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Biomedical subjects

E Salido

Publications and source records attributed to E Salido.

At least 19 recordsLinked to original sources
PubMed1999

Mouse p73 gene maps to the distal part of chromosome 4 and might be involved in the progression of gamma-radiation-induced T-cell lymphomas.

We have isolated and sequenced a DNA fragment of about 12 kb that comprises exons 5-14 of the mouse p73 gene. We have identified four polymorphic markers, and one of them has been used to genetically map p73 to the distal part of chromosome 4. Previously, we have reported that gamma-radiation-induced T-cell lymphomas undergo frequent loss of heterozygosity around marker D4Mit205b at the distal part of chromosome 4. Based on this, we have performed loss of heterozygosity analysis in a set of T-cell lymphomas, and we have found allelic losses of p73 in 32.6% (16 of 49) of the tumors analyzed. Interestingly, allelic losses occur concurrently at both p73 and D4Mit205b, thus suggesting that p73 could be specifically inactivated in radiation-induced T-cell lymphomas.

Alleles↗
PubMed1998

[Genetic polymorphism of vitamin D receptor and osteoporosis].

BACKGROUND: Genetic factors condition an important part of bone mass. The role of vitamin D receptor polymorphism (VDR) as genetic marker of osteoporosis is a matter of discussion. We have studied the possible influence of VDR on bone remodelling, calciotropic hormones, on the presence of osteoporosis and osteoporotic bone fractures. PATIENTS, CONTROL POPULATION AND METHODS: A case-control study. We have studied a total of 127 postmenopausal Canarian women from Canary Islands, Spain; 66 healthy controls and 61 with the diagnosis of osteoporosis, which was made by clinical, radiological and densitometric criteria. 17 osteoporotic women have had a fracture: Colles, hip or vertebral (spinal deformity index) fracture. VDR were determined by PCR directed to demonstrate the presence (b) or absence (B) of a restriction target for Bsml in intron 7. We analyzed some biochemical markers of bone remodelling: serum levels of alkaline phosphatase, tartrate resistant acid phosphatase and urine ratios of calcium/creatinine and hydroxyproline/creatinine. We also determined calciotropic hormones: parathyroid hormone and calcitonin. Bone mass was measured by DEXA and TC. RESULTS: There were no significant differences in either biochemical bone remodelling markers or in bone mass between the three genotypes: bb, Bb and BB, either in controls or in osteoporotic women with the exception of alkaline phosphatase which had a significative increase compared to control in women with unfavorable alleles distribution (bB and BB). Distribution of genotypes was similar between controls and osteoporotic women, with or without fractures. CONCLUSIONS: In Canarian women, VDR genotype is not associated with changes in biochemical markers of bone remodelling or in bone mass or with the presence of osteoporosis or osteoporotic fractures.

Absorptiometry, Photon↗
PubMed1997

Identification and structural and functional characterization of human enamelysin (MMP-20).

A cDNA encoding a new human matrix metalloproteinase (MMP) has been cloned from RNA prepared from odontoblastic cells. The open reading frame of the cloned cDNA codes for a polypeptide of 483 amino acids and is extensively similar to the sequence of recently described porcine enamelysin, suggesting that the isolated cDNA codes for the human homologue of this enzyme. Human enamelysin (MMP-20) has a domain organization similar to other MMPs, including a signal peptide, a prodomain with the conserved motif PRCGVPD involved in maintaining enzyme latency, a catalytic domain with a Zn-binding site, and a COOH-terminal fragment similar to the sequence of hemopexin. The calculated molecular mass of human enamelysin is about 54 kDa, which is similar to that of collagenases or stromelysins. However, this human MMP lacks a series of structural features distinctive of these subfamilies of MMPs. The full-length human enamelysin cDNA has been expressed in Escherichia coli, and the purified and refolded recombinant protein is able to degrade synthetic peptides used as substrates of MMPs, confirming that human enamelysin belongs to this family of proteases. Furthermore, the recombinant human enamelysin is able to degrade amelogenin, the major protein component of the enamel matrix. On the basis of its degrading activity on amelogenin, and its highly restricted expression to dental tissues, we suggest that human enamelysin plays a central role in the process of tooth enamel formation. Finally, we have found that the human enamelysin gene (MMP-20) maps to chromosome 11q22, clustered to at least seven other members of the MMP gene family.

Amino Acid Sequence↗
PubMed1997

Prediction of left ventricular mass changes after renal transplantation by polymorphism of the angiotensin-converting-enzyme gene.

Cardiac complications are the main cause of death in renal transplant patients and left ventricular hypertrophy (LVH) may play a determinant role. An association between the insertion-deletion polymorphism of the angiotensin-converting enzyme (ACE) gene and LVH has been reported in adults. However, little is known about the genetic influence on left ventricular mass changes after renal transplantation, where unique environmental factors, such as cyclosporine A (CsA) and prednisone treatment concur. In fact, CsA treatment has recently been associated with the development of LVH. We prospectively determined the changes on cardiac structure and function, assessed by echocardiographic criteria, in 38 consecutive nondiabetic adults who received a cadaveric renal allograft. They were treated with cyclosporine and prednisone and maintained a good renal function during the follow-up. Echocardiographic studies (M-mode, 2-B and color flow Doppler) were performed without previous knowledge of the genetic typing, at the time of transplantation, and 6 and 12 months later. ACE alleles were typed using a PCR-based assay developed to ascertain the presence of an insertion (I)-deletion (D) polymorphism in intron 16 of the ACE gene. Patients with the so-called "unfavorable" DD genotype (N = 16) were compared with the ID or II genotypes (N = 22). The baseline left ventricular mass index was similar in patients with or without the unfavorable DD genotype (X +/- SE; 166.6 +/- 10.4 vs. 181.3 +/- 9 g/m2, respectively) and a similar proportion fulfilled the criteria of LVH (88% vs. 82%, respectively). The mean percent increase of the left ventricular mass index 12 months after renal transplantation was significantly higher in patients with the DD genotype compared to those with other genotypes (21.3 +/- 7.9 vs. -0.08 +/- 4.9%, respectively; P < 0.05). As a result, 94% of DD patients showed LVH at the end of the follow-up, while 68% of the ID or II patients had LVH (P < 0.05). In addition, the left ventricular ejection fraction significantly increased only in ID or II patients 12 months after transplantation with respect to baseline (ID/II patients, 70.4 +/- 1.5 vs. 63.7 +/- 1.8%; P < 0.05; DD patients, 68.3 +/- 2.1 vs. 63.3 +/- 2.9%). The deleterious effect of the DD genotype was independent of blood pressure, biochemical parameters, weight gain, and cumulative steroids dosages or cyclosporine levels. In conclusion, genetic factors determine the changes on cardiac structure and function after renal transplantation. The presence of the DD genotype of the ACE gene is a marker associated with an elevated risk of LVH in this population.

Adult↗
PubMed1997

Constitutive NOS isoforms account for gastric mucosal NO overproduction in uremic rats.

To study whether renal failure enhances gastric mucosal nitric oxide (NO) formation in the rat, we measured 1) in vivo NO concentration and 2) NO synthase (NOS) activity, content, and mRNA expression in gastric mucosal homogenates of uremic and sham-operated anesthetized rats. Gastric mucosal NO release was measured by an electrochemical technique. NOS content was analyzed by Western immunoblots, using specific monoclonal antibodies. Constitutive (Ca2+ dependent; cNOS) and inducible (Ca2+ independent; iNOS) NOS activities were assayed by following the conversion of L-[U-14C]arginine to [U-14C]citrulline. mRNA expression for the constitutive neuronal (ncNOS), endothelial (ecNOS), and iNOS isoforms was determined by reverse transcription-polymerase chain reaction. Under basal conditions, gastric mucosal NO concentration was significantly greater in uremic compared with control rats. This was accompanied by significantly greater gastric mucosal cNOS activity in uremic rats than in control rats, whereas no differences were observed in iNOS activity between both groups of animals. Moreover, total enzyme content and the levels of gastric mucosal mRNA expression for ncNOS, ecNOS, and iNOS showed no significant differences between uremic and sham-operated rats. These data confirm that, in uremic rats, enhanced Ca2+-dependent NOS activity is responsible for gastric mucosal NO overproduction and suggest that the main regulatory mechanism is not transcriptional but translational and/or posttranslational in nature.

Animals↗
PubMed1997

Expression of steroid sulfatase during embryogenesis.

Neurosteroids are steroids that are synthesized de novo in the brain from cholesterol and, in general, mediate their effects through ion-gated channel receptors such as gamma-aminobutyric acidA (GABA[A]) and N-methyl-D-aspartate receptors rather than through classical nuclear steroid hormone receptors. Steroid hormones are known to exist not only as free compounds, but also as sulfated derivatives. Pharmacological studies indicate that unconjugated and sulfated steroids, such as pregnenolone and pregnenolone sulfate, may have opposite effects on GABA(A) receptors. Thus, pregnenolone acts as a potent positive allosteric modulator of gamma-aminobutyric acid action at GABA(A )receptors, whereas pregnenolone sulfate acts as a potent negative modulator. Recent experiments also suggest that dehydroepiandrosterone and dehydroepiandrosterone sulfate may have distinct effects on growth of neurites from embryonic neocortical neurons in vitro. Thus, regulation of steroid sulfation may have profound behavioral and morphological effects on the nervous system. We, therefore, studied the developmental expression of the enzyme steroid sulfatase (STS), which converts sulfated steroids to free steroids. By in situ hybridization, STS messenger RNA was expressed in the embryonic mouse cortex, hindbrain, and thalamus during the last third of gestation. The sites of expression of STS were similar to those of P450c17, suggesting that these two enzymes may have concerted actions in similar functional processes.

Animals↗
PubMed1996

Characterization of the promoter region of human steroid sulfatase: a gene which escapes X inactivation.

The human X-linked steroid sulfatase gene (STS) was among the first genes shown to escape X inactivation. At least fourteen genes regulated in this fashion have now been recognized. They are dispersed into several regions of the X chromosome and may be controlled in a locus specific manner. Studies of the promoters of these genes could provide insights into the mechanism of X inactivation, however little information of this nature is currently available. For this reason we examined 5' flanking sequences of the human STS gene for promoter function. Four transcription start sites scattered over a 50bp region were identified. Functional domains of this TATA-less and GC poor promoter were identified by study of a series of terminal and internal deletions. A putative promoter sequence was identified which by itself exhibits little or no basal activity. However when combined with upstream regulatory elements, this segment showed weak but reproducible activity in a CAT (chloramphenicol acetyltransferase) reporter assay. Several regulatory domains acting as enhancers and repressors were subsequently identified. The relationship of this 5' sequence to the ability of the STS gene to escape X-inactivation is discussed.

Arylsulfatases↗
PubMed1996

Influence of vitamin D receptor genotype on bone mass changes after renal transplantation.

Renal transplant patients immunosuppressed with cyclosporine A (CsA) exhibit both a significant bone loss and an increased rate of bone fractures. An association between common allelic variants of the the vitamin D receptor (VDR) gene and bone mineral density and turnover has been reported in adults. However, the genetic influence on the rate of bone loss after renal transplantation has not been explored. We prospectively determined the changes in spinal mineral density in 34 consecutive nondiabetic adults who received a cadaveric renal allograft. Serum biochemical markers of bone metabolism and the vertebral mineral density (VMD) assessed by quantitative computed tomography were determined at the time of transplantation and three and twelve months later. In fifteen patients the histomorphometric features of iliac bone were analyzed at baseline and twelve months after transplantation. VDR alleles were typed by a PCR assay based on a polymorphic BsmI restriction site. Patients with the so-called "favorable" bb genotype (N = 12) were compared with those with the Bb or BB genotype (N = 22). Baseline VMD was similar in patients with or without the favorable bb genotype. Three months after transplantation the mean (+/- SD) VMD decreased 14 +/- 13.3 percent in all patients (16.5 +/- 13.1% in patients homozygous for the b allele and 13.77 +/- 13.9% in those with Bb or BB genotypes). The rate of VMD loss at this time inversely correlated with pretransplant PTH levels (r = -0.40; P < 0.05). Between 3 and 12 months after transplantation, patients with the favorable bb genotype recovered more VMD than those with Bb or BB types and showed a significantly higher Z score at the end of the follow-up (-0.37 +/- 1.16 vs. -1.10 +/- 1.20, respectively; P < 0.05). The beneficial effect of bb genotype was independent of the prevailing PTH levels and was also observed in those patients with a baseline PTH level < 250 pg/ml (final Z score: bb, -0.42 +/- 1.3, N = 11; Bb/BB, -1.35 +/- 0.8, N = 11, P < 0.05). At the end of follow-up, the histomorphometric studies showed a higher bone formation rate adjusted for PTH levels in patients with the Bb or BB genotype than in those with the favorable bb genotype (0.29 +/- 0.06 vs. 0.21 +/- 0.08 micron3/micron2/day respectively; P < 0.05). In conclusion, high pretransplant PTH levels enhance the early trabecular bone loss after renal transplantation, and functionally different alleles of the vitamin D receptor gene may condition the bone turnover and the degree of recovery of the bone mass.

Adult↗
PubMed1996

High phosphorus diet increases preproPTH mRNA independent of calcium and calcitriol in normal rats.

Phosphorus retention favors secondary hyperparathyroidism by decreasing calcitriol synthesis and serum calcium levels. However, a direct effect of high extracellular phosphorus on parathyroid (PTH) function, gene expression, and cell proliferation is still controversial. Normal rats were fed standard (St; 0.6% calcium, 0.6% phosphorus) or high phosphate (HP) diet (0.6% calcium, 1.2% phosphorus) for 18 days. To rule out transient decreases in serum calcium or calcitriol levels, sets of animals were sacrificed at different time periods after the last feeding (2, 4, 8, 12 or 24 hr). The HP diet led to hyperphosphatemia and secondary hyperparathyroidism and maximum differences in PTH levels were observed eight hours after feeding (St 29.4 +/- 15 vs. HP 87.9 +/- 56 pg/ml, mean +/- SD; P = 0.01). High levels induced by the HP diet prevented both hypocalcemia and low calcitriol levels at each study point. The HP diet also promoted a significant increase of PTH mRNA levels that peaked about eight hours after feeding (100% increase). This was confirmed at the cellular level by in situ hybridization. Parathyroid glands from animals fed the HP diet showed a 25% increase in volume with respect to the St diet (P = 0.01), and a typical pattern of hyperplasia was found. Parathyroid vitamin D receptor (VDR) mRNA levels were not modified by the HP diet. In conclusion, parathyroid gene expression per cell and parathyroid cell hyperplasia are stimulated by high dietary phosphorus independently of calcium and calcitriol. This effect is not mediated by alterations in the gene expression of the parathyroid calcitriol receptor. Our findings emphasize the importance of the control of hyperphosphatemia in chronic renal failure patients.

Animals↗
PubMed1996

Parathyroid gland calcium receptor gene expression is not regulated by increased dietary phosphorus in normal and renal failure rats.

The extracellular calcium regulation of parathyroid hormone (PTH) secretion is mediated by a cell surface G-protein-coupled calcium receptor (PCaR). The abnormal calcium sensing in renal failure could be the result of abnormalities of the PCaR. However, PCaR gene expression has been shown to be unaffected by 5/6 nephrectomy in the rat. Whether factors that enhance secondary hyperparathyroidism in renal failure affect the PCaR gene expression is not known. We studied normal rats (sham) (n = 40) and renal failure rats (3/4 nephrectomy) (n = 40). Half of the rats in each group received standard (0.6% calcium, 0.6% phosphorus) and half high phosphorus (0.6% calcium, 1.2% phosphorus) diet. Compared to the standard diet, the high phosphorus diet induced secondary hyperparathyroidism both in sham and in renal failure rats (intact PTH: 22.3 +/- 2.03 vs 54.3 +/- 7.6, P < 0.01, and 26.2 +/- 3.9 vs 178.7 +/- 23.2 pg/ml, P < 0.01, respectively). After the cloning of a rat PCaR cDNA fragment corresponding to the extracellular domain which showed an 89% homology with its bovine counterpart, a probe for Northern blot analysis was obtained. No differences in the PCaR mRNA/18s RNA ratio in high phosphorus compared to the standard diet group were observed, both in sham and in renal failure rats. In conclusion, PCaR gene expression is not involved in the genesis of the secondary hyperparathyroidism induced by a high phosphorus diet. An alternative means of increasing PTH secretion by phosphorus loading could be an alteration of the sensitivity of the PCaR to activation by extracellular calcium.

Amino Acid Sequence↗
PubMed1996

HLA-DR class II and ICAM-1 expression on tubular cells taken by fine-needle aspiration biopsy in renal allograft dysfunction.

BACKGROUND: Percutaneous biopsy is the method of choice for differential diagnosis of renal allograft dysfunction, although it is not risk-free. The use of less aggressive methods for diagnosis should limit the need for percutaneous biopsy to some specific situations. METHODS: We analysed 42 fine-needle aspiration biopsies from 36 kidney allograft recipients immunosuppressed with quadruple sequential therapy who suffered renal allograft dysfunction. Seven cases with stable renal function were used as controls and included as non-rejection cases in the analysis. In all aspirates the Corrected Increment was calculated and an immunocytochemical analysis of renal tubular cells with the monoclonal antibodies HLA-DR and ICAM-1 was performed. RESULTS: The Corrected Increment was increased in 13 out of 18 acute rejection cases and in one out of 31 non-rejection cases. HLA-DR expression was found in more than 30% of tubular cells from the aspirates in 16 out of 18 acute rejection cases and in eight out of 31 cases without rejection (P < 0.001). ICAM-1 expression was detected in more than 30% of tubular cells in 14 out of 18 cases with acute rejection, and in four out of 31 cases without acute rejection (P < 0.001). Interestingly, all acute vascular rejection cases (n = 6), and six out of 12 acute cellular rejection cases expressed both, HLA-DR and ICAM-1, in more than 30% of tubular cells. On the other hand, none of the non-rejection allograft dysfunctions or control samples showed more than 30% of tubular cells immunostained with both HLA-DR and ICAM-1 antibodies. CONCLUSIONS: The immunocytochemical analysis of HLA-DR and ICAM-1 on renal tubular cells taken by fine-needle aspiration biopsy, allows the diagnosis of acute cellular rejection and acute vascular rejection even when the Corrected Increment is not increased. Moreover, the risk of a core renal biopsy can be avoided when both tests are negative since an acute rejection is a remote possibility.

Acute Disease↗
PubMed1995

Amelogenin signal peptide mutation: correlation between mutations in the amelogenin gene (AMGX) and manifestations of X-linked amelogenesis imperfecta.

Formation of tooth enamel is a poorly understood biological process. In this study we describe a 9-bp deletion in exon 2 of the amelogenin gene (AMGX) causing X-linked hypoplastic amelogenesis imperfecta, a disease characterized by defective enamel. The mutation results in the loss of 3 amino acids and exchange of 1 in the signal peptide of the amelogenin protein. This deletion in the signal peptide probably interferes with translocation of the amelogenin protein during synthesis, resulting in the thin enamel observed in affected members of the family. We compare this mutation to a previously reported mutation in the amelogenin gene that causes a different disease phenotype. The study illustrates that molecular analysis can help explain the various manifestations of a tooth disorder and thereby provide insights into the mechanisms of tooth enamel formation.

Amelogenesis Imperfecta↗
PubMed1994

Isolation of a new gene GS2 (DXS1283E) from a CpG island between STS and KAL1 on Xp22.3.

A gene, GS2 (DXS1283E), was isolated from a CpG island located approximately midway between the steroid sulfatase (STS) and the Kallmann syndrome (KAL1) loci on the distal short arm of the human X chromosome. DNA sequencing of a GS2 cDNA clone revealed an open reading frame for a basic protein of 253 amino acid residues. A polymorphic CT dinucleotide repeat was found in the 3' untranslated region. The GS2 gene is expressed in all human tissues examined, including heart, brain, placenta, lung, liver, muscle, kidney, pancreas, and spleen. Several GS2 transcripts, ranging in size from 1.1 to 5.8 kb, were found among different tissues, suggesting tissue-specific processing of the GS2 transcript. Characterization of GS2 genomic clones revealed that the gene consists of 7 exons spanning over 26 kb, with a CpG island located in the first intron. The GS2 gene is transcribed toward Xpter, in the same direction as KAL1 but opposite to that of STS.

Amino Acid Sequence↗
PubMed1994

Isolation and characterization of XE169, a novel human gene that escapes X-inactivation.

Overlapping cDNA clones for a novel human X-linked gene, XE169, have been isolated and characterized. The composite cDNA sequence comprises 5910 bp (or 5901 bp) plus a poly(A) tail, with a 531 bp 5' and 696 bp 3' untranslated regions. The sequence represents a full-length or near full-length cDNA for the gene since Northern blot analysis reveals only a single prominent band approximately 6 kb in size. Alternative splicing generates two distinct transcripts either containing or missing a stretch of nine nucleotides in the XE169 single large open reading frame, which in turn predict two XE169 protein isoforms composed of 1557 and 1560 amino acids, respectively. Southern hybridization analysis of a panel of human-mouse somatic cell hybrids containing various portions of translocated human X chromosomes has assigned XE169 to the proximal half of the X short arm between Xp21.1 and the centromere. XE169 is expressed in multiple human tissues tested and homologous sequences exist on the human Y chromosome and in the genomes of five other eutherian mammals examined. RT-PCR analysis of somatic cell hybrids containing either an active or an inactive human X chromosome on a rodent background demonstrated that XE169 escapes X-inactivation.

Alternative Splicing↗
PubMed1990

Monoclonal analysis of fine-needle aspiration biopsy in kidney allografts.

To evaluate changes in T-lymphocyte subsets and DR expression on tubular cells, 74 fine-needle allograft aspirates (FNAB) were evaluated in 31 patients with cadaver kidney transplants. Monoclonal antibodies against T helper CD4+, cytotoxic/suppressor CD8+, and HLA-DR were used with an indirect alkaline-phosphatase-staining technique. Cases with acute rejection (n = 11) showed a significant increase of CD8+: CD4+ ratio versus those with stable function (n = 21), acute tubular necrosis (n = 10) or CsA toxicity (n = 7) (ANOVA F = 10; P less than 0.01). Cases with chronic rejection or CMV infection showed no differences in the CD8+: CD4+ ratio with the other groups. DR expression on tubular cells was frequently found in cases of acute rejection, chronic rejection and CMV (73%, 66%, and 43% respectively), occasionally found in CsA toxicity (14%), but never seen in controls or ATN. Both tests, the CD8+: CD4+ ratio and the DR expression on tubular cells, had a high sensitivity and specificity in differentiating acute rejection versus controls, acute tubular necrosis, and CsA toxicity. When both tests are taken together no case without rejection showed a CD8+:CD4+ ratio greater than 1.6 and DR expression on tubular cells. Cases with acute rejection who lost the graft (n = 6) had a CD8+:CD4+ ratio significantly greater than those who responded to antirejection therapy (n = 5) (t = 2.9; P less than 0.05).

Antibodies, Monoclonal↗