Gene polymorphisms of the renin-angiotensin-aldosterone system and essential arterial hypertension in childhood

In order to investigate the contribution of candidate genes in the renin-angiotensin-aldosterone system (RAAS) in pathogenesis of essential arterial hypertension (EAH), the I/D polymorphism of ACE gene, the M235T polymorphism of the angiotensinogen gene, and the angiotensin II type 1 receptor (AGT,R) A1166C gene polymorphism in a group of children with EAH were analyzed. Fifty-scven children, aged 8-19 years. with the diagnosis of EAH were included in the association study and were compared with 57 subjects with normal blood pressure (the control group). Arterial hypertension was defined as systolic/diastolic blood pressure measurements higher than 95 age-gender-height percentile of the adopted reference values. A trend was found towards an association between the M235T angiotensinogen gene polymorphism and EAH in childhood in a dominant model (odds ratio (OR) 2.1; 95% confidence interval (CI) 0.9-5.1; P = 0.077), whereas the authors failed to demonstrate an association between the ACE I/D gene polymorphism, or the A1166C AGT1R gene polymorphism and EAH in childhood. Additionally, evidence was found of interaction between the angiotensinogen-TT genotype and obesity on the risk of EAH in childhood (OR 19.3; 95% CI 1.1-77.3; P = 0.014). In conclusion, the M235T angiotensinogen gene polymorphism is considered alone as well as in interaction with obesity to be risk factors for EAH in childhood.     

Probing sesquiterpene hydroxylase activities in a coupled assay with terpene synthases

5-epi-Aristolochene dihydroxylase (EAH) catalyzes unique stereo- and regiospecific hydroxylations of a bicyclic sesquiterpene hydrocarbon to generate capsidiol. To define functional and mechanistic features of the EAH enzyme, the utility of a coupled assay using readily available sesquiterpene synthases and microsomes from yeast overexpressing the EAH enzyme was determined. Capsidiol and deoxycapsidiol biosyntheses were readily measured in coupled assays consisting of 5-epi-aristolochene synthase and EAH as determined by the incorporation of radiolabeled farnesyl diphosphate into thin-layer chromatography-isolated products and verified by gas chromatography-mass spectrometry analysis. The assays were dependent on the amounts of synthase and hydroxylase protein added, the incubation times, and the presence of nicotinamide adenine dinucleotide phosphate. The utility of this coupled assay was extended by examining the relative efficiency of the EAH enzyme to catalyze hydroxylations of different sesquiterpene skeletons generated by other terpene synthases.     

Eating in the Absence of Hunger: A Genetic Marker for Childhood Obesity in Prepubertal Boys?

Objective: Eating in the absence of hunger (EAH) may be a behavioral trait through which obesity‐promoting genes promote positive energy balance. The primary aim of this study was to compare children born at high vs. low risk for obesity with respect to EAH at 5 years of age. Research Methods and Procedures: This was an observational investigation of families enrolled in the University of Pennsylvania and The Children's Hospital of Philadelphia's Infant Growth Study. Five‐year‐old children born at high (N = 28) or low (N = 25) risk for obesity on the basis of maternal prepregnancy body weight were evaluated at a hospital‐based laboratory. Children consumed 11 snack foods ad libitum after consuming an ad libitum dinner and reporting fullness. Parents reported on snack foods at home and their own eating styles. Nutritive sucking at 3 months of age was evaluated by computerized apparatus. Results: EAH in high‐risk boys (mean ± standard error = 326 ± 66 kJ] was more than twice that of low‐risk boys (mean ± standard error = 151 ± 39 kJ), p = 0.03. Among girls, there was a trend for EAH to be associated with increased parental limitations on daughter snack food consumption at home (p = 0.06). EAH was unrelated to 3‐month sucking behavior. Discussion: Genes that promote childhood obesity may partially exert their influence through EAH, an effect that was limited to boys born at risk for obesity. The unique influences of genes and home environment on this trait should be disaggregated in subsequent studies.     

Incidence of exercise-associated hyponatremia during a high-altitude 161-km ultramarathon

[Purpose]Exercise-associated hyponatremia (EAH) is a well-known condition among endurance athletes at low altitudes. The incidence of EAH during ultramarathons at high altitudes warrants further investigation. This prospective observational study was conducted on the participants of the Leadville Trail 100 run, a 161-km race held at a high altitude (2,800 m-3,840 m).[Methods]Venous blood samples were collected before and immediately after the race. The participants completed an electronic survey after the race. Our main outcome measure was the post-race serum sodium ([Na⁺]) level.[Results]Of the 672 athletes who started the race, 351 (52%) successfully completed the event within the 30-hour cut-off. Post-race blood samples were collected from 84 runners (66 finishers). Both pre- and post-race blood samples were collected from 37 participants. Twenty percent of the post-race participants had EAH. Only one post-race participant had a [Na⁺] level of <130 mmol/L. All participants with EAH were asymptomatic. One participant had an abnormal pre-race [Na⁺] level (134 mmol/L). Female participants had a significantly higher rate of EAH than male participants (40% vs. 16%; p=0.039). Age, body mass index, weight changes, race completion status, nonsteroidal anti-inflammatory drug use, and urine specific gravity were not associated with the development of EAH. Lower postrace [Na⁺] levels were associated with higher serum creatine kinase values (R²=0.1, p<0.005).[Conclusion]High altitude (3,840 m peak) does not appear to enhance the incidence of EAH after an ultramarathon footrace. This suggests that ambient temperature (low temperatures reduce risk), sex (female predilection), endurance running, and overhydration are more prominent risk factors for EAH than high altitude.     

Association of T3111C polymorphism in 3'-untranslated region of the CLOCK gene with the risk of essential arterial hypertension and coronary artery disease in the Russian population Karelia

Allele and genotype distributions of the T3111C polymorphism in 3'-untranslated region of the CLOCKgene were examined in the groups of Russian patients with essential arterial hypertension (EAH) and coronary artery disease (CAD), and in control group of Russia residents of the Republic of Karelia. The genotype frequency distributions of the polymorphism examined in the EAH and CAD patients were statistically significantly different from that in the individuals without clinical signs of these diseases. The CC genotype frequency in EAH and CAD males was higher, and in the corresponding females it was lower than in males and females from the control group. Male CC carriers were characterized by a possible increased risk of EAH: OR (95% CI) = 1.42 (0.56; 3.58). Moreover, the presence of the CC genotype in males could increase the risk of CAD: OR (95% CI) = 1.58 (0.63; 3.93).     

The ScaI gene polymorphism of the atrial natriuretic factor and essential arterial hypertension in childhood

In order to investigate the contribution of the atrial natriuretic factor (ANF) gene in pathogenesis of essential arterial hypertension (EAH), we analyzed the ScaI gene polymorphism of the ANF gene in a group of children with EAH. Fifty-eight children, aged 8-19 years, with the diagnosis of EAH were included in the association study and were compared to 57 subjects with normal blood pressure (the control group). Arterial hypertension was defined as systolic/diastolic blood pressure higher than the 95th age-gender-height percentile of the adopted reference values. We failed to demonstrate an association between the ScaI ANF gene polymorphism and EAH in childhood (OR = 2; 95% CI 0.9-4.2; p = 0.07), however, we provided evidence of an interaction between the ScaI ANF gene polymorphism and obesity defined as BMI over the 85th percentile (OR = 13.1; 95% CI 1.6-106; p < 0.001).     

Functional characterization of premnaspirodiene oxygenase, a cytochrome P450 catalyzing regio- and stereo-specific hydroxylations of diverse sesquiterpene substrates

Solavetivone, a potent antifungal phytoalexin, is derived from a vetispirane-type sesquiterpene, premnaspirodiene, by a putative regio- and stereo-specific hydroxylation, followed by a second oxidation to yield the alpha,beta-unsaturated ketone. Mechanistically, these reactions could occur via a single, multifunctional cytochrome P450 or some combination of cytochrome P450s and a dehydrogenase. We report here the characterization of a single cytochrome P450 enzyme, Hyoscyamus muticus premnaspirodiene oxygenase (HPO), that catalyzes these successive reactions at carbon 2 (C-2) of the spirane substrate. HPO also catalyzes the equivalent regio-specific (C-2) hydroxylation of several eremophilane-type (decalin ring system) sesquiterpenes, such as with 5-epi-aristolochene. Moreover, HPO displays interesting comparisons to other sesquiterpene hydroxylases. 5-Epi-aristolochene di-hydroxylase (EAH) differs catalytically from HPO by introducing hydroxyl groups first at C-1, then C-3 of 5-epi-aristolochene. HPO and EAH also differ from one another by 91-amino acid differences, with four of these differences mapping to putative substrate recognition regions 5 and 6. These four positions were mutagenized alone and in various combinations in both HPO and EAH and the mutant enzymes were characterized for changes in substrate selectivity, reaction product specificity, and kinetic properties. These mutations did not alter the regio- or stereo-specificity of either HPO or EAH, but specific combinations of the mutations did improve the catalytic efficiencies 10-15-fold. Molecular models and comparisons between HPO and EAH provide insights into the catalytic properties of these enzymes of specialized metabolism in plants.     

Impairment of TGF-beta signaling in T cells increases susceptibility to experimental autoimmune hepatitis in mice

In autoimmune hepatitis, strong TGF-beta1 expression is found in the inflamed liver. TGF-beta overexpression may be part of a regulatory immune response attempting to suppress autoreactive T cells. To test this hypothesis, we determined whether impairment of TGF-beta signaling in T cells leads to increased susceptibility to experimental autoimmune hepatitis (EAH). Transgenic mice of strain FVB/N were generated expressing a dominant-negative TGF-beta type II receptor in T cells under the control of the human CD2 promoter/locus control region. On induction of EAH, transgenic mice showed markedly increased portal and periportal leukocytic infiltrations with hepatocellular necroses compared with wild-type mice (median histological score = 1.8 +/- 0.26 vs. 0.75 +/- 0.09 in wild-type mice; P < 0.01). Increased IFN-gamma production (118 vs. 45 ng/ml) and less IL-4 production (341 vs. 1,256 pg/ml) by mononuclear cells isolated from transgenic livers was seen. Impairment of TGF-beta signaling in T cells therefore leads to increased susceptibility to EAH in mice. This suggests an important role for TGF-beta in immune homeostasis in the liver and may teleologically explain TGF-beta upregulation in response to T cell-mediated liver injury.     

Higher prevalence of exercise-associated hyponatremia in triple iron ultra-triathletes than reported for ironman triathletes

"In a recent study of male and female ultra-marathoners in a 161-km ultra-marathon, the prevalence of exercise-associated hyponatremia (EAH) was higher than reported for marathoners. Regarding triathletes, the prevalence of EAH has been investigated in Ironman triathletes, but not in Triple Iron ultra-triathletes. The aim of this study was to investigate the prevalence of EAH in male ultra-triathletes competing in a Triple Iron ultra-triathlon over 11.4 km swimming, 540 km cycling, and 126.6 km running. Changes in body mass, fat mass, skeletal muscle mass, total body water, haematocrit, plasma volume, plasma sodium concentration ([Na ? ]) and urine specific gravity were determined in 31 male athletes with (means ± standard deviation) 42.1 ± 8.1 years of age, 77.0 ± 7.0 kg body mass, 1.78 ± 0.06 m body height and a BMI of 24.3 ± 1.7 kg/m2 in the 'Triple Iron Triathlon Germany'. Of the 31 finishers, eight athletes (26%) developed asymptomatic EAH. Body mass, fat mass, skeletal muscle mass, and haematocrit decreased, plasma volume increased ( P < 0.05), plasma [Na ?], total body water and urine specific gravity remained stable. The decrease in body mass was related to both the decrease in fat mass and skeletal muscle mass ( P < 0.05), but was not related to overall race time, the change in plasma [Na ? ], post-race plasma [Na ? ], or urine specific gravity. The prevalence of EAH was higher in these Triple Iron ultra-triathletes compared to existing reports on Ironman triathletes. Body fluid homeostasis remained stable in these ultra-triathletes although body mass decreased."     

Maintained serum sodium in male ultra-marathoners--the role of fluid intake, vasopressin, and aldosterone in fluid and electrolyte regulation

Exercise-associated hyponatremia (EAH) is a well know electrolyte disorder in endurance athletes. Although fluid overload is the most like etiology, recent studies, however, argued whether EAH is a disorder of vasopressin secretion. The aims of the present study were to investigate (i) the prevalence of EAH in male ultra-marathoners and (ii) whether fluid intake, aldosterone or vasopressin, as measured by copeptin, were associated with post-race serum sodium concentration ([Na+]). In 50 male ultra-marathoners in a 100?km ultra-marathon, serum [Na+], aldosterone, copeptin, serum and urine osmolality, and body mass were measured pre- and post-race. Fluid intake, renal function parameters and urine excretion were measured. No athlete developed EAH. Copeptin and aldosterone increased; a significant correlation was found between the change in copeptin and the change in serum [Na+], no correlation was found between aldosterone and serum [Na+]. Serum [Na+] increased by 1.6%; body mass decreased by 1.9?kg. The change in serum [Na+] and body mass correlated significantly and negatively. The fluid intake of ~?0.58?l/h was positively related to the change in body mass and negatively to both post-race serum [Na+] and the change in serum [Na+]. We conclude that serum [Na+] was maintained by both the mechanisms of fluid intake and the hormonal regulation of vasopressin.     

Heritability of hyperphagic eating behavior and appetite-related hormones among Hispanic children

Objective: Eating in the absence of hunger (EAH) may be a genetically influenced phenotype of overweight children, but evidence is limited. This research evaluated the heritability (h²) of EAH and its association with overweight among Hispanic children 5 to 18 years old. Genetic and environmental associations of EAH with overweight, fat mass, and key hormonal regulators of food intake were also evaluated. Research Methods and Procedures: A family design was used to study 801 children from 300 Hispanic families. Weighed food intakes were used to measure EAH after an ad libitum dinner providing 50% of estimated energy needs. Fasting ghrelin, amylin, insulin, and leptin were measured by immunoassays. Measured heights, weights, and fat mass (using DXA) were obtained. Total energy expenditure (TEE) was measured by room respiration calorimetry. Results: On average, children consumed 41% of TEE at the dinner meal, followed by an additional 19% of TEE in the absence of hunger. Overweight children consumed 6.5% more energy at dinner (p < 0.001) and 14% more energy in the absence of hunger (p < 0.001) than non‐overweight children. Significant heritabilities were seen for EAH (h² = 0.51) and dinner intake (h² = 0.52) and for fasting levels of ghrelin (h² = 0.67), amylin (h² = 0.37), insulin (h² = 0.37), and leptin (h² = 0.34). Genetic correlations were seen between eating behavior and fasting hormones, suggesting common underlying genes affecting their expression. Discussion: This research provides new evidence that overweight Hispanic children exhibit elevated levels of hyperphagic eating behaviors that are influenced by genetic endowment.     

Residual plots for log odds ratio regression models.

This article describes graphical diagnostic methods for log odds ratio regression models. To study the effects of an additional covariate on log odds ratio regression analysis, three types of residual plots based on weighted least squares (WLS) are discussed: (i) added variable plot (partial regression plot), (ii) partial residual plot, and (iii) augmented partial residual plot. These plots provide diagnostic procedures for identifying heterogeneity of error variances, outliers, or nonlinearity of the model. They are especially useful for clarifying whether including a covariate as a linear term is appropriate, or whether quadratic or other nonlinear transformations are preferable. A well-known data set for case-control studies is analyzed to illustrate the residual plots.     

Association of T3111C polymorphism in 3′-untranslated region of the <Emphasis Type="Italic">Clock</Emphasis> gene with the risk of essential arterial hypertension and coronary artery disease in the Russian population (Residents of Karelia)

Allele and genotype distributions of the T3111C polymorphism in 3′-untranslated region of the Clock gene were examined in the groups of Russian patients with essential arterial hypertension (EAH) and coronary artery disease (CAD), and in control group of Russia residents of the Republic of Karelia. The genotype frequency distributions of the polymorphism examined in the EAH and CAD patients were statistically significantly different from that in the individuals without clinical signs of these diseases. The CC genotype frequency in EAH and CAD males was higher, and in the corresponding females it was lower than in males and females from the control group. Male CC carriers were characterized by a possible increased risk of EAH: OR (95% CI) = 1.42 (0.56; 3.58). Moreover, the presence of the CC genotype in males could increase the risk of CAD: OR (95% CI) = 1.58 (0.63; 3.93).     

PEDPLO: a pedigree plot program

The program PEDPLO supports the graphical presentation of inheritance. The plot produced is a tree ramifying towards the younger generation. There is only little dependence on the special software and hardware of the plot.     

No case of exercise-associated hyponatremia in male ultra-endurance mountain bikers in the 'Swiss Bike Masters'

Exercise-associated hyponatremia (EAH) has mainly been investigated in runners and triathletes. In mountain bikers, EAH was studied in two multi-stage races, but not in a single stage race. The aim of this study was to investigate the prevalence of EAH in a single-stage mountain bike ultra-marathon. In the 'Swiss Bike Masters' over 120 km with a climb of ~ 5,000 m in altitude, we determined pre and post race body mass, hematocrit, plasma sodium concentration ([Na?]), and urinary specific gravity in 37 cyclists. Athletes recorded their fluid intake while racing. No athlete developed EAH. The cyclists drank on average (means ± SD) 0.7 ± 0.2 l/h. Fluid intake was significantly and negatively related to race time (r = -0.41, P < 0.05), but showed no association with post race plasma [Na?], the change in plasma [Na?], post race body mass, or the change in body mass. The athletes lost 1.4 kg body mass (P < 0.05), plasma [Na?] decreased by 0.7% (P < 0.05), plasma volume increased by 1.4% and urinary specific gravity increased by 0.4% (P < 0.05). The change in body mass was neither related to post race plasma [Na?] nor to the change in plasma [Na?]. The decrease in plasma [Na?] was not related to fluid intake. The change in plasma [Na?] was related to post race plasma [Na?] (r = 0.40, P < 0.01). Ad libitum fluid intake showed no case of EAH in a single-stage mountain bike ultra-marathon. In contrast to previous findings, the faster athletes drank more than the slower ones.     

Cellular aspects of pathogenesis of hypertrophic cardiomyopathy: Role of cardiomyocyte polyploidy and activation of nuclear antigen of the proliferating cell in myocardium

For a comparative analysis of cytomorphological characteristics of hypertrophied interventricular septum (IVS), both patients different ages with severe courses of obstructive hypertrophic cardiomyopathy (OHCMP) were examined, including children, and patients with essential arterial hypertension (EAH). The course of OHCMP in children as compared with adults was found to be characterized by considerable IVS hypertrophy that was accompanied by an acceleration of cardiomyocyte polyploidization. The mean ploidy level of cardiomyocytes in children with OHCMP was higher than in adult patients. The mean ploidy level of nuclei, the number of prolipherative cell nuclear antigen (PCNA)-positive nuclei, and the number of polyploid cardiomyocyte nuclei in adult patients with OHCMP were significantly higher statistically than in patients with EAH. The PCNA-positive labels in stromal cells were revealed only in patients with OHCMP. The obtained data indicate an important role of cardiomyocyte polyploidy and of activation of the proliferating cell nuclear antigen in development of myocardial hypertrophy in patients with OHCMP.     

Determination of the association constants and maximum binding capacities between estradiol and cytosol of the uterus by the least-squares analysis of the Scatchard plot.

The association constants and the binding capacities of association of small molecules with macromolecules have been determined by the tangent analysis, the graphical analysis, and the computer data analysis, by trial and convergence of the Scatchard plot. The analytical method for the calculation of the binding parameters based on the Scatchard plot was derived and the optimum values of the binding parameters were obtained by the least squares calculation based on the analytical method. The errors by the analytical method were smaller than those by the graphical method in the equilibrium system between 3H-estradiol and some cytosols of uterus.     

Graphic presentation and analysis of inhibition data from ligand-binding experiments

One technique for the characterization of receptor subtypes involves measuring the inhibition of the binding of a radioligand which is not subtype selective by agonists or antagonists which are subtype selective. Although such data are routinely calculated using computer programs, it is often useful to have a graphical representation of the data. Until now, a "modified Scatchard" or "Hofstee" plot of the form P = -(P/I)(IC50) + 1 (where P is percentage inhibition and I is the inhibitor concentration) has been used. We describe an alternate plot of the form B = -(B X I)(1/IC50) + B0 (where B is the concentration of bound radioligand and B0 is the concentration of radioligand bound in the absence of the inhibitor). This method has the important advantage that the data need not be calculated as percentage inhibition which eliminates the error involved in the experimentally determined B0 value being included in the other values.     

Theoretical considerations of the Tsou plot

A graphical method was proposed by Tsou in 1962 for interpreting the data obtained by chemical modification of proteins and determining the number of essential groups involved. A strict mathematical proof and the estimation of deviation probability for this method are presented here. From the well-known Chebyshev's inequality, it has been shown that the possible error which could be derived from the Tsou plot will be much smaller than the usual experimental error obtainable. Some problems related to experiment and to application of Tsou plot in oligomeric enzymes have been discussed. Some analysis of experimental data taken from the literature are presented.     

Analysis of RNA-DNA competition hybridization using the Scatchard plot

The Scatchard plot is convenient for expressing RNA-DNA competition hybridization data because the maximum amount of competition is directly read as the X-intercept. The derivation which validates the use of this graphical method for competition hybridization data is presented.