Biomedical subjects

O Monte

Publications and source records attributed to O Monte.

6 recordsLinked to original sources

PubMed2004

Inhibin alpha-subunit (INHA) gene and locus changes in paediatric adrenocortical tumours from TP53 R337H mutation heterozygote carriers.

The R337H TP53 mutation is a low-penetrance molecular defect that predisposes to adrenocortical tumour (ACT) formation in Brazilian and possibly other populations. Additional genetic defects may be responsible for the variable expression of ACTs in these cases. The inhibin alpha-subunit gene (INHA) on 2q33-qter has been implicated in mouse adrenocortical tumourigenesis. We studied 46 pediatric patients with ACTs from Brazil for INHA genetic alterations; 39 of these patients were heterozygous carriers of the R337H TP53 mutation. We first mapped the INHA gene by radiation hybrid analysis and determined 10 linked microsatellite markers in an area flanked by D2S1371 and D2S206 on 2q33-qter. These markers were then used for loss of heterozygozity (LOH) studies in nine paired germline and tumour DNA samples. Mapping placed the INHA gene in close proximity to D2S2848 (SHGC11864) with a log of odds (LOD) score of 5.84. LOH for at least one marker in the region was identified in 8/9 tumours (89%). Six patients were heterozygous for three INHA mutations: one in exon 1, 127C>G, and two in exon 2, 3998G>A and 4088G>A, all leading to amino acid substitutions (P43A, G227R, and A257T, respectively). A257T is located in a conserved INHA region, highly homologous to transforming growth factor-beta; both G227R and A257T change polarity, and, in addition, G227R changes the pH. We conclude that these sequence alterations and the detected 2q allelic changes suggest that INHA may be one of the contributing factors needed for ACT formation in pediatric patient carriers of the R337H TP53 mutation.

Adrenal Cortex Neoplasms↗

PubMed2000

Low glucocorticoid receptor alpha/beta ratio in T-cell lymphoblastic leukemia.

Glucocorticoid therapy is pivotal in the treatment of acute lymphoblastic leukemia (ALL); it reduces cell proliferation, promotes cell cycle arrest, and induces cell death by apoptosis. The sensitivity of leukemic cells to glucocorticoids was previously related to the cell concentration of 3[H]dexamethasone-binding sites. The latter represents the classic glucocorticoid receptor (GR) isoform alpha that binds ligand and modulates the transcription rates of glucocorticoid-responsive genes. In ALL, lymphoblasts of T-lineage are less sensitive to glucocorticoids than cells of the B-lineage. The alternatively spliced GR isoform (GRP), which exerts a dominant negative effect on GRalpha-mediated transcriptional activity, has been proposed as a possible mediator of glucocorticoid resistance. In this study, we determined the amount of GRalpha and GRbeta in mononuclear cells from 13 newly diagnosed and untreated children with ALL and 9 controls by quantitative Western analysis. Generally, leukemic patients expressed 6 times less GRalpha (ALL= 0.54 +/- 1.1; controls = 3.1 +/- 0.9; p < 0.01) than controls, but the same amount of GRbeta (ALL=3.62 +/- 3.3; controls = 3.6 +/- 3.4). ALL patients with T-cell disease had a much lower GRalpha (0.09 +/- 0.1; p < 0.01) but a similar or slightly higher GRbeta (5.98 +/- 3.9; p = 0.1) expression than controls, with a GRalpha/GRbeta ratio 15 times smaller than controls. Mononuclear leukocytes of T-cell lineage expressed significantly lower GRalpha (p = 0.04) and higher GRbeta (p < 0.01) than cells of the pre-B immunophenotype, with a 10 times smaller ratio. We conclude that the combination of low GRalpha and normal-to-high GRbeta expression in leukemic lymphoblasts might represent one of the mechanisms responsible for their reduced glucocorticoid sensitivity; this is more pronounced in T-lineage cells.

Adolescent↗

PubMed1999

A novel missense mutation, GLY424SER, in Brazilian patients with 21-hydroxylase deficiency.

A previous screening of 17 mutations in 130 Brazilian patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency did not identify mutations in 20% of the alleles. To diagnose these alleles we sequenced the entire CYP21 gene of one Mulatto patient with the simple virilizing form, who had only the R356W mutation in a heterozygous state. We identified a heterozygous G-A transition in codon 424. This mutation leads to a substitution of glycine by serine in a conserved region where glycine is conserved in at least 4 species. This novel mutation eliminates 1 of the restriction sites of the BanI enzyme, which made its screening possible for the whole series. The G424S mutation was found in a compound heterozygous state in 5 families; 4 presented the simple virilizing form, and 1 presented the nonclassical form. Interestingly, 3 of 5 families have a Mulatto origin. This mutation was not identified in 118 CYP21 alleles of normal individuals, ruling out the possibility of a polymorphism, or in 80 pseudogenes, indicating a casual mutagenic event and not a microconversion event. All patients with the G424S mutation presented CYP21P and C4A gene deletions and human leukocyte antigen DR17 on the same haplotype, suggesting a linkage disequilibrium and a probable founder effect. Search for the G424S mutation in other populations will reveal whether it is restricted to the Brazilian patients or if it has a wider ethnic distribution.

Adrenal Hyperplasia, Congenital↗

PubMedDate not supplied

Adrenal steroids synthesis during acute infectious diseases in infants.

UNLABELLED: An increase in plasma 17OHP found in infants requiring differential diagnosis between septic shock and adrenal failure led us to look for adrenal steroids pattern during infection. INFANTS AND METHODS: 56 infants, 1-6 months old, were studied during infection of different degrees of severity. Plasma cortisol, 17OHP, androstenedione, DHEA, DHEA-S and testosterone were measured. RESULTS: 24 patients showed an expected cortisol elevation. One child had a low cortisol level. The concentration of 17OHP was above 6.0 nmol/l (200 ng/dl) in 41 patients and above 30.2 nmol/l (1,000 ng/dl) in 10. Higher 17OHP levels and more severe diseases correlated positively. CONCLUSIONS: During infectious diseases some patients demonstrated not only cortisol elevation but also 17OHP as high as that observed in NC-CAH. We suggest that if 17OHP elevation is not characteristic of SL-CAH, glucocorticoid therapy should be started and an ACTH test should be performed after recovery before ruling out this pathology.

17-alpha-Hydroxyprogesterone↗

PubMedDate not supplied

Detection of codon 12 mutation in the K-ras oncogene in pancreatic tumors.

Mutations at codons 12, 13, or 61 of the H-ras, K-ras, and N-ras have been detected in human neoplasias by a variety of techniques. Some of these techniques are very sensitive and can detect K-ras mutation in 90% of the cases of pancreatic adenocarcinomas. We analyzed 11 samples of pancreatic adenocarcinoma, three samples of pancreatic mucinous cystadenoma, and two samples without tumors in formalin-fixed paraffin embedded tissue sections. K-ras mutations at codon 12 were detected by a two-step PCR-enriched technique in all the samples of pancreatic adenocarcinoma, but not in cystadenoma or control samples. This technique may be useful for early detection of pancreatic cancer.

Codon↗

PubMedDate not supplied

[Cryptorchism: basic concepts and hormonal therapy].

The authors analyze the clinical results of 368 cryptorchid testis that received intramuscular human chorionic gonadotropin (HCG), at the dose of 50 U/kg once a week for 6 weeks. The patients with inguinal anatomical abnormalities or only with subtle retractility were excluded. There was a correlation among the testicle position, the cryptorchism side, the patient's age at the time of the therapy and the results obtained. We observed (i) a delay on child referral; (ii) concurrence of cryptorchism and systemic diseases, most of them with genetical origin; (iii) better results was obtained in children with retractile testis, older than 4 years old and with bilateral cryptorchism. The efficacy of second hormonal treatment was only present in retractile testis that showed partial response to the first hormonal therapy. It is argued that, although the treatment of children under 2 is less effective, the possible prevention of testicular lesions for this early intervention justify the hormonal therapy between 6 and 9 months of life.

English Abstract↗