Biomedical subjects

Carlos E Fardella

Publications and source records attributed to Carlos E Fardella.

8 recordsLinked to original sources

PubMed2006

[Microsatellite marker AGAT of the mineralocorticoid receptor gene is associated with plasma renin activity in patients with essential hypertension].

BACKGROUND: Hypertensive states could result from constitutive activation of mineralorticoid receptor (MR) that generates salt retention and blood pressure elevation. Moreover, microsatellite regions can be associated to the regulation of the gene expression, producing subtle pathologies. AIM: To determine the influence of microsatellite marker AGAT of the mineralocorticoid receptor gene in the plasma renin activity (PRA) and serum aldosterone (SA) levels of essential hypertensives (HT). PATIENTS AND METHODS: We studied 292 HT patients and 57 normotensive (NT) controls. Blood samples were collected for PRA, SA and DNA isolation. Subjects were genotyped according to the length of the tetranucleotide AGAT repeat using polymerase chain reaction and polyacrylamide gel electrophoresis. Based on the normal distribution, we considered 13 to 15 repeats as a habitual (H) length and less than 13 or more than 15 repeats, as non-habitual (non-H). RESULTS: We detected 8 different lengths in the AGAT repeat (allele) in both groups, ranging from 9-17 repeats, where the allele 11 was not detected in either hypertensive or normotensive groups. The allelic distribution was different in both groups (c2 =37.57, 4GL, p <0.001). In hypertensive patients, the H group showed higher PRA levels (median (Q1-Q3)) than the non-H group: 1.3 (0-7-3.5) vs 1.0 (0.5-2.3) ng/mL*h, p <0.05. The SA levels did not show differences between both groups, but the SA*PRA product was higher in the H group than the no-H group: 9.3 (3.0-24.6) vs 6.5 (2.5-14.6) p <0.05. In normotensive patients, no differences were observed in PRA, SA and SA*PRA between both groups. CONCLUSION: These results show association between the length of the AGAT repeat with the PRA in HT, suggesting a plausible role in the control of the MR gene expression, and secondarily in the regulation of blood pressure.

Aldosterone↗

PubMed2005

Biochemical and genetic characterization of 11 beta-hydroxysteroid dehydrogenase type 2 in low-renin essential hypertensives.

BACKGROUND: The 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2) catalyzes the conversion of cortisol (F) to cortisone (E), avoiding the interaction of cortisol with the mineralocorticoid receptor. If it fails, cortisol will stimulate sodium and water reabsorption, increasing the intravascular volume that suppresses renin and secondarily increase the blood pressure. OBJECTIVE: To look for the possible contribution of a decreased ability of 11betaHSD2 to convert cortisol to its inactive metabolite cortisone in the pathogenesis of low renin hypertension (LREH). PATIENTS AND METHODS: We studied 64 LREH patients (plasma renin activity, PRA < 1 ng/ml per h), eighty normo-renin essential hypertensives (NREH) (PRA: 1-2.5 ng/ml per h) and 74 normotensives. Serum aldosterone (SA), F, E and serum F/E ratio was determined in all patients. A serum F/E ratio was considered high when it was higher than X + 2SD from the normotensive value. Cytosine-adenine (CA)-repeat microsatellite region in intron 1 of HSD11B2 gene was genotyped in all patients and normotensives volunteers. In 13 LREH with high F/E ratio we performed HSD11B2 gene sequencing. RESULTS: LREH had serum F/E ratio higher than NREH and normotensive controls (3.6 (2.9-4.3) versus 2.9 (2.2-4.3) versus 3.0 (2.4-3.7) (P = 0.004), respectively). We observed an inverse relation between F/E ratio and SA and PRA. In NREH and normotensives we did not find correlation between these variables. In the LREH subset the longer 155 bp CA-allele showed the highest serum F/E ratio. No mutations in coding region or short introns were found in LREH patients. CONCLUSION: In this study we show that low-renin essential hypertensives had increased serum cortisol/cortisone ratios as compared with normotensive subjects. This suggest that some essential hypertensives, with suppressed renin activity, may have an impairment in the cortisol inactivation catalyzed by the enzyme 11betaHSD2, whose low activity in LREH patients could be associated with the length of CA-repeat microsatellite in intron 1 of the HSD11B2 gene.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗

PubMed2004

Congenital lipoid adrenal hyperplasia caused by a novel splicing mutation in the gene for the steroidogenic acute regulatory protein.

Steroidogenic acute regulatory protein (StAR) plays a crucial role in the transport of cholesterol from the cytoplasm to the inner mitochondrial membrane, facilitating its conversion to pregnenolone by cytochrome P450scc. Its essential role in steroidogenesis was demonstrated after observing that StAR gene mutations gave rise to a potentially lethal disease named congenital lipoid adrenal hyperplasia, in which virtually no steroids are produced. We report here a 2-month-old female patient, karyotype 46XY, who presented with growth failure, convulsions, dehydration, hypoglycemia, hyponatremia, hypotension, and severe hyperpigmentation suggestive of adrenal insufficiency. Serum cortisol, 17OH-progesterone, dehydroepiandrosterone sulfate, testosterone, 17OH-pregnenolone, and aldosterone levels were undetectable in the presence of high ACTH and plasma renin activity levels. Immunohistochemical analysis of testis tissues revealed the absence of StAR protein. Molecular analysis of StAR gene demonstrated a homozygous G to T mutation within the splice donor site of exon 1 (IVS1 + 1G>T). Her parents and one brother were heterozygous for this mutation. In vitro analysis of the mutation was performed in COS cells transfected with minigenes coding regions spanning exon-intron 1 to 3 carrying the mutant and the wild-type sequences. RT-PCR analyses of the mutant gene showed an abnormal mRNA transcript of 2430 bp (normal size 433 bp). Sequence analysis of the mutant mRNA demonstrated the retention of intron 1. Immunolocalization of the StAR minigene product detected the peptide in the mitochondria of COS cells transfected with the wild-type minigene but not in those transfected with the mutant minigene. We conclude that this mutation gives rise to a truncated StAR protein, which lacks an important N-terminal region and the entire lipid transfer domain.

Adrenal Hyperplasia, Congenital↗

PubMed2004

Increased diagnosis of primary aldosteronism, including surgically correctable forms, in centers from five continents.

Primary aldosteronism (PA) is a common form of endocrine hypertension previously believed to account for less than 1% of hypertensive patients. Hypokalemia was considered a prerequisite for pursuing diagnostic tests for PA. Recent studies applying the plasma aldosterone/plasma renin activity ratio (ARR) as a screening test have reported a higher prevalence. This study is a retrospective evaluation of the diagnosis of PA from clinical centers in five continents before and after the widespread use of the ARR as a screening test. The application of this strategy to a greater number of hypertensives led to a 5- to 15-fold increase in the identification of patients affected by PA. Only a small proportion of patients (between 9 and 37%) were hypokalemic. The annual detection rate of aldosterone-producing adenoma (APA) increased in all centers (by 1.3-6.3 times) after the wide application of ARR. Aldosterone-producing adenomas constituted a much higher proportion of patients with PA in the four centers that employed adrenal venous sampling (28-50%) than in the center that did not (9%). In conclusion, the wide use of the ARR as a screening test in hypertensive patients led to a marked increase in the detection rate of PA.

Aldosterone↗

PubMed2004

Novel intronic mutation of MEN1 gene causing familial isolated primary hyperparathyroidism.

Primary hyperparathyroidism may occur as part of hereditary syndromes, including multiple endocrine neoplasia types 1 and 2A (MEN1 and MEN2A), hyperparathyroidism-jaw tumor syndrome, and the familial isolated hyperparathyroidism (FIHP). It is unclear whether FIHP corresponds to a different genetic entity or a variant of MEN1 (or hyperparathyroidism-jaw tumor syndrome). We report a patient and 11 family members with FIHP in whom we identified a heterozygous G-to-A mutation at nucleotide 7361 of tumor suppressor MEN1 gene. This mutation is located in the first base of intron 9 (IVS9 + 1 G>A). All the family members with hyperparathyroidism were heterozygous for the intronic mutation. In vitro studies were performed in COS cells transfected with minigenes carrying the coding regions spanning exon-intron 9 and 10 with the mutant and the wild-type sequences. RT-PCR analyses showed an abnormal mRNA of greater size (829 bp) in the mutated MEN1 gene than the normal transcript (629 bp). The longer PCR product includes the exon 9, the unspliced intron 9, and part of exon 10. RT-PCR of MEN1 mRNA from patient's blood confirmed the existence of unspliced intron 9 in mature mRNA. In summary, we report a case of FIHP associated with a new intronic heterozygous germline mutation (IVS9 + 1 G>A) of MEN1 gene. This mutation produces an aberrant splicing of mRNA that could lead to a truncated protein, without activity, explaining the clinical picture of this patient and his family.

Adenine↗

PubMed2003

Primary aldosteronism and hypertensive disease.

Recent studies in hypertensive populations that have used the serum aldosterone (SA) to plasma renin activity (PRA) ratio as a screening test have demonstrated a high prevalence of primary aldosteronism (PA). This frequency is higher than that previously described when hypokalemia was used as a screening tool. However, other factors, such as the characteristics of hypertensive disease, could also influence the prevalence of PA. We studied 609 essential hypertensive patients, classified according to the Joint National Committee VI (JNC VI), in 3 different stages depending on the severity of their hypertensive disease. We measured SA and PRA and calculated the SA-PRA ratio for all patients. An SA-PRA ratio >25 was detected in 63 of 609 patients, and the fludrocortisone test confirmed the PA diagnoses in 37 of 609 (6.1%) cases. PA prevalence according to hypertension stage was as follows: stage 1, 6 of 301 cases (1.99%); stage 2, 15 of 187 cases (8.02%); and stage 3, 16 of 121 cases (13.2%). PA patients were slightly younger than the other hypertensive patients (48.4+/-10.5 vs 53.6+/-10.2 years; P<0.05). Serum potassium levels were normal in 36 of 37 PA patients; only 1 patient had minor hypokalemia. Computed tomography scans showed bilateral adrenal enlargement in 7 and an adrenal nodule in 2 cases. In summary, we found a high frequency of PA in essential hypertensives classified in stages 2 and 3 according to the JNC VI. The low frequency of computed tomography scan abnormalities and hypokalemia suggests that the diagnosis for most PA patients corresponds to attenuated forms of the disease.

Aldosterone↗

PubMed2003

Two homozygous mutations in the 11 beta-hydroxysteroid dehydrogenase type 2 gene in a case of apparent mineralocorticoid excess.

The human microsomal 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta HSD2) metabolizes active cortisol into cortisone and protects the mineralocorticoid receptor from glucocorticoid occupancy. In a congenital deficiency of 11 beta-HSD2, the protective mechanism fails and cortisol gains inappropriate access to mineralocorticoid receptor, resulting in low-renin hypertension and hypokalemia. In the present study, we describe the clinical and molecular genetic characterization of a patient with a new mutation in the HSD11B2 gene. This is a 4-yr-old male with arterial hypertension. The plasma renin activity and serum aldosterone were undetectable in the presence of a high cortisol to cortisone ratio. PCR amplification and sequence analysis of HSD11B2 gene showed the homozygous mutation in exon 4 Asp223Asn (GAC-->AAC) and a single nucleotide substitution C-->T in intron 3. Using site-directed mutagenesis, we generated a mutant 11 beta HSD2 cDNA containing the Asp223Asn mutation. Wild-type and mutant cDNA was transfected into Chinese hamster ovary cells and enzymatic activities were measured using radiolabeled cortisol and thin-layer chromatography. The mRNA and 11 beta HSD2 protein were detected by RT-PCR and Western blot, respectively. Wild-type and mutant 11 beta HSD2 protein was expressed in Chinese hamster ovary cells, but the mutant enzyme had only 6% of wild-type activity. In silico 3D modeling showed that Asp223Asn changed the enzyme's surface electrostatic potential affecting the cofactor and substrate enzyme-binding capacity. The single substitution C-->T in intron 3 (IVS3 + 14 C-->T) have been previously reported that alters the normal splicing of pre-mRNA, given a nonfunctional protein. These findings may determine the full inactivation of this enzyme, explaining the biochemical profile and the early onset of hypertension seen in this patient.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗

PubMed2002

Primary aldosteronism.

Primary aldosteronism is a potentially curable form of hypertension. Recent studies using the plasma aldosterone to plasma renin activity ratio as screening test in hypertensive populations have demonstrated a high prevalence of primary aldosteronism close to 10%. This frequency is clearly higher than the classically described when hypokalemia is used as the screening method. The most common subtypes of primary aldosteronism are idiopathic aldosteronism and aldosterone-producing adenoma. Other causes are glucocorticoid-remediable aldosteronism, unilateral or primary adrenal hyperplasia and adrenal carcinoma. The diagnosis of primary aldosteronism is advocated to confirm the autonomy of aldosterone secretion from the renin-angiotensin system and to differentiate the clinical subtypes of the disease. This article reviews the new data about prevalence, diagnosis criteria and describes the clinical, biochemical and genetic characteristics of the different subtypes of the disease. We also discuss the treatment, and the differential diagnosis with other hyper-mineralocorticoid states.

Aldosterone↗