Surgical Management of Ebstein Anomaly: The Australia and New Zealand Experience

BACKGROUND

Ebstein anomaly is a rare congenital anomaly of the tricuspid valve which presents challenges to cardiac surgeons due to the spectrum of the disease and the technical difficulty of valve repair. The natural history of the anomaly differs between patients presenting in the neonatal period to those presenting in adulthood.

METHODS

A retrospective review of all patients >15 years of age with Ebstein anomaly, undergoing surgery on the tricuspid valve at 6 centers across Australia and New Zealand was performed. Patients from 1985 to 2019 were included in the study.

RESULTS

A total of 125 patients were included in the study, 76 patients (60%) undergoing tricuspid valve repair, of which 23 patients underwent a Cone repair and 49 (40%) had a tricuspid valve replacement. The mean follow-up was 7.9 ± 7.3 years. Postoperatively, early mortality was 3 patients (2%) and 10-year survival was 91.5%. A postoperative pacemaker was required in 24 patients (19%). Reoperation was required in 21 patients (17%). There was no statistically significant difference in survival or reoperation between patients who underwent repair or replacement of the tricuspid valve; however, with a small number of patients in long-term follow-up.

CONCLUSION

Older children and adult patients undergoing surgery for Ebstein anomaly in Australia and New Zealand experience good medium-term postoperative survival. Repair of the valve is achieved in a significant proportion of patients with increasing use and success with the Cone repair technique.

Deep learning at the edge enables real-time streaming ptychographic imaging

Coherent imaging techniques provide an unparalleled multi-scale view of materials across scientific and technological fields, from structural materials to quantum devices, from integrated circuits to biological cells. Driven by the construction of brighter sources and high-rate detectors, coherent imaging methods like ptychography are poised to revolutionize nanoscale materials characterization. However, these advancements are accompanied by significant increase in data and compute needs, which precludes real-time imaging, feedback and decision-making capabilities with conventional approaches. Here, we demonstrate a workflow that leverages artificial intelligence at the edge and high-performance computing to enable real-time inversion on X-ray ptychography data streamed directly from a detector at up to 2 kHz. The proposed AI-enabled workflow eliminates the oversampling constraints, allowing low-dose imaging using orders of magnitude less data than required by traditional methods.

Linking scientific instruments and computation: Patterns, technologies, and experiences

Powerful detectors at modern experimental facilities routinely collect data at multiple GB/s. Online analysis methods are needed to enable the collection of only interesting subsets of such massive data streams, such as by explicitly discarding some data elements or by directing instruments to relevant areas of experimental space. Thus, methods are required for configuring and running distributed computing pipelines—what we call flows—that link instruments, computers (e.g., for analysis, simulation, artificial intelligence [AI] model training), edge computing (e.g., for analysis), data stores, metadata catalogs, and high-speed networks. We review common patterns associated with such flows and describe methods for instantiating these patterns. We present experiences with the application of these methods to the processing of data from five different scientific instruments, each of which engages powerful computers for data inversion,model training, or other purposes. We also discuss implications of such methods for operators and users of scientific facilities.

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Patterns for linking instruments and computers for online analysis are reviewed

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Methods are presented for capturing such “flows” in reusable forms

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The use of Globus automation services to run flows is described

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Implications of these methods for scientists and facilities are discussed

The industrial revolution transformed society via large-scale automation of manufacturing. Today, AI- and robotics-driven automation of scientific research seems set to usher in a new era of accelerated discovery. But just as the industrial revolution depended on new replicable and scalable manufacturing processes and methods for delivering the copious mechanical power required by those processes, so the automated discovery revolution demands new methods for implementing research automation processes and for connecting those processes to computing and data power. We present here new methods that address these essential needs by allowing scientists to capture common automation patterns in reusable flows and to embed such flows in a global trust, data, and computing fabric that enables instant access to powerful AI, simulation, and other computational capabilities. We use examples from synchrotron light sources to show how these methods can be realized in software and applied at scale.

Fixed-target serial crystallography at the Structural Biology Center

Serial synchrotron crystallography enables the study of protein structures under physiological temperature and reduced radiation damage by collection of data from thousands of crystals. The Structural Biology Center at Sector 19 of the Advanced Photon Source has implemented a fixed-target approach with a new 3D-printed mesh-holder optimized for sample handling. The holder immobilizes a crystal suspension or droplet emulsion on a nylon mesh, trapping and sealing a near-monolayer of crystals in its mother liquor between two thin Mylar films. Data can be rapidly collected in scan mode and analyzed in near real-time using piezoelectric linear stages assembled in an XYZ arrangement, controlled with a graphical user interface and analyzed using a high-performance computing pipeline. Here, the system was applied to two β-lactamases: a class D serine β-lactamase from Chitinophaga pinensis DSM 2588 and L1 metallo-β-lactamase from Stenotrophomonas maltophilia K279a.

High-Throughput Virtual Screening and Validation of a SARS-CoV-2 Main Protease Noncovalent Inhibitor

Despite the recent availability of vaccines against the acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the search for inhibitory therapeutic agents has assumed importance especially in the context of emerging new viral variants. In this paper, we describe the discovery of a novel noncovalent small-molecule inhibitor, MCULE-5948770040, that binds to and inhibits the SARS-Cov-2 main protease (Mpro) by employing a scalable high-throughput virtual screening (HTVS) framework and a targeted compound library of over 6.5 million molecules that could be readily ordered and purchased. Our HTVS framework leverages the U.S. supercomputing infrastructure achieving nearly 91% resource utilization and nearly 126 million docking calculations per hour. Downstream biochemical assays validate this Mpro inhibitor with an inhibition constant (Ki) of 2.9 μM (95% CI 2.2, 4.0). Furthermore, using room-temperature X-ray crystallography, we show that MCULE-5948770040 binds to a cleft in the primary binding site of Mpro forming stable hydrogen bond and hydrophobic interactions. We then used multiple μs-time scale molecular dynamics (MD) simulations and machine learning (ML) techniques to elucidate how the bound ligand alters the conformational states accessed by Mpro, involving motions both proximal and distal to the binding site. Together, our results demonstrate how MCULE-5948770040 inhibits Mpro and offers a springboard for further therapeutic design.

2'-O methylation of RNA cap in SARS-CoV-2 captured by serial crystallography

The genome of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coronavirus has a capping modification at the 5'-untranslated region (UTR) to prevent its degradation by host nucleases. These modifications are performed by the Nsp10/14 and Nsp10/16 heterodimers using S-adenosylmethionine as the methyl donor. Nsp10/16 heterodimer is responsible for the methylation at the ribose 2'-O position of the first nucleotide. To investigate the conformational changes of the complex during 2'-O methyltransferase activity, we used a fixed-target serial synchrotron crystallography method at room temperature. We determined crystal structures of Nsp10/16 with substrates and products that revealed the states before and after methylation, occurring within the crystals during the experiments. Here we report the crystal structure of Nsp10/16 in complex with Cap-1 analog (m7GpppAm2'-O). Inhibition of Nsp16 activity may reduce viral proliferation, making this protein an attractive drug target.

Real-time HEP analysis with funcX, a high-performance platform for function as a service

We explore how the function as a service paradigm can be used to address the computing challenges in experimental high-energy physics at CERN. As a case study, we use funcX—a high-performance function as a service platform that enables intuitive, flexible, efficient, and scalable remote function execution on existing infrastructure—to parallelize an analysis operating on columnar data to aggregate histograms of analysis products of interest in real-time. We demonstrate efficient execution of such analyses on heterogeneous resources.

Canadian Plastic Surgery Resident Work Hour Restrictions: Practices and Perceptions of Residents and Program Directors

Background

The impact of resident work hour restrictions on training and patient care remains a highly controversial topic, and to date, there lacks a formal assessment as it pertains to Canadian plastic surgery residents.

Objective

To characterize the work hour profile of Canadian plastic surgery residents and assess the perspectives of residents and program directors regarding work hour restrictions related to surgical competency, resident wellness, and patient safety.

Methods

An anonymous online survey developed by the authors was sent to all Canadian plastic surgery residents and program directors. Basic summary statistics were calculated.

Results

Eighty (53%) residents and 10 (77%) program directors responded. Residents reported working an average of 73 hours in hospital per week with 8 call shifts per month and sleep 4.7 hours/night while on call. Most residents (88%) reported averaging 0 post-call days off per month and 61% will work post-call without any sleep. The majority want the option of working post-call (63%) and oppose an 80-hour weekly maximum (77%). Surgical and medical errors attributed to post-call fatigue were self-reported by 26% and 49% of residents, respectively. Residents and program directors expressed concern about the ability to master surgical skills without working post-call.

Conclusions

The majority of respondents oppose duty hour restrictions. The reason is likely multifactorial, including the desire of residents to meet perceived expectations and to master their surgical skills while supervised. If duty hour restrictions are aggressively implemented, many respondents feel that an increased duration of training may be necessary.

The fetal hypothalamus and pituitary in the initiation of labour

Evidence is presented for a number of events in the fetal hypothalamic-pituitary axis which may play a key role in the onset of labour: (1) In the sheep fetus a progressive rise in the fetal circulating concentrations of corticotropin in the days preceding delivery; (2) In the human fetus a switch from the production of corticotropin-like fragments (melanotropin and corticotropin-like intermediate lobe peptide) to authentic corticotropin in the last weeks of gestation; there is evidence also for a placental origin of corticotropin; (3) In the human fetus, a release of oxytocin and vasopressin associated with the process of spontaneous labour.

Highly abnormal maternal inhibin and beta-human chorionic gonadotropin levels along with severe HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome at 17 weeks' gestation with triploidy

A 17-week pregnancy complicated by severe hypertension is reported. The fetus had multiple anomalies and was found to have triploidy. Assay of maternal serum markers for trisomy 21 revealed elevated levels of inhibin (137.51 multiples of the median) and human chorionic gonadotropin (41.51 multiples of the median).

Prenatal diagnosis of nonmosaic trisomy 9 and related ultrasound findings at 11.7 weeks

Trisomy 9 is a relatively rare chromosomal abnormality. There have been no reports of first trimester ultrasound findings associated with mosaic or nonmosaic trisomy 9 in the literature. A case of nonmosaic trisomy 9 diagnosed prenatally with ultrasound findings at 11.7 weeks gestation is presented along with associated abnormal ultrasound findings.

Combined coronary artery bypass grafting and carotid endarterectomy

Combined carotid endarterectomy and coronary artery bypass grafting was performed in 52 patients between January 1982 and September 1994. Forty-nine patients had stable or unstable angina and three had symptom-free coronary artery disease detected by stress testing. Thirty-one patients had triple-vessel disease and 17 had left main trunk or left main equivalent coronary artery disease. Five patients had symptom-free carotid artery disease, 12 had non-specific neurological symptoms, and 35 had transient ischaemic attacks. Carotid endarterectomy was performed first, followed by coronary artery bypass grafting. There were three postoperative deaths, two cardiac and one neurological, for a mortality rate of 5.8%. One patient suffered a permanent neurological deficit (1.9%). It is concluded that combined carotid endarterectomy/coronary artery bypass grafting can be performed in selected patients with acceptable neurological morbidity, although cardiac mortality was not eliminated by the combined approach.

Surgical procedure for the cure of atrioventricular junctional ("AV node") reentrant tachycardia: anatomic and electrophysiologic effects of dissection of the anterior atrionodal connections in a canine model

OBJECTIVES

This study was undertaken to examine the electrophysiologic and anatomic effects of a surgical procedure that cures the anterior (common) type of atrioventricular (AV) junctional reentrant tachycardia.

BACKGROUND

The procedure was designed to interrupt the reentrant circuit at the point of earliest atrial activation during AV junctional reentrant tachycardia, the anterior atrionodal connections.

METHODS

Atrioventricular node function and the sequence of electrical excitation of Koch's triangle were examined in 18 dogs. Excitation of Koch's triangle was mapped using a 60-channel mapping system. Surgical dissection was performed in 10 dogs and a sham procedure in 8. After 28 to 35 days, AV node function and the atrial excitation pattern were reassessed. The AV junction was examined using light microscopy.

RESULTS

Some degree of AV node damage was visible in all dogs in the dissection group, but it was minor in 40% of cases. The anterior part of the AV node was disconnected from the anterior atrionodal connections in all cases. Anterograde AV node function was mildly impaired. The median AH interval was increased (62 vs. 76 ms [interquartile ranges 48 to 72 and 64 to 104, respectively], p = 0.05), and the AV Wenckebach cycle length was increased (210 vs. 245 ms [interquartile ranges 200 to 230 and 210 to 260, respectively], p = 0.02). The degree of impairment of conduction was directly proportional to the length of dissection (p < 0.05) but not to the degree of damage to the AV node. Ventriculoatrial (VA) conduction was destroyed in 50% of dogs undergoing dissection but in none of those with a sham operation (p < 0.04). The AV node remained responsive to autonomic blocking drugs, and atrial mapping during ventricular pacing revealed that the site of exit from the AV node had been altered.

CONCLUSIONS

The atrionodal connections closest to the His bundle are the preferred route of conduction through the AV node during normal AV or VA conduction. Destruction of these connections modifies AV node conduction. The surgical procedure selectively interrupts these connections, and this interruption is likely to be the mechanism of cure.

Combined coronary artery bypass grafting and abdominal aortic aneurysm repair

Fifteen patients of mean age 65 years underwent simultaneous coronary artery bypass grafting and abdominal aortic aneurysm repair between 1988 and 1992. Of these 13 had coexistent angina and two had symptomless coronary artery disease detected by preoperative dipyridamole thallium scanning or exercise stress testing. All patients had significant coronary artery disease on coronary angiography. Coronary artery bypass grafting was performed first, with a median number of grafts of 4, a median aortic cross-clamp time of 39 min and a median bypass time of 74 min. Abdominal aortic aneurysm repair followed with a median aortic clamp time of 66 min. Six straight and nine bifurcated grafts were inserted. The median total operating time was 395 min. All patients were managed postoperatively in the cardiothoracic intensive care unit with a median duration of 5 days. The median total hospitalization was 14 days. One patient died of non-cardiac causes; hence the mortality rate was 6.7%. The authors' experience suggests that combined coronary artery bypass grafting and abdominal aortic aneurysm repair is feasible in carefully selected patients.

Lymphomatous presentation of childhood acute lymphoblastic leukemia. A subgroup at high risk of early treatment failure

Multivariate analyses of the clinical course of 1537 children with acute lymphoblastic leukemia (ALL) identified a subgroup which experienced short remission duration and a high incidence of extramedullary relapse. The patients differed from other ALL patients by the presence at diagnosis of two or more of a constellation of clinical and laboratory features: organomegaly or mass disease, E-rosette positivity, hemoglobin level greater than 10 g/dl, leukocyte count greater than 50,000/microliters, male predominance, and older age. This type of presentation of ALL is referred to as the "lymphoma syndrome" (LS) since such patients exhibit a pattern of several clinical and laboratory features which were observed repeatedly but in differing combinations, and some of which clinically resemble lymphoma. A subsequent database from 2231 patients was analyzed. Patients with a mediastinal mass, massive splenomegaly, or massive adenopathy, alone or in combination, had a worse outcome when the patient also had either leukocytosis, E-rosette-positive lymphoblasts, or a normal or near normal hemoglobin (Hb) level at diagnosis. Similarly, the above three laboratory features alone or in combination did not predict less than 40% disease-free survival (DFS) unless they were accompanied by at least one of the clinical features of mass disease. When at least one clinical feature and at least one laboratory feature were present, the overall DFS was 36% 6 years after diagnosis versus 64% for all other patients. The association of these features with poor prognosis remained significant after adjusting for the level of leukocyte count at diagnosis, age at diagnosis, and sex of the patients. Patients with this recurrent syndrome of features do not represent a homogeneous biologic entity but they constitute a subgroup of patients with ALL having a high risk of treatment failure using current therapies, including failure to achieve remission, early relapse, and increased frequency of relapse in extramedullary sites. They deserve early recognition at diagnosis and selection of treatment strategies appropriate for very high risk ALL.

Biologic characteristics and treatment of acute nonlymphocytic leukemia in children. Report of the ANLL Strategy Group of the Childrens Cancer Study Group

Today approximately 75 per cent of children with ANLL can be induced into a complete remission and approximately 40 per cent will have an event-free survival for more than 3 years, irrespective of whether they received a bone marrow transplantation or chemotherapy after induction. In order to achieve these results very intensive therapy is required. The morbidity and mortality of treatment are high. The length of therapy needed after induction of remission is not known. Whether or not maintenance therapy is required is perhaps related most directly to the intensity of the therapy employed. Similarly, the role of bone marrow transplantation in patients in first remission, treatment of CNS leukemia, and treatment of chloromas are controversial. There is general agreement that WBCs over 100,000, acute monoblastic leukemia in infants less than 2 years of age, and certain chromosomal abnormalities are associated with a poor prognosis. Although there has been a dramatic improvement in the treatment of ANLL over the past 15 years, stratification of therapy based on biologic parameters, and alteration of treatment based on the early responses to treatment may be required before further advances will be made.

Experience with marrow harvesting from donors less than two years of age

Experience in harvesting marrow for allogeneic marrow transplantation from 23 infant donors is presented. Ten donors were less than one year of age and 13 were between one and two years of age at the time of initial donation. None of these donors experienced major difficulties following the aspiration procedure. Three donors had significant medical problems diagnosed during the pre-donation evaluation. All aspirations were performed from iliac crests and all donors were given general anesthesia. Irradiated blood bank transfusions were given to 85% of the donors during the procedure. The volume of marrow obtained ranged from 11.5 to 19.3 ml/kg donor weight and contained from 2.5 to 10.4 x 10(8) nucleated cells/kg donor weight. Thus, very young children may safely donate marrow for allogeneic transplantation and the nucleated cell count obtained is substantial.

Monitoring clinical research. A report from the Childrens Cancer Study Group

This report describes an evaluative approach in assessing study quality in clinical trials. The size of the data set required is defined using decision analysis methods. Assuming entry of eligible patients, the minimum data set required in determining study quality includes: the treatment agent, the protocol stipulated treatment time, and the actual time of administration. While toxicity, complication and response data are primary for the resolution of the scientific issues, they are secondary for study performance questions. Separation of study performance and scientific questions simplifies the design and execution of complex, multimodal, multidisciplinary clinical trials. Application of separate criteria for study performance and scientific questions enhances understanding of protocol requirements by data managers, physicians, and nurses. Once study performance issues are resolved, the scientific issues addressed by the protocol can be considered in detail. The usual practice of focusing on science and study performance simultaneously precludes efficient consideration of either data set. The distinction between analyses of study performance and of scientific questions is illustrated using data from Childrens Cancer Study Group protocol CCG-551. This study is a controlled trial of therapies for non-Hodgkin's lymphoma. The protocol provides an example of modern diagnostic and therapeutic management complexities.

Evaluation of cyclocytidine in reinduction and maintenance therapy of children with acute nonlymphocytic leukemia previously treated with cytosine arabinoside: a report from Children's Cancer Study Group

A study of children in relapse with acute nonlymphocytic leukemia (ANLL) previously maintained in remission with combination chemotherapy including cytosine arabinoside (Ara-C) was undertaken by Children's Cancer Study Group (CCSG) to assess the efficacy of cyclocytidine (Cyclo-C), a depot Ara-C, compared to parenteral Ara-C given every 12 hr. The reinduction protocol consisted of daunomycin combined with either Ara-C (Regimen 1) or Cyclo-C (Regimen 2). One-hundred thirty eligible patients were entered on the randomized study. Hematologic toxicity was significant in both regimens and resulted in four drug-related deaths. Cardiac toxicity was observed in five patients, manifested only by abnormal echocardiogram or electrocardiogram patterns in three and congestive heart failure in two patients. Seventy-seven of 112 evaluable patients achieved M-1 or M-2A marrow remissions (69%): 46 of 60 on Regimen 1 (75%), 30 of 52 on Regimen 2 (60%). The remission rate between the two regimens was not significantly different. There was no significant difference in the duration of remission comparing maintenance cyclophosphamide combined with Ara-C or with Cyclo-C. Addition of VP-16 and CCNU to the maintenance therapy did not prolong the duration of remission. This study indicates that patients with childhood ANLL previously treated with Ara-C and daunomycin can obtain a successful second remission. A single daily subcutaneous dose of Cyclo-C was found to be as efficacious as Ara-C given intravenously every 12 hr. The single dose schedule provides a convenient way to treat patients with relapsed ANLL in the outpatient setting.

Current status of the biology and treatment of acute non-lymphocytic leukemia in children (report from the ANLL strategy group of the Children's Cancer Study Group

Major advances have been made in the past 10 yr in both the understanding of the biologic characteristics of acute nonlymphocytic leukemia and in the treatment of patients with this disease. Advances in the biologic characteristics include: a better understanding of the nature of leukemic cell proliferation and differentiation; a clearer description of the morphological, histochemical, and ultrastructural characteristics of leukemic cells; a recognition that a high percentage of patients may have specific cytogenetic abnormalities; and a recognition that biochemical differences exist between acute nonlymphocytic leukemia (ANLL) and acute lymphoblastic leukemia (ALL). Today, over 70% of children with ANLL can be induced into a complete remission and over 25% are remaining in a continuous remission for over 2 yr. In spite of these improved results, the best method of extending remissions is unknown. It is unlikely that better results of therapy will be achieved in the future by tailoring the treatment according to the biologic characteristics of the patient, since it appears that ANLL is a heterogeneous group of diseases.

Comparison of the therapeutic response of patients with childhood acute lymphoblastic leukemia in relapse to vindesine versus vincristine in combination with prednisone and L-asparaginase: a phase III trial

One hundred and seventy-nine previously treated children with acute lymphoblastic leukemia in relapse considered not "resistant" to vincristine (VCR) were randomly allocated to receive reinduction therapy with either vindesine (VND) or VCR, in combination with prednisone and L-asparaginase. Complete remission rates were 57% for both regimens and were significantly greater for first relapsers (69%) than for subsequent relapsers (43%). No significant difference in response rates by regimen was observed within relapse groups. Patients treated with VND experienced significantly greater hematologic toxicity. These data suggest that there is no advantage to using VND instead of VCR in standard reinduction therapy for childhood acute lymphoblastic leukemia in relapse.

Do infants with stage IV-S neuroblastoma need treatment?

The study reports the results of treatment in 31 infants under age 12 months with stage IV-S neuroblastoma diagnosed between 1976 and 1979. All had small or undetected primary tumours associated with disease in one or more of the following sites: liver, skin, or marrow. The primary site was left adrenal (in 16), and other areas included paravertebral, mediastinum, and pelvis (in 5); in 3 the primary site could not be found. Distant disease was found in the liver (in 29), marrow (in 16), and skin (in 8). Other sites affected were pancreas, pleura, peritoneum, and regional nodes. Treatment varied according to the clinical course of the disease; most patients had very little. In 19 primary tumour was resected, in 21 the liver was irradiated with a median dose of 450 rad, and 15 received chemotherapy in courses varying between 1 month and 1 year. Nine patients had resection of the primary tumour as their only treatment and all survive; a total of 16 patients had sites of disease which regressed spontaneously. Four of 31 patients died in the first 2 months despite vigorous measures, all from some complication of the disease or its treatment. The projected 2-year survival rate is 87%. Children with this 'special' pattern of widespread neuroblastoma fare well with little or no treatment unless early complications develop. In this study none died of late progression of their disease.

Haemoglobin M Hyde Park occurring as a fresh mutation: diagnostic, structural, and genetic considerations

Hb M Hyde Park disease was detected in a girl who for several years was thought to have cyanotic heart disease. The problems of recognizing the condition are outlined and clues to diagnosis are discussed. Evidence for heme loss from the aberrant beta chains of Hb M Hyde Park and production of an unstable molecule is presented. The normal haematological findings in the patient's parents, as well as their blood groups and isozymes, suggest that the occurrence of her Hb M Hyde Park was the result of a fresh mutation.