Carbon nanotube stimulation of human mononuclear cells to model granulomatous inflammation

OBJECTIVES

Sarcoidosis is a multisystem inflammatory granulomatous disease of unknown etiology. The disease most often affects the lung and leads to death in 5% of patients. Patients who die often succumb due to progressive fibrotic lung disease. Translational research in sarcoidosis is significantly limited by a paucity of available experimental models. Carbon nanotubes are released into the environment during fuel combustion, manufacturing, and natural fires. Exposed individuals are at risk for cancer, lung inflammation and other chronic pulmonary disorders, including diseases resembling sarcoidosis and pulmonary fibrosis. In this study, we developed and characterized an in vitro experimental model relevant to sarcoidosis using human peripheral blood mononuclear cells (PBMCs) exposed to multiwalled carbon nanotubes (MWCNTs).

METHODS

MWCNT-exposed PBMCs were cultured and analyzed by Giemsa staining, immunohistochemistry (IHC) and RNA-seq analysis on days 1 and 7. Normalization and differential expression were calculated using DESeq2, Limma and edgeR methods from Bioconductor (adjP, log2Fold change and rawP).

RESULTS

MWCNT stimulation of PBMCs from healthy subjects leads to the formation of granuloma-like cell clusters and stereotypical inflammatory cytokine secretion. PBMC transcriptomic analysis demonstrated activation of defense- and inflammation-related pathways, including the Jak-Stat pathway and TNF signaling pathway.

CONCLUSIONS

This model is unique, as cell clustering is seen in the absence of specific antigenic stimulation (e.g., mycobacterial) or the addition of exogenous cytokines. Modeling with PBMCs provides a platform for precision medicine and evaluation of future therapies for granulomatous and fibrotic lung diseases.

Mycosis Fungoides Preceding Pityriasis Lichenoides et Varioliformis Acuta by Twelve Years in a Pediatric Patient

ABSTRACT

A 15-year-old boy presented to the pediatric dermatology department with long-standing patch stage CD8+ mycosis fungoides and subsequent development of recurrent pityriasis lichenoides et varioliformis acuta eruptions. There have been rare reports of patients with chronic, recalcitrant pityriasis lichenoides developing mycosis fungoides, but we believe this to be the second case of mycosis fungoides preceding a diagnosis of pityriasis lichenoides, and the first case reported in the pediatric population.

Cytochemical Characterization of Cerebrospinal Fluid Macrophage Inclusions in Pediatric Patients Receiving Intrathecal Nusinersen (SPINRAZA®) for Spinal Muscular Atrophy

INTRODUCTION

Spinal muscular atrophy (SMA) is a debilitating neuromuscular disorder caused by biallelic deletion of the SMN1 gene. Nusinersen, an antisense oligonucleotide delivered intrathecally, binds to the pre-mRNA of SMN1's pseudogene, SMN2, to prevent exon skipping and produce functional SMN protein to compensate for the deficiency caused by SMN1 deletion.

CASE PRESENTATION

We reviewed 15 cerebrospinal fluid (CSF) cytology specimens from 8 patients receiving nusinersen for SMA. Macrophages with peculiar inclusions ("nusinophages") were seen in 8 specimens from 4 of the patients: 1 infant and 3 children with SMA type 1. This finding has only previously been reported in adults with SMA types 2 and 3 and in 2 infants with SMA type 1.

DISCUSSION/CONCLUSION

Specimens containing nusinophages had a significantly higher proportion of macrophages and lower proportion of lymphocytes than those in which nusinophages were not detected. The macrophage inclusions do not represent iron or microorganisms and instead are composed, at least in part, of glycosaminoglycans. Because CSF is a common specimen type, cytotechnologists and cytopathologists need to be aware of these inclusions, so they do not interpret them erroneously as evidence of infection or hemorrhage, especially in light of the fact that oligonucleotide therapy has been approved for a variety of conditions and is currently under investigation for intrathecal delivery in several other neurodegenerative disorders.

Age and gender specific pediatric reference intervals for aldolase, amylase, ceruloplasmin, creatine kinase, pancreatic amylase, prealbumin, and uric acid

BACKGROUND

Reference intervals can vary based on age and gender. Proper partitioning is necessary to classify health status in different age groups.

METHODS

Seven analytes; aldolase, amylase, ceruloplasmin, creatine kinase, pancreatic amylase, prealbumin and uric acid; were assayed on Roche Modular P analyzers using serum samples from 1765 children (867 females and 898 males; age range, 6 months to 17 y). Subjects 6 months up to 7 y were undergoing minor surgical procedures. Children 7 to 17 y were apparently healthy. Subjects with significant medical history or who were taking any medications were excluded.

RESULTS

Separate reference intervals for boys and girls were required for 33% of the groups. Aldolase showed gender variation in the 6-8, 12-14, and 15-17 y. Amylase was the only analyte that showed no significant gender differences within any age group. Both ceruloplasmin and uric acid had significant differences between the 12-14 and 15-17 y groups. Creatine kinase exhibited statistically significant gender differences in all age groups with the exception of 6-8 y.

CONCLUSION

We verified that when establishing pediatric reference intervals, partitioning by age and gender is frequently necessary.

Cardiac resynchronisation therapy in paediatric and congenital heart disease: differential effects in various anatomical and functional substrates

Background:

Cardiac resynchronisation therapy (CRT) is increasingly used in children in a variety of anatomical and pathophysiological conditions, but published data are scarce.

Objective:

To record current practice and results of CRT in paediatric and congenital heart disease.

Design:

Retrospective multicentre European survey.

Setting:

Paediatric cardiology and cardiac surgery centres.

Patients:

One hundred and nine patients aged 0.24–73.8 (median 16.9) years with structural congenital heart disease (n = 87), congenital atrioventricular block (n = 12) and dilated cardiomyopathy (n = 10) with systemic left (n = 69), right (n = 36) or single (n = 4) ventricular dysfunction and ventricular dyssynchrony during sinus rhythm (n = 25) or associated with pacing (n = 84).

Interventions:

CRT for a median period of 7.5 months (concurrent cardiac surgery in 16/109).

Main outcome measures:

Functional improvement and echocardiographic change in systemic ventricular function.

Results:

The z score of the systemic ventricular end-diastolic dimension decreased by median 1.1 (p<0.001). Ejection fraction (EF) or fractional area of change increased by a mean (SD) of 11.5 (14.3)% (p<0.001) and New York Heart Association (NYHA) class improved by median 1.0 grade (p<0.001). Non-response to CRT (18.5%) was multivariably predicted by the presence of primary dilated cardiomyopathy (p = 0.002) and poor NYHA class (p = 0.003). Presence of a systemic left ventricle was the strongest multivariable predictor of improvement in EF/fractional area of change (p<0.001). Results were independent of the number of patients treated in each contributing centre.

Conclusion:

Heart failure associated with ventricular pacing is the largest indication for CRT in paediatric and congenital heart disease. CRT efficacy varies widely with the underlying anatomical and pathophysiological substrate.

High frequency of submicroscopic genomic aberrations detected by tiling path array comparative genome hybridisation in patients with isolated congenital heart disease

BACKGROUND

Congenital heart disease (CHD) is the most common birth defect and affects nearly 1% of newborns. The aetiology of CHD is largely unknown and only a small percentage can be assigned to environmental risk factors such as maternal diseases or exposure to mutagenic agents during pregnancy. Chromosomal imbalances have been identified in many forms of syndromic CHD, but very little is known about the impact of DNA copy number changes in non-syndromic CHD.

METHOD

A sub-megabase resolution array comparative genome hybridisation (CGH) screen was carried out on 105 patients with CHD as the sole abnormality at the time of diagnosis.

RESULTS

There were 18 chromosomal changes detected, which do not coincide with common DNA copy number variants, including one de novo deletion, two de novo duplications and eight familial copy number variations (one deletion and seven duplications).

CONCLUSIONS

Our data show that submicroscopic deletions and duplications play an important role in the aetiology of this condition, either as direct causes or as genetic risk factors for CHD. These findings have immediate consequences for genetic counselling and should pave the way for the elucidation of the pathogenetic mechanisms underlying CHD.

Evidence for a multivalent interaction of symmetrical, N-linked, lidocaine dimers with voltage-gated Na+ channels

The interaction of symmetrical lidocaine dimers with voltage-gated Na+ channels (VGSCs) was examined using a FLIPR membrane potential assay and voltage-clamp. The dimers, in which the tertiary amines of the lidocaine moieties are linked by an alkylene chain (two to six methylene units), inhibited VGSC activator-evoked depolarization of cells heterologously-expressing rat (r) Na(v)1.2a, human (h) Na(v)1.5, and rNa(v)1.8, with potencies 10- to 100-fold higher than lidocaine (compound 1). The rank order of potency (C4 (compound 4) > C3 (compound 3) > or = C2 (compound 2) = C5 (compound 5) = C6 (compound 6) >> compound 1) was similar at each VGSC. Compound 4 exhibited strong use-dependent inhibition of hNa(v)1.5 with pIC50 values < 4.5 and 6.0 for tonic and phasic block, respectively. Coincubation with local anesthetics but not tetrodotoxin attenuated compound 4-mediated inhibition of hNa(v)1.5. These data suggest that the compound 4 binding site(s) is identical, or allosterically coupled, to the local anesthetic receptor. The dissociation rate of the dimers from hNa(v)1.5 was dependent upon the linker length, with a rank order of compound 1 > compound 5 = compound 6 > compound 2 >> compound 3. The observation that both the potency and dissociation rate of the dimers was dependent upon linker length is consistent with a multivalent interaction at VGSCs. hNa(v)1.5 VGSCs did not recover from inhibition by compound 4. However, "chase" with free local anesthetic site inhibitors increased the rate of dissociation of compound 4. Together, these data support the hypothesis that compound 4 simultaneously occupies two binding sites on VGSCs, both of which can be bound by known local anesthetic site inhibitors.

Implantable cardioverter defibrillator in a 4-month-old infant with cardiac arrest associated with a vascular heart tumor

A previously healthy male infant was resuscitated after spontaneous ventricular fibrillation at 9 weeks of age. Echocardiography revealed three tumors in the left ventricle not amenable to complete resection. Despite treatment with antiarrhythmic agents the ventricular arrhythmias continued. When the child was 4 months old and weighed 7 kg an ICD system was implanted using epicardial sense-pacing leads and a superior vena caval lead as a subcutaneous defibrillator coil placed posterior on the left thorax. Shocks were delivered between the subcutaneous coil lead and the intraabdominally placed ICD can. This ICD array system has not been reported previously.

Screening for mutations and polymorphisms in the genes KCNH2 and KCNE2 encoding the cardiac HERG/MiRP1 ion channel: implications for acquired and congenital long Q-T syndrome

BACKGROUND

The voltage-gated, rapid-delayed rectifier current (I(Kr)) is important for repolarization of the heart, and mutations in the genes coding for the K+-ion channel conducting this current, i.e., KCNH2 for the alpha-subunit HERG and KCNE2 for the beta-subunit MiRP1, cause acquired and congenital long Q-T syndrome (LQTS) and other cardiac arrhythmias.

METHODS

We developed a robust single-strand conformation polymorphism-heteroduplex screening analysis, with identical thermocycling conditions for all PCR reactions, covering all of the coding exons in KCNH2 and KCNE2. The method was used to screen 40 unrelated LQTS patients.

RESULTS

Eleven mutations, of which six were novel, were found in KCNH2. Interestingly, six mutations were found in the region of the gene coding for the Per-Arnt-Sim (PAS) and PAS-S1 regions of the HERG protein, stressing the need to examine the entire gene when screening for mutations. No mutations were found in KCNE2, suggesting that direct involvement of MiRP1 in LQTS is rare. Furthermore, four novel single-nucleotide polymorphisms (SNPs) and one amino acid polymorphism (R1047L) were identified in KCNH2, and one novel SNP and one previously known amino acid polymorphism (T8A) were found in KCNE2.

CONCLUSIONS

The potential role of rare polymorphisms in the HERG/MiRP1 K+-channel should be clarified with respect to drug interactions and susceptibility to arrhythmia and sudden death.

Tolerance and specificity of polyketide synthases

Polyketide synthases catalyze the assembly of complex natural products from simple precursors such as propionyl-CoA and methylmalonyl-CoA in a biosynthetic process that closely parallels fatty acid biosynthesis. Like fatty acids, polyketides are assembled by successive decarboxylative condensations of simple precursors. But whereas the intermediates in fatty acid biosynthesis are fully reduced to generate unfunctionalized alkyl chains, the intermediates in polyketide biosynthesis may be only partially processed, giving rise to complex patterns of functional groups. Additional complexity arises from the use of different starter and chain extension substrates, the generation of chiral centers, and further functional group modifications, such as cyclizations. The structural and functional modularity of these multienzyme systems has raised the possibility that polyketide biosynthetic pathways might be rationally reprogrammed by combinatorial manipulation. An essential prerequisite for harnessing this biosynthetic potential is a better understanding of the molecular recognition features of polyketide synthases. Within this decade, a variety of genetic, biochemical, and chemical investigations have yielded insights into the tolerance and specificity of several architecturally different polyketide synthases. The results of these studies, together with their implications for biosynthetic engineering, are summarized in this review.

Long QT syndrome with a high mortality rate caused by a novel G572R missense mutation in KCNH2

In a four-generation family with long QT syndrome, syncopes and torsades de pointes ventricular tachycardia (TdP) were elicited by abrupt awakening in the early morning hours. The syndrome was associated with a novel KCNH2 missense mutation, G572R, causing the substitution of a glycine residue at position 572, at the end of the S5 transmembrane segment of the HERG K(+)-channel, with an arginine residue. This segment is involved in the channel pore and the mutation may cause a reduction in the rapidly activating delayed rectifier K+ current (Ikr), or changed gating properties of the ion channel, leading to prolonged cardiac repolarization. The electrocardiograms of affected persons showed prolonged QT interval and notched T waves. Despite treatment with atenolol, 200 mg twice daily, the proband still experienced TdP episodes. Three untreated relatives of the proband died suddenly, and unexpectedly, at 18, 32, and 57 years of age. The G572R mutation is thus associated with a high mortality rate, and the clinical presentation illustrates that some mutations may not be controllable by just beta-blockade.

A single strand conformation polymorphism/heteroduplex (SSCP/HD) method for detection of mutations in 15 exons of the KVLQT1 gene, associated with long QT syndrome

Congenital long QT syndrome (LQTS) is characterised by prolongation of the QT interval on ECG and cardiac arrhythmias, syncopes and sudden death. A rapid and reliable genetic diagnosis of the disease may be of great importance for diagnosis and treatment of LQTS. Mutations in the KVLQT1 gene, encoding a potassium-channel subunit of importance for the depolarisation of cardiac myocytes, is believed to be associated with 50% of all LQTS cases. Our data confirms that KvLQT1 isoform 1 is encoded by 16 exons, and not 15, as reported previously. We have used genomic DNA sequences to design intronic PCR primers for amplification of 15 exons of KVLQT1 and optimised a non-radioactive single stranded conformation polymorphism/heteroduplex (SSCP/HD) method for detection of mutations in KVLQT1. The sensitivity of the method was 100% when it was tested on 15 in vitro constructed mutants. By multiplexing the PCR amplification of KVLQT1, it is possible to cover all 15 exons in four PCR reactions.

Precursor-directed biosynthesis of 12-ethyl erythromycin

A precursor-directed method for the biosynthesis of novel 6-deoxyerythronolide B derivatives has been extended to allow alteration of the functionality at C-12. We recently described a simple and practical method for harnessing the biosynthetic potential of the erythromycin pathway to generate novel molecules of natural product-like complexity by feeding designed synthetic molecules to an engineered mutant strain having an altered 6-deoxyerythronolide B synthase (DEBS). Our initial applications of this technique focused on alteration of the ethyl side chain of 6-dEB (C14-C15). We now report the extension of this approach to modification of the C-12 substituent. An appropriately designed substrate is shown to incorporate into 6-dEB biosynthesis, yielding a 6-dEB analogue bearing a 12-ethyl group. This 6-dEB analogue is a substrate for post-polyketide tailoring enzymes, and is converted into the corresponding analogue of erythromycin C. These results show that many of the downstream active sites are tolerant of this unnatural functionality and suggest that a wide variety of erythromycin derivatives should be accessible by this approach or by total biosynthesis via genetic engineering.

Spontaneous priming of a downstream module in 6-deoxyerythronolide B synthase leads to polyketide biosynthesis

Modular polyketide synthases such as 6-deoxyerythronolide B synthase (DEBS) catalyze the biosynthesis of structurally complex natural products by repetitive condensation of simple carboxylic acid monomers. The synthase can be divided into groups of domains, called "modules", each of which is responsible for one cycle of chain extension and processing. The modular nature of these enzymes suggests that the biosynthetic pathway might be rationally reprogrammed by manipulation of synthases at the domain level. Although, several examples of successful engineering of DEBS have been reported, a critical issue which has not been well-studied is the tolerance of "downstream" active sites to nonnatural substrates. Here, we report that the terminal modules of DEBS, which normally process highly functionalized intermediates, are competent to carry out their natural functions on smaller, more simple substrates. Expressed in the absence of other DEBS proteins, the DEBS3 protein, which normally carries out the final two extension cycles in the synthesis of 6-deoxyerythronolide B (6-dEB), is spontaneously primed with a C3 carboxylic acid. This substrate is then extended through two condensation cycles to form a triketide. Tolerance of the "shortened" intermediates in the biosynthesis of this triketide, in combination with results reported elsewhere [Jacobsen, J. R., Hutchinson, C. R., Cane, D. E., and Khosla, C. (1997) Science 277, 367-369], suggests that relaxed substrate specificity may be a common feature of modular polyketide synthases. Interestingly, priming of DEBS3 appears to proceed, not by acyltransfer from propionyl-CoA, but by decarboxylation of an enzyme-bound methylmalonyl extender unit. This is the second example of decarboxylative priming within DEBS [see also Pieper, R., Gokhale, R. S., Luo, G., Cane, D. E., and Khosla, C. (1997) Biochemistry 36, 1846-1851] and suggests that, in the absence of an acceptable primer (or transferred intermediate), decarboxylative priming of ketosynthase domains may be a general property of modular polyketide synthases.

Relationship between cumulative anthracycline dose and late cardiotoxicity in childhood acute lymphoblastic leukemia

PURPOSE

Late anthrocycline cardiotoxicity after treatment for childhood cancer is common and often progressive. A safe anthracycline dose that will not result in late cardiac abnormalities has not been established due to the limited dose ranges used in existing studies.

PATIENTS AND METHODS

To determine the relationship between cumulative anthracycline dose and late cardiotoxicity, we performed echocardiograms on 189 survivors of childhood acute lymphoblastic leukemia a median of 8.1 years (range, 2.0 to 23.4) after completion of anthracycline therapy. Patients were treated according to protocols that used widely varying cumulative anthracycline doses, but comparable nonanthracycline chemotherapy. Patients were divided into four groups based on the city of treatment and cumulative anthracycline dose: Copenhagen, 0 to 23 mg/m2 (n = 32); Boston, 45 mg/m2 (n = 17); Copenhagen, 73 to 301 mg/m2 (n = 53); and Boston, 244 to 550 mg/m2 (n = 87). Left ventricular dimension and fractional shortening were adjusted for sex and age or body-surface area through use of a control population (n = 296), and then compared among the four groups.

RESULTS

Mean left ventricular dimension was significantly increased in the high-dose Boston group (observed:predicted value, 4.57 cm:4.45 cm; P = .002) and significantly higher than in the two Copenhagen groups. In the three lower-dose groups, there was no significant increase in mean left ventricular dimension, and the groups were not significantly different from each other. Similarly, the mean left ventricular fractional shortening was significantly depressed in the high-dose Boston group (observed:predicted value, 29.0%:33.8%; P = .0001) and significantly lower than in the three lower-dose groups.

CONCLUSION

Depressed left ventricular fractional shortening and left ventricular dilatation were uncommon years after treatment of childhood leukemia when cumulative anthracycline doses were < or = 300 mg/m2.

New directions in metabolic engineering

Metabolic engineering is a rapidly evolving field. The term typically refers to the genetic modification of cellular biochemistry to introduce new properties or modify existing ones. Recent progress in genetics, molecular biology, microbiology and chemistry are driving advances in this field. Many well-studied areas continue to yield exciting results and new problems and technologies are constantly being developed.

Molecular recognition of diketide substrates by a beta-ketoacyl-acyl carrier protein synthase domain within a bimodular polyketide synthase

BACKGROUND

Modular polyketide synthases (PKSs) are large multifunctional proteins that catalyze the biosynthesis of structurally complex bioactive products. The modular organization of PKSs has allowed the application of a combinatorial approach to the synthesis of novel polyketides via the manipulation of these biocatalysts at the genetic level. The inherent specificity of PKSs for their natural substrates, however, may place limits on the spectrum of molecular diversity that can be achieved in polyketide products. With the aim of further understanding PKS specificity, as a route to exploiting PKSs in combinatorial synthesis, we chose to examine the substrate specificity of a single intact domain within a bimodular PKS to investigate its capacity to utilize unnatural substrates.

RESULTS

We used a blocked mutant of a bimodular PKS in which formation of the triketide product could occur only via uptake and processing of a synthetic diketide intermediate. By introducing systematic changes in the native diketide structure, by means of the synthesis of unnatural diketide analogs, we have shown that the ketosynthase domain of module 2 (KS2 domain) in 6-deoxyerythronolide B synthase (DEBS) tolerates a broad range of variations in substrate structure, but it strongly discriminates against some others.

CONCLUSIONS

Defining the boundaries of substrate recognition within PKS domains is crucial to the rationally engineered biosynthesis of novel polyketide products, many of which could be prepared only with great difficulty, if at all, by direct chemical synthesis or semi-synthesis. Our results suggest that the KS2 domain of DEBS1 has a relatively relaxed specificity that can be exploited for the design and synthesis of medicinally important polyketide products.

Double-homograft repair of truncus arteriosus with severe truncal valve dysfunction

An infant with truncus arteriosus and severe dysfunction of the truncal valve including both stenosis and insufficiency successfully underwent primary repair. This included the insertion of two separate valved homograft conduits. Early outcome has been excellent and the patient is doing well after 6 months with only echocardiographic evidence of mild aortic valve regurgitation. Double-homograft repair is a realistic option in cases of truncus arteriosus with severe malformation of the truncal valve.

Precursor-directed biosynthesis of erythromycin analogs by an engineered polyketide synthase

A genetic block was introduced in the first condensation step of the polyketide biosynthetic pathway that leads to the formation of 6-deoxyerythronolide B (6-dEB), the macrocyclic precursor of erythromycin. Exogenous addition of designed synthetic molecules to small-scale cultures of this null mutant resulted in highly selective multimilligram production of unnatural polyketides, including aromatic and ring-expanded variants of 6-dEB. Unexpected incorporation patterns were observed, illustrating the catalytic versatility of modular polyketide synthases. Further processing of some of these scaffolds by postpolyketide enzymes of the erythromycin pathway resulted in the generation of novel antibacterials with in vitro potency comparable to that of their natural counterparts.

One-stage repair of truncus arteriosus, CAVC, and TAPVC

An infant with truncus arteriosus, complete atrioventricular canal, and total anomalous pulmonary venous connection successfully underwent one-stage complete repair. Residual mitral valve regurgitation required reoperation after 12 days. The patient is doing well at 6 months' follow-up. Echocardiography demonstrates no residual defects, competent atrioventricular valves, and normal pulmonary pressure. This case illustrates the potential for successful one-stage repair even of associated complex heart defects involving venous, intracardiac, and arterial pathways.

Early experience with the Norwood procedure

The improved results of the Norwood procedure have recently stimulated its widespread adoption in many centres. Since 1993, 19 infants with hypoplastic left heart syndrome or similar conditions underwent a first-stage Norwood procedure. Circulatory arrest time was significantly reduced by using a modified repair of the aortic arch. The early mortality rate was 31.5% (n = 6). The addition of CO2 to the inspired gas mixture resulted in less early postoperative instability. Nine patients have subsequently undergone bidirectional cavopulmonary shunt and one fenestrated total cavopulmonary connection. Overall there have been five late deaths, two as result of failure of cavopulmonary operations. All the eight survivors are presently in good condition. One is awaiting bidirectional cavopulmonary shunt and the other seven total cavopulmonary connection. This early experience encourages the continued offering of the Norwood procedure to patients with hypoplastic left heart syndrome or its variants. Increasing experience with the perioperative care and a more careful evaluation before cavopulmonary operations may determine further improvement in the outcome.

Is the arterial switch operation still a challenge in small centers?

OBJECTIVE

In the last years, major changes as regards timing for operation, surgical technique, and perioperative care determined a great improvement in the arterial switch operation (ASO) allowing excellent mid-term results in a few leading centers. This stimulated the widespread adoption of ASO as procedure of choice for transposition of the great arteries (TGA), even in small institutions. We reviewed our early experience with ASO in an attempt to evaluate its safety in a small center.

METHODS

Since April 1992, 39 consecutive patients underwent TGA repair by ASO in our department. There were 27 patients with simple TGA, 8 with TGA and VSD and 4 with Taussig-Bing heart and aortic coarctation. Median age and weight at operation were 7 days and 3.5 kg, respectively. Neonatal repair was performed in 34 patients. In accordance with the Planché coronary classification, type I was encountered in 21 patients, type II in 4 and type III in 14. Several modifications of the original technique were used, mainly regarding coronary relocation, pulmonary artery reconstruction and approaches for associated VSD closure and aortic arch repair.

RESULTS

Early mortality was 2.6% (n = 1), the only operative death being related to unsatisfactory coronary relocation. Since modified ultrafiltration was adopted, mean ICU stay decreased from 5 +/- 4 days (n = 21) to 2 +/- 1 days (n = 17) (P < 0.05). Three patients required reoperation for residual ASD and/or VSD closure. There were no late deaths. After a mean follow-up of 26 +/- 15 months all survivors are thriving and are currently asymptomatic.

CONCLUSIONS

Although this series is rather small, most of the major coronary anomalies and complex anatomic associations were encountered. This experience suggests that neonatal repair of TGA by ASO can be safely accomplished even in small centers. Modified ultrafiltration appears to improve the early outcome of neonates undergoing ASO.

A functional chimeric modular polyketide synthase generated via domain replacement

BACKGROUND

Modular polyketide synthases (PKSs), such as 6-deoxyerythronolide B synthase (DEBS), are large multifunctional enzymes that catalyze the biosynthesis of structurally complex and medically important natural products. Active sites within these assemblies are organized into 'modules', such that each module catalyzes the stereospecific addition of a new monomer onto a growing polyketide chain and also sets the reduction level of the beta-carbon atom of the resulting intermediate. The core of each module is made up of a 'reductive segment', which includes all, some, or none of a set of ketoreductase (KR), dehydratase, and enoylreductase domains, in addition to a large interdomain region which lacks overt function but may contribute to structural stability and inter-domain dynamics within modules. The highly conserved organization of reductive segments within modules suggests that they might be able to function in unnatural contexts to generate novel organic molecules.

RESULTS

To investigate domain substitution as a method for altering PKS function, a chimeric enzyme was engineered. Using a bimodular derivative of DEBS (DEBS1+TE), the reductive segment of module 2, which includes a functional KR, was replaced with its homolog from module 3 of DEBS, which contains a (naturally occurring) nonfunctional KR. A recombinant strain expressing the chimeric gene produced the predicted ketolactone with a yield (35 %) comparable to that of a control strain in which the KR2 domain was retained but mutationally inactivated.

CONCLUSIONS

These results demonstrate considerable structural tolerance within an important segment found in virtually every PKS module. The domain boundaries defined here could be exploited for the construction of numerous loss-of-function and possibly even gain-of-function mutants within this remarkable family of multifunctional enzymes.

The scope of antibody catalysis

New strategies for hapten design have led to antibodies that catalyze reactions by increasingly complex mechanisms and with large increases in catalytic rate. Rational design has also been used to elicit catalytic antibodies for difficult chemical transformations as well as reactions for which no enzyme is known. These experiments have demonstrated the chemical potential of large combinatorial libraries that have been given appropriate mechanistic instruction.

Perinatal outcome after in vitro fertilisation

A prospective series of 90 consecutive pregnancies (70 singleton, 16 twin and 4 triplet pregnancies) resulting in births of 114 infants after in vitro fertilisation (IVF) at Rigshospitalet were compared to a control group of pregnancies and deliveries in 70 non-IVF infertility patients with singleton pregnancies and 20 women with normal fertility with twin (n = 16) or triplet (n = 4) pregnancies. No differences in the incidence of third trimester pregnancy complications, abnormal fetal karyotypes or malformations were found. The number of women with spontaneous onset of labor and the gestational age at delivery were similar in the IVF and control groups. In singleton deliveries, the birth weight was lower (p < 0.025) in the IVF group (median 3145 g, range 890-4300 g) than in the control group (3399 g, 2592-4850 g), whereas in multiple gestation similar birth weights were found in the IVF and control groups. We conclude that the birth weight in singleton deliveries after IVF is lower than the birth weight in infertility patients treated differently. The cause of this difference remains obscure.

[Kawasaki disease. Incidence in Denmark during the period 1981-1990]

The aim of the study was to estimate the incidence of Kawasaki's disease and to describe the clinical manifestations and the prognosis of the disease in children in Denmark during the period 1981-1990. In a register of all hospital admissions in Denmark, 99 patients were registered as having Kawasaki's disease. Of those, 89 patients fulfilled the clinical diagnostic criteria. The mean incidence of the ten year period was 1.0 per 100,000 children per year. The incidence of the disease decreased in the age group from zero to seven years after which it was rarely observed. Typical laboratory findings were hypersedimentation, leucocytosis and thrombocytosis. Eight children had cardiomegaly and three had electrocardiographic changes. Echocardiography was performed in 66 patients showing coronary artery aneurysms in nine patients (14%) (six boys and three girls). No further cardiac complications were found.

True trisomy 15 mosaicism, detected by amniocentesis at 12 weeks of gestation and fetal echocardiography

A case of mosaicism of trisomy 15, with two-thirds of the cells trisomic, was detected at 12 weeks of gestation in amniotic fluid cell cultures obtained with the filtration technique. Ultrasound examination at 13 weeks showed a nodule protruding into the amniotic cavity which was speculated to be remnants of a co-twin, causing the trisomic cell line. At 20 weeks of gestation, a malformation scan (level III) was normal, but supplementary fetal echocardiography revealed a severe cardiac defect (mitral atresia and a ventricular septal defect). Fetal lymphocytes obtained by cordocentesis showed trisomy 15 mosaicism, but only in 5 per cent of the mitoses. After termination, the same percentage of trisomy 15 mosaicism was found in cells from skin and tendon as in the original early amniocentesis. No sign of earlier twinning was found in the placenta or membranes. We conclude that mosaicism in early amniotic fluid obtained by the filter technique in this case reflected the true karyotype accurately and that supplementary echocardiography added significantly to the interpretation of the clinical implications.

Antibody catalysis of peptide bond formation

An antibody generated against a neutral phosphonate diester transition-state (TS not equal to) analog catalyzes the formation of an amide bond between a phenylalanyl amino group and an acyl azide derived from L-alanine. The antibody is selective for L- vs. D-alanine and does not catalyze the hydrolysis of the acyl azide to an appreciable degree. A rate acceleration of 10,000-fold relative to the uncatalyzed reaction is observed. The antibody may achieve its catalytic efficiency both by acting as an entropy trap and by stabilizing the deprotonated form of the amine nucleophile. These experiments constitute a first step toward a general strategy for the generation of sequence-specific peptide ligases.

Fluorescence probes in biochemistry: an examination of the non-fluorescent behavior of dansylamide by photoacoustic calorimetry

Photoacoustic calorimetry is shown to be a simple, precise, and accurate method for the quantification of the photophysics of a fluorescence probe, e.g., dansylamide, in a variety of solvents. This technique, which is described in detail, provides a direct measurement of the energy that is released nonradiatively following photostimulation, and can therefore be used to indirectly determine the amount of energy released via luminescent pathways. Photoacoustic calorimetry combined with established absorption and fluorescence methodologies provides a complete arsenal for characterizing the photophysical properties of many systems. Comparison of the photoacoustic signal for dansylamide versus standard compounds (ferrocene, tetraphenylethylene, 8-anilinonaphthalene-1-sulfonate, and/or 5,5'-dithiobis(2-nitrobenzoic acid) in 12 different solvents gave fh values (fraction of each absorbed 337.1-nm photon returned as heat) from a low of 0.530 in 1,4-dioxane to a high of 0.973 in water. The trend noted with solvent polarity is different and more revealing than that determined by the more classical approach of examining either the wavelength of the emission maximum or the fluorescence quantum yield.

Aneurysm of the ductus arteriosus in the neonate: three case reports with a review of the literature

Ductus arteriosus aneurysm was demonstrated in three neonates by echocardiography. One case was already diagnosed in utero. One patient needed surgical resection, whereas in one case the aneurysm of the ductus arteriosus regressed spontaneously. In the third case the patient died of associated lesions. In a review of the literature, 61 previous cases of ductus aneurysm in infants less than 2 months were found. Ductus arteriosus aneurysm may be diagnosed by echocardiography both pre- and postnatally. A ductus aneurysm should be monitored closely by echocardiography. Since a high incidence of complications is reported, surgical resection is indicated if the aneurysm does not regress within a few days.

Bacterial endocarditis in children: trends in its diagnosis, course, and prognosis

In a population-based study of 41 children with bacterial endocarditis (BE), diagnosed in the period 1970 through 1989 in eastern Denmark, we analyzed trends in the diagnosis of BE and in mortality, and searched for possible prognostic factors. During this period the delay in diagnosis from first symptom to treatment did not change, but the delay from admission to treatment was significantly prolonged from 0 to 3 days, despite the introduction of echocardiography (ECHO). There was a significant improvement in the prognosis, the mortality rate having decreased from 40 to 0% [95% confidence limits: 12-74 vs. 0-26 (0.01 less than p less than 0.02)]. The improved prognosis was not explained by changes in the etiology or pattern of antibiotic resistance and may reflect a milder course of BE in children. Children with "mild anomalies"--such as bicuspid aortic valve (n = 5), coarctation of the aorta (n = 2), and prolapse of the mitral valve (n = 2)--had a significantly poorer prognosis than children with other forms of congenital heart disease (CHD) (p = 0.004), a reminder of the importance of suspecting BE in all children with unexplained long-lasting or intermittent fever, because some may have unrecognized "mild" CHD.

An efficient antibody-catalyzed aminoacylation reaction

An antibody generated against a neutral phosphonate diester transition-state analog was found to catalyze the aminoacylation of the 3'-hydroxyl group of thymidine with an alanyl ester. A comparison of the apparent second-order rate constant of the antibody-catalyzed reaction [5.4 x 10(4) molar-1 minute-1 (M-1 min-1)] with that of the uncatalyzed reaction (2.6 x 10(-4) M-1 min-1) revealed this to be a remarkably efficient catalyst. Moreover, although the concentration of water (55 M) greatly exceeds that of the secondary alcohol, the antibody selectively catalyzes acyl transfer to thymidine. The antibody exhibits sequential binding, with Michaelis constants of 770 microM and 260 microM for acyl acceptor and donor, respectively, and a dissociation constant of 240 pM for hapten. This antibody-catalyzed reaction provides increased insight into the requirements for efficient aminoacylation catalysts and may represent a first step toward the generation of "aminoacyl transfer RNA synthetases" with novel specificities.

[Percutaneous pulmonary balloon valvuloplasty in Denmark]

Percutaneous balloon valvuloplasty of valvular pulmonary stenosis (PPB) was carried out for the first time in 1982 and is now regarded as the primary method of treatment of this condition. The results of the first PPB treatments in Denmark are presented here. PPB was planned in 28 patients and was carried out in 25 (22 children and 3 adults). PPB was carried out on two occasions in one patient. Twenty-three patients had isolated valvular pulmonary stenosis and two patients had Fallot's anomaly. No complications of significance occurred after the treatments. The average gradient for all dilatations was 77 +/- 24 mm Hg prior to and 36 +/- 23 (p less than 0.0001) immediately after PPB. The gradient was reduced by more than 50% in 68% of the patients. In 14 patients, the gradients over the pulmonary valve was measured by Doppler technique or by cardiac catheterization greater than 6 months after PPB. In these patients, the average gradient was 69 +/- 21 mm Hg prior to PPB, 29 +/- 12 mm Hg (p less than 0.0001) immediately after PPB and 27 +/- 9 mm Hg (p less than 0.0001) at the most recent control examination, on an average 12 months (range 6-24 months) after PPB. In the same patient group, significant reduction of the electrocardiographic right-sided hypertrophy was found at the most recent control examination. It is concluded that PPB is an effective and safe treatment of valvular pulmonary stenosis.

[Prenatal detection of congenital heart disease]

Foetal echocardiography is a sensitive and specific method of investigation for prenatal detection of cardiac malformations. Experience has shown that brief echocardiographic screening can demonstrate, directly or indirectly, the presence of or probability of serious cardiac disease in the foetus as early as the 18th-20th weeks of pregnancy. The method of examination and its limitations are mentioned and it is recommended that screening should be carried out as part of other forms of obstetric ultrasonic scanning. Early prenatal diagnosis of severe structural cardiac malformations provide the possibility for selective termination of pregnancy, optimal pre- and perinatal observation and treatment. The possibility of prenatal diagnosis of serious cardiac malformations increases the value of obstetric ultrasonic scanning and may be included among the advantages of offering this form of investigation to all pregnant women.

[In vitro fertilization and embryo transfer. 2. The first 44 deliveries of 55 infants]

During the period 1.9.1985-21.2.1988, 143 patients commenced and completed treatment with in vitro fertilization and embryo-transfer (IVF-ET) in Rigshospitalet, Copenhagen. Forty-four out of the 143 patients were delivered of a total of 55 infants. There were 35 single deliveries, seven twin deliveries and two triplet deliveries. Seven women were admitted with threatened abortion and three women developed preeclampsia, one of these was severe. On an average, the deliveries occurred in the 38th week of pregnancy and the average weight of the singletons was 3,020 g. Ten women were delivered preterm and seven of the singletons had birth weights under 2,500 g. The frequency of caesarean section was 34% for singleton deliveries and 43% for all of the deliveries. Thirty-one boys and 24 girls were delivered, all of whom had normal karyotypes. One infant had a cleft lip but no other malformations. Three premature infants required brief respirator treatment. All of the infants were thriving on discharge. This material is still too limited to permit drawing of definite conclusions but it suggests, however, just as in other IVT-ET investigations, that the infants are born slightly earlier and weigh slightly less than average neonates, but that they are otherwise normal. In order to illustrate these problems further, the authors have commenced a more extensive prospective investigation with matched control persons.

[Pulmonary hypertension in children treated with ventriculo-atrial shunt in hydrocephalus]

Four infants treated with ventriculo-atrial shunt for hydrocephalus developed sudden pulmonary hypertension, several years after the first operation. All infants died in spite of replacement of the distal shunt and AK treatment. At necropsy, old microemboli were found in the small lung vessels in two infants whereas the two other infants were suspected of having the same lesions from clinical investigations. The overall frequency for this complication was estimated to be 6.7% (95% CI 1.4-14.3%).

Long-term follow-up of right ventricular function after Mustard operation for transposition of the great arteries

As development of right ventricular (RV) failure is a potential risk after Mustard operation for transposition of the great arteries, 17 patients were reexamined 5-13 years postoperatively. Comparisons were made with healthy controls. There were no clinical signs of heart failure. Echocardiographically determined RV end-diastolic diameter was increased to 2.5 +/- 0.8 cm (controls: 1.5 +/- 0.4 cm, p less than 0.001). Comparison of RV systolic time intervals (STI) in patients with normal left ventricular (LV) STI revealed decreased RV function, with RPEPI 165 +/- 19 msec (controls 126 +/- 12, p less than 0.001) and RPEP/RVET 0.484 +/- 0.096 (controls 0.284 +/- 0.045, p less than 0.001). Nuclear angiography demonstrated decreased RV ejection fraction (EF), viz. 42.8 +/- 6.6% (normal RV 53 +/- 6%, LV 68 +/- 9%, p less than 0.001). Only two patients showed normal (5%) rise in RV-EF during exercise. There was no evidence of deterioration with passage of time. The results do not justify use of anatomic repair at our center, since the perioperative mortality might then be higher than in the Mustard or Senning procedures.

Assessment of rheumatic mitral valve disease. Value of echocardiography in patients clinically suspected of predominant stenosis

The value of echocardiography as compared with cardiac catheterisation was evaluated prospectively in 33 consecutive patients clinically suspected of predominant mitral stenosis. Patients with clinical signs of accompanying mitral regurgitation, no matter how severe, and patients with clinical findings indicating insignificant aortic valve disease were included. Critical mitral stenosis was defined by a valve area of less than or equal to 1 cm2. Severe mitral regurgitation was diagnosed by echocardiography on the basis of left ventricular dilatation (more than 3.2 cm/m2 at end-diastole) if not explained otherwise. Significant aortic valve disease was suspected in cases with aortic valve deformity and left ventricular dilatation or hypertrophy as defined by echocardiography. Mitral valve area by echocardiography correlated well with mitral valve area calculated from catheterisation data and a good interobserver correlation was found for echocardiographic measurement. Mitral stenosis, critical or non-critical, may mask significant coexistent valve lesions; echocardiography failed to discover severe mitral regurgitation requiring valve replacement in two patients with non-critical stenosis, and significant aortic regurgitation needing valve replacement was underestimated in one patient with critical mitral stenosis. A correct echocardiographic classification with respect to surgery, however, was obtained in: (1) all patients with clinically pure mitral stenosis (nine patients), and (2) all patients with combined mitral stenosis and regurgitation when either critical stenosis or severe regurgitation was found at echocardiography (12 patients). It thus appears that two out of three patients with mitral valve disease in whom the clinical findings indicate predominant stenosis can be correctly evaluated with the echocardiogram.

Coarctation of the aorta operated upon in infancy. Long-term follow-up

A long-term follow-up study was performed in 14 patients, operated for coarctation of the aorta in infancy. The median age at operation was 4 mth. Mean and median age at follow-up were 16 yr, and the follow-up time varied between 7 and 22 yr (mean and median 15 yr). At follow-up recoarctation was or had been present in 6 patients; there was no relation between the development of recoarctation and the age at operation. Concomitant aortic valve anomaly had been overlooked at the initial investigation in 3 patients. The systolic and diastolic blood pressure at follow-up was significantly elevated above the mean of normals; 2 of 8 patients without recoarctation clearly had diastolic hypertension. It seems as if even operation in infancy does not prevent hypertension later in childhood or adolescence in some of the patients, and it hardly seems justified to perform elective operations for coarctation of the aorta in infancy with the appreciable risk of recoarctation, until more long-term follow-up results are known. The patients should not be lost to follow-up.

Dosage of digoxin in premature infants

The pharmacokinetics and pharmacodynamics of digoxin in premature infants was studied. During maintenance therapy, after a total digitalizing dose of 30 microgram/kg, the measured digoxin level was related inversely to body weight at birth and to estimated gestational age. The serum digoxin levels found in the immature and smaller infants were two to three times the values usually reported to be toxic in older children. Based on these findings, a second group of premature infants was digitalized with 20 microgram/kg; in this group, the serum digoxin levels were below the toxic range, irrespective of gestational age or birth weight. The cardiac effects of digoxin, i.e., shortened left ventricular pre-ejection period and ejection time as determined by echocardiography, were similar in the two groups. For both groups, the half-life of digoxin in the serum was twice that reported for term infants and children. Since digitalis effect is obtained with lower dose and serum concentration, we recommend that this dose be used in premature infants.

Cervical aortic arch with ventricular septal defect. A differential diagnosis from interrupted aortic arch

A case of right cervical aortic arch with a large ventricular septal defect and a bicuspid aortic valve is reported. The angiographic diagnosis was interruption of the aortic arch type II, with aberrant right subclavian artery, a closed ductus arteriosus and retrograde vertebral-subclavian flow to the descending aorta. The cervical arch, demonstrated post mortem, was located high and deep in the neck. This differential diagnosis may have potential importance, as reported experience shows that a surgical aortic anastomosis is not required in cervical aortic arch.

Natural history of valvular pulmonary stenosis in children below the age of two years. Long-term follow-up with serial heart catheterizations

18 patients with mild and moderate valvular pulmonary stenosis diagnosed by heart catheterization before the age of 2 yr (mean 11.6 mth) were followed for 5 to 21 yr without operation. 15 cases had a repeat catheterization study after a mean interval of 10.7 yr. Of 7 cases with an initial right ventricular peak systolic pressure (RVSP) of 50 mm Hg or below, 6 had a decrease and 1 a moderate increase in RVSP. Of 8 cases with an initial RVSP of greater than 50 mm Hg 2 had a decrease, 2 had no change and 4 had a significant increase in RVSP; the latter subsequently underwent operation. Electrocardiography yielded some information, but neither roentgenography nor history was of any help in evaluating the severity of the stenosis at follow-up. As mild and moderate valvular pulmonary stenosis in infants and children below the age of 2 may progress and require operation a repeat heart catheterization is usually to be recommended later in childhood.