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Biomedical subjects

J Marcos

Publications and source records attributed to J Marcos.

At least 19 recordsLinked to original sources
PubMed2004

Paralogues of porcine aromatase cytochrome P450: a novel hydroxylase activity is associated with the survival of a duplicated gene.

The gonadal and placental paralogues of porcine aromatase cytochrome P450 (P450arom) were examined for novel catalytic properties to shed light on the evolutionary survival of duplicated copies of an enzyme critical to reproduction. Recombinant gonadal P450arom catalyzed the formation of a novel metabolite from testosterone, identified by gas chromatography/mass spectrometry and biochemical analyses as 1 beta-hydroxytestosterone (1 beta OH-T), in almost equal proportion to 17beta-estradiol (E(2)). This activity was absent in reactions with the porcine placental paralogue (or other orthologues) of P450arom and was minimal with androstenedione. Incubations with both porcine enzymes and with bovine and human P450arom demonstrated that 1 beta OH-T was not aromatizable, and 1 beta OH-T activated the androgen receptor of prostate cancer cells in vitro. Porcine testicular and follicular granulosa tissues synthesized 1 beta OH-T, which was also detected in testicular venous plasma. These results constitute the first of identification of a novel, perhaps potent, nonaromatizable metabolite of testosterone, whose synthesis (paradoxically) can be definitively ascribed to the activity of the gonadal paralogue of porcine P450arom. It probably represents an evolutionary gain of function associated with fixation and the survival of the genes after CYP19 duplication. Novel activities and adaptive functions may exist among other duplicated vertebrate aromatases.

Animals↗
PubMed2004

Analysis of molecular heterogeneity of prolactin in human systemic lupus erythematosus.

Hyperprolactinemia without clinical manifestations has been reported in some patients with systemic lupus erythematosus (SLE) because an increase of prolactin (PRL) is produced due to the BIG/BIG molecular variant (molecular variant < 150 kD). This research project aimed to determine levels of PRL: its bioactive form, the little nonglycosylated form (NGPRL) and variants with decreased bioactivity such as the BIG/BIG and the little glycosylated (GPRL), in 29 women and five men with SLE. PRL was assayed by IRMA with a kit from Immunotech Laboratory, the BIG/BIG form by precipitation with polyethyleneglycol 6000, and the NGPRL and GPRL by chromatography on Concanavalin-A- Sepharose. Increased PRL was detected in seven patients (20.6%) of whom three had increased BIG/BIG, six had increased GPRL and only four had increased NGPRL. The three cases with increased BIG/BIG were contrasted by chromatography on Sephadex G-100. No increased PRL or any of the other variants assayed were found in men. Results were similar when PRL was evaluated in the same blood samples by a different IRMA (DPC Laboratory). The etiology of the hyperprolactinemia in some of these patients is unknown, but their lack of symptoms (galactorrhea or amenorrhea) could be due to the BIG/BIG forms and basically to the glycosylation of the hormone. As for the relation between PRL and SLE activity, we found that hyperprolactinemic patients were younger, had a shorter history of illness, although it was not statistically significant, and a higher SLEDAI score. This would indicate a relation between hyperprolactinemia and lupus activity. The patients with increased BIG/BIG form also had a very active illness at the time of the study.

Adult↗
PubMed2002

Fast screening of anabolic steroids and other banned doping substances in human urine by gas chromatography/tandem mass spectrometry.

A fast and sensitive method for the comprehensive screening of anabolic agents and other banned doping substances using gas chromatography/tandem mass spectrometry (GC/MS/MS) with an external ionization ion trap mass spectrometer is presented. The method takes advantage of the resolving power of MS/MS to eliminate background interferences, thus speeding up the chromatographic analysis. For each compound, different fragmentation reactions were studied and their collision energies optimized to obtain the best sensitivity in terms of their signal-to-noise ratio (S/N). A dramatic reduction in overall analysis time was achieved compared with other common approaches. More than 50 substances could finally be monitored in less than 7.4 min with detection limits (S/N >3) lower than 0.5 ng ml(-1) for most of the compounds with special sensitivity requirements according to the International Olympic Committee (IOC). A validation procedure for qualitative analysis was performed. The selectivity of the method showed that no interfering peaks were observed at the retention time of the analytes. Good intermediate precision, below 25% for most of the compounds, and robustness were observed. The optimized method was successfully applied to analyse more than 100 real human urine samples with optimum sensitivity and specificity rates.

Anabolic Agents↗
PubMed2000

Syntactic comprehension, verbal memory, and calculation abilities in Spanish-English bilinguals.

This article analyzes the interfering effect of the second language (L2) on the first language (L1) in native Spanish speakers living in the United States. We examined 3 linguistic aspects: (a) syntactic comprehension, (b) verbal memory, and (c) calculation abilities. We carried out 2 different studies. In the 1st study, we studied syntactic understanding in 50 Spanish-English bilinguals. For all participants, L1 was Spanish and L2 was English, and all learned English early in life and had attended English schools. Results for the Spanish Syntactic Comprehension Test (Marcos & Ostrosky, 1995) were compared with the normative results obtained with 40 Spanish monolingual participants. We observed that the closer to the English syntax the sentences were, the easier it was for the participants to understand them. Participants who had been exposed to English between the ages of 5 and 12 outperformed participants exposed to English before 5 years of age. Language preference correlated with syntactic comprehension. Women outperformed men. In the 2nd study, verbal memory and calculation abilities were examined in L1 and L2 in a group of 85 Spanish-English bilinguals. Parallel versions of the different tests were administered in Spanish and English. The results indicated some significant differences between the 2 languages in several verbal learning and calculation ability subtests. Most of the verbal memory subtests were better performed in L1. Scores on tasks measuring speed and calculation accuracy were higher in the participant's native language. Best spoken language proved to be a significant variable in some verbal memory subtests performed in English but not in Spanish. We analyze implications of bilingualism in neuropsychological testing. We also present some suggestions to minimize the bilingualism effect.

Adult↗
PubMed1998

[Iron deficiency and pica].

PURPOSE: To study the relationship between pica and iron-lack anaemia in a series of iron-deficiency patients in order to establish the pathogenesis of such relationship. PATIENTS AND METHODS: Four-hundred and thirty-three patients were analysed. Pica was studied by introducing certain diet queries into the clinical history. All patients received oral iron and were periodically controlled with the usual clinico-haematological procedures. RESULTS: Pica was present in 23 patients (5.3%). Eight nourishing (namely, coffee grains, almonds, chocolate, ice, lettuce, carrots, sunflower seeds and bread) and 2 non-nourishing (clay and paper) substances were involved. A second episode of pica appeared in 9 cases upon relapsing of iron deficiency. Both anaemia and pica were cured by etiologic and substitutive therapy in all instances. No clear correlation was found with either socio-economic status or pathogenetic causes of iron deficiency and pica, and no haematological differences were seen between patients with pica and those without this alteration. CONCLUSIONS: (1) The pathogenesis of pica is unclear, although it appears unrelated to the degree of iron deficiency. (2) According to the findings in this series, pica seems a consequence of iron deficiency rather than its cause. (3) Adequate therapy can cure both conditions, although pica may reappear upon relapse of iron deficiency.

Adolescent↗
PubMed1996

Postural myoclonus induced by phenytoin.

Involuntary movements are an infrequent complication of treatment with phenytoin and include tremor, asterixis, myoclonus, parkinsonism, and dyskinesias. The mechanism by which phenytoin exerts its actions is unclear. Phenytoin has been observed to exert variable effects on dopamine metabolites and also may induce changes in serotonergic activity. In this report, we discuss the available experimental evidence concerning the possible mechanisms of involuntary movements induced by phenytoin. We describe a case of postural myoclonus during treatment with phenytoin.

Aged↗
PubMed1996

A three-dimensional virtual model of the head generated from digitalized CT or MR images for anatomical-radiological and neurosurgical evaluations.

A computer-generated virtual model has been developed that reconstructs the head in three dimensions from digitalized images obtained with magnetic resonance and computerized tomography. Through programming and the use of commercial graphic animation software, we have developed the whole process of the rotation of the head on different spatial planes. The procedure permits multidirectional anatomical sections to be made on the structure of the head, providing a true dynamic and user-friendly anatomical-radiological atlas. The system serves as a virtual model for the localization of an ideal surgical approach to any lesion thus avoiding possible neurological lesions.

Anatomy, Artistic↗
PubMed1980

Male pseudohermaphroditism with 17 alpha-hydroxylase deficiency. A case report.

A case of male pseudohermaphroditism with 17 alpha-hydroxylase deficiency is reported in a 23-year-old woman presenting with primary amenorrhoea and a history of bilateral inguinal hernia repair. She was tall, had hypoplastic external genitalia with a blood pressure of 220/140 mm Hg. Her karyotype was XY. Acute adrenal failure occurred following exploratory laparotomy. After treatment with glucocorticoids and oestrogens, the hormone and electrolyte profiles returned to normal and the blood pressure fell. The biochemical implications of this enzyme deficiency are discussed.

Adrenal Hyperplasia, Congenital↗
PubMed1979

Radiologic aspects of hepatic echinococcosis. Value of the intravenous viscerogram and computed tomography.

Over five years, 105 patients with hepatic echinococcosis were studied. Plain radiographs of the hepatic area yielded the correct diagnosis in 35% of patients. Intravenous viscerograms were diagnostic in all but 14 of the patients (an accuracy of 83%). Computed tomography was performed in 19 cases and proved the most efficient of the techniques--it was diagnostic in all 19 cases. The radiological signs of this entity are discussed.

Calcinosis↗
PubMed1978

Radiological characteristics of primary intestinal lymphoma of the "Mediterranean" type: observations on twelve cases.

Radiological findings in 12 cases of "Mediterranean" lymphoma are analyzed, 4 of which are associated with gammapathy. These findings have not permitted differentiation of this type of lymphoma from those classically described, although there are two signs that strongly suggest this diagnosis: extension of the lesions along wide areas of the small intestine, almost always including the duodenum, and spiculation of the mucosal fold edges, representing massive plasmocyte infiltration of the lamina propria. The principal clinical, immunological, and pathological aspects are described, as well as the radiological differential diagnosis.

Adult↗
PubMed1975

Radiological characteristics of perforated pulmonary hydatid cysts.

Perforation of pulmonary hydatid cysts into the bronchial tree was seen in 56 of 239 cases. The resulting radiological signs are much more specific than those seen prior to perforation. These signs are described and correlated with the cystic structures that give rise to them. Perforation into the pleural cavity, seen in 5 cases, may result in secondary hydatidosis, as happened in one case.

Echinococcosis↗