High-density volumetric super-resolution microscopy

Volumetric super-resolution microscopy typically encodes the 3D position of single-molecule fluorescence into a 2D image by changing the shape of the point spread function (PSF) as a function of depth. However, the resulting large and complex PSF spatial footprints reduce biological throughput and applicability by requiring lower labeling densities to avoid overlapping fluorescent signals. We quantitatively compare the density dependence of single-molecule light field microscopy (SMLFM) to other 3D PSFs (astigmatism, double helix and tetrapod) showing that SMLFM enables an order-of-magnitude speed improvement compared to the double helix PSF by resolving overlapping emitters through parallax. We demonstrate this optical robustness experimentally with high accuracy ( > 99.2 ± 0.1%, 0.1 locs μm-2) and sensitivity ( > 86.6 ± 0.9%, 0.1 locs μm-2) through whole-cell (scan-free) imaging and tracking of single membrane proteins in live primary B cells. We also exemplify high-density volumetric imaging (0.15 locs μm-2) in dense cytosolic tubulin datasets.

Contour, a semi-automated segmentation and quantitation tool for cryo-soft-X-ray tomography

Cryo-soft-X-ray tomography is being increasingly used in biological research to study the morphology of cellular compartments and how they change in response to different stimuli, such as viral infections. Segmentation of these compartments is limited by time-consuming manual tools or machine learning algorithms that require extensive time and effort to train. Here we describe Contour, a new, easy-to-use, highly automated segmentation tool that enables accelerated segmentation of tomograms to delineate distinct cellular compartments. Using Contour, cellular structures can be segmented based on their projection intensity and geometrical width by applying a threshold range to the image and excluding noise smaller in width than the cellular compartments of interest. This method is less laborious and less prone to errors from human judgement than current tools that require features to be manually traced, and does not require training datasets as would machine-learning driven segmentation. We show that high-contrast compartments such as mitochondria, lipid droplets, and features at the cell surface can be easily segmented with this technique in the context of investigating herpes simplex virus 1 infection. Contour can extract geometric measurements from 3D segmented volumes, providing a new method to quantitate cryo-soft-X-ray tomography data. Contour can be freely downloaded at github.com/kamallouisnahas/Contour.

Automatic measurement of LV wall thickness from 2D cardiac echocardiography

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): PIC from European Union"s Horizon 2020 Marie Skłodowska-Curie Actions ITN

Background

The wall thickness of the left ventricle (LV) is an important parameter in the diagnosis of hypertension and more specifically in hypertrophic cardiomyopathy. A user-dependent manual assessment of distances on 2D echocardiographic images is the current clinical gold-standard.

Purpose

The automation of LV wall thickness measurements in 2D echocardiography in order to improve robustness and reduce time of clinical reports where wall thickness is required, such as hypertrophy and the presence of Basal Septal Hypertrophy (BSH)(1).

Methods

A dataset of 4-chamber (4CH) echocardiograms on 118 patients with a diagnosis of hypertension (2) is used for this study. The images were segmented automatically (3) extracting the blood pool and the myocardium. Based on the curvature of the complete myocardial contour, the valve annular regions are removed leaving the endocardial and the epicardial walls as independent structures. The wall thickness along the myocardium is calculated as the distance from each endocardial border pixel to the closest epicardial point  (see Figure 1). A high pass gaussian filter was applied to remove high frequency noise. Ultimately, the basal-to-mid septal wall thickness ratio that defines BSH (ratio ≥ 1.4) was computed as the maximal of basal-septal segment divided by minimum of mid-septal segment. In order to validate the method for BSH detection, the wall thickness septal ratio was carefully measured by a clinical expert following the guidelines (2). The statistical agreement was accessed via linear correlation and Bland-Altman analysis.

Results

The automatic assessment of LV wall thickness along the myocardium is feasible in 2D echocardiography. The septal ratio showed an excellent agreement with manual measurements (R2 = 0.94, bias=-0.01, see Figure 2), leading to a detection of BSH in n = 19 vs the n = 18 detected manually (1 false-negative and 2 false-positives). In comparison to the intra and inter-observer variabilities of 12% and 42% respectively in the manual measurement (4), the automatic method had no variability for a given image acquisition.

Conclusions

The automatic measurement of myocardial wall thickness from a 2D echocardiographic images is accurate and reproducible. The implementation of the methodology in clinical practise has the potential to improve and automate the assessment of hypertrophic cardiac conditions. Abstract Figure. Pipeline for automatic measurement of WT  Abstract Figure. Agreement of BSH WT ratio

Cardiac function during COVID-19 intensive care unit hospitalisation - deformation analysis and outcomes

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Horizon 2020 European Commission Project H2020-MSCA-ITN-2016

Background

Although the cardiac burden of COVID-19 has been demonstrated, follow-up imaging studies are scarce. The aim was to use speckle-tracking deformation imaging (STE) to prospectively assess cardiac function during intensive care unit (ICU) hospitalisation, comparing ventricular and atrial function of COVID-10 patients that died and those that were discharged.

Methods

In a single-centre, COVID-19 patients (n = 41) (71% male, aged 65 ± 11 years) were prospectively followed with echocardiography as part of ICU treatment. The left and right ventricles (LV, RV, respectively) were studied with STE in the 4-chamber cardiac view. The endpoint was defined as death or ICU discharge. Average values of the strain parameters from the first and final scans in the ICU, respectively, were calculated for the two outcome groups.

Results

Endpoint was not reached in 15% (n = 6) at the time of analysis. The remaining patients (n = 32) were 69% male, aged 66 (interquartile range (IQR) 60-72) years, and with an ICU mortality 26% (n = 9). The median spent in ICU was 24 (IQR 15-43) days. On average, echocardiography was performed three times during ICU hospitalisation, amounting to 103 examinations. The changes in cardiac strain are shown in Table 1. The change in LV longitudinal strain during ICU hospitalisation is shown in Figure 1.

Conclusion

Worsening of LV strain and lack of improvement of RV strain is linked to higher mortality in the ICU. The assessment of cardiac function might contain prognostic information in COVID-19 patients that are admitted to the ICU.

	Patients discharged from thee OCU (n = 23)	Patients that died in the ICU (n = 9)	P value
Initial echo in the ICU
LV strain, % (IQR)	18.00 (15.6-19.95)	14.4 (10.56-20.42)	0.158
RV strain, % (IQR)	16.00 (14.70-20.05)	15.50 (10.38-23.70)	0.712
Final echo before discharge
LV strain, % (IQR)	17.35 (15.13-18.98)	13.20 (10.75-15.40)	0.007
RV strain, % (IQR)	17.65 (16.83-19.60)	15.75 (10.68-20.43)	0.438

ICU - intensive care unit; IQR-inter-quartile range

P735 Septal curvature - a novel, semi-automated parameter to aid in recognition of basal septal hypertrophy in arterial hypertension

Funding Acknowledgements

Horizon 2020 European Commission Project MSCA-ITN-2016 (764738), Grant from Fundacio La Marató de TV3 (040310).

Background and aim

Localized basal septal hypertrophy (BSH) is a known marker of increased afterload and localized deformation impairment, and can be seen in one-fifth of patients with arterial hypertension. Although there is variability in the classification, BSH is mainly defined from ratios between several wall thickness measurements. We hypothesize that the curvature of the septum is reflective of localized hypertrophy and will be significantly increased in patients with BSH. Speckle tracking endocardial delineations of the left ventricle (LV) can be used to quantify curvature, with the potential to create a novel, semi-automatized parameter for recognition of patients with an increased impact of afterload on cardiac structure and function.

Methods

An echocardiogram was performed on a total of 149 patients with a diagnosis of long-standing hypertension, treated with at least one antihypertensive drug and on 19 healthy age and sex-matched controls. The interventricular septum thickness was measured at basal and mid-level in the parasternal long axis (PLAX) and 4-chamber (4C) views. BSH was identified from a two-part criterion: both a positive visual assessment of an abrupt change in septal thickness seen in the 4C or PLAX views and a basal to mid-septal ratio ≥ 1.4. A dedicated software for speckle tracking was used to trace the endocardial border of the LV in 4C and 3C view. In post-analysis, we quantified the maximal curvature of the antero- and inferoseptal segments from the exported myocardial contour. Curvature, measured in m-1, was defined as the reciprocal value of the radius of the circle fitted into the curve defined by three subsequent neighboring points in the myocardial contour. Curvature was considered negative if the curve was convex with respect to the LV long-axis.

Results

Using septal wall thickness measurements, 19% (n = 28) of hypertensive patients were classified as having BSH, whereas all healthy controls had normal geometry. Basal antero- and inferoseptal wall thickness was significantly increased in the BSH group, which was coupled with regional deformation impairment (basal inferoseptum, controls vs. non-BSH vs. BSH: 16.1 ± 2.33 vs. 15.14 ± 2.8 vs. 13.02 ± 2.98 %, p < 0.001). The curvature of the basal inferoseptum was significantly higher in the BSH group (controls vs. non-BSH vs BSH: -23.4 (-27.2, -10.9) vs. -28.3 (-40.2, -19.3) vs. -50.5 (-66.8, -33.9) m-1, p < 0.001) (Figure 1), with the same trend seen in the basal anteroseptum. The inferoseptal curvature showed a moderately strong correlation with the inferoseptal basal-to-mid wall thickness ratio (R = 0.527, p <0.001).

Conclusion

Increased septal curvature is an easily quantifiable, single-value, semi-automated parameter reflective of localized thickening that could easily be incorporated into the output of the LV speckle tracking workflow, possibly aiding in the recognition of hypertensive patients in need of a closer clinical follow-up.

Abstract P735 Figure 1

155 Myocardial work in hypertension and mitral regurgitation- insights from non-invasive assessment of left ventricular pressure-strain relations

Funding Acknowledgements

Horizon 2020 European Commission Project H2020-MSCA-ITN-2016 (764738), Grant from Fundacio La Marató de TV3 (040310)

Background and aim

Non-invasive left ventricular (LV) pressure estimates and speckle-tracking deformation curves can be used to quantify an index of myocardial work (MWI) which may offer insight into the early changes and work distribution in hypertension (HTN) and mitral regurgitation (MR) – cardiac diseases related to pressure and volume overload. The aim is to assess segmental strain and MW indices in patients with HTN, MR, and in healthy controls.

Methods

An echocardiogram was performed in 73 participants: 31 patients with a diagnosis of long-standing HTN with signs of LV hypertrophy, 22 patients with MR without hypertension, and 20 healthy age- and sex-matched controls. LV speckle-tracking was performed in 4C, 2C, and 3C apical views. MWI was calculated between mitral valve closing and opening. Average regional values of strain and MW indices were calculated by averaging the 4C, 3C, and 2C basal, mid, and apical segments, as based on the 18-segment model of the LV. Total MW per minute (MWI/min) was calculated by multiplying global MWI by the heart rate.

Results

LV ejection fraction and global longitudinal strain (GLS) were preserved and similar in all groups (GLS, controls vs. mild/moderate MR vs. severe MR vs. HTN: -21.28 ± 2.36 vs. -21.30 ± 1.49 vs. -20.93 ± 2.46 vs. -20.93 ± 2.46, p = 0.602). MR was classified as mild or moderate in 45% (n = 10) and severe in 55% (n = 12). A strong trend of higher global MWI (controls vs. mild/moderate MR vs. severe MR vs. HTN: 2098 ± 373 vs. 2036 ± 341 vs. 2237 ± 351 vs. 2297 ± 427 mmHg%, p = 0.171), as well as MWI/min could be noted in patients with hypertension and severe MR. Averaged regional deformation values showed a gradient increasing from base to apex in all groups, significantly more pronounced in the HTN patients. This deformation pattern was reflected in myocardial work distribution. In HTN, the basal region performed a lower percentage of total work, with the apex performing an increased workload. In the MR subgroups, the work was distributed similarly to the healthy controls Results are shown in Figure 1.

Conclusion

Non-invasive pressure strain relations offer additional information on cardiac function in HTN and MR with preserved LVEF and GLS. In HTN, MW is elevated and redistributed in the LV with an apex-to-base gradient signaling an apical compensation of basal impairment in the setting of increased afterload. Mild and moderate MR is associated with a compensated state of normal global MWI and work distribution, however, MWI/min in severe MR reveals an overall increase in workload - potentially predicting further LV remodeling in these patients over time.

Abstract 155 Figure 1

P3836Myocardial work distribution in hypertensive patients with basal septal hypertrophy - a non-invasive assessment with left ventricular pressure-strain relations

Background and aim

Localized basal septal hypertrophy (BSH) is a known marker of hypertension. However, the underlying functional significance of this morphologic finding is not clear. Non-invasive LV pressure estimates and speckle-tracking deformation curves can be used to quantify myocardial work (MW), which may offer insights into work distribution in increased afterload leading to better understanding of the early changes in hypertensive heart disease. The aim is to assess segmental strain and MW indices in hypertensive patients with and without BSH, as well as in healthy controls.

Methods

An echocardiogram was performed on a total of 149 patients with a diagnosis of long-standing hypertension and on 19 healthy age and sex-matched controls. The septum was measured at basal and mid-level in parasternal long-axis and four-chamber views. A two-part criterion - a positive visual assessment of an abrupt change in septal thickness seen in the 4C or PLAX view and a basal to mid-septal ratio ≥1.4 - was used to identify BSH. LV speckle-tracking was performed in 4C, 2C, and 3C views. Myocardial work index was calculated between mitral valve closing and opening. Average regional values of strain and MW indices were calculated by averaging the 4C, 3C, and 2C basal, mid, and apical segments.

Results

BSH was present in 19.2% (n=28) of the hypertensive cohort. There were no differences in LV ejection fraction or global longitudinal strain between the subgroups. The basal inferoseptum and anteroseptum were thicker in the hypertensive patients, significantly more so in the BSH subgroup, which was coupled with a proportional decrease in local deformation. Averaged regional deformation values showed a gradient increasing from base to apex in all subgroups, more pronounced in the BSH patients due to significantly impaired average basal deformation (controls vs. non-BSH vs. BSH: −18.33±1.92 vs. −17.24±2.14 vs. −15.56±2.08%, p<0.001). This deformation pattern was reflected in myocardial work distribution in hypertension, showing the basal region performing a lower percentage of global work, especially so in the BSH patients, while the apical region performed a significantly higher percentage, with a trend of further increase in the BSH subgroup (Figure 1).

Figure 1

Conclusion

Localised BSH, a structural finding in one-fifth of the hypertensive population, is related to functional impairment in regional systolic deformation and a pronounced redistribution of myocardial work during the cardiac cycle. An apex-to-base gradient in myocardial work signals an apical compensation of basal impairment in the setting of increased afterload. Clinical follow-up of patients is needed in order to assess the prognostic relevance of these findings.

Acknowledgement/Funding

Spanish Ministry of Economy and Competitiveness (TIN2014-52923-R), Fundacio La Maratό de TV3 (040310), H2020-MSCA-ITN-2016 (764738)

Severe combined immunodeficiency in Brazil: management, prognosis, and BCG-associated complications

BACKGROUND

Severe combined immunodeficiency (SCID) is one of the most severe forms of primary immunodeficiency. The objectives of this study were to analyze the diagnosis, treatment, and prognosis of SCID in Brazil and to document the impact of BCG vaccine.

METHODS

We actively searched for cases by contacting all Brazilian referral centers.

RESULTS

We contacted 23 centers and 70 patients from 65 families. Patients were born between 1996 and 2011, and 49 (70%) were male. More than half (39) of the diagnoses were made after 2006. Mean age at diagnosis declined from 9.7 to 6.1 months (P = .058) before and after 2000, respectively, and mean delay in diagnosis decreased from 7.9 to 4.2 months (P = .009). Most patients (60/70) were vaccinated with BCG before the diagnosis, 39 of 60 (65%) had complications related to BCG vaccine, and the complication was disseminated in 29 of 39 (74.3%). Less than half of the patients (30, 42.9%) underwent hematopoietic stem cell transplantation (HSCT). Half of the patients died (35, 50%), and 23 of these patients had not undergone HSCT. Disseminated BCG was the cause of death, either alone or in association with other causes, in 9 of 31 cases (29%, no data for 4 cases).

CONCLUSIONS

In Brazil, diagnosis of SCID has improved over the last decade, both in terms of the number of cases and age at diagnosis, although a much higher number of cases had been expected. Mortality is higher than in developed countries. Complications of BCG vaccine are an important warning sign for the presence of SCID and account for significant morbidity during disease progression.

[Endovascular treatment of aneurysms of the descending thoracic aorta--a new therapeutic perspective]

Endovascular treatment of aneurysmal disease of descending thoracic aorta and infra-renal abdominal aorta, has become an accepted technique, in selected cases due to the reduction of neurological morbidity, paraparesis or paraplegic and renal ischemia, associated with conventional surgery. The authors describe the first case performed in Portugal of a 75-year-old female with an expanding thoracic aneurysm managed by endovascular exclusion of the aneurysm with an EXCLUDER endoprosthesis, without any complications or evidence of endoleak, achieving complete exclusion of the aneurysm.

Mutations in the phosphorylase kinase gene PHKA2 are responsible for X-linked liver glycogen storage disease

Phosphorylase kinase (PHK) is a key enzyme in the control of glycogen breakdown. Several types of PHK deficiency have been described of which X-linked liver glycogenosis type I (XLG I) is the most common. Since the XLG I locus and the gene encoding the liver alpha-subunit gene of PHK (PHKA2) have both been localized to Xp22, PHKA2 was a candidate gene for XLG I. In this study we identified four point mutations in four unrelated XLG I patients: three mutations introduce a premature stop codon, whereas the fourth mutation abolishes a splice site consensus sequence leading to exon skipping. These findings indicate that PHKA2 is the XLG I gene.

[Prevalence of extracranial carotid occlusive disease. Non-invasive study]

Cerebrovascular disease is the most important cause of mortality and morbility in some European Countries, but the prevalence of carotid occlusive disease has not been adequately assessed. From 1985 to 1987, 1,143 patients were consecutively evaluated in the Vascular Laboratory in order to determine the presence of extracranial carotid occlusive disease. 638 (55.8%) were males and 505 (44.2%) females and mean age was 58 years (16-87). 509 had previously focal brain ischemia, ocular and/or hemispheric (Group I), 78 had assymptomatic cervical bruit (Group II), 55 non-hemispheric neurologic dysfunction (Group III) and 501 had atypical symptoms for cerebrovascular disease (Group IV). Diagnostic criteria for carotid disease: were peak frequency greater than 4.0 KHz; spectral broadening greater than 40% and late sysstolic turbulence. Global prevalence of carotid disease was 31.8% and the results in each group were: Gr. I-37.2%; Gr. II-57.7%; Gr. III-43.6%; Gr. IV-21.2%. 49% of the patients had hypertension, 22.8% dyslipidemia, 22.4% evidence of coronary disease and 13.6% had diabetes. Hypertension, diabetes, coronary disease and the coexistence of two risk factors were significantly more prevalent in the group of patients with carotid disease. These results confirm a high prevalence of carotid disease in this population, which is comparable to the one is northern european populations.

Trypanosoma cruzi: the fate of bloodstream trypomastigote, amastigote, metacyclic trypomastigote and epimastigote forms in the peritoneal macrophages of immune and non-immune mice in vivo

Experiments were done in vivo in order to compare the ability of Trypanosoma cruzi bloodstream trypomastigotes (BTr), amastigotes (Am), metacyclic trypomastigotes (MTr) and epimastigotes (Ep) to proliferate in the peritoneal macrophages of the following groups of A/Sn mice: actively immunized with increasing doses of living BTr (AIM); mice passively immunized with homologous immune serum (ISTM); mice passively transfused with normal homologous serum (NSTM) and normal mice (NM). Parasite load was evaluated by counting the number of infected peritoneal macrophages harvested on the 4th day after i.p. challenge with one of the forms. All four parasite stages infected NM. AIM seldom showed parasitized macrophages after challenge with any of the forms. ISTM always harboured numerous parasitized macrophages. The only form susceptible to humoral immunity was the Am.

Ambulatory calf volume plethysmography in the assessment of venous insufficiency

Ambulatory calf volume plethysmography has been used to study venous insufficiency in 50 lower limbs. The results demonstrate that it is possible to determine the presence of venous insufficiency and differentiate between normal limbs, limbs with superficial venous insufficiency only, limbs with deep venous insufficiency and limbs with deep venous insufficiency and occlusion by determining the ambulatory volume change and maximum venous outflow or venous volume.