Multigene phylogenetics of euglenids based on single-cell transcriptomics of diverse phagotrophs

Euglenids are a well-known group of single-celled eukaryotes, with phototrophic, osmotrophic and phagotrophic members. Phagotrophs represent most of the phylogenetic diversity of euglenids, and gave rise to the phototrophs and osmotrophs, but their evolutionary relationships are poorly understood. Symbiontids, in contrast, are anaerobes that are alternatively inferred to be derived euglenids, or a separate euglenozoan group. Most phylogenetic studies of euglenids have examined the SSU rDNA only, which is often highly divergent. Also, many phagotrophic euglenids (and symbiontids) are uncultured, restricting collection of other molecular data. We generated transcriptome data for 28 taxa, mostly using a single-cell approach, and conducted the first multigene phylogenetic analyses of euglenids to include phagotrophs and symbiontids. Euglenids are recovered as monophyletic, with symbiontids forming an independent branch within Euglenozoa. Spirocuta, the clade of flexible euglenids that contains both the phototrophs (Euglenophyceae) and osmotrophs (Aphagea), is robustly resolved, with the ploeotid Olkasia as its sister group, forming the new taxon Olkaspira. Ploeotids are paraphyletic, although Ploeotiidae (represented by Ploeotia spp.), Lentomonas, and Keelungia form a robust clade (new taxon Alistosa). Petalomonadida branches robustly as sister to other euglenids in outgroup-rooted analyses. Within Spirocuta, Euglenophyceae is a robust clade that includes Rapaza, and Anisonemia is a well-supported monophyletic group containing Anisonemidae (Anisonema and Dinema spp.), 'Heteronema II' (represented by H. vittatum), and a clade of Neometanema plus Aphagea. Among 'peranemid' phagotrophs, Chasmostoma branches with included Urceolus, and Peranema with the undescribed 'Jenningsia II', while other relationships are weakly supported and consequently the closest sister group to Euglenophyceae remains unresolved. Our results are inconsistent with recent inferences that Entosiphon is the evolutionarily pivotal sister either to other euglenids, or to Spirocuta. At least three transitions between posterior and anterior flagellar gliding occurred in euglenids, with the phylogenetic positions and directions of those transitions remaining ambiguous.

Microsporidia - Emergent Pathogens in the Global Food Chain

Intensification of food production has the potential to drive increased disease prevalence in food plants and animals. Microsporidia are diversely distributed, opportunistic, and density-dependent parasites infecting hosts from almost all known animal taxa. They are frequent in highly managed aquatic and terrestrial hosts, many of which are vulnerable to epizootics, and all of which are crucial for the stability of the animal-human food chain. Mass rearing and changes in global climate may exacerbate disease and more efficient transmission of parasites in stressed or immune-deficient hosts. Further, human microsporidiosis appears to be adventitious and primarily associated with an increasing community of immune-deficient individuals. Taken together, strong evidence exists for an increasing prevalence of microsporidiosis in animals and humans, and for sharing of pathogens across hosts and biomes.

Creatine kinase isoforms as circulating markers of deterioration in idiopathic dilated cardiomyopathy

BACKGROUND

A proportion of patients with dilated cardiomyopathy (DCM) may have ongoing myocardial damage secondary to viral or immune mediated myocardial inflammation.

HYPOTHESIS

The prognostic determinants identify patients with decreased survival but do not provide a measure of myocardial damage. To obtain an objective assessment of myocardial damage in DCM, we measured plasma levels of creatine kinase (CK), its isoenzymes (CK-MM and CK-MB), and separated the isoforms of CK-MM and CK-MB.

METHODS

The cohort consisted of 77 consecutive patients (61 men, 16 women) with DCM (World Health Organization criteria), aged 49 +/- 14 years (range 19-60). Patients had been symptomatic for 29 +/- 38 months (range 0.5-200 months) with 48 in New York Heart Association class I/II and 29 in class III/IV at the time of diagnosis. During median follow-up of 27 months from diagnosis (range 0.6-165), 50 patients remained clinically stable and 27 had deteriorated.

RESULTS

A significantly higher proportion of patients with DCM had abnormal MB2/MB1 ratio compared with normal volunteers (11, 14% vs. 1,1%, p = 0.003). Patients who deteriorated had higher MB2/MB1 ratio, (1.22 +/- 0.62 vs. 0.85 +/- 0.56; p = 0.01), and more frequently had abnormal MB2/ MB1 ratio (8, 30% vs. 3, 6%; p = 0.004) and CK and CK-MM activities (5, 19% vs. 2, 4%; p = 0.03) than those who remained stable. Patients with DCM with high CK-MB activity had 3.13-fold increased odds of sudden death or need for cardiac transplantation (95% confidence interval 1.53-6.40, p = 0.008). Thus, CK measurements, in particular CK-MB isoforms, are markers of myocardial damage in a subset of patients with DCM and could be useful in investigating the possibility of persistent myocardial damage in these patients.

MOLECULAR PHYLOGENY AND SURFACE MORPHOLOGY OF MARINE ASEPTATE GREGARINES (APICOMPLEXA): SELENIDIUM SPP. AND LECUDINA SPP

Many aseptate gregarines from marine invertebrate hosts are thought to have retained several plesiomorphic characteristics and are instrumental in understanding the early evolution of intracellular parasitism in apicomplexans and the phylogenetic position of cryptosporidians. We sequenced the small-subunit (SSU) ribosomal RNA genes from 2 archigregarines, Selenidium terebellae and Selenidium vivax, and 2 morphotypes of the marine eugregarine Lecudina polymorpha. We also used scanning electron microscopy to investigate the surface morphology of trophozoites from Lecudina tuzetae, Monocystis agilis, the 2 species of Selenidium, and the 2 morphotypes of L. polymorpha. The SSU ribosomal DNA sequences from S. vivax and L. polymorpha had long branch lengths characteristic of other gregarine sequences. However, the sequence from S. terebellae was not exceptionally divergent and consistently emerged as 1 of the earliest 'true' gregarines in phylogenetic analyses. Statistical support for the sister relationship between Cryptosporidium spp. and gregarines was significantly bolstered in analyses including the sequence from S. terebellae but excluding the longest branches in the alignment. Eugregarines formed a monophyletic group with the neogregarine Ophryocystis, suggesting that trophozoites with elaborate cortex folds and gliding motility evolved only once. The trophozoites from the 2 species of Selenidium shared novel transverse striations but differed from one another in overall cell morphologies and writhing behavior.

Alpha and beta subunits of pyruvate dehydrogenase E1 from the microsporidian Nosema locustae: mitochondrion-derived carbon metabolism in microsporidia

Microsporidia are highly adapted eukaryotic intracellular parasites that infect a variety of animals. Microsporidia contain no recognisable mitochondrion, but recently have been shown to have evolved from fungi and to possess heat shock protein genes derived from mitochondria. These findings make it clear that microsporidian ancestors were mitochondrial, yet it remains unknown whether they still contain the organelle, and if so what its role in microsporidian metabolism might be. Here we have characterised genes encoding the alpha and beta subunits of pyruvate dehydrogenase complex E1 (PDH, EC 1.2.4.1) from the microsporidian Nosema locustae. All other amitochondriate eukaryotes studied to date have lost the PDH complex and replaced it with pyruvate:ferredoxin oxidoreductase (PFOR). Nevertheless, molecular phylogeny shows that these Nosema enzymes are most closely related to mitochondrial PDH from other eukaryotes, demonstrating that elements of mitochondrial metabolism have been retained in microsporidia, and that PDH has not been wholly lost. However, there is still no evidence for a mitochondrion in microsporidia, and neither PDH subunit is predicted to encode an amino terminal leader sequence that could function as a mitochondrion-targeting transit peptide, raising questions as to whether these proteins function in a relic organelle or in the cytosol. Moreover, it is also unclear whether these proteins remain part of the PDH complex, or whether they have been retained for another purpose. We propose that microsporidia may utilise a unique pyruvate decarboxylation pathway involving PDH, demonstrating once again the diversity of core metabolism in amitochondriate eukaryotes.

Lateral transfer at the gene and subgenic levels in the evolution of eukaryotic enolase

Enolase genes from land plants and apicomplexa (intracellular parasites, including the malarial parasite, Plasmodium) share two short insertions. This observation has led to the suggestion that the apicomplexan enolase is the product of a lateral transfer event involving the algal endosymbiont from which the apicomplexan plastid is derived. We have examined enolases from a wide variety of algae, as well as ciliates (close relatives of apicomplexa), to determine whether lateral transfer can account for the origin of the apicomplexan enolase. We find that lateral gene transfer, likely occurring intracellularly between endosymbiont and host nucleus, does account for the evolution of cryptomonad and chlorarachniophyte algal enolases but fails to explain the apicomplexan enolase. This failure is because the phylogenetic distribution of the insertions--which we find in apicomplexa, ciliates, land plants, and charophyte green algae--directly conflicts with the phylogeny of the gene itself. Protein insertions have traditionally been treated as reliable markers of evolutionary events; however, these enolase insertions do not seem to reflect accurately the evolutionary history of the molecule. The lack of congruence between insertions and phylogeny could be because of the parallel loss of both insertions in two or more lineages, or what is more likely, because the insertions were transmitted between distantly related genes by lateral transfer and fine-scale recombination, resulting in a mosaic gene. This latter process would be difficult to detect without such insertions to act as markers, and such mosaic genes could blur the "tree of life" beyond the extent to which whole-gene lateral transfer is already known to confound evolutionary reconstruction.

Dinoflagellate nuclear SSU rRNA phylogeny suggests multiple plastid losses and replacements

Dinoflagellates are a trophically diverse group of protists with photosynthetic and non-photosynthetic members that appears to incorporate and lose endosymbionts relatively easily. To trace the gain and loss of plastids in dinoflagellates, we have sequenced the nuclear small subunit rRNA gene of 28 photosynthetic and four non-photosynthetic species, and produced phylogenetic trees with a total of 81 dinoflagellate sequences. Patterns of plastid gain, loss, and replacement were plotted onto this phylogeny. With the exception of the apparently early-diverging Syndiniales and Noctilucales, all non-photosynthetic dinoflagellates are very likely to have had photosynthetic ancestors with peridinin-containing plastids. The same is true for all dinoflagellates with plastids other than the peridinin-containing plastid: their ancestors have replaced one type of plastid for another, in some cases most likely through a non-photosynthetic intermediate. Eight independent instances of plastid loss and three of replacement can be inferred from existing data, but as more non-photosynthetic lineages are characterized these numbers will surely grow.

Diplonemid glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and prokaryote-to-eukaryote lateral gene transfer

Lateral gene transfer refers to the movement of genetic information from one genome to another, and the integration of that foreign DNA into its new genetic environment. There are currently only a few well-supported cases of prokaryote-to-eukaryote transfer known that do not involve mitochondria or plastids, but it is not clear whether this reflects a lack of such transfer events, or poor sampling of diverse eukaryotes. One gene where this process is apparently active is glyceraldehyde-3-phosphate dehydrogenase (GAPDH), where lateral transfer has been implicated in the origin of euglenoid and kinetoplastid genes. We have characterised GAPDH genes from diplonemids, heterotrophic flagellates that are closely related to kinetoplastids and euglenoids. Two distinct classes of diplonemid GAPDH genes were found in diplonemids, however, neither class is closely related to any other euglenozoan GAPDH. One diplonemid GAPDH is related to the cytosolic gapC of eukaryotes, although not to either euglenoids or kinetoplastids, and the second is related to cyanobacterial and proteobacterial gap3. The bacterial gap3 gene in diplonemids provides one of the most well-supported examples of lateral gene transfer from a bacterium to a eukaryote characterised to date, and may indicate that diplonemids have acquired a novel biochemical capacity through lateral transfer.

Foraminifera and Cercozoa are related in actin phylogeny: two orphans find a home?

In recent years, the increased sampling of protein-coding genes from diverse eukaryotes has revealed that many aspects of each gene tree are at odds with other phylogenies. This has led to the belief that each gene tree has unique strengths and weaknesses, suggesting that an accurate picture of eukaryotic relationships will be achieved only through comparative phylogeny using several different genes. To this end, actin genes were characterized from two genera of chlorarachniophytes, Chlorarachnion and Lotharella, and three species of the cercomonad flagellate Cercomonas: Phylogenetic trees including these new actin genes confirm the recently proposed relationship between chlorarachniophytes and cercomonads (Cercozoa) and, more importantly, also show a close relationship between Cercozoa and Foraminifera. Both of these are major eukaryotic groups encompassing extremely diverse organisms, yet there is no strong evidence for the evolutionary position of either from morphological or molecular data. The union of Cercozoa and Foraminifera suggested by actin phylogeny represents a novel step in the long process of determining the broad relationships between all major eukaryotic groups.

An evaluation of Hsp90 as a mediator of cortical patterning in Tetrahymena

This study asks two questions: 1) whether Hsp90 is involved in the regulation of cortical patterning in Tetrahymena, and 2) if it is, whether specific defects in this regulation can be attributed to functional insufficiency of the Hsp90 molecule. To address question 1, we compared the effects of a specific inhibitor of Hsp90, geldanamycin, on population growth and on development of the oral apparatus in two Tetrahymena species, T. pyriformis and T. thermophila. We observed that geldanamycin inhibits population growth in both species at very low concentrations, and that it has far more severe effects on oral patterning in T. pyriformis than in T. thermophila. These effects are parallel to those of high temperature in the same two species, and provide a tentative affirmative answer to the first question. To address question 2, we ascertained the base sequence of the genes that encode the Hsp90 molecules which are induced at high temperatures in both Tetrahymena species, as well as corresponding sequences in Paramecium tetraurelia. Extensive comparative analyses of the deduced amino acid sequences of the Hsp90 molecules of the two Tetrahymena species indicate that on the basis of what we currently know about Hsp90 both proteins are equally likely to be functional. Phylogenetic analyses of Hsp90 amino acid sequences indicate that the two Tetrahymena Hsp90 molecules have undergone a similar number of amino acid substitutions from their most recent common ancestor, with none of these corresponding to any known functionally critical region of the molecule. Thus there is no evidence that the Hsp90 molecule of T. pyriformis is functionally impaired; the flaw in the control of cortical patterning is more likely to be caused by defects in mechanism(s) that mediate the response to Hsp90, as would be expected from the "Hsp90 capacitor" model of Rutherford and Lindquist.

Nuclear-encoded, plastid-targeted genes suggest a single common origin for apicomplexan and dinoflagellate plastids

The phylum Apicomplexa encompasses a large number of intracellular protozoan parasites, including the causative agents of malaria (Plasmodium), toxoplasmosis (Toxoplasma), and many other human and animal diseases. Apicomplexa have recently been found to contain a relic, nonphotosynthetic plastid that has attracted considerable interest as a possible target for therapeutics. This plastid is known to have been acquired by secondary endosymbiosis, but when this occurred and from which type of alga it was acquired remain uncertain. Based on the molecular phylogeny of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, we provide evidence that the apicomplexan plastid is homologous to plastids found in dinoflagellates-close relatives of apicomplexa that contain secondary plastids of red algal origin. Surprisingly, apicomplexan and dinoflagellate plastid-targeted GAPDH sequences were also found to be closely related to the plastid-targeted GAPDH genes of heterokonts and cryptomonads, two other groups that contain secondary plastids of red algal origin. These results address several outstanding issues: (1) apicomplexan and dinoflagellate plastids appear to be the result of a single endosymbiotic event which occurred relatively early in eukaryotic evolution, also giving rise to the plastids of heterokonts and perhaps cryptomonads; (2) apicomplexan plastids are derived from a red algal ancestor; and (3) the ancestral state of apicomplexan parasites was photosynthetic.

Symbiotic origin of a novel actin gene in the cryptophyte Pyrenomonas helgolandii

Cryptophytes are photosynthetic protists that have acquired their plastids through the secondary symbiotic uptake of a red alga. A remarkable feature of cryptophytes is that they maintain a reduced form of the red algal nucleus, the nucleomorph, between the second and third plastid membranes (periplastidial compartment; PC). The nucleomorph is thought to be a transition state in the evolution of secondary plastids, with this genome ultimately being lost when photosynthesis comes under full control of the "host" nucleus (e.g., as in heterokonts, haptophytes, and euglenophytes). Genes presently found in the nucleomorph seem to be restricted to those involved in its own maintenance and to that of the plastid; other genes were lost as the endosymbiont was progressively reduced to its present state. Surprisingly, we found that the cryptophyte Pyrenomonas helgolandii possesses a novel type of actin gene that originated from the nucleomorph genome of the symbiont. Our results demonstrate for the first time that secondary symbionts can contribute genes to the host lineage which are unrelated to plastid function. These genes are akin to the products of gene duplication or lateral transfer and provide a source of evolutionary novelty that can significantly increase the genetic diversity of the host lineage. We postulate that this may be a common phenomenon in algae containing secondary plastids that has yet to be fully appreciated due to a dearth of evolutionary studies of nuclear genes in these taxa.

Predictive value of wavelet decomposition of the signal-averaged electrocardiogram in idiopathic dilated cardiomyopathy

BACKGROUND

Wavelet decomposition of the signal-averaged electrocardiogram has been proposed as a method of detecting small and transient irregularities hidden within the QRS complex and of overcoming some of the limitations of time domain analysis of the signal-averaged electrocardiogram.

AIM

This study evaluated the potential utility of wavelet decomposition analysis in the risk stratification of patients with idiopathic dilated cardiomyopathy.

METHODS AND RESULTS

Both wavelet decomposition and time domain analysis were applied to the signal-averaged electrocardiogram recordings of 82 patients with idiopathic dilated cardiomyopathy (mean age 43 +/- 14 years, 60 men) and 72 normal controls (mean age 44 +/- 15 years, 48 men). Three conventional time domain indices and four wavelet decomposition analysis parameters (QRS length, maximum count, surface area, and relative length) were derived from each recording using a Del Mar CEWS system and an in-house software package, respectively. The results showed that (1) more patients with idiopathic dilated cardiomyopathy than without had late potentials, and that the filtered QRS duration was significantly longer in patients than in controls (P<0.001). Similarly, abnormal wavelet decomposition analysis was more common in patients and wavelet decomposition measurements were significantly different between patients and controls (P<0.01); (2) conventional time domain analysis did not distinguish between clinically stable patients and patients who developed progressive heart failure, or between patients with and without arrhythmic events; (3) wavelet decomposition analysis identified patients who went on to develop progressive heart failure but failed to distinguish patients with arrhythmic events from those without; (4) survival analyses of a mean follow-up of 23 months showed that patients with late potentials tended to develop progressive heart failure more frequently than others (P=0.06). Patients with an abnormal wavelet decomposition result more frequently developed progressive heart failure than those with a normal wavelet decomposition result (P=0.027); (5) in a univariate analysis (Cox model), wavelet decomposition measurements but not time domain indices significantly correlated with the development of progressive heart failure (P=0.01). Multivariate analysis showed that only left ventricular end-diastolic dimension and peak oxygen consumption during exercise remained significant predictors of progressive heart failure.

CONCLUSION

Wavelet decomposition analysis of the signal-averaged electrocardiogram is superior to conventional time domain analysis for identifying patients with idiopathic dilated cardiomyopathy at increased risk of clinical deterioration. Wavelet decomposition analysis, however, is unlikely to prospectively distinguish patients at a high risk of arrhythmic events in idiopathic dilated cardiomyopathy in its present form.

Evidence from beta-tubulin phylogeny that microsporidia evolved from within the fungi

Microsporidia are obligate intracellular parasites that were thought to be an ancient eukaryotic lineage based on molecular phylogenies using ribosomal RNA and translation elongation factors. However, this ancient origin of microsporidia has been contested recently, as several other molecular phylogenies suggest that microsporidia are closely related to fungi. Most of the protein trees that place microsporidia with fungi are not well sampled, however, and it is impossible to resolve whether microsporidia evolved from a fungus or from a protistan relative of fungi. We have sequenced beta-tubulins from 3 microsporidia, 4 chytrid fungi, and 12 zygomycete fungi, expanding the representation of beta-tubulin to include all four fungal divisions and a wide diversity of microsporidia. In phylogenetic trees including these new sequences, the overall topology of the fungal beta-tubulins generally matched the expected relationships among the four fungal divisions, although the zygomycetes were polyphyletic in some analyses. The microsporidia consistently fell within this fungal diversification, and not as a sister group to fungi. Overall, beta-tubulin phylogeny suggests that microsporidia evolved from a fungus sometime after the divergence of chytrids. We also found that chytrid alpha- and beta-tubulins are much less divergent than are tubulins from other fungi or microsporidia. In trees in which the only fungal representatives were the chytrids, microsporidia still branched with fungi (i.e., with chytrids), suggesting that the affiliation between microsporidian and fungal tubulins is not an artifact of long-branch attraction.

The secondary endosymbiont of the cryptomonad Guillardia theta contains alpha-, beta-, and gamma-tubulin genes

Cryptomonads have acquired photosynthesis through secondary endosymbiosis: they have engulfed and retained a photosynthetic eukaryote. The remnants of this autotrophic symbiont are severely reduced, but a small volume of cytoplasm surrounding the plastid persists, along with a residual nucleus (the nucleomorph) that encodes only a few hundred genes. We characterized tubulin genes from the cryptomonad Guillardia theta. Despite the apparent absence of microtubules in the endosymbiont, we recovered genes encoding alpha-, beta-, and gamma-tubulins from the nucleomorph genome of G. theta. The presence of tubulin genes in the nucleomorph indicates that some component of the cytoskeleton is still present in the cryptomonad symbiont despite the fact that very little cytoplasm remains, no mitosis is known in the nucleomorph, and microtubules have never been observed anywhere in the symbiont. Phylogenetic analyses with nucleomorph alpha- and beta-tubulins support the origin of the cryptomonad nucleomorph from a red alga. We also characterized alpha and beta-tubulins from the host nucleus of G. theta and compared these with tubulins we isolated from two flagellates, Goniomonas truncata and Cyanophora paradoxa, previously proposed to be related to the cryptomonad host. Phylogenetic analyses support a relationship between the cryptomonad host and Goniomonas but do not support any relationship between cryptomonads and Cyanophora.

Evolutionary relationship between translation initiation factor eIF-2gamma and selenocysteine-specific elongation factor SELB: change of function in translation factors

Eubacterial and eukaryotic translation initiation systems have very little in common, and therefore the evolutionary events that gave rise to these two disparate systems are difficult to ascertain. One common feature is the presence of initiation, elongation, and release factors belonging to a large GTPase superfamily. One of these initiation factors, the gamma subunit of initiation factor 2 (eIF-2gamma), is found only in eukaryotes and archaebacteria. We have sequenced eIF-2gamma gene fragments from representative diplomonads, parabasalia, and microsporidia and used these new sequences together with new archaebacterial homologues to examine the phylogenetic position of eIF-2gamma within the GTPase superfamily. The archaebacterial and eukaryotic eIF-2gamma proteins are found to be very closely related, and are in turn related to SELB, the selenocysteine-specific elongation factor from eubacteria. The overall topology of the GTPase tree further suggests that the eIF-2gamma/SELB group may represent an ancient subfamily of GTPases that diverged prior to the last common ancestor of extant life.

Sulfolobus islandicus plasmids pRN1 and pRN2 share distant but common evolutionary ancestry

The complete sequence of the plasmid pRN2 from the thermoacidophile Sulfolobus islandicus has been determined. The plasmid was found to be circular and 6959 bp in length. S. islandicus harbors another endogenous plasmid, pRN1, and comparison of pRN1 and pRN2 revealed that these two plasmids are essentially homologous, although very distantly related. pRN1 and pRN2 share several stretches of highly conserved noncoding DNA and three common open reading frames. Two of these reading frames are likely related to replication, one encoding a large protein with a helicase domain similar to viral helicases, and the other a copy number control protein, CopG.

Phylogenetic diversity of parabasalian symbionts from termites, including the phylogenetic position of Pseudotrypanosoma and Trichonympha

The phylogenetic diversity of parabasalian flagellates from termite hindguts has been examined by small subunit ribosomal RNA (rRNA) amplification and sequencing. Two species of particular interest, the giant trichomonad Pseudotrypanosoma giganteum and the hypermastigote Trichonympha magna, were isolated from the gut of Porotermes adamsoni by micropipetting, and the rRNA genes from these small populations amplified and sequenced. rRNA genes representing Hypermastigida and the Trichomonadida families Devescovinidae and Trichomonadidae, were also recovered by amplification from whole hindguts of three termites, P. adamsoni, Cryptotermes brevis, and Cryptotermes dudleyi. The parabasalian rRNA genes from C. brevis were found to comprise a unique and extremely heterogeneous lineage with no clear affinities to any known parabasalian rRNAs. In addition, one of the sequences isolated from P. adamsoni was found to be similar to another uncharacterised rRNA gene from Reticulitermes flavipes. The phylogeny of all known parabasalian small subunit rRNAs was examined with these new sequences. We find many taxonomic groups to be supported by rRNA, but not all. We have found the root of parabasalia to be very difficult to discern accurately, but have nevertheless identified several possible positions.

Nuclear-encoded proteins target to the plastid in Toxoplasma gondii and Plasmodium falciparum

A vestigial, nonphotosynthetic plastid has been identified recently in protozoan parasites of the phylum Apicomplexa. The apicomplexan plastid, or "apicoplast," is indispensable, but the complete sequence of both the Plasmodium falciparum and Toxoplasma gondii apicoplast genomes has offered no clue as to what essential metabolic function(s) this organelle might perform in parasites. To investigate possible functions of the apicoplast, we sought to identify nuclear-encoded genes whose products are targeted to the apicoplast in Plasmodium and Toxoplasma. We describe here nuclear genes encoding ribosomal proteins S9 and L28 and the fatty acid biosynthetic enzymes acyl carrier protein (ACP), beta-ketoacyl-ACP synthase III (FabH), and beta-hydroxyacyl-ACP dehydratase (FabZ). These genes show high similarity to plastid homologues, and immunolocalization of S9 and ACP verifies that the proteins accumulate in the plastid. All the putatively apicoplast-targeted proteins bear N-terminal presequences consistent with plastid targeting, and the ACP presequence is shown to be sufficient to target a recombinant green fluorescent protein reporter to the apicoplast in transgenic T. gondii. Localization of ACP, and very probably FabH and FabZ, in the apicoplast implicates fatty acid biosynthesis as a likely function of the apicoplast. Moreover, inhibition of P. falciparum growth by thiolactomycin, an inhibitor of FabH, indicates a vital role for apicoplast fatty acid biosynthesis. Because the fatty acid biosynthesis genes identified here are of a plastid/bacterial type, and distinct from those of the equivalent pathway in animals, fatty acid biosynthesis is potentially an excellent target for therapeutics directed against malaria, toxoplasmosis, and other apicomplexan-mediated diseases.

The phylogenetic position of alpha- and beta-tubulins from the Chlorarachnion host and Cercomonas (Cercozoa)

Alpha and beta-tubulin genes from Chlorarachnion and an alpha-tubulin gene from Cercomonas have been characterised. We found the Cercomonas and Chlorarachnion alpha tubulins to be closely related to one another, confirming the proposed relationship of these genera. In addition, the Chlorarachnion host and Cercomonas also appear to be more distantly related to Heterolobosea, Euglenozoa, chlorophytes, heterokonts, and alveolates. Chlorarachnion was also found to have two distinctly different types of both alpha- and beta-tubulin, one type being highly-divergent. Chlorarachnion contains a secondary endosymbiont of green algal origin, raising the possibility that one type of Chlorarachnion tubulins comes from the host and the other from the endosymbiont. Probing pulsed field-separated chromosomes showed that the highly-divergent genes are encoded by the host genome, and neither alpha- nor beta-tubulin cDNAs were found to include 5' extensions that might serve as targeting peptides. It appears that Chlorarachnion has distinct and divergent tubulin paralogues that are all derived from the host lineage. One Chlorarachnion beta-tubulin was also found to be a pseudogene, which is still expressed but aberrantly processed. Numerous unspliced introns and deletions resulting from mis-splicing are contained in the mRNAs from this gene.

Familial dilated cardiomyopathy: cardiac abnormalities are common in asymptomatic relatives and may represent early disease

OBJECTIVES

This study sought to determine whether early disease is identifiable in asymptomatic relatives of patients with dilated cardiomyopathy (DCM) by means of noninvasive cardiologic assessment.

BACKGROUND

DCM is diagnosed on the basis of advanced heart failure, where cardiac dilation and impaired contractility are recognized in the absence of a recognized etiology (World Health Organization criteria). However, initial clinical presentation may be with severe complications: thromboembolism, arrhythmia or sudden death. DCM has recently been recognized to be familial, with autosomal dominant inheritance in many cases. Familial disease is present in 9% to 20% of patients with DCM, and the ability to identify early disease in such people may improve patient management and aid in the understanding of pathogenesis.

METHOD

We prospectively assessed 408 asymptomatic relatives (mean [+/-SD] age 35 +/- 15 years, 193 men) of 110 consecutive patients with DCM by means of history and physical examination, two-dimensional echocardiography, 12-lead and signal-averaged electrocardiography and metabolic exercise testing. We hypothesized that signs of lesser cardiac dysfunction in such relatives might indicate early disease.

RESULTS

Twenty-nine percent of relatives had abnormal results on the echocardiogram. Twenty percent (n = 45) had left ventricular enlargement (LVE), defined as LV end-diastolic diameter (LVEDD) > or = 112% predicted; 6% (n = 13) had depressed fractional shortening (dFS), defined as FS < or = 25%; and 3% (n = 7) had frank DCM, defined as LV dilation, impaired contractile performance and LVEDD > or = 112% plus FS < or = 25%. Other abnormalities of cardiac function were identified in relatives with LVE or dFS: A greater number with LVE had an abnormal metabolic exercise test result than normal relatives (9% vs. 1%, p < 0.05). Relatives with LVE and abnormal maximal oxygen consumption (VO2max) (defined as VO2max < 80% predicted) had a lower absolute VO2max than normal relatives (30 +/- 8 vs. 43 +/- 9 ml/min per kg, p = 0.01). The QRS duration (at the 25-Hz filter) on the signal-averaged electrocardiogram was prolonged in relatives with LVE (103 +/- 13 ms) and dFS (102 +/- 12 ms) compared with that of normal relatives (97 +/- 12 ms, p < 0.05). Over a mean 39-month follow-up period, 12 relatives with LVE (27%) and none with dFS developed symptomatic DCM (p < 0.0001). One relative with LVE died suddenly, and another underwent heart transplantation.

CONCLUSIONS

Nearly one-third of asymptomatic relatives (29%) have echocardiographic abnormalities, and 27% of such relatives progress to development of overt DCM. Early identification of such people would permit appropriate intervention that might influence the serious complications and mortality of this disease.

Origins of microsporidia

Microsporidia are obligate intracellular parasites that infect a wide range of eukaryotes, causing severe diseases in immunocompromised humans and losses to apiaries, fisheries and silk farms. They have often been considered to be primitive eukaryotes; however, more recent evidence suggests they are more closely related to fungi.

Widespread and ancient distribution of a noncanonical genetic code in diplomonads

Recently, a group of diplomonads has been found to use a genetic code in which TAA and TAG encode glutamine rather than termination. To survey the distribution of this characteristic in diplomonads, we sought to identify TAA and TAG codons at positions where glutamine is expected in genes for alpha-tubulin, elongation factor-1 alpha, and the gamma subunit of eukaryotic translation initiation factor-2. These sequences show that the variant genetic code is utilized by almost all diplomonads, with the genus Giardia alone using the universal genetic code. Comparative phylogenetic analysis reveals that the switch to this genetic code took place very early in the evolution of diplomonads and was likely a single event. Termination signals and downstream untranslated regions were also cloned from three Hexamita genes. In all three of these genes, the predicted TGA termination codon was found at the expected position. Interestingly, the untranslated regions of these genes are high in AT. This is incongruent with the coding regions, which are comparatively GC-rich.

Usefulness of signal-averaged electrocardiography in evaluation of idiopathic-dilated cardiomyopathy in families

Family studies have confirmed that familial dilated cardiomyopathy is common and that a large proportion of relatives have mild left ventricular enlargement and therefore potentially early disease. Previous studies have shown that patients with idiopathic dilated cardiomyopathy have abnormalities of the signal-averaged electrocardiogram (ECG). We assessed the usefulness of analysis of the signal-averaged ECG in the evaluation of familial dilated cardiomyopathy. Signal-averaged electrocardiographic recordings were obtained from 58 patients with idiopathic dilated cardiomyopathy, from 161 of their relatives (35 of whom had left ventricular enlargement), and from 59 healthy subjects. Signal-averaged ECGs were analyzed using both time domain and spectral turbulence analysis techniques. The time domain and spectral turbulence analysis variables were markedly abnormal in patients with idiopathic dilated cardiomyopathy compared with relatives considered normal and healthy controls (p <0.05). Late potentials were more common in patients with idiopathic dilated cardiomyopathy (17%) and in relatives with left ventricular enlargement (20%) than in normal relatives (5%) or healthy controls (5%) (p = 0.003). Spectral turbulence analysis was abnormal in 24% of patients with idiopathic dilated cardiomyopathy, 14% of relatives with left ventricular enlargement, 6% of normal relatives, and 5% of healthy controls (p = 0.0006). The sensitivity, specificity, and positive predictive accuracy for identification of relatives with left ventricular enlargement were 20%, 95%, and 54% for time domain analysis and 14%, 94%, and 42% for spectral turbulence analysis. Similar positive predictive accuracy was achievable with spectral turbulence analysis and with time domain analysis. In conclusion, the signal-averaged ECG is frequently abnormal in patients with idiopathic dilated cardiomyopathy and relatives with left ventricular enlargement.

Evidence that eukaryotic triosephosphate isomerase is of alpha-proteobacterial origin

We have cloned and sequenced genes for triosephosphate isomerase (TPI) from the gamma-proteobacterium Francisella tularensis, the green non-sulfur bacterium Chloroflexus aurantiacus, and the alpha-proteobacterium Rhizobium etli and used these in phylogenetic analysis with TPI sequences from other members of the Bacteria, Archaea, and Eukarya. These analyses show that eukaryotic TPI genes are most closely related to the homologue from the alpha-proteobacterium and most distantly related to archaebacterial homologues. This relationship suggests that the TPI genes present in modern eukaryotic genomes were derived from an alpha-proteobacterial genome (possibly that of the protomitochondrial endosymbiont) after the divergence of Archaea and Eukarya. Among these eukaryotic genes are some from deeply branching, amitochondrial eukaryotes (namely Giardia), which further suggests that this event took place quite early in eukaryotic evolution.

Heart rate variability in idiopathic dilated cardiomyopathy: relation to disease severity and prognosis

OBJECTIVE

To assess the clinical importance of heart rate variability (HRV) in patients with idiopathic dilated cardiomyopathy (DCM).

PATIENTS AND METHODS

Time domain analysis of 24 hour HRV was performed in 64 patients with DCM, 19 of their relatives with left ventricular enlargement (possible early DCM), and 33 healthy control subjects.

RESULTS

Measures of HRV were reduced in patients with DCM compared with controls (P < 0.05). HRV parameters were similar in relatives and controls. Measures of HRV were lower in DCM patients in whom progressive heart failure developed (n = 28) than in those who remained clinically stable (n = 36) during a follow up of 24 (20) months (P = 0.0001). Reduced HRV was associated with NYHA functional class, left ventricular end diastolic dimension, reduced left ventricular ejection fraction, and peak exercise oxygen consumption (P < 0.05) in all patients. DCM patients with standard deviation of normal to normal RR intervals calculated over the 24 hour period (SDNN) < 50 ms had a significantly lower survival rate free of progressive heart failure than those with SDNN > 50 ms (P = 0.0002, at 12 months; P = 0.0001, during overall follow up). Stepwise multiple regression analysis showed that SDNN < 50 ms identified, independently of other clinical variables, patients who were at increased risk of developing progressive heart failure (P = 0.0004).

CONCLUSIONS

HRV is reduced in patients with DCM and related to disease severity. HRV is clinically useful as an early non-invasive marker of DCM deterioration.

Cardiac autoantibodies in dilated cardiomyopathy become undetectable with disease progression

OBJECTIVE

To determine the relation of cardiac autoantibody and disease status in a consecutive series of patients with dilated cardiomyopathy by prospective antibody testing at diagnosis and at follow up.

METHODS

Antibody status was assessed by indirect immunofluorescence in 110 patients with dilated cardiomyopathy (85 male, mean (SD) age 44 (13) years) at diagnosis and at follow up (mean (SD) 14 (12) months); in 57 of them cardiac specific anti-alpha myosin antibody titres were also measured by an enzyme-linked immunosorbent assay (ELISA). Patients underwent complete evaluation at diagnosis and clinical and non-invasive assessment at follow up, including exercise testing with maximal oxygen consumption measurements.

RESULTS

The frequency of cardiac specific antibodies by immunofluorescence was lower at follow up than at diagnosis (28 (25%) v 11 (10%), P = 0.002). Mean (SEM) anti-alpha myosin antibody titres at follow up were also lower than at diagnosis (0.24 (0.02) v 0.30 (0.02), P = 0.038); 24% of patients at diagnosis and 14% at follow up had an abnormal ELISA result. None of the patients who were negative by immunofluorescence or ELISA at diagnosis became positive at follow up. Presence of antibody at diagnosis was associated with milder symptoms and greater exercise capacity at follow up and persistence of antibody at follow up was associated with stable disease and milder symptoms at diagnosis.

CONCLUSIONS

Cardiac specific autoantibodies in dilated cardiomyopathy become undetectable with disease progression; this is a recognised feature of other autoimmune conditions, such as type 1 diabetes. Detection of these antibodies at diagnosis and at follow up may provide a non-invasive marker of early dilated cardiomyopathy.

Alpha-tubulin from early-diverging eukaryotic lineages and the evolution of the tubulin family

The tubulin gene family, which includes alpha-,beta-, and gamma-tubulin subfamilies, is composed of highly conserved proteins which are the principle structural and functional components of eukaryotic microtubules. We are interested in (1) establishing when in eukaryotic evolution the duplications leading to paralogous alpha, beta, and gamma subfamilies occurred and (2) the possible utility of tubulin sequences in reconstructing organismal phylogeny. To broaden the taxonomic representation of alpha-tubulins so that it roughly equals that of beta-tubulins, alpha-tubulin genes from three Microsporidia (Encephalitozoon hellem, Nosema locustae, and Spraguea lophii), two Parabasalia (Monocercomonas sp. and Trichomitus batrachorum), and one Heterolobosean (Acrasis rosea) were sequenced. With these new genes, phylogenetic trees of alpha- and beta-tubulins were constructed and compared. Trees were congruent with each other, but incongruent with other molecular phylogenies. The agreement between alpha- and beta-tubulin trees could arise by the co-adaptation of one molecule to variants of the other as a result of their intimate steric association in microtubules. Thus, these trees may not be providing independent support for the phylogenetic results. However, one of these unexpected results, that microsporidia cluster with fungi, is supported by other circumstantial evidence, and may therefore reflect a real relationship despite the basal position usually assigned to microsporidia. Relationships between the three tubulins were also examined by constructing trees of all three types. These trees were found to be of limited value for determining the position of the root within each subfamily because of the great interfamily distances, but they do confirm the classification of all known genes into three monophyletic subfamilies. Divergent genes from Caenorhabditis elegans and Saccharomyces cerevisiae that have been proposed to represent the novel classes delta- and epsilon-tubulin were found to be specifically related to gamma-tubulins from animals and fungi respectively, and therefore are best seen as rapidly evolving orthologues of gamma-tubulin.

Linked genes for calmodulin and E2 ubiquitin-conjugating enzyme in Trichomonas vaginalis

In searching the genomes of early-diverging protists to study whether the possession of calmodulin is ancestral to all eukaryotes, the gene for calmodulin was identified in Trichomonas vaginalis. This flagellate is a member of the Parabasalia, one of the earliest lineages of recognized eukaryotes to have diverged. This sequence was used to isolate a homologous 1.250-kb fragment from the T. vaginalis genome by inverse polymerase chain reaction. This fragment was also completely sequenced and shown to contain the 3' end of the single-copy calmodulin gene and the 3' end of a gene encoding a protein with high similarity to E2 ubiquitin-conjugating enzymes, a family which has previously only been identified in animals, plants, and fungi. Phylogenetic analysis of 50 members of the E2 family distinguishes at least nine separate subfamilies one of which includes the T. vaginalis E2-homologue and an uncharacterized gene from yeast chromosome XII.

Comparison of time domain and spectral turbulence analysis of the signal-averaged electrocardiogram for the prediction of prognosis in idiopathic dilated cardiomyopathy

BACKGROUND

Despite significant advances in the treatment of heart failure, the prognosis of patients with idiopathic dilated cardiomyopathy remains poor. Although several of prognostic variables have been shown to be useful in risk stratification of patients with idiopathic dilated cardiomyopathy, their predictive accuracy is low and clinical usefulness uncertain.

HYPOTHESIS

This study was undertaken to assess the signal-averaged electrocardiogram (SAECG) in patients with idiopathic dilated cardiomyopathy and to compare the ability of time domain and spectral turbulence analytic techniques to predict clinical outcome.

METHODS

SAECG analysis was performed in 80 patients with idiopathic dilated cardiomyopathy. Nineteen patients had left bundle-branch block and eight were taking low-dose amiodarone for life-threatening arrhythmias. Conventional time domain and spectral turbulence analyses of the SAECG were performed using Del Mar 183 software.

RESULTS

During a follow-up of 27 +/- 19 months, 24 patients developed progressive heart failure, while the others remained clinically stable. Late potentials were detected in 28% of patients and were equally frequent in patients with and without progressive heart failure (38 vs. 23%, p = 0.20). Spectral turbulence analysis was abnormal in 34% of patients, and patients with abnormal results developed progressive heart failure more frequently than those with normal results (50 vs. 17%, p = 0.01). All spectral turbulence analysis parameters were significantly different in patients with progressive heart failure compared with those who remained clinically stable (p < or = 0.01). Furthermore, progressive heart failure-free survival at 2 years was significantly lower in patients with abnormal compared with normal results (63 vs. 87%; p < 0.05), but was similar in patients with and without late potentials (72 vs. 83%; p = 0.30). The relative risk for developing progressive heart failure using spectral turbulence analysis was 3.4 (95% confidence interval 1.2-9.7) and 2.8 (95% confidence interval 1.1-8.7) using time domain analysis. The sensitivity, specificity, and the positive and negative predictive accuracy for identifying patients who developed progressive heart failure were 50, 83, 50, and 83%, respectively, (p = 0.01) for spectral turbulence analysis, and 36, 85, 45 and 80%, respectively, (p = 0.09) for time domain analysis.

CONCLUSION

Abnormalities in the SAECG of patients with idiopathic dilated cardiomyopathy are common and appear to provide a noninvasive marker for development of progressive heart failure.

A non-canonical genetic code in an early diverging eukaryotic lineage

The nearly invariant nature of the 'Universal Genetic Code' attests to its early establishment in evolution and to the difficulty of altering it now, since so many molecules are required for, and depend upon, faithful translation. Nevertheless, variations on the universal code are known in a handful of genomes. We have found one such variant in diplomonads, an early-diverging eukaryotic lineage. Genes for alpha-tubulin, beta-tubulin and elongation factor 1 alpha (EF-1alpha) from two unclassified strains of Hexamitidae were found to contain TAA and TAG (TAR) triplets at positions suggesting a variant code in which TAR codes for glutamine. We found confirmation of this hypothesis by identifying genes encoding glutamine-tRNAs with CUA and UUA anticodons. The alpha-tubulin and EF-1alpha genes from two other diplomonads, Spironucleus muris and Hexamita inflata, were also sequenced and shown to contain no such non-canonical codons. However, tRNA genes with the anticodons UUA and CUA were found in H.inflata, suggesting that this diplomonad also uses these codons, albeit infrequently. The high GC content of these genomes and the presence of two isoaccepting tRNAs compound the difficulty of understanding how this variant code arose by strictly neutral means.

Decreased heart rate variability in patients with congestive heart failure and chronotropic incompetence

Heart rate variability was studied in 41 patients (aged 48 +/- 12 years) with congestive heart failure secondary to idiopathic dilated cardiomyopathy. All patients underwent a treadmill exercise test and 24-hour Holter ECG monitoring. Chronotropic incompetence was defined as the failure to achieve > or = 80% of the predicted maximal heart rate response given by 220--age (years) at peak exercise. Spectral heart rate variability was analyzed from 24-hour Holter ECGs and was expressed as total (0.01-1.00 Hz), low (0.04-0.15 Hz), and high (0.15-0.40 Hz) frequency components. The standard deviation of all normal RR intervals (SDNN) was also computed. Chronotropic incompetence was observed in ten patients. Peak oxygen consumption was significantly lower in patients with chronotropic incompetence compared with those without chronotropic incompetence. The total (5.11 +/- 1.26 ln [ms2] vs 6.41 +/- 0.92 ln [ms2]; P = 0.009) and low (3.38 +/- 1.65 ln [ms2] vs 5.45 +/- 1.34 ln [ms2]; P = 0.003), but not the high (3.42 +/- 1.04 ln [ms2] vs 4.00 +/- 1.12 ln [ms2]; P = 0.249) frequency components of heart rate variability were significantly lower in patients with chronotropic incompetence, although there was no significant difference in mean heart rate (88 +/- 20 beats/min vs 86 +/- 15 beats/min; P = 0.831) or left ventricular ejection fraction (22% +/- 10% vs 24% +/- 10%; P = 0.619). SDNN was also significantly lower in patients with chronotropic incompetence compared with those without chronotropic incompetence (64 +/- 34 ms vs 102 +/- 37 ms; P = 0.030).

CONCLUSIONS

The observation that heart rate variability is significantly decreased in patients with congestive heart failure who have chronotropic incompetence suggests that chronotropic incompetence may relate to an abnormal autonomic influence on the heart in these patients.

Expression of inducible nitric oxide synthase in human heart failure

BACKGROUND

There is increasing evidence that alterations in nitric oxide synthesis are of pathophysiological importance in heart failure. A number of studies have shown altered nitric oxide production by the endothelial constitutive isoform of nitric oxide synthase (NOS), but there is very little information on the role of the inducible isoform.

METHODS AND RESULTS

We analyzed inducible NOS (iNOS) expression in ventricular myocardium taken from 11 control subjects (who had died suddenly from noncardiac causes), from 10 donor hearts before implantation, and from 51 patients with heart failure (24 with dilated cardiomyopathy [DCM], 17 with ischemic heart disease [IHD], and 10 with valvular heart disease [VHD]). Reverse transcription-polymerase chain reaction was used to confirm the presence of intact mRNA and to detect expression of iNOS and atrial natriuretic peptide (ANP). ANP was used as a molecular phenotypic marker of ventricular failure. iNOS was expressed in 36 of 51 biopsies (71%) from patients with heart failure and in none of the control patients (P<.0001). iNOS expression could also be detected in 50% of the donor hearts. All samples that expressed iNOS also expressed ANP. iNOS gene expression occurred in 67% of patients with DCM, 59% of patients with IHD, and 100% of patients with VHD. To determine whether iNOS protein was expressed in failing ventricles, immunohistochemistry was performed on three donor hearts and nine failing hearts with iNOS mRNA expression. Staining for iNOS was almost undetectable in the donor myocardium and in control sections, but all failing hearts showed diffuse cytoplasmic staining in cardiac myocytes. Expression of iNOS could be observed in all four chambers. Western blot analysis with the same primary antibody showed a specific positive band for iNOS protein in the heart failure specimens; minimal iNOS protein expression was seen in donor heart samples.

CONCLUSIONS

iNOS expression occurs in failing human cardiac myocytes and may be involved in the pathophysiology of DCM, IHD, and VHD.

Complete nucleotide sequence of the Sulfolobus islandicus multicopy plasmid pRN1

The complete sequence of the 5350-bp plasmid pRN1 from the crenarchaeote Sulfolobus islandicus has been determined. This plasmid is the first to be sequenced from this group of thermoacidophilic archaebacteria (Archaea) and its high copy number and wide host range make it a good candidate for a cloning vector. pRN1 contains several open reading frames, including one that spans over half the plasmid and has significant similarity to the helicase domain of viral primase proteins. Directly upstream of this putative primase is a homologue of Cop, a family of small proteins from promiscuous eubacterial plasmids which control copy number by repressing the expression of the replication initiation protein. In eubacterial plasmids cop is found upstream of the replication initiator protein. The location of a cop homologue upstream of a primase-like gene in pRN1 suggests that it controls DNA replication in a manner similar to these eubacterial plasmids, but does so using a mixture of components from plasmids and viruses.

Abnormal cytokine profiles in patients with idiopathic dilated cardiomyopathy and their asymptomatic relatives

OBJECTIVES

Immunological abnormalities in idiopathic dilated cardiomyopathy (DCM) include an increase in soluble interleukin (IL)-2 receptor, disease specific cardiac autoantibodies, an HLA-DR4 association, and familial aggregation of disease; however, cytokine profiles have not been defined. Serum concentrations of IL-2, IL-4, IL-10, and IL-12 were measured in patients with DCM (WHO criteria), relatives with asymptomatic left ventricular enlargement (LVE), patients with ischaemic heart failure (IHD), and healthy controls.

DESIGN

Serum from 20 individuals from each of the four groups was assayed for cytokine concentrations by a commercial enzyme linked immunosorbent assay.

RESULTS

IL-2 concentrations were abnormally increased in DCM patients and relatives with LVE. Concentrations of IL-10 were increased in DCM patients. Concentrations of IL-4 and IL-12 were not increased in any of the groups.

CONCLUSION

These abnormalities may reflect defective/inappropriate T cell function in patients with DCM and in their relatives with LVE.

QT dispersion and RR variations on 12-lead ECGs in patients with congestive heart failure secondary to idiopathic dilated cardiomyopathy

Increased QT dispersion, which has been proposed as a marker of ventricular repolarization inhomogeneity, may predispose to ventricular arrhythmias. Data on QT dispersion in patients with congestive heart failure are scarce. In this study, conventional 12-lead ECGs were recorded in 135 consecutive patients with congestive heart failure secondary to idiopathic dilated cardiomyopathy. Seventy-five patients were excluded from QT interval assessments due to one or more of the following reasons: (1) low amplitude of the T wave (n = 3), (2) atrial fibrillation (n = 26) and (3) bundle branch block (n = 46). QT dispersion was calculated as (1) QT-range: the difference between the maximum and minimum QT intervals on any of the 12 leads and (2) QT-SD: the standard deviation of the QT interval in all the 12 leads. RR intervals were measured in leads II, aVL, V2 and V5. QT-SD (20.85 +/- 5.00 ms) was significantly (r = 0.8997, P < 0.001) related to QT-range (65.65 +/- 15.77 ms), but not to the QT interval. Neither QT-range nor QT-SD was significantly related to age, left ventricular dimensions, left ventricular end diastolic pressure, left ventricular ejection fraction or left ventricular wall thickness. There was no significant difference in QT dispersion between survivors and those who died (n = 8) or were transplanted (n = 9) during 34 +/- 23 month follow-up. No significant difference in QT dispersion was observed between patients with and without ventricular tachycardia (> or = three consecutive beats) detected on 24-h Holter ECGs. RR interval variation was significantly lower in patients who died compared with survivors (standard deviation: 10.37 +/- 3.61 vs 36.02 +/- 35.03 ms, P < 0.001; coefficient of variance: 1.87 +/- 0.7% vs 4.50 +/- 4.9%, P = 0.001). This was also true in patients with bundle branch block. These observations suggest that QT dispersion in idiopathic dilated cardiomyopathy is not significantly related to either QT interval or cardiac size and function and does not predict death. The application of QT dispersion assessment is limited by the commonly encountered atrial fibrillation and bundle branch block in this patient population. However, reduced RR variation on standard 12-lead ECGs has important prognostic implications in these patients.

Organ-specific cardiac autoantibodies in dilated cardiomyopathy--an update

Autoimmune disease is characterized by the presence of organ- and disease-specific autoantibodies in patients and first degree relatives; antibody detection may precede disease onset by several years. We investigated potential involvement of organ-specific autoimmunity in dilated cardiomyopathy (DCM). Using indirect immunofluorescence and absorption studies, organ- and disease-specific IgG cardiac antibodies were found in one-third of DCM patients. Antibody status at diagnosis was associated with better exercise capacity; at 1-year follow-up two-thirds of antibody-positive patients became negative. These findings suggest that antibodies are early markers; their absence in the majority of patients at diagnosis may relate to long-standing pre-clinical DCM. Antibody screening was performed in asymptomatic DCM relatives, 177 from 33 families with > 1 affected individual (familial DCM) and 165 from 31 pedigrees with non-familial DCM. Antibodies were detected in 37 (58%) pedigrees and were more common among relatives than in normals (20% vs 3.5%, P = 0.0001). Antibody-positive relatives were younger, had larger left ventricular end-systolic dimension and reduced % fractional shortening compared to antibody-negative relatives. These findings provide evidence for autoimmunity in a subset (58%) including both familial and non-familial DCM; cardiac-specific antibodies may identify relatives at risk of developing DCM.

Autoimmunity to alpha myosin in a subset of patients with idiopathic dilated cardiomyopathy

OBJECTIVE

To use an enzyme linked immunoassay (ELISA) technique to assess frequency and disease specificity of anti-alpha-myosin antibodies in patients with dilated cardiomyopathy and their relatives.

METHODS

Evaluation was performed on sera (dilution 1/320) from 123 consecutive patients with dilated cardiomyopathy (WHO criteria) (age 42 (SD 14) years), 252 of their relatives (35 (17) years), 203 healthy controls (45 (16) years), and 92 patients with ischaemic heart disease (63 (11) years).

RESULTS

Abnormal antibody levels were commoner in patients with dilated cardiomyopathy (25, 20%) than in ischaemic heart disease (4, 4%), or normal controls (4, 2%, P = 0.001). Forty one (16%) of the relatives had abnormal results compared to the controls (4, 2%, P < 0.001) and antibodies were detected in 20 (38%) of pedigrees. Relatives from non-familial kindreds had higher antibody levels than those with familial disease (P << 0.001), and higher antibody levels were identified in 53 relatives of probands who had abnormal results compared to 116 relatives for whom the proband had a normal result (0.37 (SEM 0.02) v 0.22 (0.01); P < 0.001).

CONCLUSIONS

The finding of anti-alpha-myosin antibodies in 20% of patients with dilated cardiomyopathy, in 16% of their asymptomatic relatives, and in 38% of families (particularly those with non-familial disease and where proband also had an abnormal result) provides additional evidence for autoimmunity against alpha myosin in a subset of patients.

Prognosis of idiopathic dilated cardiomyopathy

Previous reports in referral populations have emphasized the poor prognosis of dilated cardiomyopathy. This study evaluated mortality and morbidity in patients presenting at a referral center between 1989 and 1993. One hundred seventy-two consecutive patients were studied. At presentation, 82 were in New York Heart Association functional class III/IV. Mean (+/- SD) left ventricular end-diastolic dimension was 69 +/- 11 mm, ejection fraction was 25 +/- 10%, VO2 max was 21 +/- 9 mL/min/kg, and sodium was 136 +/- 9 mM. Treatments included vasodilators (n = 157, 92%), anticoagulation (n = 50, 29%), amiodarone (n = 52, 30%), and cardiac defibrillator (n = 5, 3%). During the follow-up period (mean, 26 +/- 29 months), 16 patients died and 60 developed progressive heart failure; 46 (27%) required cardiac transplantation. The majority of the patients (102, 59%) were stable or improved. Established prognostic determinants (left ventricular end-diastolic dimension, ejection fraction, sodium, and arrhythmia) were of low predictive value for the development of progressive heart failure or sudden death. The 1- and 2-year probabilities of death or transplantation was 16 and 21%, respectively (death only 6 and 7%, respectively). These observations are subject to referral bias, but suggest that the majority of patients can remain stable. Any improvement in survival compared to earlier experience can be due to earlier diagnosis, availability of transplantation, and new heart failure management strategies.

Concerted evolution in protists: recent homogenization of a polyubiquitin gene in Trichomonas vaginalis

Ubiquitin is a 76-amino-acid protein with a remarkably high degree of conservation between all known sequences. Ubiquitin genes are almost always multicopy in eukaryotes, and often are found as polyubiquitin genes--fused tandem repeats which are coexpressed. Seventeen ubiquitin sequences from the amitochondrial protist Trichomonas vaginalis have been examined here, including an 11-repeat fragment of a polyubiquitin gene. These sequences reveal a number of interesting features that are not seen in other eukaryotes. The predicted amino acid sequences lack several universally conserved residues, and individual units do not always encode identical peptides as is usually the case. On the nucleotide level, these repeats are in general highly variable, but one region in the polyubiquitin is extremely homogeneous, with seven repeats absolutely identical. Such extended stretches of homogeneity have never been observed in ubiquitin genes and since substitutions are common in other coding units, it is likely that these repeats are the product of a very recent homogenization or amplification.