A benchmark for Monte Carlo simulations in gamma-ray spectrometry Part II: True coincidence summing correction factors

The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides. The exercise input files and calculation results with practical recommendations are made available for new users on a dedicated webpage.

Selection, characterization and in vivo evaluation of novel CD44v6-targeting antibodies for targeted molecular radiotherapy

Molecular radiotherapy combines the advantages of systemic administration of highly specific antibodies or peptides and the localized potency of ionizing radiation. A potential target for molecular radiotherapy is the cell surface antigen CD44v6, which is overexpressed in numerous cancers, with limited expression in normal tissues. The aim of the present study was to generate and characterize a panel of human anti-CD44v6 antibodies and identify a suitable candidate for future use in molecular radiotherapy of CD44v6-expressing cancers. Binders were first isolated from large synthetic phage display libraries containing human scFv and Fab antibody fragments. The antibodies were extensively analyzed through in vitro investigations of binding kinetics, affinity, off-target binding, and cell binding. Lead candidates were further subjected to in vivo biodistribution studies in mice bearing anaplastic thyroid cancer xenografts that express high levels of CD44v6. Additionally, antigen-dependent tumor uptake of the lead candidate was verified in additional xenograft models with varying levels of target expression. Interestingly, although only small differences were observed among the top antibody candidates in vitro, significant differences in tumor uptake and retention were uncovered in in vivo experiments. A high-affinity anti-CD44v6 lead drug candidate was identified, mAb UU-40, which exhibited favorable target binding properties and in vivo distribution. In conclusion, a panel of human anti-CD44v6 antibodies was successfully generated and characterized in this study. Through comprehensive evaluation, mAb UU-40 was identified as a promising lead candidate for future molecular radiotherapy of CD44v6-expressing cancers due to its high affinity, excellent target binding properties, and desirable in vivo distribution characteristics.

Relationship between iron deficiency and expression of genes involved in iron metabolism in human myocardium and skeletal muscle

BACKGROUND

Iron deficiency (ID) is associated with adverse prognosis in patients with heart failure. This study aims to investigate the relationship between ID and expression of genes involved in iron metabolism in human myocardium and skeletal muscle, focusing on Transferrin 1 receptor (TfR1), the main pathway of cellular iron uptake.

METHODS

Patients undergoing elective CABG were assessed prior to surgery with echocardiography and serum iron parameters. Core needle biopsies were collected from the left and right ventricle (LV, RV), the right atrium and intercostal skeletal muscle (SM). Gene expression analyses were done by mRNA sequencing.

RESULTS

Of 69 patients (median age 69 years, 91% men), 28% had ID. 26% had HFrEF, 25% had HFpEF physiology according to echocardiographic findings and NT-proBNP levels, and 49% had normal LV function. The expression of TfR1 was increased in patients with ID compared to patients without ID in ventricular tissue (p = 0.04) and in intercostal SM (p = 0.01). The increase in TfR1 expression in LV and RV was more pronounced when analysing patients with absolute ID (S-Ferritin<100 μg/L). Analysing the correlation between various iron parameters, S-Ferritin levels showed the strongest correlation with TfR1 expression. There was no correlation with NT-proBNP levels and no difference in TfR1 expression between different HF phenotypes.

CONCLUSIONS

In patients undergoing elective CABG we found an association between ID and increased TfR1 expression in myocardium regardless of LV function, indicating physiologically upregulated TfR1 expression in the presence of ID to restore intracellular iron needs.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.govNCT03671122.

POS0053 ABUNDANT AUTOANTIBODY ISOTYPES IN IDIOPATHIC INFLAMMATORY MYOPATHIES

Background

Anti-synthetase syndrome (ASSD), a sub-group of idiopathic inflammatory myopathies (IIM) is characterized by the presence of autoantibodies targeting aminoacyl tRNA synthetases (aaRS) and specific clinical manifestations such as myositis and interstitial lung disease (ILD) [1]. Some of the most common anti-aaRS autoantibodies in ASSD are anti-Jo1, -PL7, -PL12 and-EJ. In addition, many anti-aaRS positive patients are also positive for anti-Ro52. Having the combination of anti-Jo1 and anti-Ro52 increases the risk of developing ILD [2]. The presence of autoantibodies is an important part of the classification of ASSD, however only autoantibodies of IgG isotype are usually analyzed in the clinical setting. In rheumatoid arthritis there is evidence that anti-citrullinated protein/peptide antibodies (ACPA) can be found as IgG, IgA and IgM, and importantly, specific isotypes might correlate with disease activity [3, 4].

Objectives

To verify if other autoantibody isotypes, besides IgG, might be present in sera of patients with IIM/ASSD and to compare with the corresponding frequencies in population controls (PC).

Methods

Stored sera collected from consecutive 366 IIM patients and 156 age/gender matched PC at Karolinska University Hospital were retrospectively selected. The serum samples were screened for the presence of autoantibodies of isotypes IgG, IgA and IgM, against a panel of 20 antigens representing Jo1 (HisRS), PL7 (ThrRS), PL12 (AlaRS), EJ (GlyRS), and Ro52 (TRIM21) using a multiplex bead array assay.

Results

We identified IIM patients with autoantibodies of different isotypes, and a low frequency in PC (Figure 1). For anti-Jo1 autoantibodies we could detect IIM patients with only IgG (n=13), only IgM (n=8) and only IgA (n=4), but the majority had a combination of two (n=32) or three isotypes (n=16). For the other anti-aaRS autoantibodies the distribution was more equal to each of the three isotypes with anti-PL12 and anti-PL7 being represented by a slightly higher frequency of IgG and only a few patients had antibodies of more than one isotype targeting PL12, PL7 or EJ. The majority of anti-Ro52 positive IIM patients (n=52) only harbored IgG isotype. The combination of anti-Ro52 and anti-aaRS autoantibodies was identified in 28 patients (anti-Jo1 (n=19), -PL12 (n=2), -PL7 (n=3), and -EJ (n=4)). Most patients with such combination had anti-Ro52 IgG together with anti-aaRS IgG or IgG in combination with IgA and/or IgM. The exception was observed for three anti-Jo1 positive patients who had the combination anti-Ro52 IgG with only anti-Jo1 IgM and one anti-PL7 positive patient who had anti-Ro52 IgA together with anti-PL7 IgA and IgG.

Figure 1.

Venn diagrams showing reactivity in idiopathic inflammatory myopathies (IIM) (top) and population controls (PC) (bottom) for the three autoantibody isotypes IgG, IgA and IgM against five myositis antigens: Jo1 (HisRS), PL12 (AlaRS), ThrRS (PL7), EJ (GlyRS) and Ro52 (TRIM21).

Conclusion

The frequency of the different autoantibody isotypes seems to be autoantigen dependent. Our results suggest that for anti-aaRS autoantibodies it could be important to investigate additional autoantibody isotypes, as some patients only harbor autoantibodies of IgM or IgA isotypes but not IgG. The clinical relevance of the different antibody isotypes still needs to be determined.

References

[1]Mahler, M., et al., Rev, 2014. 13(4-5): p. 367-71.

[2]Huang, H.L., et al., J Clin Neurosci, 2020.

[3]Arlestig, L., et al., Ann Rheum Dis, 2012. 71(6): p. 825-9.

[4]Roos Ljungberg, K., et al., Arthritis Res Ther, 2020. 22(1): p. 274.

Table 1.

Total number of individuals and percentage (n (%)) in each group for each of the isotypes and antigens.

anti-Jo1anti-PL12anti-PL7anti-EJanti-Ro52IIMPCIIMPCIIMPCIIMPCIIMPCIgG61 (16.7)1 (0.6)7 (1.9)0 (0.0)7 (1.9)0 (0.0)3 (0.8)0 (0.0)54 (14.8)5 (3.2)IgA20 (5.5)0 (0.0)2 (1.2)1 (0.6)3 (0.8)2 (1.3)1 (0.3)1 (0.6)3 (0.8)1 (0.6)IgM56 (15.3)1 (0.6)1 (0.3)2 (1.3)7 (1.9)0 (0.0)1 (0.3)0 (0.0)3 (0.8)2 (1.3)

Acknowledgements

SciLifeLab facilities Autoimmunity and Serology Profiling and Human Antibody Therapeutics (Drug Discovery and Development). IMI project EUbOPEN, This project has received funding from the Innovative Medicines Initiative 2 Joint Undertaking (JU) under grant agreement No 875510. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and EFPIA and Ontario Institute for Cancer Research, Royal Institution for the Advancement of Learning McGill University, Kungliga Tekniska Hoegskolan, Diamond Light Source Limited.

Disclosure of Interests

Charlotta Preger Grant/research support from: IMI project EUbOPEN, Grant no 875510, Antonella Notarnicola: None declared, Cecilia Hellström: None declared, Edvard Wigren Grant/research support from: IMI project EUbOPEN, Grant no 875510, Ingrid E. Lundberg Shareholder of: Roche and Novartis, Consultant of: Corbus Pharmaceuticals Inc, Astra Zeneca, Bristol Myer´s Squibb, Corbus Pharmaceutical, EMD Serono Research & Development Institute, Argenx, Octapharma, Kezaar, Orphazyme, and Janssen, Grant/research support from: Astra Zeneca, Per-Johan Jakobsson Shareholder of: Gesynta Pharma, Consultant of: UCB, Grant/research support from: Gesynta Pharma, Helena Persson Employee of: Affibody AB, Susanne Gräslund Grant/research support from: IMI project EUbOPEN, Grant no 875510

POS0434 A NOVEL TARGET FOR TREATMENT OF INFLAMMATORY JOINT DISEASES

Background

A significant number of patients with inflammatory joint disorders do not respond or experience a waning effect to currently available pharmaceuticals, which emphasizes a high medical need for new efficacious drugs operating through novel targets and modes of action. One unexplored novel target is Bile Salt-Stimulated Lipase (BSSL).

We have shown that patients with rheumatoid arthritis (RA), psoriasis arthritis (PsA), and juvenile idiopathic arthritis (JIA) have increased BSSL plasma levels compared to healthy controls, and that these levels correlate with disease activity scores. Moreover, conventional BSSL knockout mice are protected from developing disease in several recognized in vivo arthritis models and antibodies targeting BSSL prevent or mitigate arthritis in rodent models1.

We have further shown that BSSL is secreted from activated granulocytes, binds to monocytes and stimulates their migration in vitro. With that knowledge, we developed a humanized anti-BSSL antibody (SOL-116) that blocks BSSL from binding to monocytes and we are now evaluating SOL-116 as candidate drug for treatment of chronic inflammatory joint diseases, including RA, PsA and JIA in man.

Objectives

The aim of the present study was to characterize SOL-116’s biological activity in vitro and verify the therapeutic efficacy in the pristane induced arthritis (PIA) rat model.

Methods

The affinity of SOL-116 to human, mouse and rat BSSL was measured by surface plasmon resonance biosensor technology. The epitope on human BSSL was mapped by hydrogen deuterium exchange mass spectrometry (HDX-MS) and confirmed by crystallization of SOL-116 Fab-fragments with human BSSL. For efficacy evaluation, arthritis was induced in DA rats by administration of pristane. SOL-116 at three different doses (10, 30 and 90 mg/kg) or vehicle control were administered subcutaneously on day 5, 10 and 15 after disease induction. Disease activity was evaluated daily from day 7 in a blinded fashion using a macroscopic scoring system of the four limbs. To gain knowledge about the mechanism of action, the effect of SOL-116 on BSSL induced cell migration was evaluated using a transwell migration assay.

Results

SOL-116 binds to human, mouse, and rat BSSL, although a single amino acid deviation in the BSSL epitope results in approximately 80-fold lower affinity to rodent compared to human BSSL protein. In the efficacy validation study, treatment with highest dose SOL-116 (90 mg/kg) significantly mitigated disease severity in the PIA rats (Figure 1A). The relatively high doses of SOL-116 were chosen to compensate the low affinity for rat BSSL. A decrease in disease severity was also seen with SOL-116 at 30 mg/kg and 10 mg/kg, indicating a dose response, albeit not statistically significant. The plasma concentration of SOL-116 at day 19 correlated significantly to the arthritis score (Figure 1B). Mechanistic studies show that BSSL stimulates migration of CD14+ monocytes, and that SOL-116 prevents this effect in a dose dependent manner.

Figure 1.

Arthritis development and SOL-116 exposure in rats following pristane injection. (A) Animals treated with SOL-116 (90 mg/kg) show significantly lower disease severity compared to vehicle treated animals. Results are presented as mean ± SEM. (B) Plasma concentration of SOL-116 at day 19 in animals treated with 90 mg/kg correlates to disease severity.

Conclusion

The present study verifies that BSSL plays an important role in inflammation and that SOL-116 is a promising biologic drug candidate for novel treatment of chronic inflammatory joint diseases.

References

[1]Lindquist S, Andersson EL, Lundberg L, Hernell O. Bile salt-stimulated lipase plays an unexpected role in arthritis development in rodents. PLoS One. 2012;7(10):e47006.

Acknowledgements

The authors are grateful to Mrs. Eva-Lotta Andersson for excellent technical assistance.

Disclosure of Interests

Susanne Lindquist Shareholder of: Lipum AB, Umeå, Sweden, Grant/research support from: Lipum AB, Employee of: Lipum AB, Helena Persson: None declared, Annette Roos: None declared, Lennart Lundberg Shareholder of: Lipum AB, Consultant of: Lipum AB, Grant/research support from: Lipum AB, Employee of: Lipum AB, Olle Hernell Shareholder of: Lipum AB, Consultant of: Lipum AB, Grant/research support from: Lipum AB, Employee of: Lipum AB.

SAT0288 CHARACTERIZATION OF ANTI-AMINOACYL TRNA SYNTHETASE AUTOANTIBODIES IN PATIENTS WITH IDIOPATHIC INFLAMMATORY MYOPATHIES

Background:

Idiopathic inflammatory myopathies (IIM) are rare chronic inflammatory diseases associated with high mortality and morbidity [1]. One sub-group of IIM, anti-synthetase syndrome (ASS), is characterized by the presence of autoantibodies that target aminoacyl transfer(t) RNA synthetases (aaRS), together with specific clinical manifestations such as myositis, interstitial lung disease (ILD), arthritis, mechanic’s hand, Raynaud’s syndrome and fever [2]. The most common anti-aaRS autoantibody, anti-Jo1 targeting histidyl tRNA synthetase (HisRS), is present in up to 20-30% of patients with IIM, and up to 90% of patients with myositis and ILD [3, 4]. Besides Jo1, there are today seven other identified autoantigens within the aaRS family.

Objectives:

A large part of patients with IIM, including individuals with clinical manifestations indicating ASS, test seronegative to all known myositis specific autoantibodies. However, these patients could potentially harbor autoantibodies against targets not tested for in clinic. In this study, we aimed at extending the detection of autoantibodies by including all cytoplasmic aaRS in the analysis of patients with IIM. We hypothesized the existence of new potential autoantigens within this protein family.

Methods:

The presence of anti-aaRS autoantibodies was determined using a multiplex suspension bead array assay on 242 IIM patients from the Karolinska University Hospital myositis cohort. A panel of 186 recombinant constructs, representing 57 proteins that included full-length or partial sequence overlaps between constructs of all cytoplasmic aaRS as well as other myositis related proteins, were coupled to magnetic color-coded beads and each plasma sample was tested against the complete antigen panel.

Results:

By the use of this multiplex method we identified patients with autoantibodies against many of the tested aaRS. Autoantibodies binding to HisRS have previously been shown to bind with higher reactivity to the WHEP domain of HisRS and this was also confirmed in this study. We confirmed reactivity against three of the other aaRS tested for in the clinic (PL-12, PL-7, and EJ). In addition, we identified patients positive for anti-Zo, -KS and -HA, autoantibodies usually not screened for in routine. Finally, our data indicates that there are autoantibodies binding to other aaRS than the previously known eight autoantigens, which will be presented.

Conclusion:

In this study, we could detect autoantibodies in plasma from patients with IIM, both against the most common aaRS autoantigens, but also against other aaRS that are usually not tested for in clinic. We conclude that it is important to continue the studies of anti-aaRS autoantibodies, and their correlation to clinical manifestations, and in the long run also include more aaRS autoantigens in clinical practice.

References:

[1]Dobloug, G.C., et al., Mortality in idiopathic inflammatory myopathy: results from a Swedish nationwide population-based cohort study. Ann Rheum Dis, 2018. 77(1): p. 40-47.

[2]Barsotti, S. and I.E. Lundberg, Myositis an evolving spectrum of disease. Immunol Med, 2018. 41(2): p. 46-54.

[3]Vencovsky, J., H. Alexanderson, and I.E. Lundberg, Idiopathic Inflammatory Myopathies. Rheum Dis Clin North Am, 2019. 45(4): p. 569-581.

[4]Richards, T.J., et al., Characterization and peripheral blood biomarker assessment of anti-Jo-1 antibody-positive interstitial lung disease. Arthritis Rheum, 2009. 60(7): p. 2183-92.

Disclosure of Interests:

Charlotta Preger: None declared, Antonella Notarnicola: None declared, Cecilia Hellström: None declared, Edvard Wigren: None declared, Catia Cerqueira: None declared, Peter Nilsson: None declared, Ingrid E. Lundberg Grant/research support from: Bristol Meyer Squibb, Corbus Pharmaceuticals, Inc and Astra Zeneca, Helena Persson: None declared, Susanne Gräslund: None declared, Per-Johan Jakobsson Shareholder of: Gesynta Pharma, Grant/research support from: Gesynta Pharma, AstraZeneca,

SAT0335 SERUM AND BALF-DERIVED ANTI-JO1 AUTOANTIBODIES EXHIBIT HIGH REACTIVITY TO DISTINCT HISRS DOMAINS AND ASSOCIATE WITH LUNG AND JOINT INVOLVEMENT IN PATIENTS WITH IIM/ASS

Background:

Autoantibodies that target aminoacyl transfer(t) RNA synthetases (aaRS) represent the serological marker of the anti-synthetase syndrome (ASS), a major subgroup of the idiopathic inflammatory myopathies (IIM) (1). Among the anti-aaRS, anti-histidyl tRNA synthetase (HisRS) autoantibodies (anti-Jo1) are the most common. Up to 90% of IIM/ASS patients diagnosed with interstitial lung disease (ILD) harbor anti-Jo1 autoantibodies (2).

Objectives:

Reactivity and affinity of anti-Jo1 autoantibodies from serum and broncheoalveolar lavage fluid (BALF) were investigated against HisRS autoantigen. Associations with clinical data from patients IIM/ASS were addressed.

Methods:

Total IgGs were purified by affinity chromatography. Samples and clinical data were obtained from: i) 26 anti-Jo1+patients (19 at diagnosis, 16/19 at follow-up, 7 BALF/matching serum at baseline; ii) 29 anti-Jo1-(25 serum at diagnosis, 4 BALF/matching serum at baseline); iii) 24 age/gender matched healthy controls. Anti-Jo1 IgG and IgA response against HisRS was evaluated by ELISA and western blot. Affinity was measured by surface plasmon resonance. HisRS full-length (HisRS-FL), two HisRS domains (ABD and CD), and two HisRS splice variants (WHEP and WHEP + ABD splice variant (SV)) were tested. Correlations between autoantibody reactivity and clinical data, at baseline and over disease course, were evaluated.

Results:

Anti-Jo1 autoantibodies from serum and lung bound HisRS-FL, WHEP and SV with high reactivity and affinity already at diagnosis and recognized both conformational and linear HisRS epitopes (Fig. 1). Levels of autoantibodies (against HisRS-FL, -domains and -splice variants) varied among patients and overtime. Patients with ILD, arthritis and less skin involvement presented higher anti-Jo1 titers compared to those with lower anti-Jo1 titers and to the anti-Jo1 negative group (Fig. 2). Anti-WHEP reactivity in BALF strongly correlated with poor pulmonary function.

Conclusion:

High reactivity and affinity at time of diagnosis indicates that autoimmunity against HisRS is most likely initiated before IIM/ASS diagnosis. Reactivity to specific splice variants of HisRS may be employed as diagnostic and prognostic markers.

References:

[1]Marguerie C, Bunn CC, Beynon HL, Bernstein RM, Hughes JM, So AK, Walport MJ: Polymyositis, pulmonary fibrosis and autoantibodies to aminoacyl-tRNA synthetase enzymes. Q J Med 1990, 77(282):1019-1038

[2]Richards TJ, Eggebeen A, Gibson K, Yousem S, Fuhrman C, Gochuico BR, Fertig N, Oddis CV, Kaminski N, Rosas IO et al: Characterization and peripheral blood biomarker assessment of anti-Jo-1 antibody-positive interstitial lung disease. Arthritis Rheum 2009, 60(7):2183-2192.

Fig. 1.

Anti-Jo1 reactivity in total IgG purified from the first available serum sample

Fig. 2.

Reactivity of total anti-Jo1+ IgG purified from the first available serum close to IIM/ASS diagnosis in relation to clinical data

Disclosure of Interests:

Antonella Notarnicola: None declared, Charlotta Preger: None declared, Susanna Lundström: None declared, Nuria Renard: None declared, Edvard Wigren: None declared, Eveline Van Gompel: None declared, Angeles Shunashy Galindo-Feria: None declared, Helena Persson: None declared, Maryam Fathi: None declared, Johan Grunewald: None declared, Per-Johan Jakobsson Shareholder of: Gesynta Pharma, Grant/research support from: Gesynta Pharma, AstraZeneca,, Susanne Gräslund: None declared, Ingrid E. Lundberg Grant/research support from: Bristol Meyer Squibb, Corbus Pharmaceuticals, Inc and Astra Zeneca, Catia Cerqueira: None declared

P2790Novel endomyocardial micro-biopsy device for higher precision and reduced complication risks

Introduction

Endomyocardial biopsy (EMB) is the gold standard for diagnosis of several cardiac diseases, yet its use is limited by low diagnostic yield and significant complication risks. The size of the current devices allows only limited steering to different parts of the ventricle walls. In transplant monitoring, repeated biopsies with the current devices can cause scarring that makes it increasingly difficult to obtain adequate samples. We hypothesised that several of the shortcomings of EMB can be avoided with a smaller and more steerable device. Further, we hypothesised that the novel sampling procedure could be coupled to a low-input molecular analysis method, such as RNA-sequencing (RNA-seq), to provide molecular characterisation of the tissue without the need of large biopsy samples.

Purpose

To develop an EMB device with significantly smaller dimensions, for future use in diagnostics and research investigations. Specific aims were to test feasibility and safety of the procedure, as well as the quality of the generated molecular data.

Methods

65 “micro biopsy” (micro-EMB) device prototypes were designed and evaluated in-house. The prototypes were evaluated either in an ex-vivo simulator or in acute non-survival pig experiments (n=23). Once the final device design was reached, an in vivo trial was set up using six naive Yorkshire farm pigs. Micro-EMB, conventional EMB, skeletal muscle and blood samples were collected for RNA-seq characterisation and comparison. In half of the animals (n=3), micro-EMB was the only intervention in order to prioritise safety evaluations. The animals were monitored for one week.

Results

The final device design has an outer diameter (OD) of 0.4 mm, compared to a conventional 11 mm device (in the opened position), Fig 1A. The device can be directed to different parts of the myocardium in both ventricles. In the in vivo evaluation in swine, 81% of the biopsy attempts (n=157) were successful. High quality RNA-seq data was generated from 91% of the sequenced heart micro-biopsy samples (n=32). The gene expression signatures of samples taken with the novel device were comparable with samples taken with a conventional device, Fig 1B. No major complications were detected either during periprocedural monitoring or during the follow-up. The tissue mark after micro-biopsy was markedly smaller than after conventional endomyocardial biopsy.

A) Bioptome dimensions. B) RNA-seq data.

Conclusions

Our preliminary data suggest that the novel submillimeter biopsy device, coupled with RNA-seq, provides a feasible method to obtain molecular data from the myocardium. The method is less traumatic and has a higher flexibility compared to conventional methods, enabling safer and more specific sampling from different parts of the myocardium. In the long term, the procedure could open unprecedented diagnostic and research possibilities. Future studies should be directed to establish the capabilities of the novel method in a relevant disease model.

Acknowledgement/Funding

Family Erling Persson Foundation. The Söderberg foundations. KID (Karolinska Institutet). The 4D project. Stockholm county council. Astra Zeneca.

217Metabolomic profile of patients with new onset heart failure; more microvascular dysfunction in patients with preserved ejection fraction compared to reduced ejection fraction - the PREFERS Study

Background

Heart failure with preserved (HFpEF) and reduced (HFrEF) ejection fraction are both associated with metabolic derangements which may have different pathophysiological implications

Purpose

To identify metabolites and pathways differentially altered with the potential to differentiate HFpEF from HFrEF.

Methods

In the PREFERS Stockholm study (Preserved and Reduced Ejection Fraction Epidemiological Regional Study) 121 endogenous plasma metabolites were assessed by targeted mass spectrometry. Partial Least Squares Discriminant Analysis (PLS-DA) was used to identify metabolites differentially altered in new onset HF divided into HFpEF (EF ≥50%, n=46) versus HFrEF (ÈF<40%, n=75) patients. Multivariable logistic regression was used to assess independent associations between HF group and selected metabolites, including sex, age and eGFR as co-variates.

Results

Compared to HFrEF, HFpEF patients were older; 77 vs 65 years (p<0.001), more often female 54% vs 46% (p=0.004) with hypertension 60% vs 40% (p<0.001) and diabetes 63% vs 37% (p=0.007), and lower NT-proBNP 720 vs 1295 ng/L (p=0.014) and eGFR 63 vs 72 mL/min/1.73 m2 (p<0.001).

HFpEF patients had higher levels of hydroxyproline, cysteine, symmetric dimethyl arginine, alanine, kynurenine and acylcarinitines and lower levels of cAMP, lysoPC, L-carnitine, arginine, cGMP, serine and lactate (Figure). HFpEF was independently associated with reduced levels of cGMP (OR 0.98 [95% CI: 0.97–0.99; p=0.008]), serine (0.97 [0.95–1.00; 0.047]) and cAMP (0.97 [0.94–0.99; 0.009]).

Figure 1

Conclusions

In new onset HF patients, HFpEF was associated with decreased cGMP, cAMP and serine indicating increased oxidative stress, impaired innate immune function and myocardial hypertrophy. HFpEF patients displayed a distinct metabolic profile reflecting increased endothelial dysfunction, hypoxia, inflammation and myocardial fibrosis pointing towards more involvement of microvascular dysfunction compared to HFrEF.

Acknowledgement/Funding

Science for Life Laboratory–Astra Zeneca; Mölndal, Sweden collaborative grant No. 1377

P6334Daily body weight in patients with chronic heart failure: improved diagnostic value by analysing prolonged time intervals

Background

Daily body weight (BW) is a mainstay in the management of patients with chronic heart failure (HF). Guidelines recommend to take action if BW increases more than 2kg within 3 days. However, the evidence behind the 2kg/3d rule is unclear and studies have shown poor diagnostic performance of this algorithm.

Purpose

To assess the diagnostic value of different BW thresholds and time intervals to alert for imminent HF decompensation.

Methods

We studied 184 patients with HF (age 71±10 yr, EF 26±11%). 43% had been hospitalized for HF during the preceding year. They were assessed by daily BW using digital scales with direct data transfer to a central data base. The mean follow-up was 286 days.

To decrease day-to-day variability, BW was analysed based on a daily moving average over 3 days. We retrospectively calculated the sensitivity and false-positive rate of BW thresholds at 1.5, 2.0, 2.5, 3.0 and 3.5 kg and time intervals between 2 and 30 days. Threshold crossings occurring within 30 days prior to a hospitalization for decompensated HF were deemed a positive alert.

Results

The sensitivity of 2kg/3d was poor (13%). Prolonging the time interval of weight changes markedly improved sensitivity. Increasing the weight threshold decreased the false positive rate. Greatest sensitivity (60%) was achieved using a 14 day interval at a weight threshold of 1.5 kg. However, this was associated with a high rate of false alerts (3.1 per patient/year). A weight threshold of 3.5 kg resulted in excellent specificity (0.3 false alerts per patient/year), however sensitivity was low (20%, 20 day time interval).

Conclusion

Monitoring daily BW using a 2kg/3d algorithm is associated with poor diagnostic performance. Generally, by analyzing stable trends over time (moving average) and using prolonged time intervals, BW monitoring with digital scales can achieve a clinically meaningful diagnostic performance. This new approach to BW monitoring may improve early detection of imminent HF decompensation.

P764A quality improvement program for heart failure involving structured patient data, diagnosis and organization of care - results from the 4D heart failure project

Background

Heart failure (HF) management is suboptimal in Sweden despite available evidence-based treatments.

Purpose

We hypothesized that a comprehensive organizational improvement programme could improve HF management, treatment and outcome.

Methods

Between 2012 and 2017 a HF improvement programme (the 4D Heart Failure project) was conducted in an urban region in Sweden (>2.2 million inhabitants). The steering committee led working groups 2012–17 including all health care providers with 250 primary care centers to build a standardized care process. HF outpatient care was centralized at five hospital-based HF clinics and included multidisciplinary health care teams.

The outcomes were: 1) prescription withdrawals of HF medication (RAS-inhibitors and beta-blockers, MRA) per year, expressed as percentage (%), 2) one-year all-cause mortality or heart failure readmission by multivariable Cox regression, 3) total number of admitted HF patients, subdivided by new-onset and previously known HF, per million inhabitants and year.

Results

Between 2012 and 2017, yearly visits to the five HF clinics increased 3.5 times from 3200 to 11700, to a total of 47400 visits or 15800 patients (average 3 visits/patient). Prescription withdrawals of MRAs for readmitted HF patients increased from 37% to 60%, of beta-blockers and RAS-inhibitors from 80 to 90%. Similar increases were noted for all admitted patients. One-year mortality or HF readmission was 48% (n=17124/35880) over the period and decreased significantly (adjusted HR 0.98 per year, 95% CI 0.97–0.99, p<0.001). Number of admitted HF patients, new-onset or readmitted HF patients decreased by 16%, 13% and 20%, respectively (p<0.0001, Figure).

Numbers of admitted patients 2012-2017

Conclusion

A comprehensive standardized care HF management programme in an urban region substantially increased access to multidisciplinary hospital-based HF clinics, and increased use of evidence-based medications. HF admissions and readmissions were reduced, as was the risk of one-year mortality or HF rehospitalization.

Acknowledgement/Funding

County of Stockholm and the Karolinska Institute

In situ Studies and Simulations of Mould Filling with a Model System for PIM

The processing conditions and the mould design are important parts of the powder injection moulding (PIM) process. In the present work, the mould filling phase of the process has been studied in situ with a special mould equipped with a sight glass using a high speed camera. Effects of features such as the mould temperature, the melt temperature, the surface roughness of the mould cavity, the gate dimensions, the mould design and the flow rate on the filling behaviour were demonstrated. In particular it was noted that a rougher mould surface to some extent facilitated the filling of the mould. The mould temperature, the nominal melt temperature and the flow rate affected the position of weld lines via the cooling of the feedstock and the corresponding change of the melt viscosity. The experimentally determined weld-line positions were compared with predictions from numerical simulations performed with the commercial software Moldex3D. The agreement between the experiment and the prediction was in most cases quite fair or good. The in situ observation of the mould filling also provided the possibility to study how the gate dimensions and the flow rate influenced the jetting behaviour.

Rheological and Thermal Properties of a Model System for PIM

Powder injection moulding (PIM) is an important and accepted industrial technique for net shaping of precision components which can have a rather complex geometry. In order to meet the imposed, often rather strict, requirements with regard to dimensional accuracy, it is important to have an adequate knowledge and control of the rheological behaviour and the related processing properties of the powder/polymer melt (feedstock). Such a knowledge is furthermore of crucial importance in numerical simulations of the PIM-process. In the present work, a model system, consisting of steel powder, poly(ethylene glycol) and wax, is used in order to illustrate how the viscometric properties as well as thermal properties, such as the conductivity and the specific heat, of the system can be related to the corresponding properties of the polymeric binder system. In a similar way, the pvT (pressure-volume-temperature)-behaviour of the model system is analysed and discussed. The pvT-behaviour, which has not been extensively reported on for PIM-feedstocks, is considered to be of significant relevance for controlling the outcome of the injection moulding process.

A study of 136 cases of adder bite treated in Swedish hospitals during one year

The adder (Vipera verus) is the only naturally occurring poisonous snake in Sweden. During one year, 136 patients were hospitalized due to adder bites in a population of 5.3 mill. (63% of the total population). These patients could be traced through the central register on diagnosis codes and have been studied retrospectively. The main purpose of the investigation was to study the epidemiology and to estimate the degree of poisoning, thereby getting an idea of the frequency of really severe cases. Minor local symptoms occurred in 27% of the patients, whereas 46% suffered mild, 15% moderate and 12% severe poisonings. The average duration of hospitalization was 1.6, 3.8, 5.5 and 7.6 days, respectively, for these four groups. Shock, CNS disturbances, anaphylactic reactions, extensive edemas, renal dysfunction and severe anemia were typical findings in the group with severe reactions. Although no deaths occurred, the proportion of severe cases contrasts with the current conception that severe envenomation after adder bites is rare. The mortality due to adder bite has been low during the last decades. Earlier the situation was different, and during 1911-78 altogether 44 deaths due to adder bite were registered in Sweden.

No apparent effect of surgery for temporal lobe epilepsy on heart rate variability

BACKGROUND

Impaired cardiac autonomic function may contribute to the risk of sudden unexpected death in epilepsy (SUDEP). Clinical observations indicate that successful epilepsy surgery is associated with a reduced risk of SUDEP. However, in a previous study we found impaired cardiac control pre-surgically in patients with poor outcome of surgery, indicating an a priori lower risk in responders to epilepsy surgery. We have now examined the effect of surgery on cardiac autonomic control in the same patients.

METHODS

We used 24 h EKG recordings to assess heart rate variability (HRV) by spectral analysis in 21 consecutive patients after temporal lobe epilepsy surgery. The HRV was compared with healthy controls, with pre-surgical HRV in the same patients, and analyzed in relation to seizure control 1 year after surgery.

RESULTS

The patients with poor outcome after surgery had significantly lower SD of RR-intervals, total power, very low frequency power and low frequency power than matched healthy controls. The patients with favorable outcome did not differ from the controls, and the postoperative HRV was not different from HRV before surgery in any of the patient groups.

CONCLUSION

We could not demonstrate any effect on HRV of temporal lobe epilepsy surgery in these patients. The observed lower HRV in the poor outcome group was present already before epilepsy surgery as previously reported. Although our results need confirmation in a larger study, the observations suggest that the increased risk of SUDEP in patients failing epilepsy surgery may be due to a common factor predisposing to surgical failure, impaired HRV as well as to an increased risk of SUDEP.

Predicting readmissions and cardiovascular events in heart failure patients

AIMS

To analyse measures of clinical data, functional capacity, left ventricular function and neurohormonal activation for the ability to predict mortality and morbidity in patients after a hospitalisation for heart failure.

METHODS

In a prospective study, patients 60 years or above with systolic heart failure NYHA II-IV were followed for at least 18 months. At study start, a physical examination, echocardiography, blood samples and measurements of quality of life (QoL) by Nottingham Health Profile were obtained. Data on mortality and readmission rates were collected.

RESULTS

208 patients, 58% men, with a mean age of 76 years, and an ejection fraction of 0.34 were included and followed for a mean of 1,122 days. In all, 74 (36%) patients died and 171 (82%) were readmitted. By univariate analysis, readmissions were predicted by poor QoL (169 +/- 118 vs. 83 +/- 100, p < 0.001), age, creatinine, haemoglobin (p < 0.01 all) and diabetes (p < 0.1). By multivariate analyses, QoL at study start was the only independent predictor of readmissions (chi(2) = 25.2, p < 0. 001). Mortality was univariately associated with QoL (183 +/- 117 vs. 142 +/- 115, p < 0.05) and in multivariate analyses to traditional variables: age, male gender, systolic function, BNP and serum creatinine (chi(2) = 48.9, p < 0.001).

CONCLUSIONS

Measurements representing different aspects of the heart failure syndrome can easily be obtained to stratify long-term risks of mortality and morbidity in hospitalised heart failure patients. Poor QoL was a univariate predictor for mortality and a strong multivariate predictor for the important outcome of readmission, pointing to the need for a simple assessment of QoL.

Preoperative heart rate variability in relation to surgery outcome in refractory epilepsy

BACKGROUND

Epilepsy patients may have an impaired autonomic cardiac control, which has been associated with an increased incidence of sudden unexpected death among people with epilepsy (SUDEP). The risk of SUDEP is particularly high among epilepsy surgery candidates with refractory epilepsy. This risk seems to be reduced after successful surgery but whether this is an effect of surgery or reflects pre-existing differences between good and poor responders is under debate.

METHODS

We used spectral analysis to analyze prospectively heart rate variability (HRV) preoperatively in 21 consecutive patients with temporal lobe epilepsy who were planned for epilepsy surgery. The presurgical HRV based on ambulatory 24 hours EKG recordings was analyzed in relation to seizure control at 1 year after surgery.

RESULTS

Patients had significantly lower SD of RR-intervals, total power, very low frequency power and low frequency power than matched healthy controls. Patients with good outcome of surgery (Engel class I; n = 11) did not differ from their controls while those with poor outcome (Engel class II-IV; n = 10) had significantly lower power in all domains than those with a favorable outcome.

CONCLUSIONS

Measurements of heart rate variability preoperatively indicate that patients with a poor outcome of surgery have a more pronounced impairment of sympathetic as well as parasympathetic cardiac control than those with good outcome. Reduced heart rate variability may be associated with an increased risk of sudden unexpected death among people with epilepsy (SUDEP). Good surgery candidates may a priori have a lower risk of SUDEP.

Acute barium nitrate intoxication treated by hemodialysis

A 22-year-old male was admitted to hospital with diarrhea and vomiting, cardiac arrhythmias, severe hypokalemia and gradual onset of muscular weakness. A potassium infusion was started, but for several hours serum potassium remained low. Evidence of toxic ingestion was initially lacking. When it became clear -- after a considerable delay -- that the patient had ingested barium nitrate, hemodialysis was started. This resulted in rapid clinical improvement with correction of hypokalemia and restored muscular function. Intoxication with barium causes hypokalemia, arrhythmias, muscular weakness and paralysis, often requiring respiratory support. This patient presented with symptoms typical of severe barium intoxication, non-responsive to potassium supplementation. There are few published reports on the use of hemodialysis in barium poisoning. This case confirms the possible benefit of hemodialysis in severe cases, where potassium supplementation alone is insufficient.

Effect of carvedilol on diastolic function in patients with diastolic heart failure and preserved systolic function. Results of the Swedish Doppler-echocardiographic study (SWEDIC)

AIM

The purpose of this study was to investigate the effects of carvedilol on diastolic function (DF) in heart failure patients with preserved left ventricular (LV) systolic function and abnormal DF.

PATIENTS AND METHODS

We randomised 113 patients with diastolic heart failure (DHF) (symptomatic, with normal systolic LV function and abnormal DF) into a double blind multi-centre study. The patients received either carvedilol or matching placebo in addition to conventional treatment. After uptitration, treatment was continued for 6 months. Two-dimensional and Doppler echocardiography were used for quantification of LV function at baseline and at follow-up. Four different DF variables were evaluated by Doppler echocardiography: mitral flow E:A ratio, deceleration time (DT), isovolumic relaxation time (IVRT) and the ratio of systolic/diastolic pulmonary venous flow velocity (pv-S/D). Primary endpoint was change in the integrated quantitative assessment of all four variables during the study.

RESULTS

Ninety-seven patients completed the study. A mitral flow pattern reflecting a relaxation abnormality was recorded in 95 patients. There was no effect on the primary endpoint, although a trend towards a better effect in carvedilol treated patients was noticed in patients with heart rates above 71 beats per minute. At the end of the study, there was a statistically significant improvement in E:A ratio in patients treated with carvedilol (0.72 to 0.83) vs. placebo (0.71 to 0.76), P<0.05.

CONCLUSIONS

Treatment with carvedilol resulted in a significant improvement in E:A ratio in patients with heart failure due to a LV relaxation abnormality. E:A ratio was found to be the most useful variable to identify diastolic dysfunction in this patient population. This effect was observed particularly in patients with higher heart rates at baseline.

Limited long term effects of a management programme for heart failure

OBJECTIVE

To evaluate the effects of a nurse based outpatient management programme for elderly patients discharged with heart failure from a university hospital.

DESIGN

Patients with heart failure (New York Heart Association class II-IV) and left ventricular systolic dysfunction aged 60 years or more were randomly assigned to follow up within the management programme or to conventional follow up, usually in primary care. Of the 208 participants, 58% were men, mean age was 75 years, and mean ejection fraction 34%. All patients were scheduled for three observational study visits at six month intervals. The primary end point was quality of life (QoL) and secondary end points were hospitalisation and mortality.

RESULTS

More patients achieved target doses of angiotensin converting enzyme (ACE) inhibitors in the intervention group than in the control group (82% v 69%, 88% v 69%, and 88% v 74% of recommended target doses at 6, 12, and 18 months of follow up, respectively, p < 0.05 for all). Patients with initial low QoL had a poor prognosis. After a mean 1122 days of follow up, 82% of all patients had been readmitted. There were on average 4.7 readmissions per patient and 66% were due to non-cardiac diagnoses. There were no differences in QoL or health care consumption between the two study groups during follow up.

CONCLUSION

A nurse based management programme is more effective than follow up in primary care in optimising medication for elderly patients with heart failure. However, such a programme does not seem to have a favourable influence on QoL or readmission rate during long term follow up.

The bile acid independent flow is reduced in the transplanted liver

Bile secretion is an important indicator of liver graft function. Reports on bile formation by the transplanted liver with stable function some months after operation are scarce. In this study bile flow, bile salt secretion rate (BSSR) and biliary clearance of polyethylene glycol (PEG) 900, a marker of canalicular bile flow, were studied in a group of liver-transplanted (LTX) patients (n = 8) 3-6 months after transplantation. A group of cholecystectomized patients with indwelling T-tubes (n = 6) served as a control group. Both groups were treated with oral ursodeoxycholic acid (500 mg/day). On the day of the study bile was drained for 6 h by gravity and four-hourly samples were used in the calculations. The relation between bile flow and BSSR analysed with linear regression showed a reduced bile acid independent flow in the liver-transplanted group (0.11 ml/min) compared with the control group (0.20 ml/min). The relation between biliary clearance of PEG 900 and BSSR showed a significantly steeper slope for the cholecystectomized control patients (1.40 ml/micromol) compared with the liver-transplanted patients (0.30 ml/micromol). We conclude, that in spite of stable graft function with normal liver enzmyes, the transplanted liver has a reduced bile acid independent bile flow. The transplanted liver also has a reduced biliary clearance of PEG 900 indicating a reduced canalicular bile flow. The cause of this impaired bile formation could be due to the influence of the immunosuppressive drug cyclosporin, the result of damage to the liver during preservation and reperfusion or the continuous immunological challenge to the graft.

Ventilatory variables are strong prognostic markers in elderly patients with heart failure

OBJECTIVE

To evaluate the safety and prognostic capacity of cardiopulmonary exercise testing in patients > or = 60 years old who are hospitalised with heart failure caused by left ventricular dysfunction.

DESIGN

Prospective study.

SETTING

University hospital.

PATIENTS

Study participants were 67 patients (66% men) with clinical heart failure stabilised on medical treatment. The study is a part of a nursing intervention study. Mean (SD) age was 74 (6) years, New York Heart Association functional class II-III, and ejection fraction 0.36 (0.11).

INTERVENTIONS

Cardiopulmonary exercise testing and echocardiography.

MAIN OUTCOME MEASURES

Peak oxygen consumption (VO2), peak ventilatory equivalents for carbon dioxide (VE/VCO2) and oxygen (VE/VO2), left ventricular volumes, and mortality.

RESULTS

Mean (SD) peak VO2 was 11.7 (3.7) ml/kg/min, peak VE/VCO2 43 (9), and peak VE/VO2 46 (11). During 12-59 months of follow up, 14 patients died. In univariate analyses peak VO2, VE/VO2, and VE/VCO2 were all strongly related (p < 0.01) to mortality. In a multivariate Cox regression analysis, peak VE/VCO2 was the strongest predictor of mortality (p < 0.001), followed by left ventricular end systolic volume (p < 0.001). A cut off of peak VE/VCO2 at > or = 45 gave a univariate hazard ratio of 6.7 for death during follow up. No adverse events occurred during the exercise test.

CONCLUSION

These findings extend results found in selected middle aged patients to elderly patients with heart failure and show that ventilatory parameters from a cardiopulmonary exercise test, such as peak VO2, VE/O2, and VE/VCO2 are powerful predictors of mortality.

Envenoming by European vipers antivenom treatment--influence on morbidity

The incidence of venomous viper bites in Europe is difficult to assess. Mortality after bites by European vipers is nowadays low, but morbidity is by no means negligible. Serious and life-threatening reactions occur, especially in small children and elderly people. The critically ill can nowadays be managed with symptomatic and supportive care in an astonishing way, but antivenom treatment may reduce the extent of such treatment and also reduced the overall risk for the patient. In particular, the only way to prevent extensive swelling and related complications is to give antivenom. The aim of this study was to test efficacy and safety of ovine Fab (a new specific ovine Fab fragments against various snake venoms) as an alternative to equine F(ab)2 antibodies in patients presenting with moderate and severe envenoming.

Epidemiology of heart failure in Sweden--a national survey

BACKGROUND

In Sweden heart failure is the most frequent discharge diagnosis within internal medicine. The prevalence of heart failure seems to be increasing, mainly due to an ageing population, but also because of improved survival in patients with cardiovascular diseases.

AIM

To describe the epidemiology of heart failure in Sweden from a perspective based on demographic and health care data.

METHODS

The national registers in Sweden provide detailed information on health care consumption in relation to different diagnoses. Pharmaceutical sales are also registered. There are national epidemiological reports, reports on health care utilization and on health economics concerning heart failure patients.

RESULTS

There has been structural changes in the Swedish health care system due to financial restraints in the health care budget. Aiming at reducing hospital costs, the total amount of hospital beds has been cut down markedly during the last decade. The number of heart failure patients and the number of hospital stays have increased during the same period. Hospital stays have become shorter. The number of patients and hospital stays more than double when heart failure as both primary and secondary discharge diagnoses are included.

CONCLUSION

The available national registers provide a good opportunity to study epidemiology of heart failure in Sweden. The number of hospital beds has decreased markedly within the last decade due to changes in the Swedish health care system. Nevertheless, there has been an increase in the number of patients discharged with heart failure from the hospitals, suggesting an increase in prevalence.

Doppler tissue imaging in congestive heart failure patients due to diastolic or systolic dysfunction: a comparison with Doppler echocardiography and the atrio-ventricular plane displacement technique

BACKGROUND

Doppler tissue imaging (DTI) is an echocardiographic technique by which regional contractility, relaxation properties and time intervals are obtained easily. DTI has been reported to be relatively pre-load independent and could, in comparison with the commonly used mitral pulse wave Doppler (MPWD) method, be of clinical interest for identification of patients with diastolic dysfunction. The atrio-ventricular plane displacement (AVPD) method is an established technique to assess left ventricular systolic function.

AIMS

To determine the pulsed Doppler DTI-pattern in patients with heart failure and to examine whether it has a similar capacity as MPWD and AVPD to diagnose diastolic dysfunction.

METHODS

We studied 15 controls without congestive heart failure (CHF), 15 patients with diastolic (EF>45%+CHF) and 15 patients with systolic (EF<35%+CHF) left ventricular dysfunction and CHF.

RESULTS

The DTI maximal velocities during systole (s), early filling wave (e) and atrial filling wave (a), decrease with reduced left ventricular ejection fraction, r=0.75, r=0.56 and r=0.66 (P<0.001) and regional isovolumetric contraction and intraventricular relaxation time measured by DTI are prolonged, r=0.59 and r=0.73, respectively (P<0.001). The 15 patients with diastolic heart failure were identified by MPWD or DTI but only 11 by AVPD with 8, 10 and 9 false-positive, respectively (P<0.01, P<0.05 and NS).

CONCLUSIONS

Regional DTI show a consistent pattern in patients with left ventricular dysfunction and heart failure. Regional DTI has similar accuracy as MPWD in identifying diastolic heart failure patients and is superior to the AVPD technique. DTI may be a useful diagnostic tool in diastolic heart failure patients.

Immunostaining of ganglioside GD1b, GD3 and GM1 in rat cerebellum: cellular layer and cell type specific associations

We have studied the cellular distribution of gangliosides GD1b, GD3 and GM1 in rat cerebellum by immunostaining, using monoclonal antibodies and confocal microscopy. Antibodies against astroglial, neuronal and synaptic vesicle associated molecules were used for colocalization analyses. In the gray matter, the anti-GD1b antibody stained thin strands in the molecular layer (ML), interpreted as Bergman glia fibers based on colocalized staining with anti-glial fibrillary acidic protein (GFAP). The neuropil in the granule (GL) and Purkinje (PL) cell layers was also anti-GD1b positive. The anti-GD3 antibody stained the ML, the neuropil in the GL and PL and also the granule and Purkinje cell bodies, appearing intracytoplasmically and vesicle associated. Anti-GD1b and anti-GD3 staining in the GL glomeruli were colocalized with anti-synaptophysin staining. The anti-GM1 antibody stained cell bodies in the ML but they could not be characterized in colocalization experiments. The GL and PL were not stained with the anti-GM1 antibody. In the white matter, different staining patterns were seen for the gangliosides, the anti-GM1 staining being the most intense. This study shows cellular layer and cell type specific associations of the investigated gangliosides and localization of GD1b and GD3 at synaptic sites, warranting further studies on their role in synaptic mechanisms.