JS04.6.A The landscape of tumor cell states and spatial organization in H3-K27M mutant diffuse midline glioma across age and location

Background

Histone 3 lysine27-to-methionine mutations (H3-K27M) frequently occur in childhood diffuse midline gliomas (DMGs) of the pons, thalamus and spinal cord, presumed to be driven by the specific spatiotemporal context of these midline locations during postnatal development. While most common in the pons and at mid-childhood ages, the same oncohistone mutation is recurrently detected in adult DMGs and throughout different midline regions. The potential heterogeneity of tumors at different ages and in different anatomical locations of the midline are vastly understudied.

Material and Methods

Through dissecting the transcriptomic, epigenomic and spatial architectures of a comprehensive cohort of patient H3-K27M DMGs - spanning the age range from 2-68 years and locations from spinal cord to thalamus - at single cell resolution, we delineate how age- and location-dependent contexts shape glioma cell-intrinsic and -extrinsic features in light of the shared driver mutation.

Results

We identify that oligodendrocyte precursor (OPC)-like cells constitute the stem-like compartment in H3-K27M DMGs across all clinico-anatomical groups, however, depending on location, display varying levels of maturity resembling less differentiated pre-OPCs or more mature OPCs further differentiated along the oligodendroglial lineage. We further demonstrate increased mesenchymal cell states in adult tumors, which we link to age-related differences in glioma-associated immune cell compartments. We for the first time resolve the spatial organization of H3-K27M DMG cell types in intact patient tissues, identifying a local niche of the oligodendroglial lineage.

Conclusion

Our study provides a powerful resource for rational modeling and therapeutic frameworks taking into account determinants of age and location in this lethal glioma group.

Severity of oEsophageal Anastomotic Leak in patients after oesophagectomy: the SEAL score

Background

Anastomotic leak (AL) is a common but severe complication after oesophagectomy. It is unknown how to determine the severity of AL objectively at diagnosis. Determining leak severity may guide treatment decisions and improve future research. This study aimed to identify leak-related prognostic factors for mortality, and to develop a Severity of oEsophageal Anastomotic Leak (SEAL) score.

Methods

This international, retrospective cohort study in 71 centres worldwide included patients with AL after oesophagectomy between 2011 and 2019. The primary endpoint was 90-day mortality. Leak-related prognostic factors were identified after adjusting for confounders and were included in multivariable logistic regression to develop the SEAL score. Four classes of leak severity (mild, moderate, severe, and critical) were defined based on the risk of 90-day mortality, and the score was validated internally.

Results

Some 1509 patients with AL were included and the 90-day mortality rate was 11.7 per cent. Twelve leak-related prognostic factors were included in the SEAL score. The score showed good calibration and discrimination (c-index 0.77, 95 per cent c.i. 0.73 to 0.81). Higher classes of leak severity graded by the SEAL score were associated with a significant increase in duration of ICU stay, healing time, Comprehensive Complication Index score, and Esophagectomy Complications Consensus Group classification.

Conclusion

The SEAL score grades leak severity into four classes by combining 12 leak-related predictors and can be used to the assess severity of AL after oesophagectomy.

SABRE-enhanced real-time pure shift NMR spectroscopy

Pure shift nuclear magnetic resonance (NMR) methods suppress the effect of homonuclear scalar couplings to produce NMR spectra consisting solely of a single signal for each chemically distinct site. They are increasingly relied upon for analysis of complex molecules and mixtures as they overcome the extensive signal overlap that complicates proton NMR spectra of all but the simplest species. Current broadband pure shift methodologies for 1D proton spectra suffer from reduced sensitivity compared with their conventional counterparts and typically require a large amount of instrument time for low concentration samples. In this study, we demonstrate how the sensitivity limitation may be overcome by transiently increasing the bulk polarization using signal amplification by reversible exchange (SABRE) hyperpolarization. We utilize para-enriched dihydrogen to enhance the pure shift NMR resonances of pyridine by up to a factor of 60 in a single-scan experiment and extend this to propose a method to unambiguously determine mixture components based on the enhancement of their pure shift NMR signals.

Mentorship during undergraduate surgical training: comparing perceptions of medical students and faculty at two institutions in South Africa and Sweden

BACKGROUND

Having a mentor during undergraduate surgical training has been shown to positively influence medical students by increasing interest in surgery, improving confidence, and assisting in career planning. This study aimed to evaluate and compare medical student and faculty perceptions of mentorship during undergraduate surgical training and compare results between two teaching institutions in South Africa and Sweden.

METHODS

An electronic, online questionnaire was anonymously distributed to medical students and general surgical faculty at the University of Cape Town (UCT), South Africa, and Karolinska Institutet (KI), Stockholm, Sweden. The questionnaire consisted of multiple choice, true or false, and five-point Likert scale questions, exploring perceptions of mentorship and role models, as well as rating the most important mentor characteristics.

RESULTS

Approximately one third (34.2%) of students stated they had a mentor during their surgical training, with significant differences found between student cohorts (p < 0.001). The 'registrar' was most commonly reported as the best role model for medical students by faculty from both UCT (50.0%) and KI (69.4%), as well as UCT students (36.6%). Students rated the following mentor qualities significantly higher compared to faculty: student encouragement (p = 0.037), adequate supervision (p = 0.007), setting of fair expectations (p = 0.002), and teaching skills (p = 0.010).

CONCLUSION

With significant differences existing in the perceptions of medical students and faculty regarding mentorship and role models during undergraduate surgical training in both South African and Swedish institutions, reconciling and harmonising these differences will be crucial in fostering constructive mentoring relationships.

Effect of SGLT2 inhibition on coronary microvascular function in patients with type 2 diabetes

Background

Treatment with sodium-glucose cotransporter 2 (SGLT2) inhibitor reduces risk of cardiovascular death and heart failure but the underlying mechanisms remain poorly understood. It has been suggested that a shift in fuel source in the myocardium from glucose and free fatty acids to the more energy efficient ketogenesis reduces oxidative stress involved in coronary microvascular damage, leading to improved coronary microvascular function.

Purpose

To test the hypothesis that treatment with the SGLT2 inhibitor empagliflozin improves non-endothelial dependent coronary microvascular function.

Methods

We included 26 patients with type 2 diabetes in a double blinded, placebo-controlled cross-over study. Participants were treated with empagliflozin 25 mg and placebo for 12 weeks, interrupted by 2 weeks wash-out period. The primary outcome was change in coronary microvascular function, assessed as coronary flow velocity reserve (CFVR) and measured with transthoracic doppler echocardiography. Secondary endpoints were change in echocardiographic parameters of cardiac systolic function and 184 cardiovascular protein biomarkers.

Results

Nineteen patients completed both study periods according to protocol. There was a significant weight loss and reduction in Hba1c after empagliflozin treatment (table). We found no improvement in CFVR and parameters of cardiac systolic function. We observed a general tendency of reduction in level of cardiovascular biomarkers after empagliflozin treatment (figure) with significant difference between empagliflozin and placebo for 27 proteins, including IL18, ST2, YKL40, ACE2 and leptin.

Conclusions

Despite a significant weight loss and reduction in Hba1c after empagliflozin treatment, we found no effect on non-endothelial dependent coronary microvascular function in patients with type 2 diabetes mellitus. Improvement in multiple biomarkers may indicate underlying mechanisms but need confirmation in larger studies.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The Danish Council for Independent Research Table 1. Change in outcome parametersFigure 1. Change in biomarker levels

Signal-to-noise ratio in diffusion-ordered spectroscopy: how good is good enough?

Diffusion-ordered NMR spectroscopy (DOSY) constructs multidimensional spectra displaying signal strength as a function of Larmor frequency and of diffusion coefficient from experimental measurements using pulsed field gradient spin or stimulated echoes. Peak positions in the diffusion domain are determined by diffusion coefficients estimated by fitting experimental data to some variant of the Stejskal-Tanner equation, with the peak widths determined by the standard error estimated in the fitting process. The accuracy and reliability of the diffusion domain in DOSY spectra are therefore determined by the uncertainties in the experimental data and thus in part by the signal-to-noise ratio of the experimental spectra measured. Here the Cramér-Rao lower bound, Monte Carlo methods, and experimental data are used to investigate the relationship between signal-to-noise ratio, experimental parameters, and diffusion domain accuracy in 2D DOSY experiments. Experimental results confirm that sources of error other than noise put an upper limit on the improvement in diffusion domain accuracy obtainable by time averaging.

Incidence, detection and outcome of differentiated thyroid cancer in Western Sweden

Background

It is unclear whether the increasing incidence of thyroid cancer (TC) due to increased diagnosis of small and indolent tumours might mask a real increase of clinically significant cancers. The aim of this study was to correlate surgery, pathology and outcome data of individual patients to the mode of primary detection (palpation, by imaging or incidental) to assess if TC incidence has increased.

Methods

The Swedish Cancer Registry identified all patients with TC in Västra Götaland County representing approximately 1.6 million inhabitants. Clinical information was retrieved from medical records of patient cohorts from three study intervals (2001–2002, 2006–2007 and 2011–2014) comprising 60 per cent of all TC patients. Data were also obtained from the NORDCAN registry to compare of TC incidence with other Nordic countries.

Results

Between 2001 and 2014, the annualized standard incidence rate/100 000 population (ASR) of TC increased from 3.14 to 10.71 in women and from 1.12 to 3.77 in men. This was higher than the mean incidence for Sweden but similar to that in Norway and Finland. Differentiated TC (DTC) increased more than threefold. The majority of tumours (64 per cent) were detected by palpation. Larger tumours (10–20, 21–40 and greater than 40 mm) increased as much as microcarcinomas (less than 10 mm). Only 5 per cent of the tumours were detected by imaging. All disease-specific deaths (8.5 per cent of DTC in the first two cohorts) and most patients with recurrent or persistent disease (6.6 per cent of DTC cases) were diagnosed due to tumour-related symptoms.

Conclusion

DTC in Western Sweden gradually increased between 2001 and 2014. The majority of tumours were detected by palpation suggesting a real increase in the incidence of clinically significant thyroid malignancies.

Broadband measurement of true transverse relaxation rates in systems with coupled protons: application to the study of conformational exchange

Accurate measurement of transverse relaxation rates in coupled spin systems is important in the study of molecular dynamics, but is severely complicated by the signal modulations caused by scalar couplings in spin echo experiments. The most widely used experiments for measuring transverse relaxation in coupled systems, CPMG and PROJECT, can suppress such modulations, but they also both suppress some relaxation contributions, and average relaxation rates between coupled spins. Here we introduce a new experiment which for the first time allows accurate broadband measurement of transverse relaxation rates of coupled protons, and hence the determination of exchange rate constants in slow exchange from relaxation measurements. The problems encountered with existing methods are illustrated, and the use of the new method is demonstrated for the classic case of hindered amide rotation and for the more challenging problem of exchange between helical enantiomers of a gold(i) complex.

Fit-for-Discharge Criteria after Esophagectomy: An International Expert Delphi Consensus

There are no internationally recognized criteria available to determine preparedness for hospital discharge after esophagectomy. This study aims to achieve international consensus using Delphi methodology. The expert panel consisted of 40 esophageal surgeons spanning 16 countries and 4 continents. During a 3-round, web-based Delphi process, experts voted for discharge criteria using 5-point Likert scales. Data were analyzed using descriptive statistics. Consensus was reached if agreement was ≥75% in round 3. Consensus was achieved for the following basic criteria: nutritional requirements are met by oral intake of at least liquids with optional supplementary nutrition via jejunal feeding tube. The patient should have passed flatus and does not require oxygen during mobilization or at rest. Central venous catheters should be removed. Adequate analgesia at rest and during mobilization is achieved using both oral opioid and non-opioid analgesics. All vital signs should be normal unless abnormal preoperatively. Inflammatory parameters should be trending down and close to normal (leucocyte count ≤12G/l and C-reactive protein ≤80 mg/dl). This multinational Delphi survey represents the first expert-led process for consensus criteria to determine 'fit-for-discharge' status after esophagectomy. Results of this Delphi survey may be applied to clinical outcomes research as an objective measure of short-term recovery. Furthermore, standardized endpoints identified through this process may be used in clinical practice to guide decisions regarding patient discharge and may help to reduce the risk of premature discharge or prolonged admission.

Patient-reported outcomes after oesophagectomy in the multicentre LASER study

BACKGROUND

Data on the long-term symptom burden in patients surviving oesophageal cancer surgery are scarce. The aim of this study was to identify the most prevalent symptoms and their interactions with health-related quality of life.

METHODS

This was a cross-sectional cohort study of patients who underwent oesophageal cancer surgery in 20 European centres between 2010 and 2016. Patients had to be disease-free for at least 1 year. They were asked to complete a 28-symptom questionnaire at a single time point, at least 1 year after surgery. Principal component analysis was used to assess for clustering and association of symptoms. Risk factors associated with the development of severe symptoms were identified by multivariable logistic regression models.

RESULTS

Of 1081 invited patients, 876 (81.0 per cent) responded. Symptoms in the preceding 6 months associated with previous surgery were experienced by 586 patients (66.9 per cent). The most common severe symptoms included reduced energy or activity tolerance (30.7 per cent), feeling of early fullness after eating (30.0 per cent), tiredness (28.7 per cent), and heartburn/acid or bile regurgitation (19.6 per cent). Clustering analysis showed that symptoms clustered into six domains: lethargy, musculoskeletal pain, dumping, lower gastrointestinal symptoms, regurgitation/reflux, and swallowing/conduit problems; the latter two were the most closely associated. Surgical approach, neoadjuvant therapy, patient age, and sex were factors associated with severe symptoms.

CONCLUSION

A long-term symptom burden is common after oesophageal cancer surgery.

Executive functioning in psychiatric patients with deliberate self-harm, as compared with a psychiatric and a healthy comparison group

Introduction: Deliberate self-harm (DSH) is a common symptom in psychiatric disorders. It is a cross-diagnostic symptom, although it has mainly been associated with borderline personality disorder (BPD). Research has suggested an association between DSH and deficits in executive functioning. The main aim of the current study was to assess three specific aspects of executive functioning (EF) (working memory, inhibition and cognitive flexibility) among psychiatric patients with DSH, compared to a clinical and a healthy comparison group.Methods: Thirty psychiatric patients with DSH, 29 psychiatric patients without DSH and 29 healthy individuals were assessed with regard to psychiatric illness, self-harming behavior, EF, general cognitive functioning level and measures of psychopathology. The results were analyzed by means of ANOVA, regression analysis, Chi-square, and correlation analysis.Results: The patients with DSH showed deficits in cognitive flexibility and inhibition as compared to healthy individuals. In addition, the patients with DSH had greater deficits in cognitive flexibility than the patients without DSH; this effect was independent of concurrent severity of depressive symptoms but not independent of borderline symptomatology.Conclusion: Psychiatric patients with DSH may have deficits in cognitive flexibility as compared to both the healthy and clinical comparison groups. The results partly differ from previous related studies in the field. It is unclear to which extent the deficits in cognitive flexibility are due to other factors. More research is needed to understand the implications of such deficits, and if the results could be used for adapting treatment services and strategies. Future studies should include more similar comparison groups.

Mortality after surgery for primary hyperparathyroidism: results from a nationwide cohort

BACKGROUND

Contemporary patients with primary hyperparathyroidism are often diagnosed with mildly raised serum calcium levels. Previous studies have reported increased mortality in patients with primary hyperparathyroidism. This retrospective cohort study aimed to examine whether contemporary patients operated for primary hyperparathyroidism have higher mortality than the general population, and whether mortality in these patients is associated with serum calcium concentration, adenoma weight or multiglandular disease.

METHODS

Patients from a Swedish national cohort consisting of patients registered in the Scandinavian Quality Register for Thyroid, Parathyroid, and Adrenal Surgery 2003-2013, were matched with population controls. The National Patient Register, the Swedish Cause of Death Register, and socioeconomic data were cross-linked. End of follow-up was 10 years after surgery, 31 December 2015, or emigration. Mortality was analysed by standardized mortality ratio, Kaplan-Meier survival estimates, and univariable and multivariable Cox regression. Multiple imputation by chained equations was performed on missing data.

RESULTS

After exclusions, there were 5009 patients with primary hyperparathyroidism and 14 983 controls. Multivariable Cox regression analysis adjusted for age, sex, Charlson Co-morbidity Index, marital status, level of education, disposable income, and period of surgery showed lower mortality in patients than controls (hazard ratio (HR) 0.83, 95 per cent c.i. 0.75 to 0.92). In univariable Cox regression of mortality in patients, serum calcium concentration (mmoles per litre) was associated with mortality (HR 2.20, 1.53 to 3.16). This association remained in multivariable Cox regression after multiple imputation (HR 1.79, 1.19 to 2.70).

CONCLUSION

Mortality was not increased in patients operated for primary hyperparathyroidism compared with controls in a contemporary setting. Preoperative serum calcium concentration might, however, influence survival.

Single-scan ultra-selective 1D total correlation spectroscopy

Selective 1D TOCSY is a powerful tool in the assignment of NMR spectra of organic molecules. Here an order of magnitude improvement in selectivity, allowing overlapping multiplets to be excited separately, is achieved in a single scan using the very recent GEMSTONE method. The new experiment is illustrated using an antibiotic and a mixture of diastereomers.

Single-Scan Selective Excitation of Individual NMR Signals in Overlapping Multiplets

2D NMR is an immensely powerful structural tool but it is time-consuming. Targeting individual chemical groups by selective excitation in a 1D experiment can give the information required far more quickly. A major problem, however, is that proton NMR spectra are often extensively overlapped, so that in practice only a minority of sites can be selectively excited. Here we overcome that problem using a fast, single-scan method that allows selective excitation of the signals of a single proton multiplet even where it is severely overlapped by other multiplets. The advantages of the method are illustrated in a selective 1D NOESY experiment, the most efficient way to determine relative configuration unambiguously by NMR. The new approach presented here has the potential to broaden significantly the applicability of selective excitation and unlock its real potential for many other experiments.

Impact of co-morbidity on reoperation or death within 90 days of surgery for oesophageal cancer

Background

The impact of preoperative co-morbidity on postoperative outcomes in patients with oesophageal cancer is uncertain. A population-based and nationwide cohort study was conducted to assess the influence of preoperative co-morbidity on the risk of reoperation or mortality within 90 days of surgery for oesophageal cancer.

Methods

This study enrolled 98 per cent of patients who had oesophageal cancer surgery between 1987 and 2015 in Sweden. Modified Poisson regression models provided risk ratios (RRs) with 95 per cent confidence intervals (c.i.) to estimate associations between co-morbidity and risk of reoperation or death within 90 days of oesophagectomy. The RRs were adjusted for age, sex, educational level, pathological tumour stage, neoadjuvant therapy, annual hospital volume, tumour histology and calendar period of surgery.

Results

Among 2576 patients, 446 (17.3 per cent) underwent reoperation or died within 90 days of oesophagectomy. Patients with a Charlson Co-morbidity Index (CCI) score of 2 or more had an increased risk of reoperation or death compared with those with a CCI score of 0 (RR 1.78, 95 per cent c.i. 1.44 to 2.20), and the risk increased on average by 27 per cent for each point increase of the CCI (RR 1.27, 1.18 to 1.37). The RR was increased in patients with pulmonary disease (RR 1.66, 1.36 to 2.04), cardiac disease (RR 1.37, 1.08 to 1.73), diabetes (RR 1.50, 1.14 to 1.99) and cerebral disease (RR 1.40, 1.06 to 1.85).

Conclusion

Co-morbidity in general, and pulmonary disease, cardiac disease, diabetes and cerebral disease in particular, increased the risk of reoperation or death within 90 days of oesophageal cancer surgery. This highlights the value of tailored patient selection, preoperative preparation and postoperative care.

Mentorship during undergraduate surgical training: comparing perceptions of medical students and faculty at two institutions in South Africa and Sweden

ABSTRACT BACKGROUND: Having a mentor during undergraduate surgical training has been shown to positively influence medical students by increasing interest in surgery, improving confidence, and assisting in career planning. This study aimed to evaluate and compare medical student and faculty perceptions of mentorship during undergraduate surgical training and compare results between two teaching institutions in South Africa and Sweden METHODS: An electronic, online questionnaire was anonymously distributed to medical students and general surgical faculty at the University of Cape Town (UCT), South Africa, and Karolinska Institutet (KI), Stockholm, Sweden. The questionnaire consisted of multiple choice, true or false, and five-point Likert scale questions, exploring perceptions of mentorship and role models, as well as rating the most important mentor characteristics RESULTS: Approximately one third (34.2%) of students stated they had a mentor during their surgical training, with significant differences found between student cohorts (p < 0.001). The 'registrar' was most commonly reported as the best role model for medical students by faculty from both UCT (50.0%) and KI (69.4%), as well as UCT students (36.6%). Students rated the following mentor qualities significantly higher compared to faculty: student encouragement (p = 0.037), adequate supervision (p = 0.007), setting of fair expectations (p = 0.002), and teaching skills (p = 0.010 CONCLUSION: With significant differences existing in the perceptions of medical students and faculty regarding mentorship and role models during undergraduate surgical training in both South African and Swedish institutions, reconciling and harmonising these differences will be crucial in fostering constructive mentoring relationships Keywords: mentorship, role model, perception, surgical education

Impact of surgical resection rate on survival in gastric cancer: nationwide study

Background

There are marked geographical variations in the proportion of patients undergoing resection for gastric cancer. This study investigated the impact of resection rate on survival.

Methods

All patients with potentially curable gastric cancer between 2006 and 2017 were identified from the Swedish National Register of Oesophageal and Gastric Cancer. The annual resection rate was calculated for each county per year. Resection rates in all counties for all years were grouped into tertiles and classified as low, intermediate or high. Survival was analysed using the Cox proportional hazards model.

Results

A total of 3465 patients were diagnosed with potentially curable gastric cancer, and 1934 (55.8 per cent) were resected. Resection rates in the low (1261 patients), intermediate (1141) and high (1063) tertiles were 0–50.0, 50.1–62.5 and 62.6–100 per cent respectively. The multivariable Cox analysis revealed better survival for patients diagnosed in counties during years with an intermediate versus low resection rate (hazard ratio (HR) 0.81, 95 per cent c.i. 0.74 to 0.90; P < 0.001) and high versus low resection rate (HR 0.80, 0.73 to 0.88; P < 0.001).

Conclusion

This national register study showed large regional variation in resection rates for gastric cancer. A higher resection rate appeared to be beneficial with regard to overall survival for the entire population.

Effect of weight loss, exercise and risk factor control in microvascular angina. A randomized controlled pilot trial

Background

Coronary microvascular dysfunction (CMD) is a common cause of angina in women and associated with adverse cardiovascular prognosis. Currently, no evidence-based treatment for CMD exists.

Purpose

To examine whether an intervention targeting cardiovascular risk factors is feasible and improves angina symptoms and microvascular function in women with CMD and no obstructive coronary artery disease.

Methods

We randomized 62 women aged 40–75, with body mass index &gt;25 kg/m2, angina symptoms monthly or more and coronary flow velocity reserve (CFVR) &lt;2.5 to a 24-week intervention comprising low energy diet, exercise training, and optimized medical treatment of hypertension, dyslipidemia and diabetes or to usual care. Patients were assessed before randomization and after 24 weeks. The primary outcomes were CFVR assessed by transthoracic Doppler stress-echocardiography and angina burden measured by the Seattle Angina Questionnaire (SAQ). Secondary endpoints were exercise capacity (VO2max), body composition and glycemic control, anxiety and depression symptoms measured by the Hospital Anxiety and Depression Scale (HADS).

Results

Fifty-six participants (90%) completed the study. Median age was 65 years. The intervention group obtained a mean weight loss of 10 kg, mainly (9 kg) from fat tissue (all p&lt;0.0001), increased work load (p&lt;0.01), decreased triglycerides, low density lipoprotein and low plasma cholesterol (all p&lt;0.006). HbA1c in non-diabetes participants also decreased (p&lt;0.05).

There was a clinically relevant improvement in all angina symptoms (9–21-point increase on all SAQ scales (all p&lt;0.01)) as well as in depression score (p=0.008). There was no effect on CFVR or other secondary outcomes.

Conclusion

A major weight loss and intensified risk factor control resulted in significant improvement in angina burden but no improvement of coronary microvascular function among women with microvascular angina.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Unlimited research funding sources from the Capital region of Denmark and Bispebjerg-Frederiksberg Hospital internal funding sources.