In small metazoan invertebrates classical taxonomic analyses can be ambiguous due to the limited number of morphological characters available. This difficulty can yield incorrect estimates of species ...richness or taxa distribution. The Boeckella genus has been described as the dominant taxon of zooplankton assemblages in the Andean biogeographical region. In this genus, taxonomic classification and delimitation of boundaries between species has long been problematic and controversial. Among South American centropagids Boeckella gracilipes has been regarded as one of the most broadly distributed species, its presence having been reported from Ecuador to Tierra del Fuego. However, in the high Andean plateau some centropagid populations identified as Boeckella gracilipes have also been considered as B. gracilipes titicacae or even identified as a different species, namely Boeckella titicacae. In an attempt to resolve the taxonomic status of the Centropagidae family from the high Andean plateau, we combined traditional and multivariate morphological analyses (integral approach) with the molecular phylogenetic approach. The results obtained allow us to conclude that centropagids collected from the high Andean plateau actually represent a different species, B. titicacae, not B. gracilipes. The phylogenetic reconstruction of the South American Centropagidae family indicated that B. gracilipes represents a sister taxon to B. titicacae. The present study stresses the usefulness of integrating alfa-taxonomy with morphometric and molecular approaches in order to resolve species boundaries, to determine geographical distributions and to investigate evolutionary processes.
Increasing evidence suggests that glucocorticoids might play a role in blood pressure (BP) control. These reports show that cortisol (F) can increase the BP acting on the mineralocorticoid receptor ...in kidney, brain, heart, and blood vessel. The aim of this study was to evaluate the effects of F in the renal salt and water reabsorption in essential hypertensive patients (EH).
We studied 364 EH and 102 normotensive (NT) subjects. We obtained 24-h urine to measure urinary free cortisol (UFF) and creatinine (Cr). The upper limit of the UFF/Cr ratio was calculated from NT subjects. Patients with a high UFF/Cr ratio underwent dexamethasone suppression test (DST). Blood samples were used to determine plasma renin activity (PRA), aldosterone (SA), F, cortisone (E), urinary Na/K ratios, adrenocorticotrophic hormone levels, and also to purify lymphocytes for binding assays and genetic analysis.
In EH subjects the UFF/Cr and F/E ratios were higher than in normotensives (48.3 μg/g 33.6 to 57.5 μg/g
v 32.6 μg/g 5.6 to 34.6 μg/g,
P < .001 and 3.9 μg/g 3.3 to 4.8 μg/g
v 3.0 μg/g 2.4 to 3.6 μg/g, respectively), whereas the SA and PRA levels were similar. The upper limit value for UFF/Cr was set at 51.6 μg/g. The EH patients with high UFF/Cr (123/364, 34%) had lower PRA (1.5 ng/mL/h 0.9 to 2.5 ng/mL/h
v 2.0 ng/mL/h 1.1 to 3.0 ng/mL/h,
P = .012, SA levels (7.1 ng/dL 4.1 to 10.5 ng/dL
v 7.9 ng/dL 5.2 to 11.0 ng/dL,
P = .045
) and Na/K ratios (3.6 2.8 to 5.8
v 4.0 3.1 to 6.6,
P ≤ .05) than those with normal UFF/Cr ratios. We found a slight negative relationship between UFF/Cr and PRA (
r = −0.117,
P = .031), SA (
r = −0.096,
P = .058) and Na/K ratios (
r = 0.176,
P = .059). We did not find significant differences in serum F/E ratios between EH patients with high or normal UFF/Cr (3.9 3.3 to 5.1
v 3.8 3.2 to 4.7,
P = not significant NS) or a correlation between F/E ratio and UFF excretion (
r = 0.032,
P = NS). We did not find any association between UFF/Cr with systolic BP (
P = .349) or diastolic BP (
P = .895). Forty EH with the highest UFF/Cr values underwent the DST, which resulted in suppressed serum F in all of them. Binding assays in 4 of 13 EH with the highest UFF/Cr ratio showed a low affinity to dexamethasone (K
d 13.7 to 33.0 nmol/L). The polymerase chain reaction (PCR) amplification of the GR gene (ligand-binding domain exons) did not show mutations or gross alterations.
We found an EH subpopulation with abnormally high values of UFF but evidence of only a minor mineralocorticoid action, which was not directly related to the BP elevation, suggesting that another alternative mechanism could be triggering the F-induced hypertension. The origin of hypercortisoluria was not elucidated; however, a subtle glucocorticoid resistance was found in some cases.
The epithelial sodium channel (ENaC) is a candidate gene associated with the development of essential hypertension. A potentially polymorphic repetitive region (GT dinucleotide short tandem repeat ...STR) was identified in intron 8 of beta-ENaC gene (SCNN1B). The aim of this study was to identify the prevalence and distribution of a polymorphic GT-STR in SCNN1B in Chilean essential hypertensive (EH) patients and to analyze the correlation between the different genotypes with plasma renin activity (PRA) and serum aldosterone (SA), and furthermore, to evaluate the beta-ENaC gene expression in vitro. We studied 133 patients with EH and 69 normotensive (NT). In both EH and NT subjects we measured PRA, SA, urine sodium, and genotyped them according to the GT-STR length using sequencing analysis. We detected 11, 13 and 14 GT alleles in EH and NT subjects. Both groups were classified according to genotype: 14/14, 14/13, 13/13, 13/11, and 11/11. Influence of the GT-STR on beta-ENaC minigene expression was evaluated by real-time polymerase chain reaction. In EH, PRA decreased with the length of the STR region 11/13, 1.40 +/- 0.69; 13/13, 1.16 +/- 0.61; 13/14, 0.90 +/- 0.56; 14/14, 0.32 +/- 0.09 ng/mL/h; P < .01. Likewise, PRA in patients with EH with 14/14 or 14/13 genotypes were lower than EH with 13/13 or 13/11 genotypes (0.77 +/- 0.5 v 1.24 +/- 0.6 ng/mL/h; P < .01). Real-time polymerase chain reaction demonstrated an increased beta-ENaC expression in minigenes containing 14 GT-STR. We have identified a polymorphic GT-STR in the beta-ENaC gene, which is present in the EH and NT Chilean population. Biochemical analysis showed a possible linkage between this polymorphic region and low renin hypertension. The in vitro assay suggests that GT-STR could regulate the beta-ENaC expression.
Glucocorticoids play a key role in blood pressure (BP) control and are associated with hypertension in patients with Cushing's syndrome. A number of reports indicate that cortisol (F) may be involved ...in etiology of essential hypertension (EH). F can bind to the mineralocorticoid receptor, triggering both sodium and water reabsorption in kidney, increase BP and cause renin suppression.
To evaluate urinary free cortisol (UFF) excretion as a potential intermediate phenotype of essential hypertension and correlate F level with plasma renin activity (PRA) and serum aldosterone (SA).
We recruited 132 EH patients and 16 normotensive healthy controls. Blood samples and 24 hours urine were collected for PRA, SA and UFF analysis. Differences in UFF excretion between sexes were normalized by urinary creatinine (Creat) excretion. The upper limit of UFF/Creat was determined in normotensives considering the mean value plus 2 standard deviations. According to this value, subjects were classified as having high or normal UFF.
In EH patients and in normotensives, the UFF/Creat was 36.9 +/- 17.0 microg/gr and 30.9 +/- 8.8 microg/gr, respectively. The upper limit was set at 48.5 microg/gr. A high UFF/Creat was found in 20/132 EH (15%) patients and 0/16 normotensive subjects. EH patients with high UFF showed lower PRA levels than patients with normal cortisol levels (0.78 +/- 0.47 vs. 1.13 +/- 0.66 ng/ml x h, respectively, p=0.027) and lower SA values (4.52 +/- 1.65 vs 6.34 +/- 3.37 ng/dl, respectively, p=0.018). There was a negative correlation between UFF and PRA (r=-0.176, p=0.044) and between UFF and SA (r=-0.183, p=0.036).
We have identified a subgroup of EH patients with increased UFF excretion. Patients with the highest UFF showed lower renin and aldosterone levels. These data suggest a potential influence of cortisol in the genesis of hypertension.
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