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Biomedical subjects

A Losada

Publications and source records attributed to A Losada.

At least 37 records · Page 2Linked to original sources
PubMed1999

Lung hypoplasia caused by nitrofen is mediated by down-regulation of thyroid transcription factor TTF-1.

Prenatal exposure to nitrofen induces lung hypoplasia and diaphragmatic hernias very similar to those in human disease, but the mechanisms are still unknown. Thyroid transcription factor 1 (TTF-1) is involved in lung ontogeny and regulation of the expression of surfactant proteins, and is likely abnormally expressed in nitrofen-induced lung hypoplasia. This study examines the effect of nitrofen on TTF-1 messenger RNA (mRNA) expression in the lungs of prenatal rat fetuses and a human lung-cell line (NCI-H441) that expresses both TTF-1 and surfactant proteins in vivo. Lungs from preterm fetuses harvested from rats with 100 mg nitrofen on gestational day 9.5 and NCI-H441 cells maintained in RPMI medium containing 10% fetal bovine serum and exposed to nitrofen for different times and concentrations were assayed for TTF-1 mRNA by northern blot analysis. mRNA for TTF-1 was decreased in nitrofen-exposed pups in comparison with controls, and exposure to nitrofen caused a dose- and time-related decrease in TTF-1 expression in H441 cell cultures. These results indicate that nitrofen downregulates TTF-1 both in vivo and in vitro. Since this interferes with lung development, it is reasonable to accept that lung hypoplasia in this model is in part due to the direct effect of the teratogen rather than to compression by the abdominal viscera herniated into the thorax. This mechanism should be explored in the clinical setting.

Animals↗
PubMed1999

HeT-A telomere-specific retrotransposons in the centric heterochromatin of Drosophila melanogaster chromosome 3.

We have isolated two yeast artificial chromosome (YAC) clones from Drosophila melanogaster that contain a small amount of dodeca satellite (a satellite DNA located in the centromeric region of chromosome 3) and sequences homologous to the telomeric retro-transposon HeT-A. Using these YACs as probes for fluorescence in situ hybridization to mitotic chromosomes, we have localized these HeT-A elements to the centric heterochromatin of chromosome 3, at region h55. The possible origin of these telomeric elements in a centromeric position is discussed.

Animals↗
PubMed1999

The analysis of Circe, an LTR retrotransposon of Drosophila melanogaster, suggests that an insertion of non-LTR retrotransposons into LTR elements can create chimeric retroelements.

Circe is a transposable element recently identified in Drosophila melanogaster which appears to be mostly associated with the constitutive heterochromatin. This element shows the structural features of a long terminal repeat (LTR)-containing retrotransposon: It is flanked by 240-bp-long terminal repeats, and its two open reading frames encode putative proteins resembling the gag and pol polyproteins of retroviruses. However, Circe displays striking similarities of both LOA and Ulysses, a non-LTR element and an LTR element, respectively. The result of its phylogenetic and structural analysis has allowed us to propose a new mechanism for non-LTR retrotransposon evolution.

Amino Acid Sequence↗
PubMed1999

Acrochordons are not a component of the Birt-Hogg-Dubé syndrome: does this syndrome exist? Case reports and review of the literature.

Multiple fibrofolliculomas, trichodiscomas, and acrochordons compose the triad of cutaneous lesions characterizing the Birt-Hogg-Dubé syndrome, inherited in an autosomal dominant fashion. We report a case of a family who had the triad of tumors of the Birt-Hogg-Dubé syndrome. Two members were observed clinically and histologically. Biopsies of the facial papules disclosed features of the fibrofolliculoma/trichodiscoma spectrum. Lesions that were clinically acrochordon-like proved to correspond to the same histopathologic spectrum. The characterization of the nature of the acrochordon-like lesions in our patients and the review of the literature allow us to question if acrochordons (skin tags) should be maintained as a component of this association. In light of our conclusion that fibrofolliculoma, trichodiscoma, and the acrochordon-like lesions are histologic variations of a single lesion, we further question whether the term "syndrome" is valid.

Female↗
PubMed1999

Necrobiosis lipoidica: a case with prominent cholesterol clefting and transepithelial elimination.

Transepithelial elimination of degenerated collagen through the hair follicle in necrobiosis lipoidica is rare, clinically manifesting as comedo-like plugs. Also unusual in necrobiosis lipoidica is the finding of cholesterol cleft formation. We report a case of necrobiosis lipoidica with transepithelial elimination of cholesterol crystals through hair follicles. This has been described in necrobiotic xanthogranuloma, demonstrating some overlap in the histopathologic findings in both necrobiotic granulomas. Additional criteria should be used to establish the diagnosis.

Aged↗
PubMed1999

Acquired cutaneous lymphangiectasia in a patient with cirrhotic ascites.

BACKGROUND: Lymphangiectasia results from acquired dilation of lymphatic vessels. Areas of skin affected by obstruction or destruction of lymphatic drainage are said to be prone to the development of lymphangiectasia. Cirrhosis is a cause of alterations of lymph flow. METHODS: Case report. RESULTS: We report a case of acquired, late-onset, lymphangiectasia associated with alcoholic hepatic cirrhosis. Lesions were scattered over the right, lower, anterior abdominal wall, a region that is drained by a common group of lymphatic vessels that were probably disordered. CONCLUSION: We think that this is the first reported case of lymphangiectasia associated with altered lymph flow in cirrhosis and ascites.

Adult↗
PubMed1998

Identification of Xenopus SMC protein complexes required for sister chromatid cohesion.

The structural maintenance of chromosomes (SMC) family is a growing family of chromosomal ATPases. The founding class of SMC protein complexes, condensins, plays a central role in mitotic chromosome condensation. We report here a new class of SMC protein complexes containing XSMC1 and XSMC3, Xenopus homologs of yeast Smc1p and Smc3p, respectively. The protein complexes (termed cohesins) exist as two major forms with sedimentation coefficients of 9S and 14S. 9S cohesin is a heterodimer of XSMC1 and XSMC3, whereas 14S cohesin contains three additional subunits. One of them has been identified as a Xenopus homolog of the Schizosaccharomyces pombe Rad21p implicated in DNA repair and the Saccharomyces cerevisiae Scc1p/Mcd1p implicated in sister chromatid cohesion. 14S cohesin binds to interphase chromatin independently of DNA replication and dissociates from it at the onset of mitosis. Immunodepletion of cohesins during interphase causes defects in sister chromatid cohesion in subsequent mitosis, whereas condensation is unaffected. These results suggest that proper assembly of mitotic chromosomes is regulated by two distinct classes of SMC protein complexes, cohesins and condensins.

Adenosine Triphosphatases↗
PubMed1998

Infantile pyramidal protrusion as a manifestation of lichen sclerosus et atrophicus.

BACKGROUND: A perineal infantile lesion previously described as "skin tag/fold" had recently been named infantile perianal pyramidal protrusion. It appears on the perineal median raphe of girls as a pyramidal soft tissue swelling, covered by smooth, red or rose-colored skin. Its pathogenesis is unknown. As in the case of other perianal lesions, knowledge about it is important, as concern about signs of child abuse grows. OBSERVATIONS: Four girls, 2 of them sisters, with infantile perianal pyramidal protrusion were studied. Three of these girls showed subtle clinical evidence of classic lichen sclerosus et atrophicus on first examination. The other girl developed vulvar lesions of lichen sclerosus et atrophicus months after the diagnosis of infantile perianal pyramidal protrusion. All 4 protrusions disclosed histopathological findings diagnostic of lichen sclerosus et atrophicus. CONCLUSIONS: Infantile perianal pyramidal protrusion is, at least in some patients, a peculiar form of lichen sclerosus et atrophicus that can precede other, more characteristic manifestations. We suggest changing the name to the more precise infantile perineal protrusion. Knowledge of this hitherto unrecognized clinical form of lichen sclerosus et atrophicus can help to explain anogenital symptoms and avoid its misinterpretation as a sign of sexual abuse.

Child↗
PubMed1997

Organization of DNA sequences near the centromere of the Drosophila melanogaster Y chromosome.

The structural analysis of a yeast artificial chromosome clone from Drosophila melanogaster enriched in dodecasatellite sequences has led us to find a new retrotransposon that we have called Circe. Moreover, this retrotransposon has allowed the isolation of a contig encompassing approximately 200 kb near the centromere of the Y chromosome, providing an entry point into a region from which very little sequence information has been obtained to date. The molecular characterization of the contig has shown the presence of HeT-A telomeric retrotransposons close to the centromere of the Y chromosome, suggesting a telocentric origin for this submetacentric chromosome.

Animals↗
PubMed1997

[Molecular genetic study in congenital myotonic dystrophy].

Congenital myotonic dystrophy (CMD) is the neonatal form of Steinert's myotonia. However, the symptoms and neuro-physiological findings are different from the classical adult form, there is a high mortality and early diagnosis of the condition is difficult. CMD occurs as a result of abnormal expansion of CTG triplets on chromosome 19. There is dominant autosomal transmission of this multi-systemic disorder, although when it occurs in children, it is the mother who is always the affected parent. Molecular genetic techniques enable unequivocal diagnosis of the condition, evaluation of anticipation and the possibility of offering genetic counselling to the families involved.

Chromosome Aberrations↗
PubMed1997

Adherence of Candida albicans strains isolated from AIDS patients. Comparison with pathogenic yeasts isolated from patients without HIV infection.

The adherence of yeasts to oral mucous cells is one of the main characteristics of the pathogenicity of this fungus. We studied adherence by means of a radiometric test to improve the method. We compared a sample of 40 strains of Candida albicans isolated from the buccal mucosa of HIV-infected patients with 40 strains isolated from non-HIV patients. We found that buccally isolated C. albicans strains from patients in the initial stages of AIDS adhered to oral mucous cells less than the buccally isolated C. albicans strains from subjects without HIV infection. Adherence among the strains of HIV patients increased with the disease stage until it exceeded that of the normal subjects in proportion to the decrease in the CD4/CD8 ratio. The selection of resistant strains by the preliminary antifungal treatments gave us a partial explanation for this increase. Further research should be carried out to compare these results with those obtained from atypical strains and species with high pathogenic potential, such as Candida dubliniensis, which is frequently isolated from advanced AIDS, in order to prevent systemic infections in these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Effects of the novel multiple-action agent carvedilol on severe nephrosclerosis in renal ablated rats.

Antihypertensive drugs have differing effects on renal hemodynamics and morphology. We analyzed whether the use of a new beta adrenoceptor antagonist and vasodilator, carvedilol (CVD), slows the progression of nephrosclerosis and whether the renoprotective effect as well as reduction in cardiac hypertrophy is dependent on the degree of blood pressure reduction. Fifty-four adult male Sprague-Dawley rats were distributed among five groups: group I served as untreated controls with 5/6 nephrectomy (Nx); group II, sham (no renal ablation or drug treatment); group III, CVD 5 (5/6 Nx and treatment with oral CVD at 5 mg/kg/day); group IV, CVD 10 (5/6 Nx and treatment with oral CVD at 10 mg/kg/day); and group V, CVD 20 (5/6 Nx and treatment with oral CVD at 20 mg/kg/day). Tail-cuff blood pressure and 24-hr urine samples were obtained before and at 3, 5 and 11 weeks of treatment with CVD. At the end of the study period, blood was taken to measure serum creatinine, plasma renin activity and CVD levels, as well as the remnant kidney and heart for morphological studies. There was a significant reduction in 24-hr U(ProtV) in all the CVD-treated groups, and it was increasingly evident with the highest dose used. However, only rats receiving doses of 10 and 20 mg/kg/day of CVD exhibited significant decreases in blood pressure. Elevated serum creatinine levels seen in untreated controls were significantly decreased by CVD in treated rats (P < .01), indicating that glomerular filtration rate was improved by this drug. This was associated with a significant increase in U(NaV). Concomitant and significant (P < .01) decreases in plasma renin activity were observed in sham and CVD-treated rats. CVD-treated animals had considerably reduced renal damage (P < .01) and cardiac hypertrophy (P < .01) compared with untreated controls. These data indicate that CVD is effective in delaying progression of renal damage and provides beneficial effects in the remnant kidney and cardiac hypertrophy, even at nonhypotensive doses.

Adrenergic beta-Antagonists↗
PubMed1996

Organochlorine pesticide residues in bovine milk from Leon (Spain).

Residue levels of the organochlorine pesticides (alpha-HCH, lindane, heptachlor-epoxide, aldrin, endrin, dieldrin, o,p'-TDE, p,p'-TDE, p,p'-DDE and p,p'-DDT) were determined in raw bovine milk and compared with the maximum levels allowed by the European Union (EU) in these foods. The highest incidence percentage of the ten insecticides measured was for lindane, followed by alpha-HCH and aldrin. Moreover, the highest mean residue level was for alpha-HCH. None of the samples analyzed exceeded the maximum levels allowed by the EU.

Animals↗