Microbiome-derived acidity protects against microbial invasion in Drosophila

Microbial invasions underlie host-microbe interactions resulting in pathogenesis and probiotic colonization. In this study, we explore the effects of the microbiome on microbial invasion in Drosophila melanogaster. We demonstrate that gut microbes Lactiplantibacillus plantarum and Acetobacter tropicalis improve survival and lead to a reduction in microbial burden during infection. Using a microbial interaction assay, we report that L. plantarum inhibits the growth of invasive bacteria, while A. tropicalis reduces this inhibition. We further show that inhibition by L. plantarum is linked to its ability to acidify its environment via lactic acid production by lactate dehydrogenase, while A. tropicalis diminishes the inhibition by quenching acids. We propose that acid from the microbiome is a gatekeeper to microbial invasions, as only microbes capable of tolerating acidic environments can colonize the host. The methods and findings described herein will add to the growing breadth of tools to study microbe-microbe interactions in broad contexts.

Microbiome derived acidity protects against microbial invasion in Drosophila

Microbial invasions underlie host-microbe interactions that result in microbial pathogenesis and probiotic colonization. While these processes are of broad interest, there are still gaps in our understanding of the barriers to entry and how some microbes overcome them. In this study, we explore the effects of the microbiome on invasions of foreign microbes in Drosophila melanogaster. We demonstrate that gut microbes Lactiplantibacillus plantarum and Acetobacter tropicalis improve survival during invasion of a lethal gut pathogen and lead to a reduction in microbial burden. Using a novel multi-organism interactions assay, we report that L. plantarum inhibits the growth of three invasive Gram-negative bacteria, while A. tropicalis prevents this inhibition. A series of in vitro and in vivo experiments revealed that inhibition by L. plantarum is linked to its ability to acidify both internal and external environments, including culture media, fly food, and the gut itself, while A. tropicalis diminishes the inhibition by quenching acids. We propose that acid produced by the microbiome serves as an important gatekeeper to microbial invasions, as only microbes capable of tolerating acidic environments can colonize the host. The methods described herein will add to the growing breadth of tools to study microbe-microbe interactions in broad contexts.

Initial experience of left bundle branch area pacing using stylet-driven pacing leads: a multicenter study

Funding Acknowledgements

Type of funding sources: None.

Background

Left bundle branch area pacing (LBBAP) has been performed exclusively using lumen-less pacing leads (LLL) with fixed helix design. This study is the first to explore in a multicenter population the safety and feasibility of LBBAP using stylet-driven leads (SDL) with extendable helix design.

Methods

This study prospectively enrolled all consecutive patients who underwent LBBAP for anti-bradycardia pacing or heart failure indications at 8 Belgian hospitals. LBBAP was attempted either using SDL or LLL delivered through dedicated delivery sheaths. Implant success, complications, procedural and pacing characteristics were recorded at implant and follow-up.

Results

The study enrolled 412 patients (mean age 74 ± 38 years, 44% female). LBBAP with SDL and LLL was successful in 334/353 (94%) and 52/59 (88%) respectively (p=0.058). Implant success for LBBAP using SDL varied from 93 to 100% among centers. Mean paced QRS duration and stimulus to left ventricular activation time were comparable for SDL and LLL (126 ± 21ms versus 125 ± 22ms, p=0.861 and 74 ± 17 and 75 ± 21ms, p=0.756). SDL LBBAP resulted in low pacing thresholds (0.6 ± 0.4V at 0.4ms), which remained stable at 1, 6 and 12 months of follow-up. Lead revisions for SDL LBBAP occurred in 5(1.4%) patients: 2 dislodgements at day 1, 1 late septal perforation at week 3, 1 Twiddler’s syndrome at 5 months, 1 lead fracture at 6 months.

Conclusion

This multicenter study confirms the safety and feasibility of LBBAP using SDL, which is characterized by high implant success, low complication rate and low and stable pacing thresholds.

Electrocardiographic analysis of left bundle branch area pacing induced right ventricular activation delay

Funding Acknowledgements

Type of funding sources: None.

Background

Left bundle branch area pacing (LBBAP) aims to capture the area of left bundle branch, resulting in fast activation of the left ventricle (LV) but delayed right ventricular (RV) activation. During intrinsic cardiac conduction, delayed RV activation results on the electrocardiogram (ECG) in a right bundle branch block (RBBB) pattern and is generally considered benign. As such, LBBAP-induced delayed RV activation is thought not to be harmful. However, to what extent left and right ventricular activation times during LBBAP resembles that of healthy individuals with acquired RBBB is currently not known.

Methods

Individuals with incomplete RBBB (iRBBB), complete RBBB (cRBBB) and LBBAP were included. Standard twelve lead electrocardiograms (ECG) were stored and analysed digitally using the MUSE ECG database. QRS duration was measured as global QRS duration. Left and right ventricular activation times were estimated by R-wave peak time in lead V6 (V6RWPT) and R’ peak time in lead V1 (V1RWPT), respectively. Delayed RV activation was further characterized by duration and area of R’ wave in lead V1.

Results

Paced QRS duration during LBBAP (n=86) measured 129±15ms whereas QRS duration of iRBBB (n=422) and cRBBB (n=223) individuals measured 103±8ms and 142±17ms respectively (p<0.001). V6RWPT during LBBAP (47±15ms) was significantly longer than V6RWPT in iRBBB (40±5ms) and cRBBB (39±7ms) (p<0.001). With LBBAP, V1RWPT (83±15ms) became delayed compared to iRBBB (74±9ms, p< 0.001), but remained shorter in comparison to cRBBB (98±17ms, p<0.001). Patients with LBBAP were further characterized by V1 R’ duration and R’ area which were shorter and smaller compared to cRBBB but similar to iRBBB individuals.

Conclusion

LBBAP-induced delayed RV activation resembles electrocardiographically more closely to the delayed RV activation as seen in individuals with incomplete rather than complete RBBB. Left ventricular activation times remain slightly prolonged during LBBAP as compared to RBBB individuals.

Defining left bundle branch block according to the new 2021 European Society of Cardiology criteria

Correctly diagnosing left bundle branch block (LBBB) is fundamental, as LBBB occurs frequently in heart failure and may trigger a vicious cycle of progressive left ventricular dysfunction. Moreover, a correct diagnosis of LBBB is pivotal to guide cardiac resynchronisation therapy. Since the LBBB diagnostic criteria were recently updated by the European Society of Cardiology (ESC), we assessed their diagnostic accuracy compared with the previous ESC 2013 definition. We further discuss the complexity of defining LBBB within the context of recent insights into the electromechanical pathophysiology of LBBB.

Progressive left ventricular electro-mechanical remodelling in presence of left bundle branch block

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Research Foundation Flanders (FWO)

Introduction

Recent cross-sectional studies suggest a relationship between persisting left bundle branch block (LBBB) and the extent of left ventricular (LV) electro-mechanical remodelling over time. However, when patients are referred for cardiac resynchronization therapy (CRT), temporal data during the sub-clinical phase of disease are often missing. A longitudinal study using an animal model would improve our understanding of the relationship between the onset of LBBB and the electro-mechanical remodelling.

Purpose

To investigate the progressive remodelling that develops over time in an animal model of LBBB.

Methods

Fifteen sheep were subjected to rapid DDD pacing (180 bpm; leads on right atrium and right ventricular free wall) in order to induce a LBBB-like conduction delay. All animals underwent an 8-week pacing protocol, whereas 5 of them were subjected to 16 weeks of pacing in total. Echocardiographic speckle tracking was used to assess circumferential strain of the septal and lateral wall. Septal and lateral wall thickness were measured at end-diastole. Cardiac magnetic resonance imaging was used to determine LV volumes and ejection fraction (LVEF). Examinations took place at baseline (before and after start of pacing), and after 8 and 16 weeks of pacing. All examinations were performed at a physiologic heart rate of 110 bpm.

Results

At baseline, DDD pacing induced an increase in QRS duration (+83%, p < 0.0001) and LBBB-like mechanical dyssynchrony, with mild early-systolic notching and preserved systolic shortening of the septal wall. Early lateral wall pre-stretch was followed by increasing systolic shortening. No acute changes in LV end-diastolic volume, LVEF or septal or lateral wall thickness were observed (all p > 0.05). After 8 weeks of DDD pacing, mechanical dyssynchrony worsened: septal notching increased, followed by reduced systolic shortening. After 16 weeks, the initial septal shortening was followed by profound stretching throughout systole. Lateral wall shortening was reduced compared to baseline (p < 0.05). QRS duration progressively increased by +15% (week 8) and +26% (week 16) (all p < 0.001). End-diastolic volumes had increased by +38% (week 8) and +74% (week 16), whereas LVEF had decreased by –35% (week 8) and –55% (week 16) (all p < 0.001). Septal wall thickness had reduced by –18% (week 8) and –29% (week 16), while lateral wall thickness had increased by +13% (week 8) and +24% (week 16) (all p < 0.05).

Conclusion

A persisting LBBB induces progressive changes in LV deformation patterns, and triggers morphological and electrical remodelling, strengthening the concept of LBBB-induced cardiomyopathy. In the clinic, patients with mild dysfunction should be closely monitored for potential disease progression in order to treat dyssynchrony as soon as guideline indications are reached. Further studies need to show if earlier CRT-implantation might prevent further LV deterioration. Abstract Figure.  Abstract Figure.

Strain-based staging classification of left bundle branch block-induced cardiac remodeling predicts reverse remodeling after cardiac resynchronization therapy

Background

Left bundle branch block (LBBB)-induced adverse remodeling is a gradual but largely unknown process, causing a variable degree of left ventricular (LV) dysfunction and response to cardiac resynchronization therapy (CRT). In LBBB patients with septal flash (SF), an electro-mechanical continuum of different speckle-tracking strain patterns was observed, with each pattern tightly correlating with the degree of LV remodeling and dysfunction (1) (Figure 1).

Purpose

In this study, we investigated the relationship between the staged LBBB strain patterns in CRT-eligible patients and their prediction with respect to reverse remodeling and clinical outcome.

Methods

This study enrolled CRT patients from the PREDICT-CRT study population (2). Inclusion criteria were LV ejection fraction (LVEF) ≤35%, QRS duration ≥120 ms, NYHA class II–IV, absence of right ventricular pacing and availability of speckle tracking strain imaging. All patients underwent an echocardiographic examination before and 12 months after CRT implant. LV volumes, strain and dyssynchrony were assessed. Mid-septal longitudinal strain curves were classified into 5 patterns (LBBB-0 through LBBB-4; Figure 1). Primary endpoint was all-cause mortality.

Results

The study involved 250 patients (mean age 64±10 years; 79% men) with a mean LVEF of 26±7%. LBBB was present in 220 (89%) patients and 206 (82%) patients had SF. Prior to CRT implant, a LBBB-0 pattern was observed in 33 (13%), LBBB-1 in 33 (13%), LBBB-2 in 39 (16%), LBBB-3 in 44 (18%) and LBBB-4 in 101 (40%) patients. Patients with LBBB-3 and -4 patterns more frequently had LBBB, lower LVEF, increased mechanical dyssynchrony and more prominent SF (p<0.001 for all) compared with patients with LBBB-0, -1 and -2 patterns. Across the stages, CRT resulted in a gradual volumetric response, ranging from no response in stage LBBB-0 patients (ΔLV end-systolic volume +7±33%; ΔLVEF −2±9%) to super-response in stage LBBB-4 patients (ΔLV end-systolic volume −40±29%; ΔLVEF +15±13%) (p<0.001 for all). Interestingly, following reverse remodeling, the LV function of stage LBBB-2, -3 and -4 patients improved to a similar LVEF of 38% (p=1.000) in this cohort. Patients in stage LBBB-0 had a significantly less favorable five-year outcome compared to those in stage LBBB≥1 (log-rank p=0.003). There was no difference in long-term outcome between stage LBBB-1 to −4 patients (log-rank p=0.510).

Conclusion

Strain-based LBBB staging predicts the extent of LV reverse remodeling in CRT patients. CRT did not translate into improved absolute survival in the more advanced stages, but the observed gradual volumetric response suggests that CRT corrects the LBBB-induced mortality.

Funding Acknowledgement

Type of funding sources: None. Figure 1

Sequential left ventricular electro-mechanical changes in presence of left bundle branch block

Introduction

Recent cross-sectional studies suggest a relationship between persisting left bundle branch block (LBBB) and the extent of left ventricular (LV) electro-mechanical alterations over time. When patients are referred for cardiac resynchronization therapy (CRT), temporal data during the sub-clinical phase of disease is often missing. A longitudinal study using an animal model would provide a better understanding of the relationship between the onset of LBBB and the electro-mechanical changes.

Purpose

To investigate the sequential alterations in LV structure and function that develop over time in an animal model of LBBB.

Methods

Thirteen sheep were subjected to rapid DDD pacing (180 bpm; leads on right atrium and right ventricular free wall) in order to induce a LBBB-like conduction delay. All animals underwent an 8-week pacing protocol, whereas 4 of them were subjected to 16 weeks of pacing in total. Echocardiographic speckle tracking was used to assess circumferential strain of the septal and lateral wall. Septal and lateral wall thickness were measured at end-diastole. Cardiac magnetic resonance imaging was used to determine LV volumes and ejection fraction (LVEF). Examinations took place at baseline (before and after start of pacing), and after 8 and 16 weeks of pacing. All examinations were performed at a physiologic heart rate of 110 bpm.

Results

At baseline, DDD pacing induced an increase in QRS duration (+85%, p<0.0001) and LBBB-like mechanical dyssynchrony, with mild early-systolic notching and preserved systolic shortening of the septal wall. The lateral wall demonstrated early pre-stretch followed by increasing systolic shortening. No acute changes in LV end-diastolic volume, LVEF or septal or lateral wall thickness were observed (all p>0.05). After 8 weeks of DDD pacing, mechanical dyssynchrony worsened: septal notching increased, followed by reduced systolic shortening. After 16 weeks, the initial septal shortening was followed by profound stretching throughout systole. Lateral wall systolic shortening was reduced compared to baseline. QRS duration increased further by +12% (week 8) and +20% (week 16) (all p<0.001). End-diastolic volumes had increased by +39% (week 8) and +72% (week 16), whereas LVEF had decreased by −48% (week 8) and −56% (week 16) (all p<0.001). Septal wall thickness had reduced by −24% (week 8) and −33% (week 16), while lateral wall thickness had increased by +21% (week 8) and +30% (week 16) (all p<0.05).

Conclusion

A persisting LBBB-like conduction delay induces sequential changes in LV deformation patterns, and triggers morphological and electrical remodelling. These changes are similar to those observed in patients with LBBB and different degrees of LV dysfunction. Our data suggest a continuum due to the progression of LBBB-induced LV disease. In the clinic, patients with mild dysfunction should be closely monitored in order to treat dyssynchrony as soon as guideline indications are reached.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): This work was supported by a KU Leuven research grant

Aortic valve implantation-induced conduction block as a framework towards a uniform electrocardiographic definition of left bundle branch block

Introduction

New-onset left bundle branch block (LBBB) following transcatheter or surgical aortic valve replacement (LBBB_AVI) implies a proximal pathogenesis of LBBB. This study compares electrocardiographic characteristics and concordance with LBBB definitions between LBBB_AVI and non-procedure-induced LBBB controls (LBBB_control).

Methods

All LBBB_AVI patients at Ghent University Hospital between 2013 and 2019 were enrolled in the study. LBBB_AVI patients were matched for age, sex, ischaemic heart disease and ejection fraction to LBBB_control patients in a 1:2 ratio. For inclusion, a non-strict LBBB definition was used (QRS duration ≥ 120 ms, QS or rS in V1, absence of Q waves in V5-6). Electrocardiograms were digitally analysed and classified according to three LBBB definitions: European Society of Cardiology (ESC), Strauss and American Heart Association (AHA).

Results

A total of 177 patients (59 LBBB_AVI and 118 LBBB_control) were enrolled in the study. LBBB_AVI patients had more lateral QRS notching/slurring (100% vs 85%, p = 0.001), included a higher percentage with a QRS duration ≥ 130 ms (98% vs 86%, p = 0.007) and had a less leftward oriented QRS axis (−15° vs −30°, p = 0.013) compared to the LBBB_control group. ESC and Strauss criteria were fulfilled in 100% and 95% of LBBB_AVI patients, respectively, but only 18% met the AHA criteria. In LBBB_control patients, concordance with LBBB definitions was lower than in the LBBB_AVI group: ESC 85% (p = 0.001), Strauss 68% (p < 0.001) and AHA 7% (p = 0.035). No differences in electrocardiographic characterisation or concordance with LBBB definitions were observed between LBBB_AVI and LBBB_control patients with lateral QRS notching/slurring.

Conclusion

Non-uniformity exists among current LBBB definitions concerning the detection of proximal LBBB. LBBB_AVI may provide a framework for more consensus on defining proximal LBBB.

Supplementary Information

The online version of this article (10.1007/s12471-021-01565-8) contains supplementary material, which is available to authorized users.

P309Aortic valve implantation-induced bundle branch block as a framework towards a more uniform electrocardiographic definition of left bundle branch block

INTRODUCTION

The electrocardiographic (ECG) pattern of true left bundle branch block (LBBB) has not been fully clarified and various definitions of LBBB exist. New-onset LBBB after transcatheter (TAVR) or surgical (SAVR) aortic valve replacement implies a proximal pathogenesis of LBBB and thus may provide a reference to characterize and define true LBBB.

PURPOSE

This study compares ECG characteristics in aortic valve implantation-induced LBBB (AVI-LBBB) to a non-procedural-induced LBBB control group (co-LBBB) in order to set a more homogenous definition for true LBBB.

METHODS

The study enrolled all patients with new-onset TAVR- and SAVR-induced LBBB between 2013 and 2019. AVI-LBBB was defined as new-onset persistent LBBB occurring within 24h after TAVR or SAVR. Patients were matched for age, sex, ischemic heart disease and left ventricular systolic function to randomly selected co-LBBB patients in a 1:2 ratio. For inclusion in both groups, a non-strict LBBB definition was used (QRSD ≥120ms, QS or rS in lead V1, absence of Q wave in leads V5-6). ECG characteristics were digitally analysed by the MUSE algorithm and confirmed by two experts. All ECG recordings were classified according to 4 different LBBB definitions: MADIT, European Society of Cardiology (ESC), Strauss and American Heart Association (AHA).

RESULTS

59 patients with AVI-LBBB (34 TAVR, 25 SAVR, median age 82 years, 42% male) were compared to 118 matched co-LBBB patients.

All patients with AVI-LBBB presented with QRS notching/slurring in the lateral leads, whereas this was present in only 85% of the co-LBBB group (p = 0.001). QRS duration (148ms vs 145ms, p = 0.074) and R wave peak time (58ms vs 62ms, p = 0.065) were not significantly different among both groups. AVI-LBBB was characterized by a more rightward QRS axis (-15° vs -30°, p = 0.013). When comparing AVI-LBBB to LBBB controls with QRS notching/slurring, a comparable QRS axis was observed.

Almost all AVI-LBBB patients met the MADIT (98%), ESC (100%) and Strauss (95%) definition. Only 18% of patients met the AHA definition, because of the low combined presence of QRS notching/slurring in all 4 lateral leads (54%) and because only 27% of patients had an R wave peak time &gt;60ms in both leads V5-6.

In the co-LBBB group, adherence to the different definitions was significantly lower compared to the AVI-LBBB group: MADIT 86% (p = 0.007), ESC 85% (p = 0.001), Strauss 68% (p &lt; 0.001) and AHA 7% (p = 0.035). Lower presence of lateral notching/slurring and more patients with smaller QRS duration (QRS duration ≥130ms, 86% vs 98%, p = 0.007) in the co-LBBB group explain these results.

CONCLUSIONS

Discordance exists between various definitions in scoring AVI-LBBB. Our data show that presence of QRS notching/slurring in the lateral leads is a crucial feature of proximal LBBB, rather than QRS duration and R wave peak time. The AVI-LBBB population provides a framework towards a more uniform definition and criteria for assessing true, proximal LBBB.

P782 Septal flash is a prevalent and early dyssynchrony marker in transcatheter aortic valve replacement-induced left bundle branch block

CONCLUSION

SF as dyssynchrony marker develops early after TAVR-induced LBBB and is much more prevalent than the classical strain-based dyssynchrony pattern and IVMD.

Our findings from the control population suggest that progressive LBBB-induced LV remodeling (septal thinning and relative lateral thickening) may be required for a ‘classical dyssynchrony strain pattern’ or significant IVMD to occur in TAVR-LBBB patients, but longitudinal follow-up studies in TAVR-LBBB patients are required as proof-of-concept.

Abstract P782 Figure 1

P290 Differences in cardiac dimensions in mitral valve prolapse with or without Barlow phenotype

Background

Mitral valve prolapse (MVP) is a common cause of chronic mitral regurgitation (MR). Barlow’s disease (BD) and fibro-elastic deficiency (FED) are two major entities of MVP affecting the connective tissue of the mitral valve, but both have a different underlying pathophysiology and phenotype. In some connective tissue diseases (CTD), it has been suggested that ventricular dysfunction occurs despite absence of MR, suggesting that CTD directly involve the myocardium. We therefore investigated whether patients with BD have different cardiac dimensions compared to FED, after correcting for MR severity grade.

Methods

134 patients with MVP and chronic MR were prospectively included. MR was graded carefully by echocardiography using a multi-parametric approach. The morphology of the mitral valve prolapse was specified as definite Barlow (n = 45) or non-Barlow (n = 89; FED, flail leaflet or unspecified etiology) by two experienced echocardiographers.

Results

In our cohort, MR was significantly more severe in the non-Barlow group compared to typical BD group (regurgitant volume (RV) 51 vs 33 ml, p = 0.021; right ventricular systolic pressure, 40 vs 34 mmHg, p= 0.05, left atrial volume index, 51 vs 42 ml/m², p = 0.07, respectively).

However, there was a trend towards higher left ventricular end-diastolic diameter index (LVEDDi, 27.7 vs 29 mm, p = 0.07) and a significantly higher end-diastolic volume index (LVEDVi, 62 vs 71 ml/m², p= 0.02) in the Barlow group, despite similar ejection fractions and much less MR in the Barlow group. This resulted in a significantly higher RV/LVEDV ratio in the non-Barlow group compared to the Barlow group (42% vs 23%, p = 0.001). Similarly, the LA volume/LVEDV ratio was significantly lower in the Barlow cohort (63 vs 79%, p= 0.026). There were no significant differences in aortic dimensions between groups.

Conclusions

We describe for the first time that compared to non-Barlow (mostly FED), patients with MVP due to typical Barlow disease have larger ventricular dimensions and volumes, which are disproportionate to the degree of MR. We therefore hypothesize that the connective tissue alterations in these patients may also involve the myocardium resulting in LV dilation independent of MR. Further investigation and clinical implications of these findings is mandatory.

6119Correction of transcatheter aortic valve replacement induced left bundle branch block by His bundle pacing

Background

Left bundle branch block (LBBB) occurs frequently after transcatheter aortic valve replacement (TAVR) and is associated with increased risk of permanent pacemaker implantation, heart failure hospitalization and sudden cardiac death. This pilot study explored the feasibility of TAVR-induced LBBB correction with His bundle pacing (HBP).

Methods

Patients with TAVR -induced LBBB and postoperative need for permanent pacemaker implant were planned for electrophysiology study and HBP. Patients with persistent high degree AV-block were excluded. HBP was performed using the Select Secure pacing lead, delivered through a fixed curve or a deflectable sheath. Successful HBP was defined as correction of LBBB by selective or non-selective HBP with LBBB correction thresholds less than 3.5V at 1.0ms at implant.

Results

The study enrolled 6 patients (mean age 85±2.5 years, 50% male). Mean QRS duration was 152±10ms, PR-interval 212±12ms AH-interval 166±16ms and HV-interval 62±12ms. Successful HBP was achieved in 5/6 (83%) patients. Mean QRS duration decreased from 153±11ms to 88±14ms (p=0.002). At implantation, mean threshold for LBBB correction was 1.6±1.0V (unipolar) and 2.2±1.3V (bipolar) at 1.0ms. Periprocedural, two complete AV-blocks occurred, both spontaneously resolved by the end of the procedure. Thresholds remained stable at 1 month follow up: 1.8±1.0V (unipolar) and 2.3±1.5V (bipolar) at 1.0ms.

Figure 1

Conclusion

Permanent His bundle pacing can safely correct TAVR-induced LBBB in the majority of patients. Further studies are needed to assess potential benefits of His bundle pacing over conventional right ventricular pacing in this population.

Alcohol-related emergency department admissions among adolescents in the Ghent and Sint-Niklaas areas

Alcohol abuse is a major health concern. The aim of this retrospective study was to analyse the alcohol-related emergency department (ED) admissions among adolescents in all hospitals of distinct areas during a 1-year period. In each hospital, all ED patients with a blood alcohol concentration (BAC) of at least 0.5 g/l were surveyed in a standardised way. Of the 3918 included patients, only 146 (3.7%) were < 18  years. The male-to-female ratio was 1.5:1. There was a strong preponderance of weekend and night time admissions. Most of the patients were transported by ambulance (77% of 138 patients with information on this item). The main reason for ED admittance was depressed level of consciousness (64%), trauma (12%), vomiting and/or abdominal pain (12%), agitation or aggression (4%), syncope (4%) and psychological problems (4%). The context of the alcohol intoxication was related to some kind of festivity in 85%, mental problems in 14% and chronic abuse in 1%. Median BAC values (and range) were 2.08 g/l (0.73-3.70 g/l) for boys and 1.51 g/l (0.73-2.90 g/l) for girls. Most patients (87%) could be discharged home within 24  hours. Our study confirms that problematic alcohol use leading to ED admissions starts in adolescence. Although the numbers of cases below 18 years are low when compared to adults, the phenomenon is alarming as it is associated with substantial health problems. Therefore, Belgium urgently needs a global national alcohol plan, with youngsters being one of the target groups.

Exploration of trabecular bone nonlinear elasticity using time-of-flight modulation

Bone tissue contains microcracks that may affect its mechanical properties as well as the whole trabecular structure. The relationship between crack density and bone strength is nevertheless poorly understood. Linear ultrasound techniques being almost insensitive to the level of damage, we propose a method to measure acoustic non- linearity in trabecular bone using time-of-flight modulation (TOFM) measurements. Ultrasonic short bursts times-of- flight (TOF) are modulated as a result of nonlinear interaction with a low-frequency (LF) wave in the medium. TOF variations are directly related to elastic modulus variations. Classical and nonclassical nonlinear parameters beta, delta, and alpha can be derived from these measurements. The method was validated in materials with classical, quadratic, nonlinear elasticity. In dense trabecular bone region, TOFM related to classical, quadratic, nonlinear elasticity as a function of the LF pressure exhibits tension-compression asymmetry. The TOFM amplitude measured in dense areas of trabecular bone is almost one order of magnitude higher than in a low-density area, but the linear parameters show much smaller variations: 5% for ultrasound propagation velocity and 100% for broadband ultrasonic attenuation (BUA). In high-density trabecular bone regions, beta depends on the LF pressure amplitude and can reach 400 at 50 kPa.

Hematologic reconstitution following high-dose and supralethal chemoradiotherapy using stored, noncryopreserved autologous hematopoietic stem cells

Although cryopreservation is the standard for autotransplantation, it has logistic and financial disadvantages in undeveloped countries such as Colombia. In 47 patients, peripheral blood was refrigerated at 4 degrees C up to 144 h before autotransplantation. For mobilization, 27 men and 20 women of median age 37 years affected with hematologic malignancies received G-CSF. The 17 patients in Group 1 showed pre-refrigeration CFU-GM of 2.62 x 10(5)/kg (range 0.36 to 16.6 x 10(5)/kg) and at re-infusion, 1.36 x 10(5)/kg (range 0 to 6.32 x 10(5)/kg) of 83% viability (range, 78% to 96%). These patients showed >0.5 x 10(9)/L granulocytes on day +11 (range, 9 to 15) and >20 x 10(9)/L platelets on day +16 (range, 11 to 44). The 25 patients in Group 2 showed CD34 of 3.9 x 10(6)/kg (range, 0.16 to 9 x 10(6)/kg) and mononuclear cell count (MNC) of 8.7 x 10(8)/kg, reaching >0.5 x 10(9)/L granulocytes at day +13 (range, 10 to 17) and >20 x 10(9)/L on day +15 (range, 14 to 20). Among the 5 patients in Group 3, the average of MNC of 12.7 x 10(8)/kg was reached and >0.5 x 10(9)/L granulocytes on day 11 (range, 10 to 16) and >20 x 10(9)/L on day 14 (range, 10 to 18). No differences were observed between the groups. Refrigeration of stem cells appears to be a simple, effective, and inexpensive method that should be considered for autotransplants within a few days of harvesting when resources are limited for long-term storage.

Separation efficiency of a wood dust collector-field measurement using a fluorescent aerosol

Given the dangerous nature of the dust emitted in the wood industry, the quality of the recycled air in the work premises after cleaning must be strictly controlled.A method of measuring the efficiency of a wood dust collector as a function of the particle diameter has been developed using a fluorescein tracer aerosol generated upstream of the equipment. The separation efficiency is determined from the particle size mass distribution of the tracer, both upstream and downstream, measured by means of two cascade impactors. The mass efficiency measured by tracer technique was compared on a test rig to the number efficiency measured using a reference method based on optical counting. The agreement between the two efficiencies is quite good; nevertheless, the tracer method leads to results that are slightly below those obtained using the reference method. The method was applied to measure the efficiency of a 11 500 m(3) h(-1) wood dust collector. The results are presented along with those obtained from a sample of plane filter media making up the bags of the dust collector.

Enzyme alterable alkylating agents. 8. Clinical trials with intra-arterial infusion of an alkylating agent with a half-life of 0.2 second

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