide proton transfer and other quantitative imaging values have yet to be investigated. The aim was to examine the additive value of amide proton transfer imaging alongside [¹⁸F] FDG-PET and DWI for preoperative grading of gliomas.

MATERIALS AND METHODS

Forty-nine patients with newly diagnosed gliomas were included in this retrospective study. All patients had undergone MR imaging, including DWI and amide proton transfer imaging on 3T scanners, and [¹⁸F] FDG-PET. Logistic regression analyses were conducted to examine the relationship between each imaging parameter and the presence of high-grade (grade III and/or IV) glioma. These parameters included the tumor-to-normal ratio of FDG uptake, minimum ADC, mean amide proton transfer value, and their combinations. In each model, the overall discriminative power for the detection of high-grade glioma was assessed with receiver operating characteristic curve analysis. Additive information from minimum ADC and mean amide proton transfer was also evaluated by continuous net reclassification improvement. P < .05 was considered significant.

RESULTS

Tumor-to-normal ratio, minimum ADC, and mean amide proton transfer demonstrated comparable diagnostic accuracy in differentiating high-grade from low-grade gliomas. When mean amide proton transfer was combined with the tumor-to-normal ratio, the continuous net reclassification improvement was 0.64 (95% CI, 0.036-1.24; P = .04) for diagnosing high-grade glioma and 0.95 (95% CI, 0.39-1.52; P = .001) for diagnosing glioblastoma. When minimum ADC was combined with the tumor-to-normal ratio, the continuous net reclassification improvement was 0.43 (95% CI, -0.17-1.04; P = .16) for diagnosing high-grade glioma, and 1.36 (95% CI, 0.79-1.92; P < .001) for diagnosing glioblastoma.

CONCLUSIONS

Addition of amide proton transfer imaging to FDG-PET/CT may improve the ability to differentiate high-grade from low-grade gliomas.

Temperature dependence of the single photon emission from interface-fluctuation GaN quantum dots

The temperature dependent single photon emission statistics of interface-fluctuation GaN quantum dots are reported. Quantum light emission is confirmed at temperatures up to ~77 K, by which point the background emission degrades the emission purity and results in a measured g⁽²⁾ (0) in excess of 0.5. A discussion on the extent of the background contamination is also given through comparison to extensive data taken under various ambient and experimental conditions, revealing that the quantum dots themselves are emitting single photons with high purity.

Acute Swine Model for Assessing Biocompatibility of Biomedical Interface Materials

We established an acute animal model for early, straightforward, and reproducible assessment of a biocompatible material interface. Bilateral femoral artery-to-vein shunts were created in 12 pigs: two tubes per shunt, the left two coated and the right two uncoated. We evaluated two groups: uncontrolled flow (UF; shunt flow unregulated) and controlled flow (CF; shunt flow ∼50 mL/min). For each case on each side, two shunts were evaluated: one for 1 h and the other for 3 h. Arterial blood gas and complete blood count were recorded at baseline, 1, and 3 h. Mean shunt flows were 532 ± 88 mL/min UF and 52 ± 8 mL/min CF. Differences in flow were much smaller in CF (0.5 mL/min; 1% of mean flow) than UF (24.8 mL/min; 5% of mean flow). In UF, significant changes occurred: in pH, from start of shunting through 1 h; in pO₂ and pCO₂, from start through 3 h. This swine model using bilateral femoral shunts with controlled blood flow provides a reliable, reproducible, easily implemented method by which to evaluate biocompatibility of device coatings at an early stage of investigation.