Metabolite Profiles of Maize Leaves in Drought, Heat, and Combined Stress Field Trials Reveal the Relationship between Metabolism and Grain Yield.

The development of abiotic stress-resistant cultivars is of premium importance for the agriculture of developing countries. Further progress in maize (Zea mays) performance under stresses is expected by combining marker-assisted breeding with metabolite markers. In order to dissect metabolic responses and to identify promising metabolite marker candidates, metabolite profiles of maize leaves were analyzed and compared with grain yield in field trials. Plants were grown under well-watered conditions (control) or exposed to drought, heat, and both stresses simultaneously. Trials were conducted in 2010 and 2011 using 10 tropical hybrids selected to exhibit diverse abiotic stress tolerance. Drought stress evoked the accumulation of many amino acids, including isoleucine, valine, threonine, and 4-aminobutanoate, which has been commonly reported in both field and greenhouse experiments in many plant species. Two photorespiratory amino acids, glycine and serine, and myoinositol also accumulated under drought. The combination of drought and heat evoked relatively few specific responses, and most of the metabolic changes were predictable from the sum of the responses to individual stresses. Statistical analysis revealed significant correlation between levels of glycine and myoinositol and grain yield under drought. Levels of myoinositol in control conditions were also related to grain yield under drought. Furthermore, multiple linear regression models very well explained the variation of grain yield via the combination of several metabolites. These results indicate the importance of photorespiration and raffinose family oligosaccharide metabolism in grain yield under drought and suggest single or multiple metabolites as potential metabolic markers for the breeding of abiotic stress-tolerant maize.

Arabidopsis BPM proteins function as substrate adaptors to a cullin3-based E3 ligase to affect fatty acid metabolism in plants.

Regulation of transcriptional processes is a critical mechanism that enables efficient coordination of the synthesis of required proteins in response to environmental and cellular changes. Transcription factors require accurate activity regulation because they play a critical role as key mediators assuring specific expression of target genes. In this work, we show that cullin3-based E3 ligases have the potential to interact with a broad range of ethylene response factor (ERF)/APETALA2 (AP2) transcription factors, mediated by Math-BTB/POZ (for Meprin and TRAF [tumor necrosis factor receptor associated factor] homolog)-Broad complex, Tramtrack, Bric-a-brac/Pox virus and Zinc finger) proteins. The assembly with an E3 ligase causes degradation of their substrates via the 26S proteasome, as demonstrated for the wrinkled1 ERF/AP2 protein. Furthermore, loss of Math-BTB/POZ proteins widely affects plant development and causes altered fatty acid contents in mutant seeds. Overall, this work demonstrates a link between fatty acid metabolism and E3 ligase activities in plants and establishes CUL3-based E3 ligases as key regulators in transcriptional processes that involve ERF/AP2 family members.

An integrated functional approach to dissect systemic responses in maize to arbuscular mycorrhizal symbiosis.

Most terrestrial plants benefit from the symbiosis with arbuscular mycorrhizal fungi (AMF) mainly under nutrient-limited conditions. Here the crop plant Zea mays was grown with and without AMF in a bi-compartmented system separating plant and phosphate (Pi) source by a hyphae-permeable membrane. Thus, Pi was preferentially taken up via the mycorrhizal Pi uptake pathway while other nutrients were ubiquitously available. To study systemic effects of mycorrhizal Pi uptake on leaf status, leaves of these plants that display an increased biomass in the presence of AMF were subjected to simultaneous ionomic, transcriptomic and metabolomic analyses. We observed robust changes of the leaf elemental composition, that is, increase of P, S and Zn and decrease of Mn, Co and Li concentration in mycorrhizal plants. Although changes in anthocyanin and lipid metabolism point to an improved P status, a global increase in C versus N metabolism highlights the redistribution of metabolic pools including carbohydrates and amino acids. Strikingly, an induction of systemic defence gene expression and concomitant accumulation of secondary metabolites such as the terpenoids alpha- and beta-amyrin suggest priming of mycorrhizal maize leaves as a mycorrhiza-specific response. This work emphasizes the importance of AM symbiosis for the physiological status of plant leaves and could lead to strategies for optimized breeding of crop species with high growth potential.

Identification of the 2-hydroxyglutarate and isovaleryl-CoA dehydrogenases as alternative electron donors linking lysine catabolism to the electron transport chain of Arabidopsis mitochondria.

The process of dark-induced senescence in plants is relatively poorly understood, but a functional electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) complex, which supports respiration during carbon starvation, has recently been identified. Here, we studied the responses of Arabidopsis thaliana mutants deficient in the expression of isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase to extended darkness and other environmental stresses. Evaluations of the mutant phenotypes following carbon starvation induced by extended darkness identify similarities to those exhibited by mutants of the ETF/ETFQO complex. Metabolic profiling and isotope tracer experimentation revealed that isovaleryl-CoA dehydrogenase is involved in degradation of the branched-chain amino acids, phytol, and Lys, while 2-hydroxyglutarate dehydrogenase is involved exclusively in Lys degradation. These results suggest that isovaleryl-CoA dehydrogenase is the more critical for alternative respiration and that a series of enzymes, including 2-hydroxyglutarate dehydrogenase, plays a role in Lys degradation. Both physiological and metabolic phenotypes of the isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase mutants were not as severe as those observed for mutants of the ETF/ETFQO complex, indicating some functional redundancy of the enzymes within the process. Our results aid in the elucidation of the pathway of plant Lys catabolism and demonstrate that both isovaleryl-CoA dehydrogenase and 2-hydroxyglutarate dehydrogenase act as electron donors to the ubiquinol pool via an ETF/ETFQO-mediated route.

Development of a Novel Enzyme-Linked Immunosorbent Assay and Lateral Flow Test System for Improved Serodiagnosis of Visceral Leishmaniasis in Different Areas of Endemicity.

Visceral leishmaniasis (VL) is caused by protozoan parasites of the Leishmania donovani complex and is one of the most prominent vector-borne infectious diseases with epidemic and mortality potential if not correctly diagnosed and treated. East African countries suffer from a very high incidence of VL, and although several diagnostic tests are available for VL, diagnosis continues to represent a big challenge in these countries due to the lack of sensitivity and specificity of current serological tools. Based on bioinformatic analysis, a new recombinant kinesin antigen from Leishmania infantum (rKLi8.3) was developed. The diagnostic performance of rKLi8.3 was evaluated by enzyme-linked immunosorbent assay (ELISA) and lateral flow test (LFT) on a panel of sera from Sudanese, Indian, and South American patients diagnosed with VL or other diseases, including tuberculosis, malaria, and trypanosomiasis. The diagnostic accuracy of rKLi8.3 was compared with rK39 and rKLO8 antigens. The VL-specific sensitivity of rK39, rKLO8, and rKLi8.3 ranged from 91.2% over 92.4% to 97.1% and specificity ranged from 93.6% over 97.6% to 99.2%, respectively. In India, all tests showed a comparable specificity of 90.9%, while the sensitivity ranged from 94.7% to 100% (rKLi8.3). In contrast to commercial serodiagnostic tests, rKLi8.3-based ELISA and LFT showed improved sensitivity and no cross-reactivity with other parasitic diseases. Thus, rKLi8.3-based ELISA and LFT offer improved VL serodiagnostic efficiency in East Africa and other areas of endemicity. IMPORTANCE Reliable and field suitable serodiagnosis of visceral leishmaniasis (VL) in East Africa has until now been a big challenge due to low sensitivity and cross-reactivity with other pathogens. To improve VL serodiagnosis, a new recombinant kinesin antigen from Leishmania infantum (rKLi8.3) was developed and tested with a panel of sera from Sudanese, Indian, and South American patients diagnosed with VL or other infectious diseases. Both prototype rKLi8.3-based enzyme-linked immunosorbent assay (ELISA) and lateral flow test (LFT) showed improved sensitivity and no cross-reactivity with other parasitic diseases. Thus, rKLi8.3-based ELISA and LFT offer substantially increased diagnostic efficiency for VL in East Africa and other areas of endemicity, compared to currently commercially available serodiagnostic tests.

Enhanced levels of vitamin B(6) increase aerial organ size and positively affect stress tolerance in Arabidopsis.

Vitamin B6 is an essential nutrient in the human diet derived primarily from plant sources. While it is well established as a cofactor for numerous metabolic enzymes, more recently, vitamin B6 has been implicated as a potent antioxidant. The de novo vitamin B6 biosynthesis pathway in plants has recently been unraveled and involves only two proteins, PDX1 and PDX2. To provide more insight into the effect of the compound on plant development and its role as an antioxidant, we have overexpressed the PDX proteins in Arabidopsis, generating lines with considerably higher levels of the vitamin in comparison with other recent attempts to achieve this goal. Interestingly, it was possible to increase the level of only one of the two catalytically active PDX1 proteins at the protein level, providing insight into the mechanism of vitamin B6 homeostasis in planta. Vitamin B6 enhanced lines have considerably larger vegetative and floral organs and although delayed in pre-reproductive development, do not have an altered overall morphology. The vitamin was observed to accumulate in seeds and the enhancement of its levels was correlated with an increase in their size and weight. This phenotype is predominantly a consequence of embryo enlargement as reflected by larger cells. Furthermore, plants that overaccumulate the vitamin have an increased tolerance to oxidative stress providing in vivo evidence for the antioxidant functionality of vitamin B6. In particular, the plants show an increased resistance to paraquat and photoinhibition, and they attenuate the cell death response observed in the conditional flu mutant.

OPTIMAS-DW: a comprehensive transcriptomics, metabolomics, ionomics, proteomics and phenomics data resource for maize.

BACKGROUND: Maize is a major crop plant, grown for human and animal nutrition, as well as a renewable resource for bioenergy. When looking at the problems of limited fossil fuels, the growth of the world's population or the world's climate change, it is important to find ways to increase the yield and biomass of maize and to study how it reacts to specific abiotic and biotic stress situations. Within the OPTIMAS systems biology project maize plants were grown under a large set of controlled stress conditions, phenotypically characterised and plant material was harvested to analyse the effect of specific environmental conditions or developmental stages. Transcriptomic, metabolomic, ionomic and proteomic parameters were measured from the same plant material allowing the comparison of results across different omics domains. A data warehouse was developed to store experimental data as well as analysis results of the performed experiments. DESCRIPTION: The OPTIMAS Data Warehouse (OPTIMAS-DW) is a comprehensive data collection for maize and integrates data from different data domains such as transcriptomics, metabolomics, ionomics, proteomics and phenomics. Within the OPTIMAS project, a 44K oligo chip was designed and annotated to describe the functions of the selected unigenes. Several treatment- and plant growth stage experiments were performed and measured data were filled into data templates and imported into the data warehouse by a Java based import tool. A web interface allows users to browse through all stored experiment data in OPTIMAS-DW including all data domains. Furthermore, the user can filter the data to extract information of particular interest. All data can be exported into different file formats for further data analysis and visualisation. The data analysis integrates data from different data domains and enables the user to find answers to different systems biology questions. Finally, maize specific pathway information is provided. CONCLUSIONS: With OPTIMAS-DW a data warehouse for maize was established, which is able to handle different data domains, comprises several analysis results that will support researchers within their work and supports systems biological research in particular. The system is available at http://www.optimas-bioenergy.org/optimas_dw.

Analysis of a range of catabolic mutants provides evidence that phytanoyl-coenzyme A does not act as a substrate of the electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase complex in Arabidopsis during dark-induced senescence.

The process of dark-induced senescence in plants is not fully understood, however, the functional involvement of an electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO), has been demonstrated. Recent studies have revealed that the enzymes isovaleryl-coenzyme A (CoA) dehydrogenase and 2-hydroxyglutarate dehydrogenase act as important electron donors to this complex. In addition both enzymes play a role in the breakdown of cellular carbon storage reserves with isovaleryl-CoA dehydrogenase being involved in degradation of the branched-chain amino acids, phytol, and lysine while 2-hydroxyglutarate dehydrogenase is exclusively involved in lysine degradation. Given that the chlorophyll breakdown intermediate phytanoyl-CoA accumulates dramatically both in knockout mutants of the ETF/ETFQO complex and of isovaleryl-CoA dehydrogenase following growth in extended dark periods we have investigated the direct importance of chlorophyll breakdown for the supply of carbon and electrons during this process. For this purpose we isolated three independent Arabidopsis (Arabidopsis thaliana) knockout mutants of phytanoyl-CoA 2-hydroxylase and grew them under the same extended darkness regime as previously used. Despite the fact that these mutants accumulated phytanoyl-CoA and also 2-hydroxyglutarate they exhibited no morphological changes in comparison to the other mutants previously characterized. These results are consistent with a single entry point of phytol breakdown into the ETF/ETFQO system and furthermore suggest that phytol is not primarily metabolized by this pathway. Furthermore analysis of isovaleryl-CoA dehydrogenase/2-hydroxyglutarate dehydrogenase double mutants generated here suggest that these two enzymes essentially account for the entire electron input via the ETF complex.

Elastin haploinsufficiency results in progressive aortic valve malformation and latent valve disease in a mouse model.

RATIONALE: Elastin is a ubiquitous extracellular matrix protein that is highly organized in heart valves and arteries. Because elastic fiber abnormalities are a central feature of degenerative valve disease, we hypothesized that elastin-insufficient mice would manifest viable heart valve disease. OBJECTIVE: To analyze valve structure and function in elastin-insufficient mice (Eln(+/-)) at neonatal, juvenile, adult, and aged adult stages. METHODS AND RESULTS: At birth, histochemical analysis demonstrated normal extracellular matrix organization in contrast to the aorta. However, at juvenile and adult stages, thin elongated valves with extracellular matrix disorganization, including elastin fragment infiltration of the annulus, were observed. The valve phenotype worsened by the aged adult stage with overgrowth and proteoglycan replacement of the valve annulus. The progressive nature of elastin insufficiency was also shown by aortic mechanical testing that demonstrated incrementally abnormal tensile stiffness from juvenile to adult stages. Eln(+/-) mice demonstrated increased valve interstitial cell proliferation at the neonatal stage and varied valve interstitial cell activation at early and late stages. Gene expression profile analysis identified decreased transforming growth factor-beta-mediated fibrogenesis signaling in Eln(+/-) valve tissue. Juvenile Eln(+/-) mice demonstrated normal valve function, but progressive valve disease (predominantly aortic regurgitation) was identified in 17% of adult and 70% of aged adult Eln(+/-) mice by echocardiography. CONCLUSIONS: These results identify the Eln(+/-) mouse as a model of latent aortic valve disease and establish a role for elastin dysregulation in valve pathogenesis.

[Extraction of diseased mandibular incisors in the guinea pig (Cavia porcellus) via ventral mandibular trepanation]. / Extraktion erkrankter Unterkieferinzisivi beim Meerschweinchen (Cavia porcellus) via ventraler Mandibulatrepanation.

OBJECTIVE: This retrospective study describes the use of ventral mandibular trepanation for extraction of diseased mandibular incisors in guinea pigs and evaluates the clinical outcome. MATERIAL AND METHODS: In 40 guinea pigs with abnormal feed intake, at least one mandibular incisor was extracted via ventral mandibular trepanation. The diagnosis of primary mandibular incisor disease was based on the findings of the clinical general examination and intraoral and radiographic examination under general anesthesia. Following the procedure radiographs were taken and the patients were monitored and cared for as inpatients until discharge. Regular re-examinations were undertaken in order to assess and treat the surgical sites. RESULTS: A total of 42 altered mandibular incisors were extracted via ventral mandibular trepanation. Macrodonts (25/42) and periapical and alveolar changes (8/42) were the main reasons for extraction. Tooth residuals of unknown etiology (4/42) as well as such resulting from failed conventional extraction attempt using luxators (3/42) and traumatically loosened incisors (2/42) were also extracted. Tooth-associated jaw abscesses were found in 40 % of the guinea pigs. In addition, 40 % of the animals presented secondary elongation of the molars requiring occlusal equilibration. In all patients, it was possible to completely remove the altered incisors or residuals. On average, independent feed intake was observed 2 days after surgery and the animals were discharged. Complete healing of the surgical site was observed on average after 39 days (minimum 9 days, maximum 98 days). A total of 22 animals were evaluated 6 months following surgery and showed no further tooth-associated complaints. CONCLUSION AND CLINICAL RELEVANCE: Ventral mandibular trepanation allows diseased mandibular incisors in guinea pigs to be removed entirely within one surgery and thus represents a curative procedure. Unlike the conventional extraction with luxators, it does not bear the risk of tooth fractures resulting in tooth fragments remaining in the alveolus.

Aptamer-Modified Nanoparticles in Medical Applications.

Since aptamers have been selected against a broad range of target structures of medical interest and nanoparticles are available with diverse properties, aptamer-modified nanoparticles can be used in various diagnostic and therapeutic applications. While the aptamer is responsible for specificity and affinity of the conjugate, the nanoparticles' function varies from signal generation in diagnostic approaches to drug loading in drug delivery systems. Within this chapter different medical applications of aptamer-modified nanoparticles will be summarized and underlying principles will be described.

Production of polycaprolactone nanoparticles with hydrodynamic diameters below 100 nm.

Cancer is a worldwide increasing burden and its therapy is often challenging and causes severe side effects in healthy tissue. If drugs are loaded into nanoparticles, side effects can be reduced, and efficiency can be increased via the enhanced permeability and retention effect. This effect is based on the fact that nanoparticles with sizes from 10 to 200 nm can accumulate in tumor tissue due to their leaky vasculature. In this work, we produced polycaprolactone (PCL) in the sizes 1.8, 5.4, and 13.6 kDa and were able to produce spherical shaped nanoparticles with mean diameters of 64 ± 19 nm out of the PCL5.4 and 45 ± 8 nm out of the PCL13.6 reproducibly. By encapsulation of paclitaxel the diameter of that nanoparticles did not increase, and we were able to encapsulate 73 ± 7 fmol paclitaxel per 1000 particles in the PCL5.4-nanoparticles and 35 ± 8 fmol PTX per 1000 PCL13.6-nanoparticles. Furthermore, we coupled the aptamer S15 to preformed PCL5.4-nanoparticles resulting in particles with a hydrodynamic diameter of 153 nm. This offers the opportunity to use these nanoparticles for targeted drug delivery.

Development of Aptamer-Based TID Assays Using Thermophoresis and Microarrays.

Aptamers are single-stranded oligonucleotides which can be used as alternative recognition elements for protein detection, because aptamers bind their targets with a high affinity similar to antibodies. Due to the targetinduced conformational changes of aptamers, these oligonucleotides can be applied in various biosensing platforms. In this work, aptamers directed against the vascular endothelial growth factor (VEGF) were used as a model system. VEGF plays a key role in physiological angiogenesis and vasculogenesis. Furthermore, VEGF is involved in the development and growth of cancer and other diseases like agerelated macular degeneration, rheumatoid arthritis, diabetes mellitus, and neurodegenerative disorders. Detecting the protein biomarker VEGF is therefore of great importance for medical research and diagnostics. In this research, VEGFbinding aptamers were investigated for the systematic development of a targetinduced dissociation (TID) assay utilizing thermophoresis and microarrays. The established aptamer-microarray allowed for the detection of 0.1 nM of VEGF. Furthermore, the systematic development of the TID method using the VEGF model protein could help to develop further TID assays for the detection of various protein biomarkers.

Subclinical systolic dysfunction in pediatric patients with chronic kidney disease.

OBJECTIVES: Midwall shortening (mwSF) is thought to be a more accurate measure of myocardial performance in the presence of left ventricular hypertrophy (LVH). We examined mwSF in pediatric patients with varying degrees of chronic kidney disease (CKD). STUDY DESIGN: Fifty-seven children with CKD stages 2 to 4, 25 who were undergoing hemodialysis and 49 who were transplant recipients, were compared with 35 healthy control subjects. Left ventricular (LV) geometry and indices of LV function were assessed echocardiographically. RESULTS: There were no significant differences in LV contractility or endocardial shortening fraction between patients and control subjects. Yet, patients undergoing hemodialysis had significantly lower mwSF compared with control subjects (P < .01) and patients with stage 2 to 4 CKD (P < .01). Renal transplant patients had lower mwSF compared with control subjects (P < .01). The prevalence of abnormal mwSF (ie, <16) was significantly higher in patients undergoing hemodialysis (40%) compared with patients who were renal transplant recipeints (12%) and patients with CKD stages 2 to 4 (9%; P = .03). With stepwise regression, mwSF was demonstrated to be predicted by using relative wall thickness (P < .0001), dialysis group (P = .005), and endocardial shortening fraction (P = .001; model R(2) = 0.86). CONCLUSIONS: Children undergoing maintenance hemodialysis and children with concentric LVH have subclinical systolic dysfunction, which might be an indicator for the development of more severe cardiac disease.

TGF-beta1 mediates the hypertrophic cardiomyocyte growth induced by angiotensin II.

Angiotensin II (Ang II), a potent hypertrophic stimulus, causes significant increases in TGFb1 gene expression. However, it is not known whether there is a causal relationship between increased levels of TGF-beta1 and cardiac hypertrophy. Echocardiographic analysis revealed that TGF-beta1-deficient mice subjected to chronic subpressor doses of Ang II had no significant change in left ventricular (LV) mass and percent fractional shortening during Ang II treatment. In contrast, Ang II-treated wild-type mice showed a >20% increase in LV mass and impaired cardiac function. Cardiomyocyte cross-sectional area was also markedly increased in Ang II-treated wild-type mice but unchanged in Ang II-treated TGF-beta1-deficient mice. No significant levels of fibrosis, mitotic growth, or cytokine infiltration were detected in Ang II-treated mice. Atrial natriuretic factor expression was approximately 6-fold elevated in Ang II-treated wild-type, but not TGF-beta1-deficient mice. However, the alpha- to beta-myosin heavy chain switch did not occur in Ang II-treated mice, indicating that isoform switching is not obligatorily coupled with hypertrophy or TGF-beta1. The Ang II effect on hypertrophy was shown not to result from stimulation of the endogenous renin-angiotensis system. These results indicate that TGF-beta1 is an important mediator of the hypertrophic growth response of the heart to Ang II.

Diastolic filling abnormalities in children with essential hypertension.

OBJECTIVE: To evaluate whether essential hypertension impacts diastolic function in children. STUDY DESIGN: In this cross-sectional study, patients with essential hypertension (n = 50) were compared with a normotensive group (n = 53). Echocardiographic assessment of diastolic function included measures derived from transmitral, color M-mode, and tissue Doppler interrogation. Cardiac dimensions, wall thickness, geometry, and systolic function were also assessed. Multiple linear regression analysis was performed to identify predictors of altered diastolic function. RESULTS: Diastolic filling abnormalities were found in 36% of the children with blood pressure elevation. Those subjects with concentric hypertrophy were more significantly affected. Abnormalities in indices reflective of left ventricular (LV) relaxation occurred more commonly (39%) than those of LV compliance (33%). Elevated indexed LV mass was found to be the most significant independent predictor of diastolic filling abnormalities. CONCLUSIONS: LV diastolic filling abnormalities were found in one-third of the pediatric subjects with essential hypertension. Whether these changes represent an adaptive or maladaptive response requires further study.

Cardiac-specific IGF-1 expression attenuates dilated cardiomyopathy in tropomodulin-overexpressing transgenic mice.

To test the hypothesis that early interventional treatment with insulin-like growth factor-1 (IGF-1) alleviates subsequent development of dilated cardiomyopathy, cardiac-specific IGF-1 expression was introduced by selective cross-breeding into a transgenic mouse model of heart failure that displays phenotypic characteristics of severe dilation. Hemodynamic, structural, and cellular parameters of the heart were compared between nontransgenic, tropomodulin-overexpressing cardiomyopathic, and the hybrid tropomodulin/IGF-1-overexpressing mice. Beneficial effects of IGF-1 were apparent by multiple indices of cardiac structure and function, including normalization of heart mass, anatomy, hemodynamics, and apoptosis. IGF-1 expression also acted as a proliferative stimulus as evidenced by calculated increases in myocyte number as well as expression of Ki67, a nuclear marker of cellular replication. Cellular analyses revealed that IGF-1 inhibited characteristic cardiomyocyte elongation in dilated hearts and restored calcium dynamics comparable to that observed in normal cells. Collectively, these results provide novel information regarding the ability of IGF-1 to inhibit progression of cardiomyopathic disease in a defined model system and suggest that heart failure may benefit from early interventional IGF-1 treatment.

Abnormal carotid artery structure and function in children and adolescents with successful renal transplantation.

BACKGROUND: Abnormal carotid artery compliance and increased intima-media thickness (IMT), markers of early atherosclerosis, are prevalent in adults with chronic kidney failure. However, little is known about the extent of these abnormalities in children after transplantation. METHODS AND RESULTS: Thirty-one children (age, 14.5+/-4.1 years) with renal transplant (estimated glomerular filtration rate, 78.1+/-24.5 mL/min per 1.73 m2; range, 44 to 128 mL/min per 1.73 m2) and 33 age- and sex-matched control subjects had ultrasound of the carotid artery, echocardiography, and ambulatory blood pressure monitoring (transplant patients only). IMT was measured, and distensibility and stiffness parameter (beta) were calculated to assess carotid artery structure and function. The results were correlated with demographic, clinical, and biochemical variables. Compared with control subjects, children with transplant had higher IMT (P=0.03) and beta (P<0.0001) and lower distensibility (P<0.001). In multiple regression analysis, increased IMT in children who had received transplants was associated with higher mean office systolic blood pressure taken within 1 year before the study (R2=0.19, P=0.024) and receipt of >1 transplant (R2=0.16, P=0.02). Worse distensibility and beta were significantly associated with higher daytime systolic blood pressure load calculated from ambulatory blood pressure and receipt of cadaveric kidney. When number of antihypertensives was added to the models, only higher number of blood pressure medications independently predicted abnormal distensibility (R2=0.38, P=0.002) and beta (R2=0.25, P=0.016). CONCLUSIONS: Carotid arteriopathy is present in children with successful renal transplant and is associated with hypertension. The results suggest that these children might be at risk for accelerated atherosclerosis and premature cardiovascular disease.

Left ventricular mass and systolic performance in pediatric patients with chronic renal failure.

BACKGROUND: Children with chronic renal disease have a high prevalence of left ventricular hypertrophy (LVH), which is thought to be adaptive to improve contractility and lower wall stress in the face of increased afterload and preload. The aim of this study was to determine the association between LV mass, LV performance, and LV contractility in children with chronic renal insufficiency (CRI) and children undergoing chronic dialysis. METHODS AND RESULTS: Twenty-five children with CRI, 12 undergoing chronic dialysis, and 24 controls had echocardiographic evaluation during rest and peak exercise. LV performance was assessed by calculation of shortening fraction and heart rate-corrected velocity of circumferential fiber shortening (VCF). Contractility (VCF difference) was determined based on the relation between VCF and end-systolic wall stress. Contractile reserve was assessed by the difference between contractility at rest and peak exercise. The dialysis group had higher LVM index than the group with CRI (42.9+/-10.3 versus 29.9+/-9.4 g/m(2.7), P<0.001). Both groups had higher LVM index compared with controls (22.2+/-6.1 g/m(2.7), P<0.001). At rest, the CRI and dialysis groups had significantly higher VCF(c) (P<0.001) and VCF difference (P<0.05) and significantly lower wall stress (P<0.01) compared with the control group. Dialysis patients had significantly lower contractile reserve compared with the control group (P<0.03). CONCLUSIONS: These results indicate that children with CRI and undergoing chronic dialysis have increased LVM, LV performance, and contractility at rest. However, dialysis patients have diminished contractile reserve during exercise, which might be an indicator for the development of more severe systolic dysfunction over time.

Left ventricular function in children with sleep-disordered breathing.

Severe obstructive sleep apnea in children leads to congestive heart failure. We studied the early changes in left ventricular function across a range of severity of the disorder. A dose-dependent decrease in diastolic function with increased severity of obstructive apnea was demonstrated.