Identification of TLR2 Signalling Mechanisms Which Contribute to Barrett's and Oesophageal Adenocarcinoma Disease Progression

Simple Summary

Oesophageal adenocarcinoma (EAC) is a common type of oesophageal cancer with a rapidly rising incidence. Risk factors such as reflux, smoking, obesity and Barrett’s oesophagus cause chronic irritation and inflammation in the oesophagus. A receptor that causes inflammation, called Toll-like receptor 2 (TLR2), is expressed at higher levels in oesophageal cells from patients with Barrett’s and EAC, compared to disease-free patients. This study aimed to identify mechanisms involved in TLR2-mediated inflammation in oesophageal cells; and to assess whether TLR2 represents a therapeutic target to limit EAC development. Findings reveal that TLR2 activation in Barrett’s organoids and oesophageal cancer cells amplifies inflammation and promotes cancer development by causing the secretion of several inflammatory factors, most notably the nuclear protein, HMGB1. We demonstrate that TLR2 neutralisation efficiently blocks the inflammatory effects of TLR2 in these systems, revealing the therapeutic potential of TLR2 targeting to limit oesophageal disease and cancer progression.

Abstract

Chronic inflammation plays an important role in the pathogenesis of oesophageal adenocarcinoma (EAC) and its only known precursor, Barrett’s oesophagus (BE). Recent studies have shown that oesophageal TLR2 levels increase from normal epithelium towards EAC. TLR2 signalling is therefore likely to be important during EAC development and progression, which requires an inflammatory microenvironment. Here, we show that, in response to TLR2 stimulation, BE organoids and early-stage EAC cells secrete pro-inflammatory cytokines and chemokines which recruit macrophages to the tumour site. Factors secreted from TLR2-stimulated EAC cells are shown to subsequently activate TLR2 on naïve macrophages, priming them for inflammasome activation and inducing their differentiation to an M2/TAM-like phenotype. We identify the endogenous TLR2 ligand, HMGB1, as the factor secreted from EAC cells responsible for the observed TLR2-mediated effects on macrophages. Our results indicate that HMGB1 signalling between EAC cells and macrophages creates an inflammatory tumour microenvironment to facilitate EAC progression. In addition to identifying HMGB1 as a potential target for early-stage EAC treatment, our data suggest that blocking TLR2 signalling represents a mechanism to limit HMGB1 release, inflammatory cell infiltration and inflammation during EAC progression.

Characterizing caspase-1 involvement during esophageal disease progression

Barrett's esophagus (BE) is an inflammatory condition and a neoplastic precursor to esophageal adenocarcinoma (EAC). Inflammasome signaling, which contributes to acute and chronic inflammation, results in caspase-1 activation leading to the secretion of IL-1β and IL-18, and inflammatory cell death (pyroptosis). This study aimed to characterize caspase-1 expression, and its functional importance, during disease progression to BE and EAC. Three models of disease progression (Normal-BE-EAC) were employed to profile caspase-1 expression: (1) a human esophageal cell line model; (2) a murine model of BE; and (3) resected tissue from BE-associated EAC patients. BE patient biopsies and murine BE organoids were cultured ex vivo in the presence of a caspase-1 inhibitor, to determine the importance of caspase-1 for inflammatory cytokine and chemokine secretion.Epithelial caspase-1 expression levels were significantly enhanced in BE (p < 0.01). In contrast, stromal caspase-1 levels correlated with histological inflammation scores during disease progression (p < 0.05). Elevated secretion of IL-1β from BE explanted tissue, compared to adjacent normal tissue (p < 0.01), confirmed enhanced activity of caspase-1 in BE tissue. Caspase-1 inhibition in LPS-stimulated murine BE organoids caused a significant reduction in IL-1β (p < 0.01) and CXCL1 (p < 0.05) secretion, confirming the importance of caspase-1 in the production of cytokines and chemokines associated with disease progression from BE to EAC. Targeting caspase-1 activity in BE patients should therefore be tested as a novel strategy to prevent inflammatory complications associated with disease progression.

Caspase-11 regulates the tumour suppressor function of STAT1 in a murine model of colitis-associated carcinogenesis

Murine inflammatory caspase-11 has an important role in intestinal epithelial inflammation and barrier function. Activation of the non-canonical inflammasome, mediated by caspase-11, serves as a regulatory pathway for the production of the pro-inflammatory cytokines IL-1β and IL-18, and has a key role in pyroptotic cell death. We have previously demonstrated a protective role for caspase-11 during dextran sulphate sodium (DSS)-induced colitis, however the importance of caspase-11 during colorectal tumour development remains unclear. Here, we show that Casp11^−/− mice are highly susceptible to the azoxymethane (AOM)-DSS model of colitis-associated cancer (CAC), compared to their wild type (WT) littermates. We show that deficient IL-18 production occurs at initial inflammation stages of disease, and that IL-1β production is more significantly impaired in Casp11^−/− colons during established CAC. We identify defective STAT1 activation in Casp11^−/− colons during disease progression, and show that IL-1β signalling induces caspase-11 expression and STAT1 activation in primary murine macrophages and intestinal epithelial cells. These findings uncover an anti-tumour role for the caspase-11 and the non-canonical inflammasome during CAC, and suggest a critical role for caspase-11, linking IL-1β and STAT1 signalling pathways.

BigWig and BigBed: enabling browsing of large distributed datasets

Summary: BigWig and BigBed files are compressed binary indexed files containing data at several resolutions that allow the high-performance display of next-generation sequencing experiment results in the UCSC Genome Browser. The visualization is implemented using a multi-layered software approach that takes advantage of specific capabilities of web-based protocols and Linux and UNIX operating systems files, R trees and various indexing and compression tricks. As a result, only the data needed to support the current browser view is transmitted rather than the entire file, enabling fast remote access to large distributed data sets.

Availability and implementation: Binaries for the BigWig and BigBed creation and parsing utilities may be downloaded at http://hgdownload.cse.ucsc.edu/admin/exe/linux.x86_64/. Source code for the creation and visualization software is freely available for non-commercial use at http://hgdownload.cse.ucsc.edu/admin/jksrc.zip, implemented in C and supported on Linux. The UCSC Genome Browser is available at http://genome.ucsc.edu

Contact:ann@soe.ucsc.edu

Supplementary information: Supplementary byte-level details of the BigWig and BigBed file formats are available at Bioinformatics online. For an in-depth description of UCSC data file formats and custom tracks, see http://genome.ucsc.edu/FAQ/FAQformat.html and http://genome.ucsc.edu/goldenPath/help/hgTracksHelp.html

Inspired supplemental oxygen reduces markers of oxidative stress during elective colon surgery

Oxygen reduces postoperative markers of oxidative stress

Design and baseline characteristics for the ACE Inhibitor After Anthracycline (AAA) study of cardiac dysfunction in long-term pediatric cancer survivors

PURPOSE

The ACE Inhibitor After Anthracycline (AAA) study is a randomized, double-blind, controlled clinical trial comparing enalapril with placebo to determine whether treatment can slow the progression of cardiac decline in patients who screen positive for anthracycline cardiotoxicity.

METHODS

The primary outcome measure is the rate of decline, over time, in maximal cardiac index (in liters per minute per meters squared) at peak exercise; the secondary outcome measure is the rate of increase in left ventricular end systolic wall stress (in grams per centimeters squared). Patients >2 years off therapy and <4 years from diagnosis, aged 8 years and older, were eligible if they had received anthracyclines and had at least one cardiac abnormality identified at any time after anthracycline exposure.

RESULTS

A total of 135 patients were randomized to enalapril or placebo. Baseline characteristics were similar across treatment groups.

CONCLUSIONS

The AAA study will provide important information concerning the efficacy of using angiotensin-converting enzyme inhibitors to offset the effects of late anthracycline cardiotoxicity.

The effects of dental wear on third molar eruption and on the curve of Spee in human archaeological dentitions

The abrasiveness of food is a key determinant in the rate of physiological attrition (dental wear) in humans. With increasing food processing through time, the rate of physiological dental wear in human teeth has decreased markedly. Many consider such wear to be beneficial to oral health and that insufficient wear may result in impaction of the third molars. If enhanced extraoral food processing provides an evolutionary advantage, then it is possible that agenesis of the redundant third molar may follow. One of the aims here was to examine impaction and agenesis of the third molars in four populations of varying antiquity and hence varying dental-wear rates. Paradoxically, whilst there is a decrease in the rate of dental wear with modernity, there is also an increasing prevalence of advanced dental wear due to prolongation of the lifespan of the human dentition. As the effect of dental wear on the curve of Spee was unknown, a second aim was to examine it in an archaeological population with a high rate of dental wear. The results showed an increase in non-eruption and impaction of the third molars with modernity, but did not demonstrate a significant increase in the rate of agenesis. The time period over which impaction and agenesis could be discerned was of the order of 600 years and this may not be sufficient to observe adaptive changes at the genetic level in humans. In molar teeth there was no clear indication of maintenance of the curve of Spee with dental wear. This has potential implications on the design of prostheses for the worn dentition.

Cytokine production during in vitro hemodialysis with new and formaldehyde- or renalin-reprocessed cellulose dialyzers

Critics of reuse have suggested that patients treated with reprocessed dialyzers are exposed to pyrogen trapped from the water or solutions used during the reprocessing cycle, thereby triggering the synthesis and release of proinflammatory cytokines, resulting in cachexia. To test this hypothesis, the production of interleukin (IL)-1 alpha by peripheral blood mononuclear cells (PBMC) during in vitro dialysis with new or reprocessed cellulose dialyzers was compared. An in vitro closed-loop dialysis circuit was created with standard hemodialysis blood lines and either new cellulose dialyzers or dialyzers reprocessed 10 times with either formaldehyde/bleach (formaldehyde) or peracetic acid/hydrogen peroxide mixture (Renalin). The circuit was rinsed with 2 L or more of pyrogen-free normal saline before the start of in vitro dialysis until the blood compartment tested negative for residual formaldehyde/Renalin. Heparinized whole blood from healthy volunteers was circulated for 3 h in the blood compartment at 100 mL/min at 37 degrees C. The dialysate compartment was sealed. Peripheral blood mononuclear cells (PBMC) were harvested from the blood compartment before and at the end of 3 h of in vitro dialysis. Total IL-1 alpha synthesis (cell associated plus secreted) by unstimulated and endotoxin-stimulated PBMC was measured by a specific, non-cross-reactive radioimmunoassay. After 3 h of in vitro dialysis, IL-1 alpha production (in picograms per 2.5 million PBMC) by unstimulated PBMC increased from 354 +/- 63 at baseline to 454 +/- 57 with new dialyzers (P = 0.25), from 453 +/- 101 to 450 +/- 67 with formaldehyde-reprocessed dialyzers (P = 0.98), and from 360 +/- 61 to 538 +/- 144 with Renalin-reprocessed dialyzers (P = 0.23). IL-1 alpha production by endotoxin-stimulated PBMC increased from 5,214 +/- 996 to 9,237 +/- 929 with new dialyzers (P < = 0.001), from 6,395 +/- 955 to 9,636 +/- 1,058 with formaldehyde-reprocessed dialyzers (P = 0.006), and from 7,561 +/- 1,000 to 10,092 +/- 2,470 with Renalin-reprocessed dialyzers (P = 0.32). However, there were no significant differences among groups with respect to IL-1 alpha production by unstimulated or endotoxin-stimulated PBMC either before or after 3 h of in vitro dialysis. These data argue against the suggestion that exposure to reprocessed dialyzers results in enhanced synthesis of proinflammatory cytokines. In fact, reprocessed dialyzers probably induce less cytokine production than do new cellulose dialyzers.

Time to put the world on the curriculum

A postal survey of 66 heads of midwifery education in England, and detailed personal interviews with four midwives with particular expertise in this area, showed that: International issues have a place in midwifery education programmes. Curricula are being developed to reflect this. Resources should be shared, and interested midwives brought together.

A novel translational regulation function for the simian virus 40 large-T antigen gene

Cells use the interferon-induced, double-stranded-RNA-dependent protein kinase PKR as a defense against virus infections. Upon activation, PKR phosphorylates and thereby inactivates the protein synthesis initiation factor eIF-2, resulting in the cessation of protein synthesis. Viruses have evolved various strategies to counteract this cellular defense. In this paper, we show that simian virus 40 (SV40) large-T antigen can antagonize the translational inhibitory effect resulting from the activation of PKR in virus-infected cells. Unlike the situation with other virus-host cell interactions, SV40 large-T antigen does not block the activation of PKR, suggesting that SV40 counteracts the cellular antiviral response mediated by PKR at a step downstream of PKR activation. Mutational analysis of large-T antigen indicates that a domain located between amino acids 400 and 600 of large-T antigen is responsible for this function. These results define a novel translational regulatory function for the SV40 large-T antigen.

Infected abdominal aortic grafts

Aortic grafts were inserted in 1711 patients at Ottawa Civic Hospital (OCH) between 1976 and 1986. Aorto-iliac occlusive disease was the indication in 884 while in 827, the graft was inserted for abdominal aortic aneurysms. Graft infection occurred in 12 patients; six presenting with gastrointestinal bleeding due to aorto-enteric fistula (AEF) and the other six presenting with groin abscesses, mostly as a draining sinus. These were treated with graft excision and immediate extra-anatomic bypass. Seven patients died, giving a mortality rate of 58%. Three surviving patients required above-knee amputatio. These results are comparable to the results of others in the literature; therefore, continuing assessment of all aspects of graft infection and the search for more effective methods of prevention and management are needed.

Comparison of cardiac function tests after anthracycline therapy in childhood. Implications for screening

BACKGROUND

Numerous methods for evaluating cardiac function after cardiotoxic therapy have been suggested. A practical algorithm for screening a large patient population is needed.

METHODS

Seventy-three patients (median age, 15.3 years [range, 9-29 years) who received anthracyclines (median dose, 300 mg/m2 [range, 50-750 mg/m2) for a childhood malignancy underwent a battery of commonly used tests of cardiac function: (1) echocardiographic shortening fraction (ESF); (2) resting and exercise radionuclide scan (multiple gaited acquisition [MUGA]); (3) electrocardiogram (ECG); (4) 24-hour Holter monitor, and (5) questionnaire concerning exercise tolerance.

RESULTS

Patients with an abnormal resting ejection fraction on MUGA were more likely to have an abnormal ESF (P = 0.023), prolongation of the QTc interval (P = 0.014), and complaints of "difficulty" with exercise (P = 0.04). An abnormal results for a resting study was not predictive of an abnormal MUGA exercise response. There was no association between the presence of significant dysrhythmia on Holter monitor and any resting test. An algorithm was developed using a normal ESF and QTc interval, and a negative history of exercise intolerance to identify patients who need not undergo a MUGA. With the use of such an algorithm, 29 of the 73 patients would not have undergone the MUGA, only 2 of whom had an abnormal resting ejection fraction.

CONCLUSION

Patients at risk for cardiac damage after cancer therapy who have normal ESF and QTc interval results and no history of exercise intolerance are unlikely to have abnormal MUGA results. Significant dysrhythmia may be present in the absence of other abnormalities.

Cardiac dysfunction following spinal irradiation during childhood

PURPOSE

Although spinal irradiation used in the treatment of CNS malignancies includes a portion of the heart in the radiation field, cardiac effects have not been previously reported.

PATIENTS AND METHODS

We compared patients treated for malignancy in childhood with spinal irradiation (n = 26) with patients treated with mediastinal/flank irradiation (n = 47) that included the heart in the radiation field. All patients were more than 1 year from completion of radiation therapy. Patients underwent at least two of the following cardiac evaluations: (1) ECG; (2) 24-hour ambulatory ECG; (3) echocardiogram; and (4) exercise-testing using cycle ergometry.

RESULTS

Twelve of 16 patients (75%) in the spinal irradiation group with an assessable exercise test achieved a maximal cardiac index (MCI) below the fifth percentile as compared with 13 of 40 patients (32%) who had received mediastinal/flank irradiation (P = .007). Furthermore, after adjusting for normal heart growth, radiation and anthracycline doses, and follow-up time, the group of patients who received spinal irradiation had significantly higher estimated posterior wall stress (P = .002), expressed as the natural logarithm of the ratio of end-diastolic left ventricular internal diameter (LVID) to left ventricular posterior wall thickness (LVPWT), than the group who had received mediastinal/flank irradiation. Finally, eight of 26 patients (31%) in the spinal group had pathologic Q-waves in the inferior leads versus three of 47 (6.4%) in the mediastinal/flank group (P = .001).

CONCLUSION

Patients who have received spinal irradiation for pediatric malignancies appear to be at risk for significant cardiac dysfunction. The asymmetric distribution of radiation to a growing heart, as given with spinal irradiation, may be the cause of these findings.

Genotoxic activity of 1-chloromethylpyrene in stomach epithelium in vivo: insensitivity of the stomach scintillation UDS assay

An acknowledged weakness of current testing programmes for genotoxic hazard has been the potential insensitivity of the established mouse bone marrow micronucleus test and rat liver unscheduled DNA synthesis (UDS) assays to direct-acting or short-lived mutagens, which may be consumed at the site of initial contact. In such cases, in vivo test systems sampling tissues such as the skin or the stomach would provide valuable data. To test these principles a stomach UDS assay was evaluated using the potent locally active mutagen 1-chloromethylpyrene (1-CMP). Contrary to expectations, no UDS response was observed 16 h following 1-CMP dosage by oral gavage. To confirm the integrity of the 1-CMP used for the stomach UDS assay, a sample of the stored chemical was re-evaluated in vitro and shown to be still strongly positive in the Ames assay and to have alkylating activity at least 15 min after incubation at stomach acid pH. No UDS response was observed when test dose levels were reduced or when earlier sampling times were used. Other genotoxic endpoints were examined in stomach. 32P-Postlabelling analysis revealed high levels of adduct formation in gastric DNA. An assay utilizing electrophoresis of DNA (the comet assay) showed the occurrence of DNA damage following dosing with 1-CMP in vivo. These positive results confirmed that 1-CMP should be regarded as a potential in vivo genotoxin. The failure to detect a UDS response to 1-CMP in stomach was investigated; a strong UDS response was observed in an in vitro hepatocyte UDS assay of 1-CMP indicating that the rat was capable of repairing 1-CMP-derived DNA adducts. Pretreatment of rats with hydroxyurea depressed the level of incorporation of thymidine into DNA both in negative and positive [methyl-N-nitrosoguanidine (MNNG)] controls. The results of these studies indicated that the protease digestion method employed did not selectively or efficiently sample those cells with any UDS response to 1-CMP or MNNG, and the activity seen for the latter was most likely due to the presence of S phase cells within the digests. As a result of the finding that UDS responses were not demonstrated for the potent direct-acting mutagens 1-CMP and MNNG, the protease digestion/scintillation method for stomach UDS does not appear to have general value in a screening programme for locally active genotoxic agents.

Electrocardiographic changes and arrhythmias after cancer therapy in children and young adults

Transient electrocardiographic changes and arrhythmias are known to be acute manifestations of cardiotoxicity secondary to cancer therapy with anthracyclines or cardiac irradiation. However, despite the known risk of late cardiac dysfunction in survivors of childhood cancer therapy, the risk of clinically important electrocardiographic abnormalities and arrhythmias after treatment is unknown. Standard 12-lead and 24-hour ambulatory electrocardiograms were recorded in 73 patients who received anthracyclines alone, 24 who received cardiac irradiation alone, and 27 who received both anthracyclines and cardiac irradiation. The mean age of the patients was 15 years. Mean cumulative anthracycline dose was 282 mg/m2 in patients who received anthracyclines alone and 244 mg/m2 in patients who received both anthracyclines and cardiac irradiation. Analysis of the 12-lead and 24-hour electrocardiograms demonstrated increased frequency of QTc prolongation, supraventricular premature complexes, supraventricular tachycardia, ventricular premature complexes, couplets and ventricular tachycardia (all p less than 0.001) when compared with an age-matched healthy population. Most patients had abnormalities limited to single supraventricular or ventricular premature complexes; however, potentially serious ventricular ectopy, including ventricular pairs and ventricular tachycardia, were noted in patients with cumulative doses greater than 200 mg/m2. Electrocardiographic abnormalities and arrhythmias are not limited to the acute phase of treatment with anthracyclines and cardiac irradiation. Survivors of childhood malignancy who received anthracyclines or cardiac irradiation, or both, probably should undergo ambulatory electrocardiographic monitoring as part of their follow-up to detect potentially life-threatening arrhythmias.

Exercise assessment of cardiac function in children and young adults before and after bone marrow transplantation

Cardiac toxicity is a potential complication of bone marrow transplantation because recipients frequently receive cardiotoxic chemotherapy and/or irradiation before transplantation. Most studies indicate that transient cardiac toxicity occurs within weeks of transplantation, but few studies have evaluated either cardiac status before or late after transplantation. Cardiac performance was assessed via cycle ergometry in 20 children and young adults before transplantation and 31 other children and young adults after transplantation. Mean survival time in the group post-transplantation was 3.9 years with a range of 11 months to 12.1 years. Left ventricular size and shortening fraction at rest were assessed via echocardiography. Data were compared to those of 70 healthy subjects from our laboratory. Patients before and after transplantation had normal oxygen consumptions and cardiac indices at rest. During exercise, however, patients treated for cancer both before and after bone marrow transplantation had reduced exercise times, reduced maximal oxygen consumptions, and reduced ventilatory anaerobic thresholds. Cardiac reserve, as judged by the response of the cardiac output during exercise, was reduced severely. There were no significant differences between the groups tested before and after transplantation. Patients who had been treated for aplastic anemia, who had received less intensive therapy before transplantation, performed significantly better than did patients treated for cancer. Despite these findings, only four patients had abnormalities by echocardiography. In conclusion, before transplantation patients with oncologic diagnoses had serious limitations in exercise performance, most likely as a result of the effects of the cardiotoxic therapy given as part of their conventional cancer therapy. Long-term survivors of bone marrow transplantation also had similar abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoplastic left heart syndrome: hemodynamic and angiographic assessment after initial reconstructive surgery and relevance to modified Fontan procedure

After undergoing initial reconstructive surgery for hypoplastic left heart syndrome performed between August 1985 and March 1989, 59 patients (age range 3 to 27 months, mean 13.8 +/- 4.5) underwent elective cardiac catheterization in anticipation of a modified Fontan procedure. Five important hemodynamic and anatomic features considered to be components of successful reconstructive surgery were specifically addressed. 1) Interatrial communication: Only two patients had a measured pressure difference of greater than 4 mm Hg across the atrial septum. 2) Tricuspid valve function: Angiography demonstrated significant tricuspid valve regurgitation in only five patients (moderate in two and severe in three). 3) Aortic arch: Pressure tracings from the right ventricle to the descending aorta revealed a gradient greater than 25 mm Hg in only two patients. 4) Pulmonary vasculature: Ten patients had a calculated pulmonary vascular resistance greater than 4 U.m2; 51 (86%) of the 59 patients had no evidence of distortion (stenosis or hypoplasia) of either the left or the right pulmonary artery. 5) Right ventricular function: Five patients had an end-diastolic pressure in the right ventricle greater than 12 mm Hg and two patients had qualitative assessment of decreased ventricular function. Comparison of catheterization data between survivors and nonsurvivors of the subsequent modified Fontan procedure showed that only significant tricuspid regurgitation is a possible predictor of poor outcome. After first stage reconstructive surgery for hypoplastic left heart syndrome, most survivors have favorable anatomy and hemodynamics at follow-up cardiac catheterization for a subsequent Fontan procedure.

Pediatric exercise testing

The number of diagnostic modalities available to the pediatric cardiologist continues to escalate. However, with so many choices, it is often difficult to know what test is most efficacious in a given situation or how often to repeat it. This review summarizes the data from several exercise studies published within the past year. These studies address exercise as a diagnostic modality in children and adults with and without heart disease and compare exercise testing with other diagnostic modalities. They demonstrate some of the variables that should be routinely assessed during an exercise test, and they introduce many avenues for continued research.

Hypoplastic left heart syndrome. Outcome after initial reconstruction and before modified Fontan procedure

The outcome and clinical course before modified Fontan procedure were reviewed for 200 patients with hypoplastic left heart syndrome who underwent initial reconstructive surgery between August 1985 and March 1989. The median age at the time of initial reconstruction was 6 days (range, 1 day to 7.2 months). In 28 patients, a right modified Blalock-Taussig shunt was used; in 172 patients, a central shunt was placed. Additional procedures (n = 41) performed in 38 patients (median age, 5 months; range, 6 days to 17.5 months) were revision of systemic-to-pulmonary shunt (n = 15), arch reconstruction (n = 8), balloon angioplasty of arch obstruction (n = 7), atrial septectomy (n = 4), pulmonary artery angioplasty (n = 2), tricuspid valve annuloplasty or replacement (n = 4), and modified Glenn shunt (n = 1). There was no significant difference in the frequency of additional procedures performed more than 30 postoperative days in the survivors compared with the nonsurvivors. Actuarial survival rates were 0.66 (1 month), 0.48 (12 months), and 0.44 (18 months). Seventy percent of all deaths occurred during the initial admission, with 32% resulting from acute cardiovascular collapse during the first postoperative day. There was no statistical difference in actuarial survival when assessed by the type of shunt used or by anatomical subtype or when the influence of additional interventions was considered. Substantial improvement in outcome may be possible if immediate perioperative mortality can be reduced. We speculate that some of the intermediate mortality (30 days to 1 year) may be related to the effects of chronic exposure of the right ventricle to volume overload at systemic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective detection by Doppler color flow imaging of additional defects in infants with a large ventricular septal defect

The use of Doppler color flow imaging and axial contrast angiography in the preoperative detection of additional ventricular septal defects (in the setting of a known large defect) were compared in a prospective fashion. One hundred seventy-nine infants with two ventricles (each of at least normal size) and a large, nonrestrictive ventricular septal defect underwent reparative surgery before 2 years of age. The reference standard for the presence of additional defects was intraoperative verification or (in cases in which the surgeon did not visualize any additional defect) subsequent identification at postoperative angiography, postoperative color Doppler examination or reoperation. Only six patients (3%) had additional ventricular septal defects confirmed at the time of repair; an additional five (3%) had defects found only postoperatively. The negative predictive value of Doppler color flow imaging and angiography was 0.95 (168 of 176) and 0.97 (168 of 174), respectively. The sensitivity was 0.27 (3 of 11) and 0.45 (5 of 11), respectively. For certain malformations with a very low prevalence of additional muscular defects (such as perimembranous ventricular septal defect with normally aligned great arteries), a clinical trial of reparative surgery without prior invasive study appears reasonable.

Inflammatory aneurysms of the abdominal aorta

The treatment of inflammatory aneurysms of the abdominal aorta presents a formidable challenge to the surgeon. The retroperitoneal inflammatory reaction obliterates normal tissue planes, limiting access to the infrarenal aorta. During a 70-month period 25 (6%) of 439 patients operated on for abdominal aortic aneurysms were found to have the inflammatory type. These patients were more likely to be symptomatic than patients with noninflammatory aneurysms and they were more likely to be male. Although surgical repair of the aneurysms required longer aortic occlusion time and more blood replacement, the outcome was similar to that for patients treated for noninflammatory aneurysms.

Subcostal two-dimensional echocardiographic identification of anomalous attachment of septum primum in patients with left atrioventricular valve underdevelopment

Five variations of atrial septal morphology occur in hypoplastic left heart syndrome. One variety, termed anomalous attachment of septum primum, has been described only in necropsy series. Two-dimensional echocardiography was utilized to determine the incidence of this anomaly in patients with left atrioventricular (AV) valve underdevelopment, including those with other ventriculoarterial alignments, such as transposition of the great arteries. Forty-eight (37%) of 129 patients with normally aligned great arteries (and two ventricles) had anomalous attachment of septum primum. Ten (34%) of 29 patients with double outlet right ventricle and left AV valve underdevelopment had this anomaly. Four (50%) of eight patients with single ventricle exhibited this atrial septal variant. The most reliable view to identify anomalous attachment was the subcostal left oblique-equivalent cut. Recognition of atrial septal morphology has implications for preoperative and intraoperative management of patients with left AV valve underdevelopment. The similar prevalence of this atrial septal variant in patients with normally aligned great arteries, double outlet right ventricle and transposed great arteries suggests that there may be a common mechanism for left AV valve underdevelopment that is independent of the development of the arterial portion of the heart.

Pulmonary artery configuration after palliative operations for hypoplastic left heart syndrome

Pulmonary artery architecture and symmetry after palliative operations for hypoplastic left heart syndrome may affect subsequent suitability for a modified Fontan operation. Two-dimensional echocardiography was used to measure pulmonary artery diameter and assess symmetry after two types of systemic-pulmonary artery shunts: modified right Blalock-Taussig shunt (14 patients) and central shunt (from underside of aortic arch gusset to pulmonary artery confluence) (14 patients). Age, weight, preoperative diameter of right and left pulmonary arteries (proximal, middle, and distal segments), and mean interval between preoperative and postoperative echocardiographic studies (20.2 +/- 4.4 days in the Blalock shunt group; 19.1 +/- 6.8 days in the central shunt group) were similar. Early postoperatively, patients with a Blalock shunt showed a significant decrease in the diameter of all pulmonary artery segments except the distal right pulmonary artery. The diameters tapered from distal right to distal left pulmonary artery in this group. Patients with the central shunt had a significant decrease in the diameter of all pulmonary artery segments. There were no significant differences when cross comparisons were made of the various pulmonary arterial segments in patients after a central shunt. Similar findings persisted in 19 patients from both groups who had a late postoperative echocardiogram (mean interval between studies = 271 days in the group of 10 patients with Blalock shunt and 167 days in the group of nine patients with a central shunt). In conclusion, the central shunt preserves pulmonary artery symmetry, which may be important in candidates for the Fontan operation in infancy.

Two-dimensional and Doppler echocardiographic assessment of neonatal arterial repair for transposition of the great arteries

The arterial switch procedure has become an accepted reparative technique for transposition of the great arteries with or without ventricular septal defect. In this study the accuracy of prospective noninvasive imaging in detecting arterial tract obstruction and the prevalence and severity of arterial valvular regurgitation (as assessed by Doppler ultrasound) were evaluated in survivors of arterial repair. All 53 study patients underwent two-dimensional echocardiographic examination 2 days to 20 months (median 7 months) postoperatively; 43 patients also had pulsed and continuous wave Doppler studies. The accuracy of the noninvasive evaluation of arterial tract obstruction was determined by comparison of Doppler maximal instantaneous gradients with peak to peak gradients at nonsimultaneous catheterization in 26 patients. Twenty-one (81%) of the 26 patients underwent catheterization and successful pulsed and continuous wave Doppler examination of the right heart; 17 (81%) of these 21 had a maximal pressure gradient within 20 mm Hg of the peak to peak gradient obtained at catheterization. Echocardiographic identification of the stenotic site was correct in all eight of the patients in this group requiring reoperation. Twenty-three (88%) of the 26 patients who underwent catheterization had successful Doppler interrogation of the aortic tract; 22 (96%) of these 23 had a maximal instantaneous gradient within 20 mm Hg of the peak to peak catheterization gradient. Fourteen (32%) of 43 patients had mild or moderate pulmonary regurgitation by Doppler study. Three (7%) of the 43 had mild aortic regurgitation.

Hypoplastic left heart syndrome: lack of correlation between preoperative demographic and laboratory findings and survival following palliative surgery

To determine whether preoperative demographic and metabolic variables correlated with early or late survival following palliative surgery for hypoplastic left heart syndrome, we reviewed the charts of 89 patients operated upon from October 1984 to January 1987. The variables analyzed were age at operation, lowest preoperative pH and H2CO3, highest preoperative arterial oxygen saturation, the occurrence of a preoperative cardiorespiratory arrest, and location of birth relative to the surgical institution. The data were evaluated by chi-squared, multivariate, and life-table analyses to the end of the first postoperative year. None of the factors analyzed significantly correlated with either short-term (less than or equal to 30 days) or long-term (greater than 30 days) survival. Thus, neither demographic nor metabolic factors including prior cardiorespiratory arrest should be considered contraindications to surgical palliation for hypoplastic left heart syndrome.

The significance of tricuspid regurgitation in hypoplastic left-heart syndrome

Palliation of hypoplastic left-heart syndrome involves use of the morphologic right ventricle as the systemic ventricle and the tricuspid valve (in cases of mitral atresia/stenosis) or the common atrioventricular valve (in cases of malaligned atrioventricular canal) as the systemic atrioventricular valve. To determine the relationship between tricuspid or common atrioventricular valve function and the ultimate outcome of palliative surgery, 100 patients with hypoplastic left-heart syndrome were evaluated preoperatively by Doppler echocardiography to determine the degree of tricuspid regurgitation. These patients were then followed serially to assess changes with time in the functional status of the tricuspid or common atrioventricular valve and to determine the correlation of tricuspid or common atrioventricular valve regurgitation with survival. We discovered that tricuspid or common atrioventricular valve regurgitation is common in hypoplastic left-heart syndrome. Thirty-seven percent of the patients had mild, 13% had moderate, and 3% had severe tricuspid or common atrioventricular valve regurgitation on their preoperative Doppler echocardiograms. Throughout the first 2 postoperative years most patients had no significant change in the degree of tricuspid or common atrioventricular valve regurgitation when findings were compared to those of the preoperative echocardiogram. Patients with moderate or severe tricuspid or common atrioventricular valve regurgitation preoperatively had a significant reduction in their survival when contrasted with patients with no or mild atrioventricular valve regurgitation. We therefore conclude that tricuspid or common atrioventricular valve competence is a significant factor in long-term survival after palliative surgery for hypoplastic left-heart syndrome. This function, however, appears to be unaffected by palliation and remains relatively constant over the first 2 postoperative years.

Fate of the pulmonic valve after proximal pulmonary artery-to-ascending aorta anastomosis for aortic outflow obstruction

Transection of the main pulmonary artery and end-to-side anastomosis of the proximal pulmonary artery to the ascending aorta has been increasingly used in palliative surgery for cardiac malformations such as single ventricle with small outlet foramen (bulboventricular foramen) and hypoplastic left-heart syndrome. To evaluate pulmonary valve competence after this operation, we used color Doppler flow mapping to examine 45 survivors of pulmonary artery-to-ascending aorta anastomosis a median of 202 days postoperatively. Of 37 patients with hypoplastic left heart syndrome, mild regurgitation was detected in 9 (24%) and moderate regurgitation in 1 (3%). Of 8 with other lesions, mild regurgitation was observed in 2 and moderate regurgitation in 1. Seven of 11 patients imaged greater than or equal to 12 months postoperatively had regurgitation. In summary, one-fourth of survivors developed mild pulmonary regurgitation. Its presence should not be considered a contraindication to eventual application of Fontan's principle, although further follow-up appears warranted because the long-term fate of pulmonary valve function is not yet known.

Hemodynamic responses to isolated increments in heart rate by atrial pacing after a Fontan procedure

The physiologic role of the right ventricle has long been a subject of interest to physiologists. The Fontan operation provides a human model for studying the circulation in series devoid of a subpulmonic right ventricle. The hemodynamic response to isotonic exercise in this setting has been established, and differs appreciably from normal. However, the physiologic response to an increase in heart rate (atrial pacing) as an isolated variable has not been examined and compared to atrial pacing in hearts with two concordant subarterial ventricles. Accordingly, we compared the supine bicycle exercise response to rate-equivalent right atrial pacing in nine patients after atriopulmonary anastomoses (the Fontan operation) for single ventricle or tricuspid atresia. Cardiac index increased 77% with exercise (rest 2.6 L/min/m2; exercise 4.6 L/min/m2) but decreased 12% with atrial pacing (rest 2.5 L/min/m2; pacing 2.2 L/min/m2). Pulmonary arterial oxygen saturation declined significantly during exercise (rest 68%; exercise 31%) and during atrial pacing (control 72%; pacing 64%). The mean increment in pulmonary arterial pressure was 1.3 times greater with exercise (rest 14 mm Hg; exercise 20 mm Hg) than with pacing (control 12 mm Hg; pacing 16 mm Hg). Peak systemic arterial systolic pressure increased 14% with exercise but was unchanged by pacing. Systemic and pulmonary vascular resistances fell with exercise but changed insignificantly during atrial pacing. Stroke volume rose slightly with exercise but fell significantly with pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Palliative reconstructive surgery for hypoplastic left heart syndrome

From August, 1985, through August, 1987, 104 consecutive, nonselected neonates underwent palliation of hypoplastic left heart syndrome. The technique included pulmonary artery homograft augmentation of the diminutive ascending aorta and aortic arch, atrial septectomy, transection of the main pulmonary artery with patch closure of the distal main pulmonary artery, anastomosis of the proximal main pulmonary artery to the augmented ascending aorta, and a 4-mm, modified, right Blalock-Taussig (N = 21) or central (N = 83) shunt. There were 30 early and 11 late deaths. Early mortality was most commonly associated with hypoventilation. Complications included development of aortic arch obstruction (N = 11) and progressive hypoxemia (N = 11). Alterations in surgical techniques and perioperative management should permit continued improvement in early and long-term survival.

Positive and negative control observations for the in vivo/in vitro rat liver assay for unscheduled DNA synthesis (UDS)

Positive and negative control data are shown for greater than 50 experiments conducted using the in vivo/in vitro rat liver unscheduled DNA synthesis (UDS) assay. In this assay, animals are dosed with the test agent and the liver is subsequently assessed for UDS by autoradiography and grain counting. The combined corn-oil negative control gave a value of -2.54 +/- 1.4 net gains (NG +/- SD; n = 77) and the positive control agent 6-p-dimethylaminophenylazobenzothiazole (6BT, dosed in vivo, animals sampled at 12 h) gave a value of +28.3 +/- 16.0 NG (+/- SD; n = 51). These data are briefly discussed, as are the reasons why this laboratory employs an in vivo (as opposed to an in vitro) positive control in each experiment.

Subaortic obstruction in complex congenital heart disease: management by proximal pulmonary artery to ascending aorta end to side anastomosis

Six patients with univentricular heart and one patient with d-transposition of the great arteries had transection of the main pulmonary artery with an end to side anastomosis of the main pulmonary artery to the ascending aorta to relieve subaortic obstruction. Two operations were performed as a palliative procedure within the first 6 months of life and five were performed as part of a definitive repair (four modified Fontan procedures and one repair of transposition of the great arteries with ventricular septal defect). There was one surgical death (14%) occurring 1 day postoperatively from low cardiac output. The remaining six patients are doing well 1 to 19 months postoperatively (mean 11.4 months). The proximal pulmonary artery to ascending aorta end to side anastomosis is an effective means of bypassing subaortic obstruction associated with complex congenital heart disease.

Pulmonary atresia with ventricular septal defect: preoperative and postoperative responses to exercise

Between April 1982 and June 1984, maximal exercise testing was performed 35 times in 34 consecutive patients with pulmonary atresia and ventricular septal defect (14 studies in patients without repair, 11 studies in patients with partial repair [insertion of a right ventricle to pulmonary artery conduit without ventricular septal defect closure] and 10 studies in patients with complete repair [insertion of a conduit with septal defect closure]). Total work performed, maximal power achieved, exercise time and maximal oxygen uptake were significantly greater in patients after partial or complete repair than in patients without repair. Systemic arterial blood oxygen saturations at rest and during exercise were directly related to the degree of repair. Although heart rate at rest in the three study groups was similar to that in a separate group of normal control subjects, patients in all three study groups had a blunted heart rate response to exercise. The ventilatory equivalent for oxygen was increased both at rest and during exercise for patients without conduit repair and those with a right ventricle to pulmonary artery conduit without ventricular septal defect closure but was similar to that of control subjects in the group with conduit insertion and septal defect closure. This study indicates that patients with pulmonary atresia and ventricular septal defect have decreased exercise tolerance both before and after corrective surgery. Exercise tolerance improves significantly after placement of a conduit from the right ventricle to the pulmonary artery with or without ventricular septal defect closure. Although no further improvement in exercise tolerance occurs with closure of the septal defect, ventilatory function and systemic arterial blood oxygen saturation are improved.

Cardiorespiratory response to exercise in Ebstein's anomaly

Fourteen patients with unrepaired Ebstein's anomaly underwent maximal exercise testing between October 1982 and April 1984. Compared with control subjects, these patients had significantly lower values for total work performed, exercise time, maximal oxygen uptake, blood oxygen saturation at rest and during exercise, and heart rate and systolic blood pressure during maximal exercise. They had a significant increase in heart rate at rest. The ventilatory equivalent for oxygen was increased significantly both at rest and during exercise. Thus, patients with Ebstein's anomaly have decreased exercise tolerance owing to both cardiac and respiratory limitations.

Statistical prediction of cardiac risk in patients who undergo vascular surgery

Since August 1982, an extensive computerized data base has been developed on all patients admitted to the Division of Vascular Surgery at the Ottawa Civic Hospital. For each patient, 180 variables are recorded, including information about preoperative risk factors and postoperative complications. Since cardiac complications are a major cause of mortality and morbidity, the data file has been used to study postoperative cardiac complications in patients who undergo arterial reconstructive operations. Between August 1982 and December 1983, 353 artery repairs were performed, excluding ruptured aneurysms. Cardiac complications developed following surgery in 56 patients. Risk factors were initially studied using contingency table analysis. Four of these factors were found to be significant: electrocardiographic evidence of previous myocardial infarction (p = 0.0003), nonspecific ST-segment changes (p = 0.0007), New York Heart Association classification of symptoms (p = 0.0003) and age (p = 0.01). A further statistical study was based upon multiple logistic regression. The authors believe that the identification of a high-risk group, using these criteria, is helpful in selecting patients for intensive preoperative investigation, including coronary arteriography.