Metabolic trade-offs in childhood: Exploring the relationship between language development and body growth

During human childhood, brain development and body growth compete for limited metabolic resources, resulting in a trade-off where energy allocated to brain development can decrease as body growth accelerates. This preregistered study explores the relationship between language skills, serving as a proxy for brain development, and body mass index at three distinct developmental stages, representing different phases of body growth. Longitudinal data from 2002 children in the EDEN mother-child cohort were analyzed using structural equation modeling. Our findings reveal a compelling pattern of associations: girls with a delayed adiposity rebound, signaling slower growth rate, demonstrated better language proficiency at ages 5-6. Importantly, this correlation appears to be specific to language skills and does not extend to nonverbal cognitive abilities. Exploratory analyses show that early environmental factors contributing to enhanced cognitive development, such as higher parental socio-economic status and increased cognitive stimulation, are positively associated with both language skills and the timing of adiposity rebound in girls. Overall, our findings lend support to the existence of an energy allocation trade-off mechanism that appears to prioritize language function over body growth investment in girls.

Impact of Rhamnolipids (RLs), Natural Defense Elicitors, on Shoot and Root Proteomes of Brassica napus by a Tandem Mass Tags (TMTs) Labeling Approach

The rapeseed crop is susceptible to many pathogens such as parasitic plants or fungi attacking aerial or root parts. Conventional plant protection products, used intensively in agriculture, have a negative impact on the environment as well as on human health. There is therefore a growing demand for the development of more planet-friendly alternative protection methods such as biocontrol compounds. Natural rhamnolipids (RLs) can be used as elicitors of plant defense mechanisms. These glycolipids, from bacteria secretome, are biodegradable, non-toxic and are known for their stimulating and protective effects, in particular on rapeseed against filamentous fungi. Characterizing the organ responsiveness to defense-stimulating compounds such as RLs is missing. This analysis is crucial in the frame of optimizing the effectiveness of RLs against various diseases. A Tandem Mass Tags (TMT) labeling of the proteins extracted from the shoots and roots of rapeseed has been performed and showed a differential pattern of protein abundance between them. Quantitative proteomic analysis highlighted the differential accumulation of parietal and cytoplasmic defense or stress proteins in response to RL treatments with a clear effect of the type of application (foliar spraying or root absorption). These results must be considered for further use of RLs to fight specific rapeseed pathogens.

The impact of alphabetic literacy on the perception of speech sounds

The aim of the present study was to evaluate the impact of literacy on phoneme perception. It built on previous research by using more controlled stimuli than in former studies and by independently examining the impacts of literacy and age on phoneme perception. Participants were adult and children beginning readers, and skilled adult readers. They were presented with identification and discrimination tasks, using a voicing continuum. In addition to examining their categorical perception of speech sounds and the precision of phonemic categories, participants' literacy level was carefully evaluated. The results confirmed that neither age nor literacy modulated categorical perception. However, level of literacy did have a significant impact on the precision of phonemic categories, which was independent from the influence of age.

PME58 plays a role in pectin distribution during seed coat mucilage extrusion through homogalacturonan modification

Pectins are major components of plant primary cell walls. They include homogalacturonans (HGs), which are the most abundant pectin and can be the target of apoplastic enzymes like pectin methylesterases (PMEs) that control their methylesterification level. Several PMEs are expressed in the seed coat of Arabidopsis thaliana, particularly in mucilage secretory cells (MSCs). On the basis of public transcriptomic data, seven PME genes were selected and checked for their seed-specific expression by quantitative reverse transcription PCR. Of these, PME58 presented the highest level of expression and was specifically expressed in MSCs at the early stages of seed development. pme58 mutants presented two discrete phenotypes: (i) their adherent mucilage was less stained by ruthenium red when compared to wild-type seeds, but only in the presence of EDTA, a Ca(2+)chelator; and (ii) the MSC surface area was decreased. These phenotypes are the consequence of an increase in the degree of HG methylesterification connected to a decrease in PME activity. Analysis of the sugar composition of soluble and adherent mucilage showed that, in the presence of EDTA, sugars of adherent mucilage were more readily extracted in pme58 mutants. Immunolabelling with LM19, an antibody that preferentially recognizes unesterified HGs, also showed that molecular interactions with HGs were modified in the adherent mucilage of pme58 mutants, suggesting a role of PME58 in mucilage structure and organization. In conclusion, PME58 is the first PME identified to play a direct role in seed mucilage structure.

PECTIN METHYLESTERASE48 is involved in Arabidopsis pollen grain germination

Germination of pollen grains is a crucial step in plant reproduction. However, the molecular mechanisms involved remain unclear. We investigated the role of PECTIN METHYLESTERASE48 (PME48), an enzyme implicated in the remodeling of pectins in Arabidopsis (Arabidopsis thaliana) pollen. A combination of functional genomics, gene expression, in vivo and in vitro pollen germination, immunolabeling, and biochemical analyses was used on wild-type and Atpme48 mutant plants. We showed that AtPME48 is specifically expressed in the male gametophyte and is the second most expressed PME in dry and imbibed pollen grains. Pollen grains from homozygous mutant lines displayed a significant delay in imbibition and germination in vitro and in vivo. Moreover, numerous pollen grains showed two tips emerging instead of one in the wild type. Immunolabeling and Fourier transform infrared analyses showed that the degree of methylesterification of the homogalacturonan was higher in pme48-/- pollen grains. In contrast, the PME activity was lower in pme48-/-, partly due to a reduction of PME48 activity revealed by zymogram. Interestingly, the wild-type phenotype was restored in pme48-/- with the optimum germination medium supplemented with 2.5 mm calcium chloride, suggesting that in the wild-type pollen, the weakly methylesterified homogalacturonan is a source of Ca(2+) necessary for pollen germination. Although pollen-specific PMEs are traditionally associated with pollen tube elongation, this study provides strong evidence that PME48 impacts the mechanical properties of the intine wall during maturation of the pollen grain, which, in turn, influences pollen grain germination.

The cell wall pectic polymer rhamnogalacturonan-II is required for proper pollen tube elongation: implications of a putative sialyltransferase-like protein

BACKGROUND AND AIMS

Rhamnogalacturonan-II (RG-II) is one of the pectin motifs found in the cell wall of all land plants. It contains sugars such as 2-keto-3-deoxy-d-lyxo-heptulosaric acid (Dha) and 2-keto-3-deoxy-d-manno-octulosonic acid (Kdo), and within the wall RG-II is mostly found as a dimer via a borate diester cross-link. To date, little is known regarding the biosynthesis of this motif. Here, after a brief review of our current knowledge on RG-II structure, biosynthesis and function in plants, this study explores the implications of the presence of a Golgi-localized sialyltransferase-like 2 (SIA2) protein that is possibly involved in the transfer of Dha or Kdo in the RG-II of Arabidopsis thaliana pollen tubes, a fast-growing cell type used as a model for the study of cell elongation.

METHODS

Two heterozygous mutant lines of arabidopsis (sia2-1+/- and qrt1 × sia2-2+/-) were investigated. sia2-2+/- was in a quartet1 background and the inserted T-DNA contained the reporter gene β-glucuronidase (GUS) under the pollen-specific promoter LAT52. Pollen germination and pollen tube phenotype and growth were analysed both in vitro and in vivo by microscopy.

KEY RESULTS

Self-pollination of heterozygous lines produced no homozygous plants in the progeny, which may suggest that the mutation could be lethal. Heterozygous mutants displayed a much lower germination rate overall and exhibited a substantial delay in germination (20 h of delay to reach 30 % of pollen grain germination compared with the wild type). In both lines, mutant pollen grains that were able to produce a tube had tubes that were either bursting, abnormal (swollen or dichotomous branching tip) or much shorter compared with wild-type pollen tubes. In vivo, mutant pollen tubes were restricted to the style, whereas the wild-type pollen tubes were detected at the base of the ovary.

CONCLUSIONS

This study highlights that the mutation in arabidopsis SIA2 encoding a sialyltransferase-like protein that may transfer Dha or Kdo on the RG-II motif has a dramatic effect on the stability of the pollen tube cell wall.

Arabidopsis PECTIN METHYLESTERASE17 is co-expressed with and processed by SBT3.5, a subtilisin-like serine protease

BACKGROUND AND AIMS

In Arabidopsis thaliana, the degree of methylesterification (DM) of homogalacturonans (HGs), the main pectic constituent of the cell wall, can be modified by pectin methylesterases (PMEs). In all organisms, two types of protein structure have been reported for PMEs: group 1 and group 2. In group 2 PMEs, the active part (PME domain, Pfam01095) is preceded by an N-terminal extension (PRO part), which shows similarities to PME inhibitors (PMEI domain, Pfam04043). This PRO part mediates retention of unprocessed group 2 PMEs in the Golgi apparatus, thus regulating PME activity through a post-translational mechanism. This study investigated the roles of a subtilisin-type serine protease (SBT) in the processing of a PME isoform.

METHODS

Using a combination of functional genomics, biochemistry and proteomic approaches, the role of a specific SBT in the processing of a group 2 PME was assessed together with its consequences for plant development.

KEY RESULTS

A group 2 PME, AtPME17 (At2g45220), was identified, which was highly co-expressed, both spatially and temporally, with AtSBT3.5 (At1g32940), a subtilisin-type serine protease (subtilase, SBT), during root development. PME activity was modified in roots of knockout mutants for both proteins with consequent effects on root growth. This suggested a role for SBT3.5 in the processing of PME17 in planta. Using transient expression in Nicotiana benthamiana, it was indeed shown that SBT3.5 can process PME17 at a specific single processing motif, releasing a mature isoform in the apoplasm.

CONCLUSIONS

By revealing the potential role of SBT3.5 in the processing of PME17, this study brings new evidence of the complexity of the regulation of PMEs in plants, and highlights the need for identifying specific PME-SBT pairs.

Further insights into the isoenzyme composition and activity of glutamate dehydrogenase in Arabidopsis thaliana

Following the discovery that in Arabidopsis, a third isoenzyme of NADH-dependent glutamate dehydrogenase (GDH) is expressed in the mitochondria of the root companion cells, we have re-examined the GDH isoenzyme composition. By analyzing the NADH-GDH isoenzyme composition of single, double and triple mutants deficient in the expression of the three genes encoding the enzyme, we have found that the α, β and γ polypeptides that comprise the enzyme can be assembled into a complex combination of heterohexamers in roots. Moreover, we observed that when one or two of the three root isoenzymes were missing from the mutants, the remaining isoenzymes compensated for this deficiency. The significance of such complexity is discussed in relation to the metabolic and signaling function of the NADH-GDH enzyme. Although it has been shown that a fourth gene encoding a NADPH-dependent enzyme is present in Arabidopsis, we were not able to detect corresponding enzyme activity, even in the triple mutant totally lacking NADH-GDH activity.

Perception of speech features by French-speaking children with cochlear implants

PURPOSE

The present study investigates the perception of phonological features in French-speaking children with cochlear implants (CIs) compared with normal-hearing (NH) children matched for listening age.

METHOD

Scores for discrimination and identification of minimal pairs for all features defining consonants (e.g., place, voicing, manner, nasality) and vowels (e.g., frontness, nasality, aperture) were measured in each listener.

RESULTS

The results indicated no differences in "categorical perception," specified as a similar difference between discrimination and identification between CI children and controls. However, CI children demonstrated a lower level of "categorical precision," that is, lesser accuracy in both feature identification and discrimination, than NH children, with the magnitude of the deficit depending on the feature.

CONCLUSIONS

If sensitive periods of language development extend well beyond the moment of implantation, the consequences of hearing deprivation for the acquisition of categorical perception should be fairly important in comparison to categorical precision because categorical precision develops more slowly than categorical perception in NH children. These results do not support the idea that the sensitive period for development of categorical perception is restricted to the first 1-2 years of life. The sensitive period may be significantly longer. Differences in precision may reflect the acoustic limitations of the cochlear implant, such as coding for temporal fine structure and frequency resolution.

The ZmASR1 protein influences branched-chain amino acid biosynthesis and maintains kernel yield in maize under water-limited conditions

Abscisic acid-, stress-, and ripening-induced (ASR) proteins were first described about 15 years ago as accumulating to high levels during plant developmental processes and in response to diverse stresses. Currently, the effects of ASRs on water deficit tolerance and the ways in which their physiological and biochemical functions lead to this stress tolerance remain poorly understood. Here, we characterized the ASR gene family from maize (Zea mays), which contains nine paralogous genes, and showed that maize ASR1 (ZmASR1) was encoded by one of the most highly expressed paralogs. Ectopic expression of ZmASR1 had a large overall impact on maize yield that was maintained under water-limited stress conditions in the field. Comparative transcriptomic and proteomic analyses of wild-type and ZmASR1-overexpressing leaves led to the identification of three transcripts and 16 proteins up- or down-regulated by ZmASR1. The majority of them were involved in primary and/or cellular metabolic processes, including branched-chain amino acid (BCAA) biosynthesis. Metabolomic and transcript analyses further indicated that ZmASR1-overexpressing plants showed a decrease in BCAA compounds and changes in BCAA-related gene expression in comparison with wild-type plants. Interestingly, within-group correlation matrix analysis revealed a close link between 13 decreased metabolites in ZmASR1-overexpressing leaves, including two BCAAs. Among these 13 metabolites, six were previously shown to be negatively correlated to biomass, suggesting that ZmASR1-dependent regulation of these 13 metabolites might contribute to regulate leaf growth, resulting in improvement in kernel yield.

Reading and reading-related skills in children using cochlear implants: prospects for the influence of cued speech

We assessed the reading and reading-related skills (phonemic awareness and phonological short-term memory) of deaf children fitted with cochlear implants (CI), either exposed to cued speech early (before 2 years old) (CS+) or never (CS-). Their performance was compared to that of 2 hearing control groups, 1 matched for reading level (RL), and 1 matched for chronological age (CA). Phonemic awareness and phonological short-term memory were assessed respectively through a phonemic similarity judgment task and through a word span task measuring phonological similarity effects. To assess the use of sublexical and lexical reading procedures, children read pseudowords and irregular words aloud. Results showed that cued speech improved performance on both the phonemic awareness and the reading tasks but not on the phonological short-term memory task. In phonemic awareness and reading, CS+ children obtained accuracy and rapidity scores similar to CA controls, whereas CS- children obtained lower scores than hearing controls. Nevertheless, in phonological short-term memory task, the phonological similarity effect of both CI groups was similar. Overall, these results support the use of cued speech to improve phonemic awareness and reading skills in CI children.

A gene encoding a protein with a proline-rich domain (MtPPRD1), revealed by suppressive subtractive hybridization (SSH), is specifically expressed in the Medicago truncatula embryo axis during germination

A gene MtPPRD1, encoding a protein of 132 amino acids containing a proline-rich domain (PRD), has been revealed by suppressive subtractive hybridization (SSH) with two mRNA populations of embryo axes harvested immediately before and after radicle emergence. Although at the protein level MtPPRD1 showed low homology with plant lipid transfer proteins (LTPs), it did exhibit the eight cysteine residues conserved in all plant LTPs, a characteristic signature that allows the formation of a hydrophobic cavity adapted for loading hydrophobic molecules. Expression studies of MtPPRD1 have been carried out by quantitative real time RT-PCR throughout germination and post-germination processes in control seeds and seeds in which germination was delayed by abscisic acid (ABA) or the glutamine synthetase inhibitor methionine sulphoximine (MSX) treatments. The results showed that MtPPRD1 expression is developmentally regulated, induced in the embryo axis immediately before radicle emergence, reaches its maximum expression and declines during the early post-germination phase. Organ specificity studies showed that, except for a low and probably constitutive expression in roots, MtPPRD1 is specifically expressed in the embryo axis. Based on both experimental and in silico studies several putative roles are proposed for MtPPRD1 in Medicago truncatula, this protein can intervene (i) as an LTP in membrane biogenesis and regulation of the intracellular fatty acid pool by binding and transferring fatty acids and phospholipids between membranes, (ii) in the control of a developmental process specific to late germination and to early phases of post-germination, and (iii) and/or pathogen defence.

Respective roles of the glutamine synthetase/glutamate synthase cycle and glutamate dehydrogenase in ammonium and amino acid metabolism during germination and post-germinative growth in the model legume Medicago truncatula

Our objective was to determine the respective roles of the couple glutamine synthetase/glutamate synthase (GS/GOGAT) and glutamate dehydrogenase (GDH) in ammonium and amino acid metabolism during germination and post-germinative growth in the model legume Medicago truncatula Gaertn. For this aim, amino acids were analyzed by HPLC and changes in gene expression of several enzymes involved in N and C metabolism were studied by real-time quantitative reverse transcription-polymerase chain reaction. Among the enzymes studied, GDH showed the highest increase in gene expression (80-fold), specifically in the embryo axis and concomitant with the increase in ammonium content during post-germinative growth. In cotyledons, GDH gene expression was very low. Although in vitro GDH aminating activity was several times higher than its deaminating activity, in vivo 15NH4 incorporation into amino acids was completely inhibited by methionine sulfoximine, a GS inhibitor, indicating that GDH is not involved in ammonium assimilation/detoxification. Changes in the expressions of GS and GOGAT isoforms revealed that GS1b (EC 6.3.1.2) in concert with NADH-dependent GOGAT (EC 1.4.1.14) constitute the major route of assimilation of ammonium derived from reserve mobilization and glutamic acid/glutamine synthesis in germinating M. truncatula seeds. However, during post-germinative growth, although germination was held in darkness, expression of GS2 and Fd-GOGAT (EC 1.4.7.1) increased and expression of GS1b decreased in cotyledons but not in the embryo axis. 2-Oxoglutarate, the substrate of the transamination reaction, was provided by the cytosolic isoform of isocitrate dehydrogenase (EC 1.1.1.42). We suggest that GDH during post-germinative growth, specifically in the developing embryo axis, contributes to ammonium delivery to GS for glutamine synthesis in the absence of primary NO3- assimilation. Interestingly, this reaction also produces reducing power (NADH) in organs deprived of photosynthesis.

Cloning and characterization of HEP21, a new member of the uPAR/Ly6 protein superfamily predominantly expressed in hen egg white

Using two-dimensional (2D)-PAGE, partial protein internal sequencing, and PCR with degenerate primers, we cloned a novel cDNA named HEP21 from hen egg white. The 0.5-kb cDNA encodes a 106 amino acid protein with a cysteine spacing pattern suggesting that HEP21 is a new member of the uPAR/CD59/Ly-6/ snake neurotoxin superfamily. The closest homology of HEP21 is to mouse Ly-6C. Unlike most members of this protein family, HEP21 is not glycosylphosphatidylinositol (GPI)-anchored but is a secreted protein, as indicated by its localization and the presence of a signal peptide in its sequence. Moreover, HEP21 appears as an original member of this protein superfamily because it is predominantly expressed in a tissue, i.e., the oviduct, and especially the magnum where the egg white components are secreted.

QUASIMODO1 encodes a putative membrane-bound glycosyltransferase required for normal pectin synthesis and cell adhesion in Arabidopsis

Pectins are a highly complex family of cell wall polysaccharides. As a result of a lack of specific mutants, it has been difficult to study the biosynthesis of pectins and their role in vivo. We have isolated two allelic mutants, named quasimodo1 (qua1-1 and qua1-2), that are dwarfed and show reduced cell adhesion. Mutant cell walls showed a 25% reduction in galacturonic acid levels compared with the wild type, indicating reduced pectin content, whereas neutral sugars remained unchanged. Immersion immunofluorescence with the JIM5 and JIM7 monoclonal antibodies that recognize homogalacturonan epitopes revealed less labeling of mutant roots compared with the wild type. Both mutants carry a T-DNA insertion in a gene (QUA1) that encodes a putative membrane-bound glycosyltransferase of family 8. We present evidence for the possible involvement of a glycosyltransferase of this family in the synthesis of pectic polysaccharides, suggesting that other members of this large multigene family in Arabidopsis also may be important for pectin biosynthesis. The mutant phenotype is consistent with a central role for pectins in cell adhesion.

Accurate systolic wall thickening by nuclear magnetic resonance imaging with tissue tagging: correlation with sonomicrometers in normal and ischemic myocardium

OBJECTIVES

This study examined whether the correlation of systolic wall thickening (%WT) by nuclear magnetic resonance (NMR) imaging with wall thickening by sonomicrometry (SM) is improved by using a three-dimensional volume element model of the left ventricular wall.

BACKGROUND

Left ventricular wall obliquity with respect to the imaging plane causes overestimation of wall thickness by planar imaging techniques. Wall thickness perpendicular to the endocardial surface can be accurately calculated by three-dimensional reconstruction of left ventricular wall segments.

METHODS

Sonomicrometers were placed transmurally in 11 dogs (left anterior descending artery territory) with an imaging marker, visible on NMR imaging, sewn to the epicardial crystal. Two adjacent NMR short-axis image planes were radially segmented by four perpendicular spin-saturated planes (tags), dividing the myocardium into eight volume elements, one of which contained the sonomicrometer crystal pair. Left ventricular thickness and thickening were calculated by four methods: 1) linear = distance between epicardium and endocardium at midpoint in the segment with the sonomicrometer; 2) planar = area of that segment divided by the mean of the endocardial and epicardial arc lengths; 3) biplanar = average of wall thicknesses calculated by the planar method from the segment with sonomicrometers and the corresponding segment located in the adjacent short-axis imaging plane; and 4) three-dimensional = volume of the element with the sonomicrometers divided by the mean of the endocardial and epicardial surface areas.

RESULTS

Regressions for all methods using pooled data from control periods and during ischemia: Linear %WT = 0.59 + 1.31 SM%WT (r = 0.71, SEE = 0.28, p < 0.0002) Planar %WT = 1.43 + 1.62 SM%WT (r = 0.87, SEE = 0.19, p < 0.0001) Biplanar %WT = 2.09 + 1.46 SM%WT (r = 0.90, SEE = 0.15, p < 0.0001) Three-dimensional %WT = 0.19 + 1.49 SM%WT (r = 0.95, SEE = 0.10, p < 0.0001)

CONCLUSIONS

Nuclear magnetic resonance imaging with tissue tagging allows accurate noninvasive assessment of systolic wall thickening. The three-dimensional volume element approach, by accounting for obliquity between the image plane and the left ventricular wall, provides the strongest correlation between NMR imaging and percent systolic wall thickening by sonomicrometer crystals.

[Contribution of antimyosin antibody myocardial scintigraphy in the diagnosis of acute myocarditis]

The authors report three cases of acute myocarditis: the first patient was a 23 year old woman treated for tuberculosis who presented with rapidly progressive congestive cardiac failure. The second patient was a 52 year old man with atypical chest pain and the third was a 55 year old woman presenting as an acute myocardial infarction. In all three cases, a positive antimyosin antibody myocardial scintigraphy supported the presumptive diagnosis. The authors review the principles of the method and its potential indications, antimyosin antibody scintigraphy being able to demonstrate recent myocardial necrosis but not to identify the cause. The sensitivity of the technique is high (83 to 100% according to the series) but the specificity is much lower (about 55%) compared with endomyocardial biopsy, an investigation which is specific but not very sensitive. Modifications of the antibody and the radioactive tracer used at present should improve the diagnostic value of the technique in the near future.

[Cardiac metastasis disclosed by ventricular tachycardia. Diagnosis by echocardiography and ultrafast tomodensitometry]

The authors report the case of a right ventricular metastasis presenting with ventricular tachycardia and underline the usual diagnostic problems of secondary cardiac tumours, the symptoms of which are often unspecific and late. The appearance of a cardiac arrhythmia in the absence of known cardiac disease should raise the possibility of a cardiac metastasis in patients with malignant disease. The reported case also illustrates the diagnostic value of non-invasive cardiac imaging techniques (echocardiography and ultra-fast computerised tomography) in this context.

Differentiation of tumor from viable myocardium using cardiac tagging with MR imaging

We report the application of myocardial tagging by MR to define tissue planes and differentiate contractile from noncontractile tissue in a neonate with congenital cardiac rhabdomyoma. Using custom-written pulse programming software, six 2 mm thick radiofrequency (RF) slice-selective presaturation pulses (tags) were used to label the chest wall and myocardium in a star pattern in diastole, approximately 60 ms before the R-wave gating trigger. This method successfully delineated the myocardium from noncontractile tumor, providing information that influenced clinical management. This RF tagging technique allowed us to confirm the exact intramyocardial location of a congenital cardiac tumor.

[Enoximone in the hemodynamic evaluation before heart transplantation. A new test]

A better selection of patients referred for cardiac transplantation should lead to better surgical results. The presence of severe and irreversible pulmonary hypertension is an important factor and its pretransplantation assessment requires pharmacodynamic testing with vasodilators and dobutamine. The aim of this study of 10 patients in congestive cardiac failure referred for cardiac transplantation was to evaluate enoximone in this indication by comparing it with sodium nitroprussiate (3 micrograms/kg/mn). Intravenous enoximone (total dose of 1.5 mg/kg) increased the cardiac index (+49%; p less than 0.01), slightly reduced the mean systemic blood pressure (-8%; p less than 0.05) whilst inducing a greater reduction in systemic arterial resistances (-36%; p less than 0.01); the fall in mean blood pressure was less than with sodium nitroprussiate (-23%; p less than 0.01). Myocardial oxygen consumption (rate-pressure product) did not increase in contrast to the effect of dobutamine (+21%; p less than 0.01). There was a significant reduction in pulmonary arteriolar resistances (p less than 0.01) with all three drugs but the interpretation of this response and its prognostic significance in patients with a low cardiac output and persistent pulmonary hypertension are discutable even when pulmonary arteriolar resistances are less than 6 Wood units. The value of using an inotropic agent such as Dobutamine or Enoximone is to unmask fixed pulmonary hypertension which may be missed in patients with low cardiac output even with vasodilator drugs, and also to mimic the haemodynamic result of transplantation. In this indication Enoximone may be used like Dobutamine but with the advantage of not increasing myocardial oxygen consumption and being probably less arrhythmogenic.