Understanding precision nitrogen stress to optimize the growth and lipid content tradeoff in oleaginous green microalgae.

Nitrogen deficiency promotes lipid formation in many microalgae, but also limits growth and lipid productivity. In spite of numerous studies, there is poor understanding of the interactions of growth and lipid content, the time course of lipid accumulation and the magnitude of nitrogen deficiency required to stimulate lipid formation. These relationships were investigated in six species of oleaginous green algae, comparing high and low levels of deficiency. Nitrogen stress typically had disproportionate effects on growth and lipid content, with profound differences among species. Optimally balancing the tradeoffs required a wide range in nitrogen supply rate among species. Some species grew first and then accumulated lipids, while other species grew and accumulated lipids concurrently which resulted in increased lipid productivity. Accumulation of high lipid content generally resulted from a response to minimal stress. The data highlight the tremendous biodiversity that may be exploited to optimally produce lipids with precision nitrogen stress.

B-type natriuretic peptide is an independent predictor of endothelial function in man.

BNP (B-type natriuretic peptide) has been reported to be elevated in preclinical states of vascular damage. To elucidate the relationship between plasma BNP and endothelial function, we have investigated the relationship between BNP and endothelial function in a cohort of subjects comprising healthy subjects as well as at-risk subjects with cardiovascular risk factors. To also clarify the relative contribution of different biological pathways to the individual variation in endothelial function, we have examined the relationship between a panel of multiple biomarkers and endothelial function. A total of 70 subjects were studied (mean age, 58.1±4.6 years; 27% had a history of hypertension and 18% had a history of hypercholesterolaemia). Endothelium-dependent vasodilatation was evaluated by the invasive ACH (acetylcholine)-induced forearm vasodilatation technique. A panel of biomarkers of biological pathways was measured: BNP, haemostatic factors PAI-1 (plasminogen-activator inhibitor 1) and tPA (tissue plasminogen activator), inflammatory markers, including cytokines [hs-CRP (high sensitive C-reactive protein), IL (interleukin)-6, IL-8, IL-18, TNFα (tumour necrosis factor α) and MPO (myeloperoxidase] and soluble adhesion molecules [E-selectin and sCD40 (soluble CD40)]. The median BNP level in the study population was 26.9 pg/ml. Multivariate regression analyses show that age, the total cholesterol/HDL (high-density lipoprotein) ratio, glucose and BNP were independent predictors of endothelial function, and BNP remained an independent predictor (P=0.009) in a binary logistic regression analysis using FBF (forearm blood flow) as a dichotomous variable based on the median value. None of the other plasma biomarkers was independently related to ACH-mediated vasodilatation. In a strategy using several biomarkers to relate to endothelial function, plasma BNP was found to be an independent predictor of endothelial function as assessed by endothelium-dependent vasodilatation in response to ACH.

Global array-based transcriptomics from minimal input RNA utilising an optimal RNA isolation process combined with SPIA cDNA probes.

BACKGROUND: Technical advances in the collection of clinical material, such as laser capture microdissection and cell sorting, provide the advantage of yielding more refined and homogenous populations of cells. However, these attractive advantages are counter balanced by the significant difficulty in obtaining adequate nucleic acid yields to allow transcriptomic analyses. Established technologies are available to carry out global transcriptomics using nanograms of input RNA, however, many clinical samples of low cell content would be expected to yield RNA within the picogram range. To fully exploit these clinical samples the challenge of isolating adequate RNA yield directly and generating sufficient microarray probes for global transcriptional profiling from this low level RNA input has been addressed in the current report. We have established an optimised RNA isolation workflow specifically designed to yield maximal RNA from minimal cell numbers. This procedure obtained RNA yield sufficient for carrying out global transcriptional profiling from vascular endothelial cell biopsies, clinical material not previously amenable to global transcriptomic approaches. In addition, by assessing the performance of two linear isothermal probe generation methods at decreasing input levels of good quality RNA we demonstrated robust detection of a class of low abundance transcripts (GPCRs) at input levels within the picogram range, a lower level of RNA input (50 pg) than previously reported for global transcriptional profiling and report the ability to interrogate the transcriptome from only 10 pg of input RNA. By exploiting an optimal RNA isolation workflow specifically for samples of low cell content, and linear isothermal RNA amplification methods for low level RNA input we were able to perform global transcriptomics on valuable and potentially informative clinically derived vascular endothelial biopsies here for the first time. These workflows provide the ability to robustly exploit ever more common clinical samples yielding extremely low cell numbers and RNA yields for global transcriptomics.

Polymorphisms of the angiotensin converting enzyme gene in relation to intrauterine growth restriction.

The aim of this case-control study was to explore the relation between maternal and infant angiotensin converting enzyme (ACE) activity and its genotypes in uncomplicated term pregnancies (> or =37 weeks) and pregnancies with growth-restricted infants (birthweight at or below the 5th centile). Venous cord bloods and maternal venous samples were obtained for serum ACE activity and ACE genotype. Growth-restricted infants (< or =5th centile) were more likely to be of the DD genotype compared to appropriately grown infants (42 vs. 13%, p = 0.003). There was no significant difference in the frequency of the maternal DD genotype between the two groups (33 vs. 22%, p = 0.43) and similarly no significant differences in the maternal or fetal ACE activities. Within the intrauterine growth restriction (IUGR) group, infants of the DD genotype had higher ACE activity compared to appropriately grown infants (p = 0.03). In conclusion, the DD genotype of the ACE gene appears to be associated with fetal growth and may be a factor in the increased risk of adult onset chronic diseases among growth-restricted infants.

Polymorphisms of the angiotensin converting enzyme gene in early-onset and late-onset pre-eclampsia.

OBJECTIVE: The aim of this study was to investigate differences in maternal and infant ACE genotypes in early-onset and later-onset pre-eclampsia/toxemia (PET). METHODS: We conducted a case-control study of 22 cases of early-onset pre-eclampsia (before 34 weeks gestation), 38 cases of later-onset pre-eclampsia (after 34 weeks gestation), and 108 healthy controls delivered at term (38-40 weeks gestation) within a stable Caucasian population. Maternal venous blood and cord bloods were obtained for serum angiotensin converting enzyme (ACE) activity, ACE genotype, and acid-base status. RESULTS: Mothers who developed early-onset PET were more likely to be homozygous for the deletion allele of the ACE genotype (DD) than mothers with late-onset PET or uncomplicated pregnancies (12/22 (55%) vs. 7/38 (18%) vs. 22/105 (21%), respectively; OR 2.96 [95% confidence intervals (CI) 1.37-6.31]. Infants of mothers with early-onset PET were more likely to be homozygous for the DD genotype than infants of mothers with late-onset PET or controls (7/19 (37%) vs. 9/36 (25%) vs. 11/78 (14%); OR 2.51 (95% CI 1.12-5.61). There were no differences in maternal or infant ACE activities in relation to onset of pre-eclampsia. CONCLUSIONS: Our findings suggest an association between the DD genotype of the ACE gene and early-onset but not later-onset pre-eclampsia which may give a partial explanation for the higher recurrence risk with early-onset pre-eclampsia.

Insulin resistance is highly prevalent and is associated with reduced exercise tolerance in nondiabetic patients with heart failure.

OBJECTIVES: The purpose of this study was to establish the prevalence of insulin resistance (IR) among nondiabetic chronic heart failure (CHF) patients and to seek factors associated with IR in CHF, including the relationship of IR to functional class, exercise capacity, and disease severity in CHF. BACKGROUND: Several lines of evidence suggest that CHF is an IR state. The prevalence of IR in CHF and its relation to CHF have not been fully defined. METHODS: Fasting insulin resistance index (FIRI) was assessed in a cohort of 129 consecutive CHF patients (mean age 69.2 +/- 10.4 years; 76% males; body mass index 27.4 +/- 4.4 kg/m(2)). Patients underwent cardiopulmonary exercise testing and peripheral endothelial function testing by reactive hyperemia peripheral arterial tonometry (RH-PAT). RESULTS: Prevalence of IR as defined by FIRI > or =2.7 was 61% in our cohort of CHF patients. There was a significant correlation between IR and waist circumference (r = 0.37; p < 0.01), serum triglycerides (r = 0.34; p < 0.01), high-density lipoprotein cholesterol (r = -0.22; p = 0.02), and serum leptin (r = 0.39; p = 0.03). Insulin resistance increased significantly with worsening New York Heart Association functional class (p < 0.01). The CHF patients with IR had a significantly lower exercise capacity and peak oxygen consumption than patients with an FIRI <2.7. The RH-PAT ratio was significantly lower in CHF patients with IR compared with CHF patients with an FIRI <2.7 (1.6 +/- 0.3 vs. 2.0 +/- 0.5; p < 0.05). CONCLUSIONS: Insulin resistance is highly prevalent among nondiabetic CHF patients and is associated with decreased exercise capacity in patients with CHF. (Insulin Resistance: Heart Failure; NCT00486967).

Correlation of angiotensin converting enzyme activity and the genotypes of the I/D polymorphism in the ACE gene with preterm birth and birth weight.

OBJECTIVE: Preterm birth remains one of the most challenging areas in obstetrics. The pathogenesis of preterm labor is multifactorial and research on preterm birth has focused principally on infection and inflammatory markers. Recently the focus has turned to potential genetic factors influencing preterm birth. Uteroplacental insufficiency and thrombotic vasculopathy are considered part of the pathogenesis of preterm labor. Investigating the gene expression in the maternal/fetal interface seems of importance to expand our knowledge of the pathophysiology of preterm birth. The renin-angiotensin system (RAS) appears to play an important role in fetal/placental development and uteroplacental circulation. Hence, the aim of this study was to investigate angiotensin converting enzyme (ACE) activity and I/D polymorphisms in the ACE gene in mothers and infants with appropriately grown infants in relation to preterm birth and infant birth weight. STUDY DESIGN: We conducted a cross-sectional study of 113 term pregnancies (> or =37 weeks) and 18 preterm pregnancies (<37 weeks). Umbilical cord bloods (venous and arterial) were obtained from the placenta immediately after delivery for serum ACE activity, ACE genotype analysis of the I/D polymorphism and the acid-base status. Maternal venous samples were obtained just after delivery for analysis of ACE activity and ACE genotype. RESULTS: The distribution of the maternal ACE genotypes was similar for preterm and term births as was maternal ACE activity. Preterm infants were more likely to be of the DD genotype than term infants (7/18 (39%) vs. 11/83 (13%), p=0.02) (adjusted p=0.04). There was no correlation between ACE activity and birth weight (r(2) 0.00, p=0.82). CONCLUSIONS: These findings suggest that the ACE genotype of the infant may influence the risk of preterm birth among appropriately grown fetuses.

The functional consequence of the Glu298Asp polymorphism of the endothelial nitric oxide synthase gene in young healthy volunteers.

OBJECTIVE: To assess the role of the endothelial nitric oxide synthase (eNOS) gene variant as a risk factor for atherosclerosis we sought to investigate whether the Glu298Asp polymorphism of the eNOS gene is associated with functional changes in the endothelium in healthy volunteers. METHODS: Endothelial function was assessed in 68 normal volunteers (ages 18-44 years) by bilateral forearm venous occlusion plethysmography with intraarterial infusions of increasing doses of acetylcholine for endothelial-dependent vasodilation and, with sodium nitroprusside and verapamil for endothelial-independent vasodilation. Blood was genotyped by polymerase chain reaction and BanII digestion. RESULTS: Asp homozygotes (TT) had a decreased vasodilatory response to acetylcholine [forearm blood flow (FBF) ratio between infused and control arm, 2.82 +/- 1.10] when compared to GG variant (FBF ratio to acetylcholine, 3.97 +/- 1.90, p= 0.04) and to a certain extent, the GT variant (FBF ratio to acetylcholine, 3.79 +/- 2.28, p= 0.07). There was no effect of eNOS genotype on the response to the endothelial-independent vasodilators-sodium nitroprusside and verapamil. CONCLUSIONS: Our data show that carriage of the Asp298 variant of the eNOS gene is associated with a blunted endothelial-dependent vasodilation in healthy volunteers. These findings support a genetically determined modulation of endothelial dysfunction, a phenotype of early atherosclerosis in humans.

Effect of spironolactone on C-reactive protein levels in patients with heart disease.

Animal evidence shows that aldosterone is pro-inflammatory and that aldosterone blockade is anti-inflammatory. Therefore part of the beneficial effect of aldosterone blockade that might contribute to it reducing mortality could be an anti-inflammatory effect. However, there are no previous data on whether aldosterone blockade is anti-inflammatory in man. We performed 4 separate studies to investigate whether spironolactone treatment would reduce levels of C-reactive protein (CRP), a marker of inflammation, in serum samples taken from patients suffering from different degrees of heart failure. We found in all 4 studies that spironolactone had no significant effect compared with placebo, on CRP levels in these patients. These studies provide evidence against the hypothesis that the clinical benefits produced by aldosterone blockade are due to it having anti-inflammatory effects.