Alternative sources of bioactive omega-3 fatty acids: what are the options?

PURPOSE OF REVIEW

The very-long chain (VLC) omega-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) promote optimal development, physiological function and healthy ageing and help to manage disease. EPA and DHA are sourced mainly from fish, which is not sustainable. This review explores alternative sustainable sources.

RECENT FINDINGS

Recent research confirms that higher intake and status of EPA and DHA are associated with health benefits including lower risk of incident type-2 diabetes and cardiovascular disease mortality. Meta-analyses confirm benefits of intravenous EPA and DHA in hospitalized adults. Algal oils and seed oils from some genetically modified (GM) plants are sources of EPA and DHA. An oil from GM camelina showed equivalence with fish oil in human trials. Ahiflower oil, a source of stearidonic acid, had biological effects in experimental studies that might translate into health benefits. An intravenous lipid emulsion based on Ahiflower oil has been tested in experimental research. Pine nut oil (PNO) is a source of pinolenic acid, which is not an omega-3 PUFA but has similar actions.

SUMMARY

Algal oils, oils from GM seed crops, Ahiflower oil and other sources of stearidonic acid, and nonomega-3 oils including PNO, are plant-sourced sustainable alternatives to fish-sourced VLC omega-3 PUFAs.

Omics biomarkers and an approach for their practical implementation to delineate health status for personalized nutrition strategies

Personalized nutrition (PN) has gained much attention as a tool for empowerment of consumers to promote changes in dietary behavior, optimizing health status and preventing diet related diseases. Generalized implementation of PN faces different obstacles, one of the most relevant being metabolic characterization of the individual. Although omics technologies allow for assessment the dynamics of metabolism with unprecedented detail, its translatability as affordable and simple PN protocols is still difficult due to the complexity of metabolic regulation and to different technical and economical constrains. In this work, we propose a conceptual framework that considers the dysregulation of a few overarching processes, namely Carbohydrate metabolism, lipid metabolism, inflammation, oxidative stress and microbiota-derived metabolites, as the basis of the onset of several non-communicable diseases. These processes can be assessed and characterized by specific sets of proteomic, metabolomic and genetic markers that minimize operational constrains and maximize the information obtained at the individual level. Current machine learning and data analysis methodologies allow the development of algorithms to integrate omics and genetic markers. Reduction of dimensionality of variables facilitates the implementation of omics and genetic information in digital tools. This framework is exemplified by presenting the EU-Funded project PREVENTOMICS as a use case.

Differential Effects of Ruminant and Industrial 18-Carbon trans-Monounsaturated Fatty Acids (trans Vaccenic and Elaidic) on the Inflammatory Responses of an Endothelial Cell Line

Endothelial dysfunction and inflammation are recognised factors in the development of atherosclerosis. Evidence suggests that intake of industrial trans fatty acids (TFAs) promotes endothelial dysfunction, while ruminant TFAs may have the opposite effect. The aim of this study was to compare the effects of elaidic acid (EA (18:1n-9t); an industrially produced TFA) and trans vaccenic acid (TVA (18:1n-7t); a natural TFA found in ruminant milk and meat) on inflammatory responses of endothelial cells (ECs). ECs (EA.hy926 cells) were cultured under standard conditions and exposed to TFAs (1 to 50 μM) for 48 h. Then, the cells were cultured for a further 6 or 24 h with tumour necrosis factor alpha (TNF-α, 1 ng/mL) as an inflammatory stimulant. ECs remained viable after treatments. TFAs were incorporated into ECs in a dose-dependent manner. Preincubation with EA (50 µM) increased production of MCP-1, RANTES, and IL-8 in response to TNF-α, while preincubation with TVA (1 µM) decreased production of ICAM-1 and RANTES in response to TNF-α. Preincubation with EA (50 µM) upregulated toll-like receptor 4 and cyclooxygenase 2 gene expression in response to TNF-α. In contrast, preincubation with TVA (1 µM) downregulated TNF-α induced nuclear factor kappa B subunit 1 gene expression. Preincubation of ECs with EA (50 µM) increased THP-1 monocyte adhesion. In contrast, preincubation of ECs with TVA (1 µM) reduced THP-1 monocyte adhesion, while preincubation of ECs with TVA (50 µM) decreased the level of surface expression of ICAM-1 seen following TNF-α stimulation. The results suggest that TVA has some anti-inflammatory properties, while EA enhances the response to an inflammatory stimulus. These findings suggest differential effects induced by the TFAs tested, fitting with the idea that industrial TFAs and ruminant TFAs can have different and perhaps opposing biological actions in an inflammatory context.

Anti-inflammatory effects of oleic acid and the anthocyanin keracyanin alone and in combination: effects on monocyte and macrophage responses and the NF-κB pathway

Monocyte recruitment and activation of macrophages are essential for homeostasis but are also related to the development and progression of cardiometabolic diseases. The management of inflammation with dietary components has been widely investigated. Two components that may influence inflammation are unsaturated fatty acids such as oleic acid (OA; 18:1cis-9) and antioxidant compounds like anthocyanins. Molecular and metabolic effects of such bioactive compounds are usually investigated in isolation, whereas they may be present in combination in foods or the diet. Considering this, we aimed to analyze the effects of OA and the anthocyanin keracyanin (AC) alone and in combination on toll-like receptor-mediated inflammatory responses in monocytes and macrophages. For this, THP-1-derived macrophages and monocytes were exposed to 3 treatments: OA, AC, or the combination (OAAC) and then stimulated with lipopolysaccharide. Inflammation-related gene expression and protein concentrations of IL-1β, TNF-α, IL-6, MCP-1, and IL-10 were assessed. Also, NFκBp65, IκBα, and PPAR-γ protein expression were determined. OA, AC, and OAAC decreased pNFκBp65, PPARγ, IκBα, TNF-α, IL-1β, IL-6, and MCP-1 and increased IL-10. MCP-1 protein expression was lower with OAAC than with either OA and AC alone. Compared to control, OAAC decreased mRNA for TLR4, IκKα, IκBα, NFκB1, MCP-1, TNF-α, IL-6, and IL-1β more than OA or AC did alone. Also, IL-10 mRNA was increased by OAAC compared with control, OA, and AC. In summary, OA and AC have anti-inflammatory effects individually but their combination (OAAC) exerts a greater effect.

A review of the functional effects of pine nut oil, pinolenic acid and its derivative eicosatrienoic acid and their potential health benefits

Pine nut oil (PNO) is rich in a variety of unusual delta-5-non-methylene-interrupted fatty acids (NMIFAs), including pinolenic acid (PLA; all cis-5,-9,-12 18:3) which typically comprises 14 to 19% of total fatty acids. PLA has been shown to be metabolised to eicosatrienoic acid (ETA; all cis-7,-11,-14 20:3) in various cells and tissues. Here we review the literature on PNO, PLA and its metabolite ETA in the context of human health applications. PNO and PLA have a range of favourable effects on body weight as well as fat deposition through increased energy expenditure (fatty acid oxidation) and decreased food energy intake (reduced appetite). PNO and PLA improve blood and hepatic lipids in animal models and insulin sensitivity in vitro and reduce inflammation and modulate immune function in vitro and in animal models. The few studies which have examined effects of ETA indicate it has anti-inflammatory properties. Another NMIFA from PNO, sciadonic acid (all cis-5,-11,-14 20:3), has generally similar properties to PLA where these have been investigated. There is potential for human health benefits from PNO, its constituent NMIFA PLA and the PLA derivative ETA. However further studies are needed to explore the effects in humans.

Robotic transanal minimally invasive surgery - technical, oncological and patient outcomes from a single institution

AIM

Robotic transanal minimally invasive surgery (R-TAMIS) is gaining traction around the globe as an alternative to laparoscopic conventional TAMIS for local excision of benign and early malignant rectal lesions. The aim was to analyse patient and oncological outcomes of R-TAMIS for consecutive cases in a single centre.

METHODS

A prospective analysis of consecutive R-TAMIS procedures over a 12-month period was performed. Data were collated from hospital databases and theatre registers.

RESULTS

Eleven patients (six men, five women), mean age 69.81 years (51-92 years), underwent R-TAMIS over 12 months utilizing a da Vinci Xi platform. The mean lesion size was 36 mm (20-60 mm) with a mean distance from the anal verge of 7.5 cm (3-14 cm). Five lesions were posterior in anatomical location, four anterior, one right lateral and one left lateral. All procedures were performed in the lithotomy position using a GelPOINT Path Platform. Mean operative time was 64 min (40-100 min). Complete resection was achieved in 10/11 patients with two patients being upgraded to a diagnosis of adenocarcinoma. Nine patients were diagnosed with dysplastic lesions. Four patients had a false positive diagnosis of an invasive tumour on MRI. Six patients required suturing for full-thickness resections. One patient had a postoperative bleed requiring repeat endoscopy and clipping. One patient (full-thickness resection of T3 tumour) proceeded to a formal resection without difficulty with no residual disease (T0N0, 0/22). One patient with a fully resected T2 tumour is undergoing a surveillance protocol. The mean length of stay was 1 day with two patients having a length of stay of 2 days and one patient of 4 days.

CONCLUSION

R-TAMIS could potentially represent a safe novel approach for local resection of rectal lesions.

Lowering the linoleic acid to alpha-linoleic acid ratio decreases the production of inflammatory mediators by cultured human endothelial cells

Alpha-linolenic acid (ALA) and linoleic acid (LA) are precursors for longer-chain more unsaturated fatty acids and for lipid signalling molecules that may influence inflammatory processes through a variety of mechanisms. The actions of LA and ALA may be divergent and interdependent. The aim of this study was to investigate the incorporation and metabolism of ALA and LA in cultured in EA.hy926 endothelial cells and the production of inflammatory mediators (VEGF, RANTES, ICAM-1, MCP-1, IL-6 and IL-8) by these cells when exposed to different concentrations of ALA, LA and ratios of LA:ALA. Human endothelial cells were cultured with either culture medium or culture medium supplemented with ALA, LA or various ratios of LA:ALA (1:4, 1:1, 4:1, 9:1 or 19:1) followed by 24 h TNF-α stimulation; the total concentration of ALA plus LA was kept constant at 100 μM. The incorporation and metabolism of ALA and LA was measured using gas chromatography. The production of inflammatory mediators in the supernatant was assessed using a Luminex Multi-Analyte kit. Both ALA and LA were incorporated and metabolised by the endothelial cells. Cells incubated with ALA had a statistically significantly lower production of VEGF, RANTES, ICAM-1, MCP-1 and IL-6 compared to cells incubated without additional ALA. LA was not found to exert pro-inflammatory effects. Cells incubated with low LA:ALA ratios had lower production of VEGF, RANTES, MCP-1 and IL-6 when compared with a LA:ALA ratio of 19:1. These findings suggest that a low LA:ALA ratio exerts anti-inflammatory effects by lowering the production VEGF, RANTES, ICAM-1, MCP-1 and IL-6 in TNF-α stimulated endothelial cells compared to a high ratio. These effects were likely mediated by ALA, but LA may also possess some anti-inflammatory effects.

Palmitoleic Acid has Stronger Anti-Inflammatory Potential in Human Endothelial Cells Compared to Oleic and Palmitic Acids

SCOPE

Fatty acids (FAs) may affect endothelial cell (EC) function, influencing atherogenesis and inflammatory processes. Palmitoleic acid (POA) has been described as an anti-inflammatory FA. However, its effects on ECs are underexplored. This study compares the effects of POA with those of palmitic acid (PA) and oleic acid (OA) on EC inflammatory responses.

METHODS AND RESULTS

EAHy926 cells (EC lineage) are exposed to PA, OA, or POA, and stimulated with tumor necrosis factor (TNF)-α. Associated with the FA's own incorporation, PA induces a twofold increase in arachidonic acid, while POA increases the amount of cis-vaccenic acid. PA, but not OA, enhances the production of IL-6 and IL-8 in response to TNF-α. In contrast, POA decreases production of monocyte chemotactic protein (MCP)-1, IL-6, and IL-8 compared to PA. TNF-α increases surface intercellular adhesion molecule-1 expression previously decreased by POA. TNF-α stimulation increases the expression of NFκB, cyclooxygenase (COX)-2, MCP-1, and IL-6 genes and reduces the expression of peroxisome proliferator-activated receptor (PPAR)-α gene. PA enhances the expression of MCP-1, IL-6, and COX-2 genes, while POA downregulates these genes, decreases expression of NFκB, and upregulates PPAR-α gene expression.

CONCLUSION

POA has anti-inflammatory effects on ECs stimulated with TNF-α and may counter endothelial dysfunction.

Membrane cholesterol is essential for triterpenoid saponin augmentation of a saporin-based immunotoxin directed against CD19 on human lymphoma cells

Triterpenoid saponins from Saponinum Album (SA) exert potent lytic effects on eukaryotic cell plasma membranes and, when used at sub-lytic concentrations, significantly augment the cytotoxicity of saporin-based immunotoxins (IT). To help elucidate the mechanism(s) behind these two phenomena we investigated the role of cholesterol to both. Human Daudi lymphoma cells were lipid deprived using a combination of three different approaches. Following treatment, the total cellular lipid content was analyzed by electrospray ionization mass spectrometry (ESI-MS) and plasma membrane (PM) cholesterol content measured using the lipophilic fluorescent probe NR12S. Maximal lipid deprivation of cells resulted in a complete loss of sensitivity to lysis by SA. Similarly augmentation of the anti-CD19 immunotoxin (IT) BU12-SAPORIN by SA was lost but without a concomitant loss of intrinsic IT cytotoxicity. The lytic activity of SA was restored following incubation of lipid deprived Daudi cells with Synthecol or LDL. The augmentative effect of SA on IT cytotoxicity for Daudi cells was restored following repletion of PM cholesterol levels with LDL. NR12S fluorescence and ESI-MS analysis of cellular lipids demonstrated that restoration of SA lytic activity by Synthecol was entirely due to increased PM cholesterol levels. Restoration of cellular and PM cholesterol levels by LDL also restored the augmentative effect of SA for IT, an effect associated with repletion of PM cholesterol with minor changes in some phospholipid species. These results indicate that the lytic and IT augmentative properties of SA are cholesterol-dependent in contrast to intrinsic IT cytotoxicity that is at least partially cholesterol independent.

An atypical genotype of Toxoplasma gondii as a cause of mortality in Hector's dolphins (Cephalorhynchus hectori)

Hector's dolphins (Cephalorhynchus hectori) are a small endangered coastal species that are endemic to New Zealand. Anthropogenic factors, particularly accidental capture in fishing nets, are believed to be the biggest threat to survival of this species. The role of infectious disease as a cause of mortality has not previously been well investigated. This study investigates Toxoplasma gondii infection in Hector's dolphins, finding that 7 of 28 (25%) dolphins examined died due to disseminated toxoplasmosis, including 2 of 3 Maui's dolphins, a critically endangered sub-species. A further 10 dolphins had one or more tissues that were positive for the presence of T. gondii DNA using PCR. Genotyping revealed that 7 of 8 successfully amplified isolates were an atypical Type II genotype. Fatal cases had necrotising and haemorrhagic lesions in the lung (n=7), lymph nodes (n=6), liver (n=4) and adrenals (n=3). Tachyzoites and tissue cysts were present in other organs including the brain (n=5), heart (n=1), stomach (n=1) and uterus (n=1) with minimal associated inflammatory response. One dolphin had a marked suppurative metritis in the presence of numerous intra-epithelial tachyzoites. No dolphins had underlying morbillivirus infection. This study provides the first evidence that infectious agents could be important in the population decline of this species, and highlights the need for further research into the route of entry of T. gondii organisms into the marine environment worldwide.

Three- and four-dimensional reconstruction of intra-cardiac anatomy from two-dimensional magnetic resonance images

The present study was designed to evaluate the feasibility and clinical usefulness of three-dimensional (3D) reconstruction of intra-cardiac anatomy from a series of two-dimensional (2D) MR images using commercially available software. Sixteen patients (eight with structurally normal hearts but due to have catheter radio-frequency ablation of atrial tachyarrhythmias and eight with atrial septal defects (ASD) due for trans-catheter closure) and two volunteers were imaged at 1T. For each patient, a series of ECG-triggered images (5 mm thick slices, 2-3 mm apart) were acquired during breath holding. Depending on image quality, T1- or T2-weighted spin-echo images or gradient-echo cine images were used. The 3D reconstruction was performed off-line: the blood pools within cardiac chambers and great vessels were semi-automatically segmented, their outer surface was extracted using a marching cube algorithm and rendered. Intra- and inter-observer variability, effect of breath-hold position and differences between pulse sequences were assessed by imaging a volunteer. The 3D reconstructions were assessed by three cardiologists and compared with the 2D MR images and with 2D and 3D trans-esophagal and intra-cardiac echocardiography obtained during interventions. In every case, an anatomically detailed 3D volume was obtained. In the two patients where a 3 mm interval between slices was used, the resolution was not as good but it was still possible to visualize all the major anatomical structures. Spin-echo images lead to reconstructions more detailed than those obtained from gradient-echo images. However, gradient-echo images are easier to segment due to their greater contrast. Furthermore, because images were acquired at least at ten points in the cardiac cycles for every slice it was possible to reconstruct a cine loop and, for example, to visualize the evolution of the size and margins of the ASD during the cardiac cycle. 3D reconstruction proved to be an effective way to assess the relationship between the different parts of the cardiac anatomy. The technique was useful in planning interventions in these patients.

Simultaneous flow cytometric measurement of K-562 megakaryocytic differentiation and CD56+ large granular lymphocyte cytotoxicity

K-562 cells have the capacity to undergo multi-lineage differentiation, which may be crucial to their ability to serve as target reservoirs for CD56+ large granular lymphocytes (LGL). Conventional techniques using chromium release assays to measure lymphocyte-mediated cytotoxicity suffer from disadvantages, including radioactive contamination and the inability to simultaneously determine K-562 and/or CD56+ lymphocyte phenotypes. We illustrate here a three-color flow cytometric method providing for the simultaneous evaluation of K-562-CD56+ LGL binding, K-562 cell viability, and the status of K-562 cell differentiation. Phorbol 12-myristate 13-acetate (PMA) engenders megakaryocytic differentiation in K-562 cell populations, as measured by presentation of the beta(3) integrin (gpIIIa, CD61), while maintaining a negative expression of MHC-I and MHC-II molecules. Using the auto-fluorescence of K-562 cells, flow cytometry can be used to demonstrate a significant decrease in CD56+ LGL activity against K-562 cells in populations pre-incubated with PMA. The capacity of three-color flow cytometry to measure lymphocyte-target cell binding and cell death kinetics, while simultaneously determining target cell phenotype, permits the specific localization of CD61-expressing K-562 cells to areas inconsistent with CD56+ LGL-mediated patterns of lysis.

PMA-treated K-562 leukemia cells mediate a TH2-specific expansion of CD4+ T cells in vitro

Highly enriched preparations of human CD3+CD4+ T-lymphocytes were stimulated with mitogen or OKT3 to determine the capacity of K-562 cells to function as accessory cells. Phorbol 12-myristate 13-acetate (PMA)-treated K-562 cells were induced to differentiate along the megakaryocytic lineage and could supplant monocyte-accessory cell function. Intracytoplasmic analysis of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) established that IL-4, and not IFN-gamma, was preferentially produced by the activated lymphocytes. This polarized stimulation is compatible with a type 2 or humoral immune response of purified T cells co-cultured with differentiated K-562 cells in vitro, and may have implications in immunoregulation due to disease progression.

Evaluation of myocardial perfusion using positron emission tomography in infants following a neonatal arterial switch operation

This study was performed to examine the use of positron emission tomography (PET) as a method of evaluating myocardial perfusion after the arterial switch operation for correction of transposition of the great arteries. Eleven asymptomatic patients (median age 2.3 years, range 1.3-4.3 years) post successful neonatal arterial switch repair for transposition underwent cardiac PET scanning using N(13) ammonia before and after dipyridamole infusion. Reconstructed data from static scans were analyzed for regional perfusion defects before and after pharmacological stress. Simultaneous assessment of coronary flow before and after stress was performed using a Patlak graphical analysis of data from dynamic scans. Results obtained from PET scanning were correlated with patterns of coronary artery anatomy, electrocardiogram (ECG) recordings, and echocardiographic evaluation. PET scanning demonstrated normal distribution of myocardial perfusion before and after stress in all but one patient, who was found to have a discrete inferior transmural perfusion defect. The defect was well correlated with perioperative ECG changes and a complicated postoperative course. Myocardial blood flow before dipyridamole (0.690 ml/min/g) was similar to reported adult rest values. There was a small but significant (p < 0.002) increase in myocardial blood flow after dipyridamole stress with a mean coronary flow reserve of 1.19 (+/-0.103). Echocardiographic evaluation failed to demonstrate significant wall motion abnormalities in any of the patients. Cardiac PET scanning is a reliable noninvasive method for evaluation of myocardial perfusion in small children. In this study, the incidence of myocardial perfusion defects after the arterial switch operation is lower than previously reported. The data obtained concerning coronary flow and coronary flow reserve after the arterial switch need to be interpreted with caution because normal data in children are not available.

The effects of intensity on the energetics of brief locomotor activity

The energetic costs associated with locomotion are often estimated only from the energy expended during activity and do not include the costs incurred during recovery. For some types of locomotion, this method overlooks important aspects of the metabolic costs incurred as a result of the activity. These estimates for energetic cost have also been predicted from long-duration, low-intensity activities that do not necessarily reflect all the behavior patterns utilized by animals in nature. We have investigated the effects of different activity intensities on the metabolic expenditure (per unit distance traveled) associated with brief exercise, and offer a more inclusive analysis of how the energetics of short-duration activities might be analyzed to estimate the costs to the animal. Mice ran on a treadmill for 15 or 60 s at 25 %, 50 % or 100 % of maximum aerobic speed (MAS) while enclosed in an open-flow respirometry system. Following the run, each mouse was allowed to recover while remaining enclosed in the respirometry chamber. Excess exercise oxygen consumption (EEOC), the excess volume of oxygen consumed during the exercise period, increased with the duration and increased linearly with the intensity of exercise. In contrast, the volume of oxygen consumed during the recovery period, or excess post-exercise oxygen consumption (EPOC), was independent of exercise intensity and duration and accounted for more than 90 % of the total metabolic cost. The net cost of activity (C(act)), calculated by summing EEOC and EPOC and then dividing by the distance run, increased as both activity duration and intensity decreased. The values for C(act) ranged from 553 ml O(2)g(−)(1)km(−)(1) for a 15 s run at 25 % MAS to 43 ml O(2)g(−)(1)km(−)(1) for a 60 s run at 100 % MAS. Combining these data with data from a companion paper, we conclude (1) that EPOC is independent of both the duration and intensity of activity when exercise duration is brief in mice, (2) that EPOC accounts for a majority of the oxygen consumed as a result of the activity when exercise durations are short, and (3) that animals can minimize their energy expenditure per unit distance by running faster for a longer period.

Differential regulation of interleukin-1alpha and interleukin-1beta in K-562 cells

Interleukin (IL)-1alpha and IL-1beta are encoded by two separate genes, but both function as comitogens for lymphocyte activation. In this study, we observed K-562 cells to express constitutively mRNA for IL-1alpha, although IL-1alpha was not detected in the growth-conditioned medium (GCM). However, IL-1beta mRNA was not expressed unless the cells had been treated with phorbol myristate acetate (PMA). Both IL-1alpha and IL-1beta were detected in the GCM after the cells had been cultured with PMA, suggesting that IL-1 elaboration required PMA treatment. The K-562 cells treated with PMA differentiated to the myeloblastic stage, as observed by nuclear morphologic properties by electron microscopy. PMA treatment induced de novo expression of CD61 or gpIIIa, a marker associated with megakaryoblasts. These results showed that although K-562 cells constitutively expressed IL-1alpha mRNA, PMA treatment was required for secretion. On the other hand, both the expression and secretion of IL-1beta required treatment with PMA. This study showed that K-562 cells treated with PMA differentiated to the myeloblastic stage and expressed and secreted IL-1alpha and IL-1beta.

Effects of modified and classic Blalock-Taussig shunts on the pulmonary arterial tree

BACKGROUND

The aim of this study was to assess by angiography the late effects of both classic and modified Blalock-Taussig shunts in terms of growth and development of stenosis and distortion.

METHODS

At a mean of 51 months postoperatively, we retrospectively reviewed the results in 78 patients who underwent creation of Blalock-Taussig shunts (25 classic and 71 modified).

RESULTS

At the level of the anastomosis, the shunt caused a reduction in diameter of the pulmonary artery in 49% of all shunts, major stenosis (>50% narrowing of the lumen) in 14%, and distortion of the pulmonary artery in 19%, findings that did not correlate with the type of shunt. Distortion did correlate with younger age at the time of shunt operation (p=0.01).

CONCLUSIONS

After a Blalock-Taussig shunt, growth of the pulmonary arteries occurred but did not exceed the normal growth of the pulmonary arterial tree. Moreover, a shunt procedure can cause distortion and stenosis of the pulmonary artery, which may have important implications for future corrective surgical intervention. All these findings support earlier complete surgical repair of correctable congenital cardiac defects.

Growth of the right ventricle after successful transcatheter pulmonary valvotomy in neonates and infants with pulmonary atresia and intact ventricular septum

OBJECTIVES

Since 1990, transcatheter pulmonary valvotomy has become an alternative to surgical valvotomy in the management of neonates and infants with pulmonary atresia and intact ventricular septum. We sought to determine whether right ventricular growth after transcatheter pulmonary valvotomy is commensurate with body growth.

METHODS

Laser or radiofrequency-assisted balloon valvotomy was attempted in 12 neonates and infants with pulmonary atresia and intact ventricular septum. Tricuspid and mitral valve dimensions were measured retrospectively on the cross-sectional echocardiograms performed before the procedure and during follow-up. Z-values were used to standardize tricuspid valve dimensions with body size.

RESULTS

The atretic pulmonary valve was successfully perforated and dilated in nine of 12 patients. Five of these nine patients required additional transcatheter or surgical procedures to augment the pulmonary blood flow. Of six survivors, five are regularly followed up with a median follow-up of 60 months (range 37 to 68 months). All five have two-ventricle circulation, two of the five patients requiring surgical enlargement of the right ventricular outflow tract with or without closure of the atrial septal defect. Echocardiographic tricuspid valve dimensions and Z-values before transcatheter valvotomy tended to be smaller in the patients who died than in the survivors. In the survivors, the absolute tricuspid valve dimensions increased after valvotomy but the Z-values tended to decrease or stayed constant.

CONCLUSIONS

Transcatheter valvotomy is a good alternative to surgical valvotomy in patients with pulmonary atresia and intact ventricular septum. Two-ventricle circulation can be achieved despite subnormal right ventricular growth.

Deadenylation-dependent and -independent decay pathways for alpha1-tubulin mRNA in Chlamydomonas reinhardtii

The alpha- and beta-tubulin mRNAs of Chlamydomonas reinhardtii exhibit different half-lives under different conditions: when expressed constitutively, they degrade with half-lives of about 1 h, whereas when induced by deflagellation, they degrade with half-lives of only 10 to 15 min. To investigate the decay pathway(s) used under these two conditions, an alpha1-tubulin gene construct which included an insert of 30 guanidylate residues within the 3' untranslated region was introduced into cells. This transgene was efficiently expressed in stably transformed cells, and the mRNA exhibited constitutive and postinduction half-lives like those of the alpha1-tubulin mRNA. Northern blot analysis revealed the occurrence of a 3' RNA fragment derived from the poly(G)-containing alpha1-tubulin transcripts. The 3' fragment was shown to accumulate as full-length mRNA disappeared in actinomycin D-treated cells, indicating a precursor-product relationship. Insertion of a second poly(G) tract upstream of the first resulted in accumulation of only a longer 3' fragment, suggesting that the decay intermediate is generated by 5'-to-3' exonucleolytic digestion. A translational requirement for generation of the 3' fragment was demonstrated by experiments in which cells were deflagellated in the presence of cycloheximide. Analysis of fragment poly(A) length revealed that the fragments were, at most, oligoadenylated in nondeflagellated cells but had a long poly(A) tail in deflagellated cells. These findings suggest that the oligoadenylated fragment is a decay intermediate in a deadenylation-dependent, constitutive degradation pathway and that the requirement for deadenylation is bypassed in deflagellated cells. This represents the first example in which a single transcript has been shown to be targeted to different decay pathways under different cellular conditions.

EPOC and the energetics of brief locomotor activity in Mus domesticus

Excess post-exercise oxygen consumption (EPOC) is normally not considered in determinations of the metabolic cost of activity. This approach overlooks an important energetic cost that an animal incurs as a result of activity. To examine the importance of EPOC, we determined how the energetic cost of locomotion was affected by activity of short duration and high intensity. Mice were run at maximum speed on a treadmill while enclosed in an open-flow respirometry system. After sprinting for 5, 15, 30, or 60 sec, each mouse was allowed to recover while remaining enclosed in the respirometry chamber. Exercise oxygen consumption (EOC), the volume of oxygen consumed during the exercise, increased linearly with sprint duration. EPOC was determined as the volume of oxygen consumed after exercise ended until rest was reached. EPOC volumes were found to be constant following 5-60 sec of activity and accounted for > or = 90% of the total metabolic cost. The average EPOC volume of all treatments was 0.76 +/- 0.456 ml O2.gm-1. The net cost of activity (Cact), which considers both EOC and EPOC, decreased as sprint duration increased and varied between 500 ml O2.g-1.km-1 for 5 sec to 30 ml O2.g-1.km-1 for 60 sec of activity. The values for Cact were 15 to 250 times higher than traditional estimates of locomotor costs. From these data, it can be concluded that (1) EPOC is not affected by short exercise durations; (2) EPOC is an important energetic consideration when exercise durations are short; and (3) the metabolic costs of brief, vigorous locomotion may be much higher than previously estimated.

Single pass VDD pacing in children and adolescents

Use of a single pass lead for VDD pacing in complete heart block is well described in adults, but there are only brief reports of its use in children. We have used standard adult size single pass leads in 13 children and adolescents aged 3.7-17.2 years (mean 10.1 years) and weighing 13.5-76 kg (mean 34.8 kg). Congenital complete heart block was present in 7 patients, surgical complete heart block in 5 patients and 2:1 AV block of unknown cause in 1 patient. In four patients, the VDD system was their first pacing system. In nine of the patients, 1-6 previous systems had been used and simultaneous extraction of ventricular leads and/or atrial leads was performed. Leads of four different types were used: Brilliant IMP15Q, Brilliant + IMR15Q, CapSure 5032, and Unipass 425-13 with 4 different generators: Saphir 600, Saphir II 620, Thera VDD 8948, and Unity 292-07. At implantation, via a subclavian vein puncture, excess lead was advanced into the right atrium to allow both atrial sensing and slack for further growth. Ventricular thresholds ranged from 0.2-0.7 V. The minimal atrial amplitude was 0.7-4 mV and the maximum amplitude was 2.5-8 mV. There were no complications. All patients have maintained adequate atrial signals for reliable pacing with follow up of 3-36 months (mean 17.6 months) during which time some have undergone considerable growth. Reliable atrial synchronous ventricular pacing is possible in growing children with complete heart block using a standard adult single pass lead.

Transcatheter closure of patent arterial ducts using controlled-release coils

OBJECTIVE

To determine the efficacy of transcatheter closure of patent arterial ducts using controlled-release coils.

DESIGN

Transcatheter closure of patent arterial ducts was attempted in 52 patients using controlled-release coils.

SETTING

For the study, four tertiary paediatric cardiology units were used, two of which were in the U.K., one in Italy and one in Turkey.

PATIENTS

The 52 patients ranged in age between 3-5 months and 61 years (median 3-5 years), and weighted between 4.5 kg and 62 kg. The duct diameters were 1 mm to 6.5 mm.

RESULTS

In four patients the ducts were too large for safe release of the coils. In the remaining 48, one coil was inserted in 33 patients, two coils in nine, three coils in four and four coils in two patients. Immediately at the end of the procedure, the duct was completely occluded in 26/47 (55%) patients. Haemolysis occurred in one patient, in whom the coil was removed by a snare catheter and a large umbrella device was implanted with resolution of the haemolysis. Coil embolization to the pulmonary artery occurred in five (10%) patients. All were easily retrieved and replaced by larger coils. At the latest follow-up by colour Doppler echocardiography, the duct was completely occluded in 44/47 (94%) patients.

CONCLUSIONS

Transcatheter closure of patent arterial ducts by controlled-release coils is effective and safe. Even when more than one coil is inserted the technique is still less cumbersome and considerably cheaper than transcatheter umbrella closure.

Surgical management of colorectal metastases to the liver: role of resection and cryosurgery

Long-term results of 41 patients who underwent hepatic resection and early experience with 21 patients treated by hepatic cryosurgery alone or combined with resection for colorectal metastases are presented. Patients treated by resection had three or fewer metastases, no perioperative mortality, and a mean follow-up of 43.5 months. The five-year overall survival is 34% with a median survival of 48 months. By multivariate analysis, only transfusions correlated significantly with survival, but in a negative manner (p = 0.05). A mean of 4.3 units were transfused per patient, though only 25 patients actually received transfusions.

Evolving use of embolisation coils for occlusion of the arterial duct

OBJECTIVE

To assess the outcome of arterial duct occlusion with coils chosen according to the duct morphology.

DESIGN

Retrospective study.

SETTING

Paediatric cardiology centre.

PATIENTS

Coil occlusion was attempted in 57 patients aged 0.5 to 15 (median 3.7) years and weighing 5-59 (median 14) kg between January 1991 and December 1995. A residual leak was present in 8 patients after umbrella closure and in 4 patients after duct ligation.

METHODS

Coils of 4 different types were implanted through 4 or 5 F femoral artery catheters. Platinum or Interlocking Detachable 0.018 inch coils were deployed completely inside tubular ducts. Gianturco or PDA controlled release 0.038 inch coils were implanted to straddle short, post ligation and post umbrella ducts.

RESULTS

Coil implantation was successful in 54/57 patients. At 1 year the cumulative occlusion rate was 53/57 ducts (93%) on an intention to treat analysis. A single coil was implanted in 37 (69%), 2 coils in 10 (19%), 3 coils in 3 (5%) and 4 coils in 4 (7%) of the 54 successful procedures. Duct occlusion was documented at the end of the procedure in 31%, by the following day in 83%, by 6 weeks in 87%, by 6 months in 96%, and by 1 year in 98%. Coil embolisation occurred in 6/58 procedures (10%), with a 50% rate in the first year of implantation (1/2 patients) falling to 7% in the last year (3/42 patients). All embolised coils were easily retrieved.

CONCLUSIONS

Occlusion of small to moderate size arterial ducts, including residual post umbrella or post ligation ducts, was readily accomplished by coils selected according to the duct anatomy. This has both cost and practical benefits.

Medium-term results of experimental stent implantation into the ductus arteriosus

Balloon dilation is disappointing in maintaining patency of the arterial duct. In neonatal lambs, stent implantation in the arterial duct results in significantly larger ducts with greater pulmonary blood flow than balloon dilation. Little is known, however, about the duration of duct patency after stent implantation. The outcome of stent implantation into the arterial duct in 12 lambs was observed over a period of 1 to 24 months. Stents (Wallstent in 9, Tower stent in 3) were implanted after recanalizing the occluded duct at 2 to 7 days of age. Heparin was given only during the procedure, but no further anticoagulants were used. Angiographic or postmortem evaluations were made at 1, 1.5, 2, 3, 4, 6, 12, 16, and 21 months in a subgroup of 9 lambs who did not undergo reinterventions. The duct was patent in all these except for one studied at 16 months. Neointima initially developed in the center of the stent before extending toward the orifices, eventually burying the metal strands in contact with the wall. From 4 to 6 months onward stenoses were present inside some of the stents. When the stent did not protrude into the aorta, neointima extended over the duct orifice. Metal strands that were not in contact with the duct wall were incompletely covered with endothelial cells, platelets, and fibrin strands, but no thrombi were noted. Late balloon dilation of the stented duct was performed in two lambs increasing the pulmonary artery blood flow. In one lamb the neointimal lining was successfully removed at 14 months with an atherectomy catheter. Stent implantation into the arterial duct can maintain patency up to 21 months and could be considered as an alternative to neonatal systemic to pulmonary artery shunt operations. Neointimal proliferation and stenosis formation, however, is a major limitation that may eventually lead to a reduction in the pulmonary artery blood flow.

Use of interlocking detachable coils in embolization of coronary arteriovenous fistulas

Thirteen patients underwent transcatheter closure of coronary artery fistulas using interlocking detachable coils alone or combined with fibered coils. Complete occlusion was achieved in 92% of patients; although inadvertent embolization of coils occurred in 23% of patients, all these coils were easily retrieved using snares.

Soft tissue abscesses associated with parenteral drug abuse: presentation, microbiology, and treatment

Abscess formation at the site of drug injection is the commonest infectious complication in drug addicts. This study characterizes the clinical presentation of the condition, its current microbiology, and treatment outcome. All patients presenting for treatment of soft tissue abscesses associated with parenteral drug abuse over a 21-month period were studied. Sixty-six patients with 70 subcutaneous abscesses after injection of cocaine (85%), heroin (5%), or unreported drugs (10%) were identified. Only 42% were febrile (T > 37.5 degrees C), 54 percent had leukocytosis, and 47 percent had wound fluctuance. Wound cultures (243 isolates in 57 patients) grew predominately anaerobes (143 isolates) and facultative gram-positive cocci (88 isolates). Twenty-six blood cultures were obtained, and five (19%) were positive, two with the same bacteria isolated from the wound. Of the patients tested, 29 percent were positive for hepatitis B surface antigen and 9 percent for HIV. Simple incision and drainage was effective in all cases. Classical signs and symptoms of infection and abscess formation may be absent in this patient population. Many of these patients carry other blood-borne infections which the health professional must guard against. Cocaine injection, and "mixed" aerobic-anaerobic infections predominated, in contrast to earlier reports, when narcotics and aerobes predominated. Simple incision and drainage is adequate treatment; antibiotics, when given, should cover gram-positive and anaerobic bacteria; gram-negative coverage is unnecessary.

Angiotensin-converting enzyme (ACE) gene polymorphism in type II diabetic patients with increased albumin excretion rate

Approximately one in three patients with diabetes is at risk of developing kidney disease, despite current methods of treatment. It has long been suspected that diabetic kidney disease has a genetic basis, but this has been difficult to prove. Polymorphisms of the angiotensin-converting enzyme (ACE) gene have been shown to be related to the occurrence of nephropathy in type I diabetic patients. This study showed that there was no association in the ACE genotype frequency and increased albumin excretion rate in type II diabetic patients.

In vitro percutaneous absorption of arildone, a highly lipophilic drug, and the apparent no-effect of the penetration enhancer Azone in excised human skin

PURPOSE

Arildone, a novel lipophilic antiviral drug when evaluated in Clinical Trials showed limited skin absorption and antiviral efficacy. These studies were conducted to explain the apparent poor absorption characteristics and attempt to promote skin absorption by using Azone, a penetration enhancer.

METHODS

Standard in vitro skin permeation methods using excised human skin were employed to characterise the absorption of Arildone. 14C-Arildone was used to estimate the distribution in skin layers by scintigraphic and autoradiographic procedures.

RESULTS

The aqueous solubility and distribution constant values for Arildone were 2 micrograms ml-1 and 5 x 10(5) (isopropyl myristate/water), respectively. Absorption through full thickness skin or stratum corneum-viable epidermal membranes (diffusional resistant dermis removed), from a propylene glycol vehicle, was slow and the addition of Azone had no effect on the permeation rate. Distribution studies showed accumulation of Arildone in the stratum corneum. The concentration of Arildone in the viable epidermis was estimated from sectioning the skin and was found to be in sufficient amounts (400 micrograms cm-3) to have potential antiviral activity.

CONCLUSIONS

The apparent accumulation of Arildone in the stratum corneum suggested that the hydrophilic skin region presented the main barrier to permeation. Azone which affected the permeability of the stratum corneum was therefore not effective at enhancing Arildone absorption. Vehicles which readily permeate and enhance the transfer of lipophilic drugs from the stratum corneum into the viable epidermis were recommended.

Tolerance of the developing heart to ischemia: impact of hypoxemia from birth

Many infants who require cardiac surgery have cyanotic heart disease. We assessed the relative tolerances to ischemia of hearts from immature normoxemic rabbits versus hearts from immature rabbits subjected to hypoxemia since birth. Normoxemic animals were raised from birth in an environment where the inspired fractional concentration of oxygen (FIO2) was 0.21; for the hypoxemic studies FIO2 was reduced to 0.09. Hearts (n = 6/group) from normoxemic and chronically hypoxemic rabbits at 7-12, 21-28, 35-44, and 51-56 days of age underwent aerobic "working" perfusion with Krebs bicarbonate buffer, and cardiac function was measured. Hearts were then arrested by a 3-min infusion with either cold (14 degrees C) Krebs buffer (hypothermia alone group) or St. Thomas' Hospital II solution (hypothermia plus cardioplegia group) before 6 h of hypothermic (14 degrees C) global ischemia. Hearts were reperfused, and postischemic creatine kinase leakage and recovery of function were measured. For hearts protected with hypothermia alone, recovery of aortic flow was better in hearts hypoxemic from birth compared with normoxemic controls at 7-12 days (78 +/- 7 vs. 60 +/- 6%, P < 0.05) and 21-28 days old (81 +/- 12 vs. 26 +/- 28%, P < 0.05). Protection with hypothermia plus cardioplegia was also better in hearts hypoxemic from birth compared with normoxemic controls at 7-12 days (74 +/- 8 vs. 63 +/- 10%, P < 0.05) and 21-28 days old (84 +/- 3 vs. 71 +/- 5%, P < 0.05). Protection with hypothermia alone and hypothermia plus cardioplegia was no different within chronically hypoxemic age groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transcatheter retrieval of misplaced therapeutic embolisation devices

OBJECTIVE

To assess the incidence and subsequent management of misplaced devices as a complication of therapeutic embolisation procedures.

DESIGN

Retrospective review of case notes, cardiac catheterisation reports, and angiograms.

SETTING

Tertiary referral centre for congenital heart disease.

PATIENTS

205 consecutive children and adults undergoing therapeutic embolisation for congenital heart disease in the 10 years up to 1 April 1993. This group had 231 therapeutic embolisation procedures at 241 sites using coils, umbrella devices, or detachable balloons.

MAIN OUTCOME MEASURES

Incidences of misplacement and retrieval of the device; morbidity and mortality.

RESULTS

The incidence of misplacement was 3% (10/332) of devices deployed and 4.3% (10/231) of procedures performed. Retrieval from distal pulmonary arteries was not attempted in two patients, but transcatheter retrieval of coils and umbrellas from systemic and pulmonary vessels, using snares or retrieval baskets, was successful in the remaining eight. There were no deaths or serious sequelae related to the procedure, but one patient required femoral arteriotomy for removal of an umbrella device retrieved only as far as the groin. In four of the five most recent cases, the misplaced device was retrieved and the therapeutic embolisation was completed at the same procedure.

CONCLUSIONS

Misplacement of a device during therapeutic embolisation is a recognised complication that can be satisfactorily dealt with by transcatheter retrieval without recourse to surgery. For retrieval to be successful it is important to have a wide selection of retrieval equipment available and to be conversant with its use.

Calcium and cardioplegic protection of the ischemic immature heart: impact of hypoxemia from birth

Because many infants who require cardiac operation have cyanotic heart disease, we determined whether the existing calcium content of St. Thomas' II solution (1.2 mmol/L) is optimal to protect the immature rabbit heart hypoxemic from birth during subsequent ischemia. Modified hypothermic St. Thomas' II solutions (calcium content, 0 to 2.4 mmol/L) were compared with hypothermic Krebs bicarbonate buffer in protecting chronically hypoxemic (PaO2 = 34 +/- 11 mmHg, SaO2 = 63% +/- 3%) versus normoxemic (PaO2 = 76 +/- 11 mmHg, SaO2 = 92% +/- 3%) immature hearts (7 to 12 days old) during ischemia. Hearts (n = 6 per group) underwent aerobic 'working' perfusion with Krebs bicarbonate buffer and cardiac function was measured. The hearts were then arrested with a 3 minute infusion of either cold (14 degrees C) Krebs buffer (1.8 mmol calcium/L) as hypothermia alone or modified St. Thomas' II solution before 6 hours of hypothermic (14 degrees C) global ischemia. Hearts were reperfused and postischemic enzyme leakage and recovery of function were measured. A bell-shaped dose-response profile was observed for recovery of postischemic aortic flow but not for postischemic creatine kinase leakage, with improved protection occurring at lower calcium concentrations. Optimal myocardial protection occurred at a calcium content of 0.4 mmol/L, which was significantly better than with hypothermia alone or standard St. Thomas' II solution. We conclude that the existing calcium concentration of St. Thomas' II solution is responsible, in part, for its inadequate protection of immature myocardium hypoxemic from birth during ischemia.

Influence of anatomic correction for transposition of the great arteries on myocardial perfusion: radionuclide imaging with technetium-99m 2-methoxy isobutyl isonitrile

OBJECTIVES

We sought to determine the incidence of late perfusion defects attributable to coronary artery mobilization in patients undergoing anatomic correction for complete transposition of the great arteries.

BACKGROUND

Anatomic correction (arterial switch procedure) is currently the surgical treatment of choice for complete transposition. From its conception, there has been concern about the impact on myocardial perfusion of the coronary artery mobilization and reimplantation involved in the correction. Previous studies have demonstrated myocardial perfusion defects in patients after correction, although a causal relation between coronary mobilization, and perfusion abnormality has not been established.

METHODS

In a case-comparison study designed to test this hypothesis, 29 children underwent imaging with technetium-99m 2-methoxy isobutyl isonitrile (technetium-99m mibi). Ten had undergone anatomic correction (arterial switch group; interval from operation 6.9 +/- 1.42 years [range 4.9 to 9.1]); 9 had required noncoronary open heart surgery for other cardiac lesions (post-bypass group; interval from operation 5.6 +/- 3.6 years [range 1.0 to 13.25]); and 10 had had no surgical procedure (control group). The latter group comprised children with atrial or ventricular septal defects who required a radionuclide study for shunt calculation. Planar studies were performed in all 29 children, and additional tomographic acquisition was achieved in 25. To assess reversibility of perfusion defects both an exercise and a rest planar study were performed in the arterial switch group.

RESULTS

Perfusion abnormalities were observed in seven of the nine children in the postbypass group and in all 10 children in the arterial switch group. The frequency of perfusion defects in these two groups was similar, with at least 25% of the tomographic segments reported being abnormal. The control group had significantly fewer defects than the other two groups (p = 0.02), with only 8% of the tomographic segments judged to be abnormal. In all except one patient in the arterial switch group, the segments reported as abnormal on the planar exercise study were either abnormal or equivocal on the rest study, indicating a fixed abnormality.

CONCLUSIONS

Although the precise etiology of these perfusion abnormalities cannot be defined from this study, these data suggest that their origin is related more to the insult of open heart surgery itself than to the coronary manipulation involved in the arterial switch procedure. The functional importance requires further study.

Effect of introducing balloon dilation of native aortic coarctation on overall outcome in infants and children

The outcome of 40 consecutive newborns and children with normal cardiac connections presenting with unoperated (i.e., no previous surgical or balloon dilation treatment) aortic coarctation since the introduction of balloon dilation as a treatment option (group A) was compared retrospectively with that of a similar cohort of 38 patients (group B) presenting in the period immediately before the introduction of balloon dilation. Group A consisted of 18 newborns (< 30 days) and 22 children and Group B consisted of 20 newborns and 18 children. In group A, 30 patients had balloon dilation but 10 underwent surgery because of parental preference, unfavorable anatomy or for logistic reasons. Group B had conventional surgical repair by various methods. All patients were followed up clinically by Doppler echocardiography and, when possible, by magnetic resonance imaging. Repeat cardiac catheterization was only performed in those with suspected recoarctation. Survival and freedom from reintervention were investigated using Kaplan-Meier analysis. Patients of all ages in group A and those who had balloon dilation were at higher risk for reintervention (25 and 30%, respectively, at 1 year) than those in group B or those who had surgery (20 and 18%, respectively, at 1 year). Mortality was not significantly different between groups A and B, but there were 2 neonatal deaths directly attributable to the dilation procedure. Two patients developed aneurysms after dilation. Balloon dilation is an effective treatment for unoperated coarctation, but the recoarctation rate appears to be higher than for surgery.

Evaluation of pulmonary artery anatomy using magnetic resonance: the importance of multiplanar and oblique imaging

Pulmonary artery anatomy was studied in 36 patients (age range 12 days to 12.83 years, mean 2.9 years) with right ventricular outflow tract obstruction over a 3-year period using a 1.5 Tesla Magnetic Resonance system. Gated spin-echo sequences were obtained in each patient. Image planes used were straight and oblique transverse, oblique coronal, and oblique sagittal. The studies were analyzed retrospectively and comparative angiographic, surgical, and postmortem data was available in all cases. As previously noted with other imaging modalities, multiple views and oblique cuts were found to increase significantly the quality and accuracy of the information acquired. In 12 of the 15 patients who had axial and coronal imaging of both branch pulmonary arteries, the pulmonary arteries were unequivocally demonstrated to at least the first hilar branch. However, early in our experience we missed a number of branch stenoses that developed following surgical anastomoses. These mistakes were caused by inadequate or inappropriate slice acquisition. Magnetic resonance is an important technique for imaging pulmonary arteries. Careful use of the appropriate imaging planes is essential for accurate demonstration of the anatomy.

Prenatal diagnosis and correction of congenital heart defects

The improvement in heart scanning expertise during the routine obstetric scan has resulted in more congenital heart disease being recognized prenatally. Early diagnosis of severe heart malformation results in the majority of parents choosing to interrupt the pregnancy or allows the mother to give birth in a centre with obstetric and paediatric cardiac facilities.

Use of a second transcatheter Rashkind arterial duct occluder for persistent flow after implantation of the first device: indications and results

OBJECTIVE

To assess the efficacy, feasibility, and most appropriate timing of the implantation of a second Rashkind arterial duct occluder because of persistent flow after the first device.

DESIGN

A prospective serial Doppler study of patients after the insertion of a Rashkind arterial duct occluder including a subgroup in whom a second device was implanted.

SETTING

A tertiary referral centre for congenital heart disease.

PATIENTS

144 patients aged 7 months to 67 years (median 3.38 years) who underwent transcatheter occlusion of patent arterial duct, 20 of whom had attempted implantation of a second device.

INTERVENTIONS

Implantation of a second device alongside the first was attempted in 20 of the patients with persistent residual flow.

MAIN OUTCOME MEASURES

Successful implantation of a second device, the incidence of complications, and the achievement of complete occlusion on follow up Doppler echocardiography. The time to complete occlusion in the whole group and factors predictive of persistent leak were also analysed.

RESULTS

Second devices were successfully implanted in 19 of 20 first attempts and in the remaining patient at the second attempt. Complete occlusion was found in 19 patients at a mean follow up of eight months. The complications included fracture of a guidewire requiring femoral arteriotomy for its removal in one patient and embolisation of a device in another. With a single device, persistence of residual flow six months after implantation and malposition of the device on the aortogram after implantation were predictive of continuing residual patency.

CONCLUSIONS

Implantation of a second device is safe, feasible, and effective and should be considered when residual flow persists beyond six months, or if malposition of the first device causes complications such as haemolysis.

Technique of percutaneous laser-assisted valve dilatation for valvar atresia in congenital heart disease

OBJECTIVE

To investigate the efficacy and safety of transcatheter laser-assisted valve dilatation for atretic valves in children with congenital heart disease.

DESIGN

Prospective clinical study.

SETTING

Supraregional paediatric cardiology centre.

SUBJECTS

Eleven children (aged 1 day-11 years; weight 2.1-35.7 kg) with atresia of pulmonary (10) or tricuspid (one) valve underwent attempted laser-assisted valve dilatation as part of the staged treatment of their cyanotic heart disease.

INTERVENTION

After delineating the atretic valve by angiography and/or echocardiography a 0.018 inch "hot tip" laser wire was used to perforate the atretic valve. Subsequently the valve was dilated with conventional balloon dilatation catheters up to the valve annulus diameter.

RESULTS

Laser-assisted valve dilatation was successfully accomplished in nine children. In two neonates with pulmonary valve atresia, intact ventricular septum, and coexistent infundibular atresia the procedure resulted in cardiac tamponade: one died immediately and one later at surgery. During a follow up of 1-17 months (mean 11) two infants with pulmonary valve atresia and intact ventricular septum died (one with congestive cardiac failure). The remainder are either well palliated and do not require further procedures (three), or are awaiting further transcatheter or surgical procedures because of associated defects (four).

CONCLUSIONS

Laser-assisted valve dilatation is a promising adjunct to surgery in this high risk group of patients. It may avoid surgery in some patients, and may reduce the number of surgical procedures in those requiring staged operations.

Accelerated poly(A) loss and mRNA stabilization are independent effects of protein synthesis inhibition on alpha-tubulin mRNA in Chlamydomonas

In Chlamydomonas, the usual rapid degradation of tubulin mRNAs induced by flagellar amputation is prevented by inhibition of protein synthesis with cycloheximide. Evidence is presented that the ability of cycloheximide to stabilize alpha-tubulin mRNA depends on the time of addition. Addition of cycloheximide to cells before induction strongly stabilizes the induced mRNAs, while addition after their synthesis stabilizes them only transiently. Moreover, cycloheximide inhibition does not stabilize the same alpha-tubulin mRNA species in uninduced cells. These results suggest that cycloheximide is not acting to stabilize the induced alpha-tubulin mRNAs simply by preventing ribosome translocation. The stabilized state of tubulin mRNA was found to correlate with its occurrence on smaller polysomes but larger EDTA-released mRNP particles than the unstable state. A second effect of cycloheximide on the metabolism of induced tubulin mRNAs is to accelerate complete poly(A) removal. This effect of cycloheximide inhibition, unlike stabilization, occurs whenever cycloheximide is added to cells, and appears unrelated to stabilization. The effect is shown to be mRNA-specific; poly(A)-shortening on the rbcS2 mRNA is not altered in the presence of cycloheximide, nor do completely deadenylated molecules accumulate. Experiments in which cells were released from cycloheximide inhibition suggest that deadenylated alpha-tubulin mRNAs may be less stable than their polyadenylated counterparts during active translation.

Tubulin mRNA instability and stabilization by protein synthesis inhibitors are reproducible in nontranslating extracts from Chlamydomonas

In Chlamydomonas reinhardtii, flagellar amputation stimulates an induction in the synthesis of flagellar proteins which allows the cells to rapidly regenerate their flagella. The induction involves the coordinate accumulation and rapid degradation of a large number mRNAs, including those encoding the tubulins. The post-induction degradation of induced tubulin mRNAs has been shown to differ from the constitutive turnover pathway in two ways: (1) the rate of degradation is accelerated, and (2) degradation is prevented by inhibition of protein synthesis. In this report, it is shown that the post-induction degradation of all deflagellation-induced mRNAs examined is prevented by cycloheximide (CX), suggesting they all may be degraded via the same pathway. A cell-free decay system has been developed to investigate the degradation pathway. At least two characteristics of tubulin mRNA degradation are reproducible in these extracts: (1) endogenous alpha-tubulin mRNA is less stable than constitutive mRNAs in the same extract and (2) alpha-tubulin mRNA in extracts prepared from CX-treated cells (CX extracts) is significantly more stable than it is in extracts from untreated cells (control extracts). This indicates that the mechanism by which CX blocks rapid degradation of tubulin mRNA in vivo is not simply by preventing its translation and suggests the involvement of an altered trans-factor. The difference in tubulin mRNA stability in the two extracts is maintained when the extracts are prepared under conditions that dissociate ribosomes from mRNPs, indicating intact polysome structure is not necessary. Tubulin mRNA-containing polysomes isolated from control and CX extracts are equally stable when assayed alone. However, the polysomes from control extracts are more sensitive to exogenous RNAse treatment than are those from CX extracts, indicating a structural difference. There are no detectable differences in soluble factors that influence tubulin mRNA degradation rate between control and CX extracts; addition of excess soluble factors to either control or CX extracts does not alter the tubulin mRNA degradation in the extract, nor does a simple one-to-one combination of the two extracts result in stabilization or destabilization of the whole population of tubulin mRNAs in the mixture. The deflagellation-induced mRNAs, as a group, are shown to be particularly susceptible to a nuclease activity in extracts, inhibitable by vanadyl ribonucleoside complexes, which does not appear to attack constitutive mRNAs. It is proposed that a structural difference in the tubulin mRNPs produced in the presence and absence of CX underlies their differences in stabilities, and that a common nuclease targets the induced flagellar protein mRNAs.

Magnetic resonance imaging of hearts with atrioventricular valve atresia or double inlet ventricle

OBJECTIVE

To investigate the effectiveness and limitations of magnetic resonance imaging in defining cardiac anatomy in patients with double inlet ventricle or atrioventricular valve atresia.

DESIGN

Magnetic resonance images were reviewed retrospectively without reference to other morphological data.

SETTING

A tertiary referral centre for paediatric cardiology.

PATIENTS

18 patients (aged 8 days to 27 years) with a suspected univentricular atrioventricular connection.

METHODS

Imaging by a 1.5 T whole body magnetic resonance system with imaging planes adjusted to individual patient anatomy to best define the cardiac morphology. A complete sequential diagnosis obtained from an independent interpretation of the images was compared with the diagnosis obtained from cross sectional echocardiography and angiocardiography.

RESULTS

There was substantial accord between the diagnosis from magnetic resonance alone and that from other methods. In the six instances where there was not accord the magnetic resonance diagnosis was considered to be correct in two cases and incorrect in three cases. In the remaining case no consensus could be reached. In eight patients magnetic resonance imaging provided anatomical information additional to that from other methods. The strengths of magnetic resonance were in imaging the pulmonary arteries and their abnormalities and identifying juxtaposed atrial appendanges but there were some deficiencies in identifying Blalock-Taussig shunts.

CONCLUSION

Magnetic resonance imaging provided detailed information about all aspects of cardiac morphology in patients with a suspected diagnosis of univentricular atrioventricular connection. Often it provided additional information to echocardiography. Its use in selected patients should give valuable complementary information.

Determinants of hemodynamic results of balloon dilation of aortic recoarctation

Between October 1982 and May 1990, balloon dilation of aortic recoarctation was attempted in 27 patients. In 1 case dilation was not performed owing to suspected aortic perforation. The remaining 26 patients had 30 procedures. The age at the first dilation ranged between 2.6 months and 18.3 years. After dilation, systolic gradient decreased from 49 +/- 17 mm Hg to 20 +/- 17 mm Hg (p less than 0.001). A reduction of gradient to less than or equal to 20 mm Hg occurred after the first dilation in 17 of 26 (65%) patients. Residual gradients between 25 and 80 mm Hg were present in the remaining 9 patients. During follow-up of 2 months to 6.7 years, 5 of 17 patients with a good initial result developed further recoarctation (2 had successful redilation, 2 had reoperation, and 1 is awaiting repeat dilation). Of 9 patients with gradients greater than 20 mm Hg after the first dilation, 1 had successful redilation and 3 had reoperation. The remaining 5 patients are being managed conservatively. 2 patients developed aneurysms after dilation (1 immediately and the other at 2 months). In all, 15 patients (58%) had a good, and 11 (42%) a poor late hemodynamic result. Aortic diameters at different levels of the aortic arch and at the reconstructed isthmus (normalized to the aorta at the level of the diaphragm) were significantly higher in the group with a good late result than in that with a poor one. Balloon/aortic diameter ratio at diaphragm level also had a significant influence on the late results.

Mobile encapsulated lipomas

Mobile encapsulated lipomas are a benign neoplastic process with pronounced mobility in the subcutaneous plane. Characteristic clinical and histologic features differentiate this distinctive entity from similar reactive adipose processes.